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Published  by 

The  Palaeontological  Association  • London 
Price  £32-50 


THE  PALAEONTOLOGICAL  ASSOCIATION 

The  Association  was  founded  in  1957  to  promote  research  in  palaeontology  and  its  allied  sciences. 


COUNCIL  1990-1991 

President : Professor  J.  W.  Murray,  Department  of  Geology,  The  University,  Southampton  S09  5NH 
Vice-Presidents'.  Dr  M.  Romano,  Department  of  Geology,  University  of  Sheffield,  Sheffield  S3  7HF 
Dr  P.  R.  Crowther,  City  of  Bristol  Museum  and  Art  Gallery,  Queen’s  Road,  Bristol  BS8  1RL 
Treasurer  : Dr  M.  E.  Collinson,  Department  of  Biology,  King’s  College,  London  W8  7AH 
Membership  Treasurer  : Dr  H.  A.  Armstrong,  Department  of  Geological  Sciences,  The  University,  South  Road, 

Durham  DH1  3LE 

Institutional  Membership  Treasurer  : Dr  A.  W.  Owen,  Department  of  Geology  and  Applied  Geology, 

University  of  Glasgow,  Glasgow  G12  8QQ 

Acting  Secretary  : Dr  J.  A.  Crame,  British  Antarctic  Survey,  High  Cross,  Madingley  Road,  Cambridge  CB3  OET 
Circular  Reporter  : Dr  D.  Palmer,  Department  of  Geology,  Trinity  College,  Dublin  2 
Marketing  Manager  : Dr  C.  R.  Hill,  Department  of  Palaeontology,  British  Museum  (Natural  History),  London  SW7  5BD 
Public  Relations  Officer:  Dr  M.  J.  Benton,  Department  of  Geology,  University  of  Bristol,  Bristol  BS8  1RJ 

Editors 

Dr  M.  J.  Benton,  Department  of  Geology,  University  of  Bristol,  Bristol  BS8  1RJ 
Dr  J E.  Dalingwater,  Department  of  Environmental  Biology,  University  of  Manchester,  Manchester  M13  9PL 
Dr  D.  Edwards,  Department  of  Geology,  University  of  Wales  College  of  Cardiff,  Cardiff  CF1  3YE 
Dr  P.  D.  Lane,  Department  of  Geology,  University  of  Keele,  Keele,  Staffordshire  ST5  5BG  (co-opted) 

Dr  P.  A.  Selden,  Department  of  Extra-Mural  Studies,  University  of  Manchester,  Manchester  Ml 3 9PL 
Dr  P.  D.  Taylor,  Department  of  Palaeontology,  British  Museum  (Natural  History),  London  SW7  5BD 

Other  Members 

Dr  E.  A.  Jarzembowski,  Brighton  Dr  W.  J.  Kennedy,  Oxford  Dr  D.  M.  Martill,  Milton  Keynes 
Dr  A.  R.  Milner.  London  Dr  R.  A.  Spicer,  Oxford 

Overseas  Representatives 

Argentina : Dr  M.  O.  Mancenido,  Division  Paleozoologia  invertebrados,  Facultad  de  Ciencias  Naturales  y Museo,  Paseo  del 
Bosque,  1900  La  Plata.  Australia : Dr  K.  J.  McNamara,  Western  Australian  Museum,  Francis  Street,  Perth,  Western 
Australia  6000.  Canada:  Professor  S.  H.  Williams,  Department  of  Earth  Sciences,  Memorial  University,  St  John’s, 
Newfoundland  A1B  3X5.  China:  Dr  Chang  Mee-mann,  Institute  of  Vertebrate  Palaeontology  and  Paleoanthropology, 
Academia  Sinica,  P.O.  Box  643,  Beijing.  Dr  Rong  Jia-yu,  Nanjing  Institute  of  Geology  and  Palaeontology,  Chi-Ming-Ssu, 
Nanjing.  France:  Dr  J.-L.  Henry,  Institut  de  Geologie,  Universite  de  Rennes,  Campus  de  Beaulieu,  Avenue  du  General 
Leclerc,  35042  Rennes  Cedex.  Iberia:  Prof.  F.  Alvarez,  Departamento  de  Geologia,  Universidad  de  Oviedo,  C/.  Jesus  Arias 
de  Velasco,  s/n.  33005  Oviedo,  Spain.  Japan : Dr  I.  Hayami,  University  Museum,  University  of  Tokyo,  Hongo  7-3-1,  Tokyo. 
New  Zealand:  Dr  R.  A.  Cooper,  New  Zealand  Geological  Survey,  P.O.  Box  30368,  Lower  Hutt.  Scandinavia:  Dr  R. 
Bromley,  Fredskovvej  4,  2840  Holte,  Denmark.  U.S.A. : Prof.  A.  J.  Rowell,  Department  of  Geology,  University  of  Kansas, 
Lawrence,  Kansas  66044.  Prof.  N.  M.  Savage,  Department  of  Geology,  University  of  Oregon,  Eugene,  Oregon  97403.  Prof. 
M.  A.  Wilson,  Department  of  Geology,  College  of  Wooster,  Wooster,  Ohio  44961.  Germany:  Prof.  F.  T.  Fursich, 
Institut  fur  Palaontologie,  Universitat,  D8700  Wurzburg,  Pliecherwall  1 

MEMBERSHIP 

Membership  is  open  to  individuals  and  institutions  on  payment  of  the  appropriate  annual  subscription.  Rates  for  1991  are: 
Institutional  membership  . . £60-00  (U.S.  $108)  Student  membership  . . . . £11-50  (U.S.  $20) 

Ordinary  membership  . £28  00  (U.S.  $50)  Retired  membership  ....  £14-00  (U.S.  $25) 

There  is  no  admission  fee.  Correspondence  concerned  with  Institutional  Membership  should  be  addressed  to  Dr  A.  W.  Owen, 
Department  of  Geology  and  Applied  Geology,  The  University,  Glasgow  GI2  8QQ.  Student  members  are  persons  receiving  full- 
time instruction  at  educational  institutions  recognized  by  the  Council.  On  first  applying  for  membership,  an  application  form 
should  be  obtained  from  the  Membership  Treasurer:  Dr  H.  A.  Armstrong,  Department  of  Geological  Sciences,  The 
University,  South  Road,  Durham  DH1  3LE.  Subscriptions  cover  one  calendar  year  and  are  due  each  January;  they  should 
be  sent  to  the  Membership  Treasurer.  All  members  who  join  for  1991  will  receive  Palaeontology , Volume  34,  Parts  1-4. 
Enquiries  concerning  back  numbers  should  be  directed  to  the  Marketing  Manager. 

Non-members  may  subscribe,  and  also  obtain  back  issues  up  to  3 years  old,  at  cover  price  through  Basil  Blackwell  Ltd, 
Journal  Subscription  Department,  Marston  Book  Services,  P.O.  Box  87,  Oxford  OX2  0DT,  England.  For  older  issues 
contact  the  Marketing  Manager. 


Cover:  Bolboforma  intermedia  Daniels  and  Spiegler  (Incertae  Sedis,  possibly  a calcified  algal  cyst)  from  Site  552A,  southwest 
margin  of  Rockall  Plateau,  late  Miocene  NN9-10.  x 800.  Bolboforma  was  planktonic  and  cysts  are  found  in  epicontinental 
shelf  sea  deposits,  thus  providing  a useful  biostratigraphic  link  with  oceanic  sequences. 


LATE  TREMADOC  GRAPTOLITES  FROM  WESTERN 

NEWFOUNDLAND 


by  S.  HENRY  WILLIAMS  and  ROBERT  K.  STEVENS 


Abstract.  The  Cow  Head  Group  of  western  Newfoundland  preserves  a sequence  of  carbonate-rich  sediments 
ranging  from  middle  Cambrian  to  middle  Ordovician.  It  yields  a rich  graptolite  fauna  both  with  flattened 
specimens  in  black  shales  and  cherts,  and  three-dimensional  and  flattened  material  in  nodular  limestones  which 
may  be  isolated  from  the  rock  by  acid  extraction.  A continuous  succession  is  present  across  the 
Tremadoc-Arenig  boundary,  containing  a well  represented  graptolite  assemblage  which  is  here  referred  to  the 
A.  victoriae  Zone.  Late  Tremadoc  graptolite  faunas  have  been  documented  from  many  localities  around  the 
world,  but  are  commonly  found  in  stratigraphically  incomplete  sequences  and  have  only  been  known 
previously  from  non-isolated  material.  The  Cow  Head  Group  faunas  comprise  both  flattened  and  isolated 
material,  allowing  detailed  observation  of  proximal  developments  to  be  compared  with  overall  rhabdosome 
forms.  Several  taxa  possess  overall  forms,  proximal  structures  and  thecal  styles  somewhat  similar  to 
dichograptids  and  sigmagraptines  found  in  the  early  Arenig,  but  they  all  possess  a sicular  bitheca;  some  have 
additional  bithecae  associated  with  the  autothecae,  and  dichotomous  branching  is  commonly  far  more 
variable.  Because  of  these  differences,  all  taxa  described  from  this  interval  are  considered  to  belong  to  the 
Anisograptidae,  necessitating  some  generic  reassignment  and  the  erection  of  several  new  taxa.  These  include 
Kiaerograptus  undulatus  sp.  nov.  K.  magnus  sp.  nov.,  Paratemnograptus  isolatus  sp.  nov.,  Aorograptus  gen. 
nov.,  Adelograptus  altus  sp.  nov.  and  A.  filiformis  sp.  nov. 

During  the  latter  part  of  the  Tremadoc  Series,  some  of  the  planktonic  graptolites  (traditionally 
assigned  to  the  Dendroidea)  which  were  components  of  Bulman's  (1954)  Anisograptid  Fauna, 
underwent  significant  evolutionary  changes.  These  involved  the  loss  of  bithecae  and  sclerotized 
stolons  and  general  simplification  of  stipe  geometry.  This  Anisograptid  Fauna  gave  way  to  the 
typical  graptoloid-dominated  Dichograptid  Fauna  by  the  earliest  Arenig.  The  adaptive  reasons  for 
the  changes  are  not  fully  understood;  the  loss  of  bithecae  which  are  generally  considered  to  have 
played  a role  in  reproduction  (e.g.  Kozlowski  1949;  Rickards  1977)  is  particularly  puzzling.  Fortey 
and  Cooper  (1986)  have  challenged  the  traditional  high-level  classification  of  the  graptolites;  they 
assign  all  nematophorous  (planktonic  or  epiplanktonic)  graptolites  to  the  Graptoloidea,  including 
the  anisograptids  such  as  Rhabdinopora  (ex  Dictyonema  see  Erdtmann  1982).  In  their  scheme,  only 
forms  which  remained  benthic  throughout  astogeny  are  referred  to  the  Dendroidea. 

Cooper  (1979/))  reviewed  the  global  distribution,  zonation  and  correlation  of  Tremadoc 
graptolite  assemblages.  Late  Tremadoc  assemblages,  which  Cooper  assigned  to  an  Assemblage  4. 
are  characterized  by  a large  and  diverse  graptolite  fauna  including  species  formerly  assigned  to 
Adelograptus , Bryograptus , Kiaerograptus , Temnograptus , Tetragraptus , Didymograptus  and 
Clonograptus.  His  following  Assemblage  5 marks  the  base  of  the  Arenig  and  is  characterized  by  the 
appearance  of  Tetragraptus  approximates.  Assemblage  4 faunas  are  perhaps  best  known  from 
Australasia;  other  areas  where  they  occur  include  China  (southwest,  Kiangsi),  USSR  (Kazakhstan, 
Taimyr),  Europe  (Oslo  Region,  Sweden  and  south-west  Spain),  and  North  America  (Yukon,  Texas, 
Quebec  and  western  Newfoundland).  Although  many  graptoli tic  units  are  therefore  present  through 
this  interval,  graptolites  of  late  Tremadoc  age  are  not  commonly  found  well  preserved,  neither  are 
they  normally  in  sequence  with  stratigraphically  older  and  younger,  graptolite-bearing  strata.  In 
addition,  evidence  for  a late  Tremadoc  age  from  other  taxa  is  usually  lacking,  and  little  or  no  late 
Tremadoc  isolated,  three-dimensional  material  has  been  described  to  date. 

Martin  Point  (Text-fig.  1)  was  the  only  locality  in  western  Newfoundland  discussed  by  Cooper 


IPalaeontology,  Vol.  34,  Part  1,  1991,  pp.  1-47,  7 pls.| 


© The  Palaeontological  Association 


2 


PALAEONTOLOGY,  VOLUME  34 


, ZA  | | Lower  Head  Fm. 


Parautochthonous 
cover  sequence 


Rocky  Harbour 
Melange 


Long  Range  Complex 

Section  studied 
0 5 


text-fig.  I.  Geological  map  of  the  Cow 
Head  region,  western  Newfoundland  (after 
Williams  and  Stevens  1988,  text-fig.  2). 


(19796).  His  data  were  derived  from  Erdtmann  (1971u,  b)  who  in  turn  had  relied  on  preliminary 
information  from  Kindle  and  Whittington  (1958).  Since  that  time,  other  sections  yielding  late 
Tremadoc  graptolites  have  been  described  by  James  and  Stevens  (1986),  and  it  is  both  on  Martin 
Point  and  these  additional  sections  that  the  present  paper  is  based.  The  importance  of  early 
Ordovician  graptolites  from  the  Cow  Head  Group  has  recently  been  illustrated  through  the  work 
of  Williams  and  Stevens  (1988u),  who  described  the  Arenig  faunas.  Rich  assemblages  of  flattened 
material  are  found  in  structurally-simple  stratigraphic  sequences,  and  are  occasionally  associated 
with  three-dimensional,  isolatable  material  from  nodular  limestones  at  the  same  horizons.  Not  only 
is  there  a stratigraphically-continuous  sequence  of  graptolites  from  the  late  Tremadoc  through  to 
the  earliest  Arenig  T.  approximate  Zone,  but  the  graptolites  are  also  associated  with  other  fossil 
groups  within  the  black  shales  and  nodular  limestones,  including  conodonts  and  trilobites. 


GEOLOGICAL  AND  STRUCTURAL  SETTING  OL  THE  COW  HEAD  GROUP 

During  the  late  Cambrian  and  early  Ordovician,  western  Newfoundland  formed  part  of  the  low 
latitude  Laurentian  continental  margin,  facing  the  Iapetus  Ocean  to  the  south-west  (Williams  and 
Stevens  1974).  This  area  now  lies  within  the  Humber  tectonostratigraphic  zone  of  the  Appalachians 
(Williams  1978).  Two  distinct  sedimentary  sequences  were  deposited  along  the  margin;  on  the  shelf 
itself,  a predominately  carbonate  sequence  (James  et  al.  1989)  formed  in  shallow,  tropic  seas,  while 
on  the  continental  slope  and  rise  a coeval  sequence  of  shales  and  turbidites,  the  Humber  Arm 
Supergroup,  was  deposited.  The  shelf/continental  rise  has  since  been  destroyed  by  subsequent 
tectonism,  and  its  former  location  can  only  be  surmised  (Rodgers  1968).  That  part  of  the  Humber 
Arm  Supergroup  on  the  Northern  Peninsula  characterized  by  limestone  conglomerates,  thin  bedded 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


3 


limestones,  and  shales  is  referred  to  as  the  Cow  Head  Group  (Kindle  and  Whittington  1958;  James 
and  Stevens  1986). 

The  Humber  Arm  Supergroup,  including  the  Cow  Head  Group,  was  transported  westward 
during  Llanvirn  tectonism.  It  was  pushed  over  the  shelf  sequence  as  part  of  a large  allochthon,  the 
Humber  Arm  Allochthon.  Since  the  upper  part  of  the  allochthon  contains  large  slabs  of  ophiolite- 
derived  material  and  fragments  of  volcanic  islands,  the  tectonism  was  probably  the  result  of  the 
abortive  subduction  of  the  Laurentian  margin  under  Iapetus.  Remarkably,  the  slices  of  allochthon 
containing  the  Cow  Head  Group  escaped  with  little  deformation  during  transport,  although  later 
(early  Devonian?)  imbrication  resulted  in  some  brittle-style  deformation.  The  lack  of  pervasive 
alteration  is  demonstrated  well  by  the  conodont  Colour  Alteration  Index  (CAI),  which  reaches  only 
1-5  in  the  Cow  Head  region  (Nowlan  and  Barnes  1987).  As  a result  of  these  tectonic  events  and 
subsequent  erosion,  the  Cow  Head  Group  is  now  exposed  in  a series  of  thrust  slices  that  span  some 
25  km  across  depositional  strike  (Text-fig.  2). 


Key  to  lithological  sections 


60000000^ 

00000OO0V 

000O0000<  Carbonate  conglomerate  or 
0OOOOOOo{  breccia,  clasts  > 25  cm 

Conglomerate  with  finer, 
tabular  and  subequant  clasts 


Parted  limestone 

Irregularly  bedded  limestone 

Ribbon  limestone 

Nodular  limestone 

Quartzose  dolostone 

Shale:  black  (bk),  brown  (bn) 
green  (gn),  grey  (gy).  red  (rd) 

▼ Chert 

/ Graptolitic  interval 


text-fig.  2.  Lithological  logs  through 
Cow  Head  and  St  Paul’s  Inlet. 


ST  PAUL'S  INLET 

the  Cow  Head  Group  for  the  Tremadoc-Arenig  boundary  interval  at 
indicating  graptolitic  horizons  (after  James  and  Stevens,  1986). 


Geology  of  the  Cow  Head  Group 

The  following  account  is  based  largely  on  James  and  Stevens  (1986),  from  whom  additional  details 
may  be  obtained.  The  Cow  Head  Group  consists  of  up  to  500  m of  shales,  hemipelagic  limestones. 


4 


PALAEONTOLOGY,  VOLUME  34 


carbonate  grainstones  and  limestone  conglomerates.  The  detrital  carbonates  were  deposited 
through  the  action  of  lime  turbidites  and  limestone  debris  flows  derived  in  part  from  lithified  or 
semi-lithified  sediments  of  the  shelf  edge  and  upper  slope  to  the  north-west.  Most,  but  not  all,  clasts 
from  any  particular  conglomerate  yield  fossils  from  a limited  stratigraphic  range  and  are 
approximately  coeval  with  fossils  from  the  overlying  shales  and  limestones.  This  permits  an 
unusually  high  degree  of  correlation  between  typical  shelf  faunas  and  those  inhabiting  deeper,  open 
ocean  environments,  although  care  needs  to  be  exercised  in  recognizing  reworked  faunal 
assemblages.  The  most  common  fossils  in  the  limestone  clasts  are  trilobites  (see  Kindle  and 
Whittington,  1958),  brachiopods  (see  Ross  and  James  1987)  and  conodonts  (see  Pohler  et  at.  1987) 
of  the  North  American  conodont  province.  The  interbedded  shales  and  limestones  yield  graptolites, 
conodonts  of  the  North  Atlantic  province,  inarticulate  brachiopods  and  occasional  trilobites, 
together  with  rare  examples  of  other  invertebrates  and  possible  fish  remains.  The  graptolite  record 
extends  from  the  middle  Cambrian  to  the  early  middle  Ordovician  (late  Arenig);  details  of  the  post- 
Tremadoc,  early  Ordovician  graptolites  are  given  by  Williams  and  Stevens  (1987,  1988a).  A fuller 
account  of  previous  investigations  into  graptolites  from  the  Cow  Head  Group  is  also  provided  in 
the  latter  work.  Other  recent  publications  on  the  invertebrate  faunas  include  accounts  of  the 
conodonts  straddling  the  Cambrian-Ordovician  boundary  (Barnes  1988)  and  the  Tremadoc-Arenig 
boundary  (Stouge  and  Bagnoli  1988),  and  notes  on  the  Radiolaria  (lams  and  Stevens,  1988;  Stevens 
and  lams  1988).  A monographic  study  of  the  Cambrian  trilobite  fauna  has  recently  been  completed 
by  Ludvigsen  et  ah  (1989). 

Biostratigraphic  correlation  between  the  isolated  sections  through  the  Cow  Head  Group,  based 
mainly  on  graptolites  and  trilobites,  shows  that  several  conglomerate  horizons  can  be  traced 
throughout  the  entire  Cow  Head  area.  Those  conglomerates  in  the  most  north-easterly  exposures 
are  thickest  and  coarsest,  and  interpreted  to  have  been  deposited  closest  to  source.  The  most 
proximal  sections  of  Stearing  Island  and  Lower  Head  are  composed  almost  entirely  of  conglomerate 
with  only  narrow  interbeds;  one  boulder  at  Lower  Head  is  200  m across  (Kindle  and  Whittington, 
1958).  The  distal  sections  such  as  that  at  Green  Point  are  mainly  shale  and  thin-bedded  limestone; 
here  the  conglomerates  are  thin  with  only  small  clasts  up  to  20  cm  diameter. 

The  proximal  sections  in  the  Cow  Head  Group  were  originally  upslope  from  the  more  distal,  and 
this  may  have  controlled  the  distribution  of  graptolites  to  some  extent.  A noticeable  feature  of  the 
distal  section  is  the  development  of  red,  bioturbated  shales  in  the  late  Tremadoc  and  Arenig, 
although  at  Cow  Head  itself  the  only  heavily  oxidized  sediments  present  are  found  in  a 3-3  m thick 
greenish  dolostone  interval  at  the  Tremadoc-Arenig  boundary.  The  overall  colour  change  in  Arenig 
shale  interbeds,  from  dominantly  green  and  black  proximally  to  almost  entirely  red  in  the  more 
distal  sections,  suggests  an  oxygen  minimum  upslope,  with  increased  ventilation  in  deeper  waters 
as  found  at  the  present  time  (see  James  and  Stevens  1986).  The  ubiquitous  red  strata  across  the 
Tremadoc-Arenig  boundary  must,  however,  reflect  important  changes  in  the  structure  of  at  least 
the  western  reaches  of  the  Iapetus  Ocean,  and  may  be  of  global  significance  (Stevens  in  prep.).  It 
is  possible  that  a stratified  Cambrian  ocean  with  anoxic  bottom  waters  changed  into  a mixed  ocean 
with  oxygenated  bottom  waters  during  the  Tremadoc,  perhaps  as  a result  of  the  glacial  event 
postulated  by  Fortey  and  Morris  (1982).  Such  a change,  particularly  if  it  occurred  during  the 
Tremadoc-Arenig  boundary  interval,  may  well  have  influenced  the  course  of  graptolite  evolution 
in  a similar  fashion  to  the  extinction  and  radiation  event  during  the  late  Ordovician  (Barnes  and 
Williams  1990). 

Stratigraphic  nomenclature  of  the  Cow  Head  Group 

The  earliest  workers  who  studied  the  rocks  of  western  Newfoundland,  namely  Richards,  Billings 
and  Logan  (in  Logan  1863),  correlated  the  Cow  Head  strata  with  similar  rocks  in  Quebec, 
particularly  with  those  at  Levis.  Logan  (1863)  placed  the  Cow  Head  Group  in  his  Division  P. 
Schuchert  and  Dunbar  (1934)  concluded  that  the  Cow  Head  was  in  part  a tectonic  breccia  of  middle 
Ordovician  age.  Kindle  and  Whittington  (1958),  following  the  lead  given  by  Johnson  (1941), 
recognized  that  the  strata  represented  a sequence  of  sediments  with  an  orderly  stratigraphy  and  that 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


5 


the  breccias  were  part  of  the  package,  rather  than  being  later,  tectonically-derived  material.  They 
used  a sequence  of  numbered  ‘Beds’  to  describe  the  Cow  Head  section.  These  are  not  beds  in  the 
usual  sedimentological  sense,  nor  do  they  conform  to  formal  lithostratigraphic  convention  as 
recognized  internationally.  Rather  they  are  hybrid  biostratigraphic/lithostratigraphic  units  defined 
on  their  fossil  content  and  gross  overall  lithology.  They  are,  however,  convenient  to  use  and  were 
extended  to  all  parts  of  the  Cow  Head  Group  by  James  and  Stevens  (1986).  Strata  yielding  a late 
Tremadoc  graptolite  fauna  occur  in  the  upper  part  of  Bed  8 (Text-figs  2 and  3),  and  are  here 
assigned  to  the  Aorograptus  victoriae  Zone.  The  base  of  this  zone  is  as  yet  undefined,  but  the  top 
is  marked  by  the  appearance  of  graptolites  indicative  of  the  early  Arenig  T.  approximate  Zone  at 
the  base  of  Bed  9 (Williams  and  Stevens  1988a).  The  more  formal  lithostratigraphic  nomenclature 
proposed  by  James  and  Stevens  (1986)  shows  correlation  with  faunal  changes  at  the 
Tremadoc-Arenig  boundary  only  in  the  more  proximal  sections  (e.g.  James  and  Stevens  1986,  fig. 
43),  where  it  lies  at  the  boundary  between  the  underlying  Stearing  Island  Member  and  overlying 
Factory  Cove  Member  of  the  Shallow  Bay  Formation. 


WESTERN  BROOK 
POND  (NORTH) 


MARTIN  POINT 
(NORTH) 


text-fig.  3.  Lithological  logs  through  the  Cow  Head  Group  for  the  Tremadoc-Arenig  boundary  interval  at 
Western  Brook  Pond,  Martin  Point  and  Green  Point,  indicating  graptolitic  horizons  (after  James  and  Stevens, 

1986). 


Correlation  with  other  sequences 

Full  discussion  of  correlation  between  graptolitic  zonal  schemes  of  the  early  Ordovician  was  given 
by  Cooper  (19796).  Since  that  time,  additional  sections  have  been  studied;  we  therefore  include  an 


6 


PALAEONTOLOGY,  VOLUME  34 


COW  HEAD 
W.  NFL  D 


P.  fruticosus 


T . akzharcnsis 


T.  approximatus 


A.  vlctoriae 


zones  not 
yet  defined 


VICTORIA 
AUSTRALIA  g 

Be4 

T.  fruti.  (3  stipe  > 

Be3 

T.  fruti.  (3  & 4) 

Be2 

T.  fruticosus  (4) 

Bel 

T.  fruticosus  & 
T.  approximatus 

La  3 

T.  approximatus 

La2 

A.  victoriae 

Lai. 5 

Pslgraptus  <& 
Cionograptus 

Lai 

D.  scltulum  & 
Anisograptus 

NEW  ZEALAND 


T.  fruticosus 


T.  approximatus 


CANADIAN 
CORDILLERA  J 


T.  fruticosus 


T . approximatus 


no  fauna 
recorded 


T.  fruticosus 


T.  approximatus 


C.  flexills  - 
A.  vlctoriae 


Anlsograptus  - 
Staurograptus 


CENTRAL 
GREAT  BRITAIN 


AlAIAkvx 

S.  pusllla 


D.  f.  flabelli- 
forme 


OSLO 

NORWAY 


Ddymograptus 

Beds 


Ceratopyge 

Beds 


Dictyonema 

Beds 


HUNNEBERG 
SWEDEN  _ 


no  fauna 
recorded 


T.  approximatus 


T.  phyllo- 
graptoides 


no  fauna 
recorded 


hunj;ang 

CHINA 


no  fauna 
recorded 


Adeiograptus  - 
Cionograptus 


text-fig.  4.  Correlation  of  the  late  Tremadoc-early  Arenig  graptolite  zones  of  the  Cow  Head  Group  with  other 
sequences  (data  based  largely  on:  1- Williams  and  Stevens  1988a  and  this  paper;  2-VandenBerg  1981; 
3 - Cooper  1979a;  4 - Lenz  and  Jackson  1986;  5 - Berry  1960;  6 - Stubblefield  and  Bulman  1929; 
7 - Monsen  1925 ; 8 - Maletz  and  Erdtmann  1987;  9 -Wang  and  Erdtmann  1986). 


updated  correlation  chart  to  include  a selection  of  these  (Text-fig.  4),  although  some  (e.g. 
Hunneberg  and  Oslo)  are  currently  under  investigation  and  detailed  biostratigraphic  discussion  is 
not  yet  possible.  For  the  purpose  of  the  present  paper,  we  merely  reiterate  the  precise  correlation 
possible  in  continuously  graptolitic  successions  across  the  Tremadoc-Arenig  boundary  interval, 
where  a rapidly  evolving  graptoloid  fauna,  as  found  in  the  A.  victoriae  Zone  in  the  Cow  Head 
Group,  becomes  extinct  and  is  then  replaced  by  the  somewhat  low-diversity  but  distinctive 
dichograptid  fauna  of  the  T.  approximatus  Zone  (see  Williams  and  Stevens  1988a).  Several 
anisograptid  genera,  including  Rhabdinopora , surprisingly  seem  to  have  been  unaffected  by  this 
evolutionary  event,  maintaining  their  relative  abundance  from  the  late  Tremadoc  through  to  the  T. 
akzharensis  Zone.  These  taxa  are,  however,  rare  in  the  succeeding  P.  fruticosus  and  later  Arenig 
zones,  where  the  fauna  is  dominated  by  dichograptids  and  sigmagraptines. 

Justification  for  employing  the  chronostratigraphic  series  ‘Tremadoc’  and  ‘Arenig’  is,  however, 
more  difficult  owing  to  the  incomplete  nature  of  original  British  sections  and  the  current  state  of  flux 
regarding  their  definition  (see  Fortey  1988).  Ongoing  biostratigraphic  studies  within  the  Cow  Head 
Group,  particularly  of  the  conodonts  and  trilobites  (see  Barnes  et  al.  1988;  Stouge  and  Bagnoli 
1988;  Williams  and  Stevens  1988/6),  are  permitting  precise  correlation  between  the  various  schemes 
at  this  level.  These  support  the  assumption  made  by  most  previous  graptolite  workers  (e.g.  Bulman 
1970;  Cooper  19796)  that  the  major  faunal  turnover  documented  at  a level  equivalent  to  the 
boundary  between  the  A.  victoriae  and  T.  approximatus  zones  lie  close  to  the  traditionally  accepted 
position  of  the  Tremadoc-Arenig  boundary. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


7 


TAXONOMIC  PROBLEMS  ASSOCIATED  WITH  LATE  TREMADOC  GRAPTOLITES 

The  earliest  graptolites  from  the  Cambrian  were  all  benthic  (see  Rickards  1977);  the  first  planktic 
graptolites  evolved  during  the  Cambrian-Ordovician  boundary  interval,  including  the  ubiquitous 
and  familiar  group  of  Rhabdinopora flabelliformis . These  Tremadoc  anisograptids  have  traditionally 
been  assigned  to  the  Dendroidea,  characterized  by  numerous,  commonly  irregular  dichotomies, 
presence  of  bithecae,  and  a sclerotized  stolon.  Fortey  and  Cooper  (1986)  produced  a revised  high 
level,  phylogenetic  classification,  in  which  they  assigned  all  nematophorous  (i.e.  planktic  and 
epiplanktic)  graptolites  to  the  Graptoloidea,  restricting  the  Dendroidea  to  benthic  genera.  For  the 
purpose  of  the  present  work,  we  accept  this  revised  notion ; consequently  all  taxa  described  herein 
are  considered  to  be  Graptoloidea. 

Bulman  (1970)  referred  all  Tremadoc  nematophorous  graptolites  to  the  Anisograptidea ; these 
were  subsequently  split  into  four  subfamilies,  the  Adelograptinae,  Anisograptinae,  Staurograptinae, 
and  Rhabdinoporinae,  although  Fortey  and  Cooper  (1986,  p.  683)  doubted  that  these  groupings 
served  any  useful,  phylogenetically- related  purpose.  Further  studies  utilizing  isolated  material  such 
as  the  present  one  are  required  before  any  additional  revision  of  high-level  classification  is  possible; 
until  that  time  we  follow  Fortey  and  Cooper  (1986)  in  using  an  undivided  family  Anisograptidae. 

Previous  publications  describing  late  Tremadoc  graptolites  have  assigned  them  to  both 
anisograptid  and  dichograptid  taxa,  for  while  some  elements  of  the  fauna  (e.g.  Rhabdinopora ) are 
clearly  identical  to  earlier  Tremadoc  taxa,  others  appear  more  similar  in  overall  rhabdosome  form 
to  ‘typically’  Arenig  dichograptids,  commonly  having  only  two  to  four  stipes  and  relatively  simple 
thecal  style.  These  species  have  been  variably  assigned  to  anisograptid  genera  such  as  Adelograptus 
and  Kiaerograptus , and  to  dichograptid  genera  including  Tetragraptus  and  Didvnwgraptus  (e.g. 
Jackson  1974;  Cooper  and  Stewart  1979).  None  of  these  previous  studies  had  the  opportunity  of 
utilizing  isolated,  three-dimensional  material  to  substantiate  deductions  made  from  flattened,  non- 
isolated species.  Most  material  described  here  from  the  Cow  Flead  Group  is  flattened,  but  three 
nodular  limestone  horizons  (at  Martin  Point  South,  Green  Point  and  St  Paul’s  Inlet)  have  yielded 
three-dimensional  graptolites  that  can  be  isolated  from  the  rock  using  acetic  acid.  These  generally 
lack  fine  detail  of  periderm  structure  owing  to  the  rather  coarse,  granular  nature  of  preservation, 
probably  related  to  partial  breakdown  of  the  organic  material  during  subsequent  burial  and  tectonic 
deformation.  A few  specimens  do,  however,  reveal  some  ultrastructure,  including  cortical  bandages 
overlying  the  fusellar  increments  (Text-fig.  5).  Most  studies  of  periderm  ultrastructure  have  been 
made  on  graptolites  of  middle  Ordovician  and  Silurian  age,  Rickards  et  al.  (1982)  recording  no 
studies  at  all  on  material  from  the  Tremadoc.  Our  material  is  thus  important  in  providing  a 
comparison  of  structures  described  from  later  taxa,  although  the  main  value  of  isolated  specimens 
from  the  Cow  Head  Group  is  in  permitting  observation  of  proximal  development.  This  has  allowed 
us  to  make  the  following  conclusions: 

1.  Whereas  presence  of  bithecae  associated  with  autothecae  is  variable,  all  taxa  from  this  interval 
possess  a sicular  bitheca.  A sicular  bitheca  has  never  been  recorded  from  any  Arenig  dichograptid 
or  sigmagraptine  species,  although  it  is  apparently  present  in  all  earlier  Tremadoc  anisograptids  (see 
Rickards  1975,  1977). 

2.  With  the  exception  of  the  sicular  bitheca,  proximal  development  of  several  late  Tremadoc 
species  is  almost  indistinguishable  from  that  of  certain  early  Arenig  dichograptid  and  sigmagraptine 
taxa  described  by  Williams  and  Stevens  (1988c/). 

3.  Although  overall  rhabdosome  form  of  a few  taxa  are  similar  to  Arenig  dichograptids  and 
sigmagraptines,  irregular  occurrence  of  delayed  dichotomies  commonly  results  in  extra  stipes  of 
variable  number.  This  contrasts  with  the  regular,  fixed  nature  of  branching  in  the  Arenig  taxa. 

4.  Genera  such  as  Rhabdinopora  and  Clonograptus  which  are  found  earlier  in  the  Tremadoc  and 
continue  through  into  the  Arenig  have  distinctive  proximal  developments  unlike  those  of  the 
majority  of  the  fauna,  and  bithecae  throughout  the  rhabdosome. 

We  consider  that  the  presence  of  a sicular  bitheca  and  irregular  dichotomous  branching  does  not 
permit  the  assignment  of  any  late  Tremadoc  graptolites  to  the  Dichograptidae  or  Sigmagraptinae, 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  5.  SEM  micrographs  showing  details  of  ultrastructure  on  isolated  metasicula  of  Kiaerograptus 
bulmani  (Thomas,  1973),  GSC  87446,  SPI43  (complete  specimen  figured  PI.  3,  fig.  12).  a,  cortical  bandages, 

x 110.  b,  fusellar  increments,  x 110. 


unless  the  traditionally  accepted  views  of  these  high-level  classifications  is  significantly  modified.  All 
taxa  described  herein  are  therefore  assigned  to  existing  or  new  anisograptid  genera.  It  does, 
however,  seem  likely  that  several  late  Tremadoc  genera  give  rise  to  Arenig  forms  through  loss  of 
bithecae  and  the  fixing  of  dichotomous  branching,  perhaps  suggesting  a polyphyletic  origin  for  the 
dichograptids  and  sigmagraptines.  This  will  be  the  subject  of  a future  study  incorporating  both 
Tremadoc  and  Arenig  material,  and  is  outside  the  scope  of  the  present  paper. 


SYSTEMATIC  PALAEONTOLOGY 

Descriptive  nomenclature  employed  conforms  to  that  of  Bulman  ( 1970),  Cooper  and  Fortey  (1982) 
and  Williams  and  Stevens  (1988a).  Particular  note  should  be  made  of  the  term  Tutellum\ 
introduced  by  Williams  and  Stevens  (1988a,  p.  20)  to  describe  the  ‘lip’  or  ‘spoon-shaped’  process 
found  at  the  sicular  aperture  of  many  Ordovician  graptolites  on  the  side  of  th  1 1 (cf  the  virgella, 
which  is  a spine).  The  acetate  overlay  technique  described  by  Williams  and  Stevens  (1988a),  p.  23) 
was  employed  to  assist  in  distinguishing  species  and  in  comparing  isolated  specimens  with  flattened 
material. 

Line  drawings  were  made  whilst  using  a Wild  M5A  microscope  with  ‘camera  lucida'  attachment. 
Light  photographs  of  isolated  and  non-isolated  material  were  taken  with  a Wild  M400 
photomicroscope,  using  fibre-optic  fight  source  and  with  slabs  immersed  in  95%  ethanol.  Scanning 
electron  micrographs  were  taken  using  a Hitachi  S570  with  a 120  film  back. 

All  figured  specimens  are  housed  in  the  collections  of  the  Geological  Survey  of  Canada,  Ottawa 
(GSC).  Specimen  localities  and  horizons  in  the  systematic  section  are  referred  to  in  abbreviated 
form;  collected  sections  (see  Text-fig.  I and  Williams  and  Stevens  1988a)  are  the  ‘Ledge’  on  the 
Cow  Head  Peninsula  (CHN),  St  Paul's  Inlet,  North  Tickle  (SPI),  Western  Brook  Pond,  north 
section  (WBN),  Martin  Point,  north  and  south  sections  (MPN  and  MPS),  and  Green  Point  (GP). 
Numbered  intervals  refer  to  those  used  in  Text-figures  2 and  3. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


9 


Order  graptoloidea 
Family  anisograptidae  Bulman,  I960 
Genus  kiaerograptus  Spjeldnaes,  1963 

Type  species.  Didymograptus  kiaeri  Monsen,  1925,  pp.  172-175,  pi.  2,  figs  9,  10,  12-14,  16,  pi.  4,  figs  6-8.  By 
original  designation. 

Diagnosis  (revised).  Rhabdosome  horizontal  or  declined,  with  two  primary  stipes,  one  or  both  of 
which  may  dichotomise  at  the  second  thecal  pair  to  produce  three  or  four  stipes.  Autothecae  simple 
or  with  sigmoidal  curvature,  prothecal  folds  occasionally  present.  Sicula  with  bitheca;  other 
bithecae  present  in  early  forms,  apparently  absent  in  later  taxa. 

Remarks.  The  definition  of  Kiaerograptus  was  revised  by  Bulman  (1970)  and  by  Cooper  and  Stewart 
(1979);  the  description  of  K.  quasimodo  by  Rushton  (1981)  and  of  taxa  in  the  present  study 
necessitate  a broadening  of  the  understanding  to  include  rhabdosomes  with  more  than  two  stipes 
as  originally  defined. 

Further  revision  might  permit  restriction  of  the  genus  to  include  only  taxa  with  sigmoidally 
curved  thecae  and  prothecal  folds,  as  found  in  K.  kiaeri . K.  quasimodo.  and  the  two  new  species 
erected  in  the  present  study  (K.  undulatus  and  K.  magnus).  This  morphological  feature  is,  however, 
often  difficult  to  recognize  in  flattened  material,  and  apparent  folding  of  the  dorsal  margin  is 
sometimes  a post-mortem  effect  related  to  diagenetic  flattening. 

All  species  included  within  Kiaerograptus  from  western  Newfoundland  have  similar  proximal 
development,  but  show  some  variation  in  thecal  style;  none,  however,  possesses  any  bithecae  other 
than  that  of  the  sicula,  and  possibly  at  the  dichotomies  of  first  order  stipes.  Species  from  earlier  in 
the  Tremadoc,  such  as  K.  kiaeri  and  K.  quasimodo  have  bithecae  associated  with  autothecae 
throughout  much  of  the  rhabdosome,  and  a gradual  reduction  in  bithecae  would  probably  be 
documented  if  a continuous  stratigraphic  succession  of  taxa  could  be  found. 


Kiaerograptus  pritchardi  (T.  S.  Hall,  1899) 

Plate  1,  fig.  1;  Text-fig.  6a-l 

1899  Didymograptus  pritchardi.  n.  sp.;  T.  S.  Hall,  p.  167,  pi.  17,  figs  7 and  9;  pi.  19,  figs  8 and  10. 
1938 b Didymograptus  pritchardi  T.  S.  Hall;  Harris  and  Thomas,  pi.  1,  fig.  13. 

I960  Didymograptus  pritchardi  T.  S.  Hall;  Thomas,  pi  1,  fig.  14. 

71962  Didymograptus  tenuiramis  sp.  nov. ; Obut  and  Sobolevskaya,  pp.  84—85,  pi.  5,  fig.  3. 

1966  Didymograptus  pritchardi  T.  S.  Hall;  Berry,  pp.  429^430,  pi.  45,  fig.  1 ; pi.  46,  fig.  1 ; pi.  47,  figs 
1 and  2. 

1974  Didymograptus (?)  stelcki  n.  sp. ; Jackson,  pp.  52-53,  pi.  5,  figs  5 and  7;  text-fig.  la,  b. 
non  1974  Kiaerograptus  pritchardi  (T.  S.  Hall);  Jackson,  p.  51,  pi.  5,  fig.  3;  text-fig.  2a.  c.  d (=  A.? 
fHiformis  sp.  nov.). 

19796  Kiaerograptus  cf.  pritchardi  (T.  S.  Hall);  Cooper,  fig.  5a. 
non  1982  Kiaerograptus  pritchardi  (T.  S.  Hall);  Gutierrez-Marco,  fig.  2/(=  K.  taylori). 

Type  specimen  (designated  Berry  1966,  p.  429).  The  lectotype  is  Nat.  Mus.  Victoria  No.  P14238,  figured  by  T. 
S.  Hall  (1899,  pi.  17,  fig.  7),  from  La2  near  Lancefield,  Victoria,  Australia. 

Diagnosis  (revised,  incorporating  Berry’s  redescription  of  type  material).  Rhabdosome  with  two  (or 
occasionally  more)  long,  slender,  gently  declined  stipes,  straight  or  dorsally  convex,  widening 
rapidly  from  04-0-6  mm  proximally  to  a maximum  of  0 5-0-9  mm.  Sicula  inclined,  10-1-5  mm  long, 
0-25-0  3 mm  wide  at  aperture.  Autothecae  number  9-9-5  in  10  mm,  overlapping  two-fifths  to  one 
half  of  their  total  length,  inclined  at  about  10°  to  dorsal  margin.  Bithecae  apparently  absent  except 
for  sicular  bitheca. 


10 


PALAEONTOLOGY.  VOLUME  34 


text-fig.  6.  Kiaerograptus  pritchardi  (T.  S.  Hall.  1899),  GP38,  all  x 5 except  a ( = x 10).  a and  b,  GSC  87381. 
c,  GSC  87393.  d,  GSC  87390.  e,  GSC  87412.  f,  GSC  87383  (also  figured  PI.  1,  fig.  I).  g,  GSC  87368.  H,  GSC 
87378.  i,  GSC  87411.  j,  GSC  87399.  k,  GSC  87406.  l,  GSC  87407. 


EXPLANATION  OF  PLATE  I 

Fig.  1.  Kiaerograptus  pritchardi  (T.  S.  Hall,  1899).  GSC  87383,  GP38,  x 10  (also  figured  Text-fig.  6f). 

Figs  2-4.  Kiaerograptus  undulatus  sp.  nov.  MPS42C,  x 10.  2,  GSC  87286.  3,  GSC  87330  (also  figured  Text-fig. 
8o).  4,  GSC  87327. 

Figs  5-7.  Kiaerograptus  magnus  sp.  nov.  GP38,  x 10.  5,  GSC  87388.  6,  GSC  87331.  7,  GSC  87361  (also  figured 
Text-fig.  8n). 

Figs  8 and  9.  Kiaerograptus  bulmani  (Thomas,  1963).  MPS42C,  x 5.  8,  GSC  87329.  9,  GSC  87317. 

Figs  10-16.  Paratemnograptus  isolatus  gen.  et  sp.  nov.  10,  GSC  87375,  GP38,  x 10.  1 1,  GSC  87315,  MPS42C, 
x 10.  12,  GSC  87287,  CHN8.30,  x 5.  13,  GSC  873846,  detail  of  distal  branching,  GP38,  x 5.  14,  GSC  87288, 
CHN8.30,  x 2.5.  1 5,  GSC  87385,  GP38,  x2-5.  16,  GSC  87289,  CHN8. 30,  x 5. 


PLATE  1 


WILLIAMS  and  STEVENS,  Kiaerograptus , Paratemnograptus 


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PALAEONTOLOGY,  VOLUME  34 


Material  and  localities.  Many  flattened,  non-isolated  specimens  from  GP38;  others  from  MPN17A,  17B.  One 
possible  poor  isolated  specimen  from  MPS42C. 

Description.  The  rhabdosome  consists  of  two  slender  stipes  occasionally  reaching  over  35  mm  long;  second 
order  branching  has  not  been  observed  in  our  material.  The  stipes  are  0- 3-0-5  mm  (commonly  0-4  mm)  wide 
at  t h 1 1 . increasing  only  slightly  to  a maximum  0-5  mm  (cf.  type  material).  Narrow  widths  are  probably  due  to 
preservation  in  oblique  orientation,  the  larger  measurements  probably  being  more  representative  of  the  true 
widths. 

The  sicula  is  TO-1 T 5 mm  long  (cf.  I -4  mm  for  type  material),  is  usually  inclined  rather  then  perpendicular 
to  the  stipes,  and  has  a gentle  convex  curvature  with  respect  to  the  rutellar  margin.  The  aperture  shows  a 
pronounced  rutellum  and  is  typically  0-25  mm  wide.  Thl 1 presumably  buds  from  the  prosicula,  growing  down 
along  the  rutellar  margin  for  0-75-0-85  mm  before  turning  sharply  out  and  growing  slightly  downwards  for  the 
remainder  of  its  0-6-0-8  mm  length.  The  base  of  the  rutellar  margin  of  the  sicula  is  left  free  for  0-15-0-4  mm 
(commonly  0-2  mm),  whereas  the  ventral  wall  of  thl1  subtends  an  angle  of  60-80°  with  the  sicular  axis.  The 
sicular  bitheca  has  not  been  observed  unequivocally,  but  by  comparison  with  other  taxa  is  almost  certainly 
present.  One  specimen  appearing  to  show  a sicular  bitheca  reveals  it  to  extend  only  slightly  beyond  the  point 
where  the  ventral  wall  of  thl1  diverges  from  the  sicula,  probably  explaining  its  cryptic  form. 

Thl2  buds  from  thl1  high  on  the  reverse  side,  growing  initially  across  the  sicula  in  an  almost  horizontal 
direction  before  turning  down  to  run  along  the  antirutellar  margin.  It  remains  in  contact  with  this  margin  until 
the  sicular  aperture  is  reached,  at  which  point  thl2  bends  abruptly  out,  subtending  an  angle  of  50-60°  with  the 
sicular  axis.  This  angle  is  maintained  for  0-6-0-9  mm  until  the  aperture  is  reached. 

Remaining  autothecae  are  almost  straight,  inclined  at  10-15°  with  the  dorsal  stipe  margin,  but  with  a slightly 
concave  ventral  wall  and  gently  flared  aperture  in  most  specimens.  Occasionally,  however,  the  ventral  wall  is 
straight;  it  is  possible  that  the  flaring  is  a preservational  artefact  related  to  differential  lateral  spread  on 
flattening.  Apertures  are  simple  but  deep,  occupying  one  half  to  two-thirds  of  total  stipe  width.  Thecal  overlap 
represents  a little  under  one  half  total  thecal  length,  while  thecal  density  is  an  almost  constant  8-10  in  10  mm 
throughout  the  rhabdosome.  Autothecal  length  appears  to  be  related  to  size  of  rhabdosome,  but  it  is  unclear 
whether  thecal  growth  is  continuous  throughout  astogeny  as  demonstrated  for  several  Arenig  dichograptids 
by  Williams  and  Stevens  (1988a).  Bithecae  have  not  been  observed  apart  from  that  of  the  sicula,  and  it  is 
unlikely  that  they  existed. 

Remarks.  Erdtmann  et  al.  (1987)  referred  K.  pritchardi  to  their  new  genus  Paradelograptus ; this 
genus  is,  however,  characterized  by  slender  thecae  similar  to  Adelograptus  and  Kinnegraptus  and 
lacks  a sicular  bitheca. 

K.  pritchardi  appears  to  be  a well-defined,  consistent  species  with  little  variation  in  rhabdosome 
form  and  dimensions,  in  contrast  to  most  other  coeval  taxa.  It  is  easily  separated  from  these  by  its 
distinctive  proximal  region.  The  Newfoundland  representatives  of  K.  pritchardi  have  rather  smaller 
dimensions  than  those  recorded  by  Berry  (1966)  for  the  type  specimens.  Berry  recorded  proximal 
widths  of  07-08  mm  widening  to  a maximum  0-8-0-9  mm  in  his  text  descriptions,  but  measurements 
from  his  illustrations  and  Cooper’s  (1979a,  fig.  17/c)  figure  of  the  lectotype  demonstrate  proximal 
widths  of  0-6  mm.  As  noted  above,  thecal  length  (and  consequently  stipe  width)  appears  to  have 
increased  during  growth  of  the  rhabdosome.  As  the  type  specimens  have  much  longer  stipes  than 
our  specimens,  stipe  widths  between  the  two  populations  are  considered  to  be  compatible,  while 
thecal  densities  are  identical.  The  length  of  the  sicula  does,  however,  appear  to  be  consistently  longer 
in  the  type  material  (1-4  mm)  than  in  the  Newfoundland  specimens  (1-0-1-15  mm). 

The  single  specimen  of  Didymograptus  tenuiramis  figured  by  Obut  and  Sobolevskaya  (1962)  is 
poorly  preserved  and  seems  to  have  suffered  tectonic  deformation.  It  does,  however,  appear  very 
similar  to  K.  pritchardi  and  is  here  tentatively  referred  to  this  species.  Although  Obut  and 
Sobolevska  (1962,  fig.  4)  refer  the  interval  yielding  D.  tenuiramis  to  earliest  Arenig,  the  associated 
assemblage  could  equally  well  be  placed  in  the  late  Tremadoc  as  it  contains  ‘ Temnograptus ’ species 
and  predates  the  first  occurrence  of  T.  approximatus. 

Specimens  from  the  Yukon,  northern  Canada  which  Jackson  (1974)  referred  to  a new  species 
Didymograptus (?)  stelki , agree  even  more  closely  with  the  Australian  types  of  K.  pritchardi  than 
those  from  Newfoundland,  and  we  have  no  hesitation  in  assigning  them  to  this  species. 

Most  of  our  specimens  of  K.  pritchardi  originate  from  Green  Point,  where  the  late  Tremadoc 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


13 


interval  is  represented  by  a succession  of  fine-grained,  fissile  shales  deposited  in  a rather  deeper, 
more  distal  environment  than  elsewhere  in  the  Cow  Head  Group.  This  distribution  may  be  related 
to  original  environmental  restraints,  or  may  be  due  to  poor  preservation  in  rather  coarser  lithologies 
elsewhere.  A similar  problem  exists  for  slender  Arenig  graptoloids  in  the  Cow  Head  group, 
Kinnegraptus  and  Adelograptus  being  largely  restricted  to  the  more  distal,  fine-grained  facies, 
deposited  in  deeper  water. 


text-fig.  7.  Kiaerograptus  cf.  K.  taylori  (T.  S.  Hall,  1899),  x 5.  a d,  GP38;  a,  GSC  87369;  b,  GSC  87386;  c, 
GSC  87392;  d,  GSC  87410.  e-g,  MPS42C ; e,  GSC  87356;  F,  GSC  87357;  g,  GSC  87358. 


Kiaerograptus  cf.  K.  taylori  (T.  S.  Hall,  1899) 

Text-fig.  7a-g 

cf.  1899  Didymograptus  taylori , n.  sp.;  T.  S.  Hall,  pp.  167-168,  pi.  17,  figs  1 1 and  12. 
cf.  1960  Didymograptus  taylori  T.  S.  Hall;  Thomas,  pi.  I,  fig.  15. 

Material  and  localities.  Seven  flattened,  non-isolated  specimens  from  GP38  and  MPS42C. 

Description.  The  rhabdosome  is  composed  of  two  stipes  up  to  25  mm  long,  with  a deflexed  or  declined  form 
and  separated  by  an  angle  of  90-120°.  They  measure  0-6-0-8  mm  wide  at  the  first  thecal  aperture;  the  larger 
width  is  found  in  specimens  with  longer  thecal  lengths  and  higher  inclinations  to  the  dorsal  stipe  wall,  but  may 
be  related  to  lateral  spread  in  some  instances.  The  stipes  soon  attain  their  maximum  width  of  10  mm,  which 
is  then  maintained  throughout  the  rhabdosome. 

The  sicula  is  a consistent  L5-L6  mm  long,  with  an  apertural  width  of  0-3-0-45  mm.  It  is  initially  straight, 
but  has  a convex  curvature  with  respect  to  the  rutellar  margin  over  the  distal  0-5  mm.  A short  nema  is 
occasionally  present;  the  sicular  bitheca  has  not  been  seen,  but  is  almost  certainly  present.  Proximal 


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PALAEONTOLOGY,  VOLUME  34 


development  has  not  been  observed,  but  is  probably  similar  to  other  late  Tremadoc  graptolites  with  a 
prosicular  origin  for  th  1 1 . With  the  exception  of  the  sicula,  bithecae  appear  to  be  absent. 

Autothecae  have  a low  initial  inclination  of  about  10°  to  the  dorsal  margin,  but  this  increases  throughout 
their  length  to  reach  a maximum  of  3(MK)°  near  the  aperture.  Thecal  length  is  somewhat  variable;  overlap  is 
about  one  half  of  total  length  in  early  thecae,  reducing  to  about  one  third  distally.  Free  ventral  thecal  margins 
are  markedly  concave,  particularly  towards  the  apertures  which  occupy  one  third  to  one  half  of  total  stipe 
width,  giving  a markedly  denticulate  appearance  to  the  ventral  stipe  margin.  Thecal  density  is  somewhat 
variable  8-10  in  10  mm  proximally,  but  reduces  to  a constant  8 in  10  mm  distally. 

Remarks.  Although  the  generic  assessment  of  K.  taylori  has  been  discussed  relatively  recently  (e.g. 
by  Cooper  and  Stewart  1979,  p.  790),  no  additional  specimens  appear  to  have  been  described  since 
the  original  description  by  T.  S.  Hall  in  1899.  From  his  remarks  (1899,  p.  168)  it  seems  that  Hall 
possessed  more  than  the  one  specimen  illustrated;  unfortunately  there  are  several  discrepancies 
between  his  written  description,  figure  at  natural  size  and  the  illustration  recorded  as  x 3 
magnification.  Thomas  (1960,  fig.  15)  has  since  provided  a rather  clearer  figure  of  the  specimen  at 
natural  size. 

Because  of  Hall's  poor  original  description  and  lack  of  revisions  using  the  type  material, 
assignment  of  our  Newfoundland  specimens  cannot  be  certain  and  we  therefore  refer  them  to  K.  cf. 
taylori.  This  species  is  unlike  any  other  taxa  from  the  late  Tremadoc  of  the  Cow  Head  Group,  with 
the  exception  of  K.  pritchardi , from  which  it  differs  by  its  longer  sicula,  more  robust  form,  steeply 
inclined  stipes  and  narrower  thecal  apertures.  Bulman  (1950)  compared  his  new  species 
Didymograptus  primigenius  with  D.  taylori ; the  overall  dimensions  and  rhabdosome  form  of  this 
taxon  from  the  middle  Tremadoc  of  Quebec  are,  however,  closer  to  those  of  K.  pritchardi.  It  is 
distinguished  from  this  species  by  its  more  steeply  inclined  thecae  and  higher  thecal  density  of  1 1 
in  10  mm. 


Kiaerograptus  undulatus  sp.  nov. 

Plate  1,  figs  2-4;  Plate  3,  figs  1 and  2;  Text-fig.  8a-h 

cf.  1937  Didymograptus  norvegicus , n.  sp.;  Monsen,  pp.  176-177,  pi.  2,  figs  7 and  8;  pi.  4,  figs  4 and  5; 
fig.  6. 

1983  ? Kiaerograptus  sp.  cf.  K.  quasimodo  Rushton;  Henderson,  p.  155,  fig.  5 g-j. 

Derivation  of  name.  From  undulatus  (Latin)  meaning  'wavy',  referring  to  the  folded  dorsal  stipe  margin. 

Type  specimen.  The  holotype  is  GSC  87413,  from  Green  Point  (GP40).  Figured  Text-figure  8a. 

Diagnosis.  Small  rhabdosome  composed  of  four  (occasionally  two  or  three)  slightly  declined, 
radiating  stipes,  measuring  0-7-0-8  mm  wide  proximally  with  rapid  increase  to  the  maximum 
TO  mm.  Sicula  T5-T8  mm  long,  almost  straight,  with  apertural  width  of  0-25  mm.  Prominent 
sicular  bitheca  filling  much  of ‘notch'  of  basal  rutellar  margin.  Autothecae  strongly  curved,  with 
strong  prothecal  folds,  wide  apertures  occupying  one  half  of  total  stipe  width  and  numbering  9-10 
in  10  mm.  Many  or  all  autothecae  with  bithecae  opening  into  large  apertures. 

Material  and  localities.  Fifteen  flattened,  non-isolated  specimens  from  GP38,  40;  MPS42C;  CH8-34.  One 
isolated,  three-dimensional  specimen  from  MPS42C. 

Description.  The  species  is  known  only  from  small  proximal  fragments  with  stipes  up  to  8 mm  long.  The 
rhabdosome  typically  consists  of  four,  gently  declined,  radiating  stipes,  formed  by  the  dichotomous  division 
of  th21  and  22.  Occasional  specimens  with  two  horizonal  stipes  considered  to  belong  to  this  species  have, 
however,  been  found.  Stipes  are  generally  0-7-0-8  mm  wide  proximally,  with  rapid  increase  to  F0  mm,  although 
a few  specimens  are  10  mm  wide  proximally.  The  dorsal  stipe  margin  is  characterized  by  pronounced  prothecal 
folds,  although  these  are  less  conspicuous  in  more  poorly  preserved,  flattened  material. 

The  sicula  is  F5-F8  mm  long  and  almost  straight  throughout  its  entire  length,  with  an  apertural  width  ot 
0-25  mm.  Proximal  development  has  not  been  observed  clearly,  but  evidently  agrees  with  that  of  other  late 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GR APTOLITES 


15 


text-fig.  8.  a-h,  Kiaerograptus  undulatus  sp.  nov.,  a-g  x 5,  it  x 2 5.  a,  GSC  87413,  Holotype,  GP40.  b,  GSC 
87296,  CHN8.34.  c,  GSC  87318.  MPS42C.  d,  GSC  87328,  MPS42C.  E,  GSC  87359,  MPS42C.  f,  GSC  87371, 
GP38.  G,  GSC  87414,  GP40.  h,  GSC  87322,  MPS42C.  i p,  Kiaerograptus  magnus  sp.  nov.  i-n  GP38,  x 5;  i, 
GSC  87365;  j,  GSC  87404;  k,  GSC  87363;  l,  GSC  87372;  m,  GSC  87408;  n,  GSC  87361,  Holotype  (also 
figured  PI.  1,  fig.  7).  o,  GSC  87330,  MPS42C  (also  figured  PI.  1,  fig.  3).  p,  GSC  87325,  MPS42C. 


Tremadoc  taxa.  Thl1  diverges  from  the  sicula  relatively  high,  leaving  the  basal  rutellar  margin  free  for  05- 
0-6  mm.  Much  of  this  ‘notch’  is,  however,  commonly  filled  by  the  sicular  bitheca,  giving  a more  robust  and 
‘filled-in’  appearance  to  the  proximal  region.  Thl  2 also  leaves  the  sicula  above  the  level  of  the  sicular  aperture, 
leaving  the  antirutellar  margin  free  for  01-0-2  mm. 

The  free  ventral  margins  of  thl1  and  l2  measure  TO  mm  and  0-8  mm  respectively;  both  show  pronounced 
downward  curvature  throughout  their  free  portions  and  splay  out  towards  the  apertures,  which  are  0-35-0-4 
mm  in  diameter  (half  total  stipe  width).  Th2L  and  22  are  commonly  dichotomous,  giving  rise  to  the  typically 
‘tetragraptid’  form;  in  these  specimens  thl1  and  l2  possess  bithecae  which  open  into  large  apertures  alongside 
those  of  the  autothecae  and  directly  below  the  point  of  branching.  It  is  unclear  whether  these  bithecae  are 
present  in  the  two-stiped  forms,  or  whether  they  occur  throughout  the  rhabdosome.  End-on  views  of  the  single 
isolated  specimen  suggest  that  they  are  indeed  present  in  at  least  the  succeeding  few  thecae,  unless  this  specimen 


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PALAEONTOLOGY.  VOLUME  34 


is  showing  a third-order  dichotomy.  All  autothecae  throughout  the  rhabdosome  show  the  same  characteristic 
strong  curvature,  prothecal  folds  and  wide  apertures  occupying  one  half  of  total  stipe  width.  Thecal  overlap 
is  greater  than  one  half,  while  thecal  density  is  a constant  9-10  in  10  mm. 

Remarks.  K.  undulatus  is  a very  distinctive  form  when  well  preserved  owing  to  the  sinuous  nature 
of  the  thecae,  which  gives  an  appearance  reminiscent  of  the  Arenig  sinograptids.  The  outline  of  the 
dorsal  wall  is  somewhat  variable,  from  specimens  with  strong  prothecal  folds  to  others  with  an 
almost  straight  dorsal  margin.  Although  this  may  be  partly  an  original  morphological  feature,  the 
folds  may  well  have  been  reduced  by  differential  lateral  spread  on  compaction,  as  described  for  the 
Upper  Ordovician  Dicellograptus  complanatus  Lapworth  by  Briggs  and  Williams  (1981)  and 
Williams  et  al.  (1982). 

Henderson’s  (1983)  specimens  of  K.  ? cf.  quasimodo  agree  well  with  K.  undulatus , although  they 
are  all  two-stiped  forms.  The  types  of  A'.?  quasimodo  described  by  Rushton  (1981)  from  the  middle 
or  upper  Tremadoc  subsurface  of  central  England  differ,  however,  by  their  longer  sicula  and  more 
steeply  inclined  thecae,  resulting  in  a slightly  higher  thecal  count.  Most  specimens  of  A.?  quasimodo 
were  two-stiped  forms,  although  one  possible  three-stiped  specimen  with  a higher  thecal  density  was 
recorded  by  Rushton  (1981,  fig.  3c).  K. ? quasimodo  is  clearly  similar  to  A.  undulatus  and  may  well 
represent  an  ancestral  taxon.  A.  undulatus  is  also  comparable  with  Didymograptus  norvegicus 
Monsen:  this  has  a folded  dorsal  margin  and  equivalent  thecal  densities,  but  a rather  smaller, 
inclined  sicula  14  mm  long  and  two  reclined  stipes. 

The  only  other  associated  species  with  which  A.  undulatus  may  be  confused  is  K.  bulmani  sp.  nov. 
The  latter  species  has  a much  more  slender  and  open  rhabdosome,  rather  more  gently  inclined 
thecae  with  a marginally  lower  thecal  density  of  8-9  in  10  mm,  and  seems  to  lack  the  prominent 
folded  dorsal  margin  (although  one  two-stiped  specimen  possibly  referable  to  this  species  does  have 
prothecal  folds). 


Kiaerograptus  magnus  sp.  nov. 

Plate  1,  figs  5-7;  Plate  3,  figs  4 and  7;  Text-fig.  7i-p 

Derivation  of  name.  From  magnus  (Latin)  meaning  ‘large’,  in  reference  to  the  large  and  robust  sicula  and 
proximal  region. 

Type  specimen.  The  holotype  is  GSC  87361,  from  Green  Point  (GP38).  Figured  Plate  1,  fig.  7 and  Text-figure 
8n. 

Diagnosis.  Robust  rhabdosome  with  four,  three  or  two  stipes  1-2  mm  wide  proximally.  Sicula  up  to 
2-3  mm  long,  almost  straight,  with  pronounced  rutellum  and  aperture  0 5 mm  diameter.  Autothecae 
simple,  inclined  at  3CMf0°  to  dorsal  margin,  numbering  9-10  in  10  mm.  Bithecae  apparently  lacking 
with  exception  of  large  sicular  bitheca. 

Materials  and  localities.  Ten  flattened  specimens  from  MPS42C  and  GP38.  Four  isolated,  three-dimensional 
specimens  from  SP143  and  MPS42C. 

Description.  The  rhabdosome  is  robust  with  two,  three  or  four  stipes,  F2  mm  wide  proximally  and  increasing 
rapidly  to  over  F5  mm  within  5 mm.  Only  proximal  fragments  have  been  positively  identified,  with  stipes  up 
to  6 mm  long. 

The  sicula  is  long  and  wide,  reaching  up  to  2-3  mm  long  measured  along  the  gently  convex  rutellar  margin, 
with  a conspicuous  rutellum  projecting  (F2  mm  and  long  nema  which  is  occasionally  thickened  or  lorked  (Text- 
fig.  8m,  n).  The  sicula  is  0-5  mm  diameter  at  its  aperture.  Thl1  buds  from  the  prosicula,  growing  down  in 
contact  with  the  metasicula  for  about  1 mm  before  diverging  gently  out  at  20-30°.  A large  sicular  bitheca  fills 
most  of  the  notch  left  between  the  rutellar  margin  of  the  sicula  and  ventral  wall  of  thl 1 . The  arrangement  ol 
the  sicula  and  first  theca  is  highly  symmetrical  in  young  growth  stages,  giving  an  appearance  approaching  that 
found  in  the  Arenig  genus  Isograptus.  This  symmetry  is,  however,  lost  during  astogeny,  as  thl1  continues  to 
grow  with  a free  ventral  wall  up  to  FI  mm  long. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


17 


Thl2  buds  from  high  up  th  1 1 , as  does  Th2L  It  grows  down  and  across  the  sicula,  its  ventral  wall  intersecting 
the  antirutellar  apertural  margin  of  the  sicula.  Its  original  angle  of  30°  subtended  with  the  sicular  axis  decreases 
slightly  throughout  its  distal  portion,  resulting  in  a concave  free  ventral  margin  up  to  10  mm  long. 

Remaining  development  is  similar  to  other  Kiaerograpius  taxa,  th2‘  and  22  normally  being  dichotomous, 
although  one  or  both  dichotomies  may  be  suppressed.  Remaining  autothecae  are  straight  and  inclined  at 
30-40°  to  the  dorsal  margin.  They  overlap  about  one  half  their  length,  have  simple  apertures  occupying  about 
one  half  of  total  stipe  width,  and  number  9-10  in  10  mm.  No  bithecae  have  been  observed  apart  from  that  of 
the  sicula. 

Remarks.  The  robust  proximal  region  and  large  sicula  separate  K.  magnus  from  all  other  coeval 
Kiaerograpius  species  and  give  an  appearance  reminiscent  of  Clonograptus.  However,  K.  magnus 
lacks  the  common  bithecae  characteristic , of  this  genus  during  the  late  Tremadoc,  and  appears  to 
only  have  a maximum  of  four  stipes,  although  more  complete  specimens  might  potentially  possess 
further  delayed,  dichotomous  branching.  The  forked  and  thickened  nemata  present  on  some 
specimens  are  unusual  for  graptolites  from  this  stratigraphical  interval  and  may  have  some 
taxonomic  significance. 


text-fig.  9.  a-h,  Kiaerograptus  bulmani  (Thomas,  1973).  a,  GSC  87400,  GP38,  x 10,  b,  GSC  87420,  GP40,  x 5. 
c-h,  x 2-5 ; c,  GSC  87324,  MPS42C ; d,  GSC  87339,  MPS42C ; e,  GSC  87295,  CHN8.34 ; f,  GSC  87364,  GP38 ; 
G,  GSC  87366,  GP38;  H,  GSC  87319,  MPS42C.  i,  K.  bulmani  (Thomas,  1973)7,  GSC  87323,  MPS42C,  x2-5. 


Kiaerograptus  bulmani  (Thomas,  1973) 

Plate  1,  figs  8 and  9;  Plate,  3 figs  5,  6,  8-14;  Text-fig.  9a-i 

1971  Tetragraptus  otagoensis  (Benson  and  Keble);  Erdtmann,  pp.  259-260,  pi.  33,  figs  1-3. 

1973  Tetragraptus  bulmani  sp.  nov.;  Thomas,  pp,  530-531,  pi.  2,  figs  b and  c. 

1979  Tetragraptus  bulmani  Thomas;  Cooper  and  Stewart,  p.  795,  text-fig.  8/?,  k. 

Type  specimen.  The  holotype  is  specimen  No.  64419  in  the  Mines  Department  Museum,  Melbourne.  From  the 
middle  Lancefieldian  (La2),  loc.  68,  Staurograptus  Gully,  Parish  of  Springfield,  Victoria. 


18 


PALAEONTOLOGY,  VOLUME  34 


Diagnosis  (revised,  incorporating  descriptions  by  Thomas  (1973)  and  Cooper  and  Stewart  (1979)). 
Small,  slender  rhabdosome  with  four  or  three,  radiating,  gently  declined  stipes  increasing  from 
0-4-0- 5 mm  wide  proximally  to  a maximum  0-8  mm  (0-5-0-6  mm  in  scalariform  or  oblique 
preservation).  Thecae  simple,  straight,  gently  inclined  at  about  20°  and  numbering  a constant  8-10 
in  10  mm.  Sicula  with  bitheca,  other  bithecae  apparently  lacking  except  at  dichotomies. 

Material  and  localities.  Twenty  flattened  specimens  from  CH8-34;  MPS42C;  GP38,  40.  Fifteen  isolated,  three- 
dimensional  specimens  from  SPI43,  MPS42C  and  GP38. 

Description.  The  rhabdosome  is  composed  of  four  radiating,  slender  stipes  up  to  20  mm  long.  Proximally  they 
have  a dorso-ventral  width  of  0-4-0-5  mm,  increasing  to  0-5-0-7  mm  in  5 mm  and  reaching  a maximum  of 
0-8  mm.  Stipes  are  commonly  preserved  in  oblique  or  scalariform  view,  resulting  in  rather  narrower  widths  of 
0-5-0-6  mm.  Rare  preservation  of  the  rhabdosome  in  lateral  view  reveals  the  stipes  to  be  gently  declined. 
Occasionally  one  dichotomy  is  suppressed,  resulting  in  a three-stiped  rhabdosome,  although  the  majority  of 
specimens  from  the  Cow  Head  Group  possess  four  stipes.  One  specimen  possibly  referable  to  K.  bulmani 
(Text-fig.  9i)  has  only  two,  horizontal  stipes,  suggesting  suppression  of  both  dichotomies;  this  example  however 
has  a strongly  folded  dorsal  margin  and  may  not  belong  to  this  species. 

The  sicula  is  1-4  mm  long  (but  apparently  only  1-2  mm  in  non-isolated  specimens),  measured  along  the 
rutellar  margin,  with  an  apertural  diameter  of  0-2-0-25  mm.  It  is  straight  or  almost  straight  throughout  its 
length,  with  a small  but  conspicuous  rutellum  projecting  0-08  mm  beyond  the  antirutellar,  apertural  margin. 
Thl1  buds  from  the  prosicula  on  the  rutellar  side  and  grows  down  in  contact  with  the  sicula  for  0-8-0-85  mm 
before  turning  out,  after  which  it  subtends  an  angle  of  40°  with  the  sicular  axis  for  the  remaining  0-7-0-9  mm 
of  its  length.  Th  1 1 has  an  almost  constant  diameter  of  0-2-0-23  mm  during  the  second  portion  of  its  development 
and  opens  into  a simple  aperture. 

A sicular  bitheca  is  invariably  present,  opening  at  a level  varying  from  0- 1 5 mm  above  the  point  of  divergence 
of  th  1 1 to  just  below  the  level  of  divergence.  Development  may  be  sinistral  or  dextral.  Th  1 2 buds  from  th  1 1 about 
0-5  mm  below  the  apex  of  the  sicula;  it  grows  down  and  across  at  30°  to  the  sicular  axis,  maintaining  this 
direction  of  growth  throughout  its  length.  Subsequent  development  and  branching  patterns  appear  to  be 
typically  ‘dichtograptid ’,  with  thl2,  thd1  and  th22  dichotomous  (one  or  both  branchings  may  be  suppressed). 
Bithecae  appear  to  be  absent  apart  from  that  of  the  sicula,  and  possibly  at  dichotomies  (Plate  3,  fig.  13). 

Remaining  thecae  are  simple,  straight,  gently  inclined  at  about  20°  to  the  dorsal  margin  and  have  apertures 
occupying  one  third  to  one  half  of  total  stipe  width.  Thecal  overlap  is  about  one-third,  while  thecal  density  is 
a uniform  8-10  in  10  mm  throughout  the  rhabdosome.  Rare  flattened  specimens  appear  to  exhibit  prothecal 
folds,  but  these  are  not  present  in  isolated  material.  Critical  observation  suggests  that  they  may  be  due  to  lateral 
spread  of  the  apertural  regions  during  flattening  in  oblique  or  scalariform  orientation,  apertural  walls 
becoming  visible  on  both  sides  of  the  stipe  margin  (e.g.  Text-fig.  9b,  g). 


Remarks.  K.  bulmani  is  distinct  from  other  taxa  at  this  stratigraphical  level  due  to  its  narrow  stipes 
and  widely  spaced  thecae.  Our  specimens  appear  to  agree  with  the  Australian  types  in  all  respects, 
except  in  lacking  flared  thecal  apertures.  Such  flaring  is,  however,  common  in  many  graptolites  with 
straight,  simple  thecae,  due  to  post-mortem,  differential  lateral  spread  during  flattening  of  the 
rhabdosome  and  is,  therefore,  of  no  taxonomic  importance.  K.  bulmani  differs  from  Kiaerograptus 
otagoensis  (Benson  and  Keble,  1936)  by  its  rather  narrower  stipes  and  lower  thecal  densities; 
Erdtmann’s  ( 1971 ) specimens  referred  to  K.  otagoensis  are  from  Martin  Point  and  clearly  belong  to 
K.  bulmani.  K.  bulmani  may  be  distinguished  from  K.  undulatus  sp.  nov.  by  that  species’  rather 
different  proximal  development,  wider  stipes  and  prominent  prothecal  folds.  Occasionally,  however, 
specimens  are  found  preserved  in  oblique  or  scalariform  orientation  which  could  be  assigned  to 
either  one  of  the  species. 

The  similarity  in  thecal  style  between  K.  bulmani  and  Kiaerograptus  pritchardi  (T.  S.  Hall)  was 
noted  both  by  Thomas  (1973)  and  by  Cooper  and  Stewart  (1979).  Our  isolated  and  flattened 
material  reveals  that  K.  bulmani  has  a similar  proximal  development  to  that  shown  by  both  K. 
pritchardi  and  K.  taylori , which  is  why  we  refer  that  species  to  Kiaerograptus  rather  than  retaining 
within  the  dichograptid  genus  Tetragraptus.  K.  otagoensis  is  also  similar  and  should  be  referred  to 
this  genus.  Cooper  and  Stewart  (1979)  remarked  that  K.  bulmani  was  rather  similar  to  the 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


19 


Bendigonian  (lower  Arenig)  species  Tetragraptus  harti  T.  S.  Hall.  Williams  and  Stevens  ( 1988a) 
recently  redescribed  this  taxon  from  the  D.  bifidus  Zone  of  the  Cow  Head  Group  and  transferred 
it  to  the  genus  Etagraptus.  Although  similar  in  overall  rhabdosome  form,  E.  harti  is  a true 
dichograptid  without  a sicular  bitheca,  and  any  similarity  to  K.  otagoensis  is  entirely 
hoinoeomorphic. 


Genus  paratemnograptus  nov. 

Type  species.  Paratemnograptus  isolatus  sp.  nov.  By  monotypy. 

Diagnosis.  Pauciramous,  radiate  rhabdosome  with  up  to  sixteen  stipes  arising  from  two  primary 
stipes  by  three  orders  of  widely  spaced,  delayed,  irregular,  dichotomous  branching.  Sicula  with 
bitheca.  Autothecae  gently  curved  with  moderate  inclination,  simple  apertures  and  apparently 
lacking  bithecae. 

Remarks.  Proximal  branching  conforms  to  a standard  tetragraptid  plan,  with  two  primary  stipes 
and  th2x  and  th22  dichotomous.  Subsequent  dichotomies  are  delayed  and  irregular,  many  large 
rhabdosomes  possessing  only  four  stipes.  Overall  form  may,  therefore,  be  similar  to  either 
Tetragraptus  or  Temnograptus , although  both  these  genera  are  Arenig  in  age  and  lack  bithecae. 
Paratemnograptus  further  differs  from  the  diagnosis  of  Temnograptus  given  by  Bulman  (1970, 
p.  VI 13)  in  having  irregular  dichotomous  stipe  division  and  non-denticulate  thecae.  The  type  species 
of  Temnograptus , namely  T.  multiplex  (Nicholson,  1868),  is  poorly  known  and  based  on  inadequate, 
flattened  and  deformed  material  from  an  uncertain  stratigraphic  level.  Further  work  may  ultimately 
prove  Paratemnograptus  to  be  synonymous  with  Nicholson's  genus. 


Paratemnograptus  isolatus  sp.  nov. 

Plate  1,  figs  10-16;  Plate  2,  fig.  4;  Plate  4,  figs  1-8;  Text-fig.  10a-o 

71899  Tetragraptus  decipiens,  n.  sp.;  T.  S.  Hall,  pp.  168-169,  pi.  17,  figs  13-15;  pi.  18,  figs  16-19. 
71904  Temnograptus  noveboracensis  sp.  nov.;  Ruedemann,  pp.  619-620,  pi.  5,  figs  15-20,  35,  36. 
71920  Tetragraptus  decipiens , T.  S.  Hall;  Keble,  pp.  199-200,  pi.  34,  fig.  1 a-e. 

71947  Temnograptus  noveboracensis  Ruedemann;  Ruedemann,  p.  284,  pi.  44,  figs  14—16;  pi.  45,  figs 
1-4. 

71962  Temnograptus  aff.  noveboracensis  Ruedemann;  Obut  and  Sobolevskaya,  p.  79,  pi.  3,  fig.  3. 
71966  Tetragraptus  decipiens  T.  S.  Hall;  Berry,  pp.  423-424,  pi.  44,  figs  5,  10,  11. 

71969  Tetragraptus  decipiens  T.  S.  Hall;  Bulman  and  Cooper,  pp.  215-216,  pi.  1,  figs  1-4;  fig.  3 a-c. 
71974  Clonograptus  sp.  A;  Jackson,  pp.  46^47,  text-fig.  4. 

1974  Clonograptus  sp.  B;  Jackson,  p.  47,  text-fig.  1 m.  n. 

71974  Tetragraptus  decipiens  T.  S.  Hall;  Jackson,  pp.  53-54,  pi.  5,  fig.  4. 

1979a  Temnograptus  aff.  regularis  (Tornquist,  1904);  Cooper,  p.  58,  pi.  1/;  fig.  24. 

7 19796  Tetragraptus  decipiens  T.  S.  Hall;  Cooper,  fig.  5 f. 

1979  Temnograptus  sp.;  Cooper  and  Stewart,  pp.  793-795,  text-fig.  8c. 

71979  Tetragraptus  decipiens  T.  S.  Hall;  Cooper  and  Stewart,  pp.  795-796,  text-fig.  8a,  b. 

7 1982  Temnograptus  sp. ; Gutierrez-Marco,  fig.  2k. 

Derivation  of  name.  From  isolatus  (Latin)  meaning  detached  or  separate,  in  reference  to  the  widely  spaced, 
irregular  dichotomous  branching. 

Type  specimen.  The  holotype  is  GSC  87284,  from  the  Ledge,  Cow  Head  Peninsula  (CHN8.30).  Figured  Text- 
fig.  10l. 

Diagnosis.  Large  rhabdosome  with  four  to  sixteen  slightly  flexuous,  radiating  stipes  increasing 
rapidly  from  0-8-F2  mm  wide  proximally  to  F4  mm  maximum.  Slender  sicula  with  sicular  bitheca. 


20 


PALAEONTOLOGY,  VOLUME  34 


funicle  composed  of  thl 1 and  thl2  2-5— 3-0  mm  wide.  Thecae  simple,  overlap  one  half,  thecal  density 
9-10  in  10  mm. 

Material  and  localities.  Numerous  flattened  specimens  from  CHN8.30;  MPN17B;  MPS42C;  GP38,  40.  Over 
twenty  isolated,  three-dimensional  specimens  from  SP143,  MPS42C. 

Description.  The  rhabdosome  consists  of  four  to  sixteen  long,  slightly  flexuous,  radiating  stipes  reaching  over 
70  mm  long  and  widening  rapidly  from  0-8-1  -2  mm  proximally  to  a maximum  I -4  mm  which  is  then 
maintained. 

The  sicula  is  1 -6-1-8  mm  long;  it  is  straight  throughout  its  length  and  relatively  slender,  reaching  0-2  mm 
diameter  at  the  aperture.  It  has  a small  but  conspicuous  rutellum  extending  0-1-0-15  mm  beyond  the 
antirutellar  margin.  Thl1  generally  buds  from  the  prosicula  on  the  rutellar  margin,  although  in  one  well- 
preserved  specimen  it  buds  from  the  antirutellar  side,  then  swings  immediately  across  to  the  rutellar  margin. 
Thl1  grows  down  along  the  rutellar  margin  for  0-75  mm  before  turning  outwards,  subtending  an  angle  of  40° 
with  the  sicular  axis  which  is  maintained  throughout  the  remainder  of  its  length.  The  distal  rutellar  margin  of 
the  sicula  is  left  free  for  0-25-0-3  mm.  A sicular  bitheca  buds  from  the  sicula  below  the  point  of  origin  of  thl1, 
opening  into  an  aperture  a little  above  the  point  of  divergence  of  the  ventral  wall  of  thl1  from  the  sicula. 
Development  may  be  either  right-  or  left-handed;  thl2  buds  from  thl1  above  its  point  of  deflection,  growing 
down  and  across  the  sicula  and  the  ventral  wall  of  thl2  intersects  the  base  of  the  antirutellar  sicula  margin.  Thl2 
is  dichotomous,  giving  rise  to  tfG1  and  th2'\  as  are  each  of  these  subsequent  thecae  to  give  the  typical 
‘ tetragraptid  ’ proximal  plan.  The  funicle,  consisting  of  the  first  two  thecae,  is  2- 5-3-0  mm  wide. 

Subsequent  autothecae  have  a typically  dichtograptid  appearance;  their  angle  of  inclination  with  the  dorsal 
margin  increases  from  30°  initially  to  50°  towards  the  aperture,  which  is  simple.  Thecal  overlap  is  one  half  of 
total  length,  while  apertures  occupy  one  half  to  two-thirds  of  total  stipe  width.  Bitheca  appear  to  be  lacking 
with  the  exception  of  the  sicular  bitheca.  Thecal  density  is  a uniform  9-10  in  10  mm  throughout  the 
rhabdosome. 

Remarks.  Although  the  overall  form  is  distinctive,  details  of  thecal  morphology  or  proximal 
development  are  rarely  seen  in  flattened  specimens  owing  to  common  preservation  in  scalariform 
orientation.  Most  rhabdosomes  have  only  four  stipes,  but  sufficient  specimens  have  been  found  with 
additional  distal  dichotomies  to  determine  the  variability  of  this  morphological  feature.  There  are 
no  other  associated  species  which  might  be  confused  with  P.  isolatus ; as  can  be  seen  from  the  list 
of  synonymies,  both  the  generic  and  specific  identity  of  this  taxon  have,  however,  been  problematic. 

Temnograptus  regularis  (Tornquist)  as  described  by  Tornquist  (1904)  and  Monsen  (1937) 
certainly  appears  similar,  but  both  our  material  and  that  described  by  Cooper  (1979a)  has  more 
widely  spaced  dichotomies,  more  slender  stipes  and  is  much  earlier  (late  Tremadoc  as  opposed  to 
middle  Arenig). 

Temnograptus  noveboracensis  Ruedemann  was  based  entirely  on  distal  stipe  fragments  and  is, 
therefore,  not  a strictly  valid  taxon.  Ruedemann  (1947,  pi.  44,  figs  14-16)  did,  however,  figure  three 
fragments  from  the  Cow  Head  Group  and  these  are  likely  to  belong  to  P.  isolatus. 

Tetragraptus  decipiens  T.  S.  Hall  has  been  recorded  previously  from  the  late  Tremadoc  and  early 


EXPLANATION  OF  PLATE  2 

Fig.  1.  Aorograptus  victoriae  (T.  S.  Hall,  1899).  GSC  87309,  MPS42C,  x2-5  (also  figured  Text-fig.  1 1 L). 

Figs  2 and  3.  Adelograptus  cf.  A.  tenellus  (Linnarsson,  1871).  2,  GSC  87376,  GP38,  x 5.  3,  GSC  87307, 

MPN17B,  x 10. 

Fig.  4.  Paratemnograptus  isolatus  gen.  et  sp.  nov.  GSC  87362,  GP38,  x 10  (also  figured  Text-fig.  10b). 

Fig.  5.  Clonograptus  sp.  B.  GSC  87314,  MPS42C,  x 2-5  (also  figured  Text-fig.  I5j). 

Fie.  6.  Clonograptus  sp.  A.  GSC  87354,  MPS42C,  x 2-5. 

Figs  7-11.  Rhabdinopora  sp.  7,  GSC  87308,  MPNI7B,  x 10.  8,  GSC  87290,  CHN8.30,  x 5.  9,  GSC  87291. 
CHN8.30.  x 2-5.  10,  GSC  87396,  GP38,  x 5.  11.  GSC  87292,  CHN8.30,  x2-5.  13,  GSC  87293,  CHN8.30, 
x 2-5. 

Fig.  12.  Dendroid  indet.,  distal  fragment.  GSC  87316,  MPS42C,  x 5. 


PLATE  2 


WILLIAMS  and  STEVENS,  Late  Tremadoc  graptolites 


22 


PALAEONTOLOGY,  VOLUME  34 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GR APTOLITES 


23 


Arenig  of  Australasia  and  North  America;  the  type  specimens  are,  however,  poor  and  are  only 
juveniles  (see  Berry  1966).  The  only  description  of  T.  decipiens  including  anything  more  than 
juveniles  was  by  Keble  (1920).  The  taxonomic  affinities  of  T.  decipiens  were  discussed  by  Williams 
and  Stevens  (1988#),  who  concluded  that  many  lower  Arenig  specimens  were  probably  juvenile 
representatives  of  T.  approximatus  approximatus  Nicholson.  We  furthermore  believe  that  the 
Tremadoc  examples  of  T.  decipiens  are  probably  juvenile  representatives  of  our  new  species  P. 
isolatus , in  which  case  T.  decipiens  would  be  a senior  synonym.  The  dimensions  of  the  sicula  given 
by  Berry  (1966)  for  the  types  of  T.  decipiens  are,  however,  greater  than  those  for  P.  isolatus ; he 
recorded  that  the  sicula  was  1 -9-2-4  mm  long  and  0-4-0- 5 mm  wide  at  the  aperture  (cf.  1 -6—  1 -8  mm 
long  and  0-2  mm  wide  for  P.  isolatus). 

Until  a better  population  of  T.  decipiens  is  collected  from  the  type  locality,  including  large,  mature 
rhabdosomes  and  specimens  in  which  the  presence  or  absence  of  a sicular  bitheca  can  be  determined, 
the  synonymy  with  P.  isolatus  must  remain  questionable. 


Genus  aorograptus  nov. 

Derivation  of  name.  From  aoros  (Greek),  meaning  pendulous,  hanging  or  waving,  in  reference  to  the  pendent 
nature  of  the  rhabdosome. 

Type  species.  Bryograptus  victoriae  T.  S.  Hall,  1899,  p.  165,  pi.  17,  figs  1 and  2. 

Diagnosis.  Pendent  or  declined  rhabdosome  with  regular,  commonly  delayed,  dichotomous 
branching  from  two  primary  stipes.  Sicula  and  most  autothecae  with  bithecae;  autothecae 
composed  of  simple,  dichgraptid-like  tubes,  commonly  curved  with  fairly  high  distal  inclinations, 
stipes  relatively  robust. 

Remarks.  Until  more  extensive  taxonomic  revision  of  Middle  and  Upper  Tremadoc  graptolites  is 
accomplished,  this  genus  is  essentially  monotypic.  A.  victoriae , the  type  species,  has  been  previously 
assigned  to  both  Bryograptus  and  Adelograptus.  It  differs  from  the  former  genus  by  having  two, 
rather  than  three,  primary  stipes,  and  from  the  latter  in  having  a relatively  robust,  large  rhabdosome 
with  regular  branching.  When  preserved  in  radiate,  rather  than  pendent,  orientation,  the 
rhabdosome  gives  an  appearance  which  would  normally  have  been  referred  to  Clonograptus.  As 
discussed  elsewhere,  we  consider  this  genus  to  be  a typically  dichograptid,  Arenig  genus,  lacking 
bithecae  or  any  other  ‘dendroid’  features  (in  the  traditional  sense).  It  is  therefore  likely  that  many 
specimens  referred  previously  to  Clonograptus  are  actually  representatives  of  our  new  genus 
Aorograptus  preserved  in  radiate  (horizontal)  orientation. 

Several  previous  authors  have  referred  to  the  possibility  that  Bryograptus  evolved  to  give  the 
lower  Arenig  dichograptid  genus  Pendeograptus  and/or  the  pendent  didymograptids  (see  Fortey 
and  Cooper  1986  for  discussion).  In  our  opinion,  it  is  likely  that  Aorograptus  evolved  from 
Bryograptus  in  the  late  Tremadoc  through  loss  of  one  primary  stipe  and  the  stolon  system,  then 
subsequently  gave  rise  to  Pendeograptus  through  loss  of  bithecae  and  further  stipe  reduction.  It  is 
not,  however,  the  ancestor  of  Didymograptus  ( Didymograptellus ) Cooper  and  Fortey,  1982,  which 
almost  certainly  evolved  from  the  Didymograptus  ( Expansograptus ) nitidus  group  of  extensiform 
didymograptids  (see  Williams  and  Stevens  1988#). 


text-fig.  10.  Paratemnograptus  isolatus  gen.  et  sp.  nov.,  a-c  x 5,  d-j  x 2-5,  k-o  x 1.  a,  GSC  87301,  MPN17B. 
b,  GSC  87362,  GP38  (also  figured  PI.  2,  fig.  4).  c,  GSC  87370,  GP38.  d,  GSC  87333,  MPS42C.  e,  GSC  87402, 
GP38.  F,  GSC  87280,  CHN8.30.  G,  GSC  8728 1 . CHN8.30.  H,  GSC  87382,  GP38.  i,  GSC  87282,  CHN8.30.  j, 
GSC  87283,  CHN8.30.  k,  GSC  87355,  MPS42C.  l,  GSC  87284,  Holotype,  CHN8.30.  m,  GSC  87334,  MPS42C. 

n,  GSC  87415,  GP40.  o,  GSC  87311,  MPS42C. 


24 


PALAEONTOLOGY,  VOLUME  34 


Aorograptus  victoriae  (T.  S.  Hall,  1899) 

Plate  2,  fig.  1;  Plate  3,  fig.  15?;  Plate  4,  figs  9-14;  Plate  5,  figs  1-8;  Text-fig.  11a-q 

1899 a Bryograptus  victoriae , n.  sp.;  T.  S.  Hall,  p.  165,  pi.  17,  figs  1 and  2. 

1899 a Bryograptus  clarki,  n.  sp.;  T.  S.  Hall,  pp.  165-166,  pi.  17,  figs  3 and  4. 

18996  Bryograptus  victoriae',  T.  S.  Hall,  p.  450,  pi.  22,  figs  11  and  12. 

1914  Bryograptus  sp. ; T.  S.  Hall,  pi.  8,  figs  5 and  6. 

1932  Bryograptus  victoriae  T.  S.  Hall;  Harris  and  Keble,  pi.  4,  fig.  2. 

1933  Bryograptus  pauxillus  sp.  nov. ; Benson,  p.  403  ( nom . mid.). 

1936  Bryograptus  hwmebergensis  Moberg;  Benson  and  Keble  (pars),  pp.  269-270,  pi.  30,  figs  1-11 
(non  pi.  30,  figs  14  and  15  = A.  cf.  tenellus  (Linnarsson)?). 

71936  Bryograptus  simplex  Tornquist;  Benson  and  Keble,  p.  270,  pi.  30,  figs  12  and  13. 

1938 b Bryograptus  victoriae  T.  S.  Hall;  Harris  and  Thomas,  pi.  1,  fig.  7. 

1938  Bryograptus  clarki  T.  S.  Hall;  Harris  and  Thomas,  pi.  1,  fig.  8. 

1941  Adelograptus  victoriae  (T.  S.  Hall);  Bulman,  p.  115  (no  description  or  figures,  but  refers  to 
Adelograptus  and  synonymises  A.  clarki). 

1955  Adelograptus  asiaticus',  Mu,  p.  30,  pi.  10,  figs  4-7. 

71955  Adelograptus  sinicus'.  Mu,  p.  30,  pi.  10,  fig.  8. 

1960  Bryograptus  victoriae  T.  S.  Hall;  Thomas,  pi.  1,  fig.  6. 

1960  Bryograptus  clarki  T.  S.  Hall;  Thomas,  pi.  1,  fig.  7. 

71960  Adelograptus  victoriae  (T.  S.  Hall);  Berry,  pp.  46-47  (remarks  only,  no  descriptions  or  figures). 
1966  Adelograptus  clarki  (T.  S.  Hall);  Berry,  pp.  419-421,  pi.  44,  figs  2 and  4. 

1966  Adelograptus  victoriae  (T.  S.  Hall);  Berry,  pp.  421^422,  pi.  44,  fig.  I. 

1968  Adelograptus  kazakhstanensis  Tzaj,  n.  sp. ; Tzaj,  pp.  493-494,  pi.  5,  fig.  2. 

1968  Bryograptus  ulutanensis  Tzaj,  n.  sp.;  Tzaj,  p.  495,  pi.  5,  fig.  3. 

1969  Bryograptus 7 sp.  of  T.  S.  Hall;  Bulman  and  Cooper,  fig.  Aa,  b. 

1974  Adelograptus  victoriae  (T.  S.  Hall);  Jackson,  p.  45,  pi.  5,  fig.  2;  text-fig.  2a. 

1974  Adelograptus  kazakhstanensis  Tzaj;  Tzaj,  pi.  37,  pi.  1,  figs  6 and  7. 

1974  Bryograptus  ulutanensis  Tzaj;  Tzaj,  pp.  38-39,  pi.  2,  figs  1-3;  fig.  4. 

1974  Bryograptus  sp.;  Tzaj,  p.  39,  pi.  2,  fig.  4. 

1979 a Adelograptus  clarki  (T.  S.  Hall);  Cooper,  pp.  54-55,  pi.  2a,  6;  fig.  19a-c. 

19796  Adelograptus  victoriae  (T.  S.  Hall);  Cooper,  fig.  5 g. 

1979  Adelograptus  victoriae  (T.  S.  Hall);  Cooper  and  Stewart,  pp.  784-785,  text-fig.  8 g,j,  I. 

1979  Adelograptus  asiaticus  Mu;  Wang  et  al.,  pp.  499-500,  pi.  I,  figs  6 and  7;  fig.  8 a-e. 

1979  Adelograptus  simplex  (Tornquist);  Wang  et  al.,  p.  501,  fig.  9a. 

1979  Adelograptus  victoriae  (T.  S.  Hall);  Wang  et  al.,  p.  501,  fig.  96. 

Type  specimen.  Nat.  Mus.  Victoria  No.  PI 4240  (figured  by  Hall  1899,  pi.  44,  fig.  1)  was  designated  lectotype 
by  Berry  (1966,  p.  421).  From  the  middle  Lancefieldian  (La2)  near  Lancefield,  Victoria,  Australia. 


Diagnosis.  Pendent  or  declined  rhabdosome  with  many  stipes  increasing  from  06-08  mm  wide 
proximally  to  a maximum  T2  mm.  Autothecae  with  concave  ventral  margin,  flared  aperture  and 
with  bithecae,  thecal  density  increasing  from  8 in  10  mm  proximally  to  10  in  10  mm  distally. 


EXPLANATION  OF  PLATE  3 

Figs  I and  2.  Kiaerograptus  undulatus  sp.  nov.  GSC  87436,  MPS42C.  1,  x 20,  2,  x 40. 

Figs  3,  4,  7.  Kiaerograptus  magnus  sp.  nov.  3,  GSC  87433,  SPI43.  4,  GSC  87474,  MPS42C.  7,  GSC  87473, 
MPS42C.  All  x 40. 

Figs  5,  6,  8-14.  Kiaerograptus  bulmani  (Thomas,  1963).  5,  GSC  87462,  GP38.  6,  GSC  87434,  SPI43.  8 and  9, 
GSC  87459,  GP38.  10,  GSC  87442,  SPI43.  1 1,  GSC  87443,  SPI43.  12,  GSC  87446,  SPI43  (also  figured  Text- 
fig.  5a,  b).  13,  GSC  87488,  MPS42C.  14,  GSC  87444,  SPI43.  All  x40. 

Fig.  15.  Aorograptus  victoriae  (T.  S.  Hall,  1899)7,  GSC  87465,  MPS42C,  x40. 

Scanning  electron  micrographs  of  isolated  specimens. 


PLATE  3 


WILLIAMS  and  STEVENS,  Kiaerograptus , Aorograptus 


26 


PALAEONTOLOGY,  VOLUME  34 


Material  and  localities.  Many  isolated,  three-dimensional  and  flattened,  non-isolated  specimens  from  all 
localities  in  the  late  Tremadoc  of  the  Cow  Head  Group  described  in  this  paper. 

Description.  The  rhabdosome  has  a pendent  form  with  up  to  sixteen  branches  formed  by  four  delayed 
dichotomies  and  sometimes  exceeds  60  mm  in  diameter.  Occasionally  specimens  are  preserved  flattened  in 
horizontal  orientation;  in  this  instance  the  rhabdosome  has  a radiate,  ‘clonograptid  ’ appearance.  Stipe  widths 
vary  depending  on  astogeny,  but  are  commonly  0-6-0-8  mm  proximally,  increasing  distally  to  a maximum 
T2  mm. 

The  sicula  is  large,  measuring  1 -4-2-0  mm  long;  although  such  variation  is  not  found  in  most  other 
associated  taxa,  detailed  observation  has  revealed  continuous  variation  between  the  extremes  and  taxonomic 
division  based  solely  on  this  criterion  is  therefore  not  warranted.  The  sicula  is  more  or  less  straight,  increasing 
gradually  in  diameter  to  0-25-0-3  mm  at  the  aperture.  The  nema  is  commonly  preserved,  reaching  up  to  4 mm 
long,  and  the  rutellum  is  pronounced,  extending  0-15  mm  beyond  the  antirutellar  margin. 

Thl 1 buds  from  the  prosicula,  growing  down  in  contact  with  the  rutellar  margin  for  0-75  mm  before  bending 
out  at  an  angle  of  70°  to  the  sicular  axis.  It  subsequently  curves  down  throughout  its  length,  ending  subparallel 
to  the  sicular  axis  after  0-8-1 -2  mm.  The  aperture  has  a short  selvage  and  is  0 3-0-4  mm  wide  (one  half  to  two- 
thirds  total  stipe  width).  A sicular  bitheca  buds  from  the  sicula  0-5  mm  below  the  point  of  origin  of  thl1.  It 
varies  tremendously  in  length,  from  little  more  than  a concealed  foramen  to  a theca  with  an  aperture  just  above 
the  point  of  divergence  of  the  ventral  wall  of  thl1.  The  distal  notch  between  the  rutellar  margin  of  the  sicula 
and  thl1  is  also  rather  variable  in  size,  from  0-4-0-6  mm  long. 

Thl  ’ buds  from  thl1  not  far  below  its  point  of  origin,  growing  down  and  across  the  sicula  at  an  angle  of 
20-30°.  Development  may  be  either  dextral  or  sinistral.  The  ventral  wall  of  thl2  intersects  the  antirutellar 
margin  of  the  sicular  aperture,  after  which  the  theca  arches  gently  down  towards  the  thecal  aperture,  the  free 
portion  of  ventral  wall  measuring  0-8-1 -0  mm.  Thl2  is  dicalycal,  giving  rise  to  both  th2*  and  th22. 

T1121  and  th22  are  also  normally  dicalycal,  although  one  dichotomy  is  occasionally  suppressed  to  give  an 
asymmetrical  branching  pattern.  Delayed  but  fairly  regular  dichotomous  branching  occurs  throughout  the 
rhabdosome,  resulting  in  third  or  fourth  order  stipes  in  mature  specimens.  Each  autotheca  possesses  a bitheca, 
whose  apertures  open  on  alternating  sides  of  the  stipe;  these  are  also  clearly  visible  at  each  dichotomy  in 
isolated  material.  Such  a pattern  of  thecae  is  strongly  reminiscent  of  typical  anisograptids,  but  careful 
examination  has  failed  to  reveal  any  hint  of  a stolon  system  embedded  in  the  dorsal  margin. 

Thecal  style  is  consistent  throughout  the  rhabdosome,  autothecae  possessing  concave  ventral  margins  with 
flared  apertures  which  occupy  about  one  half  total  stipe  width.  Interthecal  septae  have  an  initial  inclination  of 
10°  to  the  dorsal  margin,  increasing  ventrally  to  20-30°.  Thecal  overlap  is  approximately  one  half  total  thecal 
length.  Thecal  density  is  unusual  in  that  it  increases  from  8 in  10  mm  proximally  to  10  in  10  mm  distally.  It 
is  unclear  whether  this  is  due  to  more  steeply  inclined  thecae,  shorter  thecae,  or  greater  thecal  overlap,  but  is 
opposite  to  the  situation  found  in  most  graptolites  where  thecal  density  decreases  distally. 

Remarks.  All  previously  described  specimens  of  A.  victoriae , including  the  types,  have  been  small 
rhabdosomes  with  only  second  order  dichotomies.  However,  the  lectotype  has  identical  proximal 
dimensions  and  form  and  we  have  no  hesitation  in  assigning  our  material  to  this  species. 

Bulman  (1941)  was  the  first  to  recognize  that  A.  clarki  was  synonymous  with  A.  victoriae.  Berry 
(1966)  subsequently  considered  the  two  to  be  distinct  taxa,  A.  clarki  being  distinguished  by  lateral 
rather  than  dichotomous  branching  and  less  strongly  declined  stipes.  Cooper  (1979a)  remarked  that 
the  two  would  probably  prove  conspecific;  Cooper  and  Stewart  (1979)  formally  synonymized  them. 


EXPLANATION  OF  PLATE  4 

Figs  1-8.  Paratemnograptus  isolatus  gen.  et  sp.  nov.  1,  GSC  87449,  SPI43.  2,  GSC  87450,  SPI43.  3,  GSC  87439, 
MPS42C.  4,  GSC  87482,  MPS42C.  5,  GSC  87424,  MPS42C.  6,  GSC  87435,  MPS42C.  7,  GSC  87486, 
MPS42C.  8,  GSC  87440,  MPS42C.  All  x 40. 

Figs  9-14.  Aorograptus  victoriae  (T.  S.  Hall,  1899).  9 and  1 1,  GSC  87437,  MPS42C,  x 20.  10,  GSC  87418,  note 
bitheca,  MPS42C,  x 20.  12,  GSC  87422,  MPS42C,  x 20.  13,  GSC  87477,  MPS42C,  x40.  14,  GSC  87425, 
MPS42C,  x 40. 

Scanning  electron  micrographs  of  isolated  specimens. 


PLATE  4 


WILLIAMS  and  STEVENS,  Paratemnograptus , Aorograptus 


28  PALAEONTOLOGY,  VOLUME  34 


text-fig.  1 1 . For  legend  see  opposite. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


29 


We  see  no  justification  in  retaining  two  separate  species  in  the  light  of  our  own  work  and  that  of 
previous  authors,  and  therefore  follow  Bulman  (1941)  and  Cooper  and  Stewart  (1979)  in  regarding 
A.  clarki  as  a junior  synonym  of  A.  victoriae. 

The  species  of  ‘ Bryograptus ’ figured  by  Hall  (1914)  and  Bulman  and  Cooper  (1969)  is  identical 
to  our  mature  specimens  of  A.  victoriae.  Specimens  assigned  to  ‘ B.  pauxillus,  sp.  nov.’  (Benson 
1933)  and  ‘ B.  hunnebergensis  Moberg’  (Benson  and  Keble  1936)  were  recognized  by  Bulman  (1941, 
p.  115)  as  belonging  to  A.  victoriae.  The  proximal  ends  of  ‘ Bryograptus  simplex  Tdrnquist’  figured 
by  Benson  and  Keble  (1936)  appear  similar  in  branching  pattern  and  overall  form  to  A.  victoriae , 
but  the  sicula  is  much  longer  (3  mm  and  4-5  mm  if  their  magnifications  are  correct).  Tornquist’s 
original  specimens  (1904,  pp.  3^1,  pi.  1,  figs  1-4)  have  a similarly  long  sicula,  but  are  recorded  from 
the  T.  phyllograptoid.es  Zone  of  southern  Sweden.  Williams  and  Stevens  (1988a)  considered  this 
interval  to  be  equivalent  to  the  lower  Arenig  T.  akzharensis  Zone  of  the  Cow  Head  Group.  It  is 
therefore  most  likely  that  B.  simplex  is  synonymous  with  Pendeograptus  fruticosus  (J.  Hall)  or  P.  cf. 
P.  pendens  (Elies)  as  described  by  Williams  and  Stevens.  The  similarity  of  A.  victoriae  to  the  lower 
Arenig  P.  fruticosus  is  remarkable:  proximal  development,  rhabdosome  branching  and  thecal  style 
(autothecae  in  A.  victoriae)  are  all  very  similar,  although  the  two  may  be  distinguished  by  the  longer 
sicula  of  P.  fruticosus  and  bithecae  and  more  numerous  branching  in  A.  victoriae. 

The  various  Chinese  and  Russian  species  described  by  Mu  (1955),  Wang  et  al.  (1979)  and  Tzaj 
(1968,  1974)  all  appear  to  be  synonymous  with  A.  victoriae , as  do  the  specimens  figured  by  Wang 
et  al.  (1979,  fig.  9a)  as  A.  simplex  (Tornquist). 

As  noted  in  the  discussion  of  Aorograptus , the  original  assignation  of  A.  victoriae  to  Bryograptus 
is  invalid  following  the  definition  given  by  Bulman  (1970,  p.  V39),  who  stated  that  Bryograptus  is 
an  anisograptid  which  develops  ‘from  three  primary  stipes  by  irregular  and  apparently  lateral 
branching’.  Obut's  (1957)  inclusion  of  both  Bryograptus  and  the  dichograptid  genus  Pendeograptus 
within  a family  Bryograptidae  is  therefore  clearly  unacceptable. 

Genus  adelograptus  Bulman,  1941 

Type  species  (by  original  designation).  Bryograptus ? Hunnebergensis  Moberg,  1892,  p.  92,  pi.  2,  figs  5-7  (?8  and 
9). 

Diagnosis,  (revised  using  Bulman  1941,  p.  114).  Rhabdosome  declined  or  horizontal,  often 
somewhat  lax  and  flexuous,  formed  from  two  primary  branches  by  regular  or  irregular,  commonly 
delayed,  dichotomous  branching.  Sicular  bitheca  always  present,  additional  bithecae  and  stolothecae 
present  in  some  species,  absent  in  others,  autothecae  straight,  with  simple  apertures  and  low 
inclination,  stipes  consequently  slender. 

Remarks.  The  revision  of  Adelograptus  permits  incorporation  of  many  slender,  regularly  branching 
taxa  previously  accommodated  within  the  rather  unsatisfactory  genus  Clonograptus.  The  type 
species  of  Clonograptus  (C.  rigidus ) is  now  recognized  as  having  a Lower  Arenig  age  and  probably 
belongs  within  the  dichograptids  (see  previous  discussion  in  text).  Other  more  robust,  pendent 
species  originally  assigned  to  Bryograptus  (e.g.  ' B.  ’ victoriae)  but  since  transferred  to  Adelograptus 
(Bulman  1941)  because  of  their  two  primary  stipes  are  here  assigned  to  a new  genus  Aorograptus 
(see  generic  remarks). 

Although  such  a classification  still  has  its  limitations,  it  is  closer  to  a true  phylogenetic  grouping 


text-fig.  11.  Aorograptus  victoriae  (T.  S.  Hall,  1899),  a-g  x 5,  h-q  x 2 5.  a,  GSC  87374,  GP38,  b,  GSC  87401, 
GP38.  c,  GSC  87405,  GP38.  d,  GSC  87297,  CHN8.32.  e,  GSC  87295,  CHN8.34.  f,  GSC  87367,  GP38.  G,  GSC 
87397,  GP38.  h,  GSC  87326,  MPS42C.  i,  GSC  87379,  GP38.  J,  GSC  87332,  MPS42C.  k,  GSC  87310,  MPS42C. 
l,  GSC  87309,  MPS42C  (also  figured  PI.  2,  fig.  1).  m,  GSC  87355,  MPS42C.  n,  GSC  87321,  MPS42C.  o,  GSC 
87320,  MPS42C.  p,  GSC  87336,  MPS42C.  Q,  GSC  87313,  MPS42C. 


30 


PALAEONTOLOGY,  VOLUME  34 


than  that  used  previously,  all  members  having  similar  proximal  developments  and  thecal  styles.  It 
permits  the  transfer  of  Clonograptus  tenellus  Linnarsson  to  Adelograptus  as  suggested  by  Maletz  and 
Erdtmann  (1987),  making  sense  of  Hutt’s  (1974)  observation  that  C.  tenellus  and  A.  hunnebergensis 
have  identical  proximal  development  patterns  and  may  only  be  distinguished  following  subsequent 
branching. 

In  his  original  diagnosis,  Bulman  (1941)  stated  that  branching  in  Adelograptus  was  apparently 
lateral  rather  than  dichotomous.  All  studies  using  isolated  material  of  the  genus  since  that  time, 
including  the  present  study  and  that  of  Hutt  (1974),  have  found  branching  to  be  dichotomous;  the 
diagnosis  is  therefore  consequently  emended. 

The  genus  Par  adelograptus  was  erected  recently  by  Erdtmann  et  al.  (1987)  for  non-bithecate 
forms  which  would  previously  have  been  assigned  to  Adelograptus  or  Clonograptus.  The  genus  is 
characterized  by  slender  thecae  with  simple  or  modified  apertures,  and  considered  to  be  ancestral 
to  Kinnegraptus  Skoglund,  1961  and  other  kinnegraptid  genera.  All  their  described  species  are  from 
the  lower  Arenig  and  lack  a sicular  bi  theca ; none  of  our  taxa  may  therefore  be  accommodated  within 
this  genus. 


Adelograptus  altus  sp.  nov. 

Plate  5,  figs  9-13;  Plate  5,  figs  14?  and  15?;  Text-fig.  12a-g 

1979  Adelograptus  sp. ; Cooper  and  Stewart,  text-fig.  Id-f,  h (no  description). 

Derivation  of  name.  From  altus  (Latin)  meaning  ‘high’,  in  reference  to  the  relatively  high  level  of  divergence 
of  the  first  two  thecae  from  the  sicula. 

Type  specimen.  The  holotype  is  GSC  87430,  an  isolated  specimen  mounted  on  an  SEM  stub,  from  MPS42C. 
Figured  Plate  5,  figure  12. 

Diagnosis.  Sicula  T5-F8  mm  long  with  distal  convex  curvature,  with  both  rutellar  and  antirutellar 
margins  free  distally.  Sicular  bitheca  opens  at  same  level  where  ventral  wall  of  th  1 1 diverges  from 
sicula.  Thl1  and  l2  are  gently  declined  with  concave  free  ventral  margins  and  gently  flared  apertures, 
increasing  from  0-2  mm  diameter  to  0-4— 0-5  mm  at  the  aperture. 

Material  and  localities.  Nine  isolated,  three-dimensional  proximal  fragments,  eight  flattened,  non-isolated 
proximal  fragments.  Several  possible  mature,  non-isolated  rhabdosomes.  From  CHN8.30,  SPI43,  MPN17B. 
MPS42C. 

Description.  The  species  is  defined  primarily  on  its  distinctive  pattern  of  proximal  development.  Overall  form 
is  apparently  similar  to  that  of  A.  cf.  tenellus  (Moberg)  with  the  exception  of  a slightly  narrower  funicle,  but 
the  two  are  clearly  separated  by  the  proximal  form  seen  both  in  flattened  and  isolated  material. 

The  sicula  is  F5-F8  mm  long  measured  along  the  rutellar  margin,  with  a distal  convex  curvature.  The  sicular 
aperture  is  0-2-0-25  mm  wide,  with  a pronounced  rutellum  extending  0 05—0- 1 mm  beyond  the  antirutellar 
margin.  Thl1  buds  from  the  prosicula  on  the  rutellar  side,  growing  down  along  this  margin  for  0-6-0-75  mm 


EXPLANATION  OF  PLATE  5 

Figs  1-8.  Aorograptus  victoriae  (T.  S.  Hall,  1899).  1,  GSC  87421,  MPS42C,  x 40.  2,  GSC  87457,  MPS42C, 
x 40.  3,  GSC  87426,  MPS42C,  x 40.  4,  GSC  87475,  x40.  5,  GSC  87472,  MPS42C,  x20.  6,  GSC  87453, 
MPS42C,  x 40.  7,  GSC  87478,  MPS42C,  x20.  8,  GSC  87487,  MPS42C,  x 20. 

Figs  9-  13.  Adelograptus  altus  sp.nov.  MPS42C,  x 40  except  Fig.  1 1 (=  x 20).  9,  GSC  87429.  10  and  1 1,  GSC 
87441.  12,  GSC  87430,  Holotype.  13,  GSC  87455. 

Figs  14  and  15.  Adelograptus  altus  sp.  nov.?  Juvenile  growth  stages,  x40.  14,  GSC  87460,  GP38.  15,  GSC 
87427,  MPS42C. 

Scanning  electron  micrographs  of  isolated  specimens. 


PLATE  5 


WILLIAMS  and  STEVENS,  Aorogrciptus , Adelograptus 


32 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  12.  a-g,  Adelograptus  altus  sp.  nov.,  a-e  x 5,  F and  G,  x 2-5.  a,  GSC  87302,  MPN17B.  b,  GSC  87377, 
GP38.  c,  GSC  87360,  MPS42C.  d,  GSC  87337,  MPS42C.  e,  GSC  87341.  MPS42C.  f,  GSC  87285,  CHN8.30. 
G,  GSC  87300,  SPI43.  h and  i,  Adelograptus  antiquus  (T.  S.  Hall,  1899)7,  x 5.  h,  GSC  87340,  MPS42C.  i,  GSC 

87416,  GP40. 


before  turning  sharply  out,  subtending  an  angle  of  70-80°  with  the  distal  sicular  axis.  The  rutellar  wall  of  the 
sicula  is  free  for  0-4-0-6  mm  distally,  while  the  sicular  bitheca  opens  cryptically  at  the  same  level  at  which  the 
ventral  wall  of  th  1 1 diverges  from  the  sicula.  The  point  of  origin  of  the  bitheca  is  unclear  and  appears  to  be 
concealed  by  the  early  dorsal  wall  of  th  1 1 . The  stipe  is  01 5-0-2  mm  wide  where  th  1 1 leaves  the  sicula;  the  free 
ventral  wall  of  th  1 1 has  as  strong  concave  curvature,  leading  to  a splayed-out  aperture  and  an  undeformed 
apertural  stipe  width  of  0-4-0-5  mm.  The  ventral  wall  of  th  1 1 is  free  for  L0-L2mm  before  the  aperture  is 
reached,  which  is  0-25-0-3  mm  wide  (i.e.  two-thirds  of  total  stipe  width). 

Thl2  buds  from  th  1 1 0-5  mm  below  its  origin,  growing  immediately  across  and  down  the  sicula  at  45-50° 
from  the  sicular  axis.  Development  may  be  either  right-  or  left-handed;  it  is  therefore  meaningless  to  discuss 
reverse  and  obverse  aspects  of  the  sicula,  as  these  vary  from  one  specimen  to  the  next.  Once  thl2  has  reached 
the  antirutellar  margin  of  the  sicula  it  turns  up  slightly,  subtending  an  angle  of  3(U40°  with  the  distal  sicular 
axis  in  most  cases.  It  has  a similar  concave  ventral  margin  and  splayed-out  aperture  to  thl1,  the  stipe  width 
measuring  0-2  mm  initially,  but  increasing  to  0-4-0-5  mm  (undeformed)  by  the  aperture. 

The  budding  of  th21  and  22  appears  to  be  typically  isograptid,  with  thl2  dicalycal.  There  is  no  evidence  for 
further  dichotomies  in  isolated  material,  but  one  non-isolated  specimen  assigned  to  this  species  (Text-fig.  12e) 
and  those  of  Cooper  and  Stewart  (1979)  show  dichotomous  branching  of  th2x  and  22.  Measurement  of  several 
slender  ‘clonograptid  ’ rhabdosomes  demonstrates  several  with  funicles  of  equivalent  width  to  that  which 
would  be  expected  from  isolated  specimens.  We  conclude  that  although  branching  is  variable,  mature 
rhabdosomes  have  overall  appearances  of  those  specimens  illustrated  in  Text-figure  12f,  g. 

Remarks.  The  description  of  A.  altus  is  based  primarily  on  isolated,  three-dimensional  material, 
making  comparison  with  other  similar  Adelograptus  species  difficult  if  known  only  from  flattened, 
non-isolated  specimens.  The  proximal  budding  pattern  is  similar  to  those  shown  by  A.  cf.  A . tenellus 
and  Adelograptus  sp.  A,  but  the  sicula  is  longer  than  that  of  A.  cf.  A.  tenellus  and  shorter  than  that 
of  Adelograptus  sp.  A,  while  most  specimens  have  a prominent  ‘notch'  between  the  free  ventral  wall 
of  thl2  and  the  distal  antirutellar  margin  of  the  sicula.  Comparison  using  overlays  clearly  shows  the 
incompatibility  of  the  three  species  in  terms  of  exact  budding  patterns  and  angles  of  thecal 
inclination. 

The  specimens  figured  by  Cooper  and  Stewart  (1979)  as  Adelograptus  sp.  are  identical  to  those 
described  here,  with  the  exception  of  thl1  which  is  marginally  shorter.  Unfortunately  they  did  not 
describe  their  material  or  make  any  reference  to  it  in  the  text.  No  other  comparable  specimens  have 
been  described  or  figured  previously. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GR APTOLITES 


33 


text-fig.  13.  Adelograptus  cf.  A.  tenellus  (Linnarsson,  1871),  a-f  x 5,  g x 10,  h-j  x 2 5.  A,  GSC  87403,  GP38. 
b,  GSC  87389,  GP38.  c,  GSC  87409,  GP38.  d,  GSC  87303,  MPN17B.  E,  GSC  87347,  MPS42C.  f,  GSC  87348, 
MPS42C  G,  GSC  87349,  MPS42C.  h,  GSC  87398,  GP38.  i,  GSC  87394,  GP38.  J,  GSC  87395,  GP38. 


Adelograptus  cf.  A.  tenellus  (Linnarsson,  1871) 

Plate  2,  figs  2 and  3;  Text-fig.  1 3a— j 
cf.  1871  Dichograptus  tenellus ; Linnarsson,  p.  795,  pi.  16,  figs  13-15. 

cf.  1909  Clonograptus  tenellus  Linnarsson  (and  vars.);  Westergard,  pp.  68-72,  pi.  4,  figs  17-29. 
cf.  1929  Clonograptus  tenellus  (Linnarsson);  Stubblefield,  pp.  278-262,  text-figs  1,  8-11. 

1936  Bryograptus  hunnebergensis  Moberg;  Benson  and  Keble  (pars),  pp.  269-270,  pi.  30,  figs  14  and 
15  (non  pi.  30,  figs  1-11  = A.  victoriae  (T.  S.  Hall)), 
cf.  1987  Adelograptus  tenellus  (Linnarsson);  Maletz  and  Erdtmann,  pp.  180-182,  pi.  1,  figs  a-c,  pi.  2,  figs 
a-m. 

Material  and  localities.  About  ten  flattened  specimens  from  MPN17B,  MPS42C  and  GP38  and  five  isolated, 
three-dimensional  specimens  from  MPS42C. 

Description.  Rhabdosome  with  several  slender  stipes  formed  by  delayed  dichotomous  branching  from  two 
primary  stipes.  The  largest  rhabdosome  seen  has  a diameter  of  about  30  mm,  with  four  dichotomies  on  the 
most  complete  portion,  suggesting  a total  of  thirty-two  stipes.  Dichotomous  branching  is  apparently  irregular, 
with  a normal  spacing  of  3-5  mm  (i.e.  every  two  or  three  thecae).  Thecal  outline  is  rarely  seen  owing  to 


34 


PALAEONTOLOGY,  VOLUME  34 


preservation  in  scalariform  view,  but  when  present  stipe  width  is  seen  to  measure  0-35-0-4  mm  proximally, 
increasing  distally  to  a maximum  0-6  mm. 

The  sicula  is  1-1-1 -4  mm  long,  and  has  a gentle  convex  curvature  with  respect  to  the  rutellar  margin  in  the 
distal  one-third  to  one  halt'  its  length.  It  is  0-2-0-25  mm  wide  at  the  aperture,  with  a slight  rutellum.  Thl1  buds 
from  the  prosicula  on  the  rutellar  margin.  It  grows  down  in  contact  with  this  margin  for  0-6-0-7  mm,  before 
deflecting  sharply  out,  subtending  an  angle  of  about  100°  with  the  sicular  axis.  This  leaves  the  distal  rutellar 
margin  of  the  sicula  free  for  0-4-0-5  mm.  Thl1  then  curves  gently  downwards  until  its  aperture  is  reached, 
leaving  a free  ventral  wall  1 -0—1  - 1 mm  long.  The  thecal  aperture  is  0-3  mm  wide  with  a prominent  flaring  at  the 
tip  in  some  specimens.  A sicular  bitheca  is  present,  originating  a little  below  the  point  of  origin  of  thl1  on  the 
obverse  side.  The  level  of  its  aperture  lies  a little  above  the  point  of  deflection  of  thl1,  and  is  therefore  not  seen 
except  in  isolated  specimens. 

Thl2  buds  high  up  from  thl1,  growing  down  and  across  the  sicula  on  the  reverse  side,  then  curving  out  so 
that  its  ventral  wall  cuts  the  base  of  the  antirutellar  sicular  margin.  It  subtends  an  angle  of  60-70°  with  the 
sicular  axis  at  its  point  of  divergence;  this  angle  is  maintained  for  the  remaining  TO- 1-1  mm  of  growth, 
although  the  theca  sometimes  curves  down  very  slightly  before  the  aperture.  The  funicle  formed  by  the  sicula 
and  first  two  thecae  measure  2-5— 2-8  mm  long  when  preserved  horizontally  to  bedding. 

Th2‘a  buds  from  thl2  on  the  rutellar  margin  of  the  reverse  side  some  0-7  mm  above  the  base  of  the  rutellum. 
It  follows  the  dorsal  wall  of  thl1  until  just  before  the  aperture  is  reached;  at  this  point  th21b  buds  from  th21a, 
the  two  growing  in  contact  for  about  0-15  mm  before  the  aperture  of  thl1  is  reached.  They  then  diverge  to  give 
the  first  dichotomous  branch.  Although  bithecae  are  apparently  lacking  on  most  thecae,  branching  fragments 
belonging  to  this  or  a related  species  show  a bithecal  aperture  above  the  aperture  of  the  autotheca  when 
dichotomous  branching  occurs.  Bithecae  also  occur  at  the  dichotomies  of  several  other  unrelated  late 
Tremadoc  taxa,  and  are  thought  to  represent  an  intermediate  stage  towards  total  loss  of  bithecae. 

Th22a  buds  from  thl2  near  its  point  of  divergence  from  the  sicula,  developing  and  branching  in  a similar 
fashion  to  th21a.  Each  stipe  then  divides  dichotomously  every  two  to  three  thecae.  Thecal  density  is  a low,  6-7 
in  10  mm  where  visible,  although  this  is  difficult  to  determine  owing  to  frequent  branching  and  usual 
preservation  in  scalariform  view. 

Remarks.  Adelograptus  tenellus  was  revised  recently  by  Maletz  and  Erdtmann  (1987),  who  selected 
a neotype  and  thoroughly  discussed  the  morphological  variation  found  within  the  species.  They 
conclude  the  nominate  species  to  be  a lower  Tremadoc  form  occurring  definitely  only  in 
Scandinavia,  the  Baltic  region  and  Britain.  Records  of  the  species  from  late  Tremadoc  strata  are, 
therefore,  likely  to  be  erroneous.  Our  material  differs  from  the  type  material  in  having  a shorter 
funicle  and  noticeably  lower  thecal  density.  Variation  is  so  great  that  definition  of  a new  taxon  is 
withheld  pending  further,  more  detailed  quantitative  studies  of  late  Tremadoc  material  both  from 
western  Newfoundland  and  elsewhere. 

A few  previously  published  descriptions  include  material  comparable  to  ours;  some  of 
Westergard’s  (1909)  specimens  of  C.  tenellus  and  varieties  are  very  similar,  but  there  is  a great  deal 
of  variation  in  his  figured  specimens  and  probably  more  than  one  species  represented.  C.  tenellus 
kingi  Benson  and  Keble,  1936  is  similar  in  overall  form,  but  thecal  density  is  extremely  high  (17-21 
in  10  mm).  Their  specimen  of 'C.  tenellus'  (1936,  pi.  32,  fig.  4)  also  has  a high  thecal  count.  Benson 
and  Keble  (1936,  pi.  30,  figs  14  and  15)  figured  two  proximal  fragments  more-or-less  identical  to  our 
material;  these  are  referred  to  Bryograptus  simplex  Tornquist  in  the  plate  description,  as  are  figs  12 
and  1 3.  The  latter  two  specimens  have  a very  different  appearance,  are  referred  to  ‘ B.  hunnebergensis ' 
in  the  text,  and  probably  belong  to  A.  victoriae  (see  discussion  of  A.  victoriae  elsewhere  in  this 
paper). 

The  Newfoundland  specimens  of  A.  cf.  tenellus  have  a wider  funicle  than  ‘C.  tenellus  sensu  lato' 
of  Cooper  (19796,  fig.  5c)  and  Cooper  and  Stewart  (1979,  fig.  8m);  both  these  appear  to  be  a 
different  species. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


35 


Adelograptus  antiquus  (T.  S.  Hall,  1899)? 

Text-fig.  12h,  i 

? 1 899  Leptograptus  antiquus , n.  sp.;  T.  S.  Hall,  p.  166,  pi.  17,  figs  5 and  6. 

? 1979a  Adelograptus!  antiquus  (T.  S.  Hall);  Cooper,  pp.  51-54,  pi.  2,  fig.  c-e\  fig.  \la-k.  18. 

71979  Kiaerograptus  antiquus  (T.  S.  Hall);  Cooper  and  Stewart,  pp.  791-792,  text-fig.  8 d,  e.  (summary 
only) 

Material  and  localities.  Two  flattened  specimens  from  MPS42C  and  GP40. 

Remarks.  Careful  comparison  of  these  two  specimens  with  Adelograptus  species  from  western 
Newfoundland  reveals  them  to  differ  in  terms  of  their  small,  slender  sicula,  wide  funicle  and  low 
thecal  density.  These  however  appear  to  agree  with  those  given  for  A.  antiquus  by  Cooper  (1979<r/) 
in  his  detailed  revision  of  the  species,  but  are  insufficient  for  certain  identification.  Their  slender, 
widely  spaced  proximal  region  is  reminiscent  more  of  Adelograptus  than  Kiaerograptus , which  is 
why  we  return  the  species  to  the  former  genus  as  assigned  questionably  by  Cooper  (1979u). 


Adelograptus  sp.  A 
Plate  6,  figs  1-5;  Text-fig.  14h,  j 

Material  and  localities.  Three  flattened,  non-isolated  specimens  from  MPN17B,  MPS42C  and  GP40.  Nine 
three-dimensional,  isolated  specimens  from  MPS42C. 

Description.  This  species  is  known  only  from  isolated  and  non-isolated  proximal  fragments;  overall  form  of  the 
rhabdosome  is  consequently  uncertain. 

The  most  distinctive  feature  is  the  long,  thin  sicula,  which  is  commonly  1 -5  mm  long.  It  is  straight  throughout 
the  first  two-thirds  of  its  length,  but  displays  a gentle,  distal  convex  curvature  with  respect  to  the  rutellar 
margin.  The  rutellum  is  pronounced,  extending  015-0-2  mm  beyond  the  antirutellar  margin. 

Thl1  buds  from  the  prosicula,  growing  down  along  the  rutellar  margin  for  0-6-0-8  mm  before  bending  out 
sharply,  subtending  an  angle  of  60-70°  with  the  sicular  axis  and  leaving  the  rutellar  margin  free  for  05- 

0 6 mm.  A prominent  sicular  bitheca  buds  from  the  sicula  about  half  way  down  the  metasicula  on  the  reverse 
side.  It  has  a prominent  aperture  lying  between  the  rutellar  margin  of  the  sicula  and  ventral  wall  of  thl1,  a little 
below  the  point  where  the  ventral  wall  of  th  1 1 leaves  the  sicular  margin.  Thl 1 is  0-2  mm  wide  at  the  point  where 
it  diverges  from  the  sicula.  Its  free  ventral  wall  is  0-9-11  mm  long  and  almost  straight,  but  flares  towards  the 
aperture  which  measures  0-4  mm  wide  (one  half  total  stipe  width). 

Thl2  buds  from  thl1  on  the  obverse  side  just  above  its  point  of  deflection.  It  grows  down  and  across  the 
sicula,  the  ventral  wall  diverging  from  the  antirutellar  margin  a little  above  the  sicular  aperture.  This 
occasionally  results  in  a slight  ‘notch’  at  the  base  of  the  antirutellar  wall.  Thl2  grows  down  at  40-50°  from  the 
distal  sicular  axis;  it  is  almost  straight  but  flares  slightly  towards  the  aperture.  The  free  ventral  wall  is  07- 
0-8  mm  (i.e.  less  than  that  of  thl1),  while  thecal  widths  are  similar. 

Development  of  th2 1 and  th22  is  as  found  for  other  associated  taxa;  one  or  both  are  sometimes  dichotomous, 
or  dichotomies  may  be  delayed  by  one  or  more  thecae.  As  stated  above,  overall  form  of  the  rhabdosome  is 
uncertain. 

Remarks.  This  species  may  be  distinguished  from  other  coexisting  taxa  by  its  long,  slender  sicula  and 
levels  of  divergence  of  thl1  and  thl2  from  the  sicula.  Dichotomous  branching  is  irregular  and  may 
be  delayed  or  consecutive.  As  the  overall  form  of  the  rhabdosome  is  uncertain  and  only  limited 
material  is  available,  it  would  be  unwise  to  formally  erect  a new  species  at  the  present  time. 

No  previously  described  taxa  of  similar  type  have  a sicula  approaching  this  size.  From  the  few 
larger  fragments  found,  overall  style  of  branching  appears  to  be  most  similar  to  the  irregular  form 

01  Adelograptus  antiquus  (T.  S.  Hall). 


36 


PALAEONTOLOGY,  VOLUME  34 


Adelograptus  filifonnis  sp.  nov. 

Text-fig.  14a-g 

? 1936  Bryograptus  (?)  antiquus  var.  inusitatus  var.  nov.;  Benson  and  Keble,  pp.  267-268,  pi.  30,  figs 
17  and  18. 

1974  Kiaer ogr aptus( ? ) cf.  pritchardi  (T.  S.  Hall);  Jackson,  p.  51,  pi.  5,  fig.  3;  text-fig.  2a,  c , d. 

71982  Kiaerograptus  antiquus  (T.  S.  Hall);  Gutierrez  Marco,  fig.  2 a-e. 

Derivation  of  name.  From  filum  (Latin),  meaning  thread-like,  in  reference  to  the  extremely  slender  stipes. 
Type  specimen.  The  holotype  is  GSC  87391,  figured  Text-figure  14a.  From  GP38. 


Diagnosis.  Extremely  slender,  biramous,  declined  to  pendent  rhabdosome,  stipes  measuring 


text-fig.  14.  a-g,  Adelograptus  filifonnis  sp.  nov.  a,  GSC  87391,  Holotype,  GP38,  x 5.  b,  GSC  87387,  GP38, 
x 10.  c,  GSC  87350,  MPS42C,  x 10,  d.  GSC  87298,  CHN8.32,  x 10.  e,  GSC  87299,  SPI43,  x 5.  F,  GSC  87304, 
MPN17B,  x 5.  G,  GSC  87305,  MPN17B,  x 10.  h-j,  Adelograptus  sp.  A,  x 5.  h,  GSC  87417,  GP40.  i,  GSC 

87306,  MPN17B  j,  GSC  87312,  MPS42C 


EXPLANATION  of  plate  6 

Figs  1-5.  Adelograptus  sp.  A.  MPS42C,  x 40.  1 . GSC  87469.  2,  GSC  8743 1 . 3,  GSC  87484.  4 and  5,  GSC  87468. 
Figs  6-10.  Stipe  fragments  and  branches  from  indet.  Adelograptus.  MPS42C.  6 and  7,  GSC  87438,  x 20.  8, 
GSC  87432,  x40.  9,  GSC  87466,  x20.  10,  GSC  87485,  x40. 

Figs  1 1-15.  Indet.  juvenile  growth  stages.  1 1,  GSC  87445,  SP143,  x 40.  12,  GSC  87489,  SPI43,  x40.  13,  GSC 
87447,  SPI43,  x40.  14,  GSC  87463,  GP38,  x 80.  15,  GSC  87461,  GP38,  x 80. 

Figs  16-18.  Clonograptus  sp.  B.  16,  GSC  87458,  MPS42C,  x40.  17,  GSC  87428,  MPS42C,  x 20.  18,  GSC 
87467,  MPS42C,  x 20. 

Scanning  electron  micrographs  of  isolated  specimens. 


PLATE  6 


WILLIAMS  and  STEVENS,  Adelograptus , Clonogruptus 


38 


PALAEONTOLOGY,  VOLUME  34 


0-2-0- 3 mm  at  thecal  apertures,  but  only  0 08-0-1  mm  directly  after  apertures.  Sicula  with  bitheca, 
other  bithecae  apparently  lacking.  Thl1  with  high  divergence,  leaving  0- 5-0-6  mm  of  distal  sicula 
wall  free.  Thecal  density  6-6-5  in  10  mm. 

Material  and  localities.  Two  probable  isolated  fragments  from  MPS42C.  Eleven  non-isolated,  flattened 
specimens  from  CHN8.32;  SPI43;  MPN17B,  MPS42C;  GP38. 

Description.  The  rhabdosome  consists  of  two  extremely  slender,  gently  declined  stipes.  The  longest  stipes 
fragment  present  in  the  material  from  western  Newfoundland  is  only  10  mm  long;  one  of  the  specimens  figured 
by  Jackson  (1974,  text-fig.  Id)  however  had  stipe  about  18  mm  long  with  strong  convex  curvature,  such  that 
distally  the  stipes  pointed  inwards.  Stipe  width  at  the  initial  free  part  of  each  theca  is  a uniform  0-08-0T  mm, 
increasing  to  0-2-0-3  at  the  aperture. 

The  sicula  is  1 -2-1  -4  mm  long,  with  an  apertural  width  of  0-2-0-25  mm.  It  is  inclined  with  respect  to  the  stipes, 
has  a strong  convex  curvature  with  respect  to  the  rutellar  margin  and  a pronounced  rutellum.  Proximal 
development  is  unclear;  thl1  buds  from  the  prosicula  and  grows  down  in  contact  with  the  rutellar  wall  of  the 
sicula  for  only  about  0-5  mm  before  diverging  sharply  out,  subtending  an  angle  of  60-70°  with  the  sicular  axis. 
The  distal  rutellar  margin  of  the  sicula  is  left  free  for  0-5-0-6  mm  (rarely  0-4  mm).  The  dorsal  thecal  margin 
remains  straight,  but  the  ventral  wall  curves  gently  down  towards  the  aperture,  such  that  inclination  of  the 
ventral  wall  with  the  dorsal  stipe  margin  increases  from  about  0°  proximally  to  30°  at  the  level  of  the  aperture. 
The  free  portion  of  thl 1 is  of  variable  length,  measuring  1-2-1  -5  mm  (cf.  Jackson  1974,  whose  specimens  had 
an  extremely  short  free  portion  of  0-5-0-8  mm).  The  aperture  of  thl1  and  remaining  thecae  occupies  two  thirds 
of  total  stipe  width.  Although  no  hint  of  a sicular  bitheca  has  been  seen  in  any  flattened,  non-isolated 
specimens,  the  isolated  material  clearly  shows  a small  bithecal  aperture  in  the  notch  left  by  the  divergence  of 
thl1  from  the  rutellar  wall  of  the  sicula. 

Thl2  apparently  buds  from  thl1  at  its  point  of  deflection.  Initially  it  grows  across  and  slightly  down,  then 
runs  in  contact  with  the  antirutellar  margin  of  the  sicula  until  the  sicular  aperture  is  reached.  It  subsequently 
turns  out  at  an  angle  of  20-30°  from  the  distal  sicular  axis.  The  free  ventral  wall  of  thl1  part  of  thl2  and  that 
of  all  subsequent  thecae  behave  as  thl 1 . The  origin  of  th2‘  is  unclear;  if  development  is  similar  to  other  species 
from  this  assemblage,  it  would  bud  from  thl2.  In  this  instance,  it  must  have  an  extremely  slender  protheca  less 
than  0-05  mm  wide.  With  the  exception  of  the  sicular  bitheca,  there  appears  to  be  no  other  bithecae  in  the 
rhabdosome,  neither  does  there  appear  to  be  any  branching.  Thecal  density  is  exceptionally  low  throughout 
the  rhabdosome,  at  a constant  6-6-5  in  10  mm. 


Remarks.  The  only  previous  certain  record  of  this  distinctive  but  elusive  species  was  by  Jackson 
(1974),  who  referred  it  to  AT?  cf.  pritchardi.  His  specimens  from  the  Yukon,  northern  Canada  are 
very  similar  but  differ  in  the  shorter  free  portion  of  thl2  (0- 5-0-8  mm  as  opposed  to  1 -2-1-5  mm). 
The  free  portion  of  thl2  is,  however,  comparable  in  length  to  that  of  our  specimens  (1-3-1  -7  mm  as 
opposed  to  1-2-1-4  mm),  as  is  thecal  density  and  stipe  width.  Judging  from  his  illustrated  examples, 
it  appears  that  such  variation  may  have  been  due  to  tectonic  stretching  (note  particularly  his  text- 
fig.  2d). 

Although  several  other  slender  taxa  found  within  this  stratigraphical  interval  are  similar  in 
appearance,  K.  filiformis  may  be  reliably  distinguished  from  them  all  by  its  high  divergence  of  thl 1 
from  the  sicula,  extremely  narrow  stipes  in  the  portion  immediately  following  the  apertures,  and  low 
thecal  density.  As  recorded  by  Jackson  (1974),  no  specimen  seems  to  have  possessed  more  than  two 
stipes. 

Cooper  (1979a)  expanded  the  definition  of  Adelograptus  antiquus  (T.  S.  Hall)  to  include  a variety 
of  forms  with  siculae  and  first  two  thecae  of  varying  dimensions  and  emphasizing  the  symmetry  of 
the  proximal  end.  We  accept  this  revision,  but  our  specimens  fall  well  outside  his  described 
population  with  a consistently  longer  and  more  slender  sicula  and  longer  first  two  thecae.  Thecal 
spacing  is  also  lower  at  6-6-5  in  10  mm  instead  of  7 in  10  mm.  Some  of  Cooper’s  end  members  (e.g. 
Cooper  1979a,  fig.  17//)  approach  A.  filiformis,  but  are  still  noticeably  different.  Cooper  (1979a) 
included  A.?  cf.  pritchardi  of  Jackson  (1974)  and  B.2  antiquus  inusitatus  Benson  and  Keble,  1936 
with  A.  antiquus.  Although  they  appear  to  be  tectonically  deformed,  in  our  opinion  Jackson’s 
specimens  seem  closer  to  A.  filiformis  than  to  A.  antiquus , with  the  exception  ot  a short  thl1. 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GR APTOLITES 


39 


Although  Jackson  (1974)  recorded  thecal  density  as  9-10  in  10  mm,  this  varies  from  7-10  in  10  mm 
in  his  figured  specimens,  depending  on  orientation  to  stretching  direction.  Cooper  (1979a,  p.  53) 
pointed  out  that  Benson  and  Keble’s  figured  specimen  of  B.  ? antiquus  inusitatus  differed  from  their 
written  description,  notably  by  having  wider  thecal  spacing  (3-3-5  instead  of  6-7  in  10  mm).  This 
would  seem  to  be  caused  by  an  error  in  scale  of  illustration  (probably  x 4 rather  than  x 2),  but  as 
their  types  have  not  been  located  (Cooper,  1979a,  p.  33),  this  is  impossible  to  ratify,  neither  is  the 
affinity  of  B.  ? antiquus  inusitatus  with  either  A.  antiquus  or  A.  filiformis. 

Genus  clonograptus  Nicholson,  1873 

Type  species.  Graptolithus  rigidus  J.  Hall,  1858,  p.  146.  Subsequently  designated  by  Miller  (1889,  p.  179). 

Remarks.  Clonograptus  has  been  considered  a typically  ‘dendroid'  genus  (in  the  traditional  sense: 
cf.  Fortey  and  Cooper  1986)  by  most  authors  since  its  original  designation,  although  the 
dichograptid  appearance  of  its  autothecae  and  apparent  lack  of  bithecae  or  stolon  system  has  been 
noted  by  several  workers  (e.g.  Jackson  1973;  Braithwaite  1976).  Recognizing  this,  Maletz  and 
Erdtmann  (1987,  p.  180)  included  Clonograptus  within  the  Dichograptidae  rather  than  the 
Anisograptidae,  and  transferred  many  taxa  previously  included  within  the  genus  to  Adelograptus. 

We  consider  the  type  species  of  Clonograptus  to  be  synonymous  with  one  of  Hall’s  other  species, 
‘ Graptolithus  ’ (usually  referred  to  Clonograptus)  flexilis , first  described  in  the  same  publication  as 
C.  rigidus  on  the  preceding  page  (J.  Hall  1858,  pp.  145-146).  It  could  be  argued  that  C.  rigidus  is 
therefore  a junior  synonym  of  C.  flexilis , but  we  consider  it  best  to  retain  C.  rigidus  as  the  species 
name  in  the  cause  of  nomenclatorial  stability. 

Restudy  of  Hall’s  type  material  from  Levis,  Quebec  by  one  of  us  (S.H.W.),  revealed  the  types  of 
both  species  to  originate  from  the  lower  Arenig  of  that  locality,  an  interval  equivalent  to  the  T. 
akzharensis  Zone  of  western  Newfoundland  (Williams  and  Stevens  1988).  This  zone  separates  the 
T.  approximatus  Zone  from  the  overlying  P.  fruticosus  Zone.  In  both  regions,  diverse  assemblages 
of  both  dichograptids  (e.g.  Tetragraptus , Didymograptus  ( Expansograptus ),  Pendeograptus , 
Pseudophvllograptus)  and  traditional  ‘dendroid’  taxa  (e.g.  Rhabdinopora , Dendrograptus , Arcantho- 
graptus)  are  present.  Although  three-dimensional,  isolated  material  was  not  recovered  from  this 
interval,  the  representatives  of  Clonograptus  do  indeed  appear  to  bear  more  resemblance  to  the 
dichograptids  than  to  the  anisograptids,  and  we  tend  to  agree  with  the  conclusions  of  Maletz  and 
Erdtmann  (1987).  Erdtmann  et  al.  (1987,  p.  123)  transferred  Clonograptus  smithi  Harris  and 
Thomas,  1938  to  their  new  kinnegraptid  genus  Paradelograptus.  C.  smithi  is,  however,  from  the 
lower  Bendigonian  (equivalent  to  the  T.  approximatus  or  T.  akzharensis  zones)  and  appears  very 
similar  to  C.  rigidus /C.  flexilis. 

If  typical  Clonograptus  belongs  to  the  Dichograptidae,  it  is  unlikely  that  taxa  from  the  lower, 
middle  or  even  upper  Tremadoc  should  be  assigned  to  the  genus  if  the  presence  of  bithecae  or  a 
stolon  system  is  considered  of  taxonomic  significance  at  the  generic  level.  Final  revision  of  the 
generic  definition  should,  however,  be  withheld  until  isolated  material  of  ‘Clonograptus'  has  been 
recovered  from  both  the  Tremadoc  and  lower  Arenig.  We  therefore  here  refer  our  late  Tremadoc 
'Clonograptus- like’  taxa  to  ‘ ClonograptusT 


Clonograptusl  sp.  A. 

Plate  2,  fig.  6;  Plate  6,  figs  16-18;  Plate  7,  figs  1-5;  Text-fig.  15a-f 

Material.  Several  flattened  specimens  from  CHN8.32,  MPS42C  and  GP38.  Ten  isolated,  three-dimensional 
specimens  from  MPS42C. 

Description.  The  rhabdosome  reaches  over  30  mm  in  diameter,  somewhat  irregular,  delayed  dichotomous 
branching  producing  up  to  at  least  thirty-two  stipes  distally  from  the  two  primary  stipes.  The  proximal  region 


40 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  15.  a-f,  Clonograptus  sp.  A,  a and  f x2-5,  b-e  x 5.  a,  GSC  87418,  GP40.  b,  GSC  87342,  MPS42C. 
c,  GSC  87343,  MPS42C.  d,  GSC  87373,  GP38.  E,  GSC  87380,  GP38.  f,  GSC  87344,  MPS42C.  g-i, 
Clonograptus  sp.  C,  x 2-5.  g,  GSC  87351,  MPS42C.  H,  GSC  87346,  MPS42C.  i,  GSC  87419,  GP40.  j, 
Clonograptus  sp.  B,  GSC  87314,  MPS42C,  x 2-5  (also  figured  PI.  2,  fig.  5).  k-n,  Rhabdinopora  sp.,  MPS42C, 
x 5.  K,  GSC  87338.  l,  GSC  87345.  m,  GSC  87352.  n,  GSC  87353. 


EXPLANATION  OF  PLATE  7 

Figs  1-5.  Clonograptus  sp.  A.  MPS42C,  all  x 40  except  Fig.  3 (=  x 20).  1,  GSC  87479.  2,  GSC  87481.  3,  GSC 
87423.  4,  GSC  87470.  5,  GSC  87476. 

Figs  6-12.  Rhabdinopora  sp.  6,  GSC  87451,  SPI43.  7,  GSC  87456,  MPS42C.  8,  GSC  87483,  MPS42C.  9,  GSC 
87452,  SP143.  10,  GSC  87419,  MPS42C.  11,  GSC  87454,  MPS42C.  12,  GSC  87420,  MPS42C.  All  x 40, 
except  fig.  6 ( = x 80). 

Figs  13-17.  Indet.  dendroid  distal  fragments.  13,  GSC  87448,  SPI43.  14  and  15,  GSC  87464,  GP38.  15,  GSC 
87471,  MPS42C.  17,  GC  87480,  MPS42C.  All  x 40  except  fig.  17  ( x 80). 

Scanning  electron  micrographs  of  isolated  specimens. 


PLATE  7 


WILLIAMS  and  STEVENS,  Clonograptus,  Rhabdinopora 


42 


PALAEONTOLOGY,  VOLUME  34 


is  generally  preserved  in  scalariform  view,  with  stipe  widths  of  about  0-7  mm;  distal  stipe  widths  are  similar, 
both  in  scalariform  and  lateral  aspect.  The  stipes  have  an  irregular  appearance  owing  to  the  presence  of 
bithecae  throughout  the  rhabdosome.  Dichotomous  branching  occurs  throughout  the  rhabdosome  at  intervals 
of  2-8  mm;  failed  dichotomies  commonly  result  in  asymmetrical  rhabdosomes. 

The  sicula  is  about  2 mm  long,  with  a distinctive  concave  apertural  outline  formed  by  a prominent  rutellum 
and  slight  antirutellar  process.  Proximal  development  has  not  been  observed  clearly,  but  appears  to  be  similar 
to  most  coeval  graptolites,  with  a prominent  sicular  bitheca  opening  at  the  level  of  divergence  of  the  ventral 
wall  of  th  1 1 from  the  rutellar  margin.  Thl1  and  l2  are  strongly  declined,  giving  a narrow,  pendent  appearance 
to  the  proximal  region.  Their  free  ventral  margins  are  gently  concave  and  are  1-8-2  0 mm  long.  The  funicle  is 
normally  deformed  due  to  flattening  of  the  rhabdosome  in  a plane  perpendicular  to  that  of  the  sicula,  thl 1 and 
l2.  Both  thl2  and  21  dichotomise,  as  do  many  subsequent  thecae,  giving  rise  to  the  multi-stiped  rhabdosome. 

All  autothecae  apparently  possess  bithecae,  opening  on  alternate  sides  of  the  stipes.  The  ventral  margins  of 
autothecae  display  gentle  concave  curvature,  have  simple  apertures  occupying  one  half  to  one  third  total  stipe 
width  and  have  an  almost  uniform  spacing  of  ten  in  10  mm  throughout  the  rhabdosome. 

Remarks.  This  species  appears  to  differ  from  all  described  previously,  but  inadequate  material  exists 
to  justify  formal  erection  of  a new  taxon.  The  overall  appearance  of  the  rhabdosome  and  thecal  style 
is  reminiscent  of  Clonograptus  kingi  Benson  and  Keble,  1935.  Their  species  is,  however,  minute,  with 
slender  stipes  0-2  mm  wide  and  a very  high  thecal  density. 

Both  proximal  and  distal  isolated  fragments  are  extremely  distinctive,  owing  to  their  robust  form, 
ubiquitous  bithecae,  and  curved  autothecae.  Although  very  different  in  proximal  appearance  and 
thecal  style,  it  is  sometimes  difficult  to  distinguish  poorly  preserved  specimens  from  Aorograptus 
victoriae  preserved  in  dorsal  view.  The  latter  species  possesses  more  simple  autothecae,  only  has 
bithecae  at  dichotomies,  and  the  proximal  region  has  a very  different  appearance. 


Clonograptus ? sp.  B. 

Plate  2,  fig.  5;  Text-fig.  15j 

Material.  Two  flattened  specimens  from  MPS42C  and  GP38. 

Remarks.  These  two  specimens  are  preserved  in  scalariform  orientation,  and  characterized  by  heavy 
cortical  thickening  in  the  proximal  region.  This  reduces  distally,  resulting  in  narrowing  stipes. 
Details  of  lateral  stipe  width,  thecal  style,  etc.,  have  not  been  observed  due  to  both  orientation  of 
the  rhabdosome  and  to  the  cortical  thickening. 

Examples  of  ‘ Clonograptus ’ with  similar  appearance  have  been  recorded  several  times  before, 
both  from  the  top  Tremadoc  and  other  stratigraphic  levels.  The  specimen  figured  by  T.  S.  Hall 
(1914,  pi.  8,  fig.  3)  as  ‘C.  tenellus  callavei  Lapworth'  and  refigured  by  Bulman  and  Cooper  (1969, 
fig.  5 i/)  is  probably  identical.  Our  specimens  are  also  similar  in  appearance  to  J.  Hall’s  (1858)  type 
specimens  of  C.  rigidus  and  C.flexilis  regarding  their  distinctive  cortical  thickening,  but  his  material 
from  the  lower  Arenig  of  Quebec  reaches  much  greater  dimensions  and  critical  comparison  is  not 
possible.  If  the  specimens  from  western  Newfoundland  are  indeed  similar  to  Hall’s  types,  it 
demonstrates  that  they  may  be  assigned  unequivocally  to  Clonograptus  s.s. 

Clonograptus ? sp.  C 
Text-fig.  15g-i 

Material.  Several  flattened,  fragmentary  specimens  from  MPS42C  and  GP40. 

Remarks.  These  specimens  are  characterised  by  a funicle  of  varying  width  due  to  irregular, 
commonly  delayed,  first  dichotomous  branching,  relatively  slender  stipes  0-8  mm  wide,  and  simple 
autothecae  numbering  about  eight  in  10  mm.  The  proximal  region  is  gently  declined  and  open,  in 
contrast  with  Clonograptus ? sp.  A.  No  isolated  material  or  well  preserved  flattened  specimens  have 


WILLIAMS  AND  STEVENS:  NEWFOUNDLAND  TREMADOC  GRAPTOLITES 


43 


been  recovered  exhibiting  complete  proximal  development;  it  is  possible  that  Clonograptusl  sp.  C 
is  closer  to  Aorograptus  victoriae  than  to  Clonograptus , but  the  lack  of  flared  apertures  and  overall 
appearance  of  the  proximal  region  appear  to  be  different  from  that  genus. 


Genus  rhabdinopora  Eichwald,  1855 

Type  species.  Gorgonia  flabelliformis  Eichwald,  1840,  p.  207.  By  subsequent  designation  of  Erdtmann  (1982) 

Diagnosis.  Rhabdosome  conical  (juvenile  stages  may  possess  reduced  conicality),  coni-siculate 
throughout  all  developmental  stages,  with  or  without  proximal  buoyancy  structures;  branching 
dichotomous,  diverging  from  tricalycal  or  quadricalycal  initial  stolonal  budding;  stipes  straight, 
subparallel  to  parallel,  connected  by  transverse  dissepiments,  anastomosis  rare;  autothecae 
denticulate,  commonly  spined,  bithecae  normally  inconspicuous  (from  Erdtmann  1982,  pp. 
128-129). 

Remarks.  Erdtmann's  revision  of  Dictyonema  and  Rhabdinopora , restricting  the  former  genus  to 
rooted  species,  is  here  accepted.  Our  planktonic  forms  are  therefore  assigned  to  Rhabdinopora , 
although  previously  they  would  have  been  considered  ‘typical'  Dictyonema. 


Rhabdinopora  sp. 

Plate  2,  figs  7-11,  13;  Plate  7,  figs  6-12;  Text-fig.  15k-n 

Material.  Many  three-dimensional,  isolated  fragments  from  SP143  and  MPS42C,  and  flattened  specimens  from 
all  late  Tremadoc  localities  in  the  Cow  Plead  Group. 

Remarks.  The  genus  Rhabdinopora  is  currently  under  revision  by  Erdtmann  and  others.  Characters 
of  taxonomic  importance  are  still  uncertain,  and  we  withhold  full  taxonomic  treatment  pending 
further  revision  of  the  genus.  Three  primary  stipes  are  clearly  visible  in  isolated  material,  and  the 
slender  sicula  and  proximal  development  are  readily  identifiable  in  flattened  specimens.  A ‘flotation 
sac’  is  present  on  one  of  the  specimens,  while  thecal  style,  dissepiments  and  net-like,  parabolic 
rhabdosome  are  all  characteristic  of  Rhabdinopora. 

This  ubiquitous  form  continues  into  the  lower  Arenig,  where  it  is  common  in  both  the  T. 
approximate  and  T.  akzharensis  zones,  but  rare  after  that  level.  The  disappearance  of  Rhabdinopora 
from  the  sections  may  be  stratigraphically  controlled,  but  in  our  opinion  is  more  likely  related  to 
subtle  changes  in  paleoecology. 


miscellaneous  indet.  Graptoloids 
Plate  2,  fig.  12;  Plate  7,  figs  13  17 

Remarks.  A variety  of  distal  stipe  fragments  are  present  in  the  late  Tremadoc,  flattened  in  the  shale 
and  as  three-dimensional  isolated  fragments  from  dissolved  limestone.  They  are  not  identifiable 
without  additional,  more  complete  material,  but  due  to  their  distinctive  nature  a selection  is  here 
figured  for  completeness. 

Acknowledgements.  Financial  support  for  this  project  was  through  grants  to  S.H.W.,  R.K.S.,  C.  R.  Barnes 
and  N.  P.  James  by  the  Natural  Sciences  and  Engineering  Research  Council,  Energy,  Mines  and  Resources, 
and  Memorial  University  of  Newfoundland.  The  paper  has  benefited  from  extensive  discussion  with  several 
graptolite  workers,  particularly  R.  A.  Fortey,  and  from  comments  made  by  the  referees.  Much  of  our  material 
could  not  have  been  collected  without  the  cooperation  and  issue  of  permits  by  Parks  Canada.  We  are  most 
grateful  to  all  the  above  individuals  and  organisations  for  their  invaluable  assistance. 


44 


PALAEONTOLOGY,  VOLUME  34 


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reproducing  the  effects  of  diagenetic  flattening  on  graptolites.  Lethaia , 15,  365-372. 
williams,  s.  h.  and  stevens,  r.  k.  1987.  Summary  account  of  the  Lower  Ordovician  (Arenig)  graptolite 
biostratigraphy  of  the  Cow  Head  Group,  western  Newfoundland.  Bulletin  of  the  Geological  Society  of 
Denmark , 35,  259-270. 

— I988«.  Early  Ordovician  (Arenig)  graptolites  of  the  Cow  Head  Group,  western  Newfoundland, 

Canada.  Palaeontographica  Canadiana , 5,  1-167. 

— 19886.  Late  Tremadoc  graptolites  from  western  Newfoundland.  1 14.  In  williams,  s.  h.  and  barnes, 
c.  R.  (eds).  Fifth  International  Symposium  on  the  Ordovician  System , Program  and  Abstracts.  St  John’s, 
Newfoundland,  117  pp. 


s.  henry  williams 

ROBERT  K. STEVENS 
Department  of  Earth  Sciences 

Typescript  received  25  September  1989  Memorial  University  of  Newfoundland 

Revised  typescript  received  24  November  1989  St  John’s,  Newfoundland  A1B  3X5,  Canada 


MIDDLE  TRIASSIC  HOLOTHURIANS  FROM 
NORTHERN  SPAIN 

by  ANDREW  B.  SMITH  Cllld  J.  GALLEMI 


Abstract.  An  abundant  fauna  of  well-preserved  holothurians  is  described  from  the  Middle  Triassic  (Ladinian) 
of  Collbato,  northern  Spain.  Three  new  genera  and  species  are  represented,  Strobilothyone  rogenti , a 
heterothyonid,  Monilipsolus  mirabilis , a psolid,  and  Collbatothuria  danieli  an  aspidochirote  of  uncertain  familial 
affinities.  A new  subfamily,  Monilipsolinae,  is  created  for  Monilipsolus.  Holothurians  had  clearly  achieved 
considerable  diversity  by  the  Middle  Triassic;  at  least  four  of  the  six  currently  recognized  orders  were 
established  by  this  time.  Holothurians  were  also  ecologically  diverse  by  the  Middle  Triassic  with  epibenthic, 
deposit-feeding  species,  infaunal,  suspension-feeding  species  and  epifaunal,  attached,  suspension-feeding 
species  all  represented. 

Of  the  five  classes  of  echinoderm  alive  today,  none  has  a poorer  fossil  record  than  the  holothurians. 
There  are  some  1 160  named  species  alive  today  (Pawson  1982),  and  these  are  found  in  virtually  all 
marine  habitats.  Yet  only  a handful  of  complete  specimens  of  fossil  holothurians  have  ever  been 
discovered.  This  is  partially  explained  by  the  relatively  low  fossilization  potential  of  holothurians, 
since  the  great  majority  have  their  skeleton  reduced  to  microscopic  spicules.  However,  the 
holothurian  fossil  record  is  considerably  worse  than  might  be  expected.  For  example,  although 
several  families  of  dendrochirotids  possess  an  imbricate  skeleton  of  large  calcite  plates  and  might 
be  expected  to  be  preserved  in  Konservat  Lagerstatten,  none  has  ever  been  reported  as  fossils. 
Complete  fossil  holothurians  have  been  reported  from  just  six  localities: 

1.  Hunsriickschiefer,  Lower  Devonian  of  Budenbach,  West  Germany.  This  has  yielded  seven 
specimens  of  Palaeocucumaria  hunsrueckiana  Lehmann,  described  by  Seilacher  (1961). 

2.  Francis  Creek  Shale,  Middle  Pennsylvanian  of  Illinois,  USA.  Over  two  thousand  specimens 
of  an  Achistrum  sp.,  only  a preliminary  description  of  which  has  so  far  been  published  (Sroka  1988). 

3.  Muschelkalk,  Middle  Triassic,  of  Tarragona,  Spain.  One  specimen  each  of  the  elasipod 
Oneirophantites  tarragonensis  Cherbonnier  and  the  aspidochirote  Bathysynactites  viai  Cherbonnier, 
preserved  as  impressions  in  calcareous  silts  (Cherbonnier  1978). 

4.  Upper  Hauptrogenstein,  Upper  Bajocian,  Middle  Jurassic  of  Schinznach,  Switzerland.  A 
single  specimen  of  the  stichopid  Holothuriopsis  pawsoni  Hess  (Hess  1973)  which  preserves  body  wall 
spiculation  but  little  else. 

5.  Solenhofen  Limestone,  Kimmeridgian,  Upper  Jurassic  of  Solenhofen,  West  Germany.  Two 
species  have  been  identified  as  holothurians,  Proholothuria  armata  Giebel  and  Pseudocaudina 
brachyura  Broili,  the  latter  based  on  a single  specimen  (Frizell  and  Exline  1966).  P.  armata  is  a 
worm-shaped  fossil  that  shows  no  details  and  is  indeterminate  to  phylum.  P.  brachyura  shows 
longitudinal  banding  and  might  be  a holothurian,  though  Hess  (1973)  has  questioned  this. 

6.  Lower  Cretaceous  (Albian)  of  Tepexi  de  Rodriguez,  Puebla,  Mexico.  A complete  holothurian 
is  recorded  from  here  (Seibertz  1988),  but  no  description  of  this  has  yet  been  published. 

The  lack  of  complete  specimens  creates  major  problems  in  investigating  the  evolutionary  history 
of  holothurians.  Holothurian  spicules  are  relatively  common  as  microfossils  and  a parataxonomy 
has  been  established  on  spicule  morphology  alone  (e.g.  Frizell  and  Exline  1955,  Deflandre-Rigaud 
1962).  However,  this  may  bear  little  correlation  with  natural  biological  groupings  and  it  is  difficult 
to  deduce  much  about  the  mode  of  life  of  extinct  holothurians  from  spicule  morphology.  Further 
problems  arise  because  higher  taxa  of  holothurians  are  defined  to  a large  degree  on  soft  tissue 


IPalaeontology,  Vol.  34,  Part  1,  1991,  pp.  49-76,  5 pls.| 


© The  Palaeontological  Association 


50 


PALAEONTOLOGY,  VOLUME  34 


anatomy,  such  as  the  shape  of  the  feeding  tentacles  or  the  arrangement  of  gonads,  characters  that 
are  unknown  even  in  those  few  fossil  species  preserved  as  complete  specimens.  Complete  fossil 
holothurians  can,  however,  generally  be  placed  within  a biological  classification  and  provide  direct 
information  about  the  ecological  diversification  of  the  group. 

The  discovery  of  a new  assemblage  of  well-preserved  fossil  holothurians  belonging  to  three 
families  from  the  Middle  Triassic  of  Catalonia,  north-east  Spain  is  thus  totally  unexpected.  The 
locality  was  discovered  in  1986  when  David  Brusi,  a lecturer  at  the  Teacher’s  College  of  the 
Universidad  Autonoma  de  Barcelona,  collected  two  ophiuroids  from  a disused  limestone  quarry  at 
Pedrera  d'en  Rogent.  These  specimens  were  shown  to  one  of  us  (J.G.)  who  later  visited  the  locality 
with  Brusi.  On  this  trip  several  fossil  holothurians  were  found  and  photographed  but  not  collected 
because  it  was  felt  that  this  was  a difficult  operation  and  required  a portable  rock-saw.  A second 
visit  by  J.G.  was  made  in  November  1987,  equipped  with  power  tools,  and  many  fossil  holothurians 
were  collected  together  with  other  fossils.  Just  prior  to  this  second  visit  a number  of  specimens  had 
been  collected  from  this  quarry  by  an  amateur  palaeontologist.  Dr  Daniel  Gutierrez.  The 
ophiuroids  collected  by  him  were  later  described  (Calzada  and  Gutierrez  1988)  but  the  holothurians 
were  given  to  us  for  study.  A preliminary  account  of  this  holothurian  fauna  was  presented  at  the 
Fourth  Annual  Meeting  of  the  Spanish  Palaeontological  Society  in  Salamanca  (Gallemi  1990). 
Supplementary  material  has  been  collected  subsequently  from  this  quarry  in  February  1989  by  J.G. 


LOCALITY  AND  GEOLOGICAL  SETTING 

The  holothurians  described  here  come  from  a steeply  dipping  bedding  surface  in  an  abandoned 
limestone  quarry  locally  known  as  'La  Pedrera  d’en  Rogent’  (Rogent’s  quarry),  some  200  metres 
east  of  the  village  of  Collbato,  Catalonia,  north-eastern  Spain  (Text-fig.  1).  It  is  Middle  Triassic  in 
age  and  represents  the  most  westerly  outcrop  of  Triassic  in  the  Llobregat  River  area.  Collbato  is 
situated  in  the  'Pre-littoral  Range’,  the  innermost  of  the  three  tectonic  belts  into  which  the  Catalan 
Mountain  Ranges  are  divided;  the  others  being  the  Valles-Penedes  Depression  and  the  Littoral 
Range  (Text-fig.  I ).  In  the  region  of  Collbato  the  succession  is  tectonically  complex. 

The  Triassic  of  this  region  overlies  Palaeozoic  basement  and  resembles  the  succession  seen  in 
southern  Germany  with  Buntsandstein  facies  succeeded  by  Muschelkalk  facies.  Three  units 
(M 1-M3)  are  recognized  within  the  Muschelkalk  here.  The  upper  and  lower  units  (M 1 and  M3)  are 
carbonates  clearly  of  marine  origin,  while  the  middle  unit  (M2)  is  composed  mainly  of  sandstones 
and  clays  of  continental  facies.  Masachs  (1981)  had  previously  suggested  that  beds  equivalent  to 
those  at  La  Pedrera  d'en  Rogent  belong  to  the  Ml  unit  (Anisian).  However,  in  the  most  recent 
geological  mapping  of  this  region  (Rosell  et  at.  1975),  the  outcrop  at  Collbato  was  placed  within  unit 
M3  (Ladinian)  and  Calzada  and  Gutierrez  (1988)  accepted  a Ladinian  age  for  the  echinoderm  fossil 
horizon.  The  holothurian  horizon  corresponds  to  the  La  Riba  Reef  Formation  (F.  Calvet,  personal 
communication,  July,  1989)  and  is  indeed  Ladinian. 

Associated  fauna  at  this  horizon  include  sponges,  indeterminate  internal  moulds  of  gastropods, 
bivalves,  and  ammonids,  echinoids  (some  with  spines  attached)  and  crinoids.  Isolated  vertebrae  and 
a single  tooth  have  also  been  found.  The  crinoid  is  a species  of  Encrinus  in  which  the  lowest  six  or 
seven  secundibrachs  are  uniserially  arranged.  It  comes  closest  to  E.  aculeatus  Meyer,  from  the 
Lower  Muschelkalk  of  Germany.  The  echinoid  test  material  all  belongs  to  Miocidaris  sensu  stricto 
and  the  associated  spines  are  of  three  forms  attributable  to  ' Cidaris ’ wissmanni  Bather  [C.  roemeri 
of  Jekehus  (1936)  and  Mihaly  (1981)],  ‘C.  ’ ecki  Assmann  and  a smooth-shafted,  slightly  fusiform 
spine  of  uncertain  affinity.  All  are  relatively  long-ransing  morphotypes  in  the  Middle  Trissic  (Smith 
1990). 

At  La  Pedrera  d’en  Rogent  16-20  metres  of  micritic,  finely  laminated,  almost  lithographic, 
limestones  with  more  marly  intercalations  are  exposed.  The  section  includes  at  least  one  layer 
covered  in  the  trace  fossil  Fucoides  and  several  thin  levels  of  bioclastic  limestone,  composed  largely 
of  echinoderm  debris.  Sedimentary  structures  are  limited  to  some  megaripples  and  some  scour 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHURIANS 


51 


text-fig.  I.  Map  showing  the  fossil  localities  dis- 
cussed in  the  text  and  their  regional  setting.  1, 
regional  setting  and  location  of  map  2.  2,  Barcelona 
region  showing  position  of  map  3.  3,  simplified 
geological  map  of  the  Collbato  district  showing  the 
fossil  localities  (stars)  that  have  yielded  holothurians : 
P = La  Pedrera  d’en  Rogent;  R = El  Pujolet; 
T = Tertiary;  Q = Quaternary;  B = Buntsandstein 
(Lower  Triassic);  M 1-3  = Lower,  Middle  and  Upper 
Muschelkalk  (Middle  Triassic).  Simplified  from 
Rosell  et  al.  (1975). 


troughs  associated  with  bioclastic  influx.  The  detailed  succession  is  very  difficult  to  follow  because 
of  the  dense  network  of  small-scale  faults  that  cross-cuts  the  quarry. 

Most  of  the  holothurians  come  from  bedding  planes  that  are  covered  in  sponges  distributed  as 
small  rounded  discs  or  as  more  continuous  mats  (PI.  1,  fig.  1).  The  palaeoenvironment  of  these 
precise  beds  has  not  been  investigated,  but  Calvet  et  al.  (1987)  and  Calvet  and  Tucker  (1988)  have 
interpreted  the  palaeoenvironmental  setting  of  the  La  Riba  Reef  facies  as  representing  deposition 
in  relatively  tranquil  marine  habitat  below  fair  weather  wave-base  on  an  intracratonic  carbonate 
ramp. 

A second  quarry,  ‘El  Pujolet’  lies  just  to  the  north  west  of  the  village  of  Collbato  (Text-fig.  1). 
Here  a steeply-dipping  bedding  surface  covered  in  Fucoides  dominates  nearly  all  of  the  quarry  face. 
Encrinus  and  ophiuroids  have  been  collected  from  here,  but  as  yet  only  a single  articulated 
holothurian  ( Strobi/othyone  rogenti)  has  been  found. 


SYSTEMATIC  PALAEONTOLOGY 

Class  HOLOTHUROIDEA 
Order  dendrochirotida  Grube,  1840 
Family  heterothyonidae  Pawson,  1970 

Diagnosis.  Body  completely  covered  in  plates  lacking  spires;  spicules  in  the  form  of  cups  may  also 
be  present.  Plates  not  pierced  for  tube  feet.  Mouth  anterior,  anus  at  end  of  a posterior  tail. 
Calcareous  ring  composed  of  five  radial  and  five  interradial  elements;  radial  elements  not 
composite,  with  well  developed  posterior  processes. 


52 


PALAEONTOLOGY,  VOLUME  34 


Type  genus  and  species.  Heterothyone  cdba  (Hutton),  from  fine  sands  or  muds  around  New  Zealand  and  the 
Chatham  Islands  [Recent], 

Tax  a included.  Strobilothyone  rogenti  sp,  nov.  [Middle  Triassic,  Spain];  Heterothyone  ocnoides  (Dendy) 
[Recent,  New  Zealand], 

Remarks.  S.  rogenti  clearly  belongs  to  the  Dendrochirotida  because  of  its  well  developed  calcareous 
ring  and  complete  body  covering  of  imbricate  plates  lacking  spires.  Pawson  (1982)  recognized 
several  extant  families  within  this  order.  Three  of  these  (Phyllophoridae,  Sclerodactylidae  and 
Cucumariidae)  are  soft  bodied  with  their  skeleton  reduced  to  microscopic  spicules.  In  addition  the 
former  two  have  complex  calcareous  rings  that  are  made  up  of  a mosaic  of  plates,  unlike  that  of 
Strobilothyone.  The  four  remaining  families  all  possess  a skeleton  of  large  imbricate  plates  as  does 
Strobilothyone.  Psolidae  are  very  easily  distinguished  because  their  mouth  is  displaced  dorsally  and 
they  have  a differentiated  sole  that  is  uncalcified : Strobilothyone  clearly  does  not  belong  to  that 
family.  Paracucumidae  are  fully  plated  and  cylindrical  in  shape  but  unlike  Strobilothyone  have  a 
simple  calcareous  ring  lacking  posterior  processes  and  their  plates  are  spired.  Placothuriidae  are 
also  fully  plated  and  cylindrical  in  shape  like  Strobilothyone , but  their  calcareous  ring  is  very 
different.  Radial  elements  of  the  calcareous  ring  in  Placothuriidae  have  long  posterior  processes  that 
are  composed  of  a mosaic  of  small  plates.  S.  rogenti  comes  closest  to  members  of  the  family 
Heterothyonidae.  Heterothyonids  have  simple  well-defined  posterior  processes  on  the  radial 
elements  of  the  calcareous  ring  that  are  only  slightly  shorter  than  those  seen  in  S.  rogenti.  They  are 
cylindrical  in  form  and  fully  plated  with  a slightly  differentiated  anal  tail  (Pawson  1970,  pi.  1,  figs 
2 and  3).  The  family  contains  only  two  living  species,  placed  in  a single  genus,  Heterothyone.  The 
principal  difference  between  Heterothyone  and  Strobilothyone  is  that  in  Heterothyone  there  are 
microscopic  ossicles  in  the  form  of  cups  overlying  the  plates  of  the  body  wall.  Cups  are  absent  in 
Strobilothyone , which  may  represent  the  primitive  condition.  It  is  worth  noting  that  in  a closely 
related  family,  Placothuriidae,  there  are  two  species  of  Placothuria , one  with  scales  overlain  by 
microscopic  buttons  (P.  huttoni  (Dendy))  and  the  other  lacking  buttons  (P.  squamata  Pawson). 
Thus  the  presence  of  microscopic  sclerites  in  addition  to  body  wall  plating  appears  to  be  a character 
of  low  taxonomic  value. 


Genus  strobilothyone  nov. 

Derivation  of  name.  From  the  Latin  strobilus  a pine-cone,  in  allusion  to  its  superficial  appearance. 

Diagnosis.  Body  plates  1-2  mm  broad  and  undifferentiated;  no  cup  deposits  present.  Mouth 
directed  ventrally.  Anus  pentagonal,  situated  on  a posterior  tail.  Radial  elements  of  calcareous  ring 
with  deep  anterior  notch;  posterior  processes  longer  than  rest  of  ossicle. 

Type  species.  Strobilothyone  rogenti  sp.  nov. 

Age.  Ladinian,  Middle  Triassic. 

Taxonomic  remarks.  Strobilothyone  has  a very  similar  calcareous  ring  structure  to  Heterothyone , but 
differs  in  having  a deeper  anterior  notch  in  radial  elements  and  slightly  longer  posterior  processes. 


explanation  of  plate  1 

Preservational  style  of  holothurians  from  the  Ladinian  at  La  Pedrera  d'en  Rogent,  Collbato,  MGB  32383,  x 1. 
There  are  eleven  specimens  of  Strobilothyone  rogenti  gen.  et  sp.  nov.,  including  the  holotype  (arrowed),  and 
a single  specimen  of  Collbatothuria  danieli , gen.  et  sp.  nov.  (C).  Small  oval  masses  of  sponge  cover  the 
surface. 


PLATE  1 


SMITH  and  GALLEMI,  Strobilothyone , Collbatothuria 


54 


PALAEONTOLOGY,  VOLUME  34 


The  principal  difference  between  these  two  genera  is  in  the  complete  absence  of  any  spicular  deposits 
in  addition  to  the  plates  in  Strobilothyone.  In  Heterothyone  cup-elements  are  present  in  the  body 
wall  (Pawson,  1970,  text-fig.  3).  Furthermore,  in  Strobilothyone , the  mouth  appears  to  be  directed 
slightly  ventrally,  rather  than  being  terminal  as  in  Heterothyone. 

Functional  morphology  and  mode  of  life.  This  holothurian  has  an  elongate  body  form  with  a distinct 
caudal  process  which  was  apparently  retractable,  since  it  is  not  seen  in  contracted  specimens.  The 
mouth  and  anus  open  at  opposite  poles  and  papillae  and  other  projections  are  entirely  wanting.  The 
smooth  vermiform  appearance,  lack  of  a clearly  differentiated  sole  and  tube  feet  and  the  apical 
position  of  the  mouth  all  suggest  that  Strobilothyone  was  an  infaunal  holothurian.  Furthermore,  the 
fact  that  plates  imbricate  in  two  directions  (i.e.  towards  the  mouth  anteriorly  and  towards  the  anus 
posteriorly)  strongly  suggests  that  Strobilothyone  was  U-shaped,  since  this  is  precisely  the  condition 
seen  in  modern  U-shaped  heterothyonids  and  placothuriids  (D.  L.  Pawson,  personal  com- 
munication, August,  1989).  Thus  Strobilothyone  probably  lived  much  like  many  modern 
heterothyonids  with  both  anterior  and  posterior  extremities  projecting  from  the  sediment  (Pawson 
1982).  Feeding  tentacles  must  have  been  well  developed,  to  judge  from  the  calcareous  ring,  and 
Strobilothyone  was  presumably  an  infaunal,  benthic,  suspension-feeder.  None  of  the  specimens, 
however,  is  preserved  in  inferred  life  position,  nor  is  there  any  evidence  of  possible  holothurian 
burrows  at  this  horizon. 


Strobilothyone  rogenti  sp.  nov. 

Plate  1,  fig.  1;  Plate  2,  figs  1-5;  Plate  3,  figs  1-3;  Text-figs  2-6 

Types.  Holotype  MGB  32383  (PI.  1,  fig.  1,  arrowed;  PI.  2,  fig.  1)  paratypes  MGB  30556,  30578,  30562,  32320, 
32322,  32336,  32338,  32372,  BMNH  E27540-1. 

Other  material  studied.  MGB  30563,  30564  (sectioned),  30566,  30573,  30679-82,  30684  (sectioned),  32321, 
32357,  32361,  32364,  32366. 

Age  and  distribution.  Middle  Triassic,  Ladinian,  known  from  La  Pedrera  d’en  Rogent  and  El  Pujolet,  near 
Collbato,  Catalonia,  north-eastern  Spain. 

Diagnosis.  As  for  the  genus. 

Description.  Individuals  are  up  to  30  mm  in  length  and  are  fusiform  in  shape,  the  widest  point  being  about  mid- 
length in  most  cases.  The  posterior  tends  to  be  more  pointed  than  the  anterior  (PI.  2,  figs  3 and  4;  PI.  3,  fig. 
3).  Some  individuals  (PI.  2,  fig.  1 ; Text-fig.  2)  have  a distinct  caudal  appendage  which  is  considerably  narrower 
than  the  rest  of  the  body.  This  is  at  most  only  25  % of  the  total  length  of  the  body  and  is  absent  in  obviously 
contracted  specimens  (PI.  3,  fig.  1 ; Text-fig.  3).  Contracted  specimens  are  circular  in  cross-section  and  there  is 
no  differentiated  sole.  Maximum  diameter  ranges  from  about  30-70%  of  the  length. 

The  entire  body  is  sheathed  in  imbricate  plates  up  to  2 mm  wide,  0-6  mm  in  length  and  about  0-1  mm  in 
thickness.  These  plates  are  tightly  stacked  in  contracted  specimens  (Text-fig.  3)  but  show  much  less  overlap  in 
extended  specimens  (Text-fig.  2).  They  appear  to  be  only  two  or  three  stereom  layers  thick.  Most  specimens 


EXPLANATION  OF  PLATE  2 

Figs  I -5.  Strobilothyone  rogenti  gen.  et  sp.  nov.  1,  MGB  32383  (specimen  arrowed  in  PI.  1,  fig.  1),  holotype, 
x 4 (see  Text-fig.  2 for  interpretation).  2,  MGB  30562,  paratypes,  x 4 (see  also  Text-fig.  3);  note  the  change 
in  the  direction  of  imbrication  between  the  oral  and  anal  poles.  3,  MGB  32338,  paratype,  almost  complete 
specimen  showing  anal  appendage  in  contracted  state,  x 2.  4,  MGB  32372,  paratype,  a juvenile,  x 4.  5,  MGB 
32320,  paratype,  showing  calcareous  ring  in  side  view,  x4  (see  Text-fig.  4 for  interpretation). 

All  specimens  from  the  Ladinian,  Middle  Triassic  at  La  Pedrera  d'en  Rogent,  Collbato,  north-eastern  Spain. 


PLATE  2 


SMITH  and  GALLEMI,  Strobilothyone 


56 


PALAEONTOLOGY,  VOLUME  34 


POSTERIOR 


ANTERIOR 


Calcareous  ring 
Mouth 


text-fig.  2.  Strobilothyone  rogenti  gen.  et  sp.  nov., 
MGB  32383;  camera  lucida  drawing  of  the  holotype 
(see  also  PI.  2,  tig.  1).  Relatively  uncontracted 
specimen  in  ventral  view  showing  anal  appendage. 


SMITH  AND  GALLEMf:  MIDDLE  TRIASSIC  HOLOTHURIANS 


57 


text-fig.  3.  Strobilothyone  rogenti  gen.  et  sp.  nov.,  MGB 
30562;  camera  lucida  drawing  of  paratype  (see  PI.  2,  fig.  2). 
Specimen  in  contracted  state. 


Anterior 


show  a change  in  the  sense  of  imbrication  about  mid-length,  plates  towards  the  anterior  imbricate  backwards 
while  those  in  the  posterior  half  imbricate  towards  the  anterior  (PI.  2,  fig.  2;  PI.  3,  fig.  3;  Text-figs  2 and  3). 
The  plating  close  to  the  anus  becomes  virtually  pentagonal  in  some  specimens  (PI.  3,  fig.  1 ; Text-fig.  6) 
suggesting  that  there  might  be  a pentagon  of  internal,  anal  valve  plates  making  this  region  more  rigid.  No 
other  spicules  are  associated  with  the  body  wall. 

The  calcareous  ring  is  seen  in  MGB  30578  (PI.  3,  fig.  2)  and  MGB  32320  (PI.  2,  fig.  5).  It  consists  of  ten 
elements,  five  radial  and  five  interradial  pieces  (Text-figs  4 and  5).  The  radial  pieces  are  the  larger  and  have  both 
anterior  and  posterior  processes.  Anterior  processes  are  relatively  short  and  two  or  three  in  number.  The 
posterior  processes  are  much  longer,  forming  more  than  half  of  the  radial  length  of  the  ossicle.  There  are  two 
processes  to  each  element  and  these  are  simple.  The  interradial  pieces  are  as  broad  as  the  radial  pieces  but  lack 
posterior  processes.  They  have  a small  central  anterior  projection  and  possibly  an  adjacent  anterior  notch. 

A small  plate  about  0-3  mm  in  diameter  with  a spongy  appearance  is  seen  close  to  the  calcareous  ring  in 
MGB  30578  (Text-fig.  5).  This  may  be  the  madreporite. 


Family  psolidae  Perrier,  1902 

Diagnosis.  Plated  dendrochirotes  with  a differentiated  sole  and  both  mouth  and  anus  opening  on 
the  dorsal  surface.  Calcareous  ring  simple;  radial  elements  with  shallow  anterior  notch  but  without 
posterior  processes. 


58 


PALAEONTOLOGY,  VOLUME  34 


Subfamily  monilipsolinae  nov. 

Diagnosis.  Body  oval  in  outline  and  flattened,  with  double  marginal  row  of  stout,  perforate  bead- 
like ossicles  arranged  radially.  No  oral  valve  plates. 

Type  species.  Monilipsolus  mirabilis  sp.  nov. 

Age.  Middle  Triassic,  Ladinian. 

Remarks.  This  subfamily  is  erected  for  the  new  species  Monilipsolus  mirabilis.  It  is  fully  plated  with 
differentiated  dorsal  and  ventral  plating,  the  ventral  surface  taking  the  form  of  a sole.  In  general 
body  organization  it  closely  resembles  extant  psolid  dendrochirotes,  having  the  mouth  displaced 
dorsally  and  the  anus  also  dorsal  and  at  the  end  of  a short  tail.  The  calcareous  ring  of  Monilipsolus 
resembles  that  of  living  psolids,  being  composed  of  radial  and  interradial  elements  that  are 
moderately  stout  and  lack  posterior  processes.  The  presence  of  an  almost  complete  plated 
integument  over  the  peristome  and  a solid  calcareous  ring  suggests  that  Monilipsolus  possessed  an 
introvert  and  could  withdraw  its  tentacles.  Monilipsolus  differs  from  extant  psolids  in  having  a 
strongly  calcified  sole  and  in  having  a remarkable  double  ring  of  stout,  perforate,  bead-like  ossicles 
around  the  periphery.  This  last  character  easily  distinguishes  Monilipsolis  from  all  extant  species  of 
Psolidae  and  is  an  excellent  autapomorphy  for  the  subfamily. 

Genus  monilipsolus  nov. 

Derivation  of  name.  From  the  Latin  monile , a necklace,  in  allusion  to  the  appearance  of  the  peripheral  band 
of  bead-like  ossicles. 

Type  species.  Monilipsolus  mirabilis  sp.  nov. 

Age.  Middle  Triassic,  Ladinian. 

Diagnosis.  Body  oval,  up  to  55  mm  in  length  and  about  |rd  as  wide;  depressed.  Sole  of  thin 
imbricate  plates;  dorsal  surface  of  thicker  plates  with  two  irregular  biserial  bands  of  single  pores 
perforating  plates.  Tube-feet  absent  from  sole  but  probably  present  around  margin.  Peristome  large, 
occupying  most  of  the  anterior  end  of  the  dorsal  surface,  largely  covered  by  a peristomial  membrane 
of  radially-arranged  plates.  Periproct  at  end  of  small  tail.  Well  developed  anterior  notch  on  radial 
elements  of  calcareous  ring. 

Description.  See  description  of  M.  mirabilis  below. 

Remarks.  Monilipsolus  is  a most  remarkable  holothurian  genus.  No  other  holothurian  possesses  any 
structure  comparable  with  the  large  perforate  calcite  ossicles  that  rim  the  body.  The  function  of 
these  ossicles  is  unknown.  It  seems  probable  that  Monilipsolus  was  a suspension  feeder,  like  modern 
psolids,  since  it  has  a dorsally  directed  mouth  and  ventral  sole  for  attachment.  The  large  size  of  the 


EXPLANATION  OF  PLATE  3 

Figs  1-3.  Strobilothyone  rogenti  gen.  et  sp.  nov.  1,  MGB  32322  (paratype),  juvenile  (see  also  Text-fig.  6).  2, 
MGB  30578  (paratypes);  two  specimens,  the  lower  of  which  shows  part  of  the  calcareous  ring  (see  Text-fig. 
5).  3,  MGB  30556  (paratype).  All  x4. 

Fig.  4.  Collbatothuria  danieli  gen.  et  sp.  nov.,  MGB  32274  (paratype),  x3  (see  also  Text-fig.  18). 

All  specimens  from  the  Ladinian,  Middle  Triassic  at  La  Pedrera  d’en  Rogent,  Collbato,  north-eastern  Spain. 


PLATE  3 


SMITH  and  GALLEMI,  Strobilothyone , Collbatothuria 


60 


PALAEONTOLOGY,  VOLUME  34 


ANTERIOR 
IR  R IR  R 


Calcareous  ring 


text-fig.  4.  Strobilothyone  rogenti  gen. 
et  sp.  nov.,  MGB  32320;  camera  lucida 
drawing  of  paratype  (see  PI.  2,  fig.  5). 
Anterior  portion  showing  the  calcareous 
ring  elements  in  side  view;  note  the  apical 
position  of  the  mouth. 


text-fig.  5.  Strobilothyone  rogenti  gen.  et  sp.  nov., 
MGB  30578;  paratype:  camera  lucida  drawings  of 
calcareous  ring  elements  in  a partially  disarticulated 
specimen,  a,  lateral  aspect  showing  two  radial  (R)  and 
one  interradial  (IR)  elements,  b,  same  in  more  anterior 
aspect.  Both  to  same  scale. 


posterior  processes 


1 mm 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHURIANS 


61 


text-fig.  6.  Strobilothyone  rogenti  gen.  et  sp.  nov., 
MGB  32322;  paratype.  Camera  lucida  drawing  of  the 
posterior  region  showing  the  anus  and  the  pentagonal 
arrangement  of  plates  surrounding  it  (see  PI.  3.  fig.  1). 


anus 


text-fig.  7.  Monilipsolus  mirabilis  gen.  et  sp.  nov.,  MGB  32385,  holotype;  dorsal  surface,  x 8.  See  Text-fig.  8 

for  an  interpretation. 


peristome,  the  fact  that  it  is  mostly  covered  by  a flexible  plated  membrane,  and  the  presence  of  a 
well  developed  calcareous  ring  whose  radial  elements  have  deep  anterior  notches  for  the  attachment 
of  tentacle  retractor  muscles  all  point  to  there  being  an  introvert;  the  tentacles  could  presumably 
have  been  more  or  less  fully  retracted  and  protected  by  the  peristomial  plated  membrane.  The 
periproct  lies  on  the  dorsal  surface  at  the  end  of  a short  tail.  The  flattened  profile  and  broad, 
differentiated  sole  suggest  that  Monilipsolus  was  adapted  to  grip  onto  firm  or  hard  bottoms.  Oral 
tube-feet  may  have  been  present  but  uncalcified,  or  might  have  been  absent;  none  is  preserved. 
However,  there  are  rather  large  circular  spaces  found  around  the  periphery  of  the  sole,  adjacent  to 
each  perforate  ball,  which  might  mark  the  sites  of  large  tube-feet  (Text-figs  13  and  14).  Tube  feet 
were  definitely  present  dorsally,  but  were  small  and  have  not  been  preserved.  There  are  two  irregular 
bands  of  small  perforations,  about  01  mm  in  diameter,  on  dorsal  plates  that  run  along  the  length 
of  the  animal  (Text-fig.  12)  and  which  mark  the  site  of  the  tube  feet. 

Thus  in  general  body  organization  and  mode  of  life  Monilipsolus  closely  resembles  modern  psolid. 
suspension  feeders  which  cling  to  pebbles  and  other  such  solid  substrata. 

The  stout  perforate  ossicles  that  form  a marginal  rim  to  Monilipsolus  are  unique  and  of  unknown 
function.  These  are  sometimes  slightly  faceted  to  fit  closely  together  and  are  developed  around  the 


62 


PALAEONTOLOGY,  VOLUME  34 


anterior 


marginals 


sole 


POSTERIOR 


text-fig.  8.  Monilipso/us  mirabilis  gen.  et  sp,  nov., 
camera  lucida  drawing  of  MGB  32385  (holotype), 
dorsal  aspect  (see  Text-fig.  7). 


entire  periphery,  without  a break.  The  perforations  are  narrow,  05-06  mm  in  diameter  in  ossicles 
1-5-1 -6  mm  in  diameter  and  expand  slightly  towards  the  interior.  The  interior  opening  of  these  pores 
lies  within  the  body  cavity,  inside  the  plated  mesoderm,  and  so  must  have  connected  to  some 
internal  coelom  or  organ.  The  exterior  opening  is  directed  laterally  and  slightly  downwards 
(ventrally),  so  that  it  is  generally  not  seen  in  dorsal  view  and  can  just  be  seen  in  ventral  view. 

The  functional  significance  of  this  peripheral  ring  of  perforate  ossicles  can  be  assessed  by 
considering  its  possible  role  with  respect  to  the  various  vital  functions  that  a holothurian  must 
perform.  These  are  to  do  with  feeding,  sensory  reception,  defence,  locomotion/adhesion, 
reproduction  and  respiration. 

It  seems  highly  improbable  that  the  perforate  ossicles  played  any  part  in  feeding  since  they  are 
well  removed  from  the  mouth  and  digestive  tract.  Comparative  morphology  suggests  that 
Monilipsolus  fed  using  tentacles,  like  psolids. 


EXPLANATION  OF  PLATE  4 

Figs  1-3.  Monilipsolus  mirabilis  gen.  et  sp.  nov.  1,  MGB  32367  (paratypes);  both  individuals  show  dorsal 
surfaces  (incomplete),  the  upper  is  illustrated  in  Text-fig.  11.  2,  MGB  30671  (paratype),  dorsal  surface 
showing  tube  foot  pores  (see  also  Text-fig.  12).  3,  MGB  32325  (paratype),  dorsal  surface,  mouth  to  the  left 
(see  Text-fig.  10  for  interpretation).  All  x3. 

All  specimens  from  the  Ladinian,  Middle  Triassic  at  La  Pedrera  d'en  Rogent,  Collbato,  north-eastern  Spain. 


PLATE  4 


SMITEI  and  GALLEMI,  Monilipsolus 


64 


PALAEONTOLOGY,  VOLUME  34 


mouth 


marginals 


ANTERIOR 


text-fig.  9.  Monilipsolus  mirabilis  gen.  et 
sp.  nov.,  camera  lucida  drawing  of  BMNH 
E27543;  paratype  (see  PI.  5,  fig.  2).  Dorsal 
surface. 


marginals 


anal 

cone 


1 mm 

i — 


POSTERIOR 


They  are  also  almost  certainly  not  associated  with  reproduction,  simply  because  of  their 
multiplicity  and  distribution  around  the  entire  periphery.  In  holothurians  the  gonads  open  through 
a single  pore  close  to  the  tentacle  ring.  No  holothurian  has  multiple  gonopore  openings  and  their 
distribution  and  orientation  are  difficult  to  explain  in  functional  terms. 

Gaseous  exchange  is  another  possible  function.  The  pores  would  then  be  inhalant  or  exhalant  (or 
both)  orifices  through  which  sea  water  would  be  drawn  inside  the  mesodermal  skeleton  to  allow 
efficient  gaseous  exchange,  presumably  across  a thin  membrane.  Although  some  Palaeozoic  cystoids 
have  developed  a comparable  system,  no  holothurian  is  known  that  has  any  system  remotely 
comparable.  Furthermore,  the  positioning  of  the  pores  around  the  periphery  of  the  animal  pointing 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHU RIANS 


65 


text-fig.  10.  Monilipsolus  mirabilis 
gen.  et  sp.  nov.,  camera  lucida 
drawing  of  MGB  32325;  paratype 
(see  PI.  4,  fig.  3).  Dorsal  aspect. 


ANTERIOR 


ambulacral  pores 


anus 


marginals 


mouth 


slightly  downwards  would  only  make  sense  if  these  were  exhalant  orifices  and  no  obvious  inhalant 
orifice  can  be  identified.  We  do  not  favour  this  interpretation. 

They  cannot  be  locomotory  in  function,  because  they  have  no  articulation  at  the  base  and  seem 
to  fit  together  very  closely,  often  being  slightly  facetted.  The  perforations  might  conceivably  be 
associated  with  some  form  of  secretion  to  enhance  adhesion.  However,  it  must  be  pointed  out  that 
the  environment  in  which  Monilipsolus  is  preserved  shows  no  evidence  of  strong  current  activity. 
Another  possibility  is  that  they  are  in  some  way  associated  with  defence,  possibly  openings  for 
extruding  some  form  of  sticky  substance  as  the  Cuverian  tubules  do.  However,  although  they  form 
a continuous  ring  around  the  periphery  of  the  animal,  which  gives  all  round  protection,  the 
openings  are  directed  slightly  downwards  and  one  might  expect  structures  associated  with  defensive 


66 


PALAEONTOLOGY,  VOLUME  34 


secretions  to  be  scattered  over  the  entire  dorsal  surface  rather  than  being  restricted  to  the  very 
periphery. 

The  most  likely  interpretation  is  that  these  structures  were  sensory  in  function,  for  example 
housing  long  tube-feet  that  formed  a sensory  frill  around  the  entire  margin  of  the  animal.  However, 
this  fails  to  explain  why  the  ossicles  themselves  are  so  massive  and  we  assume  that  tube-feet  were 
needed  to  provide  grip  and  on  the  ventral  surface  were  directed  downwards,  not  laterally. 

The  stout  perforate  ossicles  that  rim  this  species  are  highly  distinctive  and  should  be  recognizable 
even  from  disarticulated  debris.  Interestingly,  no  such  ossicles  have  ever  been  recorded  from  the  St 
Cassian  Beds  (Cassian,  late  Middle  Triassic)  of  the  Cortina  d'Ampezzo  district  of  Italy,  where  a very 
rich  echinoderm  fauna  has  been  documented  by  Zardini  (1976).  Zardini  has  carefully  identified  a 
large  number  of  isolated  skeletal  elements,  many  of  them  very  small,  including  echinoid  spines, 
asteroid  and  ophiuroid  ossicles,  crinoid  columnals  and  even  somphocrinid  cups.  The  absence  of 
monilipsolid  ossicles  in  the  St  Cassian  Beds  is  thus  unlikely  to  be  due  to  collection  failure. 


Monilipsolus  mirabilis  sp.  nov. 

Pate  4,  figs  1-3;  Plate  5,  figs  1-4;  Text-figs  7-14 
Diagnosis.  As  for  the  genus. 

Types.  Holotype  MGB  32385  (Text-fig.  7);  paratypes  MGB  30561,  30565,  30569,  30572,  30576,  30671,  30674, 
32319,  32325,  32367,  32384,  BMNH  E27542-3. 

Other  material  studied.  MGB  32365,  32369  (sectioned). 

Age  and  distribution.  Middle  Triassic,  Ladinian,  known  only  from  La  Pedrera  d’en  Rogent,  Collbato, 
Catalonia,  north-eastern  Spain. 

Description.  Body  flattened  in  profile  and  oval  in  outline  with  the  skeleton  differentiated  into  a lower  (ventral) 
sole  of  thin  imbricate  plates,  a marginal  band  of  stout  perforate  ossicles  arranged  into  two  irregular  rows 
anteriorly,  and  an  upper  domed  surface  of  thicker  imbricate  plates  some  of  which  are  perforated  for  tube  feet. 
Individuals  range  from  about  25  mm  long  by  8 mm  wide  to  55  mm  by  18  mm.  Anterior  and  posterior  end  are 
uniformly  rounded,  the  anterior  (PI.  5,  fig.  1)  being  generally  slightly  wider  than  the  posterior  (PI.  5,  fig.  3).  The 
body  is  usually  parallel-sided  but  tapers  slightly  in  the  posterior  third  (Text-figs  9 and  10). 

The  ventral  surface  is  composed  of  a series  of  thin,  imbricate  plates  that  are  laterally  elongate  (PI.  5,  figs  1, 
3.  4).  Plates  are  widest  down  the  median  part  of  the  sole  and  become  more  equant  in  outline  towards  the  edge 
(Text-fig.  1 3).  Very  rarely  one  or  more  of  the  sole  plates  around  the  margin  may  be  perforated  like  the  marginal 
ossicles  (Text-fig.  14).  The  ventral  plates  usually  have  a high  degree  of  overlap  and  imbricate  towards  the 
posterior.  None  of  the  ventral  plates  is  perforated  for  tube  feet  but  around  the  edge  of  this  surface,  immediately 
adjacent  to  the  stout  marginal  ossicles,  are  found  small  (0-3  mm)  gaps  that  in  places  appear  almost  circular. 
These  may  mark  the  sites  of  ventral  tube  feet.  Although  no  definite  remains  of  tube  feet  are  preserved,  vague 
tubular  structures  in  between  marginal  ossicles  (Text-fig.  14)  may  possibly  represent  tube  feet. 

Marginal  ossicles  are  shaped  like  the  beads  of  a necklace  and  are  slightly  tapered  distally  (PI.  4,  fig.  1).  In 
larger  individuals  these  ossicles  are  about  2-0-2-3  mm  in  length  and  1 1-1-2  mm  in  width.  Each  is  perforated  by 
a 0-5  mm  diameter  cylindrical  pore  that  expands  very  slightly  towards  the  interior.  The  ossicles  have  a smooth 
surface  and  form  a continuous  ring  to  the  margin  of  the  body  (Text-fig.  8).  They  are  irregularly  arranged  into 


EXPLANATION  OF  PLATE  5 

Figs  1-4.  Monilipsolus  mirabilis  gen.  et  sp.  nov.  1,  MGB  30674  (paratype),  ventral  surface,  anterior  to  top.  2, 
BMNH  E27543  (paratype),  juvenile,  dorsal  surface,  anterior  to  the  right  (see  also  Text-fig.  9).  3,  MGB  30576 
(paratype),  ventral  surface,  posterior  to  top  (see  also  Text-fig.  13).  4,  MGB  30561  (paratype),  ventral  surface, 
anterior  portion,  (see  also  Text-fig.  14).  All  x 4. 

All  specimens  from  the  Ladinian,  Middle  Triassic  at  La  Pedrera  d’en  Rogent,  Collbato,  north-eastern  Spain. 


PLATE  5 


SMITH  and  GALLEMI,  Monilipsolus 


68 


PALAEONTOLOGY,  VOLUME  34 


anterior 


ambulacral 
pores 


marginals 


1 mm 


marginals 


mouth 


text-fig.  1 1 . Monilipsolus  mirabilis 
gen.  et  sp.  nov.,  camera  lucida  drawing 
of  MGB  32367 ; paratype  (see  PL  4,  fig. 
1).  Anterior  portion  seen  in  dorsal 
aspect  showing  peristome  and  tube  foot 
pores. 


an  upper  and  lower  alternating  series,  but  this  becomes  better  defined  around  the  anterior  and  posterior 
borders  where  two  distinct  rows  of  marginals  are  present  (Text-fig.  1 1 ).  The  pores  on  marginal  ossicles  open 
distally  and  are  usually  just  visible  in  ventral  aspect  (PI.  5,  fig.  4)  but  not  in  dorsal  aspect  (PI.  4,  fig.  1). 

The  dorsal  surface  was  domed  in  life  but  is  now  usually  collapsed.  It  is  composed  of  imbricate  plates  that 
are  thicker  than  those  of  the  sole  (about  0- 1 5—0-2  mm  in  thickness)  and  show  a much  smaller  degree  of  overlap 
(Text-figs  II  and  12).  There  is  no  recognizable  organization  to  this  surface.  Both  the  mouth  and  anus  lie  on 
this  surface.  The  peristome  is  recognizable  as  a large  area  of  concentrically  arranged  platelets  around  a central 
hole  situated  close  to  the  anterior  (PI.  4,  figs  I and  3;  Text-figs  7-11).  Platelets  decrease  in  size  towards  the 
opening  and  there  are  no  larger  valve-like  plates  protecting  the  mouth.  The  peristome  occupies  most  of  the 
anterior  end  of  the  body.  The  anus  lies  near  the  posterior  end  of  the  body  and  in  some  specimens  appears  to 
form  a small  tail-like  projection  (Text-figs  9 and  10;  PI.  4,  fig.  3;  PI.  5,  fig.  2).  In  between  the  peristome  and 
anal  tail  many  of  the  dorsal  plates  are  perforated  for  tube  feet  (PI.  4,  fig.  2;  Text-figs  1 1 and  12).  These  pores 


SMITH  AND  GALLEM I:  MIDDLE  TRIASSIC  HOLOTHURIANS 


69 


text-fig.  12.  Monilipsolus  mirabilis 
gen.  et  sp.  nov.,  camera  lucida  drawing 
of  dorsal  plating  in  MGB  30671  (para- 
type)  showing  the  distribution  of  the 
tube  foot  pores  (see  PI.  4,  fig.  2). 


A 


are  more  or  less  scattered  over  the  entire  surface  with  a tendency  to  be  concentrated  into  two  bands,  one  on 
each  side  of  the  mid-line  (Text-fig.  12). 

The  complete  calcareous  ring  is  not  seen  in  any  specimen  but  elements  of  it  are  exposed  in  a slightly 
disaggregated  specimen,  MGB  30674.  The  interradial  elements  are  narrow  and  spade-shaped,  lacking  posterior 
processes  but  with  a large  anterior  projection.  The  radial  elements  are  broader  than  long  and  also  lack  posterior 
processes,  the  posterior  border  being  distinctly  concave.  There  is  a moderately  deep  anterior  notch  centrally 
which  in  effect  defines  two  small  anterior  processes.  This  notch  may  in  fact  become  closed  over  anteriorly  so 
as  to  form  a pore. 

Remarks.  Like  other  holothurians  from  this  locality,  specimens  of  this  species  commonly  display  a 
mid-ventral  groove  due  to  early  diagenetic  compaction  and  collapse  of  the  skeleton  above  the 
digestive  tract. 


70 


PALAEONTOLOGY,  VOLUME  34 


POSTERIOR 


?Pores 


text-fig,  13.  Monilipsolus  mirabilis  gen.  et  sp.  nov., 
camera  lucida  drawing  of  MGB  30576;  paratype  (see 
PI.  5,  fig.  3).  Ventral  surface  showing  sole  plating. 


Order  aspidochirotida  Grube,  1840 
Family  uncertain 
Genus  collbatothuria  nov. 

Derivation  of  name ; after  the  village  of  Collbato  near  where  the  species  was  found. 

Type  species.  Collbatothuria  danieli  sp.  nov. 

Age  and  distribution.  Middle  Triassic,  Ladinian,  known  only  from  La  Pedrera  d’en  Rogent,  Collbato, 
Catalonia,  north-eastern  Spain. 

Diagnosis.  Small  (up  to  50  mm  in  length),  vermiform,  differentiated  dorso-ventrally  into  a sole  with 
many  tube-feet  and  a latero-dorsal  surface  lacking  tube-feet  and  without  warts.  Mouth  large,  open, 
at  anterior  but  slightly  ventral.  Anus  at  posterior  terminus.  Body  wall  thick  and  heavily  calcified  but 
not  plated.  Form  of  body-wall  spiculation  unknown.  Calcareous  ring  present,  but  form  unknown; 
apparently  simple  without  anterior  projections. 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHU  RIANS 


71 


text-fig.  14.  Monilipsohis  mirabilis  gen.  et  sp. 
nov.,  camera  lucida  drawing  of  MGB  30561; 
paratype  (see  PI.  5,  fig.  4).  Ventral  surface 
showing  sole  plating  and  marginals. 


perforate 

plate 


? tube-foot 


marginals 


Remarks.  The  systematic  position  of  this  genus  remains  uncertain.  Its  thick  wrinkled  body  wall, 
obviously  heavily  calcified  with  spicules,  its  straight  cylindrical  body  and  differentiated  sole,  and 
simple  calcareous  ring  are  all  suggestive  of  Aspidochirotida.  Three  families  are  currently  recognized 
within  the  Aspidochirotida  (Pawson  1982),  but  unfortunately  they  are  differentiated  solely  on  soft 
tissue,  anatomical  structures  (arrangement  of  gonads,  presence/absence  of  tentacle  ampullae).  It  is 
therefore  impossible  to  be  more  specific  about  the  taxonomic  placement  of  Collbatothuria.  In 
general  body  form  and  organization  it  resembles  several  genera  within  the  Holothuriidae  and 
Stichopidae.  Collbatothuria  has  relatively  smooth  dorsal  and  lateral  surfaces  with  only 
circumferential  crenulations  associated  with  contraction.  Wart-like  projections  are  absent  from 
dorsal  and  lateral  surfaces  and  there  is  also  no  evidence  of  tube  feet  in  this  region,  though  they  are 
clearly  developed  over  the  sole.  These  characters  differentiate  Collbatothuria  from  extant  genera  of 
Holothuriidae  and  Stichopidae. 

The  well  differentiated  sole  with  its  numerous  tube  feet  indicate  that  Collbatothuria  was  an 
epifaunal  benthic  crawler  with  a locomotory  sole.  Its  downward-opening  mouth  suggests  that  it  was 
a deposit-feeder,  using  its  tentacles  to  pick  up  suitable  detritus  from  the  sea  floor.  Its  mode  of  life 
was,  therefore,  similar  to  that  of  modern  Holothuriidae  and  Stichopidae. 


Collbatothuria  danieli  sp.  nov. 

Plate  3,  fig.  4;  Text-figs  15-18 

Derivation  of  name ; in  honour  of  Dr  Daniel  Gutierrez,  an  amateur  palaeontologist  who  discovered  the 
holotype  and  other  specimens. 


Diagnosis.  As  for  the  genus. 


72 


PALAEONTOLOGY,  VOLUME  34 


B 

text-fig.  15.  Collbatothuria  danieli  gen.  et  sp.  nov.;  a,  dorsal  surface,  BMNH  E27544  (see  Text-fig.  17);  b, 
ventral  surface  of  holotype,  MGB  32273  (see  Text-fig.  16).  Both  specimens  x4. 


Types.  Holotype  MGB  32273;  paratypes  MGB  32274,  32377,  32383  (PI.  1,  fig.  1;  ‘C’),  BMNH  E27544. 

Age  and  distribution.  Middle  Triassic,  Ladinian,  known  only  from  La  Pedrera  d’en  Rogent,  Collbato, 
Catalonia,  north-eastern  Spain. 

Description.  Specimens,  which  are  sausage-shaped,  are  35  mm  to  52  mm  long.  They  were  presumably  ovoid  in 
cross-section,  but  are  now  flattened  due  to  diagenetic  compression  with  a median  furrow  marking  the  digestive 
tract  (Text-fig.  15).  Their  overall  shape  varies  with  the  state  of  contraction.  Contracted  specimens  are  rather 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHURIANS 


73 


text-fig.  16.  Collbatothuria  danieli  gen.  et  sp.  nov.,  camera  lucida 
drawing  of  MGB  32273  (holotype).  Ventral  surface. 


Tube  feet 


ANTERIOR 


Mouth 


calcareous 

ring 


Anu 


POSTERIOR 


5 mm 


short  and  fat,  with  a maximum  width  that  is  almost  50%  of  the  length  (PI.  1,  fig.  I ; lC’).  Others  are  more 
elongate  with  a width  that  is  only  about  20%  of  the  length  (PI.  3,  fig.  4).  One  specimen  is  preserved  in  a U- 
shaped  position  (Text-fig.  18),  but  other  specimens  are  all  straight. 

The  mouth  lies  anteriorly  facing  downwards  (Text-figs  1 5 and  1 6).  It  is  a large  circular  opening,  some  2-5  mm 
in  diameter  in  a 35  mm  long  specimen.  This  opening  is  surrounded  by  a ring-like  structure  of  individual 
elements  which  represents  the  calcareous  ring  (Text-fig.  16).  The  precise  structure  of  the  calcareous  ring  cannot, 
however,  be  made  out  since  it  is  covered  by  thick  integument.  There  appear  to  be  only  ten  elements  and  none 
has  strong  anterior  projections.  There  is  no  visible  body  wall  plating,  the  body  being  a wrinkled  integument 
(PI.  3,  fig.  4;  Text-fig.  15).  This  integument  is  relatively  thick  and  presumably  must  have  been  heavily  spiculated 
to  be  preserved,  but  the  silicification  has  destroyed  any  original  spicules  that  were  present.  The  dorsal  surface 
is  virtually  smooth  and  wrinkle-free  (Text-figs  15a  and  17)  and  has  no  papillae,  tube  feet  or  warty  projections. 
The  ventral  surface  is  generally  concave  and  presumably  contracted  prior  to  death.  It  is  differentiated  as  a sole 
and  there  are  numerous  small  tube  feet  on  this  surface  (Text-figs  15b,  16).  The  ventral  surface  is  much  more 
strongly  wrinkled  than  the  dorsal  surface  and  papillae  are  well  developed  along  the  margin  of  the  sole  (PI.  3, 
fig.  4;  Text-fig.  18).  The  anus  is  terminal  and  in  MGB  32273  is  marked  by  a concentric  valvular  appearance 
to  the  integument  (Text-figs  15b  and  16).  In  MGB  32274  there  appear  to  be  a few  larger  papillae  developed 
around  the  anus  (Text-fig.  18). 


EVOLUTIONARY  IMPLICATIONS  OL  THE  LAUNA 

The  Collbato  fossil  bed  is  uniquely  important  in  yielding  a fauna  of  holothurians  in  relative 


74 


PALAEONTOLOGY,  VOLUME  34 


ANTERIOR 


text-fig.  17.  Collbatothuria  danieli  gen.  et  sp.  nov.,  camera  lucida 
drawing  of  BMNH  E27544  (paratype).  Dorsal  surface:  cross- 
hatching  = sediment  covered  areas. 


abundance,  belonging  to  three  separate  families.  What  is  more,  these  are  by  far  the  best  preserved, 
complete  specimens  of  fossil  holothurians  that  have  ever  been  discovered.  Only  in  one  other  fossil 
holothurian  can  details  of  general  anatomical  arrangement,  body-wall  plating  and  the  structure  of 
the  calcareous  ring  be  documented  and  that  is  the  synaptid  apodan  Achistrum  from  the  Middle 
Pennsylvanian  of  Illinois.  The  information  available  on  these  species  makes  it  possible  to  place  them 
within  a biological  classification  established  on  Recent  species  with  a fair  degree  of  certainty. 

Two  other  species,  Oneirophantites  tarragonensis  Cherbonnier  and  Bathysynactites  viai 
Cherbonnier,  have  been  reported  from  the  Middle  Triassic  of  Tarragona,  Spain  (Cherbonnier 
1978).  Neither  is  well  preserved  or  reveals  as  much  anatomical  information  as  the  three  species 
described  here,  since  they  are  preserved  only  as  decalcified  impressions.  However,  Oneirophantites 
was  tentatively  assigned  to  the  order  Elasipoda  on  account  of  its  long  lateral  papillae  and  the 
position  of  the  mouth,  and  Bathysynactites  was  assigned  to  the  Aspidochirotida.  Both  were 
preserved  in  anoxic  facies  of  Middle  Triassic  (Muschelkalk)  age. 

Taking  the  Tarragona  and  Collbato  fossil  holothurians  together,  gives  a Middle  Triassic  fauna 
of  five  species.  These  belong  to  three  orders,  namely  Elasipodida,  Aspidochirotida  and 
Dendrochirotida.  Members  of  a fourth  order,  Apodida,  must  have  been  present  since  the  group  had 
already  differentiated  by  the  Upper  Carboniferous,  as  shown  by  the  Achistrum  sp.  from  the  Mazon 
Creek  Shale.  Thus,  of  the  six  extant  orders  of  Holothurioida,  only  Molpadiida  and  Dactylochirotida 
have  no  fossil  record  by  the  early  Mesozoic.  Considerable  taxonomic  diversity  of  holothurians  had 
therefore  been  achieved  by  the  Middle  Triassic.  Furthermore,  a certain  amount  of  ecological 


SMITH  AND  GALLEMI:  MIDDLE  TRIASSIC  HOLOTHU  RIANS 


75 


ANTERIOR 


POSTERIOR 


text-fig.  18.  Collbatothuria  danieli  gen.  et  sp.  nov.,  camera  lucida  drawing  of  MGB  32274;  paratype  (see  PI. 
3,  fig.  4).  Specimen  in  lateral  view  with  ventral  surface  towards  the  interior. 


diversification  is  also  evident.  In  the  Middle  Triassic  we  can  recognize  epibenthic,  deposit-feeding 
forms  with  well  developed  soles  ( Collbatothuria , IBathysynactites,  lOneirophantites ),  burrowers 
( Strobilothyone ) and  epibenthic,  psolid-like  suspension-feeders  that  attached  to  firm  bottoms 
(Monilipso/us).  Considering  how  well  skeletized  some  of  these  taxa  are  and  how  diverse  holothurians 
had  become  by  the  Middle  Triassic,  it  is  surprising  to  us  how  rarely  they  have  been  reported  in  the 
fossil  record. 


Acknowledgements.  Field  trips  have  been  covered  with  funds  of  the  MGB’s  Project  'Work  on  fossiliferous 
localities’  (1988  and  1989)  financed  by  the  Ajuntament  de  Barcelona  (Area  de  Cultura-Secretaria  Technica  de 
Museus).  A British  Council’s  Academic  Travel  Grant  allowed  one  of  us  (J.G.)  to  carry  out  research  for  the 
paper.  We  thank  also  D.  Brusi  for  presenting  the  first  material  from  Collbato,  Dr  J.  M.  Pons,  E.  Vicens  and 
J.  Munoz  (Universitat  Autonoma  de  Barcelona)  for  their  help  in  previous  phases  of  the  study,  Mr  E.  Rogent 
for  allowing  us  access  to  his  quarry  and  D.  Gutierrez,  R.  Mane  and  I.  Gurrea  for  donating  important 
specimens.  Dave  Pawson,  Chris  Paul  and  Paul  Gilliland  provided  helpful  comments  on  an  earlier  draft  of  the 
paper,  for  which  we  are  grateful. 


76 


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calvet,  f.,  march,  m.  and  pedrosa,  a.  1987.  Estratigrafia,  sedimentologia  y diagenesis  del  Muschelkalk 
superior  de  los  Catalanides.  Cuadernos  Geologia  Iberica , 11,  171-197. 

— and  tucker,  M.  E.  1988.  Outer  ramp  cycles  in  the  Upper  Muschelkalk  of  the  Catalan  Basin,  northeast 
Spain.  Sedimentary  Geology , 57,  185-198. 

calzada,  s.  and  Gutierrez,  d.  1988.  Ofiuras  (Echinodermata)  del  Ladiniense  Catalan.  Batalleria , 1,  31-38. 
cherbonnier,  g.  1978.  Note  sur  deux  empreintes  d'holothuries  fossiles  du  Trias  moyen  de  la  region  de 
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deflandrf.-rigaud,  M.  1962.  Contribution  a la  connaissance  des  sclerites  d’holothurides  fossiles.  Memoires  du 
Museum  d'Histoire  naturelle  de  Paris,  11,  1-123. 

frizzel,  D.  l.  and  exline,  H.  1955.  Monograph  of  fossil  holothurian  sclerites.  Missouri  University  School  of 
Mines  and  Metallurgy  Bulletin,  Technical  Series,  89,  1-204. 

1966.  Holothuroidea  - fossil  record.  U646-672.  In  moore,  r.  c.  (ed. ).  Treatise  on  invertebrate 
paleontology.  Part  U.  Echinodermata  3.  Geological  Society  of  America  and  University  of  Kansas  Press, 
Boulder,  Colorado  and  Lawrence,  Kansas,  695,  pp. 

gatlemi,  j.  1990.  Nuevos  equinodermos  del  Muschelkalk  superior  (Ladiniense)  de  Cataluna.  In  civis,  J.  and 
flores,  J.  a.  (eds),  Actas  de  Paleontologia  (Actas  de  las  IV  Jornadas  de  Paleontologia,  Salamanca  1988); 
Acta  Salmanticensia,  Bibliotheca  de  las  Ciencias  68,  141-147. 
grube,  a.  E.  1840.  Actinien , Echinodermen  und  Warmer  des  Adriatischen  und  Mittelmeers.  J.  H.  Bon,  Konigsberg, 
92  pp.,  1 pi. 

hess,  h.  1973.  Neue  Echinodermen-Funde  aus  dem  mitteleren  Dogger  des  Aargauer  Juras.  Eclogae  geologicae 
Helvetica.  66.  625-656. 

jekelius,  e.  1936.  Der  Weisse  Triaskalk  von  Brasov  und  seine  Fauna.  Amdand  Institutului  Geologic  al  Romaniei, 


masachs,  v.  1981.  Itinerari  M2-C.  Manresa-Monistrol  de  Montserrat-Collbato.  70-72.  In  masachs,  v.  (ed.). 
Itineraris  Geologies.  Bages,  Bergueda,  Anoia,  Solsones.  Centre  d’Estudis  Geologies  ‘Valenti  Masachs’, 
Manresa,  103  pp. 

mihaly,  s.  1981.  Az  Aggteleki-Karszt  kozepso-Triasz  Echinoidei.  Magyar  Allami  Foldtani  IntezevEvi  Jelentese, 
(1979),  297-331. 

pawson,  d.  l.  1970.  The  marine  fauna  of  New  Zealand:  sea  cucumbers  (Echinodermata:  Holothuroidea).  New 
Zealand  Department  of  Scientific  and  Industrial  Research,  Bulletin,  201.  7-69. 

- 1982.  Holothuroidea.  791-818.  In  Parker,  s.  p.  (ed.).  Synopsis  and  classification  of  living  organisms, 
vol.  2.  McGraw-Hill,  New  York,  1232  pp. 

perrier,  R.  1902.  Holothuries,  in  Expedition  seientifique  de  la  Travailleur  et  du  Talisman.  G.  masson,  Paris, 
273-554  pp„  pis  12-22. 

ROSELL,  J.,  TRILLA,  J.,  OBRADOR,  A.,  PEON,  A.,  ALONSO,  F.,  RAMIREZ,  J.  and  CABANAS,  J.  1975.  Mapa  Geoldgico 
de  Espana.  E.  1 : 50,000.  Sabadell  (392).  Instituto  Geoldgico  y Minero  de  Espaha,  31  pp.,  1 folded  map. 

seibertz,  e.  1988.  Symposium  report : ler  Congreso  Nacional  de  Paleontologia,  Mexico  City,  16-20  November 
1987.  Cretaceous  Research,  9,  391  only. 

seilacher.  a.  1961.  Holothurien  im  Hunsriickschiefer  (Unter-Devon).  Notizblatt  des  Hessischen  Landesamtes 
fiir  Bodenforschung  zu  Wiesbaden,  89,  66-72. 

smith,  a.  b.  1990.  Echinoid  evolution  from  the  Triassic  to  the  Lower  Jurassic.  Cahiers  de  I’lnstitut  Catholique 
de  Lyon,  series  Science  3,  79-1 17. 

sroka,  s.  D.  1988.  Preliminary  studies  on  a complete  fossil  holothurian  from  the  Middle  Pennsylvanian  Francis 
Creek  Shale  of  Illinois.  159-160.  In  burke,  r.d.,  mladenov,  p.  v.,  Lambert,  p.  and  parsley,  r.  l.  (eds). 
Echinoderm  Biology.  A. A,  Balkema,  Rotterdam,  818  pp. 

zardini.  r.  1976.  Fossili  di  Cortina : Atlante  degli  Echinodermi  Cassiani  Trias  Medio  superiore  della  regione 
Dolomitica  attorno  a Cortina  d Ampezzo.  Foto  Ghedina,  Lugglio,  29  pp.,  22  pis. 


17,  1-106. 


ANDREW  B.  SMITH 

Department  of  Palaeontology 
British  Museum  (Natural  History) 
Cromwell  Road,  London  SW7  5BD 


Typescript  received  25  October  1989 
Revised  typescript  received  8 January  1990 


Jaume  gallemi 

Museu  de  Geologia 
Parc  de  la  Ciutadella  s/n 
08003  Barcelona,  Spain 


A NEW  UPPER  ORDOVICIAN  BRYOZOAN  FAUNA 
FROM  THE  SLADE  AND  REDHILL  BEDS,  SOUTH 

WALES 

by  CAROLINE  J.  BUTTLER 


Abstract.  A diverse  bryozoan  fauna  has  been  discovered  in  South  Wales  in  the  Slade  and  Redhill  Beds  (upper 
Rawtheyan,  Ashgill),  exposed  in  a new  road-cutting  near  Whitland.  This  is  the  first  account  of  a moderately 
diverse  Ordovician  bryozoan  fauna  from  Britain.  The  fauna  is  represented  by  15  species  belonging  to  four 
orders,  the  majority  being  Trepostonrata.  One  new  genus  is  described,  Pinnatoporella  (Fenestrata),  and  three 
new  species  Heterotrypa  sladei , Dekayia  pengawsensis , and  Anaphragma  gwyndyense  (all  Trepostomata).  New 
information  has  led  to  the  redescription  of  the  cystoporate  family  Rhinoporidae  and  its  reassignment  to  the 
suborder  Ceramoporina.  Ordovician  bryozoans  are  poorly  known  in  Britain,  partly  because  well-preserved 
diverse  faunas  such  as  this  are  very  rare.  The  fauna  is  compared  biogeographically  with  previously  described 
Bryozoa.  At  generic  level  it  is  cosmopolitan;  however,  approximately  half  the  species  are  endemic  to  Wales. 
The  remaining  species  have  greatest  affinity  with  Baltoscandia ; species  level  affinities  with  North  America  are 
poorer. 

Bryozoans  are  one  of  the  major  components  of  Ordovician  faunas.  They  have  been  described 
extensively  from  North  America  and  the  Soviet  Union  but  have  been  largely  neglected  in  Britain. 
This  neglect  may  be  attributed  partly  to  poor  preservation  and  the  time  required  to  prepare 
specimens,  but  it  is  also  due  to  the  lack  of  any  great  tradition  of  research  on  British  Palaeozoic 
bryozoans.  No  entire  bryozoan  fauna  has  previously  been  described  from  a British  upper 
Ordovician  locality.  Worldwide  biogeographical  comparisons  of  Ordovician  bryozoans  therefore 
omit  Britain. 


PREVIOUS  RESEARCH  ON  BRITISH  ORDOVICIAN  BRYOZOANS 

Bryozoans  are  frequently  decalcified  in  British  Ordovician  rocks,  making  them  easy  to  distinguish 
in  the  field  but  hard  to  identify  taxonomically  even  to  family  level.  In  faunal  community  studies 
bryozoans  are  often  only  identified  by  their  gross  morphology,  for  example  'stick  bryozoans’  or 
'prasoporid’,  the  latter  term  covering  any  dome-shaped  trepostome.  Calcified  specimens  tend  to  go 
unnoticed  in  the  field,  except  in  a few  localities  such  as  the  Slade  and  Redhill  Beds  at  Pengawse  Hill 
in  South  Wales,  described  herein,  where  a large  proportion  of  the  rock  consists  of  bryozoans. 

In  major  British  museums  (e.g.  Natural  History  Museum,  London;  Sedgwick  Museum, 
Cambridge)  there  are  numerous  decalcified  bryozoans,  typically  fenestrates,  collected  from  North 
Wales.  Locality  information  is  often  minimal,  for  example  'Bala  Beds’.  Many  of  these  specimens 
were  collected  early  this  century  and  the  material  is  often  of  little  palaeontological  value. 

Ordovician  bryozoans  from  Britain  were  first  examined  in  the  mid-nineteenth  century  when  they 
were  identified  as  corals  (e.g.  M’Coy  1850;  Milne-Edwards  and  Haime  1854).  Many  of  these  early 
descriptions  are  scanty,  with  poor  illustrations,  often  showing  no  internal  morphology.  Nicholson 
and  Etheridge  (1877)  and  Nicholson  (1879)  began  to  include  detailed  diagrams  of  sections  of 
specimens  showing  internal  features. 

No  major  monographic  study  of  British  Ordovician  bryozoans  has  been  completed  and  only  a 
few  papers  dealing  with  small  aspects  of  the  fauna  have  been  published.  Spjeldnaes  (1957)  re- 


(Palaeontology,  Vol.  34,  Part  1,  1991,  pp.  77-108.  7 pls.| 


© The  Palaeontological  Association 


78 


PALAEONTOLOGY,  VOLUME  34 


described  some  type  specimens  of  British  species  and  later  examined  some  silicified  specimens  from 
the  Llandeilo  of  South  Wales  (Spjeldnaes  1963). 

Ross,  in  three  papers  (1962,  1963,  1965),  examined  some  of  the  Caradoc  (Cautleyan)  bryozoans 
of  Shropshire.  This  is  the  most  extensive  study  of  an  Ordovician  bryozoan  fauna  from  Britain  to 
date.  Eight  species  were  described  from  three  localities.  The  fauna  includes  seven  trepostomes  and 
one  cryptostome. 

There  are  a few  papers  describing  just  one  Ordovician  species  or  genus  (e.g.  Etheridge  1879; 
Shrubsole  1885).  The  latest  of  these  is  by  Taylor  and  Cope  (1987),  who  describe  a specimen  of  the 
trepostome  genus  Orbipora  from  the  Lower  Arenig  of  South  Wales,  noteworthy  because  it  is  the 
oldest  bryozoan  described  in  the  literature. 

Virtually  no  palaeoecological  work  has  been  done  on  British  Ordovician  bryozoans.  One 
exception  is  a study  by  McNamara  (1978)  on  the  symbiosis  between  gastropods  and  trepostomes 
in  the  Coniston  Limestone  Group  of  Cumbria.  Detailed  systematic  descriptions  are  essential  before 
more  interpretive  studies  can  be  undertaken  on  the  British  fauna. 


KEY 

SLADE  AND  REDHILL  BEDS 
SHOLESHOOK  LIMESTONE 
DICRANOGRAPTUS  SHALES 


text-fig.  1.  Map  showing  the  bryozoan  locality  in  the  Slade  and  Redhill  Beds  near  Whitland,  Dyfed. 


MATERIAL 

All  study  material  was  collected  recently  from  the  Slade  and  Redhill  Beds  (upper  Rawtheyan, 
Ashgill),  west  of  Whitland,  Dyfed  (National  Grid  Reference  SN  164170).  The  outcrop  is  a long  road 
section  (800  m),  revealed  during  the  construction  of  a new  route  for  the  A40  trunk  road  at  Pengawse 
Hill,  exposing  horizons  from  the  Dicranograptus  Shales  (Caradoc)  in  the  east,  through  the 
Sholeshook  Limestone  (lower  Ashgill),  to  the  Slade  and  Redhill  Beds  in  the  west  (Text-fig.  1).  The 
majority  of  bryozoans  were  confined  to  a 0-3  m thick  band  composed  almost  entirely  of  trepostome 
bryozoans  in  a matrix  of  argillaceous  limestone.  Crinoid  fragments,  trilobites  (e.g.  Stenopareia  sp. 
and  Tretaspis  sp.),  bivalves,  cephalopods  and  brachiopods  (e.g.  Leptaena  sp.)  were  also  found. 

The  majority  of  specimens  examined  from  Pengawse  Hill  were  calcified,  although  many  of  the 
bryozoans  at  or  near  the  surface  of  the  outcrop  were  partially  or  totally  decalcified.  Silicification  is 
seen  to  occur  in  some  of  the  calcified  colonies.  This  process  can  destroy  the  microstructure,  but  in 
the  majority  of  affected  colonies  the  silicification  is  not  too  advanced.  In  tangential  sections  of  some 
colonies  a clear  ring  of  silica  can  be  seen  around  the  zooecial  apertures,  replacing  the  bryozoan 
calcite  which  forms  the  zooecial  linings  (PI.  3,  fig.  7). 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


79 


The  bryozoan  fauna  at  Pengawse  Hill  is  very  diverse  by  British  standards.  A total  of  fifteen 
species  has  been  identified,  three  of  which  are  new.  Four  orders  are  represented:  Trepostomata, 
Cystoporata,  Fenestrata  and  Cyclostomata.  Trepostomes  dominate  with  ten  species.  Fourteen 
bryozoan  species  are  described  in  detail  in  the  present  work;  the  cyclostome  Kukersella  borealis 
(Bassler)  is  described  fully  elsewhere  (Buttler  1989)  and  only  a brief  description  is  given  here. 


SYSTEMATIC  PALAEONTOLOGY 

The  terminology  used  in  all  descriptions  is  that  of  Boardman  et  al.  (1983).  All  genera  are  placed  in  families 
based  on  the  following  sources:  trepostomes  - Astrova  (1978);  cystoporates  - Utgaard  (in  Boardman  et  al. 
1983);  and  phylloporinids  - Lavrentjeva  (1985).  Classification  of  Palaeozoic  trepostome  and  fenestrate 
bryozoans  at  family  level  is  generally  unsatisfactory  and  is  currently  being  revised  for  the  Treatise  on 
invertebrate  paleontology. 

Not  all  taxa  can  be  identified  to  species  level  due  to  poor  preservation  or  lack  of  material.  In  these  cases, 
the  species  are  left  in  open  nomenclature  and  are  referred  to  as  ‘cf.  ’ or  ‘sp.  as  recommended  by  Bengtson 
(1988). 

Biometric  details  for  each  trepostome  species  are  tabulated  (Table  1).  Each  measurement  was  made  up  to 
seven  times  per  specimen.  The  range  and  mean  are  calculated  for  each  parameter.  All  the  raw  data  and  further 
statistical  details  can  be  found  in  an  unpublished  Ph.D.  thesis  (Buttler  1988).  All  specimens  described  are  thin 
sections/acetate  peels  unless  otherwise  stated. 

Repository  abbreviations:  BMNH,  Natural  History  Museum,  London;  SM,  Sedgwick  Museum, 
Cambridge;  BGS,  British  Geological  Survey,  Keyworth;  NMW,  National  Museum  of  Wales,  Cardiff. 

Phylum  bryozoa  Ehrenberg,  1831 
Class  stenolaemata  Borg,  1926 
Order  trepostomata  Ulrich,  1882 
Suborder  halloporoidea  Astrova,  1965 
Family  heterotrypidae  Ulrich,  1890 
Genus  heterotrypa  Nicholson,  1879 

Heterotrypa  s/adei  sp.  nov. 

Plate  1,  figs  1-5;  Text-fig.  2a 

Holotype.  BMNH  PD8167,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Paratypes.  BMNH  PD8 168-70,  from  the  same  horizon  and  locality  as  holotype. 

Etymology.  The  species  is  named  after  the  type  horizon. 

Diagnosis.  Colony  ramose.  Zooecia  parallel  branch  axis  in  endozone,  curving  gradually  outwards 
in  exozone.  Endozonal  walls  thin  and  slightly  wavy.  Autozooecia  rounded-polygonal  in  transverse 
section;  rounded,  occasionally  very  slightly  petaloid  in  shallow  tangential  sections.  Polygonal 
mesozooecia  present,  originating  throughout  colony.  Diaphragms  present  along  entire  length  of 
autozooecia,  common  in  exozone;  very  abundant  in  mesozooecia,  constricting  walls  and  producing 
a slightly  beaded  appearance.  Acanthostyles  small  and  common  throughout  colony. 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  7-5  mm  in  diameter.  Autozooecia  are  parallel 
to  branch  axis  in  the  inner  endozone  and  gradually  curve  outwards  to  meet  the  zoarial  surface  at  90°.  The 
autozooecia  within  the  endozone  have  thin,  slightly  wavy  walls.  The  exozone  has  an  average  diameter  of 
1 -26  mm,  and  is  recognized  by  a slight  thickening  of  the  zooecial  walls.  Autozooecia  all  originate  in  the  endozone 
where  they  are  rounded-polygonal  in  transverse  section.  They  become  rounded  and  occasionally  slightly 
petaloid  in  the  exozone,  as  seen  in  tangential  sections  of  branches.  Autozooecial  diameters  average  0-23  mm 
by  027  mm  in  the  exozone.  Thin,  orally  deflected  basal  diaphragms  are  found  along  the  entire  length  of  the 


80 


PALAEONTOLOGY,  VOLUME  34 


colony,  spaced  0 32  mm  apart  in  the  endozone  and  becoming  more  abundant  in  the  exozone  where  they  are 
spaced  013  mm  apart.  In  the  outer  endozone  and  exozone  occasional  cystiphragms  are  found. 

Mesozooecia  are  present  and  originate  throughout  the  colony.  In  the  endozone  they  are  polygonal  in 
transverse  section  and  become  polygonal-rounded  in  the  exozone,  as  seen  in  shallow  tangential  sections.  The 
maximum  diameter  of  the  mesozooecia  averages  O il  mm  in  the  exozone.  They  contain  abundant  orally 
deflected  diaphragms,  spaced  on  average  0T8  mm  apart  in  the  endozone  and  01  mm  apart  in  the  exozone. 
Mesozooecial  walls  are  sometimes  constricted  at  the  position  of  the  diaphragms,  producing  a slightly  beaded 
appearance. 

Acanthostyles  are  common  and  are  small  with  an  average  diameter  of  0-04  mm  and  density  of  9 mm-2.  They 
originate  throughout  the  colony,  some  are  confined  to  the  autozooecial  walls  but  others  indent  the  zooecial 
apertures,  producing  a slight  petaloid  effect.  The  acanthostyles  are  composed  of  a hyaline  core  surrounded  by 
steeply  dipping  laminae. 

Autozooecial  walls  are  thin  and  average  04  mm  in  thickness  in  the  exozone.  Wall  microstructure  is 
composed  of  steeply  inclined,  U-shaped  laminae.  The  zooecial  wall  boundaries  are  granular  and  indistinct. 

In  one  specimen  (PD8169)  there  is  a layer  of  thick  exozonal  type  wall  within  the  middle  endozone.  This  type 
of  feature  has  been  regarded  as  evidence  of  an  abandoned  growing  tip  (Boardman  1960). 

Remarks.  This  is  the  first  species  of  Heterotrypa  described  from  Great  Britain.  Heterotrypa  sladei 
sp.  nov.  is  characterized  by  very  abundant  diaphragms  throughout  the  zoarium,  beaded 
mesozooecia,  thin  endozonal  walls  and  small  acanthostyles  common  throughout  the  colony.  It  is 
unusual  for  the  genus  in  having  abundant  diaphragms  within  the  endozone.  Boardman  and  Utgaard 
( 1966,  p.  1 105)  in  their  revision  of  Heterotrypa  state  that  diaphragms  within  the  endozone  are  rare 
to  moderately  abundant. 

H.  sladei  is  similar  to  H . frondosa  (d'Orbigny,  1850)  illustrated  by  Boardman  and  Utgaard  (1966, 
pi.  140),  although  diaphragms  are  more  abundant  in  the  endozone  of  the  new  species.  H.  magnopora 
Boulange,  1963  was  described  from  the  Montagne  Noire  (upper  Ordovician)  and  has  a similar 
exozone  to  H.  sladei  but  differs  in  having  sparse  acanthostyles  in  the  endozone. 


Genus  dekayia  Milne- Edwards  and  Haime,  1851 
Dekavia  pengawsensis  sp.  nov. 

Plate  1,  figs  6-8;  Plate  2,  fig.  1 ; Text-fig.  2b. 

Holotype.  BMNH  PD8176,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Paratypes.  BMNH  PD8 178-9,  from  the  same  horizon  and  locality  as  holotype. 

Etymology.  The  species  is  named  after  the  type  locality. 


EXPLANATION  OF  PLATE  1 

Figs  1-5.  Heterotrypa  sladei  sp.  nov.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD8167  (paratype),  longitudinal  section,  x 15.  2,  BMNH 
PD8167  (holotype),  longitudinal  section,  x28.  3,  BMNH  PD8170  (paratype),  longitudinal  section,  showing 
layer  of  thicker  exozonal  material  within  the  endozone,  x48.  4,  BMNH  PD8169  (paratype),  tangential 
section,  x48.  5,  BMNH  PD8169  (paratype),  tangential  section,  showing  an  acanthostyle  inflecting  an 
autozooecium,  x 120. 

Figs  6-8.  Dekayia  pengawsensis  sp.  nov.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse 
Hill  diversion,  west  of  Whitland,  Dyfed.  6,  BMNH  PD8179  (paratype),  longitudinal  section,  x 15.  7,  BMNH 
PD8179  (paratype),  longitudinal  section,  showing  large  acanthostyles  in  endozone,  x 28.  8,  BMNH  PD8176 
(holotype),  tangential  section,  x48. 


PLATE  1 


BUTTLER,  Heterotrypa,  Dekayia 


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PALAEONTOLOGY,  VOLUME  34 


Diagnosis.  Colony  hemispherical.  Zooecia  originate  from  the  basal  lamina.  Zooecial  walls  wavy, 
slightly  thickened  in  exozone.  Autozooecia  polygonal  to  polygonal-rounded  in  transverse  section 
throughout  colony.  Polygonal  mesozooecia  uncommon.  Diaphragms  present  in  all  zooecia. 
Acanthostyles  abundant  throughout  colony. 

Description.  Zoaria  are  hemispherical  with  an  average  diameter  of  1 1 mm.  Autozooecia  all  originate  at  the 
centre  of  the  colony  and  curve  outwards  towards  the  zoarial  surface.  Autozooecial  walls  are  slightly  wavy 
throughout  the  colony.  Endozone:  exozone  boundary  indistinct.  Autozooecia  are  large,  with  an  average 
diameter  of  0-29  mm  by  0-32  mm,  and  are  polygonal  to  polygonal-rounded  in  transverse  section  throughout 
the  colony.  Thin  diaphragms  are  present,  though  not  abundant,  in  all  zooecia,  and  are  spaced  between 
0- 1 3 mm  and  0 86  mm  apart,  with  an  average  of  0-48  mm.  They  increase  in  frequency  slightly  at  the  periphery  of 
the  colony.  These  basal  diaphragms  are  all  deflected  orally  at  their  junctions  with  the  zooecial  walls  and  their 
laminae  are  continuous  with  the  autozooecial  linings. 

Mesozooecia  are  present  but  not  common.  They  are  polygonal  in  transverse  section  and  have  an  average 
maximum  diameter  of  0.12  mm.  Mesozooecia  contain  orally  deflected  basal  diaphragms,  spaced  on  average 
0T  1 mm  apart  in  the  exozone. 

Acanthostyles  are  abundant  and  originate  throughout  the  colony.  They  are  composed  of  a large  hyaline  core 
surrounded  by  steeply  dipping  laminae. 

Autozooecial  wall  thickness  averages  0 02  mm  in  the  exozone.  Wall  microstructure  is  composed  of  inclined 
U-shaped  laminae.  Zooecial  boundaries  are  distinguished  by  a darker  granular  zone  in  the  centre  of  the  walls. 

In  one  specimen  (PD8176)  hollow  ‘cyst’  structures  are  found  within  the  autozooecia.  These  are  spherical, 
average  003  mm  in  diameter,  and  occur  singularly  or  in  pairs.  The  ‘cysts’  are  attached  to  the  sides  of  the 
zooecial  walls  and  their  laminae  are  continuous  with  the  zooecial  linings. 

Two  of  the  specimens  (PD8176,  8178)  use  colonies  of  Leioclema  orbicularis  as  substrata  for  encrustation.  In 
all  of  the  colonies,  periods  of  growth  cessation  can  be  inferred  by  the  presence  of  a row  of  thick  basal 
diaphragms  followed  by  a change  in  the  orientation  of  the  zooecia. 

Remarks.  Dekayia  pengawsensis  sp.  nov.  is  primarily  characterized  by  the  hemispherical  form,  the 
thin  wavy  zooecial  walls  and  the  rare  mesozooecia.  Diaphragms  are  present  and  acanthostyles  are 
abundant  throughout  the  colony.  Prior  to  this  study  the  genus  Dekayia  had  not  been  recorded  in 
Britain. 

D.  pengawsensis  is  similar  internally  to  the  ramose  D.  aspera  Milne-Edwards  and  Haime,  1851, 
which  was  well  illustrated  by  Boardman  and  Utgaard  (1966,  pi.  138).  The  Welsh  specimens, 
however,  have  smaller  acanthostyles  and  more  abundant  diaphragms.  D.  semipilans  (Ulrich,  1890), 
figured  by  Brown  and  Daly  (1986,  pi.  4,  figs  9-12),  has  a similar  wall  structure  and  acanthostyles 
to  D.  pengawsensis  but  again  lacks  diaphragms.  D cf.  crenulata  Prantl,  1940  has  been  found  from 
the  same  locality.  This  differs  from  D.  pengawsensis  by  the  ramose  colony  form,  the  beaded 
mesozooecia  and  the  greater  abundance  of  acanthostyles. 


text-fig.  2.  Longitudinal  sketch  sections  of  new  species  of  bryozoans  described  from  the  Slade  and  Redhill 
Beds.  A,  Heterotrypa  sladei.  B,  Dekayia  pengawsensis.  C,  Anaphragma  gwyndyense. 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


83 


Dekayia  cf.  crenulata  Prantl,  1940 
Plate  2,  figs  2-4 

Material.  BMNH  PD8171-3,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  W of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  7 mm  in  diameter.  The  surfaces  of  all  specimens 
are  slightly  abraded.  Autozooecia  are  generally  parallel  to  the  branch  axis  in  the  endozone  and  they  gradually 
curve  outwards  and  meet  the  zoarial  surface  at  90°.  The  autozooecia  within  the  endozone  have  quite  thin 
crenulated  walls.  The  exozone  is  relatively  narrow  with  an  average  diameter  of  0 06  mm.  It  is  recognized  by 
a slight  thickening  of  the  zooecial  walls  and  a change  in  the  zooecial  orientation,  which  occur  simultaneously. 
Autozooecia  all  originate  in  the  endozone  where  they  are  polygonal-rounded  in  transverse  section.  They 
become  rounded  in  the  exozone  as  seen  in  tangential  sections  of  branches.  Autozooecial  diameters  average 
0-22  mm  by  0 27  mm.  Diaphragms  are  absent  in  the  endozone  but  are  occasionally  present  within  the  auto- 
zooecia in  the  exozone  where  they  are  spaced  on  average  0-25  mm  apart.  These  diaphragms  are  all  deflected 
orally  at  their  junctions  with  the  zooecial  walls  and  their  laminae  are  continuous  within  the  autozooecial 
linings. 

Mesozooecia  are  present  but  uncommon,  and  originate  in  the  outer  parts  of  the  endozone  and  inner  parts 
of  the  exozone.  They  are  rounded-polygonal  in  shape,  as  seen  in  shallow  tangential  sections,  and  have  a 
maximum  diameter  of  012  mm.  The  mesozooecia  contain  orally  deflected  basal  diaphragms,  spaced  on 
average  0-15  mm  apart  in  the  endozone  and  013  mm  in  the  exozone.  Mesozooecial  walls  often  have  a beaded 
appearance  in  longitudinal  section.  In  the  exozone  this  is  caused  by  the  zooecial  walls  constricting  slightly  at 
the  position  of  the  diaphragms.  In  the  endozone  the  mesozooecial  walls  appear  to  pinch  together,  producing 
a similar  beaded  appearance. 

Acanthostyles  are  very  abundant,  with  an  average  diameter  of  0 05  mm  and  density  of  7 mirr2  the  exozone. 
They  are  large  and  long,  originate  randomly  throughout  the  colony,  and  may  indent  autozooecial  walls. 
Acanthostyles  all  have  a wide  hyaline  core,  surrounded  by  steeply  dipping  conical  laminae. 

Autozooecial  wall  thickness  averages  0 03  mm  in  the  exozone.  Wall  microstructure  is  composed  of  inclined, 
U-shaped  laminae,  with  indistinct  zooecial  boundaries.  Some  zooecia  are  infilled  with  laminar  calcite  close  to 
the  colony  surface.  In  longitudinal  section  this  infilling  consists  of  very  broad  U-shaped  laminae. 

Remarks.  The  specimens  described  herein  are  distinguished  by  the  thin  crenulated  walls  in  the 
endozone,  the  rare  mesozooecia  and  the  large  abundant  acanthostyles  throughout  the  colony. 

Prantl  (1940)  described  the  Ashgillian  species  Dekayia  crenulata  from  east  of  Grange  du  Pin, 
Herault,  Montagne  Noire,  France.  This  species  has  slender  branches,  an  absence  of  mesozooecia, 
crenulated  autozooecial  walls  in  the  axial  region  of  the  zoarium  and  numerous  acanthostyles 
throughout  the  colony.  The  walls  and  acanthostyles  are  similar  in  specimens  from  Wales  and  the 
Montagne  Noire.  The  autozooecial  apertures  of  D.  crenulata  described  by  Prantl  are  generally 
smaller  than  those  of  the  specimens  from  Wales  (01 7—0-2 1 mm  Montagne  Noire;  0T 9-0-32  mm 
Wales);  however,  the  ranges  overlap.  The  size  of  the  colonies  also  varies:  D.  crenulata  has  a branch 
diameter  of  3-6^4-6  mm,  the  Welsh  specimens  are  larger  at  7-8  mm.  Mesozooecia  are  stated  as 
absent  in  D.  crenulata  by  Prantl.  In  the  Welsh  specimen  PD  8173  they  are  present  but  they  are  very 
rare  in  specimen  PD  8172.  This  may  reflect  within  species  variability.  For  the  present,  until  further 
material  can  be  examined,  the  specimens  are  assigned  to  D.  cf.  crenulata. 


Genus  leioclema  Ulrich,  1882 
Leioclema  orbicularis  Modzalevskaya,  1953 
Plate  2,  figs  5-8;  Plate  3,  figs  I and  2 
1921  Leioclema  spineum  ramosum  Bekker,  p.  41,  pi.  6,  figs  14  18. 

1953  Leioclema  spineum  Ulrich  var.  orbicularis  Modzalevskaya,  p.  147,  pi.  9,  figs  4-6;  text-fig.  23. 

Material.  BMNH  PD8159-8164,  8166 a,b\  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse 
Hill  diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 


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PALAEONTOLOGY,  VOLUME  34 


Other  occurrences.  ?Kuckers  Stage  (middle  Ordovician),  NE  Estonia,  USSR.  Middle  Ordovician,  Leningrad 
Oblast’.  USSR  (Modzalevskaya  1953). 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  6-4  mm  in  diameter.  Autozooecia  are  roughly 
parallel  to  the  branch  axis  within  the  endozone  and  gradually  curve  outwards  to  meet  the  zoarial  surface  at 
70°-90°.  Autozooecial  walls  are  thin  within  the  endozone  and  slightly  wavy.  The  exozone  has  an  average 
diameter  of  1 -66  mm,  and  is  recognized  by  a thickening  of  the  zooecial  walls.  Autozooecia  originate  within  the 
endozone,  where  they  are  polygonal-rounded  in  transverse  section.  They  become  rounded-petaloid  in  the 
exozone,  as  seen  in  tangential  sections  of  branches.  Autozooecial  diameters  in  the  exozone  average  0-25  mm 
by  0-34  mm.  Diaphragms  are  rare  and  often  absent.  If  present,  there  are  usually  only  one  or  two  per 
autozooecium  and  they  are  located  in  the  exozone. 

Mesozooecia  are  common,  originate  within  the  endozone  and  have  an  average  maximum  diameter  of 
016  mm.  In  shallow  tangential  sections  they  are  polygonal-rounded  in  shape.  Mesozooecia  contain  abundant 
orally  deflected  basal  diaphragms,  spaced  on  average  015  mm  apart  in  the  endozone  and  0 08  mm  in  the 
exozone,  with  successive  diaphragms  generally  increasing  in  thickness  distally  along  the  mesozooecium. 

Acanthostyles  are  large  and  abundant,  with  an  average  diameter  of  01  mm  and  density  of  8 mm"2.  They  can 
occur  throughout  the  exozone  and  they  frequently  indent  the  autozooecial  apertures  to  produce  a petaloid 
shape.  A hyaline  calcite  core  is  surrounded  by  steeply  dipping  conical  laminae. 

Autozooecial  wall  thickness  averages  012  mm  in  the  exozone.  Microstructure  is  difficult  to  distinguish 
because  the  walls  are  considerably  disrupted  by  the  presence  of  the  large  acanthostyles ; however,  walls  can  be 
seen  to  be  composed  of  steeply  inclined,  U-shaped  laminae.  Diaphragms  in  the  distal  exozone  are  continuous 
with  the  zooecial  wall  laminae.  Some  of  the  zooecia,  especially  mesozooecia,  become  infilled  with  laminar 
calcite  close  to  the  zoarial  surface.  In  longitudinal  section  this  infilling  consists  of  broad  U-shaped  laminae. 

Remarks.  This  species  is  characterized  by  an  erect  colony  form,  and  thin  autozooecial  walls  in  the 
endozone  which  become  thickened  in  the  exozone.  Autozooecial  apertures  are  rounded-petaloid  in 
shallow  tangential  section.  Diaphragms  are  rare  in  autozooecia  but  common  in  mesozooecia. 
Acanthostyles  are  large  and  abundant  in  the  exozone. 

Leioclema  spineum  Ulrich  var.  orbicularis  Modzalevskaya,  1953  was  first  described  from  the 
middle  Ordovician  of  Leningrad  Oblast’  and  Estonia.  The  L.  spineum  Ulrich  as  described  by  Bassler 
(1911)  was  characterized  by  a ramose  colony  form,  numerous  diaphragms  in  the  abundant 
mesozooecia  and  occasional  ones  in  the  autozooecia,  and  exceedingly  large  acanthostyles.  L. 
spineum  orbicularis  differs  from  L.  spineum  in  having  more  abundant  smaller  acanthostyles  and 
fewer  mesozooecia.  This  internal  structure  is  similar  to  Leioclemella  clava  Bassler,  1911.  The  genus 
Leioclemella  is,  however,  characterized  by  having  a club-shaped  zoarium  seemingly  jointed  at  the 
base.  Articulation  is  unknown  in  trepostomes  and  this  feature  may  instead  be  a paraboloid  base  of 
the  sort  described  by  McKinney  (1977).  The  differences  between  L.  spineum  orbicularis  and 
L.  spineum  are  herein  considered  to  be  significant  enough  to  raise  the  subspecies  L.  spineum 
orbicularis  to  species  rank. 

The  specimens  described  here  are  very  similar  to  L.  orbicularis  from  the  USSR.  Although  the 
acanthostyles  of  the  Welsh  material  are  larger  than  those  shown  in  Modzalevskaya  (1953,  text-fig. 
23),  her  tangential  sections  are  deeper  than  those  of  the  Welsh  material. 


EXPLANATION  OF  PLATE  2 

Fig.  I . Dekayia  pengawsensis  sp.  nov.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  BMNH  PD8176  (holotype),  longitudinal  section,  showing  ‘cyst’ 
structures,  x 120. 

Figs  2-4.  Dekayia  cf.  crenulata  Prantl,  1940.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  2,  BMNH  PD8 1 72.  longitudinal  section,  x 28.  3,  BMNH 
PD8173,  longitudinal  section,  x28.  4,  BMNH  PD8172,  tangential  section,  showing  acanthostyles,  x38. 

Figs  5-8.  Leioclema  orbicularis  Modzalevskaya,  1953.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  5,  BMNH  PD8I61,  longitudinal  section,  x 15.  6,  BMNH 
PD8161,  longitudinal  section,  showing  the  endozone,  x28.  7,  BMNH  PD8161,  longitudinal  section, 
showing  large  acanthostyles  in  the  exozone,  x 55.  8,  BMNH  PD8161,  transverse  section,  x28. 


PLATE  2 


BUTTLER,  Dekayia , Leioclema 


86 


PALAEONTOLOGY,  VOLUME  34 


Bekker  (1921)  described  the  variety  L.  spineum  ramosum  from  the  Kuckers  Stage  (middle 
Ordovician)  of  NE  Estonia,  which  he  regarded  as  an  intermediate  form  between  L.  spineum  and 
Leioclemella  clava.  Bekker  explained  ‘The  acanthostyles  of  my  specimen  agree  much  more  with 
those  of  Leioclemella , but  the  habit  of  growth  ( Leioclemella  clava  - clubshaped)  separates  them’. 
This  would  suggest  that  L.  spineum  ramosum  is  an  erect  ramose  form,  but  Bekker’s  plate  (1921,  pi. 
6,  fig.  18)  shows  the  cone-shaped  origin  of  the  colony  suggesting  a possible  paraboloid  base  like  that 
of  Leioclemella.  The  illustrations  are,  however,  poor  and  the  type  material  (housed  in  the  Geological 
Museum  at  the  University  of  Tartu,  Estonia)  would  have  to  be  examined  for  a positive 
identification,  pending  which  this  species  is  tentatively  placed  within  L.  orbicularis. 


Family  halloporidae  Bassler,  1911 
Genus  hallopora  Bassler,  1911 

Hallopora  peculiaris  Pushkin  (in  Ropot  and  Pushkin,  1987) 

Plate  3,  figs  3-8 

1987  Hallopora  wesenbergiana  peculiaris  Pushkin  in  Ropot  and  Pushkin;  p.  153,  pi.  8,  fig.  5;  pi.  9, 
fig.  1. 

Material.  BMNH  PD8237-82,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170) 

Other  occurrence.  Piriguskii  Stage  (lower  Ashgill),  Shikipi,  Latvia,  USSR  (Pushkin  in  Ropot  and  Pushkin 
1987). 

Description.  Zoaria  erect  with  cylindrical  branches  on  average  8 3 mm  in  diameter.  Autozooecia  curve 
gradually  away  from  the  branch  axis  in  the  endozone  and  meet  the  zoarial  surface  at  approximately  80-90°. 
In  the  endozone  the  zooecial  walls  are  very  thin.  The  exozone,  recognized  by  a thickening  of  the  zooecial  walls, 
has  an  average  width  of  L65  mm.  Autozooecia  are  circular  in  transverse  section  throughout  the  colony  and 
average  0 37  mm  in  diameter  in  the  exozone.  There  is  an  average  of  5 autozooecia  mm"2  in  the  exozone. 
Diaphragms  are  rare  within  the  autozooecia  and  when  present,  usually  occur  closely  spaced  in  the  distal 
exozone.  These  basal  diaphragms  are  deflected  orally  at  their  junctions  with  the  zooecial  walls  and  their 
laminae  are  generally  continuous  with  the  zooecial  linings.  The  average  spacing  between  the  diaphragms  is 
016  mm  in  the  endozone  and  015  mm  in  the  exozone. 

Mesozooecia  are  common  throughout  the  whole  zoarium,  often  originating  in  the  inner  parts  of  the 
endozone.  Mesozooecial  walls  are  thin  in  the  endozone  and  thicken  in  the  exozone.  They  are  polygonal  to 
polygonal-rounded  in  shallow  tangential  sections,  with  an  average  maximum  diameter  of  016  mm  in  the 
exozone.  Basal  diaphragms  are  present  throughout  their  length,  spaced  on  average  0-13  mm  apart  in  the 
endozone  and  0 07  mm  in  the  exozone.  Diaphragms  tend  to  increase  in  thickness  distally  along  the 
mesozooecia.  In  some  colonies  mesozooecial  walls  are  constricted  at  the  position  of  the  diaphragms,  producing 
a slightly  beaded  appearance. 

Autozooecial  wall  thickness  averages  0 08  mm  in  the  exozone.  Wall  microstructure  is  composed  of  steeply 
inclined,  V-shaped  laminae.  The  precise  contact  between  the  zooecia  is  indistinct.  The  thickened  exozonal 


explanation  of  plate  3 

Figs  1 and  2.  Leioclema  orbicularis  Modzalevskaya,  1953.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill), 
A40  Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD8161,  tangential  section,  x 35.  2, 
BMNH  PD8161,  tangential  section,  showing  large  acanthostyles,  x 80. 

Figs  3-8.  Hallopora  peculiaris  Pushkin  (in  Ropot  and  Pushkin,  1987).  Slade  and  Redhill  Beds  (upper 
Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  3,  BMNH  PD8278, 
longitudinal  section,  x 28.  BMNH  PD8282,  longitudinal  section,  x28.  5,  BMNH  PD8278,  transverse 
section,  x28.  6,  BMNH  PD8278,  longitudinal  section,  showing  the  V-shaped  microstructure,  x75.  7, 
BMNH  PD8278,  tangential  section,  showing  rings  of  clear  silica  replacing  the  autozooecial  linings,  x 40.  8, 
BMNH  PD8257,  tangential  section,  showing  maculae  composed  predominantly  of  mesozooecia,  x28. 


PLATE  3 


BUTTLER,  Leioclema , Hallopora 


PALAEONTOLOGY,  VOLUME  34 


diaphragms  in  the  mesozooecia  are  also  laminar  and  are  continuous  with  the  wall  laminae.  Some  zooecia, 
especially  mesozooecia,  are  infilled  with  laminar  calcite  close  to  the  zoarial  surface.  In  longitudinal  sections  this 
infilling  consists  of  broad  U-shaped  laminae. 

Maculae  composed  of  a concentration  of  mesozooecia  have  been  recognized  in  thin  sections  (PI.  3,  fig.  8). 

Overgrowths  are  present  in  several  colonies  (e.g.  PD8237).  These  are  composed  of  endozonal  and  exozonal 
elements,  and  often  contain  abundant  diaphragms. 

Remarks.  Hallopora  peculiaris  is  primarily  characterized  by  the  extensive  beaded  mesozooecia  which 
originate  in  the  inner  endozone.  The  autozooecia  are  circular  throughout  the  colony,  and 
diaphragms  are  rare  in  the  endozone,  becoming  more  abundant  in  the  outermost  regions. 

Pushkin  (in  Ropot  and  Pushkin,  1987)  created  a new  sub-species  H.  wesenbergiana  peculiaris, 
which  differed  from  the  Estonian  H.  wesenbergiana  (Dybowski)  by  the  absence  of  diaphragms 
within  the  endozonal  autozooecia.  The  mesozooecia  in  H.  wesenbergiana  are  less  prominent  than 
in  H.  wesenbergiana  peculiaris  and  are  not  beaded.  The  differences  are  considered  significant  to  raise 
H.  wesenbergiana  peculiaris  to  species  rank. 

One  other  species  of  Hallopora  is  here  described  from  Pengawse  Hill,  H.  cf.  elegantula,  a very 
slender  form,  with  large  and  abundant  mesozooecia. 

Hallopora  peculiaris  is  similar  to  H.  solbergiensis  described  from  the  upper  Ordovician 
Dalmanitina  beds  of  Borenshult,  Ostergotland,  Sweden  by  Brood  (1978).  The  Swedish  species, 
however,  differs  from  the  Welsh  by  its  smaller  size  (colony  branches  3-5  mm  wide),  the  more 
abundant  diaphragms  within  the  autozooecia,  and  the  relatively  greater  size  of  the  mesozooecia. 


Hallopora  cf.  elegantula  (Hall.  1852) 

Plate  4,  figs  1 and  2 

Material.  BMNH  PD8 180-82,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  Zoaria  erect  with  slender  cylindrical  branches,  on  average  3-2  mm  in  diameter.  Autozooecia  curve 
outwards  from  the  branch  axis  to  meet  the  colony  surface  at  90°.  The  autozooecia  within  the  endozone  have 
thin  walls.  The  exozone  is  narrow  with  an  average  width  of  0-86  mm  and  is  recognizable  by  a slight  thickening 
of  the  zooecial  walls. 

Autozooecia  are  circular  in  section  throughout  the  colony  and  average  0-26  mm  by  0-31  mm  in  diameter  in 
the  exozone.  Diaphragms  are  found  along  the  whole  length  of  the  autozooecia,  but  are  rare  in  the  exozone. 
They  are  spaced  on  average  0T7  mm  apart  in  the  endozone. 

Mesozooecia  are  common,  originate  within  the  endozone  and  have  an  average  maximum  diameter  of 
0T5  mm.  In  shallow  tangential  section  the  polygonal  mesozooecia  are  seen  to  fill  in  the  spaces  between  the 
circular  autozooecia.  Mesozooecia  contain  orally  deflected  diaphragms  throughout  their  length  which  are 
spaced  on  average  0-1  mm  apart  in  the  endozone  and  0-05  mm  in  the  exozone,  increasing  in  abundance  distally 
along  each  mesozooecium. 


EXPLANATION  OF  PLATE  4 

Figs  1 and  2.  Hallopora  cf.  elegantula  (Hall,  1852).  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD8181,  longitudinal  section,  x 38.  2,  BMNH 
PD8 181,  transverse  section,  x48. 

Figs  3-6.  IBatostoma  sp.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed.  3,  BMNH  PD8332,  longitudinal  section,  x 32.  4,  BMNH  PD8332,  longitudinal 
section,  showing  large  acanthostyles  which  lack  sheathing  laminae,  x 60.  5,  BMNH  PD8236r/,  transverse 
section,  showing  the  irregularly  shaped  autozooecia  within  the  endozone,  x28.  6,  BMNH  PD8236rf, 
tangential  section,  x48. 

Figs  7-8.  Eridotrypa  sp.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed.  7,  BMNH  PD8319o,  longitudinal  section,  x 38.  8,  BMNH  PD8319m  tangential 
section,  showing  small  acanthostyle-like  structures,  x 105. 


PLATE  4 


BUTTLER,  Hallopora,  Watostonia , Eridotrypa 


90 


PALAEONTOLOGY,  VOLUME  34 


Autozooecial  wall  thickness  averages  01  mm  in  the  exozone.  Wall  microstructure  is  composed  of  inclined, 
U-shaped  laminae.  Zooecial  boundaries  are  indistinct. 

Remarks.  This  species  is  only  known  from  randomly  oriented  peels  of  poorly  preserved  specimens. 
It  is  characterized  by  the  narrow  colony  branches  and  thin-walled  autozooecia  curving  out 
gradually  from  the  branch  axis.  Autozooecia  are  circular  in  cross  section  throughout  the  colony. 
Polygonal  mesozooecia  are  common  and  surround  the  autozooecia.  Diaphragms  are  present  in  the 
autozooecia  and  very  abundant  in  the  mesozooecia. 

Internally,  the  specimens  are  very  similar  to  Hallopora  elegantula  Hall,  an  Ordovician  and 
Silurian  species  with  an  extensive  distribution.  They  have  similar  polygonal  mesozooecia 
surrounding  the  autozooecia,  and  similar  diaphragms.  H.  elegantula  is,  however,  characterized  by 
ornamented,  perforated  terminal  diaphragms  found  usually  at  the  outer  ends  of  the  autozooecia  but 
also  within  the  exozone  (Conti  and  Serpagli  1987).  As  these  have  not  been  observed  in  the  Welsh 
specimens,  this  material  is  therefore  identified  as  H.  cf.  elegantula. 

Family  trematoporidae  Miller,  1889 
Genus  batostoma  Ulrich,  1882 

? Batostoma  sp. 

Plate  4,  figs  3-6 

Material.  BMNH  PD8332,  8236 </,  83196,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse 
Hill  diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  5-3  mm  in  diameter. 

Autozooecia  appear  to  curve  out  from  the  branch  axis  to  meet  the  zoarial  surface  at  70°.  The  autozooecia 
within  the  endozone  have  very  thin  wavy  walls. 

The  exozone  has  an  average  width  of  L37  mm.  It  is  recognized  both  by  a slight  thickening  of  the  zooecial 
walls  and  a change  in  zooecial  orientation. 

Autozooecia  all  originate  in  the  endozone  where  they  are  irregular-polygonal  in  transverse  section,  becoming 
circular  in  the  exozone  as  seen  in  tangential  sections  of  branches.  Autozooecial  diameters  average  0-26  mm  by 
0-31  mm  within  the  exozone.  Diaphragms  are  present  in  autozooecia  in  the  exozone  and  may  also  occur  in  the 
endozone  but  are  hard  to  distinguish  here  owing  to  the  poor  preservation.  These  basal  diaphragms  are  all 
deflected  orally  at  their  junctions  with  zooecial  walls  and  their  laminae  are  continuous  with  the  autozooecial 
linings. 

Mesozooecia  are  present  and  originate  in  the  endozone.  They  are  polygonal  in  shallow  tangential  section  and 
have  an  average  maximum  diameter  of  0-12  mm.  They  contain  orally  deflected  basal  diaphragms  in  the 
exozone,  spaced  on  average  0-2  mm  apart  and  often  slightly  increasing  in  thickness  distally  along  the 
mesozooecium. 

Acanthostyles  are  very  large  and  abundant,  with  an  average  diameter  of  0-06  mm  and  a density  of  10  mm'2. 
They  originate  deep  in  the  exozone,  occasionally  indent  autozooecial  apertures,  and  are  composed  of  a very 
wide  hyaline  calcite  core  without  a surrounding  sheath  of  lamellae. 

Autozooecial  wall  thickness  averages  014  mm  in  the  exozone.  Wall  micro  structure  consists  of  steeply 
inclined  U-shaped  laminae  and  is  hard  to  distinguish  because  of  the  presence  of  the  large  acanthostyles.  Some 
zooecia,  especially  mesozooecia,  are  filled  with  laminar  calcite  close  to  the  zoarial  surface.  In  longitudinal 
section  this  infilling  consists  of  broad  U-shaped  laminae. 

Remarks.  Only  three  poorly-preserved  specimens  (two  in  randomly  oriented  peels)  have  been  found. 
This  species  is  very  unusual  and  is  characterized  by  the  irregularly  polygonal  autozooecial  apertures, 
which  become  circular  in  shallow  tangential  sections.  Autozooecial  walls  are  very  thin  and  irregular 
within  the  endozone  and  become  greatly  thickened  in  the  outer  exozone.  Diaphragms  are  present 
in  the  exozonal  autozooecia  and  are  irregularly  spaced.  Acanthostyles  are  abundant,  large  and 
composed  entirely  of  a hyaline  core  with  no  surrounding  laminae. 

Generic  assignment  of  this  species  is  difficult  because  of  the  poor  preservation  of  the  specimens. 
The  erect  colony,  the  occurrence  of  diaphragms  in  the  autozooecia,  and  the  presence  of 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


91 


acanthostyles  fit  the  generic  concept  of  Batostoma.  However,  the  detailed  structure  of  the 
acanthostyles  and  endozonal  walls  is  apparently  unique  and  provides  a basis  for  the  suggestion  that 
this  material  may  represent  a new  genus.  The  large,  simple  acanthostyles  are  similar  to  those 
observed  in  early  Ordovician  forms  such  as  Nekhorosheviella  Modzalevskaya.  As  three  poorly 
preserved  specimens  do  not  provide  sufficient  information  to  erect  a new  genus,  the  assignment  is 
given  tentatively  as  ? Batostoma  sp. 

Genus  eridotrypa  Ulrich,  1893 
Eridotrypa  sp. 

Plate  4,  figs  7 and  8 

Material.  BMNH  PD8319a,  8236e,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  Zoaria  erect  with  very  narrow  cylindrical  branches,  on  average  1-5  mm  in  diameter. 
This  species  has  only  been  recognized  in  randomly  oriented  peels.  Autozooecia  are  parallel  to  the 
branch  axis  within  the  endozone  and  then  curve  slightly  in  the  exozone  to  meet  the  zoarial  surface 
at  45°.  The  autozooecia  within  the  endozone  have  thin,  straight  walls.  The  exozone  is  narrow  with 
an  average  diameter  of  0-53  mm.  It  is  recognized  by  a slight  thickening  of  the  zooecial  walls. 
Autozooecia  all  originate  in  the  endozone  (though  no  specimens  have  been  observed  in  transverse 
section),  and  are  oval  in  the  exozone,  as  seen  in  tangential  sections  of  the  branches.  Autozooecial 
diameters  average  01 1 mm  by  015  mm  within  the  exozone.  Diaphragms  are  present  throughout  the 
autozooecia  and  are  widely-spaced,  on  average  0-21  mm  apart  in  the  endozone  and  0-12  mm  in  the 
exozone.  These  basal  diaphragms  are  all  deflected  orally  at  their  junctions  with  zooecial  walls. 

Small  polygonal  mesozooecia  may  be  present  in  the  exozone,  but  are  hard  to  distinguish. 
Acanthostyle-like  structures  have  been  observed  in  the  exozone;  their  structure  cannot  be 
distinguished. 

Autozooecial  wall  thickness  averages  0 04  mm  in  the  exozone.  Wall  microstructure  is  composed 
of  steeply  inclined,  V-shaped  laminae,  but  is,  however,  indistinct. 

Remarks.  The  specimens  of  Eridotrypa  from  Pengawse  Hill  are  from  randomly  orientated  peels. 
They  are  characterized  by  a narrow  ramose  colony  form;  autozooecial  walls  are  thin  and 
diaphragms  are  found  throughout  the  colony.  Autozooecial  apertures  are  oval  in  shallow  tangential 
sections;  mesozooecia  are  present. 

Suborder  amplexoporoidea  Astrova,  1965 
Family  amplexoporoidae  Miller,  1889 
Genus  anaphragma  Ulrich  and  Bassler,  1904 

Anaphragma  dnestrense  Astrova,  1965 

Plate  5,  figs  1-4 

1965  Anaphragma  dnestrense  Astrova,  p.  235,  pi.  56,  figs  la  and  b. 

1966  Anaphragma  portranense  Ross,  p.  Ill,  pi.  1,  figs  1,  2,  4,  6;  pi.  6,  figs  4,  6. 

Material.  BMNH  PD8204—34,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Other  occurrences.  Molodovskii  Stage  (upper  Ordovician),  Podolia,  USSR  (Astrova  1965).  Portrane  Limestone 
(Cautleyan,  Ashgill),  Portrane,  Co.  Dublin,  Ireland  (Ross  1966). 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  6-4  mm  in  diameter.  The  surfaces  of  all 
specimens  are  abraded.  Autozooecia  generally  parallel  the  branch  axis  in  the  endozone.  They  then  gradually 
curve  outwards  to  meet  the  zoarial  surface  at  approximately  80°.  Within  the  endozone  the  autozooecial  walls 


92 


PALAEONTOLOGY,  VOLUME  34 


are  thin  and  crenulated.  The  exozone,  recognized  by  a slight  thickening  of  the  zooecial  walls  and  a change  in 
the  orientation  of  the  zooecia,  has  an  average  diameter  of  1-34  mm.  Autozooecia  are  polygonal  in  the  endozone 
in  transverse  section  and  become  rounded  in  the  exozone  as  seen  in  tangential  sections  of  branches. 
Autozooecia  average  0-33  mm  by  0-43  mm  diameter  in  the  exozone.  Diaphragms  are  absent  in  all  of  the 
autozooecia. 

Exilazooecia  are  common  and  originate  in  the  outer  parts  of  the  endozone.  They  are  rounded-polygonal  in 
shape  in  shallow  tangential  sections,  with  a maximum  diameter  which  averages  0T6  mm. 

Acanthostyles  are  abundant,  usually  small  and  inconspicuous.  Their  diameter  ranges  from  0-01  mm  to 
0-06  mm.  In  some  acanthostyles  a calcite  hyaline  core  has  been  observed,  surrounded  by  conical  calcite 
laminae. 

Autozooecial  wall  thickness  averages  0-08  mm  in  the  exozone.  Wall  microstructure  is  composed  of  steeply 
inclined,  V-shaped  laminae.  Zooecial  boundaries  are  distinguished  by  a darker  granular  zone.  Some 
autozooecia  and  exilazooecia  are  infilled  with  laminar  calcite  close  to  the  zoarial  surface.  In  longitudinal 
section  this  infilling  consists  of  broad  U-shaped  laminae. 

Overgrowths,  composed  of  exozonal  elements,  have  been  recognized  in  a few  specimens. 

Remarks.  Anaphragma  dnestrense  was  described  from  the  Molodovskii  Stage  of  Podolia  in  the 
Arctic  Soviet  Union  by  Astrova  (1965)  and  has  hitherto  not  been  recognized  elsewhere.  A. 
portranense  was  described  by  Ross  (1966)  from  the  Portrane  Limestone  in  Ireland.  It  was  diagnosed 
as  ‘ Anaphragma  with  slender  branches  having  large  zooecial  openings,  numerous  small 
acanthopores  which  penetrate  the  junctions  of  the  zooecial  walls  and  mesopore  walls,  and  numerous 
mesopores’.  A.  dnestrense  is  similar  in  most  aspects  to  A.  portranense.  The  colony  size  of  the  Welsh 
material  (4-9  mm  zoarial  diameter)  is  generally  larger  than  that  of  A.  portranense  (3  mm);  however, 
the  Soviet  material  has  a very  wide  range  of  colony  size  (3-14  mm)  spanning  the  two  groups.  All 
other  measurements  given  for  the  holotype  of  A.  portranense  (Ross  1966,  p.  1 12)  extend  into  the 
range  measured  from  the  Welsh  specimens  of  A.  dnestrense.  Therefore,  A.  portranense  is  placed  in 
synonymy  with  A.  dnestrense. 

A.  dnestrense  is  similar  to  A.  mirabile  Ulrich  and  Bassler,  1904  which  was  redescribed  by 
Boardman  (1960).  A.  mirabile  has  been  recognized  from  the  upper  Ordovician  of  North  America 
(Richmondian  Group,  Illinois  and  Wisconsin)  and  Estonia  (Lyckholm  Limestone,  Island  of  Dago). 
However,  the  walls  of  A.  mirabile  are  less  crenulated  in  the  endozone,  there  are  fewer 
exilazooecia,  and  the  exozone  is  larger  in  relation  to  the  endozone  than  in  A.  dnestrense.  In  the  outer 
exozone  of  A.  mirabile  the  acanthostyles  become  very  large  (Boardman  1960,  pi.  4,  fig.  2),  whereas 
in  A.  dnestrense  they  remain  small. 

One  other  species  of  Anaphragma  has  been  recognized  in  this  study  from  the  same  locality 
(Pengawse  Hill,  near  Whitland).  A.  gwyndyense  sp.  nov.  has  thick  walls  in  the  endozone,  tabulated 
polymorphs  (i.e.  mesozooecia)  and  rare  acanthostyles  which  distinguish  it  from  A.  dnestrense. 

Anaphragma  gwyndyense  sp.  nov. 

Plate  5,  figs  5-8;  Text-Fig.  2c 

Holotype.  BMNH  PD8195,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed,  Wales  (SN  164170). 


EXPLANATION  OF  PLATE  5 

Figs  1-4.  Anaphragma  dnestrense  Astrova,  1965.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD8232,  longitudinal  section,  x 28.  2,  BMNH 
PD8229,  longitudinal  section,  x28.  3,  BMNH  PD8235,  tangential  section,  x 38.  4,  BMNH  PD8235, 
tangential  section,  showing  small  acanthostyles  within  the  walls,  x 110. 

Figs  5-8.  Anaphragma  gwyndyense  sp.  nov.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse 
Hill  diversion,  west  of  Whitland,  Dyfed.  5,  BMNH  PD8195  (holotype),  longitudinal  section,  showing  the 
thick  crenulated  walls  within  the  endozone,  x 28.  6,  BMNH  PD8196  (paratype),  longitudinal  section,  x48. 
7,  BMNH  PD8195  (holotype),  tangential  section,  x48.  8,  BMNH  PD8192  (paratype),  tangential  section, 
showing  small  acanthostyles  in  the  zooecial  walls,  x 110. 


PLATE  5 


BUTTLER,  Anaphragma 


94 


PALAEONTOLOGY,  VOLUME  34 


Paratypes.  BMNH  PD8 183-8 194,  8196-8200,  8303-8305;  same  locality  and  horizon  as  holotype. 

Etymology.  The  species  is  named  after  Gwyndy  Farm,  which  is  adjacent  to  the  type  locality. 

Diagnosis.  Colony  ramose.  Zooecia,  with  thick  crenulated  walls  in  endozone,  parallel  branch  axis, 
then  curve  gradually  out  to  meet  zoarial  surface.  Autozooecia  polygonal  in  transverse  section;  oval- 
circular  in  shallow  tangential  sections.  Mesozooecia  oval,  originating  in  outer  endozone. 
Diaphragms  rare  in  autozooecia,  present  in  mesozooecia.  Acanthostyles  extremely  rare;  small  and 
inconspicuous  in  exozone. 

Description.  Zoaria  erect  with  cylindrical  branches,  on  average  5 2 mm  in  diameter.  The  surfaces  of  all 
specimens  are  slightly  abraded.  Autozooecia  generally  parallel  the  branch  axis  in  the  endozone  and  then  curve 
outwards  gradually  to  meet  the  zoarial  surface.  The  autozooecia  within  the  endozone  have  thick,  highly 
crenulated  walls.  The  exozone  is  usually  narrow  with  an  average  diameter  of  1-4  mm.  It  is  recognized  by  a 
thickening  of  the  zooecial  walls.  Autozooecia  originate  in  the  endozone  where  they  are  polygonal  in  transverse 
section,  becoming  oval-circular  in  the  exozone,  as  seen  in  tangential  sections  of  branches.  Autozooecial 
diameters  average  0 33  mm  by  0-25  mm  within  the  exozone.  Diaphragms  are  usually  absent  in  the  autozooecia 
and,  if  present,  only  one  or  two  are  found.  These  basal  diaphragms  are  deflected  orally  at  their  junctions  with 
zooecial  walls.  The  diaphragm  laminae  are  all  continuous  with  the  autozooecial  linings. 

Mesozooecia  are  common  and  originate  in  the  endozone,  their  maximum  diameter  averaging  014  mm.  They 
are  oval  in  shape  in  shallow  tangential  sections.  Orally  deflected  basal  diaphragms  are  common  in  the  exozone 
and  are  spaced  on  average  O il  mm  apart. 

Acanthostyles  are  rare;  when  present  (e.g.  PD8192),  they  are  usually  small  and  very  inconspicuous  and  occur 
in  the  outer  exozone;  their  structure  is  indistinct  (PI.  5,  fig.  8). 

Autozooecial  wall  thickness  averages  0 08  mm  in  the  exozone.  Wall  microstructure  is  composed  of  steeply 
inclined,  U-shaped  laminae  and  the  wall  boundaries  are  dark  and  granular.  The  thickness  of  the  cndozonal 
walls  enables  the  microstructure  to  be  clearly  seen  within  them.  Some  zooecia,  especially  mesozooecia,  are 
infilled  with  laminar  calcite  close  to  the  zoarial  surface.  In  longitudinal  section  this  infilling  consists  of  broad 
U-shaped  laminae. 

Conspecific  overgrowths  have  been  recognized  in  a few  specimens  (e.g.  PD8186).  They  appear  continuous 
with  the  underlying  branch  suggesting  that  they  are  intrazoarial  overgrowths.  The  overgrowths  are  composed 
of  exozonal  components. 

Remarks.  Anaphragma  gwyndyense  is  distinguished  by  the  thick,  highly  crenulated  nature  of  the 
endozonal  walls,  the  numerous  diaphragms  in  the  mesozooecia  and  the  small  rare  acanthostyles. 
This  species  is  assigned  to  Anaphragma  because  it  fits  the  redefined  genus  concept  proposed  by 
Boardman  (1960).  Species  of  Anaphragma  possess  common  laminate  acanthostyles  whose  size  can 
be  extremely  variable.  However,  in  virtually  all  specimens  of  A.  gwyndyense  acanthostyles  have  not 
been  recognized.  This  may  partly  be  because  the  majority  of  the  tangential  sections  are  relatively 
deep  and  acanthostyles  are  only  found  in  the  very  outer  exozone.  Alternatively,  they  may  be  truly 
absent. 

A.  shucknellense  was  described  by  Owen  (1962)  from  the  Aymestry  Limestone  (Ludlow  Series, 
upper  Silurian),  Ludlow  District.  This  species  has  a few  thin  diaphragms  within  the  autozooecia; 
mesozooecia  and  acanthostyles  are  absent.  This  is  the  only  species  of  Anaphragma  previously 
described  from  the  Welsh  Basin. 

A.  gwyndyense  is  similar  to  A.  mirabile  Ulrich  and  Bassler,  1904,  known  from  the  upper 
Ordovician  of  North  America  and  Estonia,  but  is  primarily  distinguished  by  the  presence  of 
mesozooecia,  the  thick  crenulated  endozonal  walls,  and  the  rare  acanthostyles.  Three  other  species 
of  Anaphragma  have  been  recognized  from  the  USSR;  A.  mirabile  var.  cognata  Bassler,  1911;  A. 
vetustum  Modzalevskaya,  1953;  and  A.  minutum  Astrova,  1965.  A.  gwyndyense  is  readily 
distinguished  from  these  species  by  the  numerous  diaphragms  within  the  mesozooecia.  A. 
gwyndyense  is  very  similar  to  Hallopora  anaphragmoides  Pushkin,  1987  (in  Ropot  and  Pushkin, 
1987),  described  from  White  Russia.  Acanthostyles  are  apparently  absent  in  the  Russian  species, 
whereas  they  have  been  recognized,  albeit  rarely,  in  A.  gwyndyense. 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


95 


Order  fenestrata  Elias  and  Condra,  1957 
Suborder  phylloporina  Lavrentjeva,  1979 
Family  chasmatoporidae  Schulga-Nesterenko,  1955 
Genus  pinnatoporella  gen.  nov. 
non  1884  Pinnatopora  Vine;  p.  191. 

1884  Pinnatopora  Shrubsole  (in  Shrubsole  and  Vine);  p.  330. 

1885  Pinnatopora  Shrubsole;  p.  100. 

Type  species.  Ramipora  hochstetteri  var.  carinata  Etheridge,  1879:  Bala  Beds  (upper  Ordovician  Caradoc), 
Corwen,  Gwynedd,  Wales. 

Diagnosis.  Colonies  erect  and  pinnate,  branches  at  same  height  on  opposite  sides  of  the  parent 
branch.  Tertiary  branches  may  anastomose.  Autozooecia  in  two  longitudinal  rows  on  the  frontal 
side  of  the  colony.  Central  ridge  and  striae  on  colony  reverse. 

Remarks.  Pinnatoporella  is  similar  to  the  Carboniferous  genus  Penniretepora  d’Orbigny,  1849 
(redescribed  by  Olaloye  1974).  Both  genera  have  two  longitudinal  rows  of  ovoid  zooecial  apertures 
on  the  front  of  the  colony,  and  a central  ridge  with  striae  on  the  reverse.  The  difference  between 
them  is  that  the  branches  of  Pinnatoporella  often  anastomose  but  this  never  occurs  in  Penniretepora 
(Olaloye  1974).  The  Silurian  genus  Arcanopora  Shrubsole  and  Vine,  1882u  differs  from 
Pinnatoporella  by  the  large  open  apertures  (zooecia  lack  frontal  walls)  and  the  presence  of  three  or 
more  rows  of  autozooecia. 

The  generic  status  of  Glauconome  Goldfuss,  1829  (non  Gray,  1828),  Penniretopora  d’Orbigny, 
1849,  Pinnatopora  Vine,  1884  and  Pinnatopora  Shrubsole  (in  Shrubsole  and  Vine,  1884)  has 
frequently  been  discussed  (e.g.  Ross  1966,  p.  121 ; Olaloye  1974,  p.  474;  Spjeldnaes  1983,  p.  17).  A 
summary  of  the  nomenclatural  history  is  given  below  with  some  new  evidence  regarding  the  validity 
of  the  genus  ‘ Pinnatopora  ' and  its  relationship  to  Pinnatoporella. 

Goldfuss  (1829)  created  the  genus  Glauconome  and  mentioned  four  species,  all  Tertiary 
cheilostomes  from  the  Eiffel.  In  1831  he  described  a fifth  species,  G.  distincta  from  the  Silurian  of 
Dudley.  Lonsdale  (1839)  redefined  the  genus  based  on  additional  material  from  the  Wenlock 
Limestone  of  Dudley,  and  not  on  Goldfuss’  original  specimens.  Lonsdale  made  G.  distincta  the  type 
species,  but  this  was  invalid  because  the  species  was  not  available  as  the  type.  The  Silurian  G. 
distincta  has  more  than  two  rows  of  zooecia  on  each  branch,  and  the  zooecia  have  large  open 
apertures. 

The  new  Glauconome  is,  however,  preoccupied  by  Glauconome  Gray,  1828  (a  bivalve).  In  an 
abstract  by  Shrubsole  and  Vine  (1882«,  b ) a new  genus  Arcanopora  was  proposed  with  G.  distincta 
named  as  the  type  species.  Vine  later  ( 1 884)  gave  the  species  Flustra  ( ? ) parallela  Phillips  as  the  type 
of  Arcanopora  but  this  is  invalid  as  the  type  species  has  already  been  validly  designated.  Bassler 
(1952)  proposed  Glauconomella  as  a new  name  for  Glauconome  Goldfuss,  citing  G.  distincta  as  the 
type  species.  As  Glauconomella  Bassler,  1952  and  Arcanopora  Shrubsole  and  Vine,  1882a  share  the 
same  type  species,  Glauconomella  is  a junior  objective  synonym  of  Arcanopora. 

In  1849  d’Orbigny  proposed  the  genus  Penniretepora , with  the  type  species  Retepora  pluma 
Phillips.  This  is  a Carboniferous  species  with  two  rows  of ‘box-like’  zooecia  having  ovoid  apertures. 
In  1850  d’Orbigny  redescribed  Penniretepora , making  G.  distincta  (sensu  Lonsdale)  the  type  species 
and  renaming  it  P.  londsdalei.  This  action  is  invalid  and  R.  pluma  remains  the  type  species  of 
Penniretepora. 

Two  papers  were  published  in  1884,  one  by  Shrubsole  and  Vine,  the  other  by  Vine,  both 
proposing  Pinnatopora  as  a new  genus.  In  Vine’s  paper  of  1884,  no  type  species  was  given  but  nine 
Carboniferous  species  were  mentioned,  including  Pinnatopora  elegans  Young  and  Young  which  was 
illustrated.  Pinnatopora  has  since  been  placed  in  synonymy  with  Penniretopora  by  Bassler  (1935).  In 
the  1884  paper  by  Shrubsole  and  Vine,  no  type  species  was  designated  but  as  only  Pinnatopora 
sedgwicki  was  described,  this  would  be  regarded  as  the  type  species  by  monotypy;  P.  sedgwicki  is 
an  Ordovician  species  with  two  rows  of  autozooecia  and  ovoid  apertures.  This  species  has  been 


96 


PALAEONTOLOGY,  VOLUME  34 


table  1 . Summary  of  the  biometric  details  of  all  trepostome  species  from  the  Slade  and  Redhill  Beds,  near 
Whitland. 


Species 

zow 

EXW 

MXZD 

MNZD 

MXMD 

Heterotrypa  sladei 

7-5“  (4)b 

1-26  (4) 

0-27  (4) 

0-23  (4) 

O il  (4) 

5-5-1 0-01' 

1 14-1-43 

0-21-0-32 

0-17-0-3 

0-06-0- 1 7 

Dekayia  pengawsensis 

11-0  (3) 

— 

0-32  (3) 

0-29  (3) 

0 12  (3) 

8-0-130 

0-27-0-38 

0-23-0-36 

0-04-0-19 

Dekayia  cf.  crenulata 

7-0  (3) 

11  (2) 

0-27  (2) 

0-22  (2) 

0-12  (2) 

6-0-8  0 

1-05-114 

0-23-0-32 

0-19-0-29 

008-0-15 

Leioclema  orbicularis 

6-38  (8) 

1-66  (8) 

0-34  (8) 

0-25  (8) 

0 16  (8) 

5-0-90 

1-33-2-09 

0-25-0-44 

0-13-0-36 

01-0-25 

Hallopora  peculiaris 

8-3  (46) 

1-65  (43) 

0-37  (41) 

0-32  (41) 

0 16  (40) 

5-0-130 

1-33-2-28 

0-13-0-57 

0-19-0-48 

0-06-0-29 

Hallopora  cf.  elegantula 

3-17  (3) 

0-86  (1) 

0-31  (3) 

0-26  (3) 

0-15  (3) 

2- 5-4-0 

0-86-0-86 

0-25-0-38 

0-19-0-34 

0-1-019 

Eridotrypa  sp. 

1-5  (2) 

0-53  (2) 

0-15  (2) 

0 19  (2) 

01  (1) 

1-5-1 -5 

0-38-0-67 

0-130-19 

0-1-013 

0-1-0  1 

Anaphragma  dnestrense 

6-43  (35) 

1-34  (18) 

043  (34) 

0-33  (34) 

— 

4-0-9-0 

0-95-1-71 

0-29  0-61 

0-23-0-42 

A naphragma  gwyndyense 

5-2  (20) 

1.35  (15) 

0-33  (13) 

0-25  (13) 

0-14  (13) 

4-0-7-0 

0-95-1-9 

0-1 9-0-49 

0-17-0-4 

0-06-0-29 

Species 

MXED 

ZWT 

ZMM 

DEX 

DEN 

Heterotrypa  sladei 

— 

0-04  (4) 

9-36  (4) 

013  (4) 

0-32  (4) 

0-02-0-06 

7-0-11-0 

0-06-0-21 

0-13-0-64 

Dekayia  pengawsensis 

— 

0-02  (3) 

9-14  (3) 

— 

0-48  (3) 

0-02-004 

7-0-11-0 

013-0-86 

Dekayia  cf.  crenulata 

— 

0-03  (2) 

8-57  (3) 

0-25  (2) 

— 

0-02-0-04 

7-0-10-0 

01-0-42 

Leioclema  orbicularis 

— 

0-12  (8) 

4-38  (8) 

0-4  (1) 

0-23  (3) 

0-04-0-19 

3-5-60 

0-4-0-4 

0 13-0-38 

Hallopora  peculiaris 

— 

0-08  (41) 

5-24  (40) 

0 15  (14) 

0-16  (2) 

0-02-0-17 

3-0-8-0 

002-0-29 

0 1 1-0-23 

Hallopora  cf.  elegantula 

— 

O il  (3) 

4-9  (3) 

— 

0-17  (3) 

006-0-21 

4-0-60 

01-0-23 

Eridotrypa  sp. 

— 

0-04  (2) 

— 

0-12  (2) 

0-21  (2) 

0-02-0-06 

0 08-0-21 

0-08-0-34 

Anaphragma  dnestrense 

0-16  (34) 

0 08  (32) 

4-6  (34) 

— 

— 

0-04-0-38 

0-02-0-19 

3-0-7-0 

A naphragma  gwyndyense 

— 

0-08  (15) 

6-22  (14) 

0-24  (10) 

0-22  (2) 

0-04-0-21 

4-0-8-0 

0 1 1-0-32 

0-1-0-32 

Species 

DM  EX 

DMEN 

AD 

AZ 

AMM 

Heterotrypa  sladei 

0-1  (4) 

0-18  (2) 

0 04  (4) 

1-84  (3) 

8-8  (3) 

006-0-15 

0-08-0-27 

0-03-0-06 

1 -0-3-0 

5-0-12-0 

Dekayia  pengawsensis 

0-11  (3) 

— 

0-03  (3) 

— 

5-0  (1) 

0-06-0-23 

0-02-0-05 

5-0-5-0 

Dekayia  cf.  crenulata 

013  (6) 

0-15  (3) 

0-05  (3) 

1-4  (3) 

7-2  (2) 

0-1-0-19 

0-1-0-17 

0-03-0-07 

1 -0-2-0 

6-0-8-0 

Leioclema  orbicularis 

0-08  (8) 

0-15  (6) 

01  (8) 

3-8  (8) 

8-0  (8) 

004-019 

0-08-0-25 

0-08-0-14 

2-0-5-0 

6-0-12-0 

BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


97 


Table  I . (cont.) 


Species 

DMEX 

DMEN 

AD 

AZ 

AMM 

Hallopora  peculiaris 

0-07  (45) 
0-2-0- 1 5 

0 13  (43) 
0-06-0-23 

— 

— 

— 

Hallopora  cf.  elegantula 

0-05  (3) 
002-008 

01  (3) 
0-6-0-17 

— 

— 

— 

Eridotrypa  sp. 

0-056  (2) 
0-04-0-08 

— 

— 

— 

— 

Anaphragma  dnestrense 

— 

0-03  (29) 
0-01-0-06 

10-2  (4) 
4-0-18-0 

12  0 (4) 
4-0-17-0 

— 

A naphragma  gwyndyense 

01 1 (18) 
0-04-0-27 

0 03  (1) 
0-3-0-3 

All  measurements  are  in  mm  except  for  ZMM,  AD  and  AMM.  Abbreviations:  a,  mean;  b,  number  of 
specimens;  c,  range;  ZOW,  zoarial  diameter;  EXW,  exozonal  width;  MXZD,  maximum  autozooecial 
diameter;  MNZD,  minimum  autozooecial  diameter;  MXMD,  maximum  mesozooecial  diameter;  MXED, 
maximum  exilazooecial  diameter;  ZWT,  autozooecial  wall  thickness;  ZMM,  autozooecia  mm"'2;  DEX, 
distance  between  exozonal  autozooecial  diaphragms;  DEN,  distance  between  endozonal  autozooecial 
diaphragms;  DMEX,  distance  between  exozonal  mesozooecial  diaphragms;  DMEN,  distance  between 
endozonal  mesozooecial  diaphragms;  AD,  acanthostyle  diameter;  AZ,  number  of  acanthostyles  per 
autozooecia;  AMM,  acanthostyles  mm-2. 


described  previously  as  Glauconome  sedgwicki  Shrubsole  (in  Shrubsole  and  Vine,  1882).  Spjeldnaes 
(1983)  tried  to  determine  which  of  the  two  1884  papers  appeared  first.  He  discovered  that  Shrubsole 
and  Vine’s  was  published  in  the  Quarterly  Journal  of  the  Geological  Society  of  London  on  1 May, 
1884  and  although  he  could  not  find  the  exact  date  of  issue  of  Vine’s  paper  in  the  Annual  Report 
of  the  British  Association  for  the  Advancement  of  Science,  he  considered  it  to  be  late  in  1884.  He 
therefore  suggested  that  'Shrubsole  and  Vine  1884  was  legally  issued  before  Vine  1884  and  that  P. 
carinata  [which  Spjeldnaes  regarded  as  a senior  synonym  of  P.  sedgwicki ] therefore  is  the  type 
species  of  Pinnatopora 

New  evidence  has  since  been  found  pertaining  to  the  publication  date  of  Vine  (1884).  The  Register 
of  Serial  Publications  at  the  BMNH  records  the  dates  of  acquisitions  to  their  General  Library.  The 
BAAS  Annual  Report  volume  containing  Vine’s  paper  was  acquired  by  the  BMNH  on  30  April 
1884,  one  day  before  Shrubsole  and  Vine  (1884)  was  published.  Therefore  Vine  (1884)  has  priority 
over  Shrubsole  and  Vine  (1884)  and  the  type  species  of  the  genus  Pinnatopora  must  come  from  the 
nine  Carboniferous  species  mentioned  by  Vine  (1884).  Among  these  are  Glauconome  elegans  Young 
and  Young  which  Bassler  (1935)  named  as  the  genotype.  Species  of  the  so-called  Ordovician 
Pinnatopora , as  exemplified  by  P.  carinata , are  inappropriately  assigned  to  Pinnatopora.  They  differ 
from  Carboniferous  species  by  the  very  common  anastomosing  nature  of  their  branches.  The  new 
name  Pinnatoporella  is  herein  proposed  to  encompass  these  species  including  Pinnatopora  sensu 
Shrubsole  (in  Shrubsole  and  Vine,  1884).  One  further  description  of  Pinnatopora  ‘gen.  nov.’ 
Shrubsole  was  published  in  1885,  in  the  Proceedings  of  the  Chester  Society  of  Natural  Sciences.  This 
included  a description  of  the  species  P.  sedgwicki  which  would  be  regarded  as  the  type  by  monotypy. 
However,  Vine  (1884)  has  priority  over  this  publication. 

Distribution.  The  genus  is  currently  known  only  from  Wales. 

Range.  Upper  Ordovician. 


98 


PALAEONTOLOGY,  VOLUME  34 


table  2.  Summary  of  the  nomenclature  and  distinguishing  characteristics  of  the  pinnate  fenestrate  genera 
Pinnatoporella,  Arcanopora  and  Penniretepora 


Genus  and  author 

Valid  type  species 

Age  of  type 
species 

Synonymous 

genera 

Distinguishing 

characteristics 

Pinnatoporella 
gen.  nov. 

Ramipora 
hochstetteri  var. 
carinata 
Etheridge,  1879 

Upper  Ordovician 

Pinnatopora  sensu 
Shrubsole  and 
Vine,  1884 
Pinnatopora  sensu 
Shrubsole,  1885 

Anastomosing 
branches 
2 rows  of 
autozooecia 
Ovoid  zooecial 
apertures 

Arcanopora 
Shrubsole  and 
Vine,  1882 

Glauconome 
distincta 
Goldfuss,  1829 

Middle  Silurian 

Glauconome 
Goldfuss,  1829 
Glauconomella 
Bassler,  1935 

Non-anastomosing 

branches 

3 or  more  rows  of 
autozooecia 
Large  open  zooecial 
apertures 

Penniretepora 

Retepora  pluma 

Lower 

Pinnatopora 

Non-anastomosing 

d'Orbigny,  1849 

Phillips,  1836 

Carboniferous 

Vine,  1884 

branches 
2 rows  of 
autozooecia 
Ovoid  zooecial 
apertures 

Pinnatoporella  carinata  (Etheridge,  1879) 

Plate  6,  figs  1 and  2 

1839  Glauconome  distincta  (pars)  Lonsdale,  p.  49. 

1879  Ramipora  hochstetteri  var.  carinata  Etheridge,  p.  241,  pi.  6. 

1882a  Glauconome  sedgwicki  Shrubsole  (in  Shrubsole  and  Vine),  p.  245. 

18826  Glauconome  sedgwicki  Shrubsole  (in  Shrubsole  and  Vine),  p.  381. 

1884  Pinnatopora  sedgwicki  Shrubsole  (in  Shrubsole  and  Vine),  p.  330. 

1885  Pinnatopora  sedgwicki  Shrubsole,  p.  100. 

1908  Ramipora  hochstetteri  Toula  var.  carinata  Etheridge;  Groom  and  Lake,  p.  572. 

Lectotype.  Designated  herein,  NMW  27. 1 10  G37  (Etheridge  1879,  pi.  6,  fig  la,  h):  Bala  Beds  (Caradoc),  Garth 
Gell,  Corwen,  Gwynedd,  Wales. 

Paralectotypes.  Designated  herein,  BMNH  D48661  (Etheridge  1879,  pi.  4,  fig.  3),  Bala  Beds  (Caradoc), 
Corwen,  Gwynedd,  Wales;  and  BGS  85495-6  (Etheridge  1879,  pi.  4,  fig.  2),  S.  of  Cefn  Coch,  near  Llangollen, 
Gwynedd,  Wales. 

Additional  material.  BMNH  PD8405  (hand  specimen),  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill), 
A40  Pengawse  Hill  diversion,  W.  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Other  occurrences.  Dolhir  Beds  (Ashgill),  Plas  Einion,  and  Pant,  Glyn  Ceiriog,  Gwynedd,  Wales;  upper  Bala 
Beds  (Caradoc),  Corwen,  Gwynedd,  Wales. 

Diagnosis.  As  for  genus. 

Description.  Zoaria  are  erect  and  pinnate,  known  only  from  decalcified  specimens.  The  colony  from  South 
Wales  is  26  mm  in  height  and  32  mm  in  width.  Primary  branches  are  1 mm  in  diameter,  and  secondary 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


99 


branches  04  mm  in  diameter.  Secondary  branches  occur  in  pairs  on  opposite  sides  of  the  main  branch,  and  are 
common;  tertiary  branches  also  occur.  In  the  lectotype,  illustrated  by  Etheridge  (1879,  pi.  6,  fig.  1 b),  V-shaped 
fenestrules  are  observed;  they  appear  to  develop  by  the  fusion  of  adjacent  tertiary  branches. 

The  reverse  surface  of  the  colony  has  a central  ridge  with  striae  on  either  side.  On  the  frontal  side  there  are 
two  longitudinal  rows  of  autozooecia.  Autozooecial  apertures  are  ovoid  in  shape,  and  approximately  015  mm 
in  diameter. 

Remarks.  This  species  is  characterized  by  the  pinnate  colony  form  and  two  longitudinal  rows  of 
ovoid  autozooecia.  The  reverse  sides  of  colonies  have  a central  ridge  and  are  striated. 

The  species  was  first  described  by  Etheridge  (1879)  as  a variety  of  the  species  Ramipora 
hochstetteri  from  the  Permo-Carboniferous  of  Spitzbergen.  Ramipora  hochstetteri  is,  however,  a 
cystoporate  (Utgaard  in  Boardman  et  al.  1983;  Nakrem  1988).  Shrubsole  (in  Shrubsole  and  Vine 
1882)  described  a new  species  Glauconome  sedgwicki  and  two  years  later  (in  Shrubsole  and  Vine 
1884)  re-assigned  it  to  a new  genus,  Pinnatopora.  The  synonymy  list  for  this  species  includes  the 
variety  described  by  Etheridge.  Pinnatopora  Shrubsole  in  Shrubsole  and  Vine,  1884  is  preoccupied 
by  Pinnatopora  Vine,  1884  (discussed  above  p.  95)  and  the  name  Pinnatoporella  is  here  erected.  The 
variety  name  proposed  by  Etheridge  (1879)  is  raised  to  specific  level  and  sedgwicki  becomes  a junior 
synonym.  P.  carinata  is  the  only  known  species  of  Pinnatoporella. 


Order  cystoporata  Astrova,  1964 
Suborder  fistuliporina  Astrova,  1964 
Family  fistuliporidae  Ulrich,  1882 
Genus  fistulipora  M’Coy,  1849 

Fistulipora  sp. 

Plate  6,  figs  3 and  4 

Material.  BMNH  PD8236c,  8385 f Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  Zoaria  are  only  recognized  in  randomly  oriented  peels  and  appear  as  long  bands,  on  average 
1 mm  in  height. 

Autozooecia  are  perpendicular  to  the  base.  Vesicles  are  oval  in  longitudinal  section,  with  irregular  bases 
where  they  interlock.  The  average  distance  between  zooecia  is  0-53  mm.  Zooecial  walls  are  thin  throughout  the 
colony  and  usually  straight,  although  adjacent  vesicular  tissue  can  indent  them,  giving  an  undulating 
appearance.  Vesicular  tissue  is  abundant  between  autozooecia  throughout  the  colony.  There  is  periodically  a 
marked  thickening  of  the  vesicle  roofs  from  0 09  mm  to  015  mm. 

Lunaria  are  present  and  seen  in  longitudinal  section  as  hyaline  rods  on  the  sides  of  the  autozooecia. 

The  microstructure  is  hard  to  distinguish  but  laminar  walls  can  be  identified. 

Remarks.  No  species  of  Fistulipora  have  previously  been  described  from  the  Ordovician  of  the 
Welsh  Basin.  Owen  (1962,  1969)  described  several  Silurian  members  of  the  genus  from  Shropshire. 
F.  strawi  Owen,  1962  has  similar  thin  walls  and  abundant  vesicular  material  to  the  Ordovician 
specimens  but  lacks  basal  diaphragms  and  has  less  distinct  lunaria.  The  species  F.  nummulina 
Nicholson  and  Foord,  1885,  described  by  Owen  (1969)  from  Dudley,  has  similar  distinct  lunaria  to 
the  Pengawse  Hill  material  but  less  abundant  vesicles  and  no  basal  diaphragms.  The  Pengawse  Hill 
species  is  left  in  open  nomenclature  until  more  complete  specimens  can  be  examined. 


100 


PALAEONTOLOGY,  VOLUME  34 


Suborder  ceramoporina  Bassler,  1913 
Family  ceramoporidae  Ulrich,  1882 
Genus  ceramoporella  Ulrich,  1882 

Cercimoporella  distinct  a Ulrich,  1890 

Plate  6,  figs  5-8 

1890  Ceramoporella  distincta  Ulrich,  p.  464,  pi.  39,  figs  6,  6a. 

1908  Ceramoporella  distincta  Ulrich;  Cummings,  p.  799,  pi.  10,  fig.  7;  pi.  11,  figs  2,  2a. 

1909  Ceramoporella  distincta  Ulrich;  Grabau  and  Shimer,  p.  122. 

1953  Ceramoporella  distincta  Ulrich;  Bassler,  p.  G81,  text-figs  44,  2a,  b. 

1968  Ceramoporella  distincta  Ulrich;  Utgaard,  p.  1405,  pi.  181,  fig.  4;  pi.  182,  figs  1-3. 

1973  Ceramoporella  distincta  Ulrich;  Utgaard,  figs  16,  23. 

1984  Ceramoporella  distincta  Ulrich;  Karklins,  p.  189,  pi.  38,  figs  1,  4. 

Material.  PD8386-8388,  8395,  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill 
diversion,  west  of  Whitland,  Dyfed,  Wales  (SN  164170). 


Other  occurrences.  Eden  and  Waynesfield  Formation,  Cincinnati ; Brannon  and  Millersburg  Members, 
Shermaman  Stage,  Lexington  Limestone,  Kentucky. 

Description.  Zoaria  encrusting,  consisting  of  up  to  five  superimposed  layers  of  zooecia.  The  basal  layer, 
observed  in  thin  section,  has  an  average  thickness  of  0-8  mm,  and  the  basal  laminae  of  the  zooecial  layers  have 
a laminated  microstructure.  It  is  difficult  to  distinguish  endozone  from  exozone.  In  the  endozone  the 
autozooecia  are  slightly  recumbent  and  the  zooecial  walls  are  thin  and  straight.  In  the  exozone  the  walls  remain 
straight  and  the  zooecial  apertures  in  shallow  tangential  section  are  circular-polygonal  and  on  average  0-26  mm 
in  diameter.  Lunaria  are  abundant  throughout  the  colony. 

Diaphragms  are  occasionally  present  in  the  autozooecia,  sometimes  pierced  by  pores,  and  apparently 
aborally  deflected  and  continuous  with  the  zooecial  linings.  These  diaphragms  frequently  occur  at  the  same 
level  in  adjacent  zooecia.  Basal  diaphragms  are  rare. 

Small  exilazooecia  are  present  in  the  outer  endozone  and  exozone.  These  contain  no  diaphragms  and  are 
rounded  in  shallow  tangential  section,  on  average  0-09  mm  in  diameter. 

Communication  pores  have  not  been  observed.  Possible  acanthostyle-like  structures  have  been  observed  but 
not  identified  conclusively.  The  microstructure  is  hard  to  distinguish  but  appears  to  be  laminar. 


Remarks.  The  species  is  characterized  by  the  multilayered  zoaria,  thin  autozooecial  walls,  sparse 
diaphragms  and  the  presence  of  distinct  lunaria.  It  is  very  similar  to  Ceramoporella  distincta  Ulrich, 
1890,  recently  re-described  by  Karklins  (1984,  p.  189),  from  the  McMiken  Member,  Eden 
Formation  (upper  Ordovician),  Cincinnati,  Ohio,  USA.  The  main  difference  is  that  the  specimens 
from  Wales  have  fewer  exilazooecia  than  those  from  North  America. 


explanation  of  plate  6 

Figs  1-2.  Pinnatoporella  carinata  (Etheridge,  1879).  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD8405,  mould  of  a pinnate  colony,  x 5.  2, 
BMNH  PD8405,  mould  of  a pinnate  colony  showing  rounded  autozooecial  apertures,  x 9. 

Figs  3—4.  Fistulipora  sp.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse  Hill  diversion, 
west  of  Whitland,  Dyfed.  3,  BMNH  PD8385/,  longitudinal  section,  x48.  4,  BMNH  PD8385/,  longitudinal 
section,  showing  the  vesicular  tissue  between  the  autozooecia  and  lunaria  at  the  side  of  the  autozooecia, 
x 68. 

Figs  5-8.  Ceramoporella  aff.  distincta  Ulrich,  1890.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  5,  BMNH  PD8386,  longitudinal  section,  x 28.  6,  BMNH 
PD8386,  longitudinal  section  showing  specimen  encrusting  a halloporid  colony,  x 18.  7,  BMNH  PD8386, 
longitudinal  section,  showing  subterminal  diaphragms  at  the  same  level  in  adjacent  autozooecia,  x 38. 
BMNH  PD8387,  tangential  section,  showing  lunaria,  x 110. 


PLATE  6 


BUTTLER,  Pinnatoporella,  Fistulipora , Ceramoporella 


102 


PALAEONTOLOGY,  VOLUME  34 


Family  rhinoporidae  Miller,  1889 

Emended  diagnosis.  Zoaria  thin,  encrusting  or  bifoliate.  Autozooecial  apertures  elongate.  Hyaline 
lunaria  present.  Walls  laminated  or  granular-prismatic.  Autozooecia  recumbent  close  to  the  basal 
lamina,  bending  to  become  perpendicular  to  base  in  later  ontogeny.  Small  polygonal  exilazooecia 
present  between  autozooecia.  Communication  pores  often  present,  up  to  three  per  zooecium. 
Anastomosing  tunnel  structures  present,  with  roofs  elevated  above  zoarial  surface,  some  tunnels 
containing  barriers. 

Remarks.  The  family  Rhinoporidae  is  characterized  by  the  unusual  tunnel  structures  found  in  the 
two  constituent  genera  Rhinopora  and  Lichenalia.  It  was  previously  placed  within  the  suborder 
Fistuliporina  because  of  the  occasional  presence  of  blister-like  vesicular  tissue.  This  tissue  has  been 
described  as  irregular,  and  unlike  that  commonly  found  in  fistuliporines.  Vesicular  tissue  has  been 
observed  in  Lichenalia  (Utgaard  in  Boardman  et  al.  1983,  fig.  192,  2b)  but  does  not  appear  to  be 
a consistent  feature  in  all  colonies.  The  tunnel  structures  are  easy  to  mistake  for  vesicles  in  section 
when  they  have  been  overgrown  by  the  colony.  Well-preserved  specimens  of  Rhinopora  and 
Lichenalia  have  been  examined  during  this  study  and  abundant  communication  pores  observed. 
These  are  common  in  the  suborder  Ceramoporina  but  have  not  been  identified  conclusively  in 
Fistuliporina.  Therefore,  the  family  is  herein  reassigned  to  Ceramoporina. 

Genus  lichenalia  Hall  in  Silliman,  Silliman  and  Dana,  1851 

Type  species.  Lichenalia  concentrica  Hall,  1852;  Rochester  Shale  (middle  Silurian),  Lockport,  New  York  State, 
USA;  by  monotypy. 

Emended  diagnosis.  Zoaria  encrusting  with  laminated  basal  layer;  autozooecia  with  long  recumbent 
portion,  walls  thin  and  laminated.  Diaphragms  uncommon.  Small  polygonal  exilazooecia  present 
between  autozooecia.  Lunaria  hyaline,  elevated  at  colony  surface.  Bifurcating  and  anastomosing 
tunnel  structures  are  common,  some  with  internal  partitions.  Communication  pores  may  be  present 
in  exozone. 

Remarks.  The  diagnosis  has  been  revised  from  Utgaard  (in  Boardman  et  al.  1983,  p.  407)  to  include 
the  presence  of  communication  pores. 

Distribution.  The  genus  was  previously  known  from  North  America  and  the  USSR. 

Range.  Upper  Ordovician-middle  Silurian. 


EXPLANATION  OF  PLATE  7 

Figs  1-2.  Lichenalia  cf.  concentrica  Hall,  1852.  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  1,  BMNH  PD9873,  decalcified  colony  showing  unusual 
tunnel  structures  meandering  between  the  autozooecia,  x 15.  2,  BMNH  PD9873,  tunnel  structures,  x 34. 

Figs  3-6.  Lichenalia  cf.  concentrica  Hall.  1852.  Wenlock  Shales  (Homerian,  Wenlock,  Silurian),  Dudley,  West 
Midlands.  3,  BMNH  PD9885,  surface  of  colony  showing  abundant  communication  pores  and  small 
polygonal  mesozooecia,  x31.  4,  BMNH  PD9885,  bifurcating  tunnel  structure,  x 15.  5,  BMNH  PD9885, 
tunnel  overgrown  by  a subsequent  layer  of  the  colony,  x 40.  6,  BMNH  PD  1886,  tangential  section  showing 
bifurcating  tunnel  structures,  x28. 

Figs  7-8.  Kukerse/la  borealis  (Bassler,  1911).  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40 
Pengawse  Hill  diversion,  west  of  Whitland,  Dyfed.  7,  BMNH  PD8154<v,  b , longitudinal  and  transverse 
sections,  x 18.  8,  BMNH  PD8236«,  transverse  section  with  abundant  pseudopores  in  frontal  wall,  x43. 


PLATE  7 


BUTTLER,  Lichenalia,  Kukersella 


104 


PALAEONTOLOGY,  VOLUME  34 
Lichenalia  cf.  concentrica  Hall,  1852 
Plate  7,  figs  1-6 

Material.  BMNH  PD9885-6  (hand  specimens);  Wenlock  Shale,  Dudley,  West  Midlands.  BMNH  PD9871, 
9873,  9874,  9876,  9878  (hand  specimens);  Slade  and  Redhill  Beds  (upper  Rawtheyan,  Ashgill),  A40  Pengawse 
Hill  diversion,  W.  of  Whitland,  Dyfed,  Wales  (SN  164170). 

Description.  All  colonies  are  umlaminate  and  encrusting.  The  Silurian  specimens  encrust  brachiopods,  whereas 
the  Ordovician  material  forms  unilaminar  hollow  cylindrical  colonies  which  may  have  encrusted  a soft-bodied 
organism  such  as  a hydroid. 

Autozooecia  have  a recumbent  portion  in  contact  with  the  basal  lamina  and  then  bend  to  become 
perpendicular  to  the  base.  Autozooecial  apertures  are  rounded  with  an  average  diameter  of  0-22  mm  by 
016  mm.  Small  polygonal  exilazooecia  occur  between  the  autozooecia  (average  maximum  diameter  is 
0 08  mm).  Hyaline  lunaria  are  observed  in  the  autozooecia  in  shallow  tangential  section.  Rare  basal 
diaphragms  have  been  recognized. 

Bifurcating  and  anastomosing  tunnel  structures  are  common,  positioned  a distance  from  the  edge  of  the 
colony  (2  mm  in  PD9885).  The  tunnels  are  on  average  0-21  mm  wide  and  extend  for  111  mm  in  length  between 
bifurcations.  At  the  site  of  bifurcation  a crescent-shaped  exilazooecium  occurs.  The  tunnels  are  divided 
internally  by  thin-walled  barriers. 

Communication  pores  are  present  in  the  exozone,  commonly  two,  but  up  to  three,  pores  per  autozooecium. 
They  are  situated  on  either  side  of  the  autozooecial  aperture,  occasionally  with  one  in  between. 

Microstructure  is  hard  to  distinguish  but  appears  to  be  laminar. 

Remarks.  The  species  Lichenalia  concentrica  Hall  has  been  recognized  in  North  America  from  the 
Rochester  Shale  (middle  Silurian),  New  York  State  and  Ontario  (Hall  1852;  Bassler  1906;  Hewitt 
and  Cuffey  1985),  and  in  the  USSR  from  the  Borkholm  Limestone,  Borkholm,  Estonia  (Bassler 
1911).  Lichenalia  cf.  concentrica , described  in  the  present  study,  is  very  similar  to  previous 
descriptions  of  L.  concentrica , e.g.  by  Bassler  (1906)  and  Hewitt  and  Cuffey  (1985).  The  major 
difference  is  the  presence  of  communication  pores,  which  have  not  been  recognized  previously.  This 
difference  may  be  significant  or  merely  due  to  the  exceptional  preservation  of  the  material  described 
herein  from  Dudley.  The  majority  of  examples  of  Lichenalia  described  previously  do  not  show  the 
frontal  surface  of  the  colony  as  it  adheres  to  the  rock  matrix,  and  communication  pores  may 
therefore  have  been  present  but  not  observed.  The  type  material  from  the  Rochester  Shale  (middle 
Silurian),  Lockport,  New  York  State,  USA,  needs  to  be  re-examined  in  conjunction  with  this  new 
British  material  to  establish  if  they  are  indeed  conspecific. 

Order  cyclostomata  Busk,  1852 
Family  crownoporidae  Ross,  1967 
Genus  kukersella  Toots,  1952 

Kukersella  borealis  (Bassler,  1911) 

Plate  7,  figs  7 and  8 

Description.  Colony  erect  with  narrow  subcylindrical  branches  (average  diameter  T08  mm),  arising  from  an 
encrusting  base.  Endozonal  zooecia  are  very  thin-walled  and  are  oriented  parallel  to  the  branch  growth 
direction  to  form  an  axial  bundle  which  reaches  the  colony  surface  only  at  the  distal  growth  tips.  Abundant, 
closely-spaced  (0-09  mm)  diaphragms  occur  throughout  the  length  of  the  endozonal  zooecia  and  are  deflected 
orally  at  their  junction  with  vertical  interzooecial  walls. 

Exozonal  zooecia  surround  the  axial  bundle  of  endozonal  zooecia.  They  are  thick-walled,  average  0-48  mm 
in  length  and  their  walls  contain  sparse  communication  pores  at  levels  close  to  the  colony  surface.  Occasional 
diaphragms  are  developed  at  levels  close  to  the  colony  surface.  They  are  deflected  orally  where  they  meet  the 
interzooecial  walls.  Frontal  walls  of  exozonal  zooecia  have  distal  subcircular  apertures  with  an  average 
diameter  of  015  mm  and  slight  peristomes.  Frontal  walls  are  densely  pseudoporous,  the  pseudopores  being 
variable  in  size  but  consistently  large,  on  average  0-02  mm  in  diameter.  They  are  crater-like  in  external 
morphology,  with  funnel-shaped  openings. 

The  encrusting  bases  are  composed  entirely  of  zooecia  resembling  those  of  the  exozone  in  erect  branches. 


BUTTLER:  WELSH  ORDOVICIAN  BRYOZOANS 


105 


Remarks.  A more  complete  description  of  this  species  and  a synonymy  may  be  found  in  Buttler 
(1989). 


BIOGEOGRAPHICAL  COMPARISONS 

A total  of  twelve  genera  have  been  recognized  from  the  Slade  and  Redlnll  Beds  at  Pengawse  Hill. 
One,  Pimiatoporella , has  been  described  only  from  Wales,  whilst  the  rest  are  cosmopolitan.  A wide 
generic  distribution  may  have  been  caused  by  a long-lived,  planktotrophic  larval  phase  which 
encouraged  dispersal.  This  was  suggested  for  the  Ordovician  genus  Orbipora  by  Taylor  and  Cope 
(1987).  Living  cyclostomes  have  non-planktotrophic  larvae  but  Taylor  and  Cope  consider  that  some 
early  stenolaemates  may  have  inherited  a planktotrophic  larval  stage  from  their  inferred  ctenostome 
ancestors. 

Of  the  fifteen  species  identified  from  this  locality  seven  have  not  been  previously  recognized 
elsewhere.  Three  of  these  are  new  species  and  the  rest  are  left  in  open  nomenclature.  It  is  difficult 
to  know  whether  this  is  true  endemism  or  the  result  of  sampling  and/or  preservation.  Three  species 
have  very  wide  geographical  ranges:  Kukersella  borealis , Hallopora  elegantula  and  Lichenalia 
concentrica.  They  have  all  been  described  previously  from  both  North  America  and  Baltoscandia. 

The  Welsh  taxa  show  the  greatest  affinity  with  Baltoscandia,  sharing  six  of  the  fifteen  species.  The 
faunal  similarities  between  Baltoscandia  and  the  Anglo-Welsh  Region  have  been  examined  in  detail 
for  other  groups  (e.g.  Cocks  and  Fortey  1982;  Vannier  et  al.  1989),  although  poor  knowledge  of 
British  bryozoans  has  previously  prohibited  comparison.  The  bryozoans  support  the  hypothesis 
that  Tornquist's  Sea,  which  separated  the  two  regions  during  the  early  Ordovician,  was  no  longer 
a physical  structure  effecting  faunal  separation  in  the  late  Ordovician.  The  exact  time  of  its  closing 
is  hard  to  ascertain  but  the  similarity  in  faunas  from  the  Caradoc  onwards  suggests  that  by  the  late 
Ordovician  Tornquist's  Sea  was  nearly  if  not  actually  closed. 

North  America,  or  Laurentia,  was  separated  during  the  lower  Ordovician  from  Baltoscandia  and 
the  majority  of  the  British  Isles  by  Iapetus.  Faunal  and  structural  studies  have  examined  the  exact 
timing  of  the  closure.  Pickering  et  al.  (1988),  using  a variety  of  palaeontological,  stratigraphical, 
structural,  geophysical  and  igneous  evidence,  considered  that  by  the  end  of  the  Ordovician  Iapetus 
was  partially  closed  with  only  marine  seaways  persisting  to  the  mid-Silurian.  During  the  late 
Ordovician  Iapetus  did  not  form  an  impenetrable  barrier  to  the  bryozoans.  Four  species  (17%  of 
the  fauna)  from  Pengawse  Hill  are  also  known  from  the  early  Palaeozoic  of  North  America. 

Only  one  species  (Dekayia  cf.  crenulata)  from  Wales  is  similar  to  the  bryozoan  fauna  described 
from  the  Montagne  Noire  region  of  France.  This  region  would  have  formed  part  of  Gondwana, 
which  was  separated  from  Laurentia,  the  British  Isles  and  Baltoscandia  during  the  late  Ordovician 
by  the  Rheic  Ocean,  explaining  why  the  similarity  of  the  two  faunas  is  minimal. 

Any  biogeographical  findings  concerning  bryozoans  can  only  be  preliminary  because  of  the  poor 
knowledge  of  British  (and  European)  Ordovician  bryozoans,  especially  when  compared  with  other 
groups.  This  emphasizes  the  great  need  for  further  research  and  the  importance  of  systematic  studies 
of  British  Ordovician  bryozoans. 


Acknowledgements.  I would  like  to  thank  Dr  J.  C.  W.  Cope  and  Dr  P.  D.  Taylor  for  supervising  this  project, 
which  was  carried  out  under  the  tenure  of  a Natural  Environmental  Research  Council  Studentship.  I am 
grateful  to  Mr  F.  Cross,  Dr  D.  H.  Evans  and  Dr  S.  J.  Buttler  for  assistance  in  the  field. 


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History),  (Geology),  12,  107-135. 

— 1967.  Champlainian  Ectoprocta  (Bryozoa),  New  York  State.  Journal  of  Paleontology,  41,  632-648. 


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shrubsole,  G.  w.  1885.  Note  on  the  Glauconome  distincta  from  the  Bala  Beds  of  Glyn  Ceiriog.  Proceedings 
of  the  Chester  Society  of  Natural  Science , 3,  98-100. 

— and  vine,  G.  R.  1882a.  The  Silurian  species  of  Glauconome  and  a suggested  classification  of  Palaeozoic 
Polyzoa.  Journal  of  the  Geological  Society  of  London , 38,  245. 

- 18826.  The  Silurian  species  of  Glauconome  and  a suggested  classification  of  Palaeozoic  Polyzoa. 
Geological  Magazine , 9,  381-382. 

1884.  The  Silurian  species  of  Glauconome  and  a suggested  classification  of  Palaeozoic  Polyzoa. 
Journal  of  the  Geological  Society  of  London , 40,  329-332. 
shulga-nesterenko,  m.  i.  1955.  Kamennougol’nye  Mshanki  Russkoj  Platformy.  Trudy  Akademy  Nauk  SSSR 
Institut,  57,  1-207.  [In  Russian], 

silliman,  b.,  silliman,  b.  Jr.  and  dana,  j.  d.  1851.  New  genera  of  fossil  corals  from  the  report  of  James  Hall, 
on  the  paleontology  of  New  York.  American  Journal  of  Science  and  Arts , 2(  1 1),  398-401. 
spjeldnaes,  n.  1957.  A redescription  of  some  type  specimens  of  British  Ordovician  Bryozoa.  Geological 
Magazine , 38,  1072-1081. 

1963.  Some  silicified  Ordovician  fossils  from  South  Wales.  Palaeontology , 6,  254—263. 

— 1983.  Upper  Ordovician  bryozoans  from  Ojl  Myr,  Gotland,  Sweden.  Bulletin  of  the  Geological  Institutions 
of  the  University  of  Uppsala,  10,  1-66. 

taylor,  p.  d.  and  cope,  J.  c.  w.  1987.  A trepostome  bryozoan  from  the  Lower  Arenig  of  south  Wales: 
implications  of  the  oldest  described  bryozoan.  Geological  Magazine,  124,  367-371. 
toots,  h.  1952.  Bryozoen  des  estruschen  Kukersits.  Mitteilungen  aus  dem  geologischem  Staatsinstitut  in 
Hamburg,  21,  113-137. 

ulrich,  e.  o.  1882.  American  Paleozoic  Bryozoa.  Journal  of  the  Cincinnati  Society  of  Natural  History,  5, 
121  -175,  232-257. 

— 1 890.  Paleontology  of  Illinois.  Paleozoic  Bryozoa.  Bulletin  of  the  Geological  Survey  of  Illinois,  8,  283-688. 

— 1893.  On  the  lower  Silurian  Bryozoa  of  Minnesota.  Geology  of  Minnesota,  3,  96-322. 

— and  bassler,  r.  s.  1904.  A revision  of  the  Paleozoic  Bryozoa.  Part  II  - on  genera  and  species  of 
Trepostomata.  Smithsonian  Miscellaneous  Collections,  47,  15-55. 

utgaard,  j.  1968.  A revision  of  the  North  American  genera  of  ceramoporid  bryozoans  (Ectoprocta),  pt.  2, 
Crepipora,  Ceramoporella,  Acanthoceramoporella  and  Ceramophylla.  Journal  of  Paleontology,  42,  1444-1455. 

1973.  Mode  of  colony  growth,  autozooids,  and  polymorphism  in  the  bryozoan  order  Cystoprata. 
317-360.  In  boardman,  r.  s.,  cheetham,  a.  h.  and  Oliver,  w.  a.  Jr.  (eds).  Animal  Colonies.  Dowden, 
Hutchinson  and  Ross,  Stroudsburg,  xiii  + 603  pp. 

vannier,  j.  m.  c.,  siveter,  d.  j.  and  schallreuter,  r.  e.  l.  1989.  The  composition  and  palaeogeographical 
significance  of  the  Ordovician  ostracode  faunas  of  southern  Britain,  Baltoscandia,  and  Ibero-Armorica. 
Palaeontology , 32,  163-222. 

vine,  G.  r.  1884.  Fourth  report  of  the  Committee  appointed  for  the  purpose  of  reporting  on  fossil  Polyzoa. 
Report  of  the  British  Association  for  the  Advancement  of  Science,  1883,  161-209. 


CAROLINE  J.  BUTTLER 
Department  of  Geology 
Trinity  College 
Dublin  2,  Ireland 


Manuscript  received  25  October  1989 
Revised  manuscript  received  24  January  1990 


Present  address: 
Department  of  Geology 
National  Museum  of  Wales 
Cathays  Park 
Cardiff  CF1  3NP,  UK 


MIDDLE  ORDOVICIAN  BIVALVES  FROM  SPAIN 
AND  THEIR  PHYLETIC  AND  PALA EOGEOGR APHIC 

SIGNIFICANCE 

by  CLAUDE  BABIN  and  JUAN-CARLOS  GUTIERRE Z-M A R C O 


Abstract.  The  rich  bivalve  fauna  from  the  Middle  Ordovician  of  Spain  is  reviewed,  and  some  new  taxa 
established:  Dulcineaia  manchegana  gen.  and  sp.  nov.,  Praenucula  sharpei  sp.  nov.  and  Ekaterodonta  hesperica 
sp.  nov.  Some  palaeotaxodontids  probably  had  archaic  characters,  such  as  the  dentition  of  Ekaterodonta  and 
the  pedal  muscles  of  Myoplusia.  The  common  trend  towards  the  production  of  crenulated  teeth  among 
actinodonts  and  their  descendants  is  underlined;  Dulcineaia  is  a new  example  among  Redoniidae.  The 
comparison  with  the  crenulations  of  some  paleotaxodontids  does  not  show  any  general  constraints  governing 
the  evolution  of  microcrenulations.  Bivalve  distribution  within  the  Selenopeltis  province  is  apparently  complex 
with  some  endemics  during  the  Middle  Ordovician.  The  Spanish  faunas  were  largely  dominated  by  small 
endobenthic  shells  which  suggests  a cool-water  area. 

The  Middle  Ordovician  bivalve  molluscs  from  the  shales  of  the  Hesperian  Massif  were  described 
by  Sharpe  (1853)  from  Portugal  and  by  de  Verneuil  and  Barrande  (1856)  from  Spain.  Since  then, 
these  faunas  have  not  been  revised.  In  contrast,  other  groups,  trilobites,  graptolites,  echinoderms, 
have  provided  the  basis  of  numerous  studies  which  have  enabled  a precise  biostratigraphy  for  the 
Llanvirn  and  Llandeilo  series  to  be  established  in  the  Hesperian  Massif  (Hamman  1974,  1983; 
Hamman  el  a/.  1982;  Romano  1982;  Gutierrez-Marco  et  ah  19846;  Rabano  1984,  1988; 
Gutierrez-Marco  1986).  The  only  indications  of  bivalves  are  a list  of  species  by  Gutierrez-Marco 
et  al.  (1984 h),  a figure  of  Redonia  cf.  deshayesi  from  the  Ossa  Morena  Zone  (Gutierrez-Marco  et  ah, 
1984a)  and  the  description  of  a new  cycloconchid  (Babin  and  Gutierrez-Marco  1985).  Similar 
faunas  have  been  the  subject  of  detailed  researches  in  the  Armorican  Massif  (Babin  1966,  1977; 
Bradshaw  1970).  Increasing  interest  has  been  given  to  other  Lower  and  Middle  Ordovician  bivalve 
faunas  elsewhere  (Pojeta  1971;  Morris  and  Fortey  1976;  Pojeta  and  Gilbert-Tomlinson  1977; 
Pojeta  1978;  Morris  1978,  1980;  Babin  1981,  1982;  Babin  et  ah  1982).  Thus,  it  is  appropriate  to 
revise  the  systematics  of  these  numerous  and  diverse  molluscs  in  a modern  framework,  and  to 
discuss  their  phyletic  and  palaeogeographical  significance. 

This  paper  is  a contribution  to  Project  ID-456  ('Biostratigraphy  and  palaeoecology  of  the  Lower 
Paleozoic  rocks  of  SW  Hesperian  Massif1)  of  Comision  Acesora  de  Investigacion  Cientifica  y 
Tecnica  Consejo  Superior  de  Investigaciones  Cienti'ficas,  1985-1988  programming. 


GEOLOGICAL  SETTING  OF  SPANISH  MIDDLE  ORDOVICIAN  BIVALVES 

We  have  studied  2400  bivalve  samples  from  87  localities  widely  distributed  along  the  Spanish  part  of 
the  Hesperian  Massif.  This  massif  comprises  a large  area  of  the  Iberian  Peninsula  and  contains  the 
most  extensive  outcrops  of  Ordovician  rocks  known  in  the  European  Hercynian  fold  belt.  Text- 
figure  1 shows  the  approximate  position  of  the  fossil  localities.  Their  detailed  locations  have  been 
deposited  with  the  British  Library,  Boston  Spa,  Yorkshire,  UK,  as  Supplementary  Publication  No. 
SUP  14041  [6  pages]. 

The  bivalve  faunas  come  from  several  formations,  composed  mainly  of  shales  with  scarce 
sandstones,  the  latter  predominating  only  in  the  youngest  beds  of  the  succession.  They  can  all  be 
assigned  to  the  'Tristani  Beds’  of  early  authors,  which  have  been  divided  into  a number  of 


I Palaeontology,  Vol.  34,  Part  1,  1991,  pp.  109-147,  7 pls.| 


© The  Palaeontological  Association 


110 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  1.  Map  showing  outcrops  of  Ordovician  rocks  in  the  Iberian  Peninsula  in  solid  black  with  the  studied 
Lower  Ordovician  bivalve  localities.  Symbols:  a,  Precambrian  and  Palaeozoic  rocks;  b.  Ordovician  outcrops; 
c,  post-Palaeozoic  cover,  a-e,  structural  zones  of  the  Hesperian  Massif : a,  Cantabrian  zone;  b,  West-Asturian- 
Leonese  zone  (and  its  southern  extension  in  the  Iberian  Cordillera);  c,  Central-Iberian  zone;  d,  Ossa-Morena 
zone;  e,  South-Portuguese  zone.  Fossil  localities:  1,  ‘Sueve’;  2,  Fonrbuena-Herrera  (FB,  LU,  HERR);  3, 
Calamocha  (PO);  4,  Aragoncillo  (CR,  PS);  5,  El  Pobo  (PD);  6,  Geo  de  Albarracin  (GA);  7,  Truchas  (TR); 
8,  El  Atazar  (AT);  9,  La  Bastida  (LB);  10,  Alia-Navalpino  (PSV,  HM,  RA);  11,  Navas  de  Estena-Retuerta 
(NE,  RE);  12,  Ventas  (VPA);  13,  Benazaire-Puebla  de  Don  Rodrigo  (Hd,  PR,  PI);  14,  Herrera  del  Duque 
(HD);  15,  Pozuelos-Corral  de  Calatrava  (PZ,  CO);  16,  Sierra  de  San  Pedro  (SVA,  PC);  17,  Santa  Eufemia 
(SEU);  18,  Almaden  (AC,  AM,  CHI,  GS);  19,  Fuencaliente  (FU);  20,  Calzada-Viso  del  Marques  (CC,  VM); 

21,  Sierra  Morena  oriental  (ALAM);  22,  Cazalla  de  la  Sierra  (CS). 


formations  as  summarized  and  correlated  by  Hammann  et  al.  (1982)  and  Gutierrez-Marco  et  al. 
(1984a,  in  press). 

Most  of  the  bivalves  are  preserved  as  internal/external  moulds  in  shales,  silty  nodules  and  the 
sandstones;  rare  casts  of  specimens  with  conjoined  valves  replaced  by  hematitic  or  silty  materials 
have  seldom  been  found. 

Text-figure  2 shows  the  stratigraphic  distribution  of  the  species  based  on  accompanying  fossils  of 
biostratigraphical  value  (graptolites,  trilobites,  brachiopods  and  microfossils).  Nevertheless,  it  has 
been  shown  elsewhere  that  there  is  difficulty  in  correlating  the  Spanish  Ordovician  with  the  British 


BABIN  and  GUTIERREZ-M ARCO:  ORDOVICIAN  BIVALVES 


LLANVIRN 

LLANDEILO 

Lower 

Upper 

Lower 

Upper 

1 Ctenodonta  cf.  escosurae  (SHARPE) 

2 Praenucula  costae  (SHARPE) 

3 Praenucula  sharpei  n.sp. 

4 Cardiolaria  beirensis  (SHARPE) 

5 Ekaterodonta  hesperica  n.sp. 

6 Myoplusia  bilunata  perdentata  (B  ARRANDE) 

7 Cadomia  britannica  (BABIN) 

8 Goniophora  ( Cosmogoniophora ) sp. 

9 Modiolopsis  ? elegantulus  SHARPE 

10  Cyrtodontula  sp. 

1 1 Glyptarca  ? lusitanica  (SELARPE) 

12  Ananterodonta  oretanica  BABIN  & GUTIERREZ- 

13  Babinkaprima  B ARRANDE  MARCO 

14  Coxiconcha  britannica  (ROUAULT) 

15  Redonia  deshayesi  ROUAULT 

16  Dulcineaia  manchega  n.gen.,  n.sp. 

— 

- 

— 

— 

text-fig.  2.  Stratigraphic  distribution  of  Spanish  Middle  Ordovician  bivalve  species. 


stratotypes  of  the  Llandeilo  Series.  For  this  reason,  some  authors  adopt  the  Bohemian  Dobrotiva 
Series  (Havlicek  and  Marek  1973),  with  which  the  Ordovician  sequences  of  the  Southern 
Gondwanan  platform  (‘Mediterranean  area’)  are  also  easier  to  correlate.  The  Dobrotiva  Epoch  is, 
however,  a possible  equivalent  of  the  global  standard  Teretiusculus  Zone.  Thus,  with  reservation, 
we  use  the  Llandeilo  Series  in  spite  of  controversy  (Whittington  el  a/.  1984). 


SYSTEMATIC  PALAEONTOLOGY 

The  classification  used  by  Pojeta  (1987)  is  adopted  here.  The  morphological  indexes  used  in  some 
descriptions  are  those  defined  by  Babin  (1966,  p.  28).  If  not  otherwise  cited,  figured  and  described 
specimens  are  in  the  Department  of  Palaeontology,  Complutense  University  of  Madrid,  Spain. 
Complementary  material  is  housed  in  the  Laboratory  of  Palaeontology,  University  of  Brest  (LPB), 
in  the  Universite  Claude  Bernard  - Lyon  I (FSL),  in  the  British  Museum  of  Natural  Flistory, 
London  (BMNH)  and  in  the  Narodni  Museum  of  Prague. 


Class  bivalvia  Linnaeus,  1758 
Subclass  palaeotaxodonta  Korobkov,  1954 
Order  nuculoidea  Dali,  1889 
Superfamily  ctenodontacea  Wohrmann,  1893 
Family  ctenodontidae  Wohrmann,  1893 
Genus  ctenodonta  Salter,  1852 

Type  species.  Tellinomya  nasuta  Hall,  1847,  by  subsequent  designation  of  Salter  (1859,  p.  34). 
Diagnosis.  Nuculaniform  ctenodontids  lacking  prominent  concentric  ornament. 


cf.  Ctenodonta  escosurae  (Sharpe,  1853) 
Plate  1,  figs  1-4 

cf.  1853  Leda  escosurae  Sharpe,  p.  151,  pi.  9,  fig.  8. 


112 


PALAEONTOLOGY,  VOLUME  34 


Material.  Two  internal  moulds  (one  right  valve  and  one  left  valve),  CR  II  2161/OR. 

Locality  and  stratigraphical  range.  Basal  shales  of  La  Venta  Formation,  Aragoncillo  Massif  (Iberian  Cordillera, 
Castilian  Branch);  lowermost  Llanvirn. 

Description  and  discussion.  Small  shell  (respectively  13  and  10  5 mm  long)  with  a weak  beak  situated  at  the 
anterior  third.  Anterior  margin  and  ventral  side  convex;  maximum  height  located  exactly  behind  the  umbo. 
Posterior  end  gently  elongate  and  rounded;  a very  faint  depression  on  the  posterior  part  of  the  shell  produces 
a discrete  inflexion  of  the  ventral  margin  between  the  posterior  fourth  and  fifth  parts.  Characters  of  the  hinge 
plate  unknown.  Anterior  adductor  muscle  scar  posteriorly  fringed  by  a small  high  and  broad  septum.  Posterior 
adductor  scar  poorly  visible  and  anteriorly  limited  by  a weak  undulation  of  the  valve. 

Sharpe’s  material  of  Leda  escosurae  is  BMNH  PI.  4106  (internal  mould  of  a bivalve  specimen,  figured  by 
Sharpe,  pi.  9,  fig.  8,  which  must  be  considered  as  lectotype;  figured  here,  PI.  1,  figs  1 and  2)  and  BMNH  PI. 
4138  (internal  mould  of  a right  valve,  paralectotype). 

Sharpe’s  types  are  nuculaniform  with  their  elongate  posterior  end,  but  the  dentition,  with  numerous  chevron- 
shaped teeth,  has  no  resilifer.  Thus  these  forms  must  be  referred  to  Ctenodonta  as  used  since  McAlester  (1968) 
and  Pojeta  (1971)  for  Nuculoida  without  a resilifer  and  with  a rostrate  end.  Our  specimens  have  an  outline 
similar  enough  to  that  of  Ctenodonta  escosurae , but  their  dentition  is  not  preserved  and  we  must  leave  them 
in  open  nomenclature.  Barrande  ( 1 88 1 , pis  269  and  270)  figured  several  ‘ species  ’ of  ‘ Leda  ’ from  the  Ordovician 
of  Bohemia,  but  they  belong  to  other  genera  and  are  different  from  C.  escosurae  (Pfab  1934).  There  are  many 
elongate  shells  in  the  Ordovician,  and  they  probably  belong  to  different  families  or  even  different  orders  (e.g. 
Thoralia  Morris,  1980  = Miquelana  Babin,  1982,  junior  synonym  from  the  Arenig  of  the  Montagne  Noire); 
unfortunately,  the  material  is  often  poorly  preserved. 

Superfamily  nuculacea  Gray,  1824 
Family  praenuculidae  Pfab,  1934 

Remarks.  Since  the  revision  by  McAlester  ( 1968)  of  the  type  material,  efforts  have  been  made  to  homogenize 
the  generic  designations  of  palaeotaxodontids  from  the  Lower  Palaeozoic.  However,  some  confusion  persists 
because  these  small  bivalves  are  numerous,  variable,  sometimes  polymorphous  and  are  often  badly  preserved 
or  distorted.  Among  the  praenuculids,  Tunnicliff  (1982)  has  discussed  the  difficult  distinctions  between 
Praenucula , Praeleda , and  Deceptrix.  We  shall  try  to  apply  this  author’s  criteria  to  distinguish  Praenucula 
(anterior  and  posterior  teeth  subsimilar  in  size  and  number;  umbo  lying  in  the  posterior  half)  and  Deceptrix 
( = Praeleda ) (posterior  teeth  smaller  and  more  numerous  than  the  anterior;  umbo  lying  in  the  anterior  half; 
adductor  muscle  scars  larger  and  more  ventral  than  in  Praenucula.) 

Genus  praenucula  Pfab,  1934 

Type  species.  Praenucula  dispar  expansa  Pfab,  1934  (from  the  Sarka  Formation,  Llanvirn  of  Bohemia)  by 
original  designation  of  Pfab,  1934  (pp.  234-235).  See  discussion  under  Praenuculidae  above. 


EXPLANATION  OF  PLATE  1 

Figs  1 and  2.  Ctenodonta  escosurae  (Sharpe,  1853).  Lectotype  (BMNH,  PI.  4106),  Middle  Ordovician,  Portela 
de  Loredo,  Serra  de  Bussaco  (Portugal).  1,  right  view,  2,  cardinal  view.  Both  x4. 

Figs  3 and  4,  cf.  Ctenodonta  escosurae.  Aragoncillo  Massif  (Iberian  Cordillera),  basal  part  of  La  Venta 
Formation,  lowermost  Llanvirn.  3,  internal  mould  of  a right  valve  (CR-II  2 161 /OR),  x 4.  4,  internal  mould 
of  a left  valve  (CR-II  2 161/OR),  x4. 

Figs  5-9.  Praenucula  costae  (Sharpe,  1853).  5-8,  Calzada  de  Calatrava  (Ciudad  Real),  middle  part  of  the 
Guindo  Shales,  late  Lower  Llandeilo;  5,  internal  mould  of  a right  valve  showing  numerous  borings  on  the 
ventral  part  (CC-I  2 169/OR),  x4;  6,  detail  of  the  postero-unrbonal  part  of  an  internal  mould  of  a right 
valve,  the  muscle  scars  (posterior  adductor  and  pedal  accessory)  show  growth  lines;  some  borings  are  present 
(CC-I  2 166/OR),  x 8;  7,  internal  mould  of  a left  valve  (CC-I  2 168bis/OR),  x 4.  8,  latex  replica  of  the  same, 
x4.  9,  Ventas  con  Penas  Aguilera  (Toledo),  lower  part  of  the  Navas  de  Estena  Shales,  Lower  Llanvirn; 
internal  mould  of  the  continuous  dentition  of  the  right  valve  of  a young  specimen  (VPA  2 171/OR),  x 8. 


PLATE  1 


BABIN  and  GUTIERREZ-MARCO,  Middle  Ordovician  Bivalvia 


114 


PALAEONTOLOGY,  VOLUME  34 


Praenucula  costae  (Sharpe,  1853) 

Plate  1,  figs  5-9 

1853  Nucula  costae  Sharpe,  p.  149,  pi.  9,  fig.  4. 

1970  Praeleda  costae  (Sharpe),  Bradshaw,  p.  630,  text-figs  7-10  (synonymy). 

Material.  About  320  internal  moulds. 

Localities  and  stratigraphical  range.  Lower  Llanvirn  to  Upper  Llandeilo  (muddy  and  sandy  facies)  of  the 
Cantabrian  zone  (Sueve),  West  Asturian-leonese  zone  (TR-III),  Iberian  Cordillera  (FB-IV,  GA-II,  HERR-I, 
PD-I,  PO-I),  and  34  localities  in  the  Central-Iberian  zone  (AC-II,  ALAM-III,  Albadalejo,  CC-I  & II,  CHI-IV, 
CO-XII  and  XIV-XVI,  HD-IV-VI,  HM-II  and  IV,  La  Carcel,  La  Vibora,  NE-IV  & VII,  PI-IV,  PR-IX,  PSV- 
III-V,  PZ-III,  RA-I,  IA,  II,  IVB  and  VI,  SEU-II,  SP-IV,  VM-I,  VPA).  This  species  is  particularly  common  in 
RA-I,  CC-I,  VPA,  PSV-III/IV  and  La  Vibora. 

Description.  Shell  small,  convex,  with  a strong  umbo  lying  in  the  posterior  half  and  prominent  convex  cardinal 
margin.  Ventral  margin  also  convex,  the  posterior  side  more  or  less  rounded  and  the  anterior  side  truncate.  In 
juvenile  forms  the  adductor  scars  are  poorly  impressed,  but  in  adults  they  are  more  marked.  Anterior  adductor 
scar  large,  oval,  parallel  with  the  anterior  margin  and  strongly  impressed  on  its  posterior  side.  Posterior  scar 
smaller  and  round.  Two  pedal  accessory  scars  always  present;  one  adjacent  to  the  anterior  adductor  scar  on 
its  dorsal  side;  the  other  is  elongate  and  situated  half-way  along  the  posterior  hinge  plate.  One  specimen  (CC 
2166/OC)  shows  growth  lines  on  this  scar  and  on  the  posterior  adductor  scar  (PI.  1,  fig.  6).  Specimen  RA-I 
2167/OR  has  other  scars  near  the  extremity  of  the  umbo  (Text-fig.  3). 


1 mm 

I I 


text-fig.  3.  Praenucula  costae  (Sharpe,  1853).  Umbonal  view  of  an  internal  mould  of  a left  valve  (RA-I  2 
167/OR)  showing  accessory  muscle  scars:  two  small  anterior  scars  (medium  arrows),  one  umbonal  scar  (large 
arrow)  and  four  very  small  posterior  scars  (between  the  fine  arrows). 


The  dentition  comprises  a varying  number  of  teeth  according  to  the  size  of  the  shell.  The  two  series,  anterior 
and  posterior,  are  arranged  without  disruption  beneath  the  umbo  (PI.  1,  fig.  8)  and  so  the  teeth  are  difficult 
to  count. 

Length  of  shell  (mm)  3,  3-5,  6-5,  7-5,  7-8,  8-5,  10,  10,  10-5,  12,  12-5,  13,  13-5,  14,  15,  16,  16,  17,  19 
Number  of  posterior  teeth  6,  7,  6,  9,  6,  10,  8,  13,  10,  15,  14,  14,  1 1,  13,  14,  16,  21.  15,  17 
Number  of  anterior  teeth  6,  5,  6,  9,  6,  7,  7,  1 1,  9,  10,  12,  10,  9,  13,  13,  12,  10,  12,  13 

Several  specimens  have  more  numerous  posterior  teeth,  a character  also  indicated  by  Bradshaw,  and 
considered  by  Tunnicliff  as  a criterion  for  the  genus  Deceptrix.  However,  the  umbo  is  in  the  posterior  half,  a 
character  of  Praenucula. 


BABIN  and  GUTIERREZ- MARCO:  ORDOVICIAN  BIVALVES 


115 


The  anterior  teeth  are  convex,  beneath  the  umbo  they  are  orthomorph,  and  on  the  posterior  hinge  plate  they 
are  convexo-concave  and  concave.  A single  specimen  (RA-I  2167/OR)  shows  an  inconspicuous  disruption 
between  the  two  series. 

Discussion.  Bradshaw  (1970)  studied,  using  material  from  the  Armorican  Ordovician,  the  discrimination  of  the 
two  Sharpe  species,  costae  and  ciae.  P.  costae  shows  ‘two  series  of  teeth  arranged  at  an  angle  to  each  other’, 
also  figured  by  Babin  ( 1966,  figs  27  and  28 ; pi.  2,  figs  6.  12,  1 3)  under  the  designation  Palaeoneilo  ctenodontoides 
(this  generic  conception  of  Palaeoneilo , that  of  Douville  [1912,  p.  38],  became  outmoded  after  McAlester’s 
revision  in  1968).  One  of  us  (C.B.)  observed  that  Sharpe’s  type  of  P.  costae  (BMNH,  PI.  4100)  shows  this 
disruption.  It  is  only  seen  in  one  Spanish  specimen  (see  above);  nevertheless  the  distribution  of  the  teeth,  i.e. 
more  numerous  in  the  posterior  hinge  plate,  is  close  to  P.  costae.  Moreover,  Bradshaw  (1970)  wrote  ” P.  costae 
is  particularly  interesting  as  it  is  the  more  variable  of  the  two  species  and  sometimes  exhibits  a dental  plate 
similar  to  that  of  P.  ciae” . She  also  figured  (text-fig.  10)  an  internal  mould  of  P.  costae  without  the  discordance 
between  the  two  series  of  teeth. 

Another  character  used  by  Bradshaw  to  distinguish  between  the  two  species  is  the  pattern  of  the  accessory 
muscle  scars.  The  umbonal  scars  are  usually  preserved  and  well  marked  in  the  Armorican  material  (Babin  1966, 
fig.  26;  Bradshaw  1970,  figs  8,  9,  12),  but  they  are  not  present  or  preserved  in  the  Spanish  material.  On  the  other 
hand,  the  position  of  the  accessory  scar  lying  half-way  along  the  posterior  part  of  the  hinge  plate  is  always  seen, 
which,  according  to  Bradshaw,  is  a feature  of  P.  costae.  So  it  seems  justified  to  consider  P.  costae  as  a 
polymorphic  species  and  to  place  the  Spanish  specimens  within  it.  The  variations  affecting  the  dentition  and 
the  accessory  scars  are  thus  considered  dependent  on  inlraspecific  variability  between  geographically  isolated 
populations. 

There  are  other  related  species  of  P.  costae  and  P.  ciae',  for  example,  ‘ Ctenodonta'  nuda  from  the  Swedish 
Middle  Ordovician  (Soot-Ryen  and  Soot-Ryen  1960,  pi.  I,  fig.  1)  has  a narrower  posterior  end.  It  is  possible 
that  some  of  the  specimens  from  Bohemia,  illustrated  by  Barrande  (1881,  pi  269)  as  Leda  bohemica , are  closely 
allied  to,  if  not  conspecific  with,  P.  costae  (Pfab  1934,  p.  223,  excluded  from  C.  bohemica  several  of  Barrande’s 
specimens).  Tunnicliff  (1982,  p.  50)  has  also  compared  P.  praetermissa  from  the  Irish  Ashgill  with  P.  costae  and 
P.  ciae.  Thus,  this  palaeotaxodontid  morphology  was  very  frequent  during  the  Middle  and  Upper  Ordovician. 

Praenucula  sharpei  n.  sp. 

Plate  2,  figs  1-6 

19846  Deceptrix  n.  sp.  Martin  in  Gutierrez-Marco  et  a/.,  p.  302. 

Holotype.  Internal  mould  of  a right  valve  showing  the  dentition,  RA-I  2148/OR. 

Type  locality  and  horizon.  7500  m ESE  from  Horcajo  de  los  Montes  (Ciudad  Real),  in  the  El  Calvario  hillock 
peak  (646  m),  N of  Los  Rasos  de  Navalaceite  hamlet.  Reddish  shales  with  coquinas  from  the  upper  half  of  the 
Navatrasierra  Shales;  early  Upper  Llanvirn  ( Cacemia  beds). 

Derivation  of  name.  Dedicated  to  Daniel  Sharp  who  was  the  first  describer  of  Ordovician  bivalves  from  the 
Iberian  peninsula. 

Paratypes.  RA-I  2 146/OR,  2 147/OR,  2 149/OR,  2 183/OR;  NE-IV  2 189/OR  (two  specimens);  PZ-III  2 
187/OR,  2 188/OR  (two  specimens);  RE-IX  2 186/OR;  SP-IV  2 184/OR;  VPA-2  144/OR,  2 145/OR,  2 
185/OR  (ten  specimens). 

Diagnosis.  Small  species  of  Praenucula , convex  and  high,  with  few  teeth  distributed  almost  equally 
between  the  two  parts  of  the  hinge  plate.  Adductor  muscle  scars  not  very  extended  and  badly 
impressed. 

Description  and  discussion.  Shells  are  generally  small  (of  32  measured  specimens,  the  mean  length  is  8-6  mm, 
the  range  4-7-1 5 5 mm).  Anterior  region  is  a little  elongated  and  the  posterior  one  rounded.  The  umbones  lie 
in  the  posterior  half  but  near  the  middle  of  the  length  (mean  of  the  umbonal  index:  56  04).  Shell  is  high  (mean 
of  the  lengthening  index  [C.  Babin,  1966]:  75  57).  The  cardinal  side  is  gently  arched.  Adductor  scars  discrete, 
oval,  situated  in  the  anterior  and  posterior  angles;  a small  pedal  posterior  scar  occurs  between  the  posterior 
adductor  and  the  hinge  plate,  and  an  anterior  scar  adjacent  to  the  upper  point  of  the  anterior  adductor  muscle. 


116 


PALAEONTOLOGY,  VOLUME  34 


Dentition  usually  limited  to  the  middle  part  of  the  cardinal  line  with  few  teeth  (generally  about  12,  ranging 
from  7 for  a shell  5 mm  long  to  28  for  a shell  15-5  mm  long).  The  teeth  are  nearly  similar  in  size  (the  posterior 
ones  are  a little  smaller  in  the  largest  specimens). 

This  species  differs  from  all  those  described  in  the  literature  in  its  shape  and  short  dentition,  and  is  known 
only  from  Spain. 


Genus  cardiolaria  Munier-Chalmas,  1876 

Type  species.  By  original  designation,  Cardiolaria  barrandei  Munier-Chalmas,  1876,  p.  107,  from  the  Upper 
Ordovician  of  the  Armorican  Massif. 

From  the  specimens  of  the  type-species  he  could  examine,  McAlester  wrote  (1968)  ‘the  dentition  immediately 
below  the  umbo  is  not  preserved’.  One  of  us  (C.B.)  has  found  in  the  collections  of  the  University  of  Lille  some 
specimens  from  the  type-locality  (la  Bouexiere)  and  one  of  them  shows  an  edentulous  space  beneath  the  umbo, 
between  the  two  series  of  teeth.  This  shows  it  to  be  attributable  to  the  genus  Cardiolaria. 


Cardiolaria  beirensis  (Sharpe,  1853) 

Plate  3,  figs  4-7 

1853  Nucula  beirensis  Sharpe,  p.  150,  pi.  9,  figs  11  and  12. 

1918  Nucula  beirensis  Sharpe,  Born,  p.  337. 

1970  Cardiolaria  beirensis  (Sharpe),  Bradshaw,  p.  624,  figs  1-4  (see  for  synonymy). 

1978  Cardiolaria  beirensis  (Sharpe),  Pojeta,  pi.  2,  fig.  15. 

Material.  About  180  internal  moulds.  The  species  is  common  from  FB-IV,  NE-VII,  RA-I,  RE-VI  and  La 
Vibora. 

Localities  and  stratigraphical  range.  Late  Lower  Llanvirn-Upper  Llandeilo,  relatively  scarce  in  shales  but  well 
represented  in  sandstone  facies.  The  studied  samples  come  from  the  West  Asturian-leonese  zone  (loc.  TR-III, 
Iberian  Cordillera  (FB-IV,  GA-II)  and  the  Central-Iberian  zone  (ALAM-IV,  CHI-IV-V,  CO-XII  and  XIIIA, 
FU-IX,  HD-IV  and  VI,  La  Carcel,  La  Vibora,  NE-VII,  PI-III  and  IV,  PSV-III  and  V,  RA-I,  RE-VI,  SVA-II). 

Description  and  discussion.  Shell  outline  rounded  and  moderately  convex,  on  the  internal  moulds  with  a strong 
prosogyrous  beak.  Anterior  adductor  muscle  scar  fringed  on  its  internal  margin  by  a strong  myophoric 
buttress ; posterior  adductor  scar  little  impressed  (the  accessory  scars  are  not  visible  except  for  an  anterior  pedal 
scar  adjacent  to  the  anterior  adductor  scar).  Dentition  comprising  five  or  six  anterior  teeth  and  15  to  20  small 
posterior  teeth.  The  two  series  are  discordant  and  separated  by  an  edentulous  space  below  the  umbo  (PI.  3,  figs 
4 and  5)  though  Bradshaw  (1970)  noted  that  juvenile  specimens  have  a continuous  dentition.  We  have  observed 
two  very  young  specimens  (FSL  550  094  and  FSL  550  095)  in  the  Armorican  material  with  a length  of  2 mm 
and  4-2  mm  respectively;  their  weak  adductor  scars  and  dentition  are  interesting  ontogenetically  (Text-fig.  4). 

It  is  undoubtedly  material  of  this  species  from  Almaden  that  de  Verneuil  and  Barrande  (1856)  determined  as 
Nucula  hopensacki.  Douville  (1912,  p.  439)  drew  the  hinge  area,  with  a wrong  age  attribution  to  the  Cambrian; 
his  original  material  appears  to  have  been  lost. 

We  also  consider  that  tour  small  specimens  (PI.  3,  fig.  6,  7)  from  locality  RA-I  2 179/OR  to  RA-I  2 181/OR 
are  possible  juvenile  forms  of  C.  beirensis.  Their  lengths  are  6-5  mm,  6-5  mm,  9 mm,  and  10-5  mm.  The  hinges 
exhibit  a continuous  series  of  22  to  25  posterior  and  umbonal  teeth  (these  latter  very  small)  and  four  or  five 


EXPLANATION  OF  PLATE  2 

Figs  1-6.  Praenucula  sharpei  n.  sp.  1,  right  view  of  an  internal  bivalve  mould  (VPA  2 144/OR),  Ventas  con  Pena 
Aguilera  (Toledo),  lower  part  of  the  Navas  de  Estena  Shales,  Lower  Llanvirn,  x 5.  2 and  3,  paratypes, 
Navalpino  (Ciudad  Real),  upper  half  of  the  Navatrasierra  Shales,  early  Upper  Llanvirn;  2,  internal  mould 
of  a right  valve  (RA-I  2 146/OR),  x 8;  3,  internal  mould  of  a left  valve  (RA-I  2 149/OR),  x 8.  4,  internal 
mould  of  a left  valve  from  San  Pablo  de  los  Montes  (Toledo),  Lower  Llanvirn  (SP-IV  2 184/OR),  x8.  5, 
holotype,  same  locality  as  paratypes,  internal  mould  of  a right  valve  (RA-I  2 148/OR),  x 8.  6,  internal  mould 
of  a left  valve  from  Venta  con  Pena  Aguilera  (Toledo),  Lower  Llanvirn,  x 5. 


PLATE  2 


BABIN  and  GUTIERREZ-MARCO,  Praenucula  sharpei  n.sp. 


118 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  4.  Cardiolaria  beirensis  (Sharpe,  1853).  Internal  mould  of  the  right 
valve  of  very  young  specimen  (FSL  550  094)  from  the  Armorican  Massif.  The 
beak  is  broken  and  the  dentition  appears  continuous. 


1 mm 

i 


anterior  teeth  which  are  stronger.  A very  similar  arrangement  was  figured  by  Bradshaw  (1970,  fig.  1).  However, 
the  Spanish  specimens  have  peculiar  muscular  impressions.  The  adductor  scars  are  well  developed  and  there 
is  a strong  anterior  myophoric  plate,  but  the  accessory  muscle  scars  are  deeply  impressed  and  numerous.  There 
is  a prominent  anterior  pedal  scar  adjacent  to  the  posterior  adductor;  these  pedal  scars  are  elongated 
perpendicular  to  the  cardinal  margin.  There  are  three  other  accessory  scars,  with  one  on  the  posterior  slope 
of  the  umbonal  region  and  the  others  in  the  median  region  of  the  valve  (PI.  3,  fig.  6,  7).  These  specimens  were 
determined  as  Tancrediopsis  ezquerrae  (Sharpe)  by  Gutierrez- Marco  et  al.  (1984fi),  but  they  do  not  have  the 
adductor  scars  of  that  species  which  also  possesses  larger  and  fewer  posterior  teeth.  We  also  note  that  T. 
ezquerrae,  described  from  Portugal  and  common  in  the  Armorican  Massif,  is  absent  from  the  observed  Spanish 
material  (another  bad  specimen  [RE-VI  2 214/OR]  may  belong  to  the  genus  Tancrediopsis  but  not  to  the 
species  T.  ezquerrae).  In  these  small  specimens  of  C.  beirensis  the  partition  beneath  the  umbo  of  the  two  series 
of  teeth  appears  late  during  ontogeny  with  later  resorption;  see  also  Bradshaw  (1970).  In  some  forms,  the 
accessory  musculature  is  reduced  during  ontogeny. 

Family  tironuculidae  Babin,  1982 
Genus  ekaterodonta  Babin,  1982 

Type  species.  By  original  designation,  Ekaterodonta  courtessolei  Babin,  1982,  p.  38,  from  the  Arenig  of  the 
Montagne  Noire  (South  of  France). 


Ekaterodonta  hesperica  n.  sp. 

Plate  3,  figs  1-3 

Holotype.  Internal  mould  of  a right  valve  showing  the  dentition,  CR-II  2 152/OR. 


EXPLANATION  OF  PLATE  3 

Figs  1-3.  Ekaterodonta  hesperica  n.  sp.  Aragoncillo  Massif  (Iberian  Cordillera),  basal  part  of  La  Venta 
Formation,  lowermost  Llanvirn.  1,  holotype,  internal  mould  of  a right  valve  showing  the  dentition  (CR-II 
2 152/OR),  x 10.  2,  paratype,  internal  mould  of  a left  valve  (CR-II  2 154/OR),  x 6.  3,  paratype,  internal 
mould  of  a right  valve  (CR-II  2 153/OR),  x 6. 

Figs  4-7.  Cardiolaria  beirensis  (Sharpe,  1853);  4 and  5,  La  Vibora,  ? Upper  Llandeilo,  latex  replica  of  two  right 
valves  showing  the  discordant  series  of  teeth  (FSL  550  109,  FSL  550  110,  x 6.  6 and  7,  Navalpino  (Ciudad 
Real),  upper  half  of  the  Navatrasierra  Shales,  early  Upper  Llanvirn ; 6,  internal  mould  of  a left  valve  showing 
accessory  muscle  scars  (RA-I  2 179/OR),  x8.5;  7,  internal  mould  of  a right  valve  with  accessory  scars 
(RA-I  2 181/OR),  x 10. 


PLATE  3 


BABIN  and  GUTIERREZ-MARCO,  Middle  Ordovician  Bivalvia 


120 


PALAEONTOLOGY,  VOLUME  34 


Type  locality  and  horizon.  2300  m N of  Aragoncillo  village,  and  900  m WNW  of  Aragoncillo  mountain 
(1518  m),  in  the  talus  of  the  first  track  to  the  Canaleja  spring.  Dark  shales  of  the  basal  part  of  La  Venta 
Formation;  earliest  Lower  Llanvirn. 

Derivation  of  name.  After  the  Hesperian  Massif,  where  most  of  the  Ordovician  outcrops  in  the  Iberian 
Peninsula  are  situated. 

Paratypes.  Internal  moulds  CR-II  2 153/OR,  CR-II  2 154/OR,  CR-II  2 155/OR  and  CR-II  2 156/OR  (6 
specimens). 

Diagnosis.  Shell  small,  rounded  and  smooth,  with  anterior  beak;  anterior  adductor  muscle  scar 
small,  rounded,  faintly  impressed;  posterior  one  is  indistinct;  dentition  has  two  short  anterior 
pseudolateral  teeth,  some  small  orthomorphic  teeth  beneath  the  umbo  and,  on  the  posterior  hinge 
plate,  some  small  chevron-shaped  teeth  and  a large  lamellar  tooth. 

Description  and  discussion.  The  shell  is  small  (length  range  from  6 5 to  1 1 mm)  and  high  (average  lengthening 
index  84-80  based  on  9 specimens) ; beak  is  curved  and  anterior  (average  umbonal  index  26-57) ; outline  rounded 
anteriorly  and  ventrally  with  a slightly  truncate  posterior  end.  The  dentition  is  only  complete  on  the  holotype; 
its  poor  preservation  and  fragility  do  not  allow  a cast  to  be  made.  It  comprises  two  short  lamellar  anterior  teeth 
perpendicular  to  the  anterior  margin  of  the  hinge  plate  and  a posterior  pseudolateral  tooth ; the  latter  possibly 
corresponds  to  the  extension  of  the  upper  arm  of  an  underumbonal  tooth  and  surmounts  the  8 or  9 more 
posterior  teeth  of  the  series. 

The  outline,  its  ornamentation  and  particularly  its  dentition,  are  very  similar  to  the  type  species. 
Nevertheless,  this  species  differs  in  its  weak  adductor  muscle  scars. 


Superfamily  nuculanacea  Adams  and  Adams,  1858 
Family  malletiidae  Adams  and  Adams,  1858 
Genus  myoplusia  Neumayr,  1884 

Type  species.  Leda  bilunata  Barrande,  1881,  by  subsequent  designation  of  McAlester,  1968,  p.  35. 


1881 
1881 
pars  1918 
1934 


Myoplusia  bilunata  perdentata  (Barrande,  1881) 

Plate  4,  fig.  1-8 

Leda  bilunata  Barrande,  pi.  270,  I,  figs  13-24. 

Leda  perdentata  Barrande,  pi.  270,  II,  figs  1-9. 

Leda  bohemica  Barrande,  Born,  p,  338,  pi.  24,  fig.  5. 

Ctenodonta  bilunata  perdentata  (Barrande),  Pfab,  p.  227,  pi.  2,  figs  12-13. 


explanation  of  plate  4 

Figs  1-7.  Myoplusia  bilunata  perdentata  (Barrande,  1881)  1,  many  internal  moulds  of  valves  of  Myoplusia  from 
Calzada  de  Calatrava  (Ciudad  Real),  middle  part  of  the  Guindo  Shales,  late  Lower  Llandeilo,  x 2.7.  2 and 
3,  Barrande’s  specimen  (1881,  pi.  270,  figs  1^4),  paratype  after  McAlester,  1968,  Sterboholy  (Czekoslovakia), 
Middle  Ordovician,  Narodni  Museum  Collections  (Prague),  left  and  cardinal  views  of  an  internal  bivalve 
mould  (phot.  J.  Khz),  x 7.  4,  Barrande’s  specimen  (1881,  pi.  270,  I,  fig-  21-24),  cardinal  view  of  a partial 
bivalve  mould  (phot.  J.  Khz),  x7.  5-7.  Calzada  de  Calatravia  (Ciudad  Real),  middle  part  of  the  Guindo 
Shales,  late  Lower  Llandeilo;  5,  internal  mould  of  a right  valve  (CC-I  2 131/OR),  x7;  6,  latex  replica  of 
the  dentition  of  a left  valve  (CC-I  2 129/OR),  x 10;  7,  latex  replica  of  a right  valve  (CC-I  2 176/OR),  x 7. 
8,  Barrande’s  specimen  (1881,  pi.  270,  II,  fig.  7-9),  also  figured  by  Pfab  (1934,  pi.  II,  fig.  13),  Sterboholy 
(Czekoslovakia),  Middle  Ordovician  Narodni  Museum  Collections  (Prague),  internal  mould  of  a right  valve 
(phot.  J.  Khz),  x 5. 


PLATE  4 


BABIN  and  GUTIERREZ-MARCO,  Myoplusia  bilunata  perdentata 


122 


PALAEONTOLOGY,  VOLUME  34 


71939  Ctenodonta  (C.)  bilunata  perdentata  Pfab  [sic],  Maillieux,  p.  33,  pi.  2,  figs  19-22. 

1966  Ctenodonta  sp.,  Babin,  p.  299,  pi.  1,  fig.  8. 

1972  Myoplusia  cf.  bilunata  perdentata  (Barrande),  Babin  and  Melou,  p.  85,  pi.  7,  figs  1 and  2. 

1973  Myoplusia  cf.  bilunata  perdentata  (Barrande),  Babin  and  Robardet,  p.  31,  pi.  2,  figs  1-6. 

Material.  Seventy-nine  internal  and  some  external  moulds. 

Localities  and  stratigraphical  range.  Upper  Llanvirn-Upper  Llandeilo  (Spanish  record  of  the  species);  muddy 
and  sandy  facies  from  the  Iberian  Cordillera  (GA-II)  and  the  Central-Iberian  zone  (ALAM-III,  Albadalejo, 
CC-I,  PSV-IV,  PZ-III,  RA-I,  RA-IV,  RE-VII). 

Description  and  discussion.  Shell  always  small,  length  less  than  10  mm  (average  for  the  Spanish  material 
6 9 mm).  Cardinal  margin  convex,  anterior  side  weakly  truncate;  pallial  edge  widely  convex  in  anterior  part 
(greatest  height  below  the  beak),  then  there  is  a faint  inflexion  and  the  elongate  posterior  end  is  less  high  than 
the  anterior  one.  Beak  prosogyrous,  situated  towards  the  anterior  third  of  cardinal  line,  on  internal  moulds 
acute  and  bent.  Adductor  muscle  scars  strongly  impressed.  Anterior  scar  oval,  perpendicular  to  cardinal  plate; 
posterior  one  with  anterior  linear  side  inclined  almost  to  the  hinge  line,  and  a rounded  posterior  side.  The 
accessory  scars  comprise  a scar  occurring  above  the  posterior  adductor. 

Dentition  paleotaxodont,  number  of  teeth  variable  (16-30)  according  to  size  of  the  shell.  Anterior  teeth 
slightly  convex;  teeth  beneath  umbo  thin  and  orthomorph;  some  concavo-convex  teeth  follow  them  without 
discontinuity  from  the  concave  posterior  teeth. 

Pfab  (1934)  reduced  the  contemporaneous  species  of  Barrande  ( bilunata  and  perdentata ) to  the  rank  of 
varieties  of  the  single  species  bilunata.  The  Spanish  specimens  belong,  without  doubt,  to  the  species  bilunata 
but  it  is  difficult  to  assign  them  to  either  subspecies.  They  have  the  anterior  end  slightly  truncated  as  in  bilunata 
bilunata  and  the  umbonal  scars  also  point  to  this  subspecies.  But  the  narrower  posterior  end  suggests  bilunata 
perdentata , which  also  sometimes  has  the  faintly  sinuous  pallial  margin  of  the  Spanish  specimens  (we  are 
indebted  to  Dr  J.  Kriz  for  photographs  of  the  specimen  figured  by  Barrande  1881,  pi.  270,  I,  figs  7-9  and  by 
Pfab  1934,  pi.  2,  fig.  13,  showing  this  morphology;  see  PI.  4,  fig.  8).  Finally,  the  hinge  with  the  particularly 
concave  posterior  teeth  is  similar  to  the  type  figured  by  Pfab  (pi.  I,  fig.  5a)  as  M.  bilunata  perdentata.  We 
therefore  refer  our  material  to  M.  bilunata  perdentata.  To  exclude  it  would  create  another  geographic 
subspecies  with  some  characters  of  each  Bohemian  subspecies.  Direct  comparison  with  the  Armorican  material 
shows  that  they  are  very  similar,  with  but  tiny  differences  such  as  in  the  position  of  the  posterior  adductor 
muscle  scar. 


Genus  cadomia  Tromelin,  1877 

Type  species.  By  monotypy  Cadomia  typa  Tromelin,  1877,  p.  48;  fig  in  Bigot,  1890,  pi.  23,  fig.  3. 


Cadomia  britannica  (Babin,  1966) 

Plate  5,  fig.  2 

1966  Ctenodonta  britannica  Babin,  p.  54,  pi.  1,  fig.  1 

19846  Deceptrix  ? britannica  (Babin),  Gutierrez-Marco  et  al.,  p.  302. 

Material.  Ten  external  moulds  of  right  and  left  valves. 

Localities  and  stratigraphical  range.  This  rare  species  is  known  only  from  six  localities  in  the  southern  part  of 
the  Central-Iberian  zone  (CHI-IV,  Fontanosas,  F1D-VI,  NE-VII,  PI-III  and  SEU-II);  muddy  facies  close  to  the 
Flanvirn-Flandeilo  boundary. 

Description  and  discussion.  All  the  valves  are  large  (length,  30^10  mm);  the  outline  is  oval  with  the  beak  in  the 
anterior  third  of  the  shell.  Dentition  with  a continuous  series  of  teeth;  6-8  anterior  teeth  convex,  6-7  teeth 
beneath  the  umbo  orthomorph,  25-30  posterior  teeth  convex.  Adductor  muscle  scars  clearly  marked,  oval,  but 
not  very  large;  accessory  scars  with  a pedal  anterior  one,  situated  behind  the  dorsal  extremity  of  the  anterior 
adductor,  and  a pedal  posterior  one  in  contact  with  the  dorsal  margin  of  the  posterior  adductor.  Another 
pronounced  scar  near  the  hinge  plate,  half-way  between  the  posterior  adductor  and  the  umbo.  Several  small 


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123 


scars  situated  on  the  anterior  side  of  the  umbonal  cavity;  lastly,  four  tiny  scars  (?)  seem  to  precede  the  posterior 
adductor  (Text-fig.  5).  The  Spanish  specimens  are  identical  with  those  from  the  Armorican  Massif  (Babin 
1966).  Generic  attribution  is  difficult;  we  tentatively  assign  this  species  to  Cadomia  because  it  is  an  inequilateral 
shell  with  numerous  taxodont  teeth  without  disruption  beneath  the  umbo.  This  species  is  not  very  common  and 
seems  to  be  restricted  to  the  basal  Llandeilo. 


text-fig.  5.  Cadomia  britannica  (Babin,  1966).  Upper  posterior 
region  of  a latex  replica  (CH-I-V  2 143/OR)  showing  four 
minute  muscle  scars  in  front  of  the  posterior  adductor. 


Subclass  isofilibranchia  Iredale,  1939 
Order  modiomorphoida  Newell,  1969 
Superfamily  modiomorphacea  Miller,  1877 
Family  modiomorphidae  Miller,  1877 
Genus  goniophora  Phillips,  1848 
Subgenus  cosmogoniophora  McLearn,  1918 

Type  species.  Goniophora  bellida  Billings,  1874. 


Goniophora  (Cosmogoniophora)  sp. 

Plate  5,  figs  3 and  4 

Material.  Twenty-five  internal  and  some  external  moulds  of  right  and  left  valves. 

Locality  and stratigraphical  range.  Recorded  only  from  the  basal  beds  of  the  La  Venta  Formation,  locality  CR- 
II  in  the  Iberian  Cordillera;  earliest  Lower  Llanvirn. 

Description  and  discussion.  Small  shell  (the  length  of  the  complete  specimens  varies  from  13  to  22  mm), 
moderately  convex,  with  a weak  umbo  and  the  typical  outline  of  Goniophora , i.e.  with  an  elongate  postero- 
ventral  angle  into  which  leads  a strong  carina  proceeding  from  the  beak.  Ornamentation  of  fine  concentric 
striae  in  front  of  the  carina,  but  of  radial  costae  on  the  slope  behind  the  carina.  Hinge  unknown.  No  muscle 
scar  observable.  With  its  radial  costae,  this  form  can  be  assigned  to  the  subgenus  Cosmogoniophora  but  no 
specific  name  can  be  proposed.  The  genus  is  known  from  the  Lower  Ordovician  to  the  Devonian. 

Genus  modiolopsis  Hall,  1847 
Type  species.  Pterinea  modiolaris  Conrad,  1838. 


Modiolopsis?  elegantulus  Sharpe,  1853 
Plate  5,  fig.  1 

1853  Modiolopsis  elegantulus  Sharpe,  p.  152,  pi.  9,  fig.  15. 


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PALAEONTOLOGY,  VOLUME  34 


Material.  Forty-four  internal  and  some  external  moulds  of  right  and  left  valves. 

Localities  and  stratigraphical  range.  Upper  Llanvirn  to  Upper  Llandeilo  (muddy  facies  only)  from  the  Iberian 
Cordillera  (HERR-I,  LU-II)  and  the  Central-Iberian  zone  (AM-I,  HD-X,  PR-IX,  PZ-III,  RA-I  III  and  VI  B 
RE-IX  and  IX  B). 

Description  and  discussion.  Inequilateral  valves  with  rectilinear  cardinal  hinge;  beak,  situated  between  the 
middle  and  the  anterior  third  and  slightly  projected.  Greatest  height  just  exceeding  the  cardinal  length.  This 
height,  extending  from  the  beak  to  the  postero-ventral  part,  coincides  with  the  greatest  convexity  of  the  shell. 
Anterocardinal  angle  rounded;  posterocardinal  angle  obtuse  (about  130°).  Shell  very  thin  and  internal  moulds 
showing  clearly  the  ornamentation  of  concentric  undulations.  Hinge  apparently  edentulous  with  a short 
ligament  groove  behind  the  beak  (?).  No  muscle  scar  visible. 

The  material  is  poor  and  does  not  allow  straightforward  generic  attribution.  The  morphology,  the 
ornamentation  and  the  edentulous  hinge  can  be  as  easily  compared  with  Modiolopsis  among  the 
Modiomorphidae  as  with  some  Posidoniidae.  The  species  elegantulus  was  described  by  Sharpe  (1853)  based  on 
a single  specimen  from  the  Ordovician  of  Portugal  and  is  probably  conspecihc  with  the  Spanish  material. 


Subclass  pteriomorphia  Beurlen,  1944 
Order  arcoida  Stoliczka,  1871 
Superfamily  cyrtodontacea  Ulrich,  1894 
Family  cyrtodontidae  Ulrich,  1890 
Genus  cyrtodontula  Tomlin,  1931 

Type  species.  Whitella  obliquata  Ulrich,  1890. 


Cyrtodontula  sp. 

Plate  5,  figs  6 and  7 

Material.  A bivalve  mould  (CHI-V  2 142/OR)  and  a partially  complete  specimen. 

Localities  and  stratigraphical  range.  Llanvirn-Llandeilo  boundary;  very  rare  in  the  Central-Iberian  zone  (CHI- 
V and  PI-III) 

Description  and  discussion.  The  badly  preserved  specimen  is  strongly  inflated  and  very  inequilateral  with  beaks 
near  the  anterior  margin.  On  this  internal  mould  some  preserved  fragments  of  the  shell  show  that  a clear 
ornament  is  superposed  on  the  concentric  striae  (PI.  5,  fig.  6).  The  dorsal  margin  is  partially  broken  behind  the 
beak  but  the  general  morphology  is  very  similar  to  that  of  many  cyrtodontids  ( Cyrtodontula , Vanuxemia)  or 


EXPLANATION  OF  PLATE  5 

Fig.  1.  Modiolopsis  ? elegantulus  Sharpe,  1853.  Pozuelos  de  Calatrava  (Ciudad  Real),  Valdemorillo  Shales, 
Upper  Llandeilo,  internal  mould  of  a right  valve  (PZ-III  2 151/OR),  x4. 

Fig.  2.  Cadomia  britannica  (Babin,  1966).  Chillon  (Ciudad  Real),  upper  half  of  the  Rio  Shales,  early  Upper 
Llanvirn,  internal  mould  of  a right  valve  (CH-I-IV,  2 143/OR),  x 1.8. 

Figs  3 and  4.  Goniophora  ( Cosmogoniophora ) sp.  Aragoncillo  (Guadalajara),  basal  beds  of  La  Venta 
Formation,  earliest  Lower  Llanvirn.  3,  partial  internal  mould  of  a left  valve  (CR-II  2 163/OR),  x 3.  4, 
internal  mould  of  a right  valve  (CR-II  2 162/OR),  x5. 

Fig.  5.  Babinka  prima  Barrande,  1881.  Navas  de  Estena  (Ciudad  Real),  lower  third  of  the  Navas  de  Estena 
Shales,  Lower  Llanvirn,  internal  mould  of  an  elongate  specimen  (NE-III  2 128/OR),  x 2. 

Figs  6 and  7.  Cyrtodontula  sp.  Chillon  (Ciudad  Real),  upper  half  of  the  Rio  Shales,  Llanvirn/Llandeilo 
boundary,  left  and  anterior  views  of  an  internal  bivalve  mould  (CH-I-IV  2 142/OR),  x 2. 


PLATE  5 


BABIN  and  GUTIERREZ-MARCO,  Middle  Ordovician  Bivalvia 


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PALAEONTOLOGY,  VOLUME  34 


some  modiomorphids  like  Plethocardia.  The  absence  of  data  concerning  the  hinge  area  makes  precise  generic 
attribution  difficult.  However,  the  apparent  absence  of  a marked  anterior  adductor  scar  indicates  tentative 
inclusion  within  Cyrtodontula.  De  Verneuil  and  Barrande  (1856,  p.  990,  pi.  27,  fig.  5)  erected  Cucullaea 
caravantesi  for  a gibbous  shell  from  the  Puebla  de  Don  Rodrigo  area  which  might  be  the  same,  in  spite  of  a 
longer  postumbonal  cardinal  part;  however  we  have  not  found  it  in  de  Verneuil’s  collections.  The  morphology 
of  this  bivalve  suggests  an  endobyssate  mode  of  life  as  proposed  by  Frey  (1980)  for  Vanuxemia.  The  genus 
Cyrtodontula  is  cited  from  the  Upper  Ordovician  in  North  America  (Richmondian)  and  in  the  Baltic  area 
(Isberg  1934),  from  the  Middle  Ordovician  of  Norway  (Soot-Ryen  and  Soot-Ryen  1960),  and  the  ‘first  records 
of  the  genus  from  the  Southern  Hemisphere’  were  given  by  Pojeta  and  Gilbert-Tomlinson  (1977)  from  the 
Arenigian  and  Trentonian  (=  late  Middle  Ordovician?)  of  Australia. 

Subclass  heteroconchia  Hertwig,  1895 

Order  actinodontoida  Douville,  1912 
Family  cycloconchidae  Ulrich,  1894 

The  diagnosis  of  the  family  given  by  Pojeta  and  Gilbert-Tomlinson  (1977)  is  ‘actinodontids  with  numerous 
elongate  teeth  with  lack  of  denticles’.  The  species  described  below,  Glyptarca  ? lusitanica,  has  microcrenulate 
teeth  and  its  attribution  to  this  family  may  therefore  be  debateable.  However,  the  family  Lyrodesmatidae  with 
crenulate  teeth  is  characterized,  by  the  same  authors,  by  ‘teeth  radiating  ventrally  from  immediately  below  the 
beak'  and  is  less  appropriate.  Thus,  we  consider  that  Glyptarca ? can  indeed  be  considered  as  a member  of 
Cycloconchidae;  the  diagnosis  of  the  family  should  therefore  be  extended  to  include  the  possible  presence  of 
denticles  on  the  teeth.  In  the  description  of  the  dentition,  we  use  the  terminology  pseudocardinals  and 
pseudolaterals  proposed  by  Pojeta  and  Runnegar  (1985,  p.  320). 


Genus  glyptarca  Hicks,  1873 

Type  species.  Glyptarca  primaeva  Hicks,  1873  by  subsequent  designation  of  Carter,  1971,  p.  258. 


Glyptarca?  lusitanica  (Sharpe,  1853) 

Text-fig.  6 

1853  Dolabra  ? lusitanica  Sharpe,  p.  151,  pi.  9,  fig.  3. 

71853  Cypricardia  ? beirensis  Sharpe,  p.  152,  pi.  9,  fig.  16. 

1856  Area  naranjoana  de  Verneuil  and  Barrande,  p.  989,  pi.  26,  fig.  12. 

1912  Actinodonta  acuta  Barrois,  Douville,  p.  440,  fig.  12  (non  Barrois,  1891). 

1918  Modiolopsis  ? lusitanica  (Sharpe),  Born,  p.  342. 

1966  Actinodonta  naranjoana  (de  Verneuil  and  Barrande)  Babin,  p.  233,  pi.  10,  figs  5,  7,  11.  See  for 
synonymy;  add: 

1970  Actinodonta  naranjoana  (de  Verneuil  and  Barrande)  Bradshaw,  p.  636,  text-figs  13-15. 

1978  Glyptarca 'naranjoana  (de  Verneuil  and  Barrande),  Morris,  pi.  1,  fig.  2. 

1984  Glyptarca  naranjoana  (de  Verneuil  and  Barrande),  Gutierrez-Marco  et  al. , p.  302. 

1985  Glyptarca  ? naranjoana  (de  Verneuil  and  Barrande),  Babin  & Gutierrez-Marco,  fig.  4. 

Material.  About  280  specimens.  The  species  is  particularly  common  at  VPA,  NE-VII,  la  Vibora,  CC-I,  RA-I 
and  FB-IV. 

Localities  and  stratigraphic  al  range.  Widely  distributed  in  the  Llanvirn  and  Llandeilo  shales  and  sandstones  of 
the  Hesperian  Massif  from  the  West-Asturian-leonese  area  (TR-III),  Iberian  Cordillera  (FB-I,  FB-IV,  LU-II, 
PO-I)  and  38  localities  in  the  Central-Iberian  zone  (AC-I-III)  Albadalejo,  CC-I  and  II,  CHI-IV,  CO-XII,  XIII 
A,  XIV-XVI,  FU-IX,  HO-IV,  LB-I,  la  Carcel,  la  Vibora,  NE-IV  and  VII,  PI-II-IV  and  IX,  PR-IX,  PSU-II- 
III  and  V,  PZ-III,  RA-I,  I A and  IV  B,  RE-VI  and  VII,  SEU-II,  SP-IV,  SVA-II,  VM-I,  VPA). 

Description  and  discussion.  Shell  equivalve,  inequilateral,  more  or  less  convex;  outline  slightly  variable  with 
subparallel  cardinal  and  ventral  margins  and  a more  or  less  truncate  posterior  side;  ornamentation  ot  fine 


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127 


text-fig.  6.  Glyptarca  ? lusitanica  (Sharpe,  1853).  a,  c.  Calzada  de  Calatrava  (Ciudad  Real),  middle  part  of  the 
Guindo  Shales,  late  Lower  Llandeilo;  a,  left  view  of  a latex  replica  of  an  external  bivalve  mould  showing  the 
ornamentation  (CC-I  2 175/OR),  x 3;  c,  internal  mould  of  an  atypical  left  valve  (CC-I  2 175/OR),  x 3.  b , Aha 
(Caceres),  middle  part  of  the  Navas  de  Estena  Shales,  early  Upper  Llanvirn;  internal  mould  of  a left  valve 
(PSV-III  2 176/OR),  x 3.  <7,  Corral  de  Calatrava  (Ciudad  Real),  middle  part  of  the  Alisedas  Shales,  late  Lower 
Llanvirn;  latex  replica  of  the  dentition  of  a left  valve  (CO-XV  2 132/OR),  x 3.3.  e , Calzada  de  Calatrava 
(Ciudad  Real),  Guindo  Shales,  late  Lower  Llandeilo;  latex  replica  of  a right  valve  showing  the  dentition  with 
the  two  short  anterior  pseudolateral  teeth,  the  small  pseudocardinals,  the  elongate  and  microcrenulated 
posterior  pseudolateral  (CC-I  2 209/OR  and  CC-I  2 140/OR),  x 3.3.  /,  Retuarta  de  Bullaque  (Ciudad  Real), 
Navas  de  Estena  Shales,  Upper  Llanvirn;  latex  replica  showing  the  microcrenulations  of  an  anterior 

pseudolateral  tooth  (RE-IV  2 137/OR),  x 10. 


concentric  striae  (Text-fig.  6a);  blunt  carina  extending  from  the  beak  to  the  posteroventral  angle.  Two 
adductor  muscle  scars  variably  impressed,  large  and  round.  Accessory  muscle  scars  varying.  Bradshaw  (1970, 
fig.  13)  figured  seven  scars  which  are  often  not  visible;  on  the  other  hand,  we  have  observed  minute  scars 
posteriorly  adjacent  to  the  anterior  adductor  scar,  perhaps  corresponding,  to  labial  palps  muscles. 

Dentition  very  characteristic.  Right  valve  (Text-figs  6e  and  la;  see  also  Babin  and  Gutierrez-Marco  1985, 
fig.  4),  with  two  short,  lamellar  anterior  pseudolaterals;  the  more  anterior  parallel  to  the  hinge  place  edge,  the 
second  oblique;  below  the  beak,  two  pseudocardinals  variably  flexed;  the  latter  is  overlapped  by  an  elongate 
posterior  pseudolateral  with  microcrenulations  on  two-thirds  or  three-quarters  of  its  length.  The  anterior  tooth 
of  one  specimen  has  peculiar  crenulations  on  its  ventral  face  (Text-fig.  6/).  Left  valve  (Text-figs  6 d and  lb) 


128 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  7.  Glyptarca  ? lusitanica , diagrams  of  dentition,  a,  right  valve,  b,  left  valve. 


showing  two  microcrenulate  posterior  pseudolaterals  which  are  often  strongly  marked  and  which  were 
considered  at  one  stage  as  taxodont  teeth:  ‘a  long  posterior  plate  parallel  to  the  hinge  line,  which  is  crossed 
by  numerous  small  teeth  or  crenulations ’ (Sharpe  1853);  ‘charniere  pourvue  de  petites  dents  placees  en  ligne 
droite'  (de  Verneuil  and  Barrande  1856)  [our  emphasis].  Opisthodetic  ligament  placed  in  a fine  groove. 

This  Ordovician  material  is  often  distorted  or  flattened,  the  morphology  of  the  shell  is  variable,  for  example 
in  the  accentuation  of  the  carina.  Nonetheless,  there  is  no  reason  to  distinguish  several  species. 
Cypricardia  ? beirensis  Sharpe  (1953)  that  de  Verneuil  and  Barrande  (1956)  also  distinguished,  without  a figure, 
also  probably  belongs  to  the  same  species  (some  specimens  from  Sharpe’s  locality,  Ribo  de  Baixo,  suggest  this 
is  likely).  Delgado  (1908)  made  use  of  the  three  designations  Dolabra  ? lusitanica , Cypricardia  ? beirensis , and 
Area  naranjoana  without  any  figures.  Born  (1918)  pointed  out  that  a form  from  Bohemia,  designated 
Modiolopsis  veter ana  by  Barrande  (1881,  pi.  259,  III)  has  some  similarities  to  the  present  species. 

The  species  Area  naranjoana  de  Verneuil  and  Barrande,  1856  ( = Dolabra  ? lusitanica  Sharpe,  1853)  was 
tentatively  attributed  to  the  genus  Actinodonta  by  Babin  (1966)  and  Bradshaw  (1970),  and  later  to  Glyptarca 
(Morris  1978).  In  fact,  this  species  differs  from  Actinodonta  (and  from  Cycloconcha ) which  have  more 
numerous  teeth  with  anterior  pseudolaterals,  radiating  more  regularly  from  below  the  umbo : these  genera  do 
not  have  microcrenulations  on  the  teeth.  Morris  (1978)  employed  the  generic  designation  Davidia  Hicks,  1873 
for  the  Ordovician  species  ramsayensis  (Hicks  1873)  and  carinata  (Barrois  1891).  Nevertheless,  Carter  (1971) 
pointed  out  that  the  type  species  Davidia  ornata  Hicks  is  unusable  and  placed  it  tentatively  in  synonymy  with 
Actinodonta  ramsayensis  whose  dentition  is  poorly  known.  In  the  same  way,  Actinodonta  carinata  Barrois  does 
not  provide  clear  information  with  regard  to  the  dentition  beneath  the  umbo  (Babin  1966).  So,  the  use  of 
Davidia  would  require  further  investigation.  Lastly,  Glyptarca  is  a poorly  defined  genus  (Carter  1971)  with  a 
small  edentulous  space  between  the  anterior  and  posterior  teeth  (Morris  1978;  Pojeta  1985).  The  Spanish 
species  does  not  present  a similar  space  in  the  dentition  (Text-fig.  7)  and  we  refer  it  to  Glyptarca  with  a query. 

Glyptarca  ? lusitanica  is  very  common  in  the  Iberian  Peninsula  and  the  Armorican  Massif.  Morris  (1978, 
pi.  1,  fig.  2)  has  figured  a specimen  from  Shropshire  and  Fortey  and  Morris  (1982)  indicate  the  presence  of 
Glyptarca  cf.  naranjoana  from  the  Hanadir  Shales  (Llanvirn)  in  Saudi  Arabia. 


Genus  ananterodonta  Babin  and  Gutierrez-Marco,  1985 
Ananterodonta  oretanica  Babin  and  Gutierrez-Marco,  1985 
Text-fig.  9/ 

This  species  has  recently  been  described  on  the  basis  of  a single  specimen  from  the  Lower  Llanvirn  of  San  Pablo 
de  los  Montes  (Toledo).  Its  phylogenetic  significance  is  considered  below. 

Family  babinkidae  Horny,  1960 
Genus  babinka  Barrande,  1881 

Babinka  prima  Barrande,  1881 

Plate  5,  fig.  5 

Spanish  material  of  this  species  has  recently  been  revised  by  Gutierrez-Marco  and  Babm  (1988);  it  is  only  cited 
and  illustrated  here.  Its  geographic  distribution  is  discussed  below. 


BABIN  and  GUTIERREZ-M  ARCO:  ORDOVICIAN  BIVALVES 


129 


? Family  coxiconchidae  Babin,  1977 
Genus  coxiconcha  Babin,  1966 

Coxiconcha  britannica  (Rouault,  1851) 

This  species  was  revised  by  Babin  (1977),  who  proposed  a subfamily  Coxiconchinae  within  the 
Modiomorphidae.  According  to  Pojeta  and  Runnegar  (1985),  the  family  belongs,  in  the  subclass  Isofilibranchia, 
with  Babinkidae  placed  amongst  the  Heteroconchia.  If  so,  it  also  seems  justified  to  place  Coxiconcha  here 
because  of  its  relations  with  Babinka. 

C.  britannica  is  very  common  (584  specimens  were  collected)  in  Llanvirn  shales  and  locally  also  in  the  early 
Lower  Llandeilo  beds.  After  its  disappearance  in  the  muddy  facies  in  younger  beds  of  the  Llandeilo,  the  last 
record  of  the  species  seems  to  be  from  the  Upper  Llandeilo  sandy  facies  (only  from  ALAM-IV).  The  studied 
material  comes  mainly  from  34  localities  in  the  Central-Iberian  zone  (AC-I,  ALAM-III  and  IV,  Albadalejo, 
CHI-I,  IV  and  V,  CO-X,  XII  and  XII  A,  FU-IX,  HD-I,  VI  and  VII,  HM-I,  IV  and  V,  NE-III-VII,  PI-II,  III 
and  IX,  PS-III,  RA-I,  I A and  I B,  RE-II,  SEU-II,  SP-IV,  VM-I,  VPA)  with  only  one  locality  in  the  West 
Asturian-leonese  zone  (TR-III). 

Family  redoniidae  Babin,  1966 

Diagnosis.  Is  here  emended  to  include  the  new  genus  Dulcineaia  (see  below).  Very  inequilateral 
actinodontoids  with  anterior  and  recumbent  beaks;  a high  myophoric  buttress  limits  the  anterior 
adductor  muscle  posteriorly;  hinge  plate  bearing  one  or  two  short  pseudocardinal  teeth  and  one  or 
two  elongate  posterior  pseudolaterals;  teeth  smooth  or  microcrenulated. 


Genus  redonia  Rouault,  1851 
Type  species.  Redonia  deshayesiana  Rouault,  1851,  p.  364. 

Diagnosis.  Redoniidae  with  smooth  teeth  and  chevron-flexed  pseudocardinals. 

Remarks.  Redonia  is  very  common  in  the  southern  part  of  the  Gondwanan  shelf,  and  the  Spanish  material  is 
significant  in  producing  new  information  leading  to  its  redescription.  Unfortunately,  the  original  description 
(with  a misorientation)  and  illustrations  given  by  Rouault  are  not  very  informative  and  the  original  material 
is  apparently  lost.  In  the  collections  of  the  University  of  Rennes,  there  are  some  very  poor  specimens,  possibly 
from  Rouault’s  collections  but  not  those  figured  by  him;  they  come  from  Gahard  (north  of  Rennes),  a locality 
cited  by  Rouault,  and  from  Guichen  (south  of  Rennes).  From  the  collections  of  the  Museum  National 
d’Histoire  Naturelle  (Paris),  we  have  examined  three  specimens  from  localities  in  Loire-Atlantique  (south  of 
the  Armorican  Massif)  none  of  which  is  Rouault’s  material.  In  the  University  of  Lyon,  Verneuil’s  collections 
contain  specimens  from  Riadan  (south  of  Rennes)  from  Vitre  (another  locality  cited  by  Rouault)  and  from  Brix 
(Manche).  In  all  these  collections,  the  specimens  are  labelled  R.  deshayesiana  or  R.  duvaliana  without 
discriminating  characters.  We  believe  that  the  descriptions  and  drawings  of  Rouault  refer  to  a single  species, 
based  on  material  from  Gahard.  The  present  revision  requires  the  designation  of  a neotype  for  R.  deshayesi. 
The  material  from  the  localities  near  Rennes  is  badly  preserved  and  its  age  is  not  precisely  known.  Therefore, 
we  select  a neotype  from  the  equivalent  Postolonnec  Formation  in  the  western  part  of  the  Armorican  Massif 
(see  below). 

Redonia  deshayesi  Rouault,  1851 
Plate  6,  figs  1-7;  Text-figs  8 and  9 
Synonymy.  See  Babin  1966,  p.  246.  Add: 

1881  Redonia  bohemica  Barrande,  pi.  268,  figs  1-26. 

1918  Redonia  deshayesiana  Rouault,  Born,  p.  339,  pi.  25,  fig.  1 a-f. 

1918  Redonia  deshayesiana  var.  duvaliana  Rouault,  Born,  p.  341,  pi.  25,  figs  2 a-f. 

1950  Redonia  deshayesi  Roemer  em.  Borneman  (sic!),  Termier  and  Termier,  pi.  163,  fig.  2. 

1950  Redonia  bohemica  Barrande,  Termier  and  Termier,  p.  87,  pi.  165,  figs  1-3,  6-9. 

1950  Redonia  megalodontoides  Termier  and  Termier,  p.  87,  pi.  165,  figs  4 and  5. 

1951  Redonia  deshayesiana  Rouault  em.  Born,  Gigout,  p.  296,  pi.  2,  fig.  14. 


130 


PALAEONTOLOGY,  VOLUME  34 


1970 
1978 
non  1978 
1984n 
19846 


Redonia  deshay esi  Rouault,  Bradshaw,  p.  638,  text-figs  16-21. 

Redonia  bohemica  Barrande,  Pojeta,  pi.  4,  figs  1—4. 

Redonia  deshayesiana  Rouault,  Pojeta,  pi.  4,  fig.  5 ( = Dulcineaia  manchegana  n.g.,  n.sp.). 
Redonia  deshay  esi  Rouault  forma  a,  Gutierrez-Marco  et  at. , p.  302. 

Redonia  cf.  deshayesi  Rouault,  Gutierrez-Marco  et  ah,  p.  19,  pi.  1,  figs  13  and  14. 


text-fig.  8.  Redonia  deshayesi  Rouault,  1851.  Some  aspects  of  the  dentition,  a,  latex  replica  of  the  left  valve  of 
a young  specimen  (CC-I  2 100/OR),  x 12.  b,  dorsal  view  of  the  internal  mould  of  the  anterior  adductor  muscle 
and  of  the  cardinal  tooth  of  a right  valve  (CC-I  2 087/OR),  x 5.  c,  latex  replica  of  the  right  valve  of  figure  b , 
x 5.  d , latex  replica  of  the  cardinal  region  of  a left  valve  (RA-I  2 1 12/OR),  x 5. 


EXPLANATION  OF  PLATE  6 


Figs  1-7.  Redonia  deshayesi  Rouault,  1851.  1 and  2,  Luciana  (Ciudad  Real),  middle  third  of  the  Navas  de 
Estena  Shales,  Lower  Llanvirn,  left  and  anterior  views  of  a bivalve  specimen  showing  the  ornamentation  (PI- 
III  2 125/OR),  x3.  3-7,  Navalpino  (Ciudad  Real),  upper  half  of  the  Navatrasierra  Shales,  early  Upper 
Llanvirn;  3,  anterior  view  of  an  internal  mould  showing  two  minuscule  muscle  scars  on  the  anterior  part  of 
the  left  umbonal  region  (RA-I  2 115Ms/OR),  x5;  4,  laterocardinal  view  of  an  internal  bivalve  mould 
showing  elongate  muscle  scars  on  the  umbonal  region  (RA-I  2 1 13/OR),  x 3.5;  5,  internal  mould  of  a right 
valve  showing  united  small  accessory  muscle  scars  (RA-I  2 115/OR),  x5;  6,  anterior  view  of  an  internal 
mould  of  a right  valve  showing  the  shapes  of  the  anterior  adductor  and  the  anterior  tooth  (RA-I  2 120/OR), 
x 6;  7,  anterior  view  of  an  internal  mould  of  a right  valve  showing  the  same  morphology  and  growth  lines 
on  the  adductor  pillar  (RA-I  2 117/OR),  x 6. 


PLATE  6 


BABIN  and  GUTIERREZ-MARCO,  Redonia  deshayesi 


132 


PALAEONTOLOGY,  VOLUME  34 


Neotype.  LPB  796  (Laboratoire  de  Paleontologie  de  Brest).  An  internal  mould  of  a right  valve;  Postolonnec 
Formation.  Locality  Morgat  by  Crozon  (Finistere,  France).  Llandeilo  (Text-fig.  9 d). 

Material.  825  specimens. 

Localities  and  stratigraphical  range.  The  species  is  very  abundant  and  reaches  a broad  distribution  (Lower 
Llanvirn  to  Upper  Llandeilo)  in  the  Tristani  beds  of  the  Cantabrian  zone  (Sueve),  West  Asturian-leonense  zone 


text-fig.  9.  Redonia  deshayesi  Rouault,  1851.  Some  specimens  from  other  countries,  a,  internal  mould  of  a 
right  valve  from  Wosek  (Bohemia)  (FSL  550  120),  x 5.  b,  latex  replica  of  a left  valve  from  Postolonnec 
(Finistere,  Armorican  Massif)  (FSL  550  084),  x 8.  c,  latex  replica  of  the  right  valve  of  figure  a,  x 5.  d , neotype, 
internal  mould  of  a right  valve,  Postolonnec  Formation  (Llandeilo),  Morgat  near  Crozon  (Finistere, 
Armorican  Massif)  (LPB  796),  x 4.  e,  latex  replica  of  a right  valve  from  Brix  (Armorican  Massif),  Llandeilo 
(FSL  550  120),  x 5./,  Ananterodonta  oretanica  Babin  and  Gutierrez-Marco,  1985.  Flolotype  and  only  known 
specimen,  internal  mould  of  a left  valve,  San  Pablo  de  los  Montes  (Toledo),  Lower  Llanvirn  (SP-IV  2 073/OR), 

x 2. 


BABIN  and  GUTIERREZ-M ARCO:  ORDOVICIAN  BIVALVES 


133 


(TR-III),  Iberian  Cordillera  (CA-II,  CR-II,  FB-I  and  IV,  HERR-I,  PS-I,  PO-I),  Central  Iberian  zone  (AC-I, 
ALAM-III,  CC-I  and  III,  CHI-I,  IV  and  V,  CO-XII  and  XIV,  GS-III,  HD-IV-VII,  HM-I  and  IV,  LB-I,  NE- 
III-VII,  PC-I,  PI-II-IV  and  IX,  PSV-II-V,  RA-I-VI,  RE-IX,  SEU-II,  SP-IV,  SVA-II,  VM-I,  VPA)  and  Ossa 
Morena  zone  (CS-IV). 

Description  and  discussion.  Shell  equivalve,  strongly  inflated  and  very  inequilateral  with  the  umbo  anterior  and 
bent  on  the  cardinal  line.  Ornamentation  concentric  with  some  grooves  of  growth  more  marked  than  others 
(PI.  6,  figs  1 and  2);  these  may  correspond  to  stasis  of  annual  growth;  according  to  this  hypothesis,  specimens 
such  as  PI-II  2125/OR  show  that  the  shell  could  reach  a length  of  10  mm  during  the  first  year  and  had  slow 
growth  subsequent  to  the  third  year. 

Anterior  adductor  muscle  scar  very  strongly  and  deeply  impressed  with  a myophoric  plate.  Some  accessory 
muscle  scars  present.  A pedal  retractor  adjacent  to  the  posterior  adductor  scar;  another  situated  at  the  internal 
basis  of  the  anterior  adductor  (Bradshaw  1970  showed  that  it  corresponds  to  the  fusion  of  two  initially  more 
or  less  distinct  scars).  Further  accessory  scars  sometimes  visible  in  the  umbonal  region.  Bradshaw  (1970,  text- 
figs  16-20)  noted  the  frequent  presence  of  two  scars  in  this  position.  In  the  Spanish  material,  we  can  see  that 
these  small  accessory  scars  vary  in  number  and  shape  as  is  to  be  expected  of  individual  or  populational 
variation.  Specimens  from  locality  RA-I  provide  good  examples  of  such  variability.  Some  have  four  small  scars 
which  are  sometimes  united  into  a single  elongate  scar  (PI.  6,  fig.  5)  or  which  remain  separate  with  an  elongate 
shape  directed  towards  the  umbo  (PI.  6,  fig  4).  One  specimen  shows  in  addition  two  minute  scars  on  the  anterior 
portion  of  the  umbo  region  (PI.  6,  fig.  3).  Pallial  line  entire. 

Dentition  very  characteristic  with  pseudolateral  and  pseudocardinal  teeth  (Text-fig.  8 a-d).  On  the  left  valve, 
a strong  pseudocardinal  chevron-shaped  tooth  with  an  anterior  point  is  flanked  by  two  sockets,  the  posterior 
of  which,  in  the  concavity  of  the  chevron,  is  very  deep;  the  two  pseudolateral  teeth  are  long  and  lamellar;  one 
of  them  begins  on  the  fore  part  of  the  hinge  plate,  the  other  is  thinner,  and  starts  behind  the  beak;  neither  is 
microcrenulated.  On  the  right  valve,  the  plate  shows  the  replicate  elements  with  a pseudocardinal  chevron- 
shaped tooth  situated  very  anteriorly,  less  developed,  and  preceding  a deep  V-shaped  socket;  the  ventral 
pseudolateral  tooth  is  situated  on  the  edge  of  the  plate;  the  dorsal  pseudolateral  tooth  is  shorter. 

This  description  is  of  material  from  the  Iberian  Peninsula  and  the  Armorican  Massif.  It  agrees  too  with 
material  from  Bohemia  designated  Redonia  bohemica  by  Barrande  (1881).  Replicas  of  this  species,  from  the 
National  Museum  of  Prague  sent  to  us  by  Dr  J.  Khz,  show  only  the  posterior  part  of  the  lateral  teeth.  However, 
in  latex  moulds  of  specimens  from  his  own  collection  (Sarka  Formation,  Llanvirnian),  as  he  wrote  (pers. 
comm.,  1985),  ‘none  of  them  shows  crenulations  of  the  lateral  teeth’.  We  can  see,  also,  that  the  plate  under 
the  umbo,  illustrated  by  Pojeta  (1978,  pi.  4,  fig.  2)  is  identical  to  that  of  R.  deshayesi.  Other  specimens  from 
Wosek  (Bohemia)  given  by  Barrande  to  de  Verneuil  and  now  housed  in  Lyon  (Text-fig.  9 a-c),  are  sometimes 
designated  R.  deshayesi  and  at  other  times  R.  bohemica.  When  they  cited  the  occurrence  of  R.  deshayesi  in 
Spain,  de  Verneuil  and  Barrande  (1856,  p.  687)  added  ‘cette  espece  se  trouve  aussi  dans  les  schistes  du  meme 
age  a Vitre,  a Gahard,  a Monteneuf  en  Bretagne  et  en  Boheme’.  This  material  exhibits  some  variation;  the 
Bohemian  specimens  are  smaller  than  the  Breton  and  Spanish  ones,  and  the  internal  mould  of  the  anterior 
adductor  is  less  pointed,  although  we  have  intermediates  from  elsewhere.  The  dentition,  however,  is  identical 
with  the  dorsally  very  concave  small  pyramid  of  the  chevron-shaped  socket,  visible  on  the  internal  mould  of 
the  right  valve  (Text-figs  8 b and  9a).  Thus,  we  consider  all  these  geographical  varieties  as  conspecific. 

R.  michelae  Babin,  1982,  from  the  Arenigian  of  the  Montagne  Noire  (South  of  France)  is  a distinct  species. 
It  is  smaller  and  has  a different  shape  of  the  anterior  adductor;  in  internal  moulds  there  is  a lamellar  pillar  with 
a ridged  top,  perpendicular  to  the  cardinal  line;  similarly,  on  the  mould,  there  is  a narrow  and  elongate 
adductor  pit  and  a large  septum,  very  different  from  R.  deshayesi.  Nevertheless  juveniles  of  R.  deshayesi  (CC- 
I 2 212/OR,  CC-I  2 213/OR)  show  a similar  morphology  (Text-fig.  10)  suggesting  an  evolutionary 
hypermorphosis  for  the  genus  Redonia. 

text-fig.  10.  Redonia  deshayesi  Rouault,  1851.  Umbonal 
region  of  the  latex  replica  of  a juvenile  specimen  (CC-I  2 
212/OR);  the  aspect  of  the  muscle  scar  and  of  the  myophoric 
plate  is  very  similar  to  R.  michelae  from  Arenig  (see  Babin 
et  al.  1982,  pi.  10,  fig.  4). 


1 mm 


134 


PALAEONTOLOGY,  VOLUME  34 
Genus  dulcineaia  n.  gen. 


Derivation  of  name.  Dulcinea,  a figure  from  Don  Quijote  de  la  Mancha. 

Type  species.  Dulcineaia  manchegana  n.  sp.  here  designated. 

Diagnosis.  Redoniidae  with  lamellar  and  microcrenulated  pseudocardinals;  elongate  pseudolaterals  variably 
microcrenulated. 


Dulcineaia  manchegana  n.  sp. 

Plate  7,  figs  1-8 

71912  Redonia  Rouault,  Douville,  p.  441,  figs  14  and  15. 

1978  Redonia  deshayesiana  Rouault,  Pojeta,  pi.  4,  fig.  5. 

19846  Redonia  deshayesi  Rouault,  forma  (l,  Gutierrez- Marco  et  al.,  p.  302. 

Holotype.  Internal  mould  of  a right  valve  showing  the  dentition,  CC-I  2 140/OR. 

Type  locality  and  horizon.  SE  of  Calzada  de  Calatrava  (Ciudad  Real),  70  m S of  the  km  47,500  of  C-410 
highway,  just  at  the  dam  base  of  the  Fresneda  reservoir,  right  bank.  Middle  part  of  the  Guindo  Shales,  late 
Lower  Llandeilo  (top  of  the  Tournemini  Biozone). 

Derivation  of  name.  After  La  Mancha  region,  Don  Quixote’s  country,  near  to  which  important  Ordovician 
fossil  localities  are  located. 

Paratypes.  CC-I  2 074/OR-2  077/OR,  2 084/OR,  2 088/OR,  2 090/OR,  2 094/OR,  2 097/OR,  2 1 10/OR,  2 
126/OR,  2 139/OR;  PZ-III  2 102/OR-2  107/OR,  2 193-2195/OR;  RA-I  2 109/OR,  2 111/OR,  2 119/OR,  2 
126/OR;  RE-VII  2 108/OR. 

Diagnosis.  As  for  genus. 

Description  and  discussion.  Shell  equivalve,  with  an  oval  outline  and  strongly  inequilateral  with  the  umbo  at 
the  anterior.  This  morphology  is  similar  to  R.  deshayesi  and  the  two  species  are  not  distinguishable  by  their 
shapes.  Posterior  adductor  muscle  scar  oval,  large,  placed  under  the  end  of  the  hinge  plate,  and  weakly 
impressed.  A small  pedal  retractor  lies  above  it.  Two  other  accessory  scars  are  sometimes  observed  in  the 
umbonal  region  of  the  shell;  one  is  situated  in  front  of  the  adductor,  at  one  third  of  the  distance  to  the  beak, 
the  other,  smaller  one  is  at  half  of  that  distance  (PI.  7,  fig.  4).  The  anterior  adductor  scar  is  deeply  impressed 
and  corresponds,  on  the  internal  moulds,  to  a strong  pillar,  as  in  R.  deshayesi.  However,  the  shape  of  the  pillar 
is  a little  different;  the  point,  generally  more  obtuse,  is  rather  more  oriented  towards  the  anterodorsal  angle 
of  the  valve  and  its  upper  face  is  less  strongly  concave  than  in  R.  deshayesi.  This  morphology,  combined  with 
the  differences  of  the  pseudocardinal  tooth,  distinguish  the  two  species  in  the  internal  moulds  (the  most 
common  material)  when  observed  by  their  anterior  side  and  even  if  the  microcrenulations  of  the  teeth  cannot 


explanation  of  plate  7 

Figs  1-8.  Dulcineaia  manchegana  n.  gen.,  n.sp.  1,  3-8,  Calzada  de  Calatrava  (Ciudad  Real),  middle  part  of  the 
Guindo  Shales,  late  Lower  Llandeilo.  1,  holotype,  internal  mould  of  a right  valve  (CC-I  2 140/OR),  x4; 

3,  paratype,  internal  mould  of  a right  valve  accompanied  by  a right  valve  of  Myoplusia  (CC-I  076/OR),  x 3; 

4,  dorsal  view  of  internal  mould  of  a right  valve  showing  the  microcrenulations  on  a tooth  and  accessory 
muscle  scars  (CC-I  2 1 10/OR),  x 8;  5,  latex  replica  of  the  same  specimen,  x 9;  6,  paratype,  latex  replica  of 
a right  valve  showing  the  dentition;  7,  internal  mould  of  a left  valve  (CC-I  2 097/OR),  x 2.8;  latex  replica  of 
the  same  specimen,  x 4.  2,  Pozuelos  de  Calatrava  (Ciudad  Real),  Valdemosillo  Shales,  Upper  Llandeilo. 
Detail  of  the  microcrenulated  anterior  tooth  on  the  left  valve  of  a relatively  young  specimen;  latex  replica 
(PZ-III  2 105/OR),  x 8. 


PLATE  7 


BABIN  and  GUTIERREZ-MARCO,  Dulcineaia  manchegana  n.gen.,  n.sp. 


136 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  11.  Dulcineaia  manchegana  n.g.  n.sp.  An- 
terior dorsal  region  of  the  internal  mould  of  a right 
valve  (CC-1  2 076/OR)  showing  the  microcrenul- 
ations  on  the  tooth  and  three  minute  scars  between 
the  adductor  pit  and  this  tooth. 


be  seen.  Some  specimens  show  a series  of  minute  scars  (2-5)  on  the  basal  part  of  the  anterior  adductor  (Text- 
fig.  11). 

The  dentition  of  D.  manchegana  is  distinctive.  The  left  valve  shows  a short  lamellar  tooth,  situated  under  the 
umbo  in  a ventral  position  and  directly  bordering  the  deep  adductor  scar.  The  faces  of  this  tooth  are 
microcrenulated  during  early  ontogeny  (PI.  7,  fig.  2);  it  ends  posteriorly  near  the  myophoric  buttress.  A long, 
pseudolateral  tooth,  begins  at  the  fore  part  of  the  shell,  at  about  the  same  place  as  the  ventral  tooth;  it  is 
generally  microcrenulated  in  its  anterior  region  and,  sometimes  for  up  to  3/4  of  its  length  (for  example  the 
paratype  CC-I  2 097/OR). 

The  systematic  position  of  Dulcineaia  is  not  clear.  We  place  it  tentatively  in  the  Redoniidae  but  the 
microcrenulations  of  the  teeth  pose  a problem.  Another  genus  with  crenulated  teeth,  Noradonta  Pojeta  and 
Gilbert-Tomlinson,  1977,  has  been  included  in  the  Lyrodesmatidae,  and  Babin  (1982)  has  referred  to  it  a 
species  from  the  Arenig,  N.  redoniaeformis  (Thoral),  which  has  a similar  morphology  (the  type-species,  N. 
shergoldi,  also  has  a deeply  impressed  anterior  adductor  muscle).  However,  the  species  of  Noradonta  have 
several  anterior  teeth  below  the  beak  which  more  or  less  radiate  from  it ; moreover  the  posterior  elongate  teeth 
are  strongly  crenulated.  On  the  other  hand,  Dulcineaia  has  only  one  or  two  teeth  beneath  the  umbo  which  are 
parallel  to  the  dorsal  margin  of  the  shell;  and  like  the  pseudolaterals,  they  are  slightly  microcrenulated  for  part 
of  their  length  or  even  entirely  smooth.  We  suggest  this  species  is  allied  to  Redonia  but  it  is  clear  that  the 
differences  between  these  genera  are  becoming  less  conspicuous  with  the  new  discoveries. 

Finally,  it  is  interesting  to  note  that  the  stratigraphic  distribution  of  D.  manchegana  is  more  restricted  than 
that  of  R.  deshayesi.  The  latter  is  known  from  the  Llanvirn  (Armorican  Massif,  Bohemia,  Portugal,  Spain, 
Morocco)  and  it  continues  in  the  Lower  Llandeilo  even  when  D.  manchegana  appears  (the  two  species  are 
present  simultaneously  in  locality  CC-I).  Afterwards  D.  manchegana  seems  to  remain  alone  in  Upper  Llandeilo 
levels  together  with  the  trilobites  Placoparia  borni.  In  this  way,  D.  manchegana  could  be  an  index  fossil  but  its 
geographic  extension  may  have  been  restricted.  In  the  literature,  Douville  (1912,  p.  441)  has  figured  two 
valves  of  Redonia , the  dentition  of  which  suggests  that  they  belong  to  D.  manchegana.  This  material  came  from 
the  Ordovician  of  Brix  (Normandy)  and  is  in  the  collections  of  the  Ecole  des  Mines  (Paris),  at  present  in  Lyon. 
We  have  found  in  these  collections  two  right  valves  from  the  same  locality  (and  probably  from  the  Moitiers 
d’Allonne  Formation)  and  they  are  exactly  determined  R.  deshayesi  by  the  shape  of  the  teeth  without 
microcrenulations  (Text-fig.  9e).  So,  the  observation  of  Douville  remains  enigmatic.  On  the  other  hand,  we 
have  found  in  de  Verneuil’s  collections,  in  Lyon,  some  poor  but  interesting  specimens  from  Vitre  (Brittany);  the 
morphology  of  the  anterior  adductor  and  the  visible  part  of  the  dentition  show  that  they  do  not  belong  to  R. 
deshayesi',  they  may  in  fact  be  D.  manchegana. 


SOME  THOUGHTS  ON  EARLY  ORDOVICIAN  BIVALVE  PHYLOGENY 

‘The  strength  of  any  phylogenetic  hypothesis  must  be  found  in  its  corroboration  by  disparate  data 
sets’  (Laws  and  Fastovsky  1987).  Among  these  data  sets,  morphology  and  stratigraphic 


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137 


superposition  are  both  incomplete  but  their  ‘value  and  significance  in  phylogeny  reconstruction  are 
unquestionable’.  With  these  remarks  in  mind,  what  can  we  attempt  with  respect  to  Ordovician 
bivalve  phylogeny?  The  present  material  from  the  Middle  Ordovician  is  interesting  because  in  the 
Llanvirn  a marked  explosion  of  diversity  of  bivalve  faunas  occurs. 

After  the  first  known  minute  bivalves  (Fordillidae)  from  the  Lower  Cambrian,  the  pelecypods 
remain  very  poorly  known  from  the  Middle  and  Upper  Cambrian  and  during  the  Tremadoc,  with 
only  five  or  six  species  worldwide  (Pojeta  1985:  Pojeta  and  Runnegar  1985)  and  the  age  of  some  of 
these,  like  Afghanosdesma  (Desparmet  et  al.  1971 ),  is  uncertain.  The  faunas  from  the  Arenig  are  also 
geographically  restricted  despite  some  radiation.  During  the  Llanvirn,  the  diversity  of  the  faunas 
increases,  but  they  are  dominated  by  palaeotaxodontids  and  actinodontids.  The  phyletic  relations 
of  these  two  groups  remain  obscure.  In  the  opinion  of  Douville  (1912),  Babin  (1966),  Morris  and 
Fortey  (1976),  and  Morris  (1978),  the  actinodont  type  was  probably  the  more  primitive.  Pojeta 
(1978)  expresses  doubt  about  this  after  the  description  by  Allen  and  Sanders  (1973)  of  the  curious 
living  deep-sea  protobranch  Praelametila  and  he  concludes  ‘which  group  gave  rise  to  the  other  is 
not  clear’.  Since  the  recent  study  on  Pojetaia  and  its  earlier  appearance  (Pojeta  1985),  Pojeta  and 
Runnegar  (1985)  admit  that  the  heteroconchs  might  be  descended  from  the  paleotaxodontids ; the 
latter  are  considered  as  occurring  earlier,  but  this  needs  confirmation,  in  particular  from  the  fauna 
described  by  Harrington  (1938)  from  Argentina.  It  seems  that  ‘during  the  Lower  Ordovician, 
nuculoids  are  not  so  well  represented  as  the  Cycloconchacea’  (Morris  1978).  In  contrast,  during  the 
Middle  Ordovician,  paleotaxodontids  appear  more  diversified.  Praenuculidae  with  an  elongate 
anterior  end  become  abundant.  Cardiolaria , with  resorption  during  ontogeny  of  the  umbonal  teeth, 
might  ‘indicate  a very  early  stage  in  the  migration  of  the  external  ligament  onto  the  hinge  plate’ 
(Bradshaw  1970).  Ekaterodonta  hesperica  is  a Llanvirn  species  of  this  genus  originally  described 
from  the  Arenig  of  the  Montagne  Noire  (Babin  1982)  and  which  is  related  to  another  Llanvirnian 
genus  from  Spitzbergen,  Tironucula  Morris  and  Fortey,  1976.  The  potential  phyletic  interest  of  these 
forms  is  to  show  the  possible  evolution  of  a pseudolateral  tooth  ‘by  extending  one  arm  of  the  V (of 
a chevron  tooth)  and  suppressing  the  other’,  as  described  by  Allen  and  Hannah  (1986)  with  regard 
to  the  Recent  and  conservative  Lametilidae  and  Siliculidae.  The  arrangement  of  the  pedal  muscles 
of  the  Ordovician  paleotaxodontids  is  also  primitive  (cf.  Myoplusia ) and  is  later  modified  in  the 
Upper  Palaeozoic  protobranchs  (Driscoll  1964). 

However,  in  the  actinodontids,  the  diverse  arrangements  of  the  teeth  justify  the  taxonomic 
discrimination  of  several  genera,  even  though  some  of  them  are  monospecific,  and  there  is  a rapid 
diversification.  The  relationships  between  them  remain  imprecise  because  of  the  durations  of  these 
stages  (about  20  My  for  Llanvirn  and  Llandeilo  together,  after  Odin  1985)  and  the  incomplete 
biostratigraphical  record.  In  addition,  we  are  not  able,  on  the  present  data,  to  decide  on  ancestral 
and  derived  characteristics  in  the  arrangement  and  structures  of  the  teeth.  Thus,  we  cannot  suggest 
precise  phyletic  relationships  other  than  to  underline  some  particularities  of  the  species  described 
above. 

The  dentition  of  Ananterodonta , known  from  a single  specimen,  resembles  that  of  the  living 
solemyoid  Nucinella  of  which  Allen  and  Sanders  (1969)  said  ‘it  should  be  considered  as  a rather 
specialized  member  of  the  Actinodonta ’.  This  remarkable  fossil,  may  give  us  an  indication  of  the 
pteroconch  Cyrtodontidae  in  the  trend  of  reduction  of  the  anterior  part  of  the  posterior 
pseudolaterals. 

Another  problem  concerns  the  relationships  between  actinodontids  with  and  without 
microcrenulations  on  the  teeth.  A review  of  the  presence  of  microcrenulations  in  diverse  Palaeozoic 
bivalve  groups,  to  compare  with  the  ontogeny  of  living  pelecypods,  has  been  made  by  Babin  and 
Le  Pennec  (1982).  Microcrenulations  are  known  from  the  Upper  Tremadoc  and  the  Arenig  in 
Babinka  and  lyrodesmatids  like  Tromelinodonta  and  Noradonta.  The  discovery  of  Dulcineaia  poses 
the  problem  of  the  relationships  of  this  genus  with  Redonia , and  others.  Formerly,  it  was  considered 
that  ‘it  is  highly  likely  that  Redonia  developed  from  a form  with  a dental  plate  similar  to  that  of 
Actinodonta.  The  fusion  of  the  teeth  in  both  forms  follows  a similar  pattern  but  has  been  more 
extreme  in  Redonia'  (Bradshaw  1970),  following  research  on  Actinodonta  naranjoana 


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PALAEONTOLOGY,  VOLUME  34 


( = Glyptarca  ? lusitanica).  It  appears  that  Redonia  was  derived  from  a primitive  actinodontid,  but  it 
is  not  a descendant  of  Glyptarca ? which  appeared  later.  Morris  and  Fortey  (1976)  granted  particular 
phyletic  importance  to  the  microcrenulations,  suggesting  ‘that  the  origin  of  the  posterior  hinge  teeth 
in  the  Nuculoida  ...  is  by  the  breakup  of  originally  radiating  “actinodont”  teeth  by  enlargement  of 
their  transverse  ridges’.  Nevertheless,  microcrenulations  appeared  independently  several  times; 
early  (Upper  Tremadoc-Lower  Arenig)  in  Babinka  and  lyrodesmatids,  and  later  (Upper  Llanvirn- 
Llandeilo)  in  cycloconchids  with  the  single  genus  Glyptarca  ? lusitanica.  There,  only  the  posterior 
pseudolaterals  are  microcrenulated ; this  phenomenon  appears  early  during  ontogeny  but  the 
microcrenulations  are  less  developed  than  forms  like  Noradonta.  By  contrast,  Glyptarca?  seems  to 
be  a cycloconchid  acquiring  crenulations  rather  than  a lyrodesmatid  reducing  them.  We  have  shown 
that  a specimen  from  the  Upper  Llandeilo  (Text-fig.  6 f)  has  crenulations  on  its  anterior  tooth.  As 
it  is  not  apparently  a senile  avatar,  was  it  a teratological  feature  or  a prophetic  one  without 
continuation  because  of  the  disappearance  of  the  genus? 

Still  more  curious  and  obscure  are  the  relationships  between  Redonia  and  Dulcineaia.  The  former 
is  known,  in  its  typical  morphology  ( Redonia  michelae ),  as  early  as  the  Lower  Arenig  from  the 
Montagne  Noire.  It  remained  without  notable  changes  during  the  Llanvirn  and  the  Lower 
Llandeilo  (R.  deshayesi );  suddenly,  during  the  Llandeilo,  the  genus  Dulcineaia  appears  with  a very 
similar  morphology  to  Redonia  but  with  different  cardinal  teeth.  Are  they  only  homeomorphs  or 
are  they  really  related?  We  have  preferred  the  latter  alternative  and  placed  Dulcineaia  among 
Redoniidae.  Is  it  an  atavic  reappearance  of  an  ancestral  form  and  how  did  it  occur?  Is  it  a true 
innovation,  i.e.  a case  of  divergence?  This  phenotypic  novelty  certainly  did  not  appear  as  a response 
to  new  constraints,  since  Redonia  and  Dulcineaia  lived  together,  in  a similar  habitat  and  we  do  not 
see  structural  modifications  either  of  the  whole  shell  or  of  the  hinge  plate.  Unfortunately,  we  are  not 
in  a position  to  compare  the  ontogenies  of  the  two  genera.  The  mode  of  bivalve  preservation  as 
internal  moulds  is  not  suitable  for  the  examination  of  very  minute  specimens.  Finally,  we  have  a 
young  specimen  (CC-I  2 100/bis/OR;  right  valve)  showing  a socket  followed  by  a bud,  but  we 
cannot  assign  it  to  either  of  the  genera  because  they  coexist  in  the  locality;  the  juveniles  are  possibly 
indistinguishable. 

We  should  bear  in  mind,  as  with  the  microcrenulations,  that  the  trend  towards  production  of 
crenulated  teeth  is  common  among  actinodontids  and  their  descendants.  Later,  a similar  feature 
occurs  in  the  Devonian  genus  Tanaodon  Kirk,  considered  by  Pojeta  and  Runnegar  (1985)  to  be  ‘a 
late  surviving  actinodontoid ’.  Heidecker  (1959)  has  figured  strong  microcrenulations  in 
Neoactinodonta , which  is  considered  a junior  synonym  of  Tanaodon  and  so,  in  the  Treatise, 
Tanaodon  is  defined  as  ‘with  or  without  cross  striations’  on  the  teeth.  This  however  is  probably  a 
character  without  important  taxonomic  significance  and  therefore  we  can  place  Glyptarca?  in  the 
Cycloconchidae  and  Dulcineaia  in  the  Redoniidae.  Still  more  surprising  is  the  development  of 
crenulations  on  the  teeth  among  paleotaxodontids,  like  some  Nuculites  during  the  Devonian  (Babin 
1966).  In  such  cases,  the  teeth  beneath  the  umbo  also  show  stronger  crenulations  than  the  posterior 
ones.  The  function  of  these  microcrenulations  is  not  clear,  because,  according  to  Allen  and  Hannah 
(1986),  ‘the  nuculoid  tooth  in  multiple  array  forms  an  incredibly  strong  hinge  and  in  some  species 
it  is  impossible  to  open  the  shell  wide  without  shearing  the  teeth’.  Nuculites  has  a myophoric 
buttress,  also  a character  of  Dulcineaia  and  Noradonta , but  with  a different  orientation  in  relation 
to  the  hinge  margin.  In  the  actinodontids  the  microcrenulations  restrict  movement  forwards  and 
backwards  and  in  the  palaeotaxodontids  they  restrict  dorsoventral  sliding.  There  do  not  seem  to  be 
any  general  constraints  governing  the  evolution  of  microcrenulations  in  bivalves. 


THE  PALAEOECOLOGY  AND  PALAEOGEOGRAPHICAL  SIGNIFICANCE  OF  THE 
MIDDLE  ORDOVICIAN  BIVALVE  FAUNAS 

Since  a subsequent  paper  will  include  detailed  palaeoecological  analysis  of  these  formations,  our 
treatment  here  is  brief.  There  is,  in  this  area,  a relative  stability  in  composition  of  the  benthic 
assemblages,  with  bivalves,  brachiopods,  trilobites,  echinoderms  and  ostracodes  co-occurring  for 


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139 


some  10  to  15  My;  thus  the  trophic  structure  evidently  remained  nearly  the  same  for  a long  time. 
In  these  assemblages  the  bivalves  are  mostly  shallow-burrowing,  with  deposit  feeders  the  dominant 
trophic  group  and  with  small  body  sizes.  Like  Frey  (1987a),  we  tabulate  here  the  mode  of  life  of  the 
observed  genera  (Table  1). 


table  I . 


Genera 

Mode  of  life 

Palaeotaxodonta 

Praenucula 

infaunal  deposit  feeder 

Ekaterodonta 

infaunal  deposit  feeder 

Myoplusia 

infaunal  deposit  feeder 

Cardiolaria 

infaunal  deposit  feeder 

Heteroconchia 

Babinka 

shallow  infaunal  filter  feeder 

Coxiconcha 

shallow  infaunal  filter  feeder 

Glyptarca? 

shallow  infaunal  filter  feeder 

Redonia 

shallow  infaunal  filter  feeder 

Ananterodonta 

shallow  infaunal  filter  feeder 

Pteriomorphia 

Cyrtodontula 

endobyssate  filter  feeder 

Isofilibranchia 

‘ Modiolopsis  ’ 

endobyssate  filter  feeder 

After  the  first  minute  bivalves  of  the  Cambrian,  a progressive  increase  in  size  characterizes  the 
Ordovician  diversification.  There  is  some  variation  according  to  environment.  During  the  Arenig, 
for  example,  bivalves  are  large  but  are  very  scarce  in  the  Armorican  Sandstone,  while  they  are 
numerous  and  small  in  the  muds  and  sandy  muds  of  the  Montagne  Noire.  In  the  muddy  Middle 
Ordovician  facies  of  the  southern  Perigondwanan  platform,  they  are  generally  small,  with  some 
exceptions  like  Cadomia  and  Coxiconcha  or,  occasionally,  with  individual  gigantism  (we  have  one 
specimen  some  60  mm  long).  During  the  Late  Ordovician,  it  seems  that  there  is  a further  increase 
in  size.  Most  of  the  studied  faunas  came  from  mudstones  and  siltstones.  All  these  burrowing  forms 
lived  in  soft  sediments,  mainly  muds  or  muddy  silts.  Several  were  very  shallow  borrowers.  Two 
specimens  of  Glyptarca?  (FO  2 135/OR  and  CC-I  2 208/OR)  and  one  of  Redonia  (CC-I  2 211  /OR), 
for  example,  show  a bryozoan  incrustation  (PI.  6,  fig.  1)  suggesting  that  this  part  of  the  shell 
projected  above  the  sediment-water  interface;  this  attitude  is  similar  to  that  figured  by  Frey  (1987a, 
fig.  7)  for  Cyrtodontula  sterlingensis  which  is  a homeomorph  of  Glyptarca?  Two  specimens  of 
Praenucula  sharpei  show  small  pits  on  the  ventral  part  (PI.  1,  figs  5 and  6);  identical  pits  in  a pallial 
position  occur  in  a specimen  of  the  same  species  from  the  Armorican  Massif  (FSL  550  091). 

Comparing  localities,  at  La  Vibora  (the  fossils  were  collected  by  P.  Rossi  about  1974),  the  facies 
is  a fine  shallow-water  sandstone;  the  coquina  is  composed  mostly  of  bivalves;  among  177  fossils, 
there  are  167  bivalves  (94%  of  the  fauna),  2 rostroconchs  ( Ribeiria ),  and  8 brachiopods 
(Heterorthina).  The  bivalves  are  Praenucula  costae  (43-7%),  Cardiolaria  beirensis  (27-5%), 
Glyptarca  ? lusitanica  (21-6%),  and  small  undetermined  paleotaxodontids  (7-2%).  The  age  is 
probably  Upper  Llandeilo,  and  this  may  explain  the  absence  of  Redonia , but  other  forms  known 
in  these  levels,  such  as  Dulcineaia  manchegana  and  Myoplusia  bilunata , also  seem  to  be  lacking. 
Among  our  localities,  a deeper  water  bivalve  assemblage  is  apparently  provided  by  site  CR  II,  a 
black  muddy  facies  with  an  undisturbed  assemblage  of  numerous  small  specimens  of  Redonia 
deshayesi  and  other  species  such  as  Ekaterodonta  hesperica , Goniophora  sp.,  and  cf.  Ctenodonta 
escosurae.  We  consider  this  locality  as  corresponding  to  the  offshore  shelf.  Therefore,  we  agree  with 


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Morris  (1978)  that  as  early  as  the  Lower  and  Middle  Ordovician,  some  bivalves  inhabited  this  part 
of  the  shelf  in  western  Europe,  while  in  North  America  (Frey  1987r/,  b)  the  first  intrusions  into 
offshore  shelf  environments  by  pelecypods  occurred  only  during  the  Late  Ordovician.  It  is  worth 
noting  that  among  the  fauna  of  this  locality  the  genus  Ekaterodonta  occurs,  described  from  the 
Arenig  of  the  Montagne  Noire  (Babin,  1982)  and  which  appeared  here  as  a conservative  form  in  the 
deeper  water  habitats. 

Finally,  we  can  attempt  to  consider  the  spatio-temporal  distribution  of  these  faunas,  their 
relationships  with  the  ancestral  Arenig  stocks,  and  we  can  attempt  to  evaluate  migrations  and  their 
causes.  Before  plate  tectonic  reconstructions,  Spjeldnaes  (1961)  correlated  Ordovician  faunal 
provinces  with  climatic  zones.  Several  palaeogeographic  reconstructions  have  been  produced  during 
the  last  fifteen  years.  Bouyx  ( 1988)  has  compared  these  different  reconstructions;  some  of  them,  like 
that  of  Smith  (1981)  appear  inconsistent  with  the  data  on  facies  and  faunas.  Most  of  them  agree 
roughly  with  that  of  Text-figure  12  as  regards  the  southern  hemisphere  during  the  Early  Ordovician. 

The  distribution  of  bivalve  faunas  has  rarely  been  considered,  though  since  they  are  benthic  they 
are  worth  including.  A comprehensive  worldwide  comparison,  however,  still  requires  many 
investigations.  Numerous  regions  are  poorly  documented  and  new  studies  can  bring  important  fresh 
data  (see  for  Australia,  Pojeta  and  Gilbert-Tomlinson  1977,  or  for  Bolivia,  Babin  and  Branisa 
1987). 

The  present  area  belongs  to  the  Selenopeltis  trilobite  province  of  Whittington  and  Hughes  (1972) 
and,  more  interesting  for  facies  control,  our  faunas  belong  to  the  characteristic  assemblages  of 
fossils  termed  the  Neseuretus  community  type  by  Fortey  and  Owens  (1978),  a community 
considered  to  have  been  shallow-water  and  inshore  in  clastic  facies.  A cool  environment  is  inferred 
from  the  latitudinal  position  of  the  Neseuretus  community.  In  this  reconstruction,  the  postulated 
Proto-Tethys  of  Whittington  and  Hughes  (1972)  is  abandoned;  high  palaeolatitudes  from  France 
and  Iberia  were  confirmed  recently  by  palaeomagnetic  data  (Burrett  1983).  Nevertheless,  Hallam 
(1984)  reminds  us  that  eustatic  events  ‘were  in  general  more  significant  than  temperature’  in 
controlling  faunal  provinciality.  With  the  revival  of  interest  in  global  changes  of  sea  level  (Vail  et 
al.  1977),  Fortey  (1984)  has  examined  the  biological  implications  of  these  changes  during  the 
Ordovician;  he  gave  a sea  level  curve  for  Tremadoc  to  Caradoc  with  an  important  regressive- 
transgressive  event  at  the  Arenig-Llanvirn  boundary  and  another  one  during  the  Llandeilo;  this 
postulated  global  eustatic  curve  is  shown  more  precisely  in  Fortey  and  Cocks  (1986). 

The  relationships  of  the  southern  Gondwanan  shelf  to  other  parts  of  Europe  have  also  recently 
been  discussed.  Whittington  (1963)  postulated  a marine  barrier  between  Gondwana  and  Baltica  (see 
also  Babin  et  al.  1980),  but  its  dimensions  were  probably  not  important  (Bouyx  1988);  this  was 
recently  named  Tornquist’s  sea  by  Cocks  and  Fortey  (1988).  The  detailed  palaeogeography  of  the 
Gondwana  platform  itself  during  the  Lower  and  Middle  Ordovician  is  not  clearly  established 
Several  areas  appear  distinctive,  and  Cocks  and  Fortey  (1988)  suggested  ‘a  deeper  water  tongue 
between  Armorica  and  Iberia  running  from  the  region  of  Ancenis,  Brittany  to  the  Montagne  Noire 
in  Southern  France’.  The  Ossa  Morena  Zone  in  southern  Spain  is  also  anomalous.  The  Spanish 
faunas  tell  us  that  extension  of  the  range  of  bivalves  was  caused  by  the  widespread  Llanvirnian 
transgression.  But  the  Ordovician  radiation  for  example  (Sepkoski  1979)  took  place  in  the 
pelecypods  of  the  Perigondwanan  area  during  the  Arenig  rather  than  ‘in  the  transition  from  the 
Lower  to  Middle  Paleozoic’  period  of  increase  for  marine  benthic  faunas  (Bambach  1977).  We  do 
not  know  where  the  diversification  of  the  bivalve  communities  took  place  in  the  Perigondwanan 
ring.  During  the  Arenig,  pelecypods  are  cited  at  low  latitudes  (Argentina,  Australia)  and  at  higher 
latitudes  (Montagne  Noire,  Armorican  Massif,  Wales).  The  poor  correlations  between  these  areas 
do  not  permit  determination  of  the  thermal  preferences  of  the  primitive  bivalve  populations.  On  the 
southern  Gondwanan  shelf  in  the  Montagne  Noire,  corresponding  to  the  ‘deeper  water  tongue’  on 
the  platform,  pelecypods  are  known  as  early  as  the  Late  Tremadoc  (Babinka)  and  then  diversified 
during  the  Lower  Arenig  ( Babinka , Redonia , Svnek , Thor  alia,  Noradonta,  Coxiconcha , Ekatero- 
donta)', they  inhabited  fine  sediments  and  probably  cool  waters.  This  area  could  have  been  the  place 
of  origin  of  several  genera.  During  the  Upper  Arenig,  some  pelecypods  of  larger  size  colonized 


BABIN  and  GUTIERREZ-M  ARCO:  ORDOVICIAN  BIVALVES 


141 


o Ekaterodonta 
o Myoplusia 
a Babinka 
® Coxiconcha 
* Glyptarca  ? 
a Redortia 


text-fig.  12.  Distribution  of  some  bivalve  genera  during  Arenig  (Montagne  Noire)  and  Llanvirn-Llandeilo 
(other  countries)  on  the  Perigondwanan  platform.  Palaeogeographic  reconstruction  after  Gutierrez-Marco  and 
Rabano  (1987);  land  areas  are  shaded.  See  also  Cocks  and  Fortey  (1988)  for  biofacies  distribution  around 

Gondwana. 

shallow-water  sands  like  those  of  the  Armorican  Sandstone,  with  actinodontids,  lyrodesmatids 
( Tromelinodonta ),  and  scarce  palaeotaxodontids  ( Praenucula  oehlerti).  The  rapid  expansion  of  the 
Llanvirn  is  not  uniform  and,  during  the  whole  Middle  Ordovician,  the  reasons  for  particular 
distributions  and  migrations  remain  obscure.  Among  the  palaeotaxodontids,  which  often  constitute 


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PALAEONTOLOGY,  VOLUME  34 


the  dominant  element,  the  genus  Praenucula  is  common  in  the  Ibero-Armorican  province  as  well  as 
Morocco,  Bohemia  or  on  the  marginal  edge  of  the  shelf  (e.g.  Ardenne)  but  the  species  are  not 
determined  with  certainty  and  it  is  difficult  to  follow  the  possible  migrations.  The  case  of 
Ekaterodonta  is  peculiar.  This  genus,  known  in  the  Arenig  from  the  Montagne  Noire,  appears  like 
a relict  in  some  deeper  facies  during  the  Llanvirn  from  the  Hesperian  Massif  but  it  is  present  at  the 
same  time  in  Bolivia  at  a lower  latitude,  and  the  first  described  Tironuculidae,  Tironucula , is  a 
contemporaneous  form  from  the  Laurentian  platform.  During  the  Llandeilo,  Myoplusia  bilunata 
existed  in  Brittany  and  Spain  (and  perhaps  in  the  Ardenne?);  and  persisted  into  the  Caradoc  in  the 
Armorican  Massif  and  Bohemia.  But  another  common  Ibero-Armorican  species,  Cardiolaria 
beirensis,  is  unknown  elsewhere.  Still  more  curious,  Tancrediopsis  ezquerrae , a common  form  in 
Portugal  and  Brittany,  remains  to  be  found  in  the  Spanish  area. 

If  we  compare  the  palaeotaxodontids  from  other  areas  of  the  world,  we  can  see  a sudden 
diversification  during  the  Llanvirn  in  varied  facies  from  lower  latitudes  (North  America,  Baltica, 
Australia,  South  America).  In  these  regions  there  are  representatives  of  Ctenodonta  and  Deceptrix 
but  also  there  are  often  numerous  genera  unknown  in  the  Ibero-Armorican  region,  like  Similodonta? 
in  Norway  (Soot-Ryen  and  Soot-Ryen  1960)  or  the  various  genera  described  from  Australia,  such 
as  Eritropis  and  Johnmartinia , which  are  frequently  found  in  sandstones  (Pojeta  and  Gilbert- 
Tomlinson  1977). 

The  isofilibranchs  and  pteriomorphids  are  scarce  in  the  Ibero-Armorican  area;  but  they  are  more 
frequent  and  diversified  in  Baltica  (Soot-Ryen  and  Soot-Ryen  1960)  in  the  more  calcareous  facies 
and  warmer  waters. 

The  actinodontids  and  their  problematic  allied  genera,  Babinka  and  Coxiconcha , are  also 
interesting  in  their  spatio-temporal  distributions.  Babinka  prima  appears  early  in  the  Upper 
Tremadoc  in  the  Montagne  Noire  and  it  remains  until  the  Upper  Arenig  in  this  region  where  post- 
Arenig  rocks  are  unknown.  During  the  Llanvirn,  the  same  species  occurs  in  Bohemia  and  in  the 
Hesperian  Massif,  but  it  remains  unknown  among  similar  communities  and  environments  in 
Portugal  and  in  the  Armorican  Massif.  On  the  other  hand,  B.  oeldandica  was  described  by  Soot- 
Ryen  (1969)  from  Baltica  around  the  Arenig-Llanvirn  boundary.  Thus,  from  the  Montagne  Noire, 
Babinka  migrated  to  some  sites  on  the  southern  Gondwanan  shelf  without  recognizable  specific 
variation  during  a time  interval  of  about  20  My  and  it  crossed  Tornquist’s  sea  to  reach  the  Baltica 
shelf,  giving  rise  to  another  species.  Coxiconcha  is  also  known  from  the  Montagne  Noire  as  early 
as  the  Lower  Arenig  and  remained  there  during  the  whole  stage.  During  the  Llanvirn  and  Llandeilo, 
the  genus  was  abundant,  with  a larger  species  C.  britannica , in  the  muddy  sea  floors  of  the  Ibero- 
Armorican  area  and  it  migrated  along  the  Gondwanan  coast  giving  another  species  in  Bolivia. 
However,  it  remains  unknown  from  Bohemia. 

Among  the  Cycloconchidae,  Glyptarca  ? is  a genus  with  a widespread  distribution  on  the 
southern  Gondwanan  shelf.  Originally  described  from  Portugal,  it  is  common  from  the  Middle 
Ordovician  in  the  whole  Ibero-Armorican  province,  usually  in  muds,  but  sometimes  adapted  to 
sandy  sediments.  Glyptarca  is  cited  from  Saudi  Arabia  (Fortey  and  Morris  1982)  and  may  occur  in 
Morocco  (Babin  unpublished)  but  is  unknown  from  Bohemia  (Born  1918).  Finally,  the  Redoniidae 
present  other  differences.  The  first  known  Redonia , R.  michelae , is  known  from  the  Montagne  Noire, 
as  early  as  the  Lower  Arenig.  Like  the  other  bivalves  from  these  environments,  relatively  deep  on 
the  platform,  this  species  is  a small  one.  In  the  Armorican  Sandstone,  from  the  Upper  Arenig,  the 
poorly  known  R.  boblayei  (Barrois  1891)  is  larger.  During  the  Llanvirn,  Redonia  deshayesi  is  an 
important  element  of  the  benthic  Ibero-Armorican  communities.  It  is  also  present  in  Bohemia  in 
similar  environments  and  in  Morocco  in  sandy  facies.  The  genus  was  cited  as  R.  anglica  in 
Shropshire  by  Salter  (1866).  Redonia  appears  to  have  been  eurytopic  with  regard  to  grain-size  but 
was  probably  a stenotherm,  preferring  cold  water.  We  can  thus  explain  its  presence  in  the  deeper 
zones  of  the  platform  (Montagne  Noire  during  the  Arenig;  locality  CR  II  in  the  Hesperian  Massif 
and  occurrence  in  the  Ossa  Morena  Zone  during  the  Llanvirn)  as  in  the  higher  latitudes  (Morocco). 
Around  Gondwanaland  Redonia  is  unknown  from  South  America  or  Australia,  where  it  was 
erroneously  cited  by  Warris  (1967)  (after  Pojeta  and  Gilbert-Tomlinson  1977).  The  new  genus 
Dulcineaia  is  known  only  from  the  Llandeilo  of  the  Hesperian  Massif. 


BABIN  and  GUTI E R R EZ-M  ARCO:  ORDOVICIAN  BIVALVES 


143 


In  conclusion,  this  study  of  Spanish  bivalve  faunas  underlines  the  necessity  for  further  new 
investigations.  Bivalve  distribution  is  apparently  complex,  with  some  endemics.  To  confirm  this, 
more  data  are  needed  from  the  Ibero-Armorican  area,  the  Bohemia  faunas  require  revision,  and  the 
Moroccan  ones  need  to  be  studied.  As  Boucot  (1985)  has  stated  ‘the  pelecypods  are  a group 
deserving  a great  deal  more  taxonomic  attention  and  collecting  before  one  can  be  certain  of  such 
conclusions’. 


Acknowledgements . We  are  indebted  to  Dr  N.  J.  Morris  (British  Museum,  Natural  History)  for  the  loan  of 
Sharpe’s  material,  to  Dr  J.  Kriz  (Geological  Survey,  Prague)  for  casts  of  Barrande’s  collections,  to  Mme  Y. 
Gayrard  (Museum  National  d’Histoire  Naturelle  Paris)  for  the  loan  of  Redonia , and  to  Professor  W.  Hamman 
(University  of  Wurzburg,  R.F.A.)  for  giving  material  from  the  localities  ‘ Albadalejo’,  CHI-IV,  CO-XV  and 
FU-IX.  We  wish  to  thank  Dr  L.  R.  M.  Cocks  for  correcting  and  improving  a large  part  of  the  English 
manuscript,  N.  Podevigne  for  photography  and  D.  Barbe  for  typewriting.  Anonymous  reviewers  made  helpful 
criticisms  for  which  we  are  grateful. 


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Centre  des  Sciences  de  la  Terre 
et  U.R.A.  11  du  C.N.R.S. 

Universite  Claude  Bernard,  Lyon  I 
27-43,  boulevard  du  11  novembre  1918 
69622  Villeurbanne  Cedex,  France 

juan-carlos  gutierrez-marco 
U.E.I.  de  Paleontologia 

Instituto  de  Geologia  Economica  (C.S.I.C.-U.C.M.) 
Typescript  received  12  April  1989  Facultad  de  Ciencias  Geologicas 

Revised  typescript  received  4 April  1990  28040  Madrid,  Spain 


SPONGIOPHYTON  FROM  THE  LATE  LOWER 
DEVONIAN  OF  NEW  BRUNSWICK  AND  QUEBEC, 

CANADA 

by  PATRICIA  G.  GENSEL,  WILLIAM  G.  CHALONER  Gild  WILLIAM  H.  FORBES 


Abstract.  Compressed  cuticles  of  the  dorsiventral,  presumed  parenchymatous  land  plant  Spongiophyton  are 
described  from  several  late  Lower  Devonian  (Emsian)  localities  in  northern  New  Brunswick  and  Gaspe, 
Quebec.  They  are  assigned  to  Spongiophyton  minutissimum  Krausel.  Thalli  branch  dichotomously  several  times 
in  more  than  one  plane  and  also  produce  short  vertical  branches.  No  reproductive  structures  are  present.  The 
cuticle  is  thicker  dorsally,  often  being  up  to  250  /tm  thick  as  opposed  to  30-60  /mi  for  the  ventral  cuticle.  Small 
circular  to  elliptical  pores  occur  on  the  dorsal  surface  or  along  thallus  margins.  The  many  specimens  obtained 
provide  considerable  information  on  variation  in  vegetative  morphology  and  suggest  a growth  habit  similar 
to  some  extant  thallose  liverworts.  This  new  information  expands  the  concept  of  S.  minutissimum  and  supports 
the  genus  as  a taxon  quite  distinct  from  Nematothallus , Protota.xites,  or  other  plants  with  a putative 
filamentous  organization.  Absence  of  reproductive  structures  precludes  improved  understanding  of 
Spongiophyton' s relationship  to  algae  or  vascular  plants;  the  presence  of  a resistant  cuticle  argues  against  these 
plants  representing  algae.  They  may  instead  represent  a transitional  grade  between  algae  and  higher  plants.  The 
new  specimens  also  demonstrate  that  these  cuticles  are  susceptible  to  some  differential  breakdown  as  a result 
of  oxidation  or  heat.  Degradation  features  include  superficial  cracks  or  pockmarks,  a spongy  appearance,  or 
a pseudocellular  pattern.  It  is  suggested  that  possibly  some  features  of  other  enigmatic  Devonian  plants  (e.g. 
Orestovia,  Rhytidophyton , etc.)  may  have  resulted  from  degradation  of  their  very  thick  cuticles. 

In  addition  to  the  many  genera  of  vascular  plants  that  are  known  to  occur  in  the  Lower  Devonian 
of  New  Brunswick  and  Gaspe  (for  a summary  see  Gensel  1982),  a variety  of  non-vascular  plant 
types  also  are  present.  These  may  represent  several  genera  and  most  probably  several  different 
lineages  of  non-vascular  plants,  many  of  which  still  require  detailed  study.  This  paper  describes  one 
very  abundant  form,  obtained  from  several  outcrops  of  Early  Devonian  rocks  in  New  Brunswick 
and  Gaspe,  Quebec,  referable  to  Spongiophyton  minutissimum  Krausel. 

These  fossils  were  first  collected  by  Sir  J.  W.  Dawson  and  briefly  described  in  his  introductory 
comments  appended  to  Penhallow’s  publication  on  Protota.xites  of  1889.  In  those  comments, 
Dawson  (p.  34)  noted  ‘In  the  sandstones  of  Gaspe  basin  there  occur  laminae  of  a resinous  substance 
resembling  amber  . . . ’ which  often  were  associated  with  carbonaceous  films.  He  concluded  that  these 
entities  represented  a secretion  of  the  bark  of  some  tree,  suggesting  somewhat  indirectly  that  the 
source  may  have  been  Protota.xites. 

Our  investigations  show  that  these  fossils  are  not  resinous  secretions  but  rather  are  cuticles  of 
thalloid  organization  referable  to  Spongiophyton , first  described  from  the  Middle  Devonian  of 
Brazil  by  Krausel  (1954).  Krausel  established  the  family  Spongiophytaceae  to  include 
Spongiophyton ; this  family  subsequently  was  expanded  to  include  up  to  6 genera  (listed  in  Table  1). 
Despite  the  diverse  array  of  thalloid  organisms  included  in  the  Spongiophytaceae,  definitive 
evidence  on  their  more  exact  affinities  does  not  exist.  They  have  been  regarded  as  enigmatic 
terrestrial  thallophytes  with  no  known  modern  counterparts,  possibly  related  to  an  algal  division. 
All  possess  one  feature  not  yet  found  among  algae,  namely  a resistant  cuticle.  Whether  or  not  all 
of  the  genera  included  in  this  family  are  closely  related  to  one  another  remains  uncertain. 

Sommer  (1959)  recorded  the  genus  in  several  Lower  Devonian  localities  in  the  Brazilian  states  of 
Parana,  Boias,  Piaui,  and  Maranhao  and  in  western  Bolivia.  Krausel  and  Venkatachala  (1966) 


IPalaeontology,  Vol.  34,  Part  1,  1991,  pp.  149-168,  3 pls.| 


© The  Palaeontological  Association 


150 


PALAEONTOLOGY,  VOLUME  34 


table  I . The  six  genera  attributed  to  the  Spongiophytaceae,  with  number  of  species  in  each  and  their 
distribution. 


Genera 

No.  of  species 

Geographic  distribution 

Spongiophyton  Krausel 

4 

Brazil,  Ghana,  Canada,  Poland(?),  Bolivia(?) 

Aculeophyton  Krausel  and  Venkatachala 

2 

USSR  (Siberia),  Brazil 

Orestovia  Ergolskaya 

5 

USSR  (Siberia,  Voronezh  and  other 
regions),  China 

Orestovites  Istchenko  and  Istchenko 

1 

USSR  (Voronezh  region) 

Rhytidophyton  Istchenko  and  Istchenko 

2 

USSR  (Voronezh  region) 

Voronejiphyton  Istchenko  and  Istchenko 

1 

USSR  (Voronezh  region) 

provided  comparative  data  on  several  species  of  Spongiophyton,  and  suggested  that  S.  hirsutum 
possibly  belonged  to  their  newly  described  genus  Aculeophyton.  They  also  described  fossils  as 
Orestovia  from  the  Lower  Devonian  of  Yunnan  Province,  China.  They  placed  both  Aculeophyton 
and  Orestovia  with  Spongiophyton  in  the  family  Spongiophytaceae.  Zdebska  (1978)  described 
fragments  from  a borehole  in  Poland  as  Spongiophyton , but  Edwards  (1982)  suggested  that  these 
remains,  particularly  Zdebska’s  species  2,  may  have  more  features  in  common  with  cuticles 
attributed  to  the  nematophytes  than  Spongiophyton.  Chaloner  et  al.  (1974)  provided  a detailed 
description  of  specimens  from  the  Middle  Devonian  of  Ghana  which  expands  the  circumscription 
of  Spongiophyton  nanum  and  documents  the  occurrence  of  remains  similar  to  S.  lenticulare.  Boureau 
and  Pons  (1973)  described  remains  from  southern  Bolivia  which  they  assigned  to  Spongiophyton 
lenticulare , using  these  and  associated  plant  remains  to  date  the  sediments  as  Early  Devonian.  Their 
identification  may  need  reconsideration.  Our  report  represents  the  first  undoubted  record  of 
Spongiophyton  from  the  Early  Devonian. 

Several  similar  types  of  plant,  some  of  them  included  in  the  family  Spongiophytaceae,  were 
described  by  Istchenko  and  Istchenko  (1981),  thus  demonstrating  the  existence  of  spongiophytes 
sensu  lato  in  the  Middle  Devonian  in  parts  of  Russia.  Some  of  these  exhibit  similar  morphology  to 
Spongiophyton , while  others  differ  in  cell  construction.  Again,  their  exact  relationships  are  not  clear. 

The  rather  widely-ranging  geographical  distribution  of  the  Spongiophytaceae  sensu  lato , 
including  the  fossils  discussed  here,  is  summarized  in  Table  1.  The  genus  Spongiophyton  occurs, 
without  doubt,  in  South  America  and  Africa  at  a high  palaeolatitude  (60°  S or  greater)  in  the 
Devonian.  This  report  documents  its  presence  in  Laurussia-associated  microcontinental  plates  at 
approximately  20-30°  S.  This  might  suggest  that  the  plant  exhibited  a broad  temperature  tolerance, 
since  the  southern  Gondwanan  continents  contain  faunas  indicating  cool  temperatures  at  that  time 
(see  Boucot  1985;  Livermore  et  al.  1985;  Scotese  et  al.  1985).  Other  genera  attributed  to  the  family 
Spongiophytaceae  occur  between  0°  and  30°  N palaeolatitude  in  Laurussia  (?),  Kazakhstania, 
Siberia,  and  China,  where  some  form  coals. 

The  abundance  of  Spongiophyton  in  the  Canadian  localities  suggests  that  it  was  a common 
element  of  the  vegetation,  forming  large  populations  in  some  areas.  The  large  numbers  of  individual 
thalli  obtained  at  some  localities  provide  new  information  on  the  overall  organization  of  the 
cuticularized  thallus  and  on  aspects  of  variation  in  this  genus. 


text-fig.  1.  The  occurrence  of  Spongiophyton  minutissimum  (heavy-type  S)  at  various  localities  in  New 
Brunswick  and  Quebec,  showing  their  range  in  terms  of  the  spore  assemblage  zones.  Specific  localities  are 

discussed  in  the  text. 


GENSEL  ETAL.:  CANADIAN  EMSIAN  SPONGIOPH YTON 


151 


Series 


Stage 


Provisional 
Spore  Assem- 
blage Zones 
and  Subzones 
(McGregor, 
1973,1977) 


Outcrops 

along 

Restigouche 
River,  New 
Brunswick1 


Outcrops 
along  north 
and  south 
shore  of 
Gaspe  Bay, 
Quebec2 


Middle 

Devonian 


Eifelsan 


Late 

Emsian 


Lower 

Devonian 


Early 

Emsian 


Siegenian 


V) 

V) 

c 

<D 

jD 

T3 

C 


< /) 
3 
•*-> 
flj 

3 

C 

C 

CD 


£ 'w 

a? 

CD  t 
- O 0) 


CD 

w, 

O 

a 

■o 

E 

CD 

o 


c 

CD 

X 

o 

CO 


B 


H,  I 
H - S 

A,E 


K - S 
L 


P - S 
Q -S 

M - S 
N - S 


X 


v,w 


S.T-S 


U -s 
Y -S 


( 1 Outcrops  designated  A- N.) 
i2  Outcrops  designated  S-Y.) 

text-fig.  1.  For  legend  see  opposite. 


152 


PALAEONTOLOGY,  VOLUME  34 


LOCALITY  AND  GEOLOGY 

The  major  localities  yielding  Spongiophyton  are  listed  below  and  in  Text-figure  1 ; these  include  some  of 
Dawson’s  localities  as  well  as  other  outcrops  in  New  Brunswick  and  Gaspe,  all  of  late  Lower  Devonian 
(Emsian)  age. 

1 . Atholville,  New  Brunswick:  Route  17  roadcut  into  Atholville  (Locality  P,  Text-fig.  1)  and  outcrop  along 
Beauvista  Drive  (Locality  Q,  Text-fig.  1).  Specimens  occur  scattered  on  bedding  surfaces  of  channel  fills  at  the 
former  and  as  stacks  of  individuals  in  grey  bands  of  poorly-bedded  sandy  claystone  at  the  latter. 

2.  Localities  El,  K,  M,  and  N (Gensel  and  Andrews  1984;  Text-fig.  1)  along  the  Restigouche  River,  near 
Dalhousie  Junction,  New  Brunswick,  from  which  several  vascular  plants  have  been  described  (Gensel  1982). 
The  thalli  are  sporadic  and  usually  are  intermixed  with  the  more  abundant  vascular  plant  remains. 

3.  Cross  Point,  Quebec:  at  the  Bordeaux  Quarry  and  just  to  the  north  along  Route  132.  These  rocks  were 
included  in  the  Gaspe  Sandstone  Group  (McGerrigle  1950;  Alcock  1935)  and  may  fall  within  the  LaGarde 
Formation  of  Dineley  and  Williams  (1968).  The  Bordeaux  Quarry,  one  of  Dawson’s  collecting  sites,  consists 
of  a sequence  of  red-brown  sandstones  alternating  with  conglomerate  bands.  The  thalli  occur  in  the  sandstone 
along  with  slender  ribbed  axis  (? Psilophyton)  and  Prototaxites  ‘logs’.  These  same  sediments  are  exposed  along 
a new  roadcut  on  Route  132,  where  bedding  surfaces  show  alternating  conglomerate  and  sandstone  layers,  with 
the  latter  being  a thin  ‘wash’  of  pebbles.  Thalli  densely  cover  the  bedding  surfaces  of  the  sandy  layers;  a 
specimen  of  Prototaxites  about  5 m long  and  0-8  m wide  and  numerous  smaller  ones  also  were  found  in  or 
immediately  adjacent  to  these  layers. 

4.  At  several  horizons  of  the  Battery  Point  Formation  near  Cap-aux-Os,  Gaspe  and  along  the  Laurencelle 
road  which  leads  from  Cap-aux-Os  to  Cap-des-Rosiers  Est,  Gaspe  Peninsula,  Quebec  (localities  S,  T,  U,  Y of 
Gensel  and  Andrews  1984;  Text-fig.  1).  Thalli  are  rare  to  fairly  abundant  and  appear  to  have  been  transported. 

5.  South  shore  of  Gaspe  Bay  at  several  localities.  (See  McGregor  1977  for  stratigraphic  correlations.) 

TAPHONOMY,  MATERIAL  AND  METHODS 

Considerable  variation  in  mode  of  burial  exists  among  thalli  obtained  from  these  outcrops.  The  majority  are 
spread  along  bedding  planes  of  fluvial,  often  channel-deposited  sediments,  with  no  preferred  orientation  (PI. 
1,  figs  1 and  5),  suggesting  they  were  transported  moderate  distances  prior  to  deposition.  At  locality  Q,  thalli 
occur  in  stacks  several  entities  deep  and  are  so  tightly  held  together  that  it  is  difficult  to  determine  if  they 
represent  one  plant  or  several  (PI.  1,  figs  2-4).  Thick  coverage  of  some  bedding  surfaces  by  many  such  stacks 
suggest  that  these  thalli  were  growing  in  considerable  abundance  in  some  areas  and  buried  rapidly  near  (or  at?) 
their  site  of  growth.  We  tend  to  discount  the  possibility  that  the  stacks  of  thalli  resulted  entirely  from  the  way 
in  which  they  grew  because  they  are  not  all  orientated  the  same  way  up  within  a stack. 

The  thalloid  plants  are  preserved  as  compressed  cuticles  which  occasionally  show  impressions  of  internal 
cells,  thus  mostly  demonstrating  general  morphology.  We  use  the  term  cuticle  to  refer  to  the  inert  outer 
covering  of  these  fossils.  It  is  resistant  to  oxidative  maceration  and  shows  a pattern  of  cell  outlines  on  the  inner 
surface,  features  found  in  the  cuticle  of  higher  plants.  Its  chemical  composition  is  unknown,  but  its  morphology 
compares  closely  with  the  lipid-derived  cuticle  known  to  occur  only  in  embryophytes  (higher  plants).  Although 
some  algae  apparently  possess  a thin,  protein-rich  outer  covering  that  withstands  some  acid  hydrolysis. (Hanic 
and  Cragie  1969),  these  have  not  been  shown  to  be  resistant  to  coalification  during  fossilization. 


EXPLANATION  OF  PLATE  1 

Figs  1-7.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  1-5,  various  ways  the  thalli 
occur  in  the  sediment;  1,  specimen  from  Route  132,  Quebec  locality  with  numerous  scattered  thalli  on  the 
bedding  plane;  this  specimen  was  etched  in  HF,  GSC  93004,  x0-8.  2,  surface  view  of  mass  of  thalli  from 
a poorly  bedded  siltstone,  Atholville  locality.  New  Brunswick,  GSC  93003,  x L2.  3,  lateral  view  of  mass  of 
stacked  thalli,  Atholville  locality.  New  Brunswick,  GSC  93005,  x 1-4.  4,  mass  of  stacked  thalli  from 
Atholville;  N.B.  locality,  isolated  by  maceration  in  HF,  GSC  93008,  x 3.  5,  numerous  thalli  after  etching 
a single  bedding  plane,  locality  N,  New  Brunswick,  GSC  93006,  x L2.  6,  SEM  of  thallus  isolated  by 
maceration,  distal  region  to  left;  basalmost  divisions  produce  upper  and  lower  lobes  (a),  next  1-3  divisions 
produce  side-by-side  ones  (b);  note  constrictions  in  lobes,  pores  (some  indicated  by  arrows);  roughness  and 
cracks  probably  produced  by  deterioration  under  SEM  vacuum,  x 10.  7,  thallus  fragment  with  four 
dichotomies  mostly  in  same  plane,  some  with  apices  preserved,  poral  surface  up,  lying  on  etched  surface  of 
sediment,  GSC  9301 1,  x 4. 


PLATE  1 


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PALAEONTOLOGY,  VOLUME  34 


The  cuticles  range  from  a shiny  to  dull  black  or  brown  colour  to  ones  which  are  naturally  weathered  to  a 
red-brown  colour.  Some  lighter  coloured  portions,  especially  distal  tips,  appear  waxy.  A single  specimen  may 
exhibit  some  portions  that  are  red-brown  and  others,  black;  possibly  it  was  specimens  of  this  kind  which  caught 
Dawson's  eye.  Thallus  surfaces  range  from  smooth  to  finely  pockmarked  to  rough  in  texture ; the  latter  may 
have  been  partially  corroded  during  diagenesis.  At  the  Rte.  132,  Quebec  locality,  the  sandstone  matrix 
apparently  has  imprinted  outlines  of  grains  on  the  thalli,  causing  a distinctive  deeply  pockmarked  surface 
pattern. 

Individual  thalli,  or  regions  of  a given  thallus,  vary  in  the  extent  to  which  the  cuticle  is  eroded.  Many  splits 
and  cracks  are  present,  and  more  may  be  induced  during  SEM  treatment.  Features  we  interpret  as  resulting 
from  erosion  include  differences  in  pore  outline,  the  frequent  absence  of  the  thinner,  here  designated  lower,  part 
of  the  thallus,  and  the  depressions  located  at  branch  tips. 

Bulk  maceration  of  specimens  in  HF  provided  best  results  in  elucidating  thallus  morphology.  Thalli  cleared 
only  after  long  oxidation  in  Schulze’s  solution.  Individual  fragments  reacted  slightly  differently  to  oxidation, 
suggesting  that  alteration  of  the  original  substance  prior  to  or  during  fossilization  was  quite  variable.  Selected 
specimens  were  cleared  in  Shulze's  solution  at  timed  intervals,  being  examined  and  photographed  with  a light 
microscope  at  10,  30,  and  60  minute  intervals.  At  the  end  of  48  hours,  no  evident  destruction  of  surface 
features,  or  changes  in  pore  outline  or  size,  were  observed  in  well-preserved  specimens.  In  poorly  preserved 
thalli  (partially  oxidized,  possibly  more  strongly  compressed),  pores  became  progressively  more  irregular  in 
outline  with  prolonged  maceration.  Extensively  cleared  thalli  may  appear  ‘cellular’  as  a result  of  differential 
breakdown  of  the  thick  cuticle  (PI.  3,  figs  5 and  6).  Differential  erosion,  particularly  of  the  inner  cuticle  surface, 
is  evident  in  thin  sections  (PI.  3,  fig.  1).  After  long  maceration  the  cuticles  appear  spongy  in  construction  (PI. 
3,  fig.  7).  This  probably  was  the  basis  for  Krausel’s  original  suggestion  of  a spongy  structure  (Schwammstructur) 
of  the  thallus  (see  also  Chaloner  el  al.  1974,  p.  934). 

To  determine  regularity  of  pore  spacing,  camera  lucida  drawings  were  made  of  specified  areas  of  selected 
specimens.  Using  a customized  software  program  called  MEASUR  (S.  Case,  pers.  comm.)  pore  location  was 
digitized,  spacing  calculated,  and  mean  nearest  neighbour  determined.  No  regular  pattern  was  evident. 

Rock  fragments  containing  numerous  thalli  and  individual  thalli  isolated  by  maceration  in  HF  were 
embedded  in  plastic,  sectioned,  and  ground  thin  until  transparent.  Isolated  thalli  also  were  embedded  in 
araldite  or  glycol  methacrylate,  sectioned  with  a microtome,  and  examined  with  LM  and  TEM  for 
ultrastructural  detail. 

Both  oxidized  and  unoxidized  specimens  were  mounted  on  slides  in  CMC  non-resinous  mounting  medium, 
or  were  glued  to  glass  or  cardboard  slides  with  gum  tragacanth.  Isolated  thalli  were  also  mounted  on  stubs, 
coated  with  gold-palladium  and  examined  with  an  ETEC  SEM.  Specimens  were  photographed  using  a Leitz 
Aristophot,  a Wild  Photomacroscope,  or  a Zeiss  photomicroscope.  Type  and  figured  specimens  are  stored  in 
the  collections  of  the  Geological  Survey  of  Canada  at  Ottawa,  Ontario  and  bear  the  numbers  GSC  no. 
93003-93020. 


SYSTEMATIC  PALAEONTOLOGY 

Family  spongiophytaceae  Krausel,  1954 
Genus  spongiophyton  Krausel,  1954 

Type  species.  Spongiophyton  lenticulare  (Barbosa)  Krausel,  1954,  p.  206,  figs  5-7  of  Barbosa,  1949;  from  the 
upper  Punta  Grossa  beds,  Parana,  Brazil. 


S.  minutissimum  Krausel,  1954 

Plates  1-3;  Text-figs  2-6 

Type  specimens.  P.  264/9,  Krausel  (1954),  PI.  28,  figs  72  and  73. 

Original  diagnosis.  Thallus  klein,  meist  nur  wenige  mm  messend,  gabelig  gelappt,  nrit  stark 
verdickten  Radern.  Innenbau  wie  bei  Sp.  nanum,  die  zahlreichen  Locher  aber  klein,  nadelstichartig, 
ihre  Durchmeser  meist  60  bis  100,  selten  bis  150  /mi,  oft  quer  verbreitert,  Oberflachenzellen  wabig- 
vieleckig. 


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155 


text-fig.  2.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  a,  form  3 thallus,  poral 
side  up,  with  smooth  to  finely  ridged  surface  and  few  pores  (one  at  arrow);  branching  is  mostly  in  one  plane; 
wrinkling  and  constrictions  near  lobe  apices  are  interpreted  as  a result  of  preservational  factors,  GSC  93012, 
x 7.  B,  form  2 thallus,  poral  surface  up,  with  many  pores  (arrows),  each  pore  located  in  raised  area  of  surface 
producing  bumpy  appearance.  GSC  93013,  x 12.  c,  form  3 thallus  fragment  isolated  by  maceration,  showing 
two  dichotomies  in  two  different  planes,  but  with  lobes  parallel  (arrows  indicate  pores),  GSC  93010,  x 14.  d, 
form  1 thallus  with  numerous  constrictions,  dichotomies  in  same  plane,  numerous  pores,  GSC  93015,  x 12.  e, 
form  1 thallus  bearing  numerous  short  branches  (b)  as  well  as  exhibiting  major  dichotomies,  GSC  93016,  x 9. 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  3.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  a,  an  isolated  thallus  with 
several  lobe  apices  visible,  after  short  HF  etch;  from  sequence  near  Sawdonia  acanthotheca  locality  (locality 
M),  New  Brunswick,  GSC  93007,  x 6.  B,  SEM  of  horizontal  thallus  lobes;  note  breakdown  of  apex  to  right 
and  absence  of  spores  or  other  cell  masses  in  depression,  x 46.  c,  LM  of  thallus  with  two  pairs  of  lobes, 
intermediate  between  short  vertical  branches  and  ‘normal’  lobes,  departing  from  poral  surface;  lobe  apices 
collapsed,  GSC  93017,  x 10.  d and  F,  SEM  of  thalli  with  short  vertical  branches  departing  from  poral  surface; 
apical  depressions  are  probably  a result  of  collapse  of  thinner  cuticle  in  that  area;  d,  x 15;  f,  x 11.  e,  SEM 
of  thallus  with  very  pronounced  constrictions  and  possible  short  vertical  branches  near  left,  pores,  x 12. 


Emended  diagnosis.  Thallus  cylindrical,  originally  circular  or  elliptical  in  cross  section  and  at  least 
2 cm  long.  Width  of  thalli  02-5-5  mm.  Thalli  may  exhibit  constrictions  along  their  length.  Thalli 
branch  dichotomously  several  times,  with  most  lobes  3-10  mm  long  and  with  rounded  apices.  Short 
erect  branches  (1-2  mm  long)  occur  on  poral  surface  of  some  thalli.  Pores  extend  through  cuticle 
mostly  on  one  surface,  this  being  2-4  times  thicker  than  aporal  surface  (75-250  //m  vs  30-60  //m), 
the  thicker  cuticle  extending  around  the  margins  onto  the  edge  of  the  aporal  surface.  Poral  and 
aporal  surfaces  smooth,  aporal  surface  often  longitudinally  folded.  Inner  surfaces  of  cuticle  may 


GENSEL  ETAL  . CANADIAN  EMSIAN  SPONGIOPH YTON 


157 


text-fig.  4 a-q.  Camera  lucida  drawings  of  various  Spongiophyton  minutissimum  thalli,  showing  differences  in 

extent  and  angle  of  branching,  x 6. 


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PALAEONTOLOGY,  VOLUME  34 


retain  rectangular  cell  outlines,  20-43  //m  long  and  9-12  p m wide,  although  often  degraded  and 
vermiform  in  appearance.  Pores  circular  to  oval,  randomly  spaced,  22-5  x 9 pm  to  99  x 90  pm  in 
diameter,  with  vertical,  fissured  or  (occasionally)  bevelled  edges. 

Description.  The  plant  fossils  consist  of  the  very  thick  cuticles  of  dorsiventral,  apparently  elliptical  thalli  which 
dichotomize  at  various  intervals  and  on  the  surface  of  which  pores  occur  (PI.  1,  figs  6 and  7;  Text-figs  2—4). 
Thalli  vary  mainly  in  size,  pore  density  and  location,  extent  of  branching,  and  surface  features.  Three  categories 
(forms  1-3)  of  thalli  are  recognized:  (1)  the  majority  are  smooth-surfaced,  with  a number  of  pores  located  on 
the  upper  surface,  many  branches,  and  ‘constrictions’  (PI.  1,  figs  6 and  7;  Text-fig.  2d,  e);  (2)  some  are  smooth- 
surfaced except  that  each  pore  occurs  in  a small  projection  resulting  in  an  overall  bumpy  appearance  (Text- 
fig.  2b);  and  (3)  some  thalli  are  smooth  but  longitudinally  ridged,  have  very  few  pores  located  along  lateral 
margins,  and  bear  short  vertical  branches  (Text-figs  2a,  c and  3c).  We  presently  regard  this  variability  in 
surface  topography,  pore  distribution,  and  branching  type  to  be  intra-specific,  perhaps  resulting  from  different 
parts  of  a given  plant  being  represented,  populational  differences,  and/or  preservational  differences.  We  thus 
refer  all  of  the  specimens  to  a single  species. 

The  dorsiventral  thalli  are  usually  incompletely  preserved,  being  up  to  10  mm  long  and  ranging  from 
0-3— 2-5  mm  wide  (PI.  1 ; Text-figs  2 and  3).  The  thick  amorphous  cuticle  is  smooth  externally  (Text-figs  2 and 
3)  and  rough  internally  (Text-fig.  5c,  d).  One  surface  of  the  cuticle  is  thicker  than  the  other  (PI.  3,  figs  1 and 
3);  we  interpret  the  thicker  surface,  on  which  pores  and  branches  occur,  to  be  the  dorsal  surface  of  a more  or 
less  flattened  horizontal  thallus.  Pores  may  also  occur  near  the  margins  on  both  upper  and  lower  surfaces  of 
some  (especially  form  3)  thalli. 

The  thalli  branch  dichotomously  at  least  six  times  at  0-2-3  mm  intervals,  being  dense  on  some  specimens  and 
very  sparse  on  others.  Branching  results  in  formation  of  lobes  extending  in  the  same  plane  as  the  original 
thallus  (PI.  1,  fig.  7;  Text-figs  2a,  b and  3c)  or  in  lobes  lying  one  on  top  of  the  other  but  still  with  their  long 
axes  parallel  (PI.  1,  fig.  6;  Text-fig.  2c).  These  may  curve  upwards,  downwards  or  laterally  (in  relation  to  the 
presumed  horizontal  position  of  the  main  thallus).  It  is  not  unusual  to  observe  three  to  four  levels  of  thallus 
lobes  belonging  to  one  specimen  in  the  stacks  of  fossils  preserved  at  the  Atholville  locality.  Additionally, 
branching  may  result  in  one  horizontal  and  one  short  vertical  lobe  at  right  angles  to  each  other  (Text-figs  2e 
and  3d,  f). 

Constrictions  occur  within  the  lobes  of  some  thalli  resulting  in  a sausage-string  type  of  appearance  (PI.  1, 
fig.  6;  Text-figs  2d,  e and  3e.  The  region  between  some  constrictions  almost  resembles  very  short  upright 
branches. 

The  upright  branches  are  1-2  mm  tall  and  occur  singly  or  in  2 rows  (Text-fig.  3d,  f).  While  upright  branches 
occur  on  all  forms  of  thalli,  they  are  most  abundant  on  form  3,  being  located  along  a centraJ  ridge  area.  Most 
exhibit  pores  (PI.  2,  fig.  2).  The  branches  are  narrower  towards  their  base  and  swell  or  flare  distally  (Text-fig. 
3a,  c,  d,  f).  Some  of  these  branches  terminate  in  rounded  apices,  often  with  a slight  depression  (PI.  2,  fig.  1 ; 
Text-fig.  3a).  A few  exhibit  small  protrusions  extending  from  the  apex  (PI.  2,  figs  3 and  4)  while  others  have 
at  their  tips  a deep  cup-like  depression  which  usually  is  irregular  in  outline  (PI.  2,  fig.  2).  The  interior  of  the 
cup  revealed  no  organization  such  as  spores  or  vegetative  propagules.  Their  structure  suggests  the  depressions 
formed  as  a result  of  collapse  and  breakdown  of  cuticle  at  the  branch  apex.  Horizontal  branch  tips  exhibit 
similar  depressions  (Text-fig.  3b). 

Circular  to  oval  shaped  pores  occur  on  the  presumed  upper  (and  thicker)  surface  of  the  first  two  forms  of 
thalli  and  along  the  margins  of  the  third  form  of  thallus  (PI.  1,  fig.  6;  PI.  3,  figs  5 and  6;  Text-fig.  2b-d).  They 
are  variably  spaced,  from  3-5  //m  to  350  pm  apart.  Average  distance  between  pores  on  selected  specimens  are 
30,  53,  75,  178,  222  pm.  The  pores  range  in  size  from  22-5  pm  long  by  9 pm  wide  to  99  pm  long  by  90  pm  wide. 
SEM  study  shows  the  pore  margin  often  to  consist  of  indented  fissures  or  rounded  outlines  (PI.  2,  figs  4 and 
6;  Text-fig.  5b).  Only  a few  exhibit  a bevelled  edge  (PI.  2,  fig.  5)  as  has  been  described  in  Spongiophyton  nanum 
by  Chaloner  et  al.  (1974). 


EXPLANATION  OF  PLATE  2 

Figs  1-5.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  1 and  2,  SEM  of  apical 
region  of  vertical  branches  showing  various  degrees  of  collapse;  1,  x 40;  2,  x 31.  3 and  4,  general  view  and 
detail  of  short  vertical  branches  with  protrusion  at  apex  - also  appearing  somewhat  degraded ; note 
occurrence  of  pores  on  branches  (arrows);  3,  x38;  4,  x 120.  5,  SEM  of  pore  with  bevelled  edges,  some 
evidence  of  internal  surface  of  cuticle,  x 1100.  6,  SEM  of  pore  with  irregular  margin,  x 120. 


PLATE  2 


GENSEL,  CEIALONER  and  FORBES,  Spongiophyton 


160 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  5.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  a,  interior  contents  of  a 
thallus,  GSC  93014,  x 14.  b,  LM  of  pore  on  thallus  cleared  with  Schulze’s  solution  until  nearly  translucent; 
region  around  pore  is  darker  than  rest,  GSC  93020,  x 65.  c,  SEM  of  inner  cuticle  surface,  poral  side,  showing 
outlines  of  rectangular  cells;  pore  in  centre,  x 1 10.  d,  SEM  of  inner  cuticle  surface,  poral  surface,  appearing 
vermiform,  probably  a result  of  degradation  or  borings;  pore  in  centre,  x 220.  E,  ventral  surface  of  extensively 
cleared  thallus  with  characteristic  longitudinal  folds,  GSC  93018,  x 3 1 . f,  SEM  of  inner  cuticle  surface  showing 
rectangular  cell  outlines;  this  probably  reflects  type  of  cell  construction  immediately  below  the  cuticle,  x 550. 


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161 


Thickness  of  the  poral,  presumed  upper  surface  is  75-250  pm,  and  that  of  the  aporal  one  is  about  30-60  pm. 
However,  the  form  3 thalli  exhibit  poral  and  aporal  surfaces  of  more  equal  thickness.  The  thinner  lower  thallus 
surface  often  is  partly  broken  down  or  may  be  entirely  absent  (Text-fig.  5a).  Intact  lower  surfaces  have  been 
observed  mostly  near  the  tips  of  some  lobes  and  rarely  on  more  completely  preserved  specimens.  Where 
present,  the  lower  surface  exhibits  longitudinal  ridges  and  appears  fragile  and  rather  wrinkled  except  at  the 
margins  where  it  is  transitional  to  the  thicker,  upper  surface  (Text-fig.  5e). 

Inside  the  thallus  occurs  a thin  granular  layer  of  material  which  is  usually  hght-brown  in  colour  (Text-fig. 
5a).  We  do  not  believe  this  is  rock  matrix  (left  after  HF  treatment)  but  is  a remnant  of  the  internal  contents 
of  the  thalli. 

SEM  of  a cut  transverse  section  of  the  thallus  cuticle  end-on  shows  it  to  be  amorphous  (PI.  3,  fig.  3).  Thin 
sections  examined  with  LM  and  TEM  show  an  absence  of  internal  structure  in  the  cuticle,  except  for  minute 
structures  perpendicular  to  the  outer  surface  interpreted  as  borings  or  cracks  (PI.  3,  figs  I,  2,  4).  Particularly 
interesting  is  the  absence  on  all  but  a few  specimens  of  regular  ridges  or  pegs  corresponding  to  depressions 
between  epidermal  cells  as  usually  occurs  on  vascular  plant  cuticles  or  in  other  species  of  Spongiophyton. 
However  irregularities  of  the  inner  surface  of  the  cuticle  may  represent  the  position  of  anticlinal  walls  in  life 
(PI.  3,  fig.  1).  Possibly  many  such  ridges  were  lost  or  obscured  through  erosion  of  the  inner  cuticle  surface. 

Examination  of  the  interior  cuticle  surface  has  revealed  few  with  cellular  patterns  (Text-fig.  5c,  f).  More 
frequently  they  exhibit  a vermiform  pattern  (Text-fig.  5d)  which  compares  well  with  the  ‘borings’  described 
by  Chaloner  et  al.  (1974)  for  S.  nanum  from  Ghana.  Cleared  thalli  may  exhibit  an  apparent  cell-like  pattern 
(PI.  3,  figs  5 and  6),  especially  in  photographs.  Close  examination  suggests  these  result  from  cracks  caused  by 
differential  breakdown  of  the  cuticle  after  prolonged  oxidation.  We  term  this  a pseudocellular  pattern  and 
regard  it  as  different  from  the  cell  outlines  preserved  on  some  inner  cuticle  surfaces. 

Elemental  analysis  of  two  different  specimens  show  element  ratios  similar  to  the  Ghana  Spongiophyton 
specimens  (Table  2). 


table  2.  Elemental  percentage  composition  of  Spongiophyton  from  Canada  and  Ghana.  The  difference  of  the 
sum  from  100  is  probably  accounted  for  by  oxygen. 


N 

C 

H 

S 

S.  minutissimum , Canada 

118 

74-88 

8-08 

0 

S.  minutissimum,  Canada 

103 

6901 

7-55 

0 

S.  nanum,  Ghana 

2-70 

78-40 

8-40 

— 

COMPARISONS  AND  DISCUSSION 

The  thalli  are  clearly  referable  to  the  genus  Spongiophyton  Krausel  as  emended  by  Chaloner  et  al. 
(1974).  Characters  considered  diagnostic  of  the  genus  by  the  latter  authors,  and  exhibited  by  the 
Canadian  material,  are:  a tubular  thallus  with  cuticular  covering,  dichotomous  or  sub-dichotomous 
branching  and  rounded  apices;  cuticle  with  internal  cellular  reticulum  and  circular-fusiform  pores 
largely  confined  to  one  surface  of  the  thallus.  The  Canadian  specimens  are  older  and 
morphologically  more  diverse  than  other  undoubted  Spongiophyton  specimens.  The  thalli  branch 
much  more  frequently  and  in  more  than  one  plane,  and  also  bear  more  short  vertical  branches  than 
previously  known.  Our  data  also  confirm  the  interpretation  of  Chaloner  et  al.  (1974)  that  some 
features  considered  diagnostic  by  Krausel  (dark  bodies  on  surface,  the  ‘spongy’  or  hyphal  pattern) 
are  in  fact  the  result  of  degradation,  either  during  preservation  or  the  clearing  process,  of  the  thick 
cuticles.  A pseudocellular  pattern  may  result  from  cuticular  breakdown  in  the  Canadian  specimens. 
The  constrictions  common  in  the  Canadian  thalli  probably  are  a result  of  preservational  factors  or 
may  reflect  environmental  fluctuations. 

Species  of  Spongiophyton 

The  Canadian  specimens  are  most  similar  to  Krausel’s  species  S.  minutissimum , based  on 
consideration  of  his  few  illustrations  and  brief  description  and  on  study  of  his  figured  specimens. 
Many  extensively  cleared  thallus  fragments  from  Canada  are  identical  to  5.  minutissimum  in 


162 


PALAEONTOLOGY,  VOLUME  34 


exhibiting  thickened  margins,  a character  considered  by  Krausel  as  distinctive  for  that  species. 
Thallus  appearance,  cuticle  thickness,  and  pore  shape,  size,  and  density  of  the  Canadian  material 
corresponds  very  closely  to  S.  minutissimum.  Two  possible  differences  exist  - maximum  thallus 
width  in  the  type  material  (up  to  5 mm)  exceeds  that  of  the  Canadian  fossils  and  the  dark  bodies 
described  by  Krausel  for  S.  minutissimum  are  not  found  on  the  Canadian  specimens. 

The  more  extensive  preservation  and  greater  abundance  of  specimens  from  Canada  provides 
some  characters  not  available  from  the  type  material,  limiting  further  comparison.  In  the  absence 
of  major  characters  separating  them,  and  indeed  with  strong  evidence  supporting  their  identity,  it 
seems  reasonable  to  expand  the  concept  of  a known  species  rather  than  create  a new  one. 

Differences  between  the  Canadian  specimens  and  other  species  of  Spongiophyton  include  pore 
morphology  and  size,  thallus  size,  and  cuticle  thickness.  S.  nanum  and  S.  lenticulare  are  the  best 
known  species.  The  Canadian  specimens  differ  from  S.  nanum  in  their  smaller  pores  that  mostly  lack 
a bevelled  margin.  Branching  is  more  profuse  in  the  Canadian  specimens  than  in  S.  nanum  where 
only  a few  dichotomies  or  vertical  branches  have  been  recorded.  Thallus  diameter  is  half  that  of  S. 
nanum.  Cuticle  thickness  of  the  Canadian  specimens  (up  to  250  pm)  is  much  greater  than  that  of  S. 
nanum  (60-80  /mi)  and  both  exceed  the  thickness  of  most  vascular  plant  cuticles. 

Similarly,  the  Canadian  specimens  differ  from  S.  lenticulare  in  pore  morphology,  those  of  the 
latter  species  being  elongate,  slit-like  structures  with  folded  edges  of  cuticle  extending  to  the  outside, 
and  their  thicker  cuticle.  The  internal  cellular  pattern  of  S.  lenticulare  consists  of  more  elongate  cells 
than  occur  in  either  S.  nanum  or  the  Canadian  material. 

Krausel  and  Venkatachala  (1966)  placed  S.  hirsutum  in  Aculeophyton,  because  of  its  hairlike 
papillae.  Krausel’s  species  S.  articulation  is  based  on  broken  cuticle  fragments  which  exhibit  a very 
pronounced  longitudinal  striped  pattern  and  transverse  corrugations.  These  remains  bear  some 
resemblance  to  very  over-macerated  thalli  from  Canada,  but  are  too  poorly  known  for  further 
comparison. 

Notably  absent  in  all  of  these  species  is  any  evidence  of  reproductive  structures.  Chaloner  et  al. 
(1974)  suggested  that  the  short  vertical  branches  present  on  S.  nanum  thalli  were  perhaps  sites  of 
reproductive  organs,  but  no  conclusive  evidence  was  obtained.  Many  short  vertical  branches  of  the 
Canadian  specimens  which  exhibited  depressions  were  examined  for  evidence  of  spores  or  other 
possible  reproductive  structures.  Occasionally  a mesh-work  of  material  was  present  in  the 
depressions,  but  more  commonly  only  fissures  were  observed  along  the  margins.  Both  types  of 
structure  are  interpreted  to  have  resulted  from  degradation  of  cuticle  in  apical  regions. 

Other  identifications  of  thalli  as  Spongiophyton  are  less  certain.  Boureau  and  Pons  (1973)  assigned 
thalli  from  Bolivia  to  S.  lenticulare.  Pore  shape  agrees  with  that  of  Krausel’s  S.  lenticulare  but  some 
other  features  are  problematical,  recalling  protuberances  termed  ‘capsules’  (see  below)  in  Orestovia 
and  other  genera  by  Istchenko  and  Istchenko  (1981).  The  Canadian  specimens  differ,  not  only  in 
pore  outline,  but  also  in  lacking  dark  round  bodies  and  any  evidence  of  internal  ‘hyphal 
ramifications'  as  described  for  the  Bolivian  specimens.  The  latter  should  be  compared  more  closely 


EXPLANATION  OF  PLATE  3 

Figs  1-7.  Spongiophyton  minutissimum  Krausel  from  New  Brunswick  and  Gaspe.  1,  ground  thin  section  of 
thallus  in  rock  matrix,  showing  much  thicker  poral  and  thinner  aporal  surfaces ; dark  contents  in  middle  may 
be  remains  of  inner  cells  and  may  correspond  to  the  lighter  material  seen  in  Text-fig.  5a,  x 54.  2,  TEM  of 
cuticle  showing  absence  of  internal  structure,  except  for  possible  borings,  x 700.  3,  SEM  of  transverse  cut 
surface  end-on  showing  differential  thickness  of  poral  and  aporal  surfaces  and  absence  of  structure  other 
than  borings,  x 280.  4,  LM  of  section  of  cuticle  showing  borings,  x 300.  5-7,  cleared  thalli  showing 
breakdown  of  cuticle  producing  a pseudocellular  pattern;  5,  cleared  thallus  fragment  with  thicker  margins 
as  illustrated  by  Krausel  as  typical  of  this  species;  some  evidence  of  pseudocellular  pattern  at  arrow,  shown 
enlarged  in  fig.  6,  GSC  93019,  x 31 ; 6,  detail  of  pseudocellular  pattern  of  specimen  in  fig.  5,  can  be 
emphasized  by  manipulating  lighting  of  microscope;  several  pores  visible,  apparently  ‘ringed’  by 
pseudocellular  pattern,  GSC  93019,  x 65.  7,  over-cleared  cuticle  with  spongy  appearance  similar  to  several 
illustrated  by  Krausel,  x 39. 


PLATE  3 


GENSEL,  CHALONER  and  FORBES,  Spongiophyton 


164 


PALAEONTOLOGY,  VOLUME  34 


to  the  several  thalloid  types  described  by  Istchenko  and  Istchenko  (1981)  from  the  Voronezh 
anticline,  USSR. 

As  noted  earlier,  the  specimens  described  as  Spongiophyton  by  Zdebska  (1978)  may  in  fact 
represent  other  taxa.  Although  Zdebska’s  species  1 bears  a superficial  resemblance  to  Spongiophyton 
thalli,  no  details  of  pore  type  or  cellular  construction  are  evident.  Species  2 consists  of  fragmentary 
cuticles  with  isodiametric  cell  outlines  and  pores,  suggesting  a filamentous  rather  than 
parenchymatous  organization.  Neither  type  shows  any  indication  of  being  part  of  a tubular  thallus 
like  Spongiophyton.  Edwards  (1982)  suggested  that  these  fragments  resemble  some  cuticles  of 
Nemato  thallus. 

Other  putative  spongiophytes 

Other  genera  are  allied  with  Spongiophyton  in  the  family  Spongiophytaceae  (Table  1)  because  they 
exhibit  a thalloid  construction  with  thick,  resistant,  sometimes  flexible  cuticles  and  lack  definitive 
evidence  of  reproductive  structures.  Comparison  of  these  taxa  is  hampered  somewhat  because 
interpretation  of  particular  morphological  structures  varies,  depending  on  the  worker  involved  or 
the  time  of  publication  and  corresponding  knowledge  of  Devonian  plant  diversity.  It  also  is 
extremely  difficult  to  interpret  structural  detail  on  opaque  cuticles  of  comparatively  undifferentiated 
organisms  from  photographs  and  descriptions.  The  cuticles  of  these  other  taxa  may  also  have  been 
strongly  affected  by  taphonomic  factors  and  preparation  techniques.  Thus  the  family  may  not  be 
as  coherent  as  it  appears. 

The  broad,  ribbon-like  cuticularized  axes  of  Orestovia  are  generally  similar  to  Spongiophyton  but 
longer,  wider,  less  frequently  branched,  radially  symmetrical,  and  with  a thinner  cuticle.  The  outer 
surface  is  smooth  or  covered  with  some  form  of  tiny  emergence  (depending  on  author).  Circular 
pores  with  slightly  raised  margins,  often  bordered  by  several  concentric  layers  of  mostly 
isodiametric  ‘cells’,  occur  randomly.  Extraporal  regions  bear  the  outline  of  elongate-rectangular 
cells.  The  pores  and  associated  structures  are  interpreted  by  some  workers  as  stomata  (Ergolskaya 
1934,  1936;  Krassilov  1981),  and  by  others  as  reproductive  structures  (Krausel  and  Venkatachala 
1966,  Istchenko  and  Istchenko  1981).  Krassilov  (1981)  further  reported  the  presence  of  conducting 
cells  with  thickened  wall  patterns  in  Orestovia , suggesting  it  may  be  a vascular  plant.  Our 
preparations  of  thalli,  conforming  to  Ergolskaya’s  O.  petzii  from  the  Barzas  coal,  support  some  of 
his  conclusions  concerning  stomata.  Krassilov’s  specimen  appears  papillate  (=  O.  devonica  of 
Ergolskaya),  whereas  the  specimens  available  to  us  are  smooth.  Obviously,  further  documentation 
is  needed  to  resolve  several  attributes  of  the  genus.  Despite  this,  Spongiophyton,  including  the 
Canadian  material,  can  be  distinguished  from  Orestovia  in  gross  thallus  organization,  symmetry, 
and  details  of  pore  construction. 

The  genus  Aculeophyton  was  established  by  Krausel  and  Venkatachala  (1966)  for  cuticular 
fragments  of  thalli  from  western  Siberia,  originally  placed  by  Ergolskaya  (1934,  1936)  in  Orestovia 
devonica.  The  genus  differs  from  Orestovia  mainly  in  the  presence  of  papillae,  conical  in  A.  sibirica 
and  hair-like  in  A.  hirsutum.  Krassilov  considered  that  other  characters  outweighed  the  presence  of 
papillae  and  that  Aculeophyton  and  Orestovia  are  synonymous. 

Istchenko  and  Istchenko  (1981)  described  several  new  genera  and  species  of  thalloid  plants  from 
the  Lower  Devonian  of  the  Voronezh  region,  USSR,  placing  some  in  the  Spongiophytaceae  and 
some  in  a second  family,  the  Bitelariaceae.  Bitelarian  cuticles  reflect  distinct  ‘cell’  patterns 
interpreted  by  the  Istchenkos  as  a meristoderm  (without  a cuticle)  and  by  Johnson  and  Gensel 
(1989)  as  a cuticular  epithelium.  A number  of  other  characters  such  as  branching  pattern  and 
presence  of  vascular  tissue  in  Bitelaria,  further  distinguish  bitelarians  from  all  thalli  placed  in  the 
Spongiophytaceae,  as  summarized  in  Johnson  (1989)  and  Johnson  and  Gensel  (1987,  1989). 

Istchenko  and  Istchenko  (1981)  assigned  the  Voronezh  fossils  to  several  genera  ( Orestovia , 
Orestovites,  Voronejipliyton,  Rhytidophyton , Bitelaria  and  Donotela ) relating  them  to  the  algae.  They 
interpreted  the  protruding  round  pores  found  on  thalli  of  the  first  four  genera  as  reproductive 
structures  (termed  capsules)  reminiscent  of  conceptacles  or  nemathecia,  as  found  in  brown  and  red 
algae.  When  mature,  each  structure  supposedly  opened  and  released  its  contents,  leaving  behind  a 
pore.  The  same  structures  in  Orestovia  appear  to  us  very  like  sunken  stomata  or  in  some  cases  like 


GENSEL  ET  AL.:  CANADIAN  EMSIAN  SPONGIOPH  YTON 


165 


the  dark  bodies  or  ‘grossorgane’  of  Krausel  and  Venkatachala  (1966).  No  evidence  of  ‘capsules' 
or  stomata  exists  for  the  Canadian  Spongiophyton. 

Rhytidophyton  superficially  seems  most  similar  to  Spongiophyton  but  apparently  consists  of 
radially  symmetrical  tubular  thalli  with  pronounced  vertical  folding.  The  thalli  are  up  to  0-6  cm  wide 
and  dichotomize,  with  the  resultant  branches  forming  a U-shaped  pattern.  One  or  more 
hemispherical  protuberances  1 -5—3-5  mm  in  diameter  occur  just  below  the  dichotomy,  or  singly 
elsewhere  on  the  thallus,  which  when  lost  form  large  pores.  Capsules  (or  the  oval  apertures  that 
remain  after  their  disintegration)  are  irregularly  distributed  on  the  thallus  surface.  The  thallus  is 
interpreted  as  consisting  of  an  outer  cuticle,  a middle  fibrous  zone,  and  an  inner  region  of  coal. 
Voronejiphyton  Istchenko  and  Istchenko  (1981),  based  on  a few  specimens,  is  very  similar  to 
Rhytidophyton , apparently  differing  in  exhibiting  occasional  longitudinal  ridges  and  internal  wall 
thickening.  In  addition  to  lacking  ‘capsules’,  Spongiophyton  lacks  obvious  folds  and  exhibits  a 
single-layered  thick  cuticle.  Its  short  vertical  branches  usually  are  more  extensively  developed  or 
larger  than  those  of  Rhytidophyton  and  are  not  located  at  points  of  branching. 

Orestovites  is  similar  to  Orestovia , differing  only  in  rather  minor  features,  such  as  the  presence  of 
several  cuticle  layers,  hemispherical  structures,  major  cracks  in  the  cuticle  and  an  irregular  pattern 
of  cells  on  the  inner  cuticle  surface. 

Other  thalloid  Devonian  plants 

Chaloner  et  al.  (1974)  compared  Spongiophyton  with  several  other  Devonian  plants  of  thalloid 
construction  but  with  one  or  more  features  attributed  to  land  plants,  e.g.  Prototaxites , Parka , 
Protosalvinia  and  Nematothallus.  They  all  differ  in  apparently  lacking  the  type  of  tubular 
cuticularized  thallus  plus  pores  seen  in  Spongiophyton , Orestovia  and  Auculeophyton  and  detailed 
comparison  of  most  of  them  is  unnecessary.  It  is  intriguing  to  note,  however,  that  the  vertical 
branches  of  the  Canadian  Spongiophyton  resemble  the  proposed  reconstruction  of  Protosalvinia  by 
Niklas  and  Phillips  (1976)  even  though  many  differences  between  the  two  taxa  exist,  including  their 
postulated  mode  of  growth  (Niklas  and  Chaloner  1976).  Reproductive  structures  are  known  for 
Protosalvinia. 

The  several  types  of  isolated  cuticles  attributed  to  Nematothallus  (sensu  Edwards  1982)  or 
Cosmochlaena  (Edwards  1986)  have  been  compared  at  times  with  Spongiophyton  or  other 
spongiophytes.  These  latter  plants  differ  from  Nematothallus , as  stated  by  Edwards  (1982),  in  their 
tubular  construction  and  apparently  parenchymatous  cell  structure.  Further,  the  isolated 
nematophyte  cuticles  are  not  as  thick  as  those  of  Spongiophyton  and  some  related  taxa.  The  original 
concept  of  Nematothallus  was  of  a system  of  tubes  covered  on  the  upper,  and  perhaps  lower,  surface 
by  a cuticle  and  possibly  bearing  spores  among  the  tubes.  Edwards  suggested  the  nearly  isodiametric 
cell  outlines  of  the  associated  cuticles  represented  outlines  of  filament  tips.  This  taxon,  and 
Prototaxites , served  as  the  basis  for  Lang’s  Nematophytales  (Lang  1937).  While  he  suggested  other 
taxa  may  be  included  in  that  group,  later  research  has  shown  several  of  them  to  be  differently 
constructed.  We  agree  with  Edwards  (1982)  that  Spongiophyton  probably  had  a parenchymatous 
organization,  which  would  contrast  strongly  with  the  above  taxa.  We  also  believe  the  term 
nematophyte  should  be  restricted  to  plants  of  tubular  (filamentous)  construction  as  originally 
proposed  by  Lang,  thus  excluding  Protosalvinia , the  Spongiophytaceae,  and  probably  several  other 
enigmatic  early  land  plants  (Strother  1988). 

Proposed  growth  habit 

The  extensively  preserved  Canadian  Spongiophyton  provides  a basis  for  modifying  concepts  of  its 
growth  habit.  The  dorsiventral,  probably  cross-sectionally  elliptical,  tubular  nature  of  thallus  lobes 
is  confirmed.  Profuse  branching,  both  in  the  same  plane  and  at  right  angles,  produces  a growth  form 
recalling  that  of  some  thallose  liverworts  such  as  Conocephalum  or  Marchantia.  This  extensive 
branching  is  not  consistent  with  or  feasible  to  the  growth  model  proposed  by  Niklas  and  Chaloner 
(1976)  based  on  studies  of  S’,  nanum.  Whether  S.  minutissimum  actually  grew  differently  from  5. 
nanum  is  unclear;  certainly  data  concerning  multidimensional  branching  were  sparse  at  the  time  the 
model  was  proposed. 


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PALAEONTOLOGY,  VOLUME  34 


These  specimens  are  found  in  fluvial  sediments,  some  appearing  more  extensively  transported 
than  others.  Their  habitat  may  have  been  similar  to  that  of  many  extant  thallose  liverworts  - stream 
or  pond  margins  on  a flood  plain.  They  probably  formed  mats  or  stands  several  centimetres  to  tens 
of  centimetres  broad.  The  stacks  of  thalli  found  at  the  Athoville  locality  document  that  several  levels 
of  branches  may  occur  on  a single  organism,  as  if  the  older  portions  were  partially  buried  and  newly 
produced  ones  grew  upwards  (towards  light?).  Where  thalli  have  been  sectioned  in  situ  in  the 
matrix,  the  thicker  (presumably  upper)  surface  is  commonly  uppermost  in  the  rock,  but  not 
consistently  enough  to  support  the  possibility  of  the  plants  growing  within  the  environment  of 
deposition.  The  short  vertical  branches  appear  different  from  other  thallus  lobes,  but  perhaps  they 
elongated  and  became  more  parallel  to  the  main  thallus  when  older,  as  suggested  by  the  specimen 
illustrated  in  Text-figures  2e  and  4k,  n.  Variation  in  branching  and  thallus  orientations  are  depicted 
in  the  reconstruction  in  Text-figure  6. 


text-fig.  6.  Proposed  reconstruction  of  Spongiophyton  minutissumum  plants. 


The  question  of  affinities 

Despite  the  abundance  and  variety  of  specimens  of  S.  minutissimum,  many  questions  remain 
particularly  on  the  nature  of  its  reproductive  structures  and  whether  or  not  it  possessed  conducting 
tissues.  This  has  important  bearing  on  its  affinities  - particularly  in  relation  to  whether  it  represents 
an  ‘algal’  grade  of  organization  or  one  more  comparable  with  embryophytes.  It  appears  to  be  a 
non-vascular  plant  with  a resistant  cuticle  and  pores. 

A resistant  cuticle  is  generally  regarded  as  an  adaptation  to  a terrestrial  habitat,  since  only 
terrestrial  higher  plants  ( = embryophytes)  are  known  to  possess  one.  Mishler  and  Churchill  (1984, 


GENSEL  ET  AL.:  CANADIAN  EMSIAN  SPONGIOPH  YTON 


167 


1985)  and  others  have  postulated  that  a cutin-containing  cuticle  is  a synapomorphy  of  the 
embryophyte  clade.  This  might  be  further  tested  by  chemical  analysis  of  the  cuticles  of  several  plant 
types,  including  representatives  of  the  charophyte-embryophyte  clade,  representatives  of  other  algal 
clades  that  possess  an  outer  covering,  and  of  the  enigmatic  types  discussed  above.  If  lipid-rich 
(cutin-containing)  cuticles  occur  only  in  the  embryophytes,  and  if  Spongiophyton  cuticles  have  a 
similar  composition,  then  one  could  place  it  in  that  lineage.  The  same  might  be  true  of  Orestovia 
or  other  taxa  of  enigmatic  affinity. 

Thus,  although  the  thalloid,  presumed  parenchymatous  construction  of  Spongiophyton  has  led 
workers  to  suggest  it  is  related  to  algae,  one  could  also  envision  it  representing  an  algal-derived  form 
that  had  not  yet  attained  the  grade  of  complexity  of  bryophytes  or  vascular  plants.  Its  affinity  to 
the  charophyte-embryophyte  clade  sensu  Mishler  and  Churchill  (1984,  1985)  remains  uncertain  as 
it  is  possible  that  several  extinct  lineages,  derived  from  any  of  several  algal  clades,  may  have  become 
adapted  for  terrestrial  existence  and  possessed  a resistant  cuticle.  More  fossils  of  these  enigmatic 
types,  and  careful  analysis  of  all  aspects  of  morphology  and  chemistry,  might  address  these 
questions.  Documenting  all  combinations  of  adaptations  to  a terrestrial  existence  among  Silurian- 
Devonian  plants  promises  to  reveal  more  fully  the  intricate  story  of  invasion  of  the  land  by  plants 
and  of  diversity  of  lineages  at  that  time. 


Acknowledgements.  The  authors  thank  Susan  Whitfield,  Staff  Arist,  Biology  Department,  University  of  North 
Carolina  at  Chapel  Hill,  for  making  the  line  drawings  and  reconstruction  and  Mr  Graham  Lawes,  Biology 
Department,  Royal  Holloway  and  Bedford  New  College  for  help  in  preparing  sections  and  TEM  photos. 
Appreciation  is  extended  to  Dr  Robert  Carroll  and  Ms.  Delice  Allison  for  facilitating  the  loan  of  specimens 
from  the  Dawson  collection  at  the  Redpath  Museum,  Montreal,  Canada.  This  research  was  supported  by  NSF 
grants  DEB  80-1 1705,  BSR  83-15670,  and  BSR  8800432  to  Patricia  G.  Gensel. 


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and  Phillips.  T.  L.  1976.  Morphology  of  Protosalvinia  from  the  Upper  Devonian  of  Ohio  and  Kentucky. 
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sommer.  F.  w.  1959.  Spongiophylates,  una  nova  ordem  de  talofitos,  de  classe  fossile  dos  algomycetes.  Ana  is  de 
la  Academia  brasileira  de  Ciencias,  31,  43. 

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P.  G.  GENSEL 

Department  of  Biology  CB  no.  3280 
University  of  North  Carolina 
Chapel  Hill 
N.C.  27599-3280 

W. G. CHALONER 

Department  of  Biology 
School  of  Life  Sciences 
Royal  Holloway  and  Bedford  New  College 
Egham.  Surrey  TW20  0EX 

W.  H.  FORBES 

Department  of  Geology 
University  of  Maine  at  Presque  Isle 
Presque  Isle 
Maine  04769 


Typescript  received  20  October  1988 
Revised  typescript  received  12  February  1990 


TEUTHID  CEPHALOPODS  FROM  THE  UPPER 
JURASSIC  OF  ANTARCTICA 

by  PETER  DOYLE 


Abstract.  Two  teuthid  cephalopods,  Trachyteuthis  cf.  hastiformis  (Riippell)  and  muensterellid  gen.  et  sp.  nov., 
are  described  from  the  Nordenskjold  Formation  (Upper  Jurassic)  of  the  northeastern  Antarctic  Peninsula. 
These  specimens,  the  only  recorded  teuthids  from  Gondwana,  are  closely  related  to  European  species  and 
suggest  a more  widespread  distribution  in  the  Late  Jurassic  than  was  previously  known. 

Dur  ing  the  Antarctic  summer  of  1987-1988  two  fossil  teuthid  specimens  were  collected  by  the 
author  from  the  Nordenskjold  Formation,  a late  Jurassic-early  Cretaceous  black  shale  sequence 
exposed  in  the  northeastern  Antarctic  Peninsula  (Text-fig.  1 ).  These  specimens  represent  the  only 
known  teuthids  from  any  of  the  Gondwana  continents,  and  as  such  are  of  importance  to  our 
understanding  of  teuthid  distribution. 

Teuthids  ( = Vampyromorpha  of  Bandel  and  Leich  1986  and  Engeser  19886)  are  rare  fossils  given 
the  relative  abundance  of  other  fossil  cephalopods  (ammonites  and  belemnites).  A survey  of  the 
teuthid  fossil  record  shows  that  these  cephalopods  are  most  commonly  preserved  in  fine-grained 
sediments  deposited  under  anoxic  or  otherwise  restricted  conditions,  and  the  present  specimens  are 
no  exception.  Lower  Jurassic  specimens  are  commonest,  especially  from  the  widespread  Toarcian 
black  shales  of  Europe  (Posidonienschiefer,  Jet  Rock,  e.g.  see  Riegraf  et  al.  1984;  Engeser  19886; 
and  Doyle  1990  for  summaries),  and  North  America  (Fernie  Formation,  e.g.  Hall  1985;  Hall  and 
Neuman  1989).  Exceptionally  well  preserved  specimens  are  also  known  from  the  Middle  Jurassic 
(Callovian)  Oxford  Clay  of  England  (e.g.  Donovan  1983),  and  similar-aged  anoxic  sediments  in  the 
Ardeche,  France  (Fischer  and  Riou  1982).  Upper  Jurassic  teuthids  are  well  represented  in  the 
Solenhofen  Limestone  of  southern  West  Germany  (Crick  1896;  Bandel  and  Leich  1986;  Engeser 

1986)  and  in  the  Kimmeridge  Clay  of  England  (Owen  1855;  Hewitt  and  Wignall  1988).  Cretaceous 
restricted  facies  have  also  yielded  teuthids:  from  the  Lower  Aptian  ‘Tock’  of  northern  West 
Germany  (Engeser  and  Refiner  1985),  the  Santonian  Fish  Bed  of  the  Lebanon  (Woodward  1883; 
Roger  1946;  Engeser  and  Reitner  1986),  and  the  Upper  Cretaceous  Niobrara  Formation  (Kansas) 
and  Pierre  Shale  (Manitoba)  of  North  America  (e.g.  Miller  and  Walker  1968;  Nicholls  and  Isaak 

1987) . 

The  relative  paucity  of  teuthid  specimens  has  lead  to  an  anomalous  distribution  pattern.  Thus, 
apart  from  the  specimens  found  in  anoxic  sediments  in  the  United  States,  Cuba  (Schevill  1950),  the 
Lebanon,  and  the  Cape  Verde  Islands,  West  Africa  (Reitner  and  Engeser  1982),  the  majority  of 
specimens  are  from  Europe  (see  Engeser  19886).  Prior  to  the  present  study,  teuthids  were  unknown 
from  Gondwana,  as  the  only  record  from  Queensland,  Australia  (Moore  1870)  has  been  found  to 
be  an  indeterminate  bivalve  fragment  (Engeser  and  Phillips  1986).  The  purpose  of  this  paper  is  to 
document  the  new  record  and  discuss  its  implications  for  palaeobiogeography. 


GEOLOGICAL  SETTING 

From  late  Jurassic  to  early  Tertiary  times  the  northern  Antarctic  Peninsula  was  an  active  volcanic 
arc  formed  by  the  southeastward  subduction  of  the  proto-Pacific  plate.  During  subduction,  a 
5-6  km  thick  sedimentary  sequence  was  deposited  in  a retro-arc  basin  (the  Larsen  Basin)  to  the  east 
of  the  arc.  The  Nordenskjold  Formation  is  a distinctive  sequence  of  air-fall  ashes  and  black 


| Palaeontology,  Vol.  34,  Part  1,  1991,  pp.  169—178-1 


© The  Palaeontological  Association 


170 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  1.  Locality  map  for  the  northeastern  Antarctic  Peninsula,  showing  the  distribution  of  known 
Nordenskjold  Formation  exposures.  The  specimens  described  below  were  collected  from  the  type  locality  at 

Longing  Gap. 


mudstones  of  late  Jurassic  to  early  Cretaceous  age  which  is  thought  to  form  the  base  of  the  Larsen 
Basin  succession  (Macdonald  et  al.  1988).  The  Nordenskjold  Formation  is  exposed  at  five  localities 
along  the  northeastern  coast  of  the  Antarctic  Peninsula  (Farquharson  1983;  Text-fig.  1),  and  its 
stratigraphy  has  recently  been  revised  by  Whitham  and  Doyle  (1989). 

Two  members  are  recognized  within  the  Nordenskjold  Formation  at  Longing  Gap,  the  type 
locality  for  the  formation  (Text-fig.  1).  The  Longing  Member  ranges  in  age  from  Kimmeridgian  to 
Tithonian  and  is  dominated  by  parallel-laminated  black  mudstones  with  subordinate,  thin  ash 
layers.  The  Ameghino  Member  ranges  in  age  from  Tithonian  to  Berriasian  and  is  characterized  by 
structureless  mudstones  and  thicker  ash  layers  (Whitham  and  Doyle  1989).  A detailed 
sedimentological  study  of  the  Nordenskjold  Formation  is  currently  being  carried  out  by  Dr  A.  G. 
Whitham  (British  Antarctic  Survey). 

Both  teuthid  specimens  were  obtained  from  near  the  top  of  the  Longing  Member  at  Longing  Gap. 
They  were  associated  with  a fauna  consisting  of  the  ammonites  Virgatosphinctes  spp.  and 
Lithacoceras  sp.,  and  the  bivalves  Retroceramus  spp.  and  Arctotis  sp.,  of  Tithonian  age  (Whitham 
and  Doyle  1989).  Sedimentological  (parallel  lamination,  etc.)  and  palaeoecological  (low  faunal 
diversity,  a lack  of  true  benthos  and  trace  fauna)  indices  show  that  the  Longing  Member  was 
deposited  under  low  oxygen,  anaerobic  to  episodically  dysaerobic  conditions  (Doyle  and  Whitham 
in  press).  Although  the  Longing  Member  fauna  had  a primarily  pelagic  or  pseudoplanktonic  mode 
of  life,  the  teuthids  were  collected  from  an  interval  with  some  benthic  colonization,  though  lacking 


DOYLE:  ANTARCTIC  TEUTHID  CEPHALOPODS 


171 


bioturbation,  suggesting  dysaerobic  rather  than  the  anaerobic  zone  conditions  characteristic  of  the 
lower  part  of  the  member  (Doyle  and  Whitham  in  press). 


SYSTEMATIC  PALAEONTOLOGY 

The  terminology  used  below  is  discussed  in  detail  in  Jeletzky  (1966),  and  the  classification  largely 
follows  that  of  Engeser  ( 19886)  (see  discussion  below).  Both  specimens  are  housed  in  the  collections 
of  the  British  Antarctic  Survey  (BAS)  in  Cambridge.  Comparative  material  was  examined  in  the 
British  Museum  (Natural  History)  (BMNH),  London.  Annotation  of  synonymy  lists  follows  the 
convention  of  Matthews  (1973). 


Subclas  coleoidea  Bather,  1888 
Order  teuthida  Naef,  1916 

Remarks.  Jeletzky  (1966)  employed  the  order  Teuthida  Naef,  1916  for  all  known  fossil  squid. 
However,  Bandel  and  Leich  (1986)  studied  in  detail  specimens  of  the  Solenhofen  teuthids 
Leptoteuthis,  Plesioteuthis  and  Trachyteuthis , and  concluded  that  they  possessed  only  eight  arms, 
linked  by  basal  webs,  and  were  therefore  most  closely  related  to  the  Recent  cephalopod 
V ampyroteuthis . This  lead  to  the  adoption  of  the  order  Vampyromorpha  Robson,  1929  for  all  fossil 
‘teuthids’  by  Berthold  and  Engeser  (1987),  Engeser  and  Bandel  (1988)  and  Engeser  (19886),  and  the 
contention  that  the  fossil  ‘teuthids’  were  not  directly  ancestral  to  the  Recent  Teuthida.  The  more 
conservative  usage  of  the  order  Teuthida  Naef,  1916  is  maintained  below,  however,  as  the  specimens 
discussed  below  shed  no  further  light  on  this  discussion. 

Suborder  mesoteuthina  Naef,  1921 
Family  trachyteuthididae  Naef,  1921 
Genus  trachyteuthis  Meyer,  1846 

(=  Coccoteuthis  Owen,  1855,  Voltzia  Schevill,  1950;  junior  subjective  synonyms) 

Type  genus.  Sepia  hastiformis  Riippell,  1829,  by  subsequent  designation  (Bulow-Trummer  1920,  p.  248). 
Diagnosis.  See  Naef  (1922,  p.  137). 

Remarks.  The  form  of  Trachyteuthis , and  its  relative  similarity  to  the  present-day  cuttlebone  of 
Sepia  officianalis , has  led  some  authors  to  consider  that  this  genus  is  actually  representative  of  the 
Sepiida  rather  than  the  Teuthida.  Schevill  (1950)  described  a new  genus  from  the  Oxfordian  of 
Cuba,  Voltzia , which  he  considered  distinct  from  Trachyteuthis , as  it  apparently  possessed 
‘phragmocone  deposits’  similar  to  those  of  Sepia.  Donovan  (1977)  questioned  the  distinction  of  the 
nominal  genera  Voltzia  and  Trachyteuthis , but  went  further  in  suggesting  that  Trachyteuthyis  was 
a true  sepiid,  attributing  the  lack  of  phragmocone  to  solution  of  the  delicate  aragonite  plates  after 
burial.  In  one  specimen  of  Trachyteuthis  from  Solenhofen  (BMNH  83730),  Donovan  reported 
fragments  attributable  to  phragmocone  debris  as  a ‘lag’  beneath  the  shell  After  sectioning,  I found 
that  this  specimen  revealed  no  further  debris  beneath  the  dorsal  shield,  and  no  indication  of  an 
extensive  phragmocone  development,  and  as  such  this  evidence  is  not  unequivocal.  No  traces  of 
phragmocone  were  found  in  the  Antarctic  specimen,  which  is  preserved  as  a thin  shield  < 1 mm 
thick,  built  of  successive  lamellae.  An  ink  sac  is  present  in  this  specimen,  and  though  slightly 
displaced,  it  is  found  directly  beneath  the  thin  gladius,  without  any  trace  of  intervening 
phragmocone  plates. 

Hewitt  and  Wignall  (1988)  have  studied  the  mineralogy  of  Trachyteuthis  specimens  from  the 
English  Kimmeridge  Clay,  and  have  determined  that  its  original  mineralogy  was  francolite,  rather 
than  aragonite.  These  authors  used  this  as  additional  evidence  against  sepiid  affinities  of 
Trachyteuthis , arguing  that  one  would  expect  a sepiid  ‘cuttlebone’  to  be  aragonitic,  rather  than 


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PALAEONTOLOGY,  VOLUME  34 


phosphatic.  The  Antarctic  specimen  described  below  is  also  phosphatic,  but  the  possibility  of 
diagenetic  replacement  of  original  aragonite  cannot  be  ruled  out,  especially  since  specimens  of  the 
thin-shelled  ammonite  Haploceras  and  belemnoid  ? Belemnoteuthis  (both  originally  aragonitic)  are 
found  as  crushed,  phosphatic  films  in  the  Nordenskjold  Formation. 

In  summary,  it  seems  probable  that  despite  the  close  morphological  similarities  between  the  shells 
of  Trachyteuthis  (=  Voltzia)  and  Sepia,  the  absence  of  a proven  phragmocone  and  the  possible 
original  phosphate  shell  mineralogy  of  the  former  suggest  that  assignment  to  the  Teuthida  rather 
than  to  the  Sepiida  is  more  correct. 

Range.  Definite  records  from  the  Lower  Oxfordian  to  Tithonian  of  southern  West  Germany  (Bavaria), 
England  (Dorset,  North  Yorkshire),  USSR  (Volga  region),  Cuba  (Vinales  region)  and  Antarctica  (Graham 
Land).  A single  doubtful  record  from  the  Lower  Aptian  of  northern  West  Germany  (Heligoland). 


cf.  *1829 
cf.  v.  1855 
cf.  v . 1 896 
cf.  1 922 
cf.  v.  1977 
cf.  v.  1988a 
cf.  19886 
v. 1988 


Trachyteuthis  cf.  hastifonnis  ( Ruppell,  1829) 

Text-figs  2a,  b and  4 

Sepia  hastifonnis  Ruppell,  p.  9,  pi.  3,  fig.  2. 

Coccoteuthis  latipinnis  Owen,  p.  124,  pi.  7. 

Coccoteuthis  hastifonnis  Ruppell;  Crick,  p.  439,  pi.  14. 

Trachyteuthis  hastifonnis  (Ruppell);  Naef,  p.  137,  text-fig.  51. 

Trachyteuthis  sp.  Donovan,  p.  32,  text-figs  8 and  9. 

Trachyteuthis  hastifonnis  (Ruppell);  Engeser,  p.  82,  text-fig.  lc. 

Trachyteuthis  hastifonnis  ( Ruppell);  Engeser,  p.  59.  [Full  and  extensive  synonymy  given], 
lossil  teuthid;  Anonymous,  p.  15,  text-fig.  6.  [Colour  photograph  of  specimen  described 
below]. 


Type  specimen  (of  Trachyteuthis  hastifonnis).  Holotype,  Senckenberg  Museum,  Frankfurt-am-Main,  register 
number  XI  1328.  Lower  Tithonian,  Solenhofen  Limestone,  Miihlheim,  Bavaria,  West  Germany. 

Material.  One  specimen,  BAS  D. 9007. 33,  uppermost  Longing  Member,  Nordenskjold  Formation  (Whitham 
and  Doyle  1989,  p.  6).  Longing  Gap,  Graham  Land,  Antarctic  Peninsula.  Preserved  intact  in  a carbonate 
concretionary  horizon  yielding  the  ammonite  Virgatosphinctes  rotundidoma  Uhlig  of  Tithonian  age  (Whitham 
and  Doyle,  1989,  text-fig.  6/). 

Description.  The  single  specimen  collected  comprises  the  majority  of  the  median  field  of  a small  (total  preserved 
length  90-5  mm)  Trachyteuthis  gladius.  It  is  preserved  in  a carbonate  concretion  allowing  three-dimensional 
preservation,  in  a formation  that  otherwise  yields  compressed  fossils.  The  specimen  consists  of  two  parts, 
naturally  split  by  freeze-thaw  action.  These  represent  ventral  and  dorsal  surfaces  of  the  gladius  divided  cleanly 
along  shell  lamellae,  the  two  parts  united  are  less  than  1 mm  thick. 

The  dorsal  fragment  (Text-fig.  2b)  is  the  most  recognizable  of  the  two  as  Trachyteuthis.  It  exhibits  (in 
negative,  as  it  is  the  undersurface  of  the  topmost  part  of  the  gladius)  a median  field  with  a narrow  (width 
23-4  mm)  central  region  composed  of  a series  of  closely  spaced  pustules  arranged  in  arcuate  arrays  which 
correspond  to  growth  lines.  A central  ridge  or  median  keel  is  present.  The  median  field  is  completed  by 
relatively  smooth  lateral  areas  (‘  Seiteplatte'  of  Naef  1922,  text-fig.  51).  These  are  incomplete,  but  display  some 
longitudinal  striation.  Finally,  there  are  displaced  fragments  of  a probable  wing  present  at  the  left  posterior 
of  the  shell. 

The  ventral  fragment  (Text-fig.  2a)  is  less  easily  recognizable  as  representative  of  Trachyteuthis , as  there  are 
no  pustules  or  definable  field  areas  present.  The  fragment  consists  of  an  almost  smooth  shield  with  some  traces 
of  arcuate  growth  lines  in  the  central  area.  Part  of  the  lateral  area  of  the  median  field  is  definable  in  the  right 
anterior  of  the  specimen,  and  fragments  of  a wing  in  the  left  posterior.  This  portion  of  the  gladius  very  clearly 
shows  the  lamellar  construction  of  the  gladius  and,  where  successive  lamellae  have  exfoliated,  neither  it  nor  the 
underlying  matrix  displays  any  evidence  of  phragmocone  deposits.  The  presence  of  an  ink  sac  is  indicated  by 
a dull  black  mass  up  to  5 mm  thick  beneath  the  ventral  portion  of  the  gladius  in  the  right  posterior  of  the 
fragment  (Text-fig.  2a). 


DOYLE:  ANTARCTIC  TEUTHID  CEPHALOPODS 


173 


text-fig.  2.  Trachyteuthis  cf.  hastiformis  (Riippell).  Specimen  D. 9007. 33,  Tithonian,  Longing  Member, 
Nordenskjold  Formation,  Longing  Gap.  Ventral  and  dorsal  fragments  of  naturally  split  gladius,  x 1.  a,  ventral 
fragment  showing  the  ink  sac  beneath  the  thin  lamellae  of  the  shell,  b,  dorsal  fragment  showing  the  characteristic 
pustules  of  the  median  field.  Abbreviations:  MA,  median  asymptote;  MF,  median  field;  MK,  median  keel;  Sp, 
1 Seiteplatte' ; W,  wing.  A reconstruction  of  the  gladius  is  given  in  Text-figure  4. 


Remarks.  This  specimen  is  clearly  representative  of  the  genus  Trachyteuthis , and  is  very  close  to 
specimens  from  the  Kimmeridge  Clay  of  England  and  the  Solenhofen  Limestone  of  West  Germany. 
However,  its  small  size,  which  may  indicate  that  it  is  a juvenile,  and  its  incomplete  preservation, 
allow  only  tentative  assignment  to  the  species  Trachyteuthis  hastiformis  (Riippel).  Trachyteuthis 
palmeri  (Schevill)  (Lower  Oxfordian,  Cuba)  and  T.  zhuravlevi  Hecker  and  Hecker  (Lower  Volgian, 
Volga  region,  USSR)  are  poorly  known,  and  differ  only  in  their  greater  width  and  elongate  form, 
respectively. 


Suborder  kelaenina  Starobogatov,  1983 
Family  muensterellidae  Roger,  1952 
munsterellid  gen.  et  sp.  nov. 

Text-figs  3a,  b and  4 

Material.  A single  specimen,  BAS  D. 9008. 3,  found  loose  in  the  uppermost  Longing  Member  (approximately 
equivalent  horizon  to  BAS  D. 9007. 33),  Nordenskjold  Formation.  Longing  Gap,  Graham  Land,  Antarctic 
Peninsula.  Associated  Virgatosphinctes  and  Retroceramus  specimens  indicate  a Tithonian  age. 


174 


PALAEONTOLOGY,  VOLUME  34 


Description.  The  specimen  consists  of  a gladius  with  a preserved  length  of  82.5  mm,  comprising  a broad  spoon- 
shaped conus  with  a rhachis  extending  anteriorly  from  it  (Text-fig.  3a). 

The  spoon-shaped  conus  is  incomplete,  but  has  an  approximate  maximum  width  of  37  mm.  It  is  preserved 
flattened  with  no  indications  of  concentric  or  other  growth  lines  upon  its  dorsal  surface.  The  median  field  of 
the  gladius  is  developed  as  a rhachis,  commencing  as  a median  ridge  or  raised  area  in  the  posterior  of  the 
gladius,  then  extending  anterior  of  the  conus.  The  median  field  is  completed  by  smooth  lateral  outgrowths 
('  Seiteplatte')  which  accompany  the  rhachis  for  half  of  its  length  and  up  to  60  mm  of  the  total  length  of  the 
gladius,  and  indistinct  surface  features  on  the  conus  indicate  the  possible  position  of  the  median  asymptotes 
which  border  the  median  field  (Text-fig.  4). 

The  rhachis  diverges  anteriorly  at  an  angle  of  approximately  5°,  and  expands  to  a maximum  width  of  4 mm. 
As  the  rhachis  expands,  it  divides  anteriorly  from  its  original  raised  area  on  the  conus  to  produce  two  laterally 
placed  ridges  with  an  intervening,  smoother  area.  There  is  some  indication  of  a weak  median  keel  in  the  centre 
of  this  region,  but  preservation  is  too  poor  for  this  to  be  unequivocal. 


text-fig.  3.  Muensterellid  gen.  et  sp.  nov.  Specimen  D. 9008. 3,  Tithonian,  Longing  Member,  Nordenskjold 
Formation,  Longing  Gap.  a,  dorsal  view  of  gladius  x 1.  b,  sketch  representation  of  same  view,  xl. 
Abbreviations:  C,  conus;  FR,  free  rhachis;  Pr,  preparation  marks;  Sp,  ‘ Seiteplatte A reconstruction  of  the 

gladius  is  given  in  Text-figure  4. 


Remarks.  The  unusual  divided  form  of  the  rhachis,  and  apparent  absence  of  growth  lines  in  this 
specimen,  initially  gave  rise  to  doubts  about  its  actual  cephalopod  affinities.  However,  despite  this, 
the  regular  form  of  the  conus  and  its  relationship  with  the  rhachis  confirm  that  this  specimen 
undoubtedly  represents  a (new)  teuthid  taxon,  and  it  is  certainly  not  representative  of  any  known 
non-cephalopod  mollusc,  plant  (cf.  Engeser  and  Phillips  1986)  or  even  fish  (P.  Forey,  pers.  comm. 
1987). 


DOYLE:  ANTARCTIC  TEUTHID  CEPHALOPODS 


175 


The  form  of  the  specimen  discussed  most  closely  resembles  taxa  of  the  Muensterellidae 
(Kelaenina).  Specifically,  the  presence  of  a ‘free  rhachis’  distinguishes  it  from  otherwise  similar 
specimens  of  Palaeololigo  Naef  (Palaeologinidae,  Mesoteuthina),  which  have  a broader  median 
field.  Of  the  Muensterellidae,  the  Tithonian  genera  Listroteuthis  Naef  and  Muensterella  Schevill  are 
closest,  especially  the  former  which  has  a similar  conus  shape.  The  only  other  muensterellid  with 
a divided  rhachis  is  the  Campanian  form  Tusoteuthis  Logan  (=  Kansasteuthis  Miller  and  Walker; 
see  Nicholls  and  Isaak  1987,  p.  734).  The  gladius  of  Tusoteuthis  has  a leaf-shaped  conus  with  a 
robust  ‘free  rhachis'  starting  immediately  from  its  anterior.  The  rhachis  does  not  diverge 
significantly  to  the  anterior,  and  is  much  more  robust  than  that  of  the  present  specimen.  Difference 
of  rhachis  design  in  otherwise  similar  spoon-shaped  gladii  of  Recent  squid  was  noted  by  Toll  (1988), 
illustrating  the  potential  for  variability  in  this  feature.  The  rhachis  of  the  Recent  family 
Bathyteuthidae  would  seem  to  be  analogous  to  the  Antarctic  specimen,  having  lateral  rods  joined  by 
a central  U-shaped  area. 

The  only  Prototeuthina  which  approaches  the  present  specimen  is  the  genus  Maioteuthis  Reitner 
and  Engeser  (Plesioteuthididae).  Maioteuthis  has  a much  reduced  conus  and  an  extremely  long  and 


Trachyteuthis  Muensterellid 

text-fig.  4.  Suggested  reconstructions  of  the  Antarctic  teuthids,  not  to  scale.  Trachyteuthis  redrawn  after  Naef 
(1922,  fig.  51).  Abbreviations:  C,  conus;  LA,  lateral  asymptote;  MA,  median  asymptote;  MF,  median  field; 

MK,  median  keel;  Sp,  ‘ Seiteplatte' ; W,  wing. 


176 


PALAEONTOLOGY,  VOLUME  34 


narrow  median  field  which  divides  anteriorly  to  present  a weak  median  keel  (Reitner  and  Engeser 
1982,  text-fig.  2).  The  Antarctic  specimen  resembles  Maioteuthis  only  in  having  a divided  median 
field  with  a faintly  developed  median  keel,  but  differs  greatly  in  possessing  a spoon-like  conus  with 
an  anteriorly  extensive  ‘free  rhachis’,  demonstrating  its  muensterellid  affinities. 

In  summary,  the  overall  form  of  the  gladius  (conus  and  rhachis)  of  this  specimen  would  support 
the  erection  of  a new  genus  within  the  Muensterellidae.  However,  the  single  specimen  available  does 
not  permit  the  formal  designation  of  a new  taxon. 


PALAEOBIOGEOGRAPHICAL  CONSIDERATIONS 

There  are  too  few  records  to  provide  any  definite  conclusions  about  the  palaeobiogeography  of 
Mesozoic  teuthids.  However,  the  discovery  of  fossil  teuthid  gladii  from  Gondwana  is  significant  in 
illustrating  that  the  present  observed  European  bias  is  artificial,  induced  to  some  extent  by  the 
fragility  of  the  remains  and  a greater  intensity  of  study  in  western  Europe.  Therefore,  some  primary 
observations  are  presented  here. 

In  addition  to  its  European  (England,  West  Germany)  occurrences  (see  Engeser  1 988 A and 
references  therein),  the  genus  Trachyteuthis  is  recorded  from  the  Lower  Volgian  of  the  USSR  (Volga 
region)  (Hecker  and  Hecker  1955),  the  Lower  Oxfordian  of  western  Cuba  (as  Voltzia)  (Schevill 
1950)  and  now  the  Tithonian  of  Antarctica.  The  majority  of  these  specimens  are  remarkably  similar 
to  the  western  European  representatives,  especially  the  Antarctic  example,  suggestive  of  an  almost 
worldwide  distribution  for  Trachyteuthis  in  the  Late  Jurassic,  transgressing  boreal  and  Tethyan 
realm  boundaries  observed  in  other  marine  groups.  Cretaceous  trachyteuthids  are  represented  only 
by  a possible  Trachyteuthis  from  the  Lower  Aptian  of  Heligoland  (northern  Germany)  (Engeser  and 
Reitner  1985)  and  Upper  Cretaceous  records  from  the  Lebanon  (e.g.  Lihanonteuthis  Kretzoi)  and 
North  America  (e.g.  Actinosepia  Whiteaves)  (Engeser  1988/5). 

The  Muensterellidae  have  similarly  disparate  geographical  records.  Muensterella  and  associated 
genera  (i.e.  Listroteuthis  Naef,  Calaenoteuthis  Naef)  are  presently  known  only  from  the  Lower 
Tithonian  of  West  Germany  (see  Engeser  1988/5).  The  Antarctic  muensterellid,  described  from 
sediments  of  similar  age,  has  many  points  in  common  with  these  European  genera,  and  like 
Trachyteuthis,  is  a possible  indicator  of  a formerly  more  widespread  distribution.  Cretaceous 
muensterellids  are  relatively  rare,  but  there  is  some  indication  of  less  centred  distribution  pattern 
than  is  presently  observed.  Thus,  while  Tusoteuthis  (?  = Kansasteuthis,  Niobrarateuthis  and 
Enchoteuthis)  is  only  recorded  from  the  Upper  Cretaceous  of  North  America  (Nicholls  and  Isaak 
1987),  two  undescribed  Australian  teuthid  specimens  with  affinity  to  Tusoteuthis  are  preserved  in  the 
BMNH  collections.  These  specimens,  from  the  Lower  Cretaceous  (Albian)  of  Queensland, 
Australia,  (BMNH  C. 59211,  C. 59276)  resemble  Tusoteuthis,  but  are  larger,  possessing  a ribbed 
conus  and  multiple  grooved  free  rhachis,  and  undoubtedly  represent  a new  taxon. 


Acknowledgements . The  specimens  described  above  were  collected  while  I was  employed  by  the  British 
Antarctic  Survey,  to  which  organization  I extend  my  thanks  for  the  opportunity  to  describe  them.  I gratefully 
acknowledge  assistance  in  the  field  from  Dave  O'Dowd  and  Donny  Stewart.  I thank  my  co-worker  Andy 
Whithanr  for  his  useful  comments  and  discussion. 


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nicholls,  e.  and  isaak,  h.  1987.  Stratigraphic  and  taxonomic  significance  of  Tusoteuthis  longa  Logan 
(Coleoidea,  Teuthida)  from  the  Pembina  Member,  Pierre  Shale  (Campanian),  of  Manitoba.  Journal  of 
Paleontology,  61,  727-737. 

owen,  R.  1855.  Notice  of  a new  species  of  an  extinct  genus  of  dibranchiate  cephalopod  (Coccoteuthis  latipinnis ) 
from  the  Upper  Oolitic  shales  at  Kimmeridge.  Proceedings  of  the  Geological  Society  of  London,  11,  124—125. 
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Paldontologisches  Zeitschrift , 56,  209-219. 

riegraf,  w.,  werner,  G.  and  lorcher,  F.  1984.  Der  Posidonienschiefer . Biostratigraphie,  Fauna  und  Fazies  des 
siidwestdeutschen  Untertoarciums  ( Lias  e).  Enke,  Stuttgart,  195  pp. 

ROGER,  j.  1946.  Les  Invertebres  des  couches  a poissons  du  Cretace  Superieur  du  Liban.  Memoires  de  la  Societe 
Geologique  de  France,  N.S.,  51,  1-92. 

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vol.  2.  Masson,  Paris,  755  pp. 

ruppell,  E.  1829.  Abbildung  und  Beschreibung  einiger  neuen  oder  wenig  bekannten  Versteinerungen  aus  der 
Kalkschieferformation  von  Solnhofen.  Bronner,  Frankfurt  am  Main,  12  pp. 
schevill,  w.  E.  1950.  An  Upper  Jurassic  sepioid  from  Cuba.  Journal  of  Paleontology,  24,  99-101. 
storabogatov,  y.  i.  1983.  The  system  of  the  Cephalopoda.  4-7.  In  storabogatov,  y.  i.  and  nesis,  k.  n.  (eds). 
Taxonomy  and  ecology  of  cephalopods.  Zoological  Institute,  USSR  Academy  of  Sciences,  Leningrad,  77  pp. 
[In  Russian], 

toll,  r.  b.  1988.  Functional  morphology  and  adaptive  patterns  of  the  teuthoid  gladius.  167-182.  In  trueman, 
e.  R.  and  clarke,  M.  R.  (eds).  The  Mollusca,  vol.  11.  Form  and  Function.  Academic  Press,  San  Diego,  504  pp. 
whitham,  a.  G.  and  doyle,  p.  1989.  Stratigraphy  of  the  Upper  Jurassic-Lower  Cretaceous  Nordenskjold 
Formation  of  eastern  Graham  Land,  Antarctica.  Journal  of  South  American  Earth  Sciences.  2,  371-384. 
woodward,  s.  p.  1883.  On  a new  genus  of  fossil  ‘ Calmary  ’ from  the  Cretaceous  formation  of  Sahel-Alma,  near 
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PETER  DOYLE 

Nature  Conservancy  Council 

Typescript  received  25  October  1989  Northminster  House 

Revised  typescript  received  5 March  1990  Peterborough  PEI  1UA,  UK 


A NEW  SCLE R ACTINI AN-LI KE  CORAL  FROM  THE 
ORDOVICIAN  OF  THE  SOUTHERN  UPLANDS, 

SCOTLAND 

by  COLIN  T.  SCRUTTON  and  EUAN  N.  K.  CLARKSON 


Abstract.  New,  discoidal  fossils  preserved  as  moulds  from  the  middle  Ordovician  (Caradoc)  of  the  Southern 
Uplands  are  shown  to  possess  characteristic  coralline  microarchitecture.  They  are  solitary,  zoantharian  corals 
with  cyclic,  hexameral  septal  insertion.  Successive  cycles  are  arranged  in  a system  of  nested  triads  similar  to 
patterns  associated  with  septal  substitution  in  scleractinian  corals.  The  corallum  lacks  tabulae  or  dissepiments 
but  is  epithecate  with  the  point  of  origin  a basal  disc  as  in  Scleractinia  rather  than  a cone  as  in  Rugosa.  The 
new  coral  is  named  Kilbuchophyllum  discoidea  gen.  et  sp.  nov.,  and  is  placed  in  the  new  family 
Kilbuchophyllidae  and  the  new  order  Kilbuchophyllida.  It  is  interpreted  as  an  early  example  of  skeletal 
acquisition  by  the  group  of  anemones  that  ultimately  gave  rise  to  the  Scleractinia  in  the  Middle  Triassic.  The 
phylogeny  of  the  Zoantharia  is  briefly  discussed  in  the  light  of  this  new  material. 

A striking  feature  of  the  geological  distribution  of  fossil  corals  is  the  sequential  ranges  of  the  two 
major  and  crudely  homoeomorphic  groups  possessing  well  developed  septa.  The  Rugosa  appear  in 
the  mid-Ordovician  and  become  extinct  at  the  end  of  the  Permian  (Scrutton  1979,  1988;  Hill  1981), 
whilst  the  Scleractinia  first  occur  in  the  middle  Triassic  and  persist  to  the  present  day  (Wells  1956; 
Oliver  1980).  No  early  Triassic  corals  are  known.  The  fundamental  distinction  between  these  two 
groups  of  corals  lies  principally  in  their  modes  of  septal  insertion,  serial  in  four  quadrants  in  the 
Rugosa,  and  cyclic,  hexameral  in  the  Scleractinia  (Oliver  1980).  Other  zoantharian  corals  occur  in 
the  Palaeozoic  but  are  less  comparable.  The  small,  enigmatic  Devono-Carboniferous  order 
Hexacorallia  is  also  strongly  septate  but  distinct  in  septal  pattern  from  both  Rugosa  and 
Scleractinia  (Hill  1981).  A third  major  group  of  exclusively  Palaeozoic  and  colonial  corals,  the 
Tabulata,  have  variably  and  generally  weakly  developed  septa  for  which  no  definite  pattern  of 
insertion  has  yet  been  established.  Claimed  rugosan  insertion  in  Agetolites  (Kim  1974)  requires 
restudy  before  its  significance  can  be  assessed.  In  addition,  pre-Ordovician  beds  have  yielded  a small 
number  of  coralline  organisms,  one  of  which,  Cothonion , has  well  developed  septa  and  may  derive 
from  the  same  stock  as  the  Rugosa  (Scrutton  1979;  Jell  1984). 

Although  direct  descent  of  the  Scleractinia  from  the  late  Palaeozoic  Rugosa  has  been  claimed  by 
Schindewolf  (1942)  and  others,  the  alternative  view  that  the  Scleractinia  evolved  independently 
from  anemone  precursors  in  the  middle  Triassic  has  been  strongly  argued  by  Oliver  (1980).  Over  the 
years,  a number  of  Palaeozoic  corals  had  been  described  as  exhibiting  scleractinian  characters. 
However,  Hill  (1960)  noted  that  ‘all  Palaeozoic  corals  claimed...  to  be  Scleractinia  have 
subsequently  been  proved  to  be  Rugosa...’.  The  sole  uncertainty  she  allowed  was  the  record  of 
apparent  Permian  age  of  species  of  the  genus  Omphalophyllia  by  Minato  (1955).  This  Japanese 
material  is  too  poorly  preserved  to  be  reliably  interpreted  and  its  restudy  is  required;  Minato  (1955, 
p.  1 80)  considered  the  possibility  that  it  was  related  to  Lophocarinophyllum.  On  the  other  hand,  the 
host  rock  is  now  interpreted  as  an  olistostrome  in  a Triassic  accretionary  complex  containing 
Carboniferous,  Permian  and  Triassic  olistoliths;  thus  there  are  no  positive  data  to  support  Permian 
Omphalophyllia  (Makoto  Kato  pers.  comm.).  The  type  material  of  Omphalophyllia  is  a Triassic 
scleractinian  coral,  considered  a synonym  of  Conophyllia  by  Wells  (1956).  Since  then,  the  possibility 
of  a scleractinian  presence  in  the  Palaeozoic  has  continued  to  be  raised.  Krasnov  (1970)  considered 
Scleractinia  of  fungiid  type  to  have  separated  from  the  Rugosa  in  the  early  to  mid  Palaeozoic  with 

(Palaeontology,  Vol.  34,  Part  1,  1991,  pp.  179-194,  1 pl.| 


© The  Palaeontological  Association 


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PALAEONTOLOGY,  VOLUME  34 


the  Calostylidae  as  the  most  likely  ancestral  group.  However,  Smith  (1930)  had  already  shown 
Calostylis  to  have  rugosan  septal  insertion  and  this  was  confirmed  by  Weyer  (1973).  More  recently, 
Erina  and  Kim  (1980)  considered  the  Ordovician  Sumsarophyllum  and  their  new  genus 
Tjanshanophyllia  to  both  show  fungiid  characteristics  on  the  basis  of  many  cycles  of  perforate  septa 
and  the  reported  lack  of  an  epitheca.  They  did  not  demonstrate  cyclic,  hexameral  septal  insertion, 
however,  which  must  be  considered  the  critical  evidence  for  rejecting  classification  with  the  Rugosa 
and  supporting  comparison  with  the  Scleractinia.  Oliver  (1980)  concluded  at  that  time  that  no 
known  Palaeozoic  coral  demonstrated  cyclic  septal  insertion. 

Thus  we  regard  our  description  here  of  a new  Ordovician  solitary  coral  with  scleractinian 
characteristics  as  the  first  well  documented  case  of  a Palaeozoic  scleractiniamorph.  Our  claim  is 
based  on  a full  assessment  of  the  structure  and  development  of  the  coral,  including  and  principally, 
the  clear  expression  of  hexameral  cyclic  septal  insertion.  We  presuppose  our  conclusions  concerning 
the  nature  of  this  material  and  scleractinian  coral  terminology  is  used  throughout  for  the 
morphological  descriptions  (Wells  and  Hill  1956). 

Abbreviations.  All  material  we  have  collected  is  housed  in  the  Royal  Museum  of  Scotland,  Edinburgh  (RMS). 
Additional  material  referred  to  is  housed  in  the  British  Geological  Survey,  Edinburgh  (BGS)  and  The  Natural 
History  Museum,  Department  of  Zoology,  London  (BM(NH)Z). 


FIELD  OCCURRENCE 

In  the  Southern  Uplands  of  Scotland,  Ordovician  rocks  extend  as  a continuous  belt  from  the  North 
Sea  to  the  Irish  Sea  (Text-fig.  1).  They  are  largely  confined  to  the  Northern  Belt  and  consist  in  the 
main  of  Arenig  volcanics  overlain  by  a suite  of  younger  sediments.  The  oldest  sediments  are 
Llanvirn-Llandeilo  red  and  grey  cherts;  these  are  succeeded  by  black  shales  of  Glenkiln  age  ( gracilis 
and  peltifer  Zones),  overlain  in  turn  by  Caradoc  greywackes,  grits  and  shales.  Whereas  all  these 
sediments  are  typically  of  deep-water  origin,  there  are  a number  of  localities,  referred  to  by  Peach 
and  Horne  (1899),  which  have  yielded  shelly  fossils.  The  best  exposures  are  at  Kilbucho  (National 
Grid  Reference  NT  060338)  and  at  Wallace’s  Cast  in  the  Wandel  Burn  (NT  967263)  (Text-fig.  1). 
Other  occurrences  were  noted  by  Ritchie  and  Eckford  (1935)  westwards  to  Duntercleuch  and  Snar, 
north-west  of  Leadhills. 

At  Kilbucho  and  Wallace’s  Cast,  imperfectly  exposed  though  they  are,  basal  greywackes  are 
overlain  by  a coarse  conglomerate  with  clasts  of  igneous  rock,  limestone  and  mudstone  with 
undistorted  fossils.  This  conglomerate  fines  upwards  into  siltstone  turbidites  and  mudstones, 
cleaving  subparallel  with  the  bedding,  which  yield  a rich  assemblage  of  fossils,  usually  found  in  a 
rather  distorted  state.  The  total  thickness  of  the  conglomerates  and  associated  siltstones  and 
mudstones  is  no  more  than  5 m.  These  sediments  are  interpreted  as  debris-flow  deposits,  probably 
triggered  seismically.  They  were  originally  laid  down  in  shallow  waters,  following  which,  large 
unstable  masses  of  partly  and  unlithified  sediments  slumped  rapidly  into  deep-water,  burying  their 
faunas  in  the  process.  The  sediments  at  the  two  localities  of  Kilbucho  and  the  Wandel  Burn  are  very 
similar,  though  they  lie  12  km  apart  along  the  strike.  It  is  quite  possible  that  they  record  the  events 
of  a single  debris  flow  of  vast  size  although  this  cannot  be  confirmed.  They  could,  on  the  other  hand, 
have  been  smaller,  separate,  but  near  contemporaneous  debris-flows  from  the  same  source.  All  the 
fossils  are  well-preserved  as  moulds  (Text-fig.  2a-d),  though  distorted  and  not  infrequently  cracked, 
possibly  during  transportation  or  through  diagenetic  effects.  The  fossiliferous  mudstones  and 
siltstones  are  a classic  obrution  deposit,  the  fossils  often  being  preserved  at  an  angle  to  the  bedding. 
A full  description  of  the  localities  and  other  faunas  is  in  preparation  (Clarkson,  Harper,  Owen  and 
Taylor  in  prep.).  As  well  as  a rich  variety  of  brachiopods  and  trilobites,  there  are  also  bryozoans 
(especially  common  at  Wallace's  Cast),  ostracodes,  bivalves,  gastropods,  nautiloids  and  crinoids  in 
addition  to  the  material  described  here.  Scattered  solitary  rugose  corals  are  present  at  Wallace’s 
Cast  and  rarely  in  mudstone  clasts  in  the  conglomerate  at  Kilbucho.  The  new  genus  described  here 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


181 


text-fig.  I Map  of  the  mid-north  Southern  Uplands  of  Scotland  indicating  collecting  sites  at  Kilbucho  and 
Wallace’s  Cast.  Area  of  detailed  map  located  in  inset. 


is  known  only  from  two  poor  fragments  from  Wallace’s  Cast  but  is  common  in  a wide  range  of 
ontogenetic  stages  in  a coarse-silt  grade  turbidite  at  Kilbucho,  where  it  appears  not  to  be  associated 
with  rugose  corals. 

The  graywacke  group  in  which  the  Kilbucho-Wandel  Burn  sequence  occurs  lies  within  Tract  2 of 
the  Southern  Uplands  (Leggett  et  al.  1979)  and  belongs  to  the  Kirkcolm  Formation  (J.  Floyd  pers. 
comm.).  The  trilobite  fauna  is  fairly  diverse,  there  being  twelve  species  (A.  Owen  pers.  comm.),  and 
there  are  up  to  twenty-four  species  of  brachiopods  (D.  A.  T.  Harper  pers.  comm.).  Amongst  the 
trilobites,  the  most  common  faunal  elements  are  the  mid-Caradoc  (Balclatchie  and  Ardwell) 
Calyptaulax  brongniartii  (Portlock)  (see  Clarkson  and  Tripp  1982)  and  Illaenus  convergens,  with 
subsidiary  Stenopareia,  Cybeloides,  Paraharpes  and  Remopleurides.  The  numerous  brachiopods  are 
very  similar  to  those  of  the  Bardahessiagh  Formation,  Pomeroy,  Northern  Ireland  (Mitchell  1977), 
of  high  Ardwell  age,  but  some  of  the  elements  are  also  found  in  the  Balclatchie  and  Ardwell  Beds 
at  Girvan.  The  total  age  range  of  the  Kilbucho-Wandel  faunas  cannot  for  the  moment  be  dated 
more  accurately  than  mid-Caradoc  (Soudleyan  - Actonian). 


182 


PALAEONTOLOGY,  VOLUME  34 


EXPLANATION  OF  PLATE  1 

Figs  1-8.  Kilbuchophyllia  discoidea  gen.  et  sp.  nov.;  all  scanning  electron  micrographs  of  gold  coated  latex 
replicas;  Ordovician,  nhd-Caradoc;  Kilbucho,  near  Biggar,  southern  Scotland.  1 and  2,  RMS  1989.36.4, 
mature  septal  blade,  corallum  axis  to  left;  note  pattern  of  diverging  columnar  units  in  fractured  face  in  fig. 
2;  1,  x 15;  2,  x 60.  3,  RMS  1989.36.5,  oblique  view  of  individual  trabecular  spine  set  on  internal  surface  of 
epitheca  at  peripheral  margin  of  corallum,  x 150.  4,  RMS  1989.36.2,  plan  view  of  pair  of  trabecular  spines 
in  mid  septum,  x 150.  5 and  6,  RMS  1989.36.6,  external  surface  of  epitheca,  periphery  of  corallum  bottom 
right;  5,  general  view  showing  prominent  septal  grooves  and  growth  ridges,  x 15;  6,  detail  of  growth  ridge 
crossing  interseptal  ridge,  x45.  7,  RMS  1989.36.4,  pattern  of  nested  triads  developed  about  third  order 
septum  in  centre  of  figure;  first  order  septum  to  left  of  group,  second  order  septum  to  right  of  group,  x 15. 
8,  RMS  1989.36.5,  papillose  axial  structure  of  merged  trabecular  spines,  x 30. 


text-fig.  2.  Kilbuchophyllia  discoidea  gen.  et  sp.  nov.  Ordovician,  mid-Caradoc,  Kilbucho,  near  Biggar, 
southern  Scotland,  a-d,  original  moulds;  a,  RMS  1989.36.2,  calical  surface  of  immature  specimen  in  which 
septa  are  weakly  linked  spines  (compare  with  Text-figs  3e,  f);  axis  of  symmetry  vertical,  x 5;  b,  RMS  1989.36.1 
(holotype),  calical  surface  of  mature  specimen  in  which  septa  are  solid  blades  (compare  Text-fig.  3g,  h);  axis 
of  symmetry  vertical,  x2-5;  c and  d,  RMS  1989.36.7,  calical  surface;  undersurface  of  epitheca,  part  and 
counterpart,  x 3.  E,  RMS  1989.36.8,  latex  replica  of  external  surface  of  epitheca  showing  well  developed 

interseptal  grooves  and  growth  ridges,  x 4. 


PLATE  1 


SCRUTTON  and  CLARKSON,  Kilbuchophyllia 


184 


PALAEONTOLOGY,  VOLUME  34 


PREPARATION 

The  mouldic  material,  preserved  in  a coarse-silt  grade,  quartz-rich  turbidite  with  a substantial  mica  and  clay 
mineral  matrix,  was  cleaned  in  a weak  solution  of  Calgol  in  an  ultrasonic  bath  and  latex  replicas  were  made 
using  standard  techniques.  Although  these  replicas  demonstrate  overall  three-dimensional  appearance  of  the 
coral,  distortion  of  the  septal  blades,  either  taphonomic  or  tectonic,  tends  to  obscure  the  detailed  interseptal 
relationships  in  most  specimens.  Therefore,  septal  patterns  were  traced  directly  from  the  moulds  using  a camera 
lucida  attachment  on  the  microscope.  These  reflect  the  growth  of  the  septal  blades  on  the  upper  surface  of  the 
epitheca  and  are  thus  likely  to  reflect  the  interseptal  relationships  most  accurately.  For  the  purposes  of 
illustration  in  Text-figure  3,  these  patterns  have  been  reversed  to  show  the  standard  calical  view  of  septal 
arrangement  in  corals. 

The  latex  replicas  were  used  for  SEM  study  of  septal  microarchitecture.  Selected  replicas  were  coated  with 
gold  under  vacuum  to  a thickness  of  12-15  nnr  and  examined  at  a range  of  magnifications  using  a Cambridge 
Instruments  Stereoscan  240  in  the  Biomedical  E.M.  Unit  at  the  University  of  Newcastle  upon  Tyne.  Problems 
of  creep  in  the  latex  were  solved  by  working  at  low  energy  levels,  between  0-5  and  4 kV.  Very  low  magnification 
pictures  taken  at  settings  for  maximum  depth  of  field,  such  as  that  in  Text-figure  3h,  suffer  from  slight  spherical 
distortion  but  have  been  preferred  for  their  clarity  over  light  microscope  photographs. 

In  coral  studies,  mouldic  preservation  is  usually  regarded  as  of  limited  value.  It  is  less  of  a disadvantage  in 
the  present  material  because  of  the  discoidal  growth  form  and  lack  of  horizontal  elements  between  the  septa : 
no  macrostructural  detail  is  lost.  However,  the  SEM  results  obtained  here,  suggest  that  all  mouldic  material 
may  repay  closer  examination. 

MORPHOLOGICAL  CHARACTERISTICS 

A full  description  of  this  new  species  is  given  below.  The  present  discussion  concentrates  on  the  two 
most  important  features  bearing  on  the  anthozoan  cnidarian  nature  of  the  material  and  its 
phylogenetic  relationships  within  the  class:  microarchitecture  of  the  skeletal  elements  and  septal 
pattern. 

Microarchitecture 

SEM  study  of  gold-coated  latex  replicas  reveals  the  preservation  of  elements  of  about  20  //m  and 
above  in  the  better  preserved  material.  Individual  septal  spines  of  up  to  200  /mi  diameter,  in 
specimens  RMS  1989.36.2  and  5,  are  constructed  of  upward  and  outwardly  diverging  columnar 
units  of  indeterminate  length  and  subrectangular  to  rhomboidal  to  irregular  (?oblique)  section,  c. 
20  /mi  across  (PI.  1,  figs  3 and  4).  Viewed  from  above,  terminations  give  the  appearance  of 
overlapping  roof  tiles,  possibly  helically  arranged  in  a conical  stack.  Where  spines  are  first  linked 
to  form  continuous  but  beaded  septal  plates,  the  intervening  ridges  are  composed  of  units  of  similar 
size  and  shape.  In  larger  coralla,  in  which  individual  spines  have  been  subsumed  into  dentate,  flat 
faced  septal  blades,  the  lateral  faces  of  the  blades  have  the  appearance  of  a uniform  fabric  of 
overlapping  scales  (PI.  1,  figs  1 and  2).  On  the  fractured  surface  of  a septal  tooth,  internal  upward 
fanning  of  columnar  units  is  visible;  the  effect  of  overlapping  scales  is  produced  by  oblique 
terminations  of  these  units  at  the  surface.  No  substructure  is  visible  within  these  units. 

The  axial  structure  in  some  smaller  coralla  is  composed  of  a cluster  of  discrete  spines  (PI.  1,  fig. 
8).  These  have  the  same  structure  as  the  septal  spines  and  are  clearly  septal  in  origin. 

The  basal  surface  of  the  epitheca  shows  circumferential  ridges,  demarcating  growth  increments, 
and  sometimes,  except  in  the  axial  area,  radiating  septal  grooves  (PI.  1,  fig.  5;  Text-fig.  2d,e).  In 
between  ridges,  the  surface  is  smoother  and  may  be  very  smooth  to  almost  featureless.  At  the  ridges, 
a cluster  of  overlapping  triangular  to  arcuate  elements  averaging  40  //m  across  forms  a low  scarp 
slope  directed  towards  the  axis  (PI.  1,  figs  5 and  6).  Individual  elements  are  oriented  radially  and 
offlap  towards  the  periphery,  the  ultimate  series  in  each  ridge  subparallel  to  the  inter-ridge  surface 
of  the  epitheca.  The  calicular  surface  of  the  epitheca  is  rather  smooth  and  undulating  in  places  but 
elsewhere  shows  sub-vertically  orientated  elements  with  low  pyrimidal  terminations  approximately 
20-40  //m  across.  These  define  a fabric  which  appears  to  have  a crudely  radial  orientation  in  places 
(PI.  1,  fig.  3). 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


185 


Septal  pattern 

Septa  are  arranged  radially,  reaching  up  to  0-8  of  the  corallum  radius  in  length,  on  a flat,  circular 
(see  below)  basal  disc.  Pattern  is  most  readily  detected  in  the  smaller  coralla  with  about  30-40  septa. 
In  larger,  mature  coralla,  with  up  to  120  septa,  not  only  are  most  specimens  incomplete  but  septal 
arrangement  becomes  increasingly  irregular. 

Two  features  reveal  the  septal  pattern  : the  relative  length  of  the  septa,  and  curvature  of  the  inner 
ends  of  septa  of  higher  order  to  face,  or  rest  against  the  flanks  of  septa  of  lower  order  (PI.  1,  fig. 
7).  In  RMS  1989.36.2  (Text-figs  2a  and  3e,  f),  12  septa  of  approximately  equal  length  extend  0 8 
radius  to  the  axis.  Of  these,  alternate  septa  are  each  flanked  by  two  shorter  septa,  between  0-5  and 
0-75  radius  in  length,  whose  axial  ends  turn,  more  or  less  strongly,  towards  each  other  and  the 
opposite  faces  of  the  dividing,  longer  septum.  There  are  thus  12  of  these  shorter  septa.  Eight  of  these 
are  again  each  flanked  by  a pair  of  even  shorter  septa,  01  to  0 5 radius  in  length  and  converging 
on  opposite  faces  towards  the  axis.  This  repeated  pattern  of  septal  convergence  leads  to  the 
appearance  of  nested  triads  of  septa  of  which  there  are  six,  separated  by  six  of  the  longest  septa 
which  have  no  divergent  septal  groups.  These  latter  are  interpreted  as  six  first  cycle  septa, 
alternating  with  six  second  cycle  septa  that  form  the  axis  of  each  set  of  nested  triads.  The  successive 
groups  of  diverging  septa  represent,  respectively,  12  third  cycle  septa  and  16  fourth  cycle  septa, 
amounting  to  40  septa  in  all.  The  fourth  cycle  here  is  regarded  as  incomplete,  numbering  24  septa 
when  complete.  The  two  triads  lacking  fourth  cycle  septa  are  adjacent  and  flank  an  axis  of  bilateral 
symmetry  defined  by  a short  septal  blade  in  the  axial  area  of  the  coral. 

All  of  the  available  material,  except  the  smallest  specimen,  clearly  shows  this  septal  pattern  of 
nested  triads  and  often  some  weak  indication  of  an  overall  bilateral  aspect.  Two  further  specimens 
unequivocally,  and  several  others  less  certainly,  demonstrate  the  hexameral  symmetry  of  the  pattern 
of  triads.  One,  RMS  1989.36.4  (PI.  1,  fig.  7),  is  only  slightly  larger  than  RMS  1989.36.2  and  shows 
complete  first  to  fourth  cycles  of  septa  and  an  incomplete  fifth  cycle  containing  10  septa.  The  pattern 
of  nested  triads  is  uncertain  and  probably  anomalous  in  one  sextant;  the  specimen  is  damaged  at 
this  point.  A bilateral  symmetry  is  suggested  by  the  5th  cycle  occurring  almost  exclusively  in  two 
opposite  sextants.  RMS  1989.36.1  (Text-fig.  3g,  h)  is  close  to  the  maximum  diameter  known  so  far 
for  this  coral.  It  also  shows  complete  first  to  fourth  cycles  of  septa,  whilst  the  fifth  cycle  is  better 
developed  but  still  incomplete  with  31  septa  and  the  sixth  cycle  rarely  developed  and  represented 
by  6 septa.  Bilateral  symmetry  is  again  suggested  by  septal  arrangement  in  and  around  the  axial  area 
and  by  slightly  higher  septal  numbers  in  two  opposite  sextants.  However,  the  numerical  difference 
is  small  and  peripheral  preservation  incomplete  so  that  septal  number  may  be  higher  than  apparent. 

Only  two  relatively  immature  specimens  are  available  (Text-fig.  3a-d).  No  pattern  of  convergence 
is  seen  in  the  smallest  specimen,  RMS  1989.36.3  (Text-fig.  3a,  b),  and  septal  identity  is  uncertain: 
the  interpretation  shown  draws  on  comparison  with  the  pattern  developed  in  larger  coralla.  The 
larger  specimen  shows  weakly  developed  triads.  We  have  been  conservative  in  our  interpretive 
sketch  (Text-fig.  3c)  and  faint  traces  on  the  specimen  suggest  the  possibility  of  greater  axial 
extension  of  the  third  order  septa  towards  the  second  order  septa  (Text-fig.  3d).  The  appearance  of 
third  order  septa  in  more  mature  specimens  suggests  that  some  extension  or  strengthening  of  their 
axial  ends  takes  place  as  growth  proceeds. 

The  details  of  septal  insertion  cannot  be  substantiated  by  a study  of  septal  grooves  on  the 
underside  of  the  epitheca.  These  are  only  rarely  well-developed  and  tend  to  fail  almost  completely 
in  an  axial  area  c.  4 mm  across.  Often  the  whole  epitheca  appears  to  lack  septal  grooves  (Text-fig. 
2d).  Supporting  evidence  is  limited  to  faint  indications  of  peripheral  triads,  as  at  top-right  in  Text- 
figure  2e. 

Many  specimens  show  varying  degrees  of  irregularity  in  insertion.  However,  an  overall  pattern 
emerges  of  a pair  of  adjacent  sextants  relatively  retarded  and  a further  pair  of  opposite  sextants 
relatively  accelerated.  The  pattern  is  symmetrical  about  the  plane  of  bilateral  symmetry  where  this 
is  clear  from  features  in  the  axial  area  of  the  corallum.  In  the  smallest  coralla  available  (Text-fig. 
3a-d),  retardation  is  already  apparent  in  the  adjacent  pair  of  sextants  (orientated  towards  the 


186 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  3.  For  legend  see  opposite. 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


187 


bottom  of  each  figure).  Acceleration  in  lateral  sextants  does  not  become  marked  until  the  insertion 
of  the  5th  cycle  begins.  It  may  be  so  extreme  in  some  larger  corallites  that  an  initial  impression  is 
given  of  eight  rather  than  six  sets  of  nested  triads.  An  idealized  representation  of  the  septal  pattern 
in  these  corals  is  given  in  Text-figure  4a. 


AFFINITIES  AND  RELATIONSHIPS 


Anthozoan  affinities 

The  gross  morphological  features  of  these  specimens  immediately  suggest  coralline  affinity.  The 
only  other  reasonable  possibility  seems  to  be  a relationship  to  the  Porifera,  based  on  a crude 
homeomorphy  with  forms  like  Haplistion  (Rigby  1987).  No  other  phylum  is  known  to  produce  a 
structure  of  this  size  range  and  form. 

The  microarchitecture  of  the  septa  clearly  rules  out  poriferan  affinity  and  strongly  supports 
assignment  to  the  Anthozoa  Cnidaria.  The  characteristic  pattern  of  elements  in  the  septal  spines  can 
be  matched  very  closely  among  the  Scleractinia  (for  example,  Sorauf  1972).  In  particular,  the 
appearance  of  granulations  on  the  lateral  faces  of  septa  in  Fungia , representing  one  spherulitic 
cluster  of  crystallites  (Sorauf  1972,  pi.  14,  fig.  5),  is  indistinguishable  in  appearance  from  the  tips  of 
the  septal  spines  in  the  present  material,  although  smaller  in  size  (PI.  1,  figs  3 and  4).  Granulations 
on  the  septal  faces  in  Cladocora  (Sorauf  1972,  pi.  13,  fig.  4)  are  also  similar.  The  fabric  on  the  lateral 
faces  of  septal  blades  (PI.  1,  figs  1 and  2)  compares  with  that  in  Fungia  scutarea  (Sorauf  1972,  pi. 

1 1,  fig.  2)  but  is  much  coarser.  The  elongate  units  defined  in  the  present  material  are  assumed  to  be 
composed  of  bundles  of  fine  acicular  crystals,  not  resolvable  here  either  because  of  the  limitations 
of  the  moulding  medium,  or  recrystallization,  or  both.  However,  there  seems  to  be  sufficient 
evidence  to  establish  the  septal  spines  as  trabeculate.  Such  microstructure  appears  to  be 
characteristic  of  the  anthozoan  Cnidaria. 

This  evidence,  together  with  the  discoidal  epithecate  form  and  the  radial  distribution  of  the 
spinose  or  bladelike  septa,  clearly  identifies  this  material  as  a zoantharian  coral. 

Affinities  within  the  Anthozoa 

In  detail,  this  material  is  unlike  any  other  known  Palaeozoic  coral,  either  from  the  established 
Rugosa  or  Heterocorallia,  or  the  more  scattered  and  problematic  Cambrian  material.  It  is  grossly 
most  similar  to  some  solitary,  discoidal  Rugosa  (for  example,  Hill  1981,  fig.  39)  but  is  fundamentally 
distinguished  from  them  by  its  septal  arrangement.  These  new  specimens  unequivocally  show  six- 
fold cyclic  insertion  in  contrast  to  the  serial  insertion  in  four  quadrants  of  rugose  corals..  The  septal 
development  in  Hexacorallia,  based  on  four  primary  septa  (Hill  1981),  is  even  more  distinct.  On  the 
other  hand,  this  pattern  of  cyclic  insertion  is  indistinguishable  from  that  in  scleractinian  corals 
(Vaughan  and  Wells  1943;  Wells  1956;  Jell  1980;  Oliver  1980).  The  tendency  for  cycles,  particularly 
above  the  third,  to  be  incomplete  when  higher  cycles  are  initiated  is  common  in  Scleractinia.  The 
evidence  of  bilateral  symmetry  is  also  seen  in  septal  development  in  many  scleractinians  and,  as 
pointed  out  by  Oliver  (1980),  is  a reflection  of  the  fundamental  radiobilateral  symmetry  of  all  known 
anthozoans.  A dorso-ventral  polarity  in  the  insertion  of  septal  cycles  is  a feature  of  some 
scleractinians  (Vaughan  and  Wells  1943;  Wells  1956;  Oliver  1980)  and  we  interpret  the  relative 
retardation  of  a pair  of  sextants  in  the  present  material  to  indicate  the  equivalent  of  the  ventral  pole 


text-fig.  3.  Kilbuchophyllia  discoidea  gen.  et  sp.  nov.  Ontogenetic  series,  Ordovician,  mid-Caradoc,  Kilbucho, 
near  Biggar,  southern  Scotland.  Photographs  (b  and  d)  and  scanning  electron  micrographs  (f  and  h)  of  latex 
replicas  of  calical  surfaces  are  matched  with  interpretive  sketches  based  on  information  from  original  moulds 
and  corresponding  replicas.  Plane  of  bilateral  symmetry  vertical,  supposed  dorsal  pole  at  top.  Septal  cycle 
indicated  as  follows:  protosepta,  long  heavy  lines;  2nd,  3rd  and  4th  cycles,  successively  shorter  light  lines; 
5th  cycle,  spots;  6th  cycle,  unornamented,  a and  b,  RMS  1989.36.3,  x 8.  c and  d,  BGS  9936,  x 8.  e and  f,  RMS 
1989.36.3,  x 6.  G and  h,  RMS  1989.36.1  (holotype),  x2-5. 


PALAEONTOLOGY,  VOLUME  34 


in  scleractinians.  In  conformity  with  scleractinian  usage,  we  have  orientated  the  presumed  dorsal 
pole  uppermost  in  the  material  described  here.  However,  we  are  not  aware  of  relative  acceleration 
in  the  pair  of  opposite  sextants  in  scleractinians. 


thxt-fig.  4.  a,  Kilbuchophyllia  discoidea  gen.  et  sp.  nov.  Idealized  reconstruction  of  septal  pattern.  Plane  of 
bilateral  symmetry  vertical  with  supposed  dorsal  pole  uppermost,  b,  Fungiacyathus  symmetricus  (Pourtales). 
BM(NH)Z  1880.1  1.25.123,  Recent  specimen,  collection  station  details  uncertain,  x4. 


The  distinctive  pattern  of  nested  triads  of  second  and  higher  orders  of  septa  is  similar  to  a version 
of  Portales  Plan  which  is  developed  in  some  scleractinian  corals.  Pourtales  Plan  is  regarded  as  a 
reflection  of  septal  substitution  during  ontogeny,  when  the  peripheral  ends  of  exosepta  split  to 
accommodate  subsequent  entosepta.  Vaughan  and  Wells  (1943,  p.  34)  stated  that  it  may  be  assumed 
that  substitution  has  occurred  when  septa  of  a higher  cycle  unite  with  those  of  a lower  cycle.  A range 
of  patterns  of  uniting  septal  ends  is  possible  in  detail,  but  the  arrangement  in  the  present  material 
is  remarkably  similar  to  that  exhibited  by  such  Scleractinia  as  Fungiacyathus  symmetricus  (Text-fig. 
4b;  Vaughan  and  Wells  1943,  pi.  34,  figs  la  and  4)  and  Balanophyllia  ( Eupsammia ) zelandiae  (Squires 
1958,  p.  73,  fig.  28).  However,  this  is  not  identical  to  the  classic  pattern  in  dendrophyllid  corals 
illustrated  by  Vaughan  and  Wells  (1943,  fig.  13)  and  Wells  (1956,  fig.  239)  in  which  the  entosepta 
are  less  well-developed  than  the  exosepta.  Also  the  pattern  in  the  present  material  is  equivocal.  The 
axial  septum  of  a triad  is  usually  more  or  less  structurally  continuous  and  the  flanking  septa  bend 
towards  but  do  not  always  touch  or  merge  with  the  axial  septum.  This  does  not  immediately  suggest 
the  process  of  substitution.  In  some  cases  the  peripheral  ends  of  existing  septa  are  deflected  around 
the  tips  of  newly  inserted  septa,  at  this  stage  a string  of  septal  spines,  in  a manner  suggesting 
substitution.  However,  we  cannot  be  certain  that  these  instances  are  not  irregularities  in  insertion 
rather  than  clues  to  its  character.  If  septal  splitting  did  occur,  the  appearance  of  septa  in  the  smaller 
specimens  suggests  that  it  was  unlikely  to  have  affected  either  the  first  or  second  orders.  It  seems 
also  that  further  work  is  needed  on  the  origin  of  some  of  the  patterns  attributed  to  Pourtales  Plan 
in  living  corals.  Thus  it  is  premature  to  claim  septal  substitution  as  occurring  in  this  Ordovician 
material. 

This  very  close  similarity  to  the  Scleractinia  is  reflected  in  other  features.  The  origination  of  septa 
as  discrete  spines,  subsequently  linked  by  thin  blades  of  material  to  give  a beaded  appearance  to  the 
septa,  is  very  reminiscent  of  the  early  stages  of  skeletal  development  in  some  Recent  corals  (see,  for 
example,  Jell  1980).  The  rather  confused  appearance  and  irregularities  in  metasepta  insertion  in  the 
early  ontogenetic  stages  mentioned  and  illustrated  by  Jell  are  very  similar  to  those  seen  here. 
Furthermore,  the  coarsely  denticulate  upper  margins  of  the  septal  blades  in  mature  coralla  are  also 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


189 


closely  comparable  to  those  seen  in  many  scleractinian  corals  but  are  not  a characteristic  of  the 
Rugosa.  An  epitheca  or  holotheca  is  almost  universal  among  rugose  corals  but,  as  a well  developed 
feature,  is  confined  largely  to  some  ahermatypic  (mainly  caryophyllid  and  dendrophyllid)  forms 
among  the  Scleractinia.  In  the  Rugosa  and  Tabulata,  it  appears  always  to  develop  from  an  initial 
conical  structure  secreted  by  the  polyp  on  settlement  and  metamorphosis,  whereas  in  the 
Scleractinia  it  develops  on  the  edge  of  the  basal  disc  (Jell  1980).  In  the  present  material  the  central 
area  of  the  epitheca  is  featureless  and  flat;  there  is  no  sign  of  a conical  stage  in  development  (Text- 
fig.  2d,e).  The  microarchitecture  of  the  epitheca  shows  similarities  with  that  described  for  Manicina 
by  Sorauf  (1972),  although  the  structures  preserved  here  are  much  coarser  in  scale.  Also,  the 
character  of  the  upper  surface  conforms  closely  in  appearance  to  the  secondary  layer  on  the  surface 
of  the  basal  disc  of  Porites  lutea  illustrated  by  Jell  (1980). 

These  specimens  occur  with  a rich  invertebrate  fauna,  preserved  almost  exclusively  as  moulds,  the 
vast  majority  of  which  originally  had  calcium  carbonate  shells  or  skeletons.  The  skeletal  material 
is  thus  assumed  to  have  been  calcium  carbonate.  Whether  the  skeleton  was  originally  calcitic  or 
aragonitic  is  much  more  speculative.  Little  is  known  of  microarchitecture  in  the  rugose  corals, 
widely  regarded  to  have  been  originally  calcitic  (Sandberg  1984),  although  internal  ultrastructure 
appears  to  be  identical  to  that  in  the  Scleractinia.  Sorauf  (1980,  p.  335)  considered  that 
biomineralization  in  the  Rugosa  closely  resembled  that  in  the  Scleractinia,  differing  only  in  original 
mineralogy.  In  any  case,  in  the  material  described  here  the  finest  detail  of  the  microarchitecture  is 
not  preserved.  The  only  evidence  is  indirect;  similarity  to  the  Scleractinia  is  so  close  that  the  original 
mineralogy  may  well  have  been  the  same,  that  is  to  say  aragonitic. 

Phylogenetic  relationships 

The  evidence  suggests  very  close  affinity  between  this  Ordovician  material  and  the  Scleractinia 
among  the  Zoantharia  Anthozoa.  It  seems  highly  improbable  that  intermediates  over  a period  of 
220  Ma  could  all  have  escaped  preservation  and/or  detection  even  if  it  is  assumed  that  these  corals 
remained  ecologically  confined  to  oceanic  environments.  In  fact  the  associated  organisms  clearly 
indicate  a shelf  and/or  upper  slope  fauna.  It  seems  more  probable  that  the  Palaeozoic  specimens 
represent  an  earlier,  ultimately  unsuccessful  attempt  at  skeletonization  by  the  same  group  of 
anemones  that  later  gave  rise,  probably  polyphyletically,  to  the  Scleractinia.  Such  a conclusion 
requires  the  existence  of  anemones  with  a cyclic  hexameral  pattern  of  mesenterial  insertion  at  least 
as  early  as  the  mid-Ordovician.  Thus  it  strongly  supports  the  rejection  of  the  Rugosa  as  ancestral 
to  the  Scleractinia  (Oliver  1980). 

The  ancestral  anemone  group  is  usually  considered  to  be  the  Corallimorpharia,  identical  to 
scleractinian  polyps  but  skeletonless  (Wells  and  Hill  1956;  Hill  1981;  Oliver  and  Coates  1987). 
although  Hand  (1966)  has  suggested  the  possibility  of  the  reverse  relationship  on  functional 
grounds,  with  the  Corallimorpharia  and  Actiniaria  evolved  from  the  Scleractinia  by  loss  of  the 
skeleton.  The  new  Ordovician  material,  however,  appears  to  favour  the  former  scenario. 
Furthermore,  if  its  septal  pattern  can  be  confirmed  to  be  identical  to  one  known  to  result  from  septal 
substitution  in  living  corals,  this  isolated  skeletonized  species  would  itself  presumably  require  an 
anemone  precursor  already  possessing  paired  mesenteries.  Thus  the  range  of  the  Corallimorpharia, 
and/or  the  closely  related  Actiniaria,  must  be  extended  back  at  least  that  far  to  provide  the  same 
ancestral  anemone  stock  for  this  and  the  Scleractinia.  Anemones  have  an  almost  non-existent  fossil 
record  (Scrutton  1979)  but  it  now  seems  possible  that  all  the  various  groups  of  anemones  may  have 
differentiated  during  the  initial  cnidarian  radiation  in  the  late  Precambrian. 

A possible  phylogeny  for  the  Palaeozoic  Zoantharia  Anthozoa,  modified  after  that  of  Oliver  and 
Coates  (1987),  is  given  in  Text-figure  5.  The  present  material  has  the  same  relationship  to  the 
Scleractinia  as  the  Middle  Cambrian  Cothoniida  probably,  but  perhaps  less  certainly,  has  to  the 
Rugosa  (Jell  and  Jell  1976;  Scrutton  1979;  Oliver  and  Coates  1987).  The  latter  are  regarded  as 
having  evolved  from  the  Zoanthiniaria,  in  which  later  mesenterial  couples  are  inserted  serially  in 
only  one  pair  of  sextants  (Wells  and  Hill  1956;  Hill  1981).  The  relationships  of  the  other  major 
group  of  Palaeozoic  corals,  the  Tabulata  (taken  to  include  the  Heliolitida)  is  equivocal.  Some  or  all 


190 


PALAEONTOLOGY,  VOLUME  34 


Free. 

Palaeozoic 

post-Palaeozoic 

V 

€ 

0 

S 

D 

C 

p 

post  T 

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/ 

I 

1 

9 

1 

Cothon 

r 

1 

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R 

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ugosa 

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Scleractinia 

— ► 

text-fig.  5.  Phylogeny  of  the  Anthozoa  Zoantharia  (modified  after  Oliver  and  Coates  1987). 


Rugosa  have  been  claimed  to  have  direct  tabulate  ancestry  (Flower  1961)  but,  although  the  earliest 
skeletal  ontogenetic  stage  appears  always  to  be  conical  as  in  the  Rugosa,  we  regard  this  as  most 
unlikely  (Scrutton  1979;  Neuman  1984).  Septa  are  absent  or  weakly  developed  in  the  Tabulata  and 
no  general  pattern  of  insertion  has  been  demonstrated.  Tabulate  corallites  rather  seldom  show 
bilateral  symmetry;  septal  development  is  usually  radially  uniform  and  12  septa  are  sufficiently 
common,  together  with  a rare  instance  of  preservation  of  twelve  tentacled  favositid  polyps,  for  a 
fundamental  dodecal  symmetry  to  have  been  claimed  for  the  group  (Copper  1985;  Mistiaen  1989). 
These  factors  suggest  a corallimorpharian  or  actiniarian  ancestor  to  be  as,  if  not  more,  likely  for  this 
group  than  a zoanthiniarian  ancestor  among  known  orders  of  anemones,  although  it  seems  equally 
possible  that  the  tabulates  evolved  from  a separate  group  of  anemones  now  extinct. 


SYSTEMATIC  PALAEONTOLOGY 


Phylum  cnidaria  Hatschek,  1888 
Class  anthozoa  Ehrenberg,  1834 
Subclass  zoantharia  de  Blainville,  1830 
Order  kilbuchophyllida  nov. 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


191 


Diagnosis.  As  for  genus. 

Discussion.  The  Kilbuchophyllida  is  homoeomorphic  to  a high  degree  with  the  Scleractinia. 
However,  the  combination  of  a solitary  discoidal,  epithecate  form  lacking  dissepiments,  with  solid, 
bladed  septa  nested  in  triads  and  more  or  less  strongly  accelerated  in  the  lateral  sextants,  does  not 
appear  to  occur  among  the  Mesozoic  to  Cenozoic  scleractinian  corals.  Although  the  combination 
of  characters  in  the  only  known  species  is  unique,  all,  with  the  possible  exception  of  the  pattern  of 
septal  acceleration,  are  individually  or  severally  found  in  various  scleractinians.  Ultimately,  the 
classification  of  this  species  in  a new  order  is  based  on  its  stratigraphic  separation  and  our 
presumption  of  lack  of  direct  descent  to  the  Scleractinia. 

Family  kilbuchophyllidae  nov. 

Diagnosis.  As  for  genus. 

Genus  kilbuchophyllia  gen.  nov. 

Derivation  of  name.  After  the  type  locality,  Kilbucho  (pron.  -bukko),  near  Biggar,  southern  Scotland. 

Diagnosis.  Solitary,  discoidal,  epithecate  radiobilateral  corals  showing  hexameral,  cyclic  septal 
insertion.  Septa,  spinose  to  solid  blades,  arranged  in  a pattern  with  the  internal  ends  of  higher  order 
septa  turned  towards  or  resting  against  the  flanks  of  lower  order  septa.  Adjacent  sextants  (?ventral 
pole)  with  retarded  septal  insertion  in  early  ontogeny,  lateral  sextants  accelerated  in  later  ontogeny. 
No  dissepiments. 

Kilbuchophyllia  discoidea  sp.  nov. 

Plate  1,  figs  1-8;  Text-figs  2,  3,  4a,  6 

Diagnosis.  Circular,  solitary,  discoidal  corals  with  diameter  up  to  28  mm  and  estimated  maximum 
120  septa.  Up  to  six  cycles  of  septa  of  which  the  fourth  sometimes  and  the  fifth  and  sixth  cycles 
always  are  incomplete.  Second  and  higher  orders  involved  in  pattern  of  nested  triads.  Insertion 
retarded  in  adjacent  (?ventral)  sextants  in  early  ontogeny,  accelerated  in  lateral  sextants  in  later 
ontogeny.  Axial  area  with  discrete  trabeculae  (?pali)  merging  to  form  papillose  or  contorted  axial 
structure.  Weak  bilateral  symmetry  usually  apparent.  Epitheca  a flat  disc  with  concentric  growth 
ridges  and  occasionally  septal  grooves.  No  dissepiments. 

Holotype.  RMS  1989.36.1.  Ordovician,  middle  Caradoc;  Kilbucho,  near  Biggar,  southern  Scotland. 
Paratvpes.  RMS  1989.36.2-12;  BGS  9936.  Same  horizon  and  locality  as  holotype. 

Description.  Solitary,  circular,  discoidal  corals  ranging  from  2-6  mm  diameter  with  15  septa  to  27-5  mm  with 
estimated  120  septa  (Text-fig.  6).  In  small  coralla,  septa  either  discrete  trabecular  spines  or  in  lower  order  septa, 
spines  linked  by  a low  thin  ridge  giving  septa  a beaded  appearance.  In  larger  coralla,  spines  subsumed  in 
smooth  faced  blades,  c.  0-3  mm  thick,  with  coarsely  toothed  upper  margin  in  all  but  highest  order  septa, 
although  less  completely  fused  peripherally  and  particularly  adaxially.  Individual  spines  c.  0-2  mm  diameter 
with  axes  c.  0-3  mm  apart;  septa!  teech  spaced  c.  0- 7-0-9  mm.  Height  of  spines  or  septal  blades  0-75—1  -0  mm 
in  smaller  coralla,  rising  to  c.  2-3  mm  high  in  the  largest  coralla.  Septal  height  greatest  at  mid  length  of  smaller 
coralla,  migrating  to  axial  end  of  septa  in  larger  coralla.  Six  first  (protosepta)  and  six  second  cycle  septa  of  more 
or  less  equal  length,  0-8  radius  in  all  but  smallest  coralla.  Higher  cycles,  up  to  sixth,  successively  shorter  in 
length.  Second  and  higher  cycles  of  septa  involved  in  a pattern  of  nested  triads,  with  higher  cycles  at  their  inner 
ends  turned  towards  or  resting  against  the  flanks  of  lower  cycles.  The  first  two  cycles  complete  in  smallest 
available  corallum,  third  cycle  complete  between  34  mm  diameter,  fourth  cycle  complete  by  about  10  mm, 
fifth  cycle  absent  from  smaller  coralla,  ?complete  in  largest  coralla,  sixth  cycle  variably  present  only  in  largest 
coralla  and  never  complete.  Septal  insertion  retarded  in  adjacent  sextants  (at  ?ventral  pole  of  polyp)  in  early 
ontogeny,  accelerated  in  lateral  sextants  about  plane  of  bilateral  symmetry  in  later  ontogeny.  Axial  area  with 


192 


PALAEONTOLOGY,  VOLUME  34 


discrete  trabecular  spines,  ?equivalent  to  pali,  in  smallest  coralla.  With  size  increase,  spine  bases  variably 
embedded  to  form  flat  or  slightly  arched  papillose  area.  In  one  case,  spines  linked  as  extensions  of  septa  to  form 
dome  of  twisted,  interlocked  plates.  Bilateral  symmetry  may  be  weakly  defined  by  a more  or  less  well-developed 
bladed  element  in  axis  but  sometimes  not  obvious.  Epitheca  a flat  disc  with  peripheral  depth  0-3-0- 5 mm  high. 
Central  area  featureless  and  may  be  almost  smooth  throughout  but  concentric  growth  ridges  usually  and 
radiating  septal  grooves  sometimes  clearly  developed  around  central  area.  There  are  no  dissepiments. 

Discussion.  Except  for  the  smallest  specimens,  all  the  material  is  elliptical  in  plan.  When  apparent, 
the  plane  of  bilateral  symmetry  is  not  coincident  with  the  long  axis  of  the  ellipse  and  the  shape  is 
due  to  tectonic  distortion  in  the  rock.  Strain  analysis  yields  a value  of  Ri  of  T06.  Allowing  for  the 
difficulty  of  measuring  axes  accurately  in  some  of  the  material,  this  suggests  that  the  coral  was 
originally  effectively  circular. 


100  - 


* 


no.  of 
septa 


so  - 


t 


0 


0 


10 


-J 

20 


Diameter  (mm) 


30 


text-fig.  6.  Kilbuchophyllia  discoidea  gen.  et  sp.  nov.  Plot  of  septal  number  against  diameter  for  better 
preserved  material.  Both  parameters  estimated  in  many  cases  because  of  damage  to  margins  of  specimens. 

Holotype  indicated  by  asterisk. 


Variation  in  most  features  in  the  material  available,  allowing  for  ontogenetic  stage,  is  relatively 
limited.  The  axial  structure  is  the  most  variable  aspect  of  mature  specimens.  One  coral,  BGS  9936, 
representing  an  early  ontogenetic  stage,  is  unique  in  possessing  a distinct  low  rim  linking  the 
peripheral  ends  of  septa.  Whether  or  not  this  is  aberrant,  or  the  rim  is  obscured  by  thickening  of 
the  upper  surface  of  the  epitheca  in  larger  coralla,  is  unknown. 

The  specimens  often  appear  to  have  suffered  some  damage  before  final  burial,  consistent  with 
their  presence  in  a debris  flow.  In  particular,  the  septal  blades  in  the  larger  specimens  are  often 
damaged  and  their  upper  margins  incomplete.  Because  of  incomplete  preservation  there  is  an 


SCRUTTON  AND  CLARKSON:  ORDOVICIAN  CORAL 


193 


element  of  estimate  in  all  the  data  on  Text-figure  6,  although  the  error  is  considered  unlikely  to 
exceed  10%. 

Range.  This  species  is  known  so  far  from  some  20  specimens  and  fragments  from  the  type  locality.  Two 
fragments  have  been  recovered  from  similar  beds  of  the  same  age  at  Wallace's  Cast,  Wandel  Burn,  12  km  west- 
south-west  along  strike,  southern  Scotland. 

Acknowledgements . We  are  grateful  to  all  those  with  whom  we  have  discussed  various  aspects  of  this  study, 
particularly  Stephen  Cairns  (Smithsonian  Institution,  Washington,  D.C.),  Bill  Oliver  (US  Geological  Survey, 
Washington,  D.C.),  Makoto  Kato  (Hokkaido  University,  Sapporo),  Keith  Rigby  (Brigham  Young  University, 
Utah),  Martin  Le  Tissier  and  Graham  Young  (University  of  Newcastle  upon  Tyne).  Susan  Bruce  (University 
College,  Galway)  kindly  contributed  the  smallest  specimen,  which  she  collected.  Brian  Turner  commented  on 
the  matrix  to  the  specimens,  scanning  electron  micrographs  were  taken  by  Trevor  Booth  and  Text-figures  1, 
3,  5,  6 were  drafted  by  Christine  Jeans;  Peter  Lewis  and  Brian  Tuffs  helped  with  preparation  (all  University 
of  Newcastle  upon  Tyne).  Simon  Moore  (Natural  History  Museum,  London)  and  Peter  Brand  (British 
Geological  Survey,  Edinburgh)  kindly  arranged  the  loan  of  material  in  their  care. 


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COLIN  T.  SCRUTTON 
Department  of  Geology 
The  University 

Newcastle  upon  Tyne  NE1  7RU,  UK 
Present  address: 

Department  of  Geological  Sciences 
University  of  Durham 
South  Road,  Durham  DH1  3LE,  UK 

EUAN  N.  K.  CLARKSON 

Typescript  received  8 November  1989 
Revised  typescript  received  7 March  1990 


Grant  Institute  of  Geology 
West  Mains  Road 
Edinburgh  EH9  3JW,  UK 


THE  TAXONOMY  AND  SHELL  CHARACTERISTICS 
OF  A NEW  ELK  AN  1 1 D BRACHIOPOD  FROM  THE 
ASHGILL  OF  SWEDEN 

by  LARS  E.  HOLMER 


Abstract.  A new  elkaniid  brachiopod  genus  and  species,  Tilasia  rugosa , is  described  from  the  Ashgill  (Harju 
Series)  Boda  Limestone  in  the  Siljan  district  (province  of  Dalarna),  Sweden.  It  is  the  first  record  of  the 
lingulacean  family  Elkaniidae  from  the  Upper  Ordovician.  The  material  of  T.  rugosa , which  is  one  of  the  largest 
described  member  of  the  family,  is  well  preserved  and  allows  an  account  of  the  micro-ornamentation  and  shell 
structure.  The  strongly  rugose  exterior  has  a divaricate  ornamentation  with  minute  rhomboid  pits,  previously 
not  known  among  the  elkaniids. 

Elkaniid  brachiopods  are  common  and  widely  distributed  mainly  in  the  Upper  Cambrian  and 
Lower  Ordovician  (Tremadoc-lower  Llanvirn);  the  family  has  not  previously  been  recorded  from 
beds  younger  than  the  Middle  Ordovician. 

Here  a new  genus  and  species,  Tilasia  rugosa  from  the  Upper  Ordovician  (Ashgill)  Boda 
Limestone  in  the  Siljan  district,  province  of  Dalarna,  Sweden  (Text-fig.  1),  is  described.  The  rare  but 
well  preserved  material  of  this  large  elkaniid  also  permits  an  account  of  the  shell  structure  and  micro- 
ornamentation, not  previously  known  from  this  group. 


MATERIALS  AND  METHODS 

In  the  Siljan  district.  Lower  Palaeozoic  (Upper  Cambrian?  to  Silurian)  rocks  crop  out  within  a 
tectonically  complex  ring-structure,  which  probably  represents  a hypervelocity  impact  crater  (Text- 
fig.  1;  see  Jaanusson  1982  for  a review).  The  Boda  Limestone  (within  the  Amorphognathus 
ordovicicus  Biozone:  Bergstrom  1971)  is  a large  (maximum  diameter,  1000m;  thickness,  140m), 
lens-shaped,  stromatactis-bearing  unit,  with  a high  carbonate  content.  Although  reef-like,  it  lacks 
an  organic  frame;  it  represents  a carbonate  mound,  possibly  comparable  with  modern  lithoherms 
(Jaanusson  1979,  1982). 

The  phosphatic  inarticulates  (discinaceans)  from  these  beds  have  previously  been  described  by 
Lindstrom  (in  Angelin  and  Lindstrom  1880)  and  Holmer  (1987).  The  stratigraphy  and  fauna  of  the 
Boda  Limestone  were  summarized  by  Jaanusson  (1958,  1982). 

The  material  was  prepared  from  the  limestone  by  etching  with  10%  buffered  acetic  acid  (see 
Jeppsson  et  al.  1985  for  details);  the  outer  or  inner  surfaces  of  the  valves  were  covered  with  a layer 
of  epoxy  resin  to  avoid  fragmentation  during  the  etching  process.  To  study  shell  structure, 
specimens  embedded  in  epoxy  resin  were  sectioned,  polished  and  subsequently  etched  with  4% 
hydrochloric  acid  for  4 seconds;  the  counterparts  of  the  sectioned  valves  were  used  to  make  thin 
sections  for  examination  in  transmitted  light. 

The  type  material  is  housed  in  the  Department  of  Palaeozoology,  Swedish  Museum  of  Natural 
History  (SMNH),  and  in  the  Department  of  Geology,  University  of  Lund  (LO).  Detailed 
descriptions  of  the  localities  (Ostbjorka,  Boda,  Jutjarn,  and  Skalberget;  Text-fig.  1)  in  the  Siljan 
district  are  given  by  Thorslund  (1936;  see  also  Jaanusson  1982). 


(Palaeontology,  Vol.  34,  Part  1,  1991,  pp.  195— 204.| 


© The  Palaeontological  Association 


196 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  1.  Location  map  of  the  Siljan  district,  province  of  Dalarna,  Sweden,  showing  the  ring-structure  with 
Lower  Palaeozoic  rocks  (shaded)  and  the  localities  investigated  (filled  circles).  1,  Jutjarn;  2,  Ostbjorka; 

3,  Skalberget. 


SYSTEMATIC  PALAEONTOLOGY 

Class  lingulata  Goryansky  and  Popov,  1985 
Order  lingulida  Waagen,  1885 
Superfamily  lingulacea  Menke,  1828 
Family  elkaniidae  Walcott  and  Schuchert,  1908 

Diagnosis.  See  Rowefl  (1965,  p.  H270). 

Genera  assigned.  Monobolina  Salter,  1866;  Elkania  Ford,  1886;  Broeggeria  Walcott,  1902;  Lamanskya  Moberg 
and  Segerberg,  1906  [=  IDictyobolus  Williams  and  Curry.  1985];  Elkanisca  Havhcek,  1982;  Tilasia  gen.  nov. 

Discussion.  The  detailed  morphology  of  many  of  the  elkaniid  genera  listed  above  remains  poorly 
known,  perhaps  partly  because  they  have  usually  been  described  from  material  from  argillaceous 
sequences  (e.g.  Broeggeria,  Monobolina , Elkanisca)',  well  preserved  complete  specimens  from 
carbonates  have  generally  not  been  available. 

The  elkaniid  affinity  of  Monobolina  was  recently  questioned  by  Havlicek  (1982,  p.  50).  However, 
the  new  data  on  the  morphology  of  M.  plumbea  (Salter)  presented  by  Lockley  and  Williams  (1981, 
p.  15,  figs  31-34)  indicates  that  it  belongs  within  the  Elkaniidae.  Lockley  and  Williams  (1981)  also 


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197 


described  the  new  species  M.  crassa,  which  extended  the  range  of  the  family  into  the  Middle 
Ordovician  (Llandeilo). 

The  poorly  known  Lower  Ordovician  (Tremadoc)  Lamanskya  Moberg  and  Segerberg,  1906,  from 
Oland,  Sweden,  was  previously  placed  questionably  among  the  Strophomenidina  (Williams  1965, 
p.  H863),  but  is  now  considered  to  be  an  elkaniid  (Holmer  1989);  the  type  (and  only)  species,  L. 
splendens  Moberg  and  Segerberg,  is  widely  distributed  in  the  Lower  Ordovician  of  Sweden,  and  is 
currently  being  redescribed.  The  Irish  Lower  Ordovician  genus  Dictyobolus  Williams  and  Curry, 
1985  (type  species  D.  transversus  Williams  and  Curry),  which  is  here  referred  to  the  elkaniids, 
appears  to  be  a junior  synonym  of  Lamanskya  (Holmer  unpublished).  The  likewise  poorly  known 
Aulonotreta  kuraganica  Andreeva,  1972  from  the  Lower  Ordovician  of  the  Ural  Mountains 
probably  also  represents  a new  genus  of  the  elkaniid  brachiopods  (L.  E.  Popov,  personal 
communication  1989). 


Genus  tilasia  gen.  nov. 


Type  species.  Tilasia  rugosa  sp.  nov. 

Etymology.  In  honour  of  Daniel  Tilas  (1712-1772),  who  published  the  first  detailed  account  of  the  Lower 
Palaeozoic  strata  of  Dalarna  (Tilas  1740). 

Diagnosis.  Large,  transversely  suboval,  moderately  and  subequally  biconvex,  rugose  shell;  exterior 
pitted  with  rhomboid  pits.  Ventral  pseudointerarea  with  wide  propareas  and  deep,  triangular 
pedicle  groove;  ventral  umbonal  muscle  scar  divided  by  anteriorly  directed  extension  of  the  pedicle 
groove.  Dorsal  pseudointerarea  with  wide  median  groove  and  narrow  propareas. 

Species  assigned.  Tilasia  rugosa  sp.  nov.;?  Obolus ? sp.  3 Cooper,  1956. 


Tilasia  rugosa  sp.  nov. 

Text-figs  2-5 

Holotype.  SMNH  Bi  1 33686,  almost  complete  shell  (width  26-6  mm,  length  22-4  mm,  thickness  10  0 mm) 
from  the  Boda  Limestone,  Jutjarn  quarry,  Siljan  district,  Dalarna  (coll.  M.  Frye). 

Paratypes.  All  material  from  the  Boda  Limestone,  Siljan  district,  Dalarna;  SMNH  Br  133691,  incomplete 
dorsal  valve,  Skalberget  quarry  (coll.  E.  Jarvik;  flank  facies;  locality  8 in  Jaanusson  1982,  fig.  3;  SMNH 
Brl02556o,  incomplete  dorsal  valve  (previously  identified  as  fragmentary  dorsal  valve  of  Orbiculoidea ? gibba 
in  Holmer  1987,  p.  320),  Skalberget  quarry  (flank  facies;  coll.  J.  Martna);  LO  5956,  incomplete  ventral  valve, 
Ostbjorka  (coll.  S.  L.  Tornquist);  LO  5957  (not  figured),  incomplete  ventral  valve,  Boda  (coll.  S.  L.  Tornquist). 
Total  of  two  dorsal  and  two  ventral  valves. 

Etymology.  Latin  rugosus , wrinkled;  alluding  to  the  rugose  ornamentation. 

Diagnosis.  As  for  genus. 


Description.  Shell  large  (up  to  26  6 mm  wide  and  22-4  mm  long  in  one  specimen),  and  moderately,  subequally 
biconvex,  38%  as  thick  as  wide  (Text-figs  2a  and  3e);  transversely  suboval  in  outline.  Ornamentation  strongly 
rugose  (see  also  below)  with  regularly  disposed,  up  to  0-5  mm  high  rugae,  on  average  05  mm  apart  (Text-figs 
3a,  d,  f,  i and  4a-f). 

Ventral  valve  (of  holotype)  1 mm  longer  than  dorsal  valve,  84%  as  long  as  wide,  but  less  convex  (about 
I mm  difference),  15%  as  high  as  wide  (Text-figs  2a  and  3a,  e).  Interior  of  ventral  valve  not  known  in  detail; 
ventral  pseudointerarea  14-16  mm  wide  (in  two  specimens),  occupying  50%  of  valve  width,  with  well 
developed  propareas,  F3  mm  wide;  deep,  triangular  pedicle  groove,  4-3  mm  wide  and  1-6  mm  long;  ventral 
umbonal  muscle  scar  divided  by  anteriorly  directed  extension  of  pedicle  groove  (Text-figs  2b  and  4g— i).  An 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  2.  Tilasia  rugosa  sp.  nov.  a,  lateral  profile  of  complete  shell,  based  on  SMNH  Br  133686.  b,  ventral 
interior,  based  on  LO  5956.  c,  dorsal  interior,  based  on  SMNH  Brl 33686.  All  x 6.  U,  umbonal  muscle  scar; 
VL,  vascula  lateralia\  C,  central  muscle  scar;  PL,  platform;  A,  anterior  lateral  muscle  scar;  VM,  vascula  media. 


unfigured,  poorly  preserved  fragment  of  a ventral  valve  (No.  LO  5957)  shows  a section  through  an  elevated 
platform,  directly  anterior  to  the  umbonal  muscle  scars,  but  the  detailed  morphology  of  the  platform  is  not 
known. 

Dorsal  valve  (of  holotype)  80%  as  long  as  wide,  and  23%  as  high  as  wide  (Text-figs  2a  and  3b,  e).  Dorsal 
pseudointerarea  with  median  groove,  5 6 mm  wide  and  0 6 mm  long;  exact  dimensions  of  propareas  unknown, 
but  they  appear  to  be  narrower  than  the  ventral  ones  (Text-figs  2c  and  3g-h).  Dorsal  umbonal  muscle  scar 
situated  directly  anterior  to  median  groove;  central  and  anterior  lateral  muscle  scars  situated  on  an  elevated, 
subtriangular  platform,  7 mm  wide  and  9 mm  long,  with  low  median  septum;  well-developed  vascular 
markings  with  vascula  lateralia  diverging  anterolaterally  from  umbonal  muscle  scar,  and  vascula  media 
diverging  anterior  to  anterior  lateral  muscle  scars  (Text-figs  2c  and  3g-h). 

Remarks  on  ontogeny.  All  the  examined  specimens  represent  adults.  The  early  ontogeny  of  T.  rugosa 
is  not  known;  the  apical  region  of  the  valves  is  fragmentary.  The  regularly  shaped,  biconvex  shells 
do  not  show  any  major  interruptions  or  changes  in  the  growth  pattern  during  the  juvenile  and  adult 
stages;  the  major  concentric  rugae  are  formed  at  regular  intervals.  In  an  early  part  of  the  juvenile 
stage  (when  the  shell  is  up  to  3 mm  wide  and  2 mm  long)  the  rugae  are  densely  spaced,  about 
016  mm  apart;  during  later  growth  stages  they  become  gradually  more  widely  spaced,  up  to  0-8  mm 
apart;  a fully  grown  shell  appears  to  have  up  to  about  fifty  major  rugae  (Text-fig.  3a,  d,  f).  In  some 
specimens  there  are  minor,  more  irregular  rugae  between  the  major  ones  (Text-fig.  4a-c). 

Discussion.  Tilasia  rugosa  differs  from  mot  other  elkaniids  (such  as  species  of  Broeggeria,  Elkanisca , 
and  Monobolina)  mainly  in  being  more  biconvex  and  strongly  rugose.  It  is  most  similar  to  species 
of  Elkania.  However,  T.  rugosa  differs  in  being  less  biconvex  and  more  rugose;  the  thickness  of  the 
type  species  E.  desiderata  (Billings)  (Rowell  1965,  p.  H270,  fig.  164:  1 a-c)  is  about  two-thirds  of  its 
width  and  most  species  of  Elkania , like  E.  hamburgensis  (Walcott),  are  smooth,  having  only  weakly 
developed  growth  lines  (Rowell  1965,  fig.  164:  1 d-f). 

Lamanskya  splendens  Moberg  and  Segerberg,  1906  (p.  71,  pi.  3:17)  and  ‘ Aulonotreta'  kuraganica 
Andreeva,  1972  (p.  46,  pi.  7:  1-3)  differ  in  being  more  strongly  biconvex;  the  thickness  of  the  latter 
is  up  to  three-quarters  of  its  width;  moreover,  the  dorsal  platforms  of  these  two  species  are  much 
higher  (Holmer  unpublished;  Andreeva  1972,  pi.  7:  3). 


HOLMER:  SWEDISH  ELKANIID  BRACHIOPOD 


199 


text-fig.  3.  Tilasia  rugosa  sp.  nov.,  Boda  Limestone  (Ashgill),  Siljan  district,  Dalarna.  a-h,  holotype,  complete 
shell,  Jutjarn,  SMNH  Brl33686;  A,  ventral  exterior,  x2;  b,  internal  mould  of  dorsal  valve,  x2;  c,  posterior 
profile,  x2;  d,  oblique  posterior  view  of  ventral  valve,  x2-5;  E,  lateral  profile,  x2;  f,  oblique  lateral  view  of 
ventral  valve,  x 2-5;  G,  detail  of  B,  x 2-8;  H,  detail  of  latex  cast  of  B,  x 3-4.  i,  exterior  of  incomplete  dorsal 

valve,  Skalberget,  SMNH  Brl02556a,  x2-5. 


T.  rugosa  is  comparatively  large  for  the  family,  the  maximum  width  being  almost  27  mm.  Most 
other  elkaniids  (such  as  Broeggeria , Elkania , and  Elkanisca)  are  generally  up  to  10  mm  wide;  only 
Monobolina  crassa  (maximum  width  23  mm)  and  ' Aulonotreta'  kuraganica  (maximum  width 
25  mm)  are  more  than  20  mm  wide.  Cooper  (1956,  p.  193,  pi.  9f:  16,  11a:  1)  described  a large, 
unnamed  obolid,  Obolusl  sp.  3,  from  the  Middle  Ordovician  Pratt  Ferry  beds  of  Alabama,  USA. 
The  interior  of  this  species  is  unknown,  but  the  strongly  rugose  exterior,  and  the  general  shape  of 
the  shell  indicate  that  it  might  possibly  be  related  to  Tilasia. 

As  noted  above,  T.  rugosa  is  the  youngest  described  elkaniid  and  the  first  record  of  the  family 
from  the  Upper  Ordovician  (Harju  Series). 

Remarks  on  autecology.  The  type  of  environment  in  which  T.  rugosa  lived  is  uncertain.  The  holotype 
is  a complete,  articulated  shell,  which  has  probably  not  been  transported  for  any  great  distance  after 
death,  but  its  exact  location  within  the  carbonate  mound  is  not  known.  The  mound  core  of  the  Boda 
Limestone  is  generally  poor  in  sedentary  macro-organisms,  and  has  dominantly  a vagile  fauna  of 
trilobites,  gastropods,  cephalopods,  and  pelecypods  (Jaanusson  1982,  p.  28).  Two  dorsal  valves, 
which  were  collected  from  the  flank  facies  of  the  mound,  are  fragmentary  and  may  have  been 
transported. 

Although  many  fossil  lingulaceans  appear  to  have  been  infaunal  burrowers  comparable  with  their 
Recent  representatives,  this  is  an  unlikely  mode  of  life  for  T.  rugosa.  The  following  characters  makes 
it  comparatively  poorly  adapted  for  burrowing  (see  Bassett  1984  and  Savazzi  1986  for  a detailed 


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PALAEONTOLOGY,  VOLUME  34 


discussion  of  this  life  strategy):  (1)  The  moderately  biconvex  shell  is  transversely  suboval  and  wider 
than  long  (rather  than  elongate  and  ‘streamlined’  as  in  Lingula).  (2)  The  visceral  area  and  the  sites 
of  muscular  attachments  are  more  posteriorly  placed  as  compared  with  other  lingulaceans  (the 
dorsal  anterior  lateral  muscle  scars  are  placed  at  about  40%  the  valve  length  from  the  posterior 
margin  in  T.  rugosa,  whereas  in  Lingula , for  example,  the  ratio  is  about  60-70%).  (3)  The 
ornamentation  is  strongly  rugose  (rather  than  smooth,  or  with  burrowing  sculptures).  Thus,  T. 
rugosa  was  probably  better  adapted  to  some  kind  of  epifaunal  mode  of  life.  The  pedicle  foramen 
appears  to  have  remained  open  throughout  ontogeny. 

Occurrence.  T.  rugosa  is  restricted  to  the  Ashgill  Boda  Limestone  of  Dalarna. 

MICRO-ORNAMENTATION 

Under  the  SEM,  the  etched  rugose  exterior  of  two  dorsal  valves  revealed  a regular  pattern  of  pits 
covering  the  post-larval  surface  (Text-fig.  4a-f).  The  apical  region  of  the  valves  is  fragmentary,  and 
the  ornamentation  is  not  known  from  this  part  of  the  shell. 

The  pits  are  evenly  distributed  and  closely  packed,  less  than  10  /mi  deep,  subequal  in  size  and 
shape,  elongate  rhomboid,  up  to  100  /mi  long  and  30  jum  wide,  with  the  largest  dimension  arranged 


text-fig.  4.  Tilasia  rugosa  sp.  nov.,  Boda  Limestone  (Ashgill),  Siljan  district,  Dalarna.  a,  exterior  of  incomplete 
dorsal  valve,  the  location  of  B indicated,  Skalberget,  SMNH  Brl  33691,  x 5.  b,  c,  d,  details  of  a,  x 19,  x 60, 
x 150,  respectively,  e,  exterior  of  partly  exfoliated,  incomplete  dorsal  valve  (see  also  Text-fig.  3i),  Skalberget, 
SMNH  Brl02556a,  x 5.  f,  detail  of  E,  x 196.  G,  interior  of  incomplete  ventral  valve,  Ostbjorka,  LO  5956,  x 10. 
h,  detail  of  G,  x 20.  i,  oblique  lateral  view  of  G,  x 15. 


HOLMER:  SWEDISH  ELK  AN  1 1 D BRACHIOPOD 


201 


perpendicular  to  the  direction  of  growth  (Text-fig.  4c).  The  geometry  of  the  ornamentation  could 
not  be  investigated  in  detail,  owing  to  the  considerable  degree  of  fragmentation  and  exfoliation  in 
the  two  available  valves.  However,  the  pits  appear  to  be  arranged  in  offset  radiating  rows  (sensu 
Wright  1981,  p.  446).  Each  rhomboid  pit  is  defined  by  two  pairs  of  parallel  ridges  (each  up  to  5 pm 
wide),  which  are  disposed  obliquely  across  the  valve  surface  and  intersect  at  about  30-40°.  This  type 
of  sculpture  is  very  suggestive  of  the  so-called  divaricate  pattern  of  ornamentation,  which  is 
responsible  for  a wide  range  of  sculptures  (including  burrowing  terraces)  in  molluscs  and 
arthropods,  but  it  has  also  been  reported  from  some  lingulacean  brachiopods  (see  Seilacher  1972 
and  Savazzi  1986  for  reviews). 

A divaricate  ornamentation  of  pits  has  not  previously  been  reported  from  the  elkaniids,  but  the 
Lower  Ordovician  species  Dictyobolus  [=  ILamanskya]  transversus  Williams  and  Curry  (1985,  p. 
189,  figs  2-7)  and  Lamanskya  splendens  Moberg  and  Segerberg  have  an  essentially  identical  type  of 
ornamentation;  a similar  type  of  sculpture  also  appears  to  be  developed  in  ‘ Aulonotreta'  kuraganica 
Andreeva.  As  noted  above,  these  taxa  are  here  considered  to  belong  within  the  family  (Holmer, 
unpublished). 

Ornamentation  comparable  to  that  of  the  elkaniids  is  also  known  from  three  other  brachiopod 
groups:  (1)  The  problematic  articulate  brachiopod  Dictyonella  has  rhomboid  pits,  very  similar  to 
those  of  Tilasia  and  arranged  in  a strict  divaricate  geometry  (see  Wright  1981  for  a detailed 
discussion);  however,  this  brachiopod  is  not  otherwise  comparable  with  the  elkaniids.  (2) 
Rhomboid,  post-larval  pits,  only  some  6 pm  across,  and  arranged  in  divaricate  rows  have  been 
described  by  Popov  et  al.  (1982,  fig.  1:  2)  and  Holmer  (1986,  fig.  40)  from  the  thin-shelled 
Ordovician  lingulacean  Paterula.  In  the  paterulids,  the  larval  shell  is  also  pitted,  with  minute, 
circular,  cross-cutting  pits,  about  2-4  pm  across,  which  are  closely  comparable  with  the  larval  pits 
of  most  acrotretaceans  (see  Biernat  and  Williams  1970).  Popov  et  al.  (1982,  p.  103)  suggested  that 
both  the  larval  and  post-larval  pits  of  Paterula  represent  moulds  of  a vesicular  periostracum,  as  in 
the  ‘bubble  raft’  model  originally  proposed  for  the  acrotretacean  larval  shell  (Biernat  and  Williams 
1970).  It  is  entirely  possible  that  the  post-larval  pits  of  Tilasia  represent  a cast  of  similar  structures 
in  the  periostracum  (see  also  Williams  1990).  (3)  Most  paterinids  (like  Dictyonina  and  Micromitra) 
appear  to  have  divaricate  types  of  post-larval  pitted  ornamentation,  whereas  the  larval  shell  is 
smooth  (e.g.  Rowell  1965);  in  Dictyonites  and  Lacunites , there  are  rounded,  open  perforations, 
20-200  pm  across,  which  penetrate  the  valves  (Cooper  1956;  Wright  1981 ; Holmer  1986,  1989),  and 
the  problematic  phosphatic  brachiopod  Volborthia  (sometimes  doubtfully  referred  to  the  paterinids) 
possesses  some  kind  of  pitted,  divaricate  ornamentation,  which  has  not  been  studied  closely 
(Ushatinskaya  et  al.  1988,  pi.  6:  6a). 

Other  types  of  pitted  post-larval  ornamentation  have  been  reported  and  discussed  by  Wreight 
(1981),  Savazzi  (1986),  and  Holmer  (1986,  1987,  1989). 


SHELL  STRUCTURE 

Because  of  the  limited  material  available,  only  a single  fragment  of  the  postero-lateral  portion  of 
a dorsal  valve  was  sectioned  (Text-fig.  5).  The  rugose  exterior  of  this  fragment  is  still  covered  by  the 
calcareous  matrix  of  the  Boda  Limestone  (Text-fig.  5a). 

The  pitted  ornamentation,  described  above,  is  developed  in  the  outermost  primary  layer,  which 
is  only  about  10  pm  thick  (Text-fig.  5e).  In  etched  sections  examined  under  the  SEM,  it  has  a densely 
granular  appearance,  but  the  size  of  individual  apatite  granulae  could  not  be  determined,  and  the 
layer  appears  to  lack  birefringence.  The  boundary  to  the  secondary  layer  is  not  well  defined  (Text- 
fig.  5e),  and  the  primary  layer  is  not  easily  ‘peeled  off’  as  in  some  discinaceans  (Holmer  1987). 

The  secondary  layer  is  primarily  built  up  of  laminae,  up  to  0-3  mm  thick,  which  are  roughly 
wedge-shaped  in  section,  and  inclined  at  a low  angle  to  the  outer  valve  surface.  The  laminae  have 
a porous  appearance  both  under  the  SEM  and  the  light  microscope,  and  possess  a well-developed 
baculate  structure  (sensu  Holmer  1989),  with  criss-crossing  slender  apatite  baculae,  about  1-2  //m 
across  (Text-fig.  5b,  c).  The  detailed  internal  structure  of  the  baculae  could  not  be  determined;  they 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  5.  a.  Polished  and  etched  section  through  a fragment  of  a dorsal  valve  of  Tilasia  mgosa  sp.  nov.,  the 
location  of  b and  e indicated,  Boda  Limestone  (Ashgill),  Skalberget,  Siljan  district,  Dalarna,  SMNH 
Br  102556c,  x 27.  b,  detail  of  a,  the  location  of  c is  indicated,  x 180.  c,  detail  of  B,  x 750.  D,  detail  of  c,  x 2250. 

e,  detail  of  a,  x 1660.  F,  detail  of  E,  x 5900. 


are  covered  by  numerous  minute  apatite  granulae,  which  sometimes  are  cube-shaped,  up  to  0-5  /mi 
across  (Text-fig.  5d);  these  structures  are  possibly  related  to  secondary  cyrstal  growth  during 
diagenesis. 

In  the  inner  part  of  each  lamina  the  interbacular  spaces  are  empty,  which  causes  the  baculae  to 
stand  out  in  relief  in  etched  sections;  on  the  outer  zone,  directly  beneath  the  primary  layer,  these 
spaces  appear  to  be  filled  by  a granular  apatite  matrix  (Text-fig.  5b-d,  f).  The  thick  baculate  laminae 
are  separated  by  thin,  homogenous  lamellae,  consisting  of  minutely  granular  apatite  (Text-fig.  5b). 
The  apatite  of  the  secondary  layer  is  strongly  birefringent,  and  the  main  preferred  orientation  of  the 
c-axes  appears  to  be  roughly  normal,  or  at  a high  angle  to  the  laminae;  only  in  some  of  the  thin 
granular  lamellae  are  there  indications  of  a different  preferred  oaxis  orientation,  parallel  relative  to 
the  lamellae. 

The  shell  structure  of  Tilasia  is  nearly  indentical  to  that  of  other  Lower  Palaeozoic  lingulaceans 
discussed  by  Holmer  (1989).  The  shell  structure  of  most  Lower  Palaeozoic  lingulaceans  can  be 
interpreted  in  the  light  of  what  is  now  known  about  Recent  Glottidia , which  has  a well-defined 
primary  layer  and  a baculate  structure  penetrating  the  organic  laminae  of  the  secondary  layer  (see 
Iwata  1982;  Watabe  and  Pan  1984;  Pan  and  Watabe  1988  for  details). 

Holmer  (1987)  and  Ushatinskaya  et  al.  (1988)  noted  that  the  shell  structure  of  fossil  discinaceans 
is  comparable  with  that  of  the  lingulaceans,  and  that  they  can  also  be  compared  with  their  Recent 
representatives  (see  Iwata  1982). 

Ushatinskaya  et  al.  (1988,  p.  49;  see  also  Hewitt  1980;  Popov  and  Ushatinskaya  1986; 


HOLMER:  SWEDISH  ELKANIID  BRACHIOPOD 


203 


Ushatinskaya  and  Zezina  1988)  suggested  that  the  shell  structures  present  in  both  the  fossil  and 
Recent  phosphatic  brachiopods  could  have  been  formed  by  a complete  post-mortem  redistribution 
of  phosphate,  and  phosphatization  of  the  organic  matter  in  the  shell.  One  of  the  main  reasons  for 
this  proposal  seems  to  be  that  phosphatic,  rod-like  strutures,  somewhat  similar  to  the  brachiopod 
baculae,  have  been  described  by  Hewitt  and  Stait  (1985)  from  the  phosphatized  connecting  rings  of 
some  Ordovician  cephalopods. 

There  are  two  kinds  of  rod-like  structures  present  in  the  cephalopod  connecting  rings;  the  first 
type  apparently  represent  secondarily  phosphatized  spicules,  originally  consisting  of  aragonite 
(Hewitt  and  Stait  1985,  figs  5 and  7),  whereas  the  second  type  is  formed  by  'dendritic  granular 
crystals  on  the  interior  of  the  connecting  ring’  (Hewitt  and  Stait  1985,  fig.  2).  For  obvious  reasons, 
the  phosphatized  aragonite  spicules  are  most  unlikely  to  be  comparable  with  the  baculae  described 
from  lingulacean  and  discinacean  brachiopods.  The  second  irregular,  dendritic  pattern  of  granular 
apatite  ‘rods’  appears  to  have  grown  in  contact  with  the  surface  represented  by  the  connecting  ring, 
rather  than  representing  isolated  criss-crossing  rods  as  in  the  lingulacean  baculae.  Moreover,  the 
sections  of  Recent  Glottidia , examined  by  Iwata  (1982),  Watabe  and  Pan  (1984),  and  Pan  and 
Watabe  (1988)  were  prepared  using  freshly  killed  specimens;  it  is  highly  unlikely  that  a complete 
redistribution  of  phosphate  could  have  occurred  in  these  specimens  as  was  suggested  by 
Ushatinskaya  et  al.  (1988). 


Acknowledgements . This  study  was  carried  out  at  the  Department  of  Palaeozoology,  Swedish  Museum  of 
Natural  History,  Stockholm.  I am  grateful  to  Lennart  Andersson  (Stockholm),  who  prepared  the  art  work  and 
to  Uno  Samuelsson  (Stockholm),  who  did  the  dark  room  work.  Kristina  Lindholm  (Lund)  and  Louis  Liljedal 
(Lund)  kindly  arranged  the  loans  from  the  Tornquist  collection  (Department  of  Historical  Geology  and 
Palaeontology,  University  of  Lund).  I am  also  grateful  to  Valdar  Jaanusson  (Stockholm),  Stefan  Bengtson 
(Uppsala),  and  Sir  Alwyn  Williams  (Glasgow)  who  offered  comments  on  the  manuscript.  The  work  was 
supported  by  a grant  from  the  Swedish  Natural  Science  Research  Council. 


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in  older  inarticulate  brachiopods.  Doklady  AN  SSSR,  300,  700-703.  [In  Russian], 

- zezina,  o.  n.,  popov,  l.  e.  and  putivtseva,  n.  v.  1988.  Microstructure  and  mineral  composition  of 
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watabe,  n.  and  pan,  c.-m.  1984.  Phosphatic  shell  formation  in  atremate  brachiopods.  American  Zoologist,  24. 
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williams,  a.  1965.  Lamanskya  Moberg  and  Segerberg,  1906.  H863 . In  moore,  r.  c.  (ed.).  Treatise  on 
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L.  E.  HOLMER 

Institute  of  Palaeontology 
Box  558 

S-751  22  Uppsala,  Sweden 


Typescript  received  8 December  1989 
Revised  typescript  received  28  February  1990 


CUTICULAR  ULTRASTRUCTURE  OF  THE 
TRILOBITE  ELLIPSOCEPHALUS  POLYTOMUS 
FROM  THE  MIDDLE  CAMBRIAN  OF  GLAND, 

SWEDEN 

by  J.  E.  DALINGWATER,  S.  J.  HUTCHINSON,  H.  MUTVEI  and  D.  J.  SIVETER 


Abstract.  Hand  specimens  and  polished  sections  of  the  cuticle  of  the  trilobite  Ellipsocephalus  polytomus 
Linnarsson  from  the  Middle  Cambrian  of  Oland,  Sweden  have  been  examined  in  incident  light  and,  after 
etching,  with  the  scanning  electron  microscope.  A thin  (25-50  //m)  outer  layer  comprises  about  twenty  lamina 
units;  the  structure  of  these  units  is  interpreted  as  representing  the  original  inorganic  material  of  the  cuticle, 
and  therefore  also  reflecting  the  structure  of  the  original  organic  template.  X-ray  microanalysis  strongly 
suggests  that  this  outer  layer  is  now  composed  of  calcium  phosphate.  Cavities,  15  pm  in  diameter,  in  the  outer 
layer  connect  to  3 pm  diameter  canals  which  extend  across  the  principal  layer  of  the  cuticle:  these  resemble  the 
gland  ducts  of  a Recent  millipede.  Pore  canal  pathways  may  be  represented  by  elongate  openings  on  the 
undersurface  of  the  outer  layer,  and  structures  resembling  the  interprismatic  septa  of  Recent  decapod 
crustaceans  are  seen  in  angled  slices.  Other  primary  microstructures  identified  are  relict  organic  material  and 
fibres  which  may  have  bound  together  the  major  layers  of  the  cuticle.  Horizontal  tubules  on  the  undersurface 
of  the  outer  layer  are  possibly  infilled  borings  of  cyanobacteria. 

Major  subdivisions  of  Ellipsocephalus  cuticle  in  life  are  proposed  as:  a very  thin  outermost  epicuticle,  an 
outer  laminated  layer,  and  a principal  layer,  the  original  structure  of  which  is  represented  only  by  disc-like 
extensions  on  the  perpendicular  canals  which  pass  across  it. 

Trilobite  cuticular  microstructure  has  been  extensively  investigated  over  the  past  twenty  years 
(see  Dalingwater  1973;  Teigler  and  Towe  1975;  Dalingwater  and  Miller  1977,  Stormer  1980; 
Wilmot  and  Fallick  1989;  Wilmot  1990u),  yet  our  knowledge  of  the  overall  structure  of  the  cuticle 
is  far  from  complete,  and  the  only  detailed  information  on  ultrastructure  of  lamina  units  has  been 
provided  by  Mutvei  (1981)  from  a Flexicalymene  species  from  the  upper  Ordovician  of  Iowa. 

In  this  paper  we  describe  ultrastructural  detail  from  an  outer  cuticular  layer  of  the  Middle 
Cambrian  trilobite  Ellipsocephalus  polytomus  Linnarsson,  1877,  from  Enerum,  Oland,  Sweden, 
which  is  superior  to  anything  previously  reported  from  any  trilobite  cuticle.  We  analyze  our 
observations  in  relation  to  Recent  arthropod  material,  assess  the  implications  for  views  on  the 
overall  structure  of  the  trilobite  cuticle  and  outline  areas  for  further  investigation. 


MATERIALS  AND  METHODS 

The  collections  of  the  Naturhistoriska  Riksmuseet  in  Stockholm  contain  specimens  of  the  Middle 
Cambrian  trilobite  genus  Ellipsocephalus  preserved  in  different  lithologies:  shales,  limestones  and 
even  conglomerates.  However,  the  best-preserved  material  seems  to  be  in  the  Middle  Cambrian 
glauconitic  limestones  from  Enerum  and  Borgholm  on  the  Baltic  island  of  Oland.  Specimens  of 
Ellipsocephalus  polytomus  from  these  localities  are  almost  exclusively  cranidia,  although  the 
collections  also  include  a few  complete  dorsal  exoskeletons.  A series  of  pieces  of  glauconitic 
limestone  containing  cranidia  of  Ellipsocephalus  polytomus  and  Pciradoxides  sp.  fragments  collected 
by  Westergard  from  ‘a  boulder  at  Enerum,  Oland  in  1930’  were  selected  for  study. 

The  surface  of  the  cuticle  of  Ellipsocephalus  was  examined  and  photographed  in  incident  light. 


IPalaeontology,  Vol  34,  Part  1,  1991,  pp.  205-217,  3 pls.| 


© The  Palaeontological  Association 


206 


PALAEONTOLOGY,  VOLUME  34 


Slices  of  the  limestone,  approximately  2 mm  thick,  were  cut  away  from  blocks  of  material  with  a 
thin  high-speed  diamond  wheel,  after  one  face  had  been  flattened  on  rotating  wheels  covered  with 
carborundum-impregnated  papers  and  lubricated  with  water,  and  polished  to  a mirror  finish  using 
ultra-fine  diamond  pastes  on  felt  buffing  wheels.  Material  prepared  in  this  way  was  examined  under 
a stereo  binocular  microscope  in  incident  light.  Further  slices  prepared  in  a similar  fashion  were 
etched  in  a supersaturated  aqueous  solution  of  ethylenediaminotetracetic  acid  (disodium  salt)  for 
up  to  three  hours,  with  the  etching  process  observed  from  time  to  time  under  a stereo  binocular 
microscope  in  incident  light.  Etched  slices  were  carefully  washed  in  de-ionised  water,  air  dried,  gold 
sputter-coated  and  examined  with  a Cambridge  S360  scanning  electron  microscope  (SEM)  under 
optimum  conditions  for  high  resolution  (short  working  distance,  high  accelerating  voltage,  small 
aperture  size,  small  spot  size).  In  all,  eleven  etched  preparations  were  made  for  SEM  examination; 
each  preparation  contained  at  least  two  and  as  many  as  five  sections  of  Ellipsocephalus  cuticle,  as 
well  as  those  of  Paradoxides  sp.  Most  of  the  slices  were  deliberately  cut  in  such  a way  that  the  cuticle 
was  sectioned  more  or  less  perpendicular  to  the  cuticle  surface,  though  a few  angled  slices  were 
accidentally  produced  and  a few  deliberately  achieved.  In  addition,  an  accidental  but  fortuitous 
break  of  cuticle  along  a low  angle  from  the  horizontal  was  made;  part  and  counterpart  of  this  break 
were  examined  unetched  with  the  SEM. 

Two  further  preparations  were  carbon  coated  and  analysed  with  the  LINK  system  of  X-ray 
microanalysis  attached  to  a Cambridge  S360  SEM. 

All  preparations  are  stored  with  their  parent  specimens  (Ar  46218a-/)  in  the  Sektionen  for 
Paleozoologi,  Naturhistoriska  Riksmuseet,  Stockholm  (RM). 


DESCRIPTION  OF  THE  CUTICLE 


Terminology 

We  follow  Dennell's  (1973)  terminology  for  horizontal  laminations  of  the  cuticle:  each  lamina  unit 
is  considered  to  consist  of  a narrower  lamina  and  a wider  inter-lamina.  This  contrasts  with  the  view 
of  Bouligand  (1965)  who  considered  the  lamination  of  arthropod  cuticles  as  an  artefact  resulting 
from  the  sectioning  of  horizontal  sheets  of  fibres  with  fibre  orientation  changing  from  one  sheet  to 
the  next.  (For  a more  detailed  discussion  see  Dalingwater  and  Mutvei  1990). 

Hand  specimens 

A consistent  feature  of  Ellipsocephalus  specimens  from  Oland  is  a thin  outer  layer  which  has  a faint 
pinkish  tinge:  this  was  commented  on  by  Teigler  and  Towe  (1975,  pp.  138-139)  who  also  established 
that  a similar  thin  outer  layer  in  a Silurian  calymenid  from  Poland  was  composed  of  calcium 
phosphate,  probably  in  the  form  of  apatite. 

Specimens  of  Paradoxides  sp.,  in  the  same  beds  on  Oland  do  not  have  a thin  layer  of  this  nature. 
The  layer  does  not  completely  cover  all  parts  of  every  Ellipsocephalus  specimen:  it  is  often  worn 
away  from  the  prominence  of  the  glabella  (Text-fig  1a)  and,  in  a few  examples,  seems  to  be  absent, 
possibly  removed  on  the  counterpart.  In  the  latter  situation,  the  brown  exposed  ‘surface’  of  the 
cuticle  has  the  shiny  appearance  characteristic  of  other  well-preserved  trilobites.  It  is  possible  to  find 
two  Ellipsocephalus  cranidia  side  by  side  on  the  same  bedding  plane,  one  with  a pinkish  outer  layer, 
the  other  apparently  without.  However,  when  examined  under  a microscope,  at  least  traces  of  the 
outer  layer  can  be  found  on  all  specimens.  In  the  very  rare  ‘complete’  specimens  of  Ellipsocephalus , 
all  parts  of  the  dorsal  exoskeleton  are  seen  to  be  covered  by  the  outer  layer. 

Hand  specimens  and  polished  slices  viewed  in  incident  light 

When  the  surface  of  the  outer  layer  is  viewed  in  incident  light  at  low  magnifications,  almost  its  entire 
area  appears  to  be  patterned  with  small  circular  punctations,  about  15  pm  in  diameter  (Text-fig.  1b). 
The  spacing  of  these  punctations  is  somewhat  irregular:  in  places  they  are  almost  contiguous, 
contrasting  with  small  clear  patches,  but  on  average  they  are  15  //m  apart.  In  areas  where  the  outer 


DALINGWATER  ET  AL.\  TRILOBITE  CUTICULAR  ULTRASTRUCTURE 


207 


text-fig.  1.  Ellipsocephalus  polytomus  Linnarsson  from  Enerum,  Oland,  Sweden.  Specimen  RM  Ar  46218c. 
a,  cranidium,  x 5.  b,  detail  of  surface  punctations,  x 100. 


layer  has  been  worn  away  or  removed  on  the  counterpart,  the  punctations  can  still  clearly  be  seen, 
and  also  some  light  circular  areas  about  40  /nn  in  diameter  each  perforated  by  a minute  ( c . 1 /mi) 
opening.  These  light  circles  are  about  200  pm  apart:  a similar  spacing  to  that  of  the  patches  devoid 
of  punctations  on  the  outer  layer  surface. 

In  polished  slices,  sections  of  Ellipsocephalus  cuticle  can  easily  be  identified  by  their  shape  and  by 
the  possession  of  a thin  whitish  outer  layer,  which  at  higher  magnifications  is  seen  to  contain  darker 
spherulitic  structures  around  15  //m  in  diameter.  The  region  of  cuticle  below  the  outer  layer  is  dark 
brown  and  penetrated  by  numerous  fine  perpendicular  canals  which  stand  out  as  they  are  paler  than 
the  ground  material  of  the  inner  layer. 

SEM  preparations 

General  structure  of  the  cuticle.  The  great  predominance  of  cranidia  on  the  surface  of  the  hand 
specimens  led  us  to  assume  that  the  great  majority,  if  not  all,  of  the  Ellipsocephalus  material  was 
of  sections  of  that  part  of  the  cephalon.  As  in  material  examined  with  the  light  microscope,  the 
shape  of  many  of  the  sections  reinforced  the  validity  of  this  conclusion. 

The  etching  process  left  a thin  outer  layer,  25-50  pm  thick,  standing  clear  and  unaltered  from  the 
rest  of  the  cuticle,  up  to  200  pm  thick,  which  was  etched  inwards.  Not  only  could  the  outer  layer 
be  viewed  in  perpendicular  section,  but  its  inner  undersurface  could  also  be  examined,  for  example 
in  preparation  RM  Ar  46218fi-E4  (Text-fig.  2).  In  that  particular  preparation,  the  perpendicular 
face  clearly  shows  that  the  outer  layer  comprises  about  twenty  lamina  units,  each  just  over  1 pm 
thick.  The  majority  of  preparations  show  a similar  aspect  to  that  of  E4,  but  a few  are  different, 
possibly  the  result  of : (i)  slight  differences  in  preparation  technique,  including  direction  of  sectioning 
and  quality  of  polishing;  (ii)  original  differences  in  the  cuticles,  possibly  including  those  related  to 
the  size  of  the  animal;  (iii)  localized  diagenetic  differences.  In  preparation  RM  Ar  46218e-E9  (PI. 
1,  fig.  1),  the  outer  layer  is  somewhat  thicker  (nearly  50  pm  thick)  than  in  most  other  preparations 
and  the  lamination  is  very  clearly  defined.  There  are  about  thirty-five  lamina  units,  each  nearly 
E5  /an  thick  except  for  the  outer  five  units  which  are  thinner.  In  areas  of  a few  preparations,  for 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  2.  Scanning  electron  micro- 
graph of  etched  perpendicular  section 
of  Ellipsoceplialus  polytomus  Linnarsson 
cuticle  outer  layer,  also  with  a view  of 
undersurface  of  that  layer.  Preparation  RM 
Ar  462186-E4,  x 800. 


example  RM  Ar  462186-El  (PI.  1,  fig.  2),  the  lamination  is  less  clear  and  transforms  laterally  into 
a zone  of  semi-prismatic  calcite  crystallites,  and  in  one  preparation,  RM  Ar  462186-Ei  (PI.  1,  fig. 
3),  the  lamination  is  penetrated  by  calcite  crystallites.  Preparations  RM  Ar  462186-El  and  -Ei  are 
both  perpendicular  sections  (deduced  from  the  perpendicular  pathways  of  their  canals)  and  so  this 
transformation  or  penetration  is  a real  phenomenon  and  not  an  artefact  produced  by  angled 
sectioning. 

In  many  sections  round  or  elliptical  cavities,  up  to  1 5/mi  in  diameter  and  up  to  20  //m  high,  extend 
from  the  lower  edge  of  the  outer  layer  to  near  the  surface  of  the  cuticle.  However,  they  never  reach 
beyond  the  uppermost  fine  lamina  units,  nor  was  any  connection  between  these  cavities  and  the 
cuticle  surface  observed  in  any  of  the  sections  examined. 

Another  feature  in  many  sections  is  an  outermost  non-laminate  region  of  cuticle,  up  to  2 /mr  thick 
and  with  a dense  homogenous  appearance.  This  can  be  seen  most  clearly  in  Plate  1,  figure  1 and 
Plate  3,  figure  4. 

The  main  region  of  the  cuticle  (for  convenience  termed  the  principal  layer)  consists  of  fine 
crystallites,  presumably  of  calcite,  sometimes  with  their  long  axes  arranged  roughly  perpendicular 
to  the  cuticle  surface.  This  region  shows  little  detail  apart  from  this  feature,  but  is  penetrated  by 
perpendicular  canals,  approximately  3 /mi  in  diameter  (PI.  1,  fig.  4).  These  canals  have  disc-like 
lateral  extensions  about  0-5  //m  thick  and  on  average  the  same  distance  apart  (PI.  1,  fig.  5). 
Preparations  in  which  the  principal  layer  is  etched  deeply  inwards  illustrate  how  numerous  and 
ubiquitous  these  canals  are  (PI.  1,  fig.  6). 

Lamina  unit  ultrastructure.  At  higher  magnifications,  considerable  ultrastructural  detail  can  be 
resolved.  At  first,  a bewildering  array  of  apparently  different  structures  was  observed.  But 
eventually,  by  always  taking  micrographs  at  a standard  series  of  screen  magnifications,  it  became 
clear  that  at  least  some  of  the  apparent  variation  was  the  result  of  viewing  essentially  similar 


EXPLANATION  OF  PLATE  1 

Figs  1-6.  Ellipsoceplialus  polytomus  Linnarsson,  Middle  Cambrian,  Enerum,  Oland,  Sweden.  Scanning 
electron  micrographs  of  etched  sections  of  cranidial  cuticle.  1-3,  outer  laminated  layer  in  preparations  RM 
Ar  46218e-E9,  6-El,  6-Ei,  respectively,  all  x 650.  4-6,  perpendicular  canals  in  the  principal  layer  in 
preparations  RM  Ar  462186-E5,  x 300,  6-E5,  x 8000,  e-E9  x 250,  respectively. 


PLATE  1 


DALINGWATER  et  al.,  Ellipsocephalus  polytomus  cuticle 


210 


PALAEONTOLOGY,  VOLUME  34 


structures  at  arbitrary  magnifications,  with  slight  differences  in  preparation  method,  angle  of  slicing 
and  angle  of  viewing  also  contributing  to  variability.  Plate  2,  figure  1 shows  lamina  units  with  their 
sectional  edges  flattened  by  the  polishing  procedure,  whereas  those  in  Plate  2,  figure  2 show  a more 
broken  appearance.  The  interface  between  the  perpendicular  face  and  the  horizontal  undersurface 
of  the  outer  layer  was  also  examined  (PI.  2,  fig.  3).  In  all  three  micrographs  the  laminae  appear  to 
be  composed  of  arrays  of  rods,  with  more  or  less  circular  cross-sections,  linked  together  in  sheets; 
some  sheets  seem  to  arc  across  the  inter-laminae.  A detailed  view  of  the  undersurface  of  the  outer 
layer  (PI.  2,  fig.  4)  shows  that  the  fingerprint-like  patterns  seen  in  Text-figure  2 are  produced  by 
arced  sheets  of  fibrous  material.  A near-horizontal  view  of  a lamina  unit  in  an  unetched  break  (PI. 

2,  fig.  5)  reveals  a herringbone-like  pattern  of  rods.  In  contrast,  a near-horizontal  slice,  despite  being 
subjected  to  flattening  and  polishing  (or  perhaps  because  of  this)  shows  a mosaic  of  fibrous  and  rod- 
like material  from  different  levels  of  the  cuticle  (PI.  2,  fig.  6,  which  is  a detail  of  PI.  3,  fig.  5). 

Polygonal  patterns.  In  sub-surface  areas  of  the  unetched  preparation  viewed  from  above,  polygonal 
areas  about  40  pm  across  and  delimited  by  slightly  raised  ridges  can  be  detected  (PI.  3,  fig.  1). 

Cavities.  Round  or  elliptical  cavities  have  already  been  mentioned  as  a consistent  feature  of  the 
outer  layer  of  cuticle.  At  low  magnifications,  arrays  of  these  cavities  can  be  seen,  with  the  broken 
upper  portions  of  perpendicular  canals  below  them  (PI.  3,  fig.  4).  In  preparations  sliced  at  an  angle 
of  a few  degrees  from  the  horizontal,  the  outer  layer  is  perhaps  somewhat  disrupted  by  the  effect 
of  the  etching  process  on  the  principal  layer;  the  latter  can  be  seen  through  the  cavities  (PI.  3,  fig. 
5).  One  preparation  in  which  the  principal  layer  has  been  etched  inwards  to  a considerable  extent, 
leaving  the  outer  layer  roofing  a miniature  cave  (PI.  3,  fig.  6),  shows  the  stumps  of  canals  as  stalactic 
projections  from  the  cave  roof,  clearly  connecting  to  the  cavities  in  the  outer  layer  which  are 
‘illuminated'  by  the  electron  beam  striking  the  top  surface  of  the  cuticle  and  ‘shining  through  it’. 
On  the  right  of  the  micrograph,  a rather  stouter  perpendicular  canal  is  the  only  one  left  extending 
from  the  inner  matrix  to  the  outer  layer. 

Other  structures.  The  undersurface  of  the  outer  layer  in  some  preparations  seems  to  be  covered  by 
a thin  coating  skin  through  which  some  details  of  that  undersurface  can  still  be  seen.  This  skin  often 
peels  back  or  breaks  open  to  reveal  clearer  details.  This  phenomenon  can  just  be  seen  on  the  bottom 
right  of  Plate  1,  figure  1.  Roughly  star-shaped  arrays  of  fibrous  or  crystalline  material  (PI.  3,  fig.  2) 
stand  out  below  the  general  level  of  the  undersurface  of  the  outer  layer  in  some  preparations.  In 
some  areas  of  nearly  all  preparations,  horizontal  tubular  structures  1-2  pm  in  diameter  criss-cross 
the  undersurface  of  the  outer  layer,  sometimes  forming  node-like  structures  where  they  intersect  (PI. 

3,  fig.  3). 


COMPOSITION 

Semi-quantitative  elemental  analysis,  using  the  LINK  system  of  X-ray  microanalysis  attached  to  the 
SEM  gave  peaks  for  calcium  and  phosphorus  in  the  outer  layer,  whereas  the  principal  layer  showed 
a strong  peak  only  for  calcium  with  lesser  peaks  for  silicon  and  iron  and  only  a trace  of  phosphorus. 


EXPLANATION  OF  PLATE  2 

Figs  1—6.  Ellipsocephalus  polytomus  Linnarsson,  Middle  Cambrian,  Enerum,  Oland,  Sweden.  Scanning 
electron  micrographs  of  etched  sections  (except  5)  of  cranidial  cuticle  showing  details  of  outer  layer,  all 
x 9000.  1 and  2,  lamina  units  in  preparations  RM  Ar  46218e-E9,  b- E4.  3,  interface  between  vertical  section 
and  undersurface,  preparation  RM  Ar  462186-E4.  4,  undersurface,  preparation  RM  Ar  462186-E4.  5, 
unetched  low  angle  break,  preparation  RM  Ar  46218e-E8.  6,  low  angle  slice,  preparation  RM  Ar  462 1 8A- 
E6. 


PLATE  2 


DALINGWATER  et  a!.,  Ellipsocephalus  polytomus  cuticle 


212 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  3.  Etched  perpendicular 
section  of  Ellipsocephalus  polytomus 
Linnarsson  cuticle  outer  layer.  Left, 
scanning  electron  micrograph; 
right,  spot  X-ray  microanalysis  for 
phosphorus.  Preparation  RM  Ar 
4621 8- A2,  x 450. 


A spot  analysis  for  phosphorus  showed  an  exact  co-incidence  of  the  concentration  of  phosphorus 
with  the  outer  layer  (Text-fig.  3)  and  also  suggested  that  the  3 pm  perpendicular  canals  contain  high 
concentrations  of  phosphorus. 


DISCUSSION 


Subdivisions  of  trilobite  cuticle 

Stormer  (1980)  discussed  the  broad  divisions  of  the  trilobite  cuticle  and  generally  supported 
Dalingwater  and  Miller's  (1977)  view  that  it  consisted  of  an  outer  prismatic  layer  and  a principal 
layer  with  three  distinct  laminate  zones  - an  outer  zone  with  narrow  lamina  units,  a middle  zone 
with  a few  relatively  wide  units  and  an  inner  zone  with  a few  narrow  units.  Stormer  also  recognized 
that  rarely  are  all  regions  of  the  cuticle  equally  well  represented  or  well  preserved  in  any  one 
example.  Teigler  and  Towe  (1975)  have  argued  for  two  basic  layers  of  cuticle,  suggesting  that  the 
thin  outer  layer  may  be  prismatic  or  pigmented  or  apatitic. 

Our  interpretation  of  Ellipsocephalus  cuticle  is  that  in  life  the  outer  laminated  layer  had  only  the 
thin  apparently  structureless  outermost  layer  above  it,  the  latter  possibly  representing  an  epicuticle. 
Furthermore,  the  lateral  transition  between  laminated  cuticle  and  prismatic  cuticle  in  one 
preparation  and  the  invasion  of  the  laminated  layer  by  calcite  crystallites  in  another  suggests  that 
the  prismatic  layer  observed  in  the  cuticle  of  many  trilobites  may  not  be  an  original  layer.  However, 
much  more  evidence  is  needed  before  we  can  firmly  draw  this  conclusion. 

Ultrastructural  detail  of  lamina  units 

Calcified  cuticles  of  Recent  arthropods,  for  example  those  of  decapod  crustaceans,  have  organic 


EXPLANATION  OF  PLATE  3 

Figs  1-6.  Ellipsocephalus  polytomus  Linnarsson,  Middle  Cambrian,  Enerum,  Oland,  Sweden.  Scanning 
electron  micrographs  of  etched  sections  (except  1)  ofcranidial  cuticle.  1,  low  angle  break,  showing  prismatic 
structures,  preparation  RM  Ar  46218e-E8,  x 500.  2,  arrays  of  fibrous  material  on  outer  layer  undersurface, 
preparation  RM  Ar  462186-E4,  x 9000.  3,  tubular  structures  on  undersurface  of  outer  layer,  preparation 
RM  Ar  46218e-E9,  x 1200.  4-6,  cavities  in  the  outer  layer;  4,  perpendicular  sectional  view,  preparation  RM 
Ar  462186-Ei,  x 300;  5,  from  above,  preparation  RMAr  462186-E4,  x 1000;  6,  from  slightly  below, 
‘illuminated’  by  beam  striking  top  surface,  preparation  RM  Ar  46218e-E9,  x 300. 


PLATE  3 


DALINGWATER  et  ai,  Ellipsocephalus  polytomus  cuticle 


214 


PALAEONTOLOGY,  VOLUME  34 


templates  upon  or  within  which  inorganic  salts  are  deposited.  On  analysis,  these  templates  show  at 
least  three  levels  of  structural  organization  (Giraud-Guille  1984u).  Near-molecular  associations  of 
chitin  and  proteins  to  form  microfibrils  represent  the  first  level;  associations  of  microfibrils  in 
reticulate,  macrofibrillar  or  homogenous  arrays  form  the  second  level;  and  spatial  arrangements  of 
level  two  associations  (e.g.  macrofibrils  in  helicoidal  arrays)  give  the  third  level.  Minerals  are 
probably  deposited  within  the  reticulate  arrangement  of  microfibrils  in  the  decapod  crustacean 
exocuticle  and  around  the  macrofibres  of  the  calcified  zone;  homogenous  arrays  of  microfibrils 
effectively  fill  all  available  space  in  the  uncalcified  endocuticle.  It  is  quite  possible  to  envisage  the 
three-dimensional  arrangement  both  of  organic  template  and  deposited  minerals  in  the  decapod 
crustacean  calcified  zone  if  one  accepts  the  Bouligand-Neville  interpretation  of  laminated  cuticles. 
In  fact,  the  model  was  originally  proposed  after  examination  of  Carcinus  calcified  zone  macrofibrils 
(Bouligand  1965),  but  later  shown  to  be  more  widely  applicable  to  microfibrillar  arrangements,  for 
example  in  insect  cuticles  (Neville  1975). 

It  is,  however,  at  the  third  level  of  cuticular  architectural  organization  that  the  Dennell- 
Mutvei-Dalingwater  view  (see  Dalingwater  and  Mutvei  1990  for  a more  detailed  discussion)  does 
not  accord  with  the  Bouligand-Neville  model:  the  former  suggest  that  laminae  are  real  structures 
and  that  sheets  of  fibres  arc  across  the  inter-laminae.  In  this  context  it  is  interesting  to  note  that  it 
is  difficult  to  produce  a satisfactory  three-dimensional  helicoidal  arrangement  for  the  reticulate 
associations  of  exocuticular  microfibrils:  Giraud-Guille  (1984«,  p.  81,  fig.  6)  has  illustrated  a semi- 
helicoidal  pattern  with  fibre  direction  changing  in  blocks,  but  even  that  is  not  easily  reconciled  with 
the  reality  of  her  excellent  micrographs. 

In  Recent  decapod  crustacean  material  examined  with  the  SEM,  it  is  difficult  to  distinguish 
between  organic  template  and  deposited  minerals,  even  with  the  help  of  transmission  electron 
micrographs  of  the  same  material  in  which  all  inorganic  material  has  been  removed  by 
decalcification  prior  to  sectioning.  So  interpretation  of  lamina  unit  ultrastructure  of  the  trilobite 
material  described  here  is  extremely  difficult,  because  in  addition  to  great  structural  complexity  we 
also  have  to  consider  the  effects  of  replacement  and  diagenesis.  We  tentatively  suggest  that  in 
EUipsocephalus  the  laminae  are  composed  of  horizontal  sheets  of  rods  with  further  sheets  of  material 
arcing  at  low  angles  across  the  inter-laminae  and  connecting  adjacent  laminae.  The  rods  probably 
represent  the  original  inorganic  material  of  the  cuticle,  and  possibly  also  reflect  the  original  organic 
template. 

Significance  of  a finely  laminated  outer  cuticular  layer 

Many  extant  arthropods  from  all  the  major  groups  (crustaceans,  insects,  chelicerates)  have  an  outer 
cuticular  layer  with  fine  lamina  units  - invariably  much  finer  than  those  in  central  regions  of  their 
cuticles.  This  outer  layer  is  very  likely  to  have  been  formed  pre-ecdysially,  i.e.  under  the  old  cuticle 
prior  to  moulting,  whereas  central  and  inner  regions  of  the  cuticle  are  usually  formed  after  ecdysis. 
Possibly  slower  pre-ecdysial  formation  in  some  ways  results  in  the  formation  of  narrow  lamina 
units,  but  perhaps  a functional  explanation  is  more  likely.  A region  of  narrow  lamina  units  on  the 
outside  of  a cuticle  will  have  considerable  crack-stopping  ability.  This  holds  good  with  lamination 
interpreted  either  according  to  the  Bouligand-Neville  model  or  the  Dennell-Mutvei-Dalingwater 
explanation  (for  further  discussion  see  Dalingwater  1985,  p.  360). 

Cavities  and  caned s 

The  cavities  in  the  outer  layer  appear  circular  or  egg-shaped  in  many  perpendicular  sections,  but  a 
few  are  pear-shaped  with  the  narrower  end  pointing  upwards.  Only  in  sections  close  to  their  mid- 
line  do  pear-shaped  structures  reveal  their  true  shape;  glancing  slices  will  appear  round  or  oblong. 
We  therefore  suggest  that  the  most  complex  aspect  seen  reflects  the  true  shape  - resembling  that  of 
an  upwardly  pointing  pear.  The  3 pm  canals  which  characterize  the  principal  layer  connect  the 
cavities  to  the  inner  surface  of  the  cuticle  and  therefore  originally  to  the  epidermis.  On  the  other 
hand,  the  cavities  do  not  quite  extend  to  the  surface  of  the  cuticle,  nor  do  they  appear  to  be 
connected  to  the  surface.  However,  they  extend  so  close  to  the  surface,  that  in  hand  specimens 


DALINGWATER  ET  AL.\  TRILOBITE  CUTICULAR  ULTRASTRUCTURE 


215 


illuminated  from  above  they  can  be  seen  through  the  thin  (less  than  10  //m)  overlying  layer  of 
cuticle.  Furthermore,  slight  abrasion  will  easily  remove  this  overlying  layer  and  expose  the  tops  of 
cavities. 

These  cavities  and  canals  are  similar  in  position  and  dimensions  to  the  Osmolska  cavities 
described  and  discussed  in  great  detail  by  Stormer  (1980).  Stormer  considered  that  this  type  of 
cavity  occurred  below  the  prismatic  layer,  but  Wilmot  (1990/?)  has  clearly  shown  that  they  usually 
occur  within  the  prismatic  layer.  Stormer  (1980)  suggested  a chemosensory  function  for  the 
Osmolska  cavities,  whereas  Wilmot  (19906)  preferred  to  interpret  the  cavities  and  canals  as  some 
type  of  modified  pore  canal.  However,  the  most  closely  analogous  structures  to  the  cavities  and 
canals  that  we  have  encountered  in  an  extensive  search  through  the  literature  are  the  gland  ducts 
of  the  millipede  Glomeris  convexa  which  have  dilated  tips  within  a finely-laminated  outer  region  of 
cuticle  (Richards  1951,  p.  55,  fig.  32c).  Gland  ducts  may  be  concerned  with  the  secretion  and 
maintenance  of  the  epicuticle.  The  dilated  tips  of  the  gland  ducts  in  Glomeris  are  shown  to  connect 
to  the  surface  of  the  cuticle  by  minute  canals.  As  mentioned  above,  we  have  not  detected  such 
openings  in  Ellipsocephalus , but  connections  to  the  surface  by  minute  canals  would  show  up  only 
very  rarely  in  sectional  slices. 

The  canals  in  the  endocuticle  of  Flexicalymene  which  Mutvei  (1981,  p.  230,  fig.  5)  termed  pore 
canals  have  a diameter  of  about  0-3  //m,  similar  to  that  of  the  pore  canals  in  Recent  arthropod 
cuticles,  and  do  not  connect  to  cavities.  They  do,  however,  show  a feature  of  similarity  with  the 
canals  in  Ellipsocephalus'.  disc-like  lateral  extensions  which  Mutvei  called  horizontal  lamellae  or 
laminae.  They  almost  certainly  reflect  ultrastructural  elements  of  the  principal  layer,  but  whether 
they  represent  the  laminae  themselves  or  structures  within  lamina  units  is  uncertain. 

Mutvei  (1981,  p.  229,  fig.  4)  described  wider  ducts,  3-7  //m  in  diameter,  in  Flexicalymene  cuticle. 
There  may  also  be  two  types  of  canal  in  Ellipsocephalus  cuticle : the  great  majority  are  the  3 pm 
diameter  canals  which  connect  to  cavities,  but  slightly  wider  canals  which  do  not  connect  to  cavities 
(e.g.  to  the  right  in  PI.  3,  fig.  6)  may  account  for  the  irregularities  in  the  spacing  of  punctations  as 
seen  in  surface  views  of  hand  specimens  and  the  presence  of  light  circular  areas  on  worn  surfaces 
of  hand  specimens. 

Absence  from  the  outer  layer  of  any  structures  that  can  definitely  be  regarded  as  pore  canals  is 
puzzling.  In  an  outer  (and  presumably  pre-ecdysially  formed)  layer  of  cuticle  a supply-line  for 
minerals  and  for  other  materials  required  for  mineralization  would  be  needed  after  ecdysis.  In 
Recent  decapod  crustacean  cuticles  pore  canals  almost  certainly  carry  out  this  function  (Roer  and 
Dillaman  1984).  However,  pore  canals  are  essentially  organic  structures,  so  they  may  not  necessarily 
be  preserved  as  canals.  Elliptical  openings  are  present  on  the  undersurface  of  the  outer  layer  (PI.  2, 
fig.  4)  reminiscent  of  pore  canal  pathways:  thus  pore  canals  may  indeed  originally  have  passed 
upwards  through  the  Ellipsocephalus  cuticle  outer  layer. 

Significance  of  other  primary  microstructures 

Polygonal  structures  observed  at  a sub-surface  level  in  the  outer  laminated  layer  (PI.  3,  fig.  1)  may 
be  equivalent  to  the  interprismatic  septa  of  calcified  cuticles  of  Recent  decapod  crustaceans.  The 
walls  of  the  septa  in  these  Recent  cuticles  represent  cell  margins  transformed  into  cuticular  material 
and  show  concentrations  of  cation-binding  glycoproteins  and  maximum  carbonic  anhydrase 
activity  (Giraud-Guille  19846).  Thus  the  walls  represent  sites  of  calcification  initiation.  It  is 
important  to  note  that  they  do  not  extend  to  the  surface  of  the  cuticle  and  are  therefore  distinct  from 
polygonal  surface  ornament  whose  shapes  and  sizes  are  not  necessarily  related  to  epidermal  cell 
shapes.  Giraud-Guille  (19846)  has  clearly  shown  that  interprismatic  septa  coincide  precisely  with 
underlying  epidermal  cells. 

The  thin  coating  skin  (PI.  1 , fig.  1 ) on  the  undersurface  of  the  outer  layer  may  represent  a deposit 
of  relict  organic  material  from  the  dissolution  of  the  principal  layer.  Relict  organic  material  has  been 
identified  in  other  trilobite  cuticles  by  Dalingwater  (1973)  and  Teigler  and  Towe  (1975). 

The  roughly  star-shaped  arrays  also  on  the  undersurface  of  the  outer  layer  (PI.  3,  fig.  2)  may  be 
the  remains  of  fibrous  structures  binding  together  this  and  the  underlying  principal  layer.  Dennell 


216 


PALAEONTOLOGY,  VOLUME  34 


(1973)  identified  horizontal  arrays  of  fibres  in  decapod  crustacean  cuticles  which  he  suggested  might 
bind  together  adjacent  lamina  units. 

Secondary  microstructures 

The  1-2  /mi  horizontal  tubules  on  the  undersurface  of  the  outer  layer  (PI.  3,  fig.  3)  are  interpreted 
as  secondary  structures  because  they  are  irregular  in  appearance  and  inconsistent  with  other 
cuticular  structures  in  their  arrangement.  They  are  remarkably  similar  in  dimensions  and 
appearance  to  borings  described  by  Runnegar  (1985)  from  shells  of  the  gastropod  Yuwenia  bentleyi 
from  the  Lower  Cambrian  Pavara  Limestone  of  South  Australia.  Runnegar  concluded  that  these 
borings  were  made  by  cyanobacteria  rather  than  by  fungi.  Although  the  nodal  structures  in  the 
tubules  in  Ellipsocephalus  could  be  interpreted  as  fungal  reproductive  bodies,  in  other  aspects  the 
resemblance  to  the  borings  described  by  Runnegar  is  so  close  that  it  seems  reasonable  to  consider 
the  tubules  in  Ellipsocephalus  also  as  infilled  borings  of  cyanobacteria. 


Composition  of  the  cuticle  in  Ellipsocephalus 

Although  the  outer  layer  is  now  almost  certainly  composed  of  calcium  phosphate  in  the  form  of 
apatite  and  the  principal  layer  (except  for  the  3 pm  canals)  of  calcium  carbonate  in  the  form  of 
calcite,  it  is  uncertain  if  this  reflects  the  original  composition.  Teigler  and  Towe  (1975)  did,  however, 
demonstrate  a high  concentration  of  phosphorus  in  an  outer  layer  of  a Recent  crab  cuticle.  One 
suggestion  that  we  can  make  at  this  stage  is  that  the  outer  layer  may  originally  have  had  a different 
composition  from  the  principal  layer,  since  detailed  microstructures  are  preserved  in  the  former  but 
not  in  the  latter  except  as  discs  around  perpendicular  canals.  Alternatively,  the  outer  layer  could 
have  had  a different  structure  from  the  principal  layer  which  was  more  predisposed  to  replacement ; 
preferential  replacement  could  have  resulted  in  better  preservation  of  microstructural  detail. 

We  intend  to  make  further  studies  of  the  composition  of  the  cuticle  employing  a range  of 
techniques  including  cathodoluminescence. 


Concluding  remarks 

Ultrastructural  details  described  here  from  Ellipsocephalus  cuticle  are  the  finest  so  far  from  any 
trilobite  cuticle  and  it  is  ironic  that  they  are  possibly  also  the  oldest  such  details  described  from  any 
arthropod  cuticle.  But,  before  any  firm  conclusions  can  be  drawn  about  the  general  structure  of 
trilobite  cuticle,  more  work  is  needed  on  a range  of  cuticles  using  careful  preparation  techniques  and 
taking  advantage  of  the  increased  resolution  of  the  current  generation  of  SEMs.  Parallel  studies  of 
Recent  crustacean  cuticles  are  also  needed  to  elucidate  the  precise  positional  relationships  of  organic 
template  and  inorganic  impregnating  minerals.  There  are  signs  that  arthropod  cuticle  workers  are 
at  last  breaking  out  of  the  straightjacket  imposed  by  the  Bouligand-Neville  model  of  cuticular 
architecture  (Neville  1975).  Compere  and  Goffinet  (1987a,  b ),  for  example,  have  described  new  and 
exciting  structural  details,  from  decapod  crustacean  cuticles,  which  do  not  fit  the  model.  We  need  to 
know  about  and  to  be  able  to  explain  the  reasons  for  differences  between  the  cuticles  of  different 
species  and  of  higher  taxa,  as  well  as  attempting  to  identify  features  of  similarity. 

The  significance  of  the  work  described  and  discussed  here  is  not  only  in  the  discovery  of  such 
exceptionally  fine  details  in  a trilobite  cuticle,  but  also  in  heralding  a new  phase  of  fossil  arthropod 
cuticle  research  made  possible  by  new  techniques  and  new  instruments. 


Acknowledgements.  We  thank  the  staff  of  the  School  of  Biological  Sciences  Electron  Microscope  Unit  for  their 
help,  advice  and  technical  expertise.  We  are  most  grateful  to  Dr  Paul  Selden  for  his  constructive  comments  on 
a preliminary  version  of  the  manuscript,  Mr  Les  Lockey  for  photographic  work  and  Miss  Lisa  Monks  for 
typing  the  final  copy.  This  study  was  financially  supported  by  Grant  287-1 18  of  the  Swedish  Natural  Science 
Research  Council. 


DALINGWATER  ET  AL.\  TRILOBITE  CUTICULAR  ULTRASTRUCTURE 


217 


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Compte  Rendu  Hebdomadaire  des  Seances  de  I'Academie  des  Sciences,  Paris,  261,  3665-3668. 
compere,  p.  and  goffinet,  g.  1987a.  Ultrastructural  shape  and  three-dimensional  organization  of  the 
intracuticular  canal  systems  in  the  mineralized  cuticle  of  the  green  crab  Carcinus  maenas.  Tissue  and  Cell , 
19,  839-857. 

- 19876.  Elaboration  and  ultrastructural  changes  in  the  pore  canal  system  of  the  mineralized  cuticle 
of  Carcinus  maenas  during  the  moulting  cycle.  Tissue  and  Cell , 19,  859-875. 
dalingwater,  j.  E.  1973.  Trilobite  cuticle  microstructure  and  composition.  Palaeontology , 16,  827-839. 

- 1985.  Biomechanical  approaches  to  eurypterid  cuticles  and  chelicerate  exoskeletons.  Transactions  of  the 
Royal  Society  of  Edinburgh  ( Earth  Sciences ),  76,  359-364. 

- and  miller,  j.  1977.  The  laminae  and  cuticular  organisation  of  the  trilobite  Asaphus  raniceps. 
Palaeontology,  20,  21-32. 

- and  mutvei,  h.  1990.  Arthropod  exoskeletons.  83-96.  In  carter,  j.  g.  (ed.).  Skeletal  biomineralization : 
patterns , processes  and  evolutionary  trends.  Van  Nostrand  Reinhold,  New  York,  399  pp. 

dennell,  r.  1 973.  The  structure  of  the  cuticle  of  the  shore-crab  Carcinus  maenas  (L. ).  Zoological  Journal  of  the 
Linnean  Society , 52,  159-163,  5 pis. 

giraud-guille,  M.-M.  1984a.  Fine  structure  of  the  chitin-protein  system  in  the  crab  cuticle.  Tissue  and  Cell,  16, 
75-92. 

- 19846.  Calcification  initiation  sites  in  the  crab  cuticle:  The  interprismatic  septa.  An  ultrastructural 
cytochemical  study.  Cell  and  Tissue  Research,  236,  413-420. 

linnarsson,  j.  G.  o.  1877.  Om  faunan  i lagran  med  Paradoxides  olandicus.  Sveriges  Geologiska  Undersokning. 

Afhandlingar  och  Uppsatser,  Stockholm,  Series  C,  No.  22,  1-24,  pis  1,  2. 
mutvei,  h.  1981.  Exoskeletal  structure  in  the  Ordovician  trilobite  Fie xicaly metre.  Lethaia,  14,  225-234. 
Neville,  a.  c.  1975.  Biology  of  the  arthropod  cuticle.  Springer-Verlag,  Berlin,  Eleidelberg,  New  York,  xvi  + 448 

pp. 

richards,  a.  G.  1951.  The  integument  of  arthropods.  University  of  Minnesota  Press,  Minneapolis,  xvi  + 41 1 pp. 
roer,  r.  and  dillaman,  r.  1984.  The  structure  and  calcification  of  the  crustacean  cuticle.  American  Zoologist, 
24,  893-909. 

runnegar,  b.  1985.  Early  Cambrian  endolithic  algae.  Alcheringa,  9,  179-182. 

stgrmer,  l.  1980.  Sculpture  and  microstructure  of  the  exoskeleton  in  chasmopinid  and  phacopid  trilobites. 
Palaeontology,  23,  237-271. 

teigler,  d.  j.  and  towe,  k.  m.  1975.  Microstructure  and  composition  of  the  trilobite  exoskeleton.  Fossils  and 
Strata,  4,  137-149,  9 pis. 

wilmot,  n.  v.  1990a.  Cuticular  structure  of  the  agnostine  trilobite  Homagnostus  obesus.  Lethaia,  23,  87-92. 

- 19906.  Primary  and  diagenetic  microstructures  in  trilobite  exoskeletons.  Historical  Biology,  4,  51-65. 

- and  fallick,  a.  e.  1989.  Original  mineralogy  of  trilobite  exoskeletons.  Palaeontology,  32,  297-304. 

j.  e.  dalingwater  and  s.  j.  hutchinson 

Department  of  Environmental  Biology 
The  University,  Manchester  M13  9PL,  UK 

H.  MUTVEI 

Sektionen  for  Paleozoologi 
Naturhistoriska  Riksmuseet 
104  05  Stockholm,  Sweden 

D.  J.  SI  VETER 

University  Museum 
Parks  Road,  Oxford  OX1  3PW,  UK 


Typescript  received  27  January  1990 
Revised  typescript  received  23  February  1990 


CONTRASTING  FEEDING  STRATEGIES  IN 
BIVALVES  FROM  THE  SILURIAN  OF  GOTLAND 

by  LOUIS  LILJEDAHL 


Abstract.  Two  examples  of  contrasting  feeding  strategies  in  bivalves  from  the  Silurian  of  Gotland  are 
presented.  The  first  shows  a deposit-feeding  community  of  protobranchs  in  which  non-siphonate  species 
greatly  dominate  siphonate  ones.  This  is  probably  the  result  of  extensive  bioturbation  by  the  non-siphonate 
species  causing  agitation  of  the  fine-grained  sediment  and  consequent  disturbance  of  the  feeding  of  siphonate 
species.  Tiering  of  this  community  is  also  suggested,  based  on  observations  on  abundant,  silicified  material.  The 
second  example  depicts  shallow  subtidal  life  associations  of  Ilionia  prisca  in  preferred  orientation.  This  species 
shows  special  characteristics  typical  of  extant  deeply  burrowing  suspension-feeders  of  the  superfamily 
Lucinacea.  It  is  suggested  that  Ilionia  prisca  had  a unique  feeding  strategy  of  anterior  inhalation  through  a 
mucus  tube,  and  also  that  it  oriented  itself  obliquely  to  the  direction  of  wave  action,  both  for  optimal  intake 
of  suspended  food  particles  and  for  the  avoidance  of  inhaling  its  own  waste  products.  Possibly  Ilionia  prisca 
also  lived  in  symbiosis  with  sulphur-oxidizing  bacteria.  The  beds  discussed  are  intercalated  with  shales  and  it 
is  assumed  that  the  whole  bivalve  population  was  instantaneously  killed  off  when  smothered  by  mud. 


Bivalves  are  perhaps  the  most  thoroughly  investigated  of  all  marine  invertebrates  and  many 
studies  have  been  devoted  to  the  feeding  habits  of  this  group.  Throughout  their  evolutionary 
history,  bivalves  have  occupied  a large  spectrum  of  aquatic  habitats  and  are  thus  well  suited  for 
palaeoecological  reconstructions. 

The  feeding  habits  and  trophic  relations  of  benthic  invertebrates  have  been  classified  by  various 
workers  in  different  ways  (e.g.  Stanley  1968;  Walker  and  Bambach  1971).  Most  bivalves  are 
generally  considered  to  be  suspension  feeders  or  deposit  feeders  or  carnivores.  The  classification  of 
organisms  as  true  suspension  feeders  or  true  deposit  feeders,  however,  is  made  difficult  by  the 
presence  of  ‘opportunistic  feeders’,  i.e.  those  capable  of  using  more  than  one  feeding  method 
(Cadee  1984). 

Deposit  feeders  ingest  organic  matter  trapped  in  the  substrate  in  which  they  live  and  therefore 
must  actively  move  about  in  search  of  food.  Their  gills  are  simply  built  and  mainly  used  for 
respiration,  while  the  collection  of  food  particles  is  provided  by  palp  proboscides.  Siphons,  when 
present,  are  used  for  respiration  (Cox  1969). 

The  protobranchs  discussed  in  this  paper  include  one  opportunistic  deposit  feeder,  the  solemyoid 
Janeia  silurica  (believed  to  have  been  symbiotic  with  chemoautotrophic  bacteria:  see  Liljedahl 
1984a,  19846,  1984c). 

In  suspension  feeders,  the  gills  are  more  complex  than  those  of  the  deposit  feeders  and  are  mainly 
used  for  food  collection.  Suspension  feeders  normally  remain  fixed  in  one  position  and  passively 
feed  on  particles  which  come  to  them  through  the  water.  When  present,  siphons  are,  in  contrast  with 
the  deposit  feeders,  used  for  feeding.  Also  within  the  suspension  feeders  ‘opportunistic’  feeders  are 
present.  The  Silurian  Ilionia  prisca  is  assumed  to  have  lived  in  symbiosis  with  chemoautrophic 
bacteria  and  is  thus  considered  an  ‘opportunistic’  filter  feeder  (Liljedahl  in  prep.). 

Bivalves  play  an  important  role  in  the  tiering  relationships  (relative  vertical  (ecological)  positions 
of  organisms  within  a community)  in  many  Recent  biotas,  where  different  trophic  categories  or 
feeding  groups  may  be  recognized  (Ausich  and  Bottjer  1984). 

The  chemical  stratification  and  related  environmental  changes  within  a sediment  may  be 

(Palaeontology,  Vol  34,  Part  1,  1991,  pp.  21 9-235. | © The  Palaeontological  Association 


220 


PALAEONTOLOGY,  VOLUME  34 


considerable.  Accordingly,  the  ecological  relationships  of  organisms  downwards  from  the  surface 
can  be  more  extreme  below  the  sediment/water  interface  than  above  it. 

The  first  example  considered  in  the  present  paper,  is  represented  by  deposit  feeders.  In  this, 
community  tiering  may  be  established  (for  detailed  analysis  see  Liljedahl  1985).  Indirect 
competitive  interactions  may  also  have  been  present  here:  the  feeding  habits  of  one  trophic  group 
(the  non-siphonate  deposit  feeders)  is  suggested  to  have  made  the  substrate  unsuitable  for 
representatives  of  another  trophic  group,  the  siphonate  deposit  feeders  (see  Rhoads  and  Young 
1970;  Levinton  and  Bambach  1975). 

As  filterers,  suspension  feeders  are  sensitive  to  sudden  environmental  changes  (in  contrast  to 
deposit  feeders).  Above  the  sediment/water  interface,  ecological  stratification  may  also  occur, 
depending  on  different  susceptibility  to  fouling  among  the  suspension  feeders. 

The  second  example  is  provided  by  the  deeply  buried  ‘opportunistic’  suspension  feeder  Ilionia 
prisca  (Hisinger).  It  inhabited  a substrate  of  low  species  diversity  in  a shallow  subtidal  environment 
of  low  oxygen  and  high  sulphur  content,  unsuitable  for  most  other  bivalves.  It  is  suggested  that 
Ilionia  prisca  oriented  itself  with  its  anterior-posterior  axis  obliquely  to  wave  movement,  i.e.  with 
its  anterior  inhalant  mucus  tube  against  the  flow  of  suspended  food  particles.  By  analogy  with  its 
living  relatives  (Reid  and  Brand  1986)  it  is  also  assumed  that  Ilionia  prisca  housed  chemoautotrophic 
bacteria  in  the  gills,  the  bacteria  being  important  nutritional  providers  for  the  bivalve  (Liljedahl  in 
prep.). 

INTERACTIONS  BETWEEN  THE  DEPOSIT-FEEDING  BIVALVES  OF  MOLLBOS 

The  material  from  Mollbos  1 consists  of  2743  silicified  valves,  of  which  684  are  articulated.  Only 
one  specimen  (Nuculodonta  gotlandica)  has  been  observed  in  life-position  (Text-fig.  1g).  They  were 
all  isolated  by  acid  etching  and  the  preferred  life-positions  of  each  of  the  Mollbos  species  are  thus 
mainly  based  on  morphological  and  statistical  grounds  by  analogy  with  modern  counterparts. 

One  of  the  advantages  of  the  acid  etching  method  is  that  the  whole  preserved  shelly  fauna  is 
recovered,  i.e.  all  sizes  are  represented  (Liljedahl  1984a).  Above  all  it  is  possible  to  obtain  enough 
material  for  fairly  reliable  statistical  processing  (Liljedahl  1985). 

The  bivalves  form  an  important  constituent  of  the  Mollbos  fauna.  Although  it  is  a typical  soft- 
bottom  community,  this  fauna  contains  a conspicuous  amount  of  sessile  benthos  such  as 
stromatoporoids,  tabulate  corals,  rugose  corals,  crinoids,  etc.  probably  due  to  close  vicinity  to  a 
reef.  It  abounds  in  infaunal  burrowers,  e.g.  protobranch  bivalves,  gastropods,  and  annelid  worms 
(Liljedahl  1983).  f 

The  Wenlockian  Halla  Beds  at  Mollbos  consists  of  a compact,  strongly  argillaceous  calcilutite 
which  is  fairly  hard  due  to  silicification  (Liljedahl  1983,  p.  8).  The  high  percentage  of  deposit  feeding 


text-fig.  1.  a,  Nuculoidea  lens.  External  dorsal  view  of  articulated  specimen,  anterior  to  the  left,  SGU  TYPES 
894,  895,  sample  G77-28LJ,  x4-3.  b,  Nuculodonta  gotlandica.  External  dorsal  view  of  articulated  specimen, 
anterior  to  the  left,  SGU  TYPES  1202,  1203,  sample  G79-82LJ,  x 3-9.  c,  Nuculoidea  lens.  External  lateral  view 
of  a left  valve,  SGU  TYPE  901,  sample  G77-28LJ,  x 3 9.  d,  Nuculodonta  gotlandica.  External  lateral  view  of 
a left  valve,  SGU  TYPE  1036,  sample  G78-2LL,  x4-4.  e,  Nuculoidea  lens.  Internal  postero-ventral  view  of 
holotype  (right  valve)  showing  from  left  to  right,  anterior  adductor  muscle  scar,  anterior  pedal  protractor 
muscle  scar  (first  arrow  from  the  left),  visceral  attachment  muscle  scar  (second  arrow),  anterior  pedal  retractor 
muscle  scar  (third  arrow),  and  pedal  elevator  muscle  scar  (fourth  arrow),  SGU  TYPE  842,  sample  G77-28LJ, 
x 3-5.  F,  Nuculodonta  gotlandica.  Internal  posteroventral  view  of  a right  valve  showing  from  left  to  right, 
anterior  adductor  muscle  scar,  anterior  pedal  protractor  muscle  scar  (first  arrow  from  the  left),  anterior  pedal 
retractor  muscle  scar  (second  arrow),  and  visceral  attachment  muscle  scar  (third  arrow),  SGU  TYPE  1200, 
sample  G79-82LJ,  x 4.  g,  Nuculodonta  gotlandica.  Only  specimen  of  the  bivalve  fauna  of  Mollbos  1 found  in 
life-position,  just  below  original  sediment  surface,  LO  6084t,  loose  boulder,  x 1-3.  All  specimens  are  silicified 

and  all  samples  are  from  Mollbos  1. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


221 


text-fig.  1 . For  legend  see  opposite. 


222 


PALAEONTOLOGY,  VOLUME  34 


animals  suggests  that  this  sediment  was  rich  in  bacteria,  as  is  often  the  case  in  fine  grained  substrates 
(Zobell  1938:  Newell  1970). 

It  is  concluded  that  the  Mollbos  infaunal  bivalve  fauna  is  autochthonous  and  undisturbed  except 
for  post  mortem  phenomena,  such  as  disturbances  by  scavengers  and  burrowing  deposit  feeders 
(Liljedahl  1985;  also  see  Johnson  1960  for  criteria  for  life  associations). 

The  bivalve  fauna  is  numerically  dominated  by  deposit  feeding  species  (90%  of  the  bivalve 
population:  Liljedahl  1985).  It  comprises  four  nuculoid  species,  Nuculodonta  gotlandica  Liljedahl, 
1983  (44%  of  Mollbos  bivalves),  Nuculoidea  lens  Liljedahl,  1984  (27%),  Palaeostraba  baltica 
Liljedahl,  1984  (0-7%),  Caesariella  lindensis  (Soot-Ryen,  1964)  (0-4%),  and  one  solemyoid,  Janeia 
silurica  Liljedahl,  1984  (18%). 

Shell  morphology  of  the  different  deposit  feeding  bivalves  shows  a common  theme  with  minor 
variations  (Liljedahl  1 984<r/).  The  impressions  of  pedal  and  other  accessory  muscles  are  evident 
(Text-fig.  1e,  f)  and  the  anterior  part  of  the  shell  is  large,  indicating  a strong  and  functional 
burrowing  foot  (see  reconstructions  in  Text-fig.  3).  Also  the  adductor  muscle  scars  are  generally 
deep,  suggesting  powerful  closing,  and  thus  efficient  removal  of  debris  and  other  indigestible 
material  from  the  mantle  cavity.  Much  of  the  space  of  the  mantle  cavity  was  probably  occupied  by 
the  foot  and  its  muscles,  whereas  the  gills  most  probably  were  moderate  in  size  (note  the  opposite 
relation  in  stationary  suspension-feeding  species). 

Shell  morphology  indicates,  in  combination  with  statistical  data,  a probable  life  position  in  the 
substrate  as  shown  in  Text-figure  3.  Nuculodonta  gotlandica  has  a thick,  robust  shell,  deep  adductor 
muscle  scars,  prominent  pedal  muscles  scars,  and  lacks  any  indication  of  siphons  (Text-fig.  1b,  d, 
f,  g).  Its  shell  shape  suggests  a moderately  slow  rate  of  burrowing,  (Liljedahl  1984a,  fig.  4). 
Accordingly,  it  is  proposed  that  it  lived  close  to  the  sediment/water  interface  (Text-fig.  3). 

Nuculoidea  lens  has  a somewhat  thinner  shell,  deep  adductor  muscle  scars,  clear  pedal  muscle 
scars  and  no  indication  of  siphons  (Text-fig.  1a,  c,  e).  The  shell  shape  suggests  a moderately  slow 
rate  of  burrowing  (Liljedahl  1984a,  fig.  4).  Most  probably  it  lived  somewhat  deeper  in  the  substrate 
than  Nuculodonta  gotlandica  (Text-fig.  3 ; conclusion  partly  based  on  articulated  valves  relative  to 
disarticulated  valves;  see  next  section). 

Janeia  silurica  has  a thin,  elongate  and  compressed  shell  and  deep  adductor  muscle  scars  (Text- 
fig.  2e-g),  all  features  typical  of  a rapidly  burrowing  bivalve  (see  Liljedahl  1984a,  fig.  4,  19846). 
Although  fragmented  (due  to  its  thin  shell),  a considerable  number  of  specimens  are  articulated 
(31  %).  Furthermore,  the  configuration  of  the  muscular  impressions  suggests  that  it  may  have  lived 
symbiotically  with  chemo-autotrophic  bacteria  at  a sulphide-rich  level  of  the  bottom  (see 
Cavanaugh  et  al.  1981)  where  it  did  not  have  to  compete  for  food  with  other  species  (Liljedahl 
19846).  Thus,  it  seems  that  of  all  bivalves  of  this  community  Janeia  silurica  inhabited  the  deepest 
level  (Text-fig.  3). 

All  three  species  have  an  anteriorly  expanded  shell  and  a well  developed  system  of  pedal  muscle 
scars,  just  as  in  extant  forms  capable  of  active  burrowing. 

Palaeostraba  baltica,  has  a thin  shell  with  a shape  suggesting  rapid  burrowing  (Text-fig.  2b,  d; 
Liljedahl  1984a,  fig.  4).  It  also  has  a posterior  sulcus  indicating  the  presence  of  siphons.  Both 
characters  suggest  that  it  lived  at  a position  somewhat  below  the  sediment  surface  (Text-fig.  3). 

Caesariella  lindensis  has  a thin  shell  and  a shallow  pallial  sinus  containing  siphonal  retraction 
muscle  scars,  which  indicates  the  presence  of  siphons.  Its  shell  form  suggests  slow  burrowing  (Text- 
fig.  2a,  c:  Liljedahl  1984a,  fig.  4)  and  its  life  position  is  thought  to  have  been  just  below  the  sediment 
surface  (Text-fig.  3). 

The  two  last  mentioned  species  have  conspicuous,  but  not  especially  deep,  scars  of  pedal  muscles 
suggesting  fairly  good  burrowing  ability. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


223 


text-fig.  2.  a,  Caesariella  lindensis.  External  lateral  view  of  right  valve  specimen  of  holotype,  SGU  TYPE 
3606,  sample  G79-78LJ,  x 3-4.  b,  Palaeostraba  baltica.  External  lateral  view  of  holotype  (left  valve),  note 
posterior  sulcus  (at  arrows),  SGU  TYPE  3498,  sample  G78-2LL,  x 4-3.  c,  Caesariella  lindensis.  Internal  lateral 
view  of  left  valve  specimen  of  holotype,  SGU  TYPE  3607,  sample  G79-78LJ,  x 3 4.  d,  Palaeostraba  baltica. 
Internal  lateral  view  of  holotype,  x 4.  e-g,  Janeia  silurica;  e,  external  dorsal  view  of  articulated  specimen, 
anterior  to  the  right,  SGU  TYPES  3426,  3427,  sample  G77-29LJ,  x T8;  f,  external  lateral  view  of  articulated 
specimen,  anterior  to  the  right,  same  specimen  as  e,  x T7;  g,  internal  lateral  view  of  right  valve  specimen  of 
holotype,  SGU  TYPE  3608,  sample  G79-79LJ,  x 2-4.  All  specimens  are  silicified  and  all  samples  are  from 

Mollbos  1. 

TIERING  OF  THE  MOLLBOS  BIVALVE  COMMUNITY 

Nuculodonta  gotlandica  makes  up  50  0%  of  the  counted  2743  protobranch  valves  (protobranch  shell 
debris  estimated  as  double  that  amount),  Nuculoidea  lens  28-7  %,  Janeia  silurica  19-9  %,  Palaeostraba 
baltica  0-9%,  and  Caesariella  lindensis  0 4%. 


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PALAEONTOLOGY,  VOLUME  34 


1cm 


b 


c 


text-fig.  3.  Suggested  life-position  and  reconstructions  of  the  foot  and  gills  of  the  protobranchs  of  Mollbos. 
Arrows  indicate  in-  and  exhalant  currents,  respectively,  a,  b,  and  c represent  different  tiers.  Maximum  depth 

approx.  7 cm.  Sizes  relative  to  each  other. 

Seventeen  samples  were  taken  from  seventeen  beds  in  three  vertical  sections  about  ten  metres 
apart.  Due  to  faulting,  however,  these  can  not  be  correlated  (Liljedahl  1984u,  p.  82).  The  species 
ranking  is  shown  in  Text-figure  4. 

Nuculodonta  gotlandica  is  ranked  first  in  sixteen  samples  and  second  in  one.  Nuculoidea  lens  is 
ranked  first  in  one  sample,  second  in  twelve,  and  third  in  four.  Janeia  silurica  is  ranked  second  in 
five  samples  and  third  in  twelve.  Palaeostraba  baltica  is  ranked  fourth  in  eleven  samples  and  fifth 
in  one.  Caesariella  lindensis  is  ranked  fourth  in  three  samples  and  fifth  in  three. 

The  rates  of  occurrence  of  the  three  most  abundant  species  suggest  co-existence  at  different  tiers. 
Seven  samples  contain  N.  lens  and  J.  silurica  in  fairly  equal  numbers  and  in  all  the  remaining 
samples  but  one  (G79-3),  the  difference  in  occurrence  is  about  14%.  This  strengthens  the 
assumption  that  the  various  species  co-existed  but  at  different  tiers  with  J.  silurica  being  the  deepest, 
in  a similar  manner  to  the  Nucula  proximo  - Solemya  velum  relationship.  In  the  latter  Nucula 
proximo  is  attracted  to  the  burrow  openings  of  Solemya  velum , representing  a positive  association 
(Levinton  1977,  p.  208,  fig.  13). 

N.  lens  and  J.  silurica  also  show  a significantly  higher  rate  of  articulated  valves  (33-8%  and 
3T0%,  respectively)  than  N.  gotlandica  (17-9%),  indicating  a deeper  life-position  of  the  two  first 
mentioned.  The  higher  rate  of  articulated  valves  of  N.  lens , suggested  to  have  lived  at  a shallower 
depth  than  J.  silurica  and  accordingly  exposed  to  more  bioturbation,  may  be  explained  by  its 
taxodont  dentition  resisting  shearing  stresses  better  than  the  edentulous  hinge  of  J.  silurica. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


225 


Samples  0 
G 7 9- 1 15 


50 


100% 


G78-90 

G78-  1 

G77-29 

G79-78 

G78-2 

G78-84 

G79-3 

G 7 8-  1 2 

G78-99 

G78-28 

G79-82 

G78-95 

G79-83 

G78-8 

G78-92 

G79-79 


L2. 


1 1 

. . . 


50 


Absolute 
numbers 
of  specimens 

1 44 


1 59 


170 


1 36 


202 


129 


34 


646 


220 

274 

84 

60 

92 


N.  gotlandica  N.  lens 


J.  silurica 


P-  baltica  C.  lindensis 


text-fig.  4.  Percentage  frequencies  of  the  protobranchs  of  Mollbos. 


The  siphonates  Palaeostraba  baltica  and  C.  lindensis  are  greatly  outnumbered  and  together  make 
at  most  7-6%  of  the  deposit  feeders  of  this  bivalve  community.  P.  baltica  occurs  in  twelve  samples 
while  C.  lindensis  appears  in  six.  In  six  of  the  eight  samples  in  which  N.  gotlandica  dominates  over 
N.  lens  and  J.  silurica  taken  together.  P.  baltica  and  C.  lindensis  are  absent.  On  the  other  hand,  in 
eight  of  the  nine  samples  where  N.  lens  and  J.  silurica  together  dominate  N.  gotlandica , either  P. 
baltica  or  C.  lindensis  or  both  are  present.  Thus,  P.  baltica  and  C.  lindensis  appear  to  have  co-existed 
with  N.  lens  and  J.  silurica  and  probably  inhabited  feeding  levels  different  from  them,  i.e.  they 
occupied  the  shallowest  level,  in  which  C.  lindensis  lived  just  beneath  the  sediment/water  interface. 


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PALAEONTOLOGY,  VOLUME  34 


Thus  when  N.  gotlandica  was  abundant,  the  two  siphonate  deposit  feeders  were  totally  crowded  out, 
or  almost  so.  Their  feeding  activity  was  probably  disturbed  by  the  intense  bioturbation  of  N. 
gotlandica  near  the  sediment  surface. 


MODE  OF  LIFE  OF  1LIONIA  PRISCA  FROM  GROGARNSHUVUD 

The  material  from  Grogarnshuvud  1,  which  constitutes  the  second  example,  consists  of  field 
observations  of  151  in  situ  specimens  from  three  separate  beds  and  additional  specimens  from  other 
beds.  All  specimens  are  preserved  in  calcium  carbonate. 

Evolutionary  aspects 

The  Lucinacea,  constituting  an  ecologic  group  of  infaunal  mucus  feeders,  hold  a unique  position  in 
bivalve  evolution  in  being  the  first  known  suspension  feeders  to  inhabit  a deep  life  position.  They 
seem  to  be  unrelated  to  ‘normal’  siphonate  suspension  feeders  from  which  they  differ  through  their 
unusual  posterior  siphon,  their  unique  anterior  inhalant  mucus  tube,  and  their  anterior-to-posterior 
flow  of  water  through  the  mantle  cavity  (Allen  1958),  and  in  living  in  symbiosis  with  bacteria 
(Dando  et  al.  1986;  Reid  and  Brand  1986). 

The  earliest  representatives  of  Lucinacea  appeared  in  the  Silurian,  much  earlier  than  the  first 
appearance  of  more  typical  siphonate  infaunal  bivalves  of  the  Carboniferous.  True  siphonate 
suspension  feeders,  virtually  absent  in  the  Palaeozoic,  underwent  their  extensive  radiation  first  in  the 
Mesozoic  era  (McAlester  1966;  Stanley  1968). 

Functional  morphology 

A number  of  characters  of  extant  Lucinacea  are  unique  among  bivalves  and  some  of  them  may  be 
recognized  in  Ilionia  prisca  [Hisinger,  1837;  original  combination  Tellina  ( Lucinal ) prisca ] as  well 
(Text-figs  5 and  6). 

One  of  the  most  striking  external  features  is  the  posterior  sulcus  (Text-fig.  5c)  which  in  Recent 
species  normally  indicates  the  presence  of  siphons  and  also  follows  the  line  of  attachment  of  the  gills 
(Allen  1958,  p.  427;  cf.  muscle  scars  in  corresponding  position  of  Ilionia  prisca  in  Text-fig.  5b). 

Another  characteristic  is  the  hypertrophied,  linguiform  anterior  adductor  muscle  (often 
conspicuously  contrasting  in  specimens  of  Ilionia  prisca , see  Text-fig.  5a,  b),  the  surface  epithelium 
of  which  is  ciliated  and  which  sorts  the  food  particles  entering  by  the  anterior  inhalant  tube. 

A third  characteristic  of  the  Lucinacea  is  the  channel  (passage  area  in  Ilionia  prisca , Text-figs  5b 
and  6)  between  the  anterior  adductor  muscle  and  the  pallial  attachment  of  the  mantle  (pallial  line) 
in  which  the  vermiform  part  of  the  foot  can  operate  (Allen  1958,  p.  435). 

The  foot  of  Lucinacea  is  highly  specialized  and  in  some  species  it  can  extend  to  more  than  ten 
times  the  length  of  the  shell.  The  mucus  inhalant  tube  is  constructed  in  the  sediment  by  the  anterior, 
vermiform  part  of  the  foot.  In  some  species  the  posterior  part  of  the  foot  or  heel  may  be  protruded 
and  burrowing  performed  (Allen  1958,  p.  448). 

Recent  lucinaceans  lack  a posterior  inhalant  siphon.  Instead  they  have  evolved  the  ability  to  form 
an  anterior  inhalant  mucus  tube  in  the  sediment.  The  posteriorly  situated  exhalant  siphon,  if 
present,  is  unique  since  no  siphonal  retractor  muscles  of  normal  type  (cf.  Stanley  1968),  are  present 
and  therefore  no  pallial  line  is  formed  in  the  shell  (Allen  1958,  p.  430). 

In  soft  part  morphology  the  Lucinacea  are  characterized  by  a thickened  ctenidium  consisting  of 
single  demibranchs,  gill-mantle  fusion,  the  existence  of  mantle  gills  and  a type  V stomach  (Purcheon 
1958).  Finally,  representatives  of  the  two  families  Lucinidae  and  Thysiridae  live  in  symbiosis  with 
sulphur-oxidizing  bacteria  (Reid  and  Brand  1986). 

Compared  to  extant  Lucinacea  the  shell  of  Ilionia  prisca  is  more  elongate  in  antero-posterior 
direction,  due  to  its  extremely  elongate  anterior  adductor  muscle.  This  could  also  indicate  that 
Ilionia  prisca  was  better  suited  for  rapid  burrowing.  The  impressions  of  the  anterior  adductor 
muscle  scar  are  larger  and  consequently  the  contractile  power  of  this  muscle  is  likely  to  have  been 
considerably  greater.  The  conspicuously  expanded  anterior  adductor  muscle  scar  also  must  have 


LILJEDAH  L:  BIVALVE  FEEDING  STRATEGIES 


227 


text-fig.  5.  Ilionia  prisca.  a,  internal  view  of  a single  right  valve,  note  conspicuous  anterior  adductor  muscle 
scar,  RMMO  17790,  Ostergarn,  Ludlovian  Hemse  Beds,  x 1-2.  b,  lateral  view  of  internal  mould  of  articulated 
specimen,  anterior  to  the  left,  note  gill  attachment  muscle  scars  (arrowed)  and  radial  muscle  scars  of  the  mantle 
edge,  note  also  space  between  the  anterior  adductor  muscle  scar  and  pallial  line,  RMMO  149879,  Ostergarn, 
Ludlovian  Hemse  Beds,  x 1-2.  c,  external  lateral  view  of  a single  left  valve,  RMMO  158171,  Histilles, 

Ludlovian  Hemse  Beds,  x 1.0. 


reduced  the  space  available  for  the  gills,  which  were  comparatively  smaller  than  those  of  its  living 
relatives.  This  could  have  resulted  in  a less  efficient  sorting  ability  of  the  gills  as  compared  to  its 
Recent  relatives. 

On  the  other  hand,  if  the  greatly  extended  ventral  part  of  the  anterior  adductor  muscle  (the 
muscle  scar  being  considerably  larger  than  in  modern  lucinaceans)  acted  as  a sorting  area  for 
inhaled  particles,  this  could  have  compensated  for  smaller  sized  gills. 

Ilionia  prisca  is  integripalliate,  as  are  Recent  lucinaceans,  but  is  believed  to  have  had  a posterior 
exhalant  siphon,  as  indicated  by  the  conspicuous  external  posterior  diagonal  sulcus  (cf.  Allen  1958, 
p.  449). 

In  some  specimens  the  ventral  margin  is  undulating.  This  feature,  also  present  in  for  example 
Grammysia , in  combination  with  the  elongate  shell  form  may  have  helped  in  rapid  downward 
burrowing  (see  Bambach  1971;  Marsh  1984). 

The  Silurian  Ilionia  prisca  shows  such  remarkable  conformity  with  living  Lucinacea  that  it  may 


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PALAEONTOLOGY,  VOLUME  34 


safely  be  assumed  that  Ilionia  prisca  had  adopted  the  unusual  lucinacean  life  habit  (see  McAlester 
1965),  a mode  of  life  already  initiated  in  Ordovician  times  by  the  genus  Babinka.  In  addition  to  the 
suspension  feeding  habit,  Ilionia  prisca  possibly  also  housed  sulphur-oxidizing  bacteria  in  its  gills, 
in  analogy  with  its  living  relatives  (cf.  Reid  and  Brand  1986). 

Life  habit 

Extant  Lucinacea  are  uniquely  adapted  for  deeply  burrowing  suspension-feeding  in  environments 
with  a low  oxygen  and  a high  sulphur  content  (Southward  1986).  In  their  gills  they  have 
chemoautotrophic  endosymbiotic  bacteria  (sulphur-oxidizing)  which  act  as  important  nutritional 
providers  for  the  bivalve  (Berg  and  Alatolo  1984;  Spiro  et  al.  1986).  Some  authors  consider  this 
symbiosis  to  be  the  main  feeding  mode  (Reid  and  Brand  1986). 

Besides  the  bacterial  symbiosis  the  lucinaceans  feed  in  the  following  way  (Text-fig.  6a).  In  a 
deeply  buried  position,  nutrient-laden  water  is  drawn  into  the  mantle  cavity  through  an  anterior 
mucus-lined  tube  in  the  sediment,  made  by  the  vermiform  part  of  the  foot.  The  water  passes  the 
ciliated  ventral  part  of  the  anterior  adductor  muscle  which  acts  as  a sorting  area  before  the  water 
reaches  the  gills.  The  exhalant  water  with  indigestible  particles  is  expelled  posteriorly  by  rapid 
contraction  of  the  adductor  muscles,  in  some  species  through  a posterior  siphon  to  the  sediment 
surface,  in  others  directly  into  the  sediment  (Allen  1958). 

Based  on  comparative  anatomy  with  its  Recent  descendants  (Allen  1958),  it  is  concluded  that 
Ilionia  prisca  was  a deeply  burrowing,  shallow  subtidal  suspension  feeder  (Text-fig.  6b).  Ilionia 
prisca  lived  in  a soft,  carbonate  mud  of  low  oxygen  and  high  sulphur  content,  bioturbated  to  the 
extent  that  the  original  lamination  is  completely  lost  (Sundquist  1982,  p.  87).  In  equivalent 
sediments  today  the  diversity  of  suspension-feeding  bivalves  is  commonly  low  (Buchanan  1958; 
Rhoads  1970;  Rhoads  and  Yonge  1970).  Indeed,  species  diversity  is  low  at  Grogarnshuvud  1 (see 
Sundquist  1982,  p.  88),  including  only  three  additional  bivalve  species,  an  undescribed,  epi-byssate 
suspension  feeder,  a protobranch  nuculoid  and  the  protobranch  solemyoid  Janeia  silurica.  The 
suspension  feeder  (found  as  disarticulated  valves  only)  was  most  probably  exotic  and  transported 
into  the  present  bivalve  community  together  with  empty  orthocone  nautiloid  shells  during 
ephemeral  events  (see  Rhythmic  trapping,  below).  Alternatively,  if  it  belonged  to  the  present 
bivalve  community,  it  may  possibly  have  occupied  a high  level,  epi-byssate  position. 

The  presence  of  protobranchs  indicates  a high  organic  content  in  the  original  substrate.  Extant 
Lucinacea  generally  live  in  environments  where  the  food  supply  is  so  low  that  all  available  food 
particles  must  be  accepted  (Allen  1958,  p.  480).  This  is  achieved  by  their  specialized  sorting 
mechanism  with  the  help  of  symbiotic  bacteria.  The  suggestion  of  similar  conditions  at  this  locality 
at  the  time  of  sedimentation  seems  reasonable.  The  assumed  low  oxygen  and  high  sulphur  content 
of  the  substrate  at  Grogarnshuvud  1 might  explain  the  low  bivalve  diversity  with  only  two 
additional  infaunal  bivalve  species,  the  deepest  one,  Janeia  silurica , also  assumed  to  have  had 
symbiotic  sulphur  reducing  bacteria  (by  analogy  with  its  living  relatives).  Ilionia  prisca  most 
probably  had  a specially  developed  sorting  mechanism  as  well  as  a strong  adductor  muscle,  capable 
of  powerful  retraction  and  closure  of  the  valves  for  efficiently  discharging  indigestible  particles 
posteriorly.  Its  deep  life  position  suggests  that  it  lived  in  the  oxygen-poor,  sulphur-rich  zone  of  the 
sediment,  which  strengthens  the  idea  of  a symbiosis  with  anaerobic  bacteria.  Other  lucinid-solemyid 
associations  have  also  been  connected  with  fine-grained  and  poor-food  habitats,  e.g.  the  Cenozoic 
Thyasira-Lucinoma-Solemya  association  (Hickman,  1984). 

Feeding  capacity  is  one  of  the  most  important  features  upon  which  selection  pressure  acts  in 
animal  species  (Stanley  1970,  p.  79),  and  it  appears  that  the  unique  feeding  strategy  of  Ilionia  prisca 
(a  deep  life  position  with  an  inferred  anterior  inhalant  tube  and  a posterior  exhalant  system  in 
combination  with  symbiosis  with  sulphur-oxidizing  bacteria),  seems  to  have  been  an  optimal 
adaptation  to  an  environment  hostile  to  all  other  infaunal  suspension  feeding  bivalves. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


229 


text-fig.  6.  a,  life  position  of  Recent  lucinacean  bivalves  (modified  after  Allen  1958 ; McAlester  1965);  the  foot, 
the  sites  of  the  adductor  muscles  (stippled)  and  the  posterior  exhalant  siphon  are  shown,  b,  suggested  life 
position  and  reconstruction  of  the  foot  and  posterior  exhalant  siphon  of  Ilionia  prisca  (muscular  impressions 
stippled);  water  is  inhaled  through  a mucus  lined  tube;  arrows  indicate  direction  of  water  flow. 

Preferred  orientation 

Grogarnshuvud  1 includes  a series  of  beds  of  interlayered  fine  grained  limestones  and  calcareous 
shales  belonging  to  the  Hemse  Beds,  units  c and  d (for  detailed  descriptions  see  Sundquist  1982). 

At  several  horizons  a large  number  of  in  situ  specimens  of  IHonia  prisca  can  be  observed 
contrasting  conspicuously  with  the  recently  eroded  bedding  planes.  In  four  of  the  beds  abounding 
in  Ilionia  prisca  (Nos  1,  2,  10,  11)  the  orientation  of  the  bivalves  was  measured.  In  three  of  these 


230 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  7.  Rose  diagram  of  direction  of  anterior  end  showing  orientation  of  anteroposterior  axis  of  in  situ 
specimens  of  Ilionia  prisca  and  of  orthocone  nautiloid  shells  on  bedding  planes  at  Grogarnshuvud  1 . n = 

numbers  of  specimens. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


231 


beds  (Nos  1,2,  11)  and  an  additional  bed  (No.  3 with  less  abundant  Ilionia  prisca)  the  orientation 
of  orthoconic  nautiloid  shells  was  recorded.  The  results  are  presented  in  Text-figure  7. 

Sundquist  (1982,  p.  85,  fig.  4)  made  a similar  study  of  nautiloid  shell  orientation  in  this  locality. 
Bed  No.  1 probably  corresponds  to  Sundquist's  No.  4,  bed  No.  2 to  his  No.  3,  and  bed  No.  3 to 
his  No.  2.  Bed  No.  10  lacks  nautiloid  shells  while  in  bed  1 1 there  are  only  eight  recorded  specimens. 

In  addition  to  the  bivalve  specimens  in  situ  on  the  bedding  planes  a number  of  in  situ  specimens 
were  found  well  within  the  limestone  beds. 

In  principle  the  bivalves  exhibit  a quadro-polar,  preferred  in  situ  orientation  with  their  anterior 
end  pointed  in  approximately  NW,  SE,  ENE,  WSW  directions,  which  seem  to  be  consistent 
throughout  the  beds  at  this  locality  (Text-fig.  7).  In  bed  No.  1 there  is  a dominant  direction  to  the 
E,  in  bed  No.  2 a dominant  direction  to  the  SE,  whereas  bed  No.  1 1 lacks  a dominant  anterior 
direction  to  the  SE. 

Discussion.  Some  bivalves  have  evolved  the  behaviourial  strategy  of  orienting  themselves  in  a 
direction  favourable  for  feeding.  A few  commensal  species  of  Erycinacea,  for  example,  orient 
themselves  with  their  anterior  end  (where  the  inhalant  siphon  is  situated)  towards  their  host,  due 
to  chemokinetic  response  (Morton  1962).  Other  species  of  the  same  family  are  able  to  orient 
themselves  with  their  anterior  end  to  stimuli  of  light,  gravity  and  lateral  contact  (Morton  1960). 
Some  burrowing  bivalves  orient  themselves  preferentially  with  their  posterior  siphon  against  the 
prevailing  current  direction.  For  example,  the  alignment  of  Anadara  trapezia  is  correlated  with  the 
direction  and  strength  of  tidal  or  wind-driven  water  currents  (O’Gower  and  Nicol  1971).  It  is 
assumed  that  correct  orientation  of  this  bivalve  would  assist  respiration,  feeding  and  sanitation,  and 
would  possibly  also  lessen  the  chances  of  accidental  dislodgement  (O'Gower  and  Nicol  1971, 
p.  277).  Some  fresh-water  bivalves  also  show  preferred  orientation  in  relation  to  water  currents 
(J.  Khz,  pers.  comm.  1988). 

As  far  as  the  orientation  of  Ilionia  prisca  is  concerned,  it  may  be  related  directly  to  the  alignment 
of  the  orthocone  nautiloid  shells  on  the  same  bedding  planes  or  to  a factor  which  affected  both  the 
bivalves  and  the  empty  cephalopod  shells.  Sundquist  (1982)  concluded  that  the  bipolar  apex 
orientation  of  the  nautiloid  shells  indicates  a preferred  orientation  caused  by  wave  action.  The 
orientation  pattern  does  not,  however,  form  two  completely  opposing  maxima,  and  is  interpreted 
as  the  result  of  interacting  forces  of  waves  and  wave  currents.  The  wave  progression  is  suggested 
to  have  been  from  ESE  (Sundquist  1982,  p.  85). 

The  orientation  of  the  nautiloid  shells  in  this  paper  (Text-fig.  7),  agrees  with  those  in  Sundquist’s 
study,  thus  strengthens  the  assumption  of  a fairly  constant  main  wave  progression  from  the  ESE 
in  this  area  at  the  time  of  sedimentation. 

Assuming  that  the  different  beds  at  this  locality  were  deposited  under  fairly  constant  conditions 
(Sundquist  1982,  p.  86),  the  stable  uniform  orientation  of  the  nautiloid  shells  may  be  taken  as  a 
criterion  of  a constant  shore  line  direction,  parallel  to  the  anterior-posterior  axis  of  the  shells. 
Although  caution  should  be  taken  in  interpretations  of  palaeogeography  based  on  locally  restricted 
material,  the  shore  line  at  this  locality,  as  indicated  by  the  elongated  shells  of  nautiloids  and 
gastropods,  at  the  time  of  sedimentation  seems  to  have  been  aligned  roughly  NNE-SSW.  This 
direction  agrees  fairly  well  with  earlier  reconstructions  of  shore  lines  and  palaeobathymetry  on 
Gotland  (Hadding  1958,  Manten  1971,  Laufeld  1974,  Eriksson  and  Laufeld  1978,  Bergman  1979, 
Sundquist  1982). 

The  orientation  of  the  length  axis  of  the  bivalves  of  each  individual  bed  at  this  locality  is  fairly 
constant,  which  is  also  the  case  with  the  nautiloid  shells,  indicating  a wave  progression  direction 
from  the  ESE.  Thus,  it  seems  as  though  Ilionia  prisca  oriented  itself  with  its  anterior-posterior  axis 
oblique  to  the  prevailing  wave  direction,  in  which  the  suspended  (food)  particles  travel.  If  so,  its 
anterior  inhalant  mucus  tube  was  facing  the  net  transport  of  food  particles  (Text-fig.  8b;  cf.  similar 
life  position  of  Thyasira  and  Lucinoma  with  the  opening  of  their  anterior  mucus  tube  facing  the 
current  at  the  sediment/water  interface,  in  Hickman  1984,  fig.  9).  Probably  this  orientation  was 
more  advantageous  than  if  the  bivalves  were  aligned  in  the  same  direction  as  water  movement  (Text- 


232 


PALAEONTOLOGY,  VOLUME  34 


c=> 

oscillating 
water  movement 


text-fig.  8.  Orientation  of  anteroposterior  axis 
(broken  lines)  of  llionia  prisca  in  relation  to  water 
movement.  Anterior  inhalant  tube  (open  circle)  and 
posterior  exhalant  siphon  (filled  circle),  thin  arrows 
showing  direction  of  waste  products,  a,  hypothetical 
in  line-orientation,  b,  observed  oblique  orientation. 


A — * 


♦ — -o 


B 


fig.  8a).  In  the  latter  case,  with  an  oscillating  wave  movement,  the  chances  of  inhaling  its  own  waste 
products  are  greater  than  in  case  of  oblique  orientation. 

Rhythmic  trapping 

A number  of  the  limestone  beds  at  Grogarnshuvud  1 abound  in  llionia  prisca  while  others  contain 
few  or  no  specimens.  Each  of  the  beds  discussed  is  intercalated  with  calcareous  shales.  The  thickness 
of  the  limestone  beds  ranges  from  70  to  130  mm.  The  shales  are  usually  10  mm  thick  but  can  in 
places  reach  60  mm  (see  also  Sundquist  1982). 

It  is  suggested  that  each  limestone  bed  represents  one  life  association  of  llionia  prisca , although 
there  is  a conspicuous  lack  of  juvenile  specimens  (Liljedahl,  in  prep.). 

Sundquist  (1982,  pp.  87-89)  assumes  that  the  calcareous  shale  beds  represents  the  final  stage  of 
a previous  ephemeral  incident,  such  as  a storm,  etc.  The  shales  were  deposited  rhythmically  and 
possibly  some  of  them  represent  volcanic  ash-falls  rich  in  silica,  indicated  by  the  presence  of  silicified 
fossils.  On  such  occasions  a large  number  of  floating  nautiloid  shells  were  stranded  and  oriented 
parallel  to  the  shore  due  to  storm-wave  action.  The  water  was  heavily  loaded  with  suspended 
particles,  which  eventually  came  to  rest,  resulting  in  a deposit  considerably  thicker  than  the  present 
thin  shale  beds.  The  fouling  of  the  water  and/or  sedimentation  of  the  fine  grained  material  most 
probably  was  catastrophic  for  the  bivalves  and  the  infaunal  species  were  forced  to  escape. 

However,  when  overburden  stress  reaches  a critically  high  value,  burrowing  infaunal  organisms 
can  not  escape  burial.  Experiments  on  living  polychaete/bivalve  communities  show  that  this  value 
(40  Kpa)  corresponds  to  a burial  depth  of  c.  28  cm  (Nicols  et  al.  1978).  Specimens  of  llionia  prisca 
are  found  down  to  a depth  of  10  cm  or  more  in  the  sediment  and  with  an  overburden  of  a thick  layer 
of  clay  (now  considerably  compacted).  This  limit  could  have  been  reached  in  the  present  community 
at  Grogarnshuvud  1 and  the  infaunal  bivalves  fatally  trapped.  It  seems  as  if  no  reworkers,  including 
protobranch  bivalves,  gastropods,  annelid  worms  etc.  survived,  since  llionia  prisca  was  preserved 
undisturbed  in  ‘life’  position. 

As  stated,  specimens  of  llionia  prisca  have  been  found  at  different  depths  in  the  beds  and  even 
at  the  sediment  surface  (all  orientation-measured  specimens).  A number  of  individuals  are  inclined, 
with  their  antero-posterior  axis  dipping  at  an  angle  of  10-15°  to  the  bedding  plane  (Text-fig.  9).  This 
suggests  that  these  individuals  were  killed  during  the  rocking  movement  of  burrowing,  perhaps 
while  attempting  to  escape.  According  to  Stanley  (1972)  and  Nicols  et  al.  (1978),  in  a series  of 
experiments,  individual  burrowing  ability  of  each  bivalve  species  resulted  in  differences  in  escape 
efficiency.  Although  no  escape  structures  have  been  found  in  the  different  beds  at  Grogarnshuvud, 
the  slurry-like  nature  of  the  sediment  may  account  for  their  absence. 


LILJEDAHL:  BIVALVE  FEEDING  STRATEGIES 


233 


text-fig.  9.  In  situ  specimens  of  Ilionia  prisca  on  eroded  bedding  surfaces,  Grogarnshuvud  1,  Ludlovian  Hemse 
Beds.  A,  articulated  specimen  preserved  as  internal  mould  of  surrounding  sediment,  x 0.6.  b,  articulated 
specimen  preserved  as  druse  filled  internal  mould,  x 0-7. 


The  specimens  found  on  the  bedding  planes  either:  (1)  succeeded  in  escaping  burial;  their  gills 
were,  however,  eventually  clogged  due  to  the  large  amount  of  fine  grained  suspension  in  the  very 
turbid  water;  or  (2)  they  were  killed  in  ‘life’  position,  or  rather  ‘death’  position  after  having 
burrowed  themselves  downwards  in  the  sediment  and  later  isolated  by  erosion  caused  by  the 
ephemeral  violent  event.  The  presence  of  some  specimens,  preserved  as  drusy  filled  cavities  (Text- 
fig.  9b),  supports  this  latter  assumption.  They  indicate  extremely  rapid  burial  and  enough 
compaction  forces  to  prevent  the  ligament  to  open  the  valves  after  soft  part  corruption. 

The  absence  of  Ilionia  prisca  from  some  of  the  beds  may  result  from  the  sedimentation  of  the  fine 
grained  material  not  being  rapid  enough  for  catastrophic  burial.  Alternatively  the  high  turbidity 
event  may  have  been  too  short  for  the  bivalves  to  be  suffocated.  In  either  case  the  bivalves  might 
have  been  able  to  escape  and  survive.  It  is  also  possible  that  the  bivalves  had  not  yet  colonized  the 
area  after  the  previous  catastrophic  event. 

It  seems  as  if  only  one  or  a few  age  classes  colonized  the  area  after  each  previous  mud 
sedimentation  event.  Presumably  either  these  individuals  were  killed  during  the  following 
catastrophic  incident  before  they  were  able  to  reproduce,  or  the  environment  was  simply 
unfavourable  for  their  young  offspring  (see  Rhoads  and  Young  1970). 


Repository.  Specimens  with  their  numbers  prefixed  RMMO  are  deposited  in  the  type  collection  of  the  Swedish 
Museum  of  Natural  History,  Box  50007,  S-104  05  Stockholm,  Sweden,  those  prefixed  SGU  TYPE  are 
deposited  in  the  type  collection  of  the  Geological  Survey  of  Sweden,  Box  670,  S-751  28  Uppsala,  Sweden,  and 
those  prefixed  LO  in  the  type  collection  of  the  Geological  Institute,  Lund  University,  Solvegatan  13,  S-223  62 
Lund,  Sweden. 


Acknowledgements.  The  present  paper  is  a longer  version  of  a talk  given  at  the  Murchison  Symposium  on 
2 April  1989  at  Keele  University.  Sincere  thanks  are  due  to  Sven  Laufeld,  Jin'  Kri'z,  Anita  Lofgren  and  Euan 
Clarkson  for  valuable  comments  and  improvements  of  the  manuscript  and  also  to  Euan  Clarkson  for  linguistic 
help.  Lennart  Jeppsson  kindly  gave  access  to  huge  samples  from  Mollbos  1.  A travel  grant  from 
Naturvetenskapliga  Forskningsradet  is  gratefully  acknowledged. 


234 


PALAEONTOLOGY,  VOLUME  34 


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Typescript  received  14  November  1989 
Revised  typescript  received  19  March  1990 


LOUIS  LILJEDAHL 

Department  of  Historical  Geology  and  Palaeontology 
Solvegatan  13 
S-233  62  Lund,  Sweden 


LIZARD  EGG  SHELLS  FROM  THE  LOWER 
CRETACEOUS  OF  CUENCA  PROVINCE,  SPAIN 

by  ROLF  KOHRING 


Abstract.  The  Lower  Cretaceous  vertebrate-bearing  coaly  marls  and  limestones  of  Una  (Province  of  Cuenca, 
Spain)  have  yielded  fragmentary  reptilian  egg  shells.  The  shell  is  of  gekkonid  microstructure  type,  and  thus  they 
can  be  confidently  assigned  to  the  lizards.  These  fragments  represent  the  oldest  known  gekko-like  egg  shells. 

Fossil  egg  shells  have  been  reported  nearly  worldwide,  especially  from  Upper  Cretaceous  and 
Tertiary  deposits,  and  they  have  been  assigned,  according  to  their  microstructure  and 
biomineralization,  to  turtles,  crocodiles,  dinosaurs,  and  birds  (reviewed  by  Hirsch  and  Packard 

1987) .  Fossilized  egg  shells  of  snakes  and  lizards,  however,  are  only  rarely  described,  owing  to  their 
largely  non-mineralized  composition ; nearly  all  squamates  produce  eggs  with  soft  shells  consisting 
of  interlacing  protein  fibrils  and  some  calcareous  matter,  probably  homologous  to  the  membrana 
testacea  of  avian  eggs  (Schleich  and  Kastle  1988).  Only  the  recent  gekkonids  (Lacertilia)  develop 
calcified  (and  thus  fossilizable)  rigid  egg  shells,  characterized  by  a continuous  layer,  composed  of 
tightly  abutted  jagged  columns,  and  surface  nodes.  The  thickness  of  both  fossil  and  recent  gekkonid 
egg  shells  ranges  from  35  to  280  /mi  (Schleich  and  Kastle  1988). 

Fossil  gekko-like  egg  shells  are  reported  from  the  Lower  Miocene  of  Kenya  (Hirsch  and  Harris 
1989),  the  Oligocene  of  the  Mainz  Basin  (Schleich  and  Kastle  1988),  the  Lower  Eocene  of  Wyoming 
(Hirsch  and  Packard  1987),  the  Cretaceous/Tertiary-boundary  of  Peru  (Hirsch  in  Mourier  et  aL 

1988) ,  the  Upper  Cretaceous  of  both  Montana  (Hirsch  and  Quinn,  in  press)  and  India  (Sahni  et  al. 
1984),  and  the  Lower  Cretaceous  of  Mongolia  (Alifanov  1989).  One  genus  (Ilerdaesaurus  sp.)  of  this 
material  is  under  study  by  A.  Richter  (Berlin).  According  to  Hoffstetter  (1964)  gekkonids  are  known 
since  the  Upper  Jurassic.  The  lizards  of  Una  are  not  yet  described  (Krebs,  pers.  comm.) 


LOCALITY  AND  STRATIGRAPHY 

The  coal-bearing  marls  and  limestones  of  Una  (province  of  Cuenca,  Spain)  have  yielded  tetrapods, 
especially  frogs  (Fey  1988),  turtles  and  lizards  (Krebs,  pers.  comm.),  crocodiles  (Brinkmann  1989), 
and  early  mammals  (Henkel  and  Krebs  1969).  They  have  been  dated  as  Upper  Barremian  on  the 
basis  of  palynomorphs  (Mohr  1989),  ostracodes,  and  charophytes  (Schudack  1989).  The 
palaeoenvironment  of  Una  is  postulated  to  have  been  lacustrine,  with  marshy,  deltaic  deposits 
(Gierlowski-Kordesch  and  Janofske  1990).  The  egg  shells  described  here  are  well  preserved;  only 
their  margins  are  partially  pyritized,  as  is  typical  also  for  the  gastropods,  ostracodes,  and 
charophytes  of  Una. 


THE  MATERIAL 


Description 

In  all,  eight  tiny,  dark  brown  coloured  shell  fragments  (5  x 10  mm),  embedded  in  the  coaly  sediment,  have  been 
studied  in  thin  sections  and  by  scanning  electron  microscopy  (SEM,  Cambridge  Stereoscan  360).  In  thin 
section,  the  egg  shells  display  a continuous  layer  with  hardly  visible  fine,  closely  spaced  growth-stage  lines  and 
a light  coloured  secondary  layer  in  the  outer  part,  which  is  obviously  a diagenetic  structure  (Hirsch,  pers. 


IPalaeontology,  Vol  34,  Part  1,  1991,  pp.  237-240,  1 pl.| 


© The  Palaeontological  Association 


238 


PALAEONTOLOGY,  VOLUME  34 


comm.)  (PL  1,  fig.  5).  It  is  never  pyritized  in  any  of  the  specimens.  In  XPL  an  extinction  pattern  with  cone- 
shaped  wedges  in  the  upper  part  of  the  primary  layer  and  partially  in  the  secondary  layer  is  visible. 

In  SEM  studies,  some  further  morphological  features  can  be  observed.  The  shell  consists  of  a nearly 
complete  homogenous  calcitic  layer  without  recognizable  shell  units  (PL  1,  figs  2 and  6),  and  therefore  is  very 
similar  to  the  recent  gekko  Ptyodactylus  (Schleich  and  Kastle  1988).  In  its  upper  part,  the  20  /rm  thick 
secondary  layer  with  horizontal  crystallites  is  visible  (PI.  1,  fig.  4).  This  characteristic  structure  has  been 
mentioned  also  from  Upper  Cretaceous  gekko-like  egg  shells  of  Montana  (Hirsch  and  Quinn,  in  press)  and 
from  hadrosaurian  egg  shells  (Hirsch  and  Packard  1987).  The  surface  is  covered  with  a thin  3 /an  mineralized 
layer,  as  is  typical  for  nearly  all  recent  gekkos  (Schleich  & Kastle  1988).  However,  this  layer  has  never  been 
reported  from  fossil  lizard  eggs.  The  shell  thickness,  including  surface  nodes,  is  170-180  //m.  The  diameter  of 
these  nodes  is  about  100  /nn  (PI.  1,  fig.  1). 


Discussion 

Other  distinctive  reptilian  egg  shell  microstructures,  such  as  pores,  pore  openings,  and  basal 
aragonitic  mammallae  could  not  be  found.  Probably  the  rigid  gekkonid  egg  shell  is  not  homologous 
to  those  of  other  reptiles  or  birds. 

The  remarkable  structural  similarities  to  modern  gekkonid  egg  shells  allow  the  assignment  of  the 
Una  material  to  the  lizards.  These  late  Barremian  fragments  are  the  oldest  known  certain  lizard  egg 
shells.  Due  to  the  poor  knowledge  of  the  problematic  diagenetic  pattern  of  egg  shells  an 
identification  of  the  very  thin  outer  layer  as  a mineralized  organic  cover  seems  hitherto  impossible. 
The  fragmentation  of  the  shells  suggests  substantial  transport.  The  primary  shapes  and  sizes  of 
the  eggs  cannot  be  reconstructed. 

A single  thin-shelled  (about  50  //m)  fragment  is  known  from  the  Upper  Jurassic  (Kimmeridgian) 
coaly  marls  and  limestones  of  Guimarota  (Central  Portugal),  where  turtle  egg  shells  have  been 
described  (Kohring  1990).  It  is  similar  in  microstructure  to  recent  gekkonid  egg  shells,  but  its  real 
taxonomic  position  is  uncertain  (PI.  1,  fig.  8). 


Acknowledgements.  I thank  Professor  B.  Krebs  (Berlin)  for  material  and  information  on  Una,  and  Dr  K.  F. 
Hirsch  (Denver)  for  useful  remarks.  The  field  work  was  supported  from  the  Deutsche  Forschungsgemeinschaft 
(DFG).  My  sincere  thanks  go  to  Miss  H.  Bosbach  (Berlin)  for  reading  the  typescript  critically,  to  Dr  J.  Reitner 
(Berlin)  for  providing  me  with  recent  lizard  egg  shells,  and  to  Dr  D.  Martill  (Milton  Keynes)  and  Dr  M.  J. 
Benton  (Bristol)  for  useful  comments. 


REFERENCES 

alifanov,  v.  r.  1989.  The  oldest  gecko  (Lacertilia,  Gekkonidae)  from  the  Lower  Cretaceous  of  Mongolia. 
Paleontological  Journal  23.  128-131. 

brinkmann,  w.  1989.  Vorlaufige  Mitteilung  fiber  die  Krokodilier-Faunen  aus  dem  Ober-Jura  (Kimmeridgium) 
der  Kohlegrube  Guimarota,  bei  Leiria  (Portugal)  und  der  Unter-Kreide  (Barremium)  von  Una  (Provinz 
Cuenca,  Spanien).  Documenta  naturae  56,  1-26. 


EXPLANATION  OF  PLATE  1 

Figs  1-6.  Lizard  egg  shell  fragments  from  the  Lower  Cretaceous  of  Una.  1,  outer  surface  with  nodes,  x 50.  2, 
lateral  view  with  homogenous  calcitic  layer,  secondary  layer,  outside  is  up,  x 100.  3,  lateral  view,  note 
secondary  layer,  x 200.  4,  Secondary  layer,  x 400.  5,  lateral  view  in  thin  section  in  ordinary  light,  outside 
with  a secondary  layer  is  up,  note  pyritized  margins,  x 50.  6,  lateral  view,  x 80. 

Fig.  7.  Recent  gekko  egg  shell,  Tarentola  sp.,  lateral  view  with  nodose  outer  surface,  x 300. 

Fig.  8.  Uncertain  gekko-like  egg  shell  from  the  Upper  Jurassic  of  Guimarota,  lateral  view,  x 300. 
Specimens  are  housed  in  the  Institut  ffir  Palaontologie,  Freie  Universitat  Berlin  under  the  registered  numbers 
Un  Bar  ES  1-8. 


PLATE  1 


KOHRING,  lizard  egg  shells 


240 


PALAEONTOLOGY,  VOLUME  34 


fey,  b.  1988.  Die  Anurenfauna  aus  der  Unterkreide  von  Una  (Ostspanien).  Berliner  geowissenschaftliche 
Abhandlungen  A 103,  1-125. 

gierlowski-kordesch,  E.  and  janofske,  d.  1990.  Paleoenvironmental  reconstruction  of  the  Weald  around  Una 
(Serrania  de  Cuenca,  Cuenca  Province,  Spain).  In  wiedmann,  j.  (ed.).  Cretaceous  of  the  Western  Tethys. 
Proceedings  3rd  International  Cretaceous  Symposium,  Tubingen  1987,  Schweizerbart,  Stuttgart. 
henkel,  s.  and  krebs,  b.  1969.  Zwei  Saugetier-Unterkiefer  aus  der  Unteren  Kreide  von  Una  (Provinz  Cuenca, 
Spanien).  Neues  Jahrbuch  fur  Geologic  und  Palaontologie , Monatshefte,  1969,  449  463. 
hirsch,  k.  f.  and  Harris,  j.  1989.  Fossil  eggs  from  the  Lower  Miocene  Legetet  Formation  of  Koru,  Kenya: 
snail  or  lizard?  Historical  Biology , 3,  61-78. 

— and  Packard,  m.  j.  1987.  Review  of  fossil  eggs  and  their  shell  structure.  Scanning  Microscopy,  1,  383-400. 

— and  quinn,  b.  In  press.  Eggs  and  eggshell  fragments  from  the  Upper  Cretaceous  Two  Medicine  Formation 
of  Montana.  Journal  of  Vertebrate  Paleontology. 

hoffstetter,  r.  1964.  Les  Sauria  du  Jurassique  superieur  et  specialements  les  Gekkota  de  Baviere  et  de 
Mandchourie.  Senckenbergiana  Biologica,  45,  281-324. 
kohring,  R.  1990.  Upper  Jurassic  chelonian  eggshell  fragments  from  the  Guimarota  Coalmine  (Central 
Portugal).  Journal  of  Vertebrate  Paleontology,  10,  128-130. 
mohr,  b.  1989.  New  palynological  information  on  the  age  and  environment  of  Late  Jurassic  and  Early 
Cretaceous  vertebrate  localities  of  the  Iberian  Peninsula  (eastern  Spain  and  Portugal).  Berliner 
geowissenschaftliche  Abhandlungen  A,  106,  291-301. 

MOURIER,  TH.,  BENGTSON,  P.,  BONHOMME,  M.,  BUGE,  E.,  CAPPETTA,  H.,  CROCHET,  J.-Y.,  FEIST,  M.,  HIRSCH,  K.  F., 
JAILLARD,  E.,  LAUBACHER,  G.,  LEFRANC,  J.  P.,  MOULLADE,  M.,  NOBLET,  C.,  PONS,  D.,  REY,  J.,  SIGE,  B.,  TAMBAREAU, 
y.  and  taquet,  p.  1988.  The  Upper  Cretaceous-Lower  Tertiary  marine  to  continental  transition  in  the  Bagua 
basin,  northern  Peru.  Paleontology,  biostratigraphy,  radiometry,  correlations.  Newsletters  on  Stratigraphy, 
19,  143-177. 

sahni,  a.,  rana,  r.  s.  and  prasad,  G.  v.  R.  1984.  SEM  studies  of  thin  egg  shell  fragments  from  the 
Intertrappeans  (Cretaceous-Tertiary  Transition)  of  Nagpur  and  Asifabad,  peninsular  India.  Journal  of  the 
Paleontological  Society  of  India , 29,  26-33. 

schleich,  h.  h.  and  kastle,  w.  1988.  Reptile  egg-shells.  Gustav  Fischer  Verlag,  Stuttgart,  123  pp. 
schudack,  m.  1989.  Charophytenfloren  aus  den  unterkretazischen  Vertebraten-Fundschichten  bei  Galve  und 
Una  (Ostspanien).  Berliner  geowissenschaftliche  Abhandlungen  A,  106,  409-443. 


Manuscript  received  18  January  1990. 
Revised  manuscript  received  25  April  1990 


R.  KOHRING 

Institut  fur  Palaontologie 
Freie  Universitat  Berlin 


Schwendenerstrasse  8,  1000  Berlin  33,  Germany 


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Palaeontology 

VOLUME  34  • PART  1 


CONTENTS 

Late  Tremadoc  graptolites  from  western  Newfoundland 

S.  H.  WILLIAMS  and  R.  K.  STEVENS  1 

Middle  Triassic  holothurians  from  northern  Spain 

A.  B.  SMITH  and  J.  GALLEMI  49 

A new  upper  Ordovician  bryozoan  fauna  from  the  Slade  and 
Redhill  Beds,  South  Wales 

C.  J.  BUTTLER  77 

Middle  Ordovician  bivalves  from  Spain  and  their  phyletic  and 
palaeogeographic  significance 

C.  BABIN  CUld  J.-C.  GUTIERRBZ-MARCO  109 

Spongiophyton  from  the  late  Lower  Devonian  of  New  Brunswick 
and  Quebec,  Canada 

P.  G.  GENSEL,  W.  G.  CHALONER  and  W.  H.  FORBES  149 

Teuthid  cephalopods  from  the  Upper  Jurassic  of  Antarctica 

p.  DOYLE  169 

A new  scleractinian-like  coral  from  the  Ordovician  of  the  Southern 
Uplands,  Scotland 

C.  T.  SCRUTTON  and  E.  N.  K.  CLARKSON  179 

The  taxonomy  and  shell  characteristics  of  a new  elkaniid 
brachiopod  from  the  Ashgill  of  Sweden 

L.  E.  HOLMER  195 

Cuticular  ultrastructure  of  the  trilobite  Ellipsocephalus  polytomus 
from  the  Middle  Cambrian  of  Oland,  Sweden 

J.  E.  DALINGWATER,  S.  J.  HUTCHINSON,  H.  MUTVEI 

and  D.  J.  siveter  205 

Contrasting  feeding  strategies  in  bivalves  from  the  Silurian  of 
Gotland 

L.  LILJEDAHL  219 

Lizard  egg  shells  from  the  Lower  Cretaceous  of  Cuenca  Province, 

Spain 

R.  KOHRING  237 


Primed  in  Green  Britain  at  ilie  University  Press , Cambridge 


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Cover:  Bolboforma  intermedia  Daniels  and  Spiegler  (Incertae  Sedis,  possibly  a calcified  algal  cyst)  from  Site  552A,  southwest 
margin  of  Rockall  Plateau,  late  Miocene  NN9-10.  x 800.  Bolboforma  was  planktonic  and  cysts  are  found  in  epicontinental 
shelf  sea  deposits,  thus  providing  a useful  biostratigraphic  link  with  oceanic  sequences. 


A SPIDER  AND  OTHER  ARACHNIDS  FROM  THE 
DEVONIAN  OF  NEW  YORK,  AND 
REINTERPRETATIONS  OF  DEVONIAN  ARANEAE 

by  PAUL  A.  SELDEN,  WILLIAM  A.  SHEAR  and  PATRICIA  M.  BONAMO 


Abstract.  The  oldest  known  spider,  from  the  Devonian  (Givetian)  of  Gilboa,  New  York,  is  Attercopus 
fimbriunguis  (Shear,  Selden  and  Rolfe),  parts  of  which  were  originally  described  as  a trigonotarbid,  possibly 
of  the  genus  Gelasinotarbus.  Previous  reports  of  Devonian  spider  fossils,  from  the  Lower  Emsian  of  Alken- 
an-der-Mosel,  Germany,  and  the  Pragian  of  Rhynie,  Scotland,  are  shown  to  be  erroneous  identifications. 
Attercopus  is  placed  as  sister-taxon  to  all  living  spiders,  on  the  basis  of  characters  of  the  spinneret  and  the 
arrangement  of  the  patella-tibia  joint  of  the  walking  legs.  A cladogram  of  the  relationships  of  all  pulmonate 
arachnids  is  presented.  A pulmonate  arachnid  from  Gilboa,  related  to  Araneae  and  Amblypygi,  is  described 
as  Ecchosis  pulchribothrium  Selden  and  Shear,  gen.  et  sp.  nov.,  and  additional  arachnid  material  is  described. 

A devonian  age  for  the  oldest  known  fossil  spider  was  set  by  Hirst  when  he  described 
Palaeocteniza  crassipes  Hirst,  1923,  from  the  Pragian  Rhynie  Chert  of  Aberdeenshire,  Scotland.  The 
description  of  another  fossil  assigned  to  the  Araneae,  Archaeometal  devonica  Stormer,  1976,  from 
the  Emsian  of  Alken-an-der-Mosel,  Germany,  added  more  evidence  for  the  antiquity  of  the  order. 
The  find  of  a spider  spinneret  (Shear,  Palmer  et  al.  1989)  from  the  Givetian  of  Gilboa,  New  York, 
provided  conclusive  evidence  for  the  validity  of  the  Devonian  as  the  earliest  period  in  which  spider 
fossils  are  known  to  occur.  In  this  paper,  results  of  a re-examination  of  the  Rhynie  and  Aiken  spider 
fossils  are  presented:  the  fossils  are  not  spiders,  and  are  reinterpreted  as  a probable  juvenile 
trigonotarbid  and  an  indeterminate  fossil,  respectively.  The  Gilboa  spider  is  placed  in  a new  genus, 
Attercopus , described  here.  The  new  genus  includes  only  the  animal  previously  called  Gelasino- 
tarbus? fimbriunguis  (Shear  et  al.  1987),  which  we  now  regard  as  the  only  known  Devonian  spider, 
and  the  oldest  known  fossil  of  the  Araneae.  In  addition,  podomeres  originally  placed  in  Arachnida 
incertae  sedis  by  Shear  et  al.  (1987)  are  redescribed  here,  with  the  addition  of  new  material,  as 
Ecchosis  pulchribothrium  gen.  et  sp.  nov.,  and  placed  in  Pulmonata  incertae  sedis  (it  may  be  an 
amblypygid),  and  other  arachnid  remains  from  Gilboa  are  described. 


RHYNIE  PALAEOCTENIZA 

In  1923,  Hirst  described  Palaeocteniza  crassipes  as  a spider  from  the  Pragian  Rhynie  Chert  of 
Scotland.  James  Locke  and  W.A.S.  carried  out  a detailed  photographic  study  of  the  specimen 
(British  Museum  (Natural  History)  (BM(NH))  In  24670)  in  1987  and  1988.  The  fossil  is  in  a small 
chip  of  chert  mounted  on  a microscope  slide.  Even  if  the  fossil  were  to  be  removed  from  the  slide, 
no  additional  views  could  be  obtained,  owing  to  the  opacity  of  the  chert  behind  the  specimen.  The 
specimen  itself  is  highly  three-dimensional,  as  are  many  of  the  arthropod  remains  from  Rhynie,  and 
thus  difficult  to  photograph.  Adding  to  the  problems  are  the  cloudiness  of  the  matrix,  opaque 
inclusions,  and  the  very  small  size  of  the  specimen,  about  0-85  mm  long. 

In  addition  to  photographs  of  the  whole  specimen  at  low  magnifications  (Text-fig.  1),  a series  of 
about  thirty-five  optical  sections  was  made  at  higher  magnification,  using  the  very  shallow  depth-of- 
field  characteristic  of  Nomarski  Differential  Interference  Contrast  (NDIC  - see  below.  Methods). 
These  photographs  were  printed  at  a large  size  and  each  was  carefully  examined  for  evidence  of 


IPalaeontologv,  Vol.  34,  Part  2,  1991,  pp.  241-281,  7 pls.| 


© The  Palaeontological  Association 


242 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  1.  Palaeocteniza  crassipes  Hirst.  1923.  a,  b,  two  views,  at  different  planes  of  focus,  of  the  holotype 
(and  only  known)  specimen  (BM(NH)  In  24670),  seen  from  the  left  side,  anterior  to  the  left,  x 130. 


spider  autapomorphies.  In  addition,  each  photograph  was  traced  seriatim  on  a graphics  pad  andnJie 
resultant  digitized  images  were  stacked  and  reconstituted  as  a rotatable  virtual  solid  using  the  Jandel 
computer  program  PC3D™  (see  below.  Methods).  We  had  hoped  that  James  Locke’s  efforts  to 
reconstruct  the  specimen  using  this  program  would  allow  us  to  examine  further  details,  but  this  was 
not  to  be.  The  level  of  resolution  attainable  was  too  low,  and  there  were  considerable  difficulties  in 
digitizing  the  images,  since  shallow  as  the  depth-of-field  was,  at  the  necessary  magnifications 
subjective  judgement  was  still  required  as  to  what  was  in  the  plane  of  focus  and  what  was  not, 
resulting  in  further  blurring  of  the  lines.  A careful  examination  of  the  specimen  itself  and  of  the 
serial  photographs  proved  to  give  the  most  information. 

The  general  condition  of  the  specimen,  much  crumpled  and  folded,  suggests  that  it  may  be  a 
moult.  Hirst  (1923)  noticed  a small,  thin,  scarcely  visible  object  dorsal  to  the  abdomen,  which  he 
supposed  to  be  the  detached  carapace.  Since  the  carapace  detaches  when  arachnids  moult,  if  this 
identification  is  correct,  its  presence  and  position  are  further  evidence  for  the  specimen  being  a cast 
exoskeleton.  The  prosoma  is  almost  entirely  concealed  behind  the  dorsally  flexed  legs  and  palps. 
While  the  palps  appear  to  be  complete,  all  of  the  legs  on  the  left  side  of  the  specimen  (facing  the 
viewer)  lack  their  distal  portions.  The  abdomen  is  complexly  crushed  and  folded. 

Hirst  (1923)  provided  a detailed  drawing,  which,  however,  incorporates  some  errors.  The 
proportions  of  the  right  palp  are  not  correct  in  comparison  with  the  left,  to  which  a segment  has 
been  added.  In  ‘restoring’  the  loose  piece  of  cuticle  to  its  supposed  position  as  carapace,  the 


SELDEN  ET  AL..  DEVONIAN  ARACHNIDS 


243 


mass  of  wrinkles  and  folds  above  the  leg  coxae  (perhaps  the  true  carapace)  has  been  omitted,  and 
some  of  the  folds  in  this  structure  appear  to  have  been  confused  with  parts  of  the  palps.  The  second 
or  third  left  leg  has  the  tibia  omitted.  In  the  region  of  the  supposed  abdomen.  Hirst  noted  that  what 
had  been  made  in  the  drawing  to  resemble  spinnerets  might  be  folds  of  cuticle.  This  is  definitely  so; 
the  apparent  internal  structures  of  the  abdomen  are  also  cuticular  folds  on  the  right  side  of  the 
specimen,  seen  through  the  left  side. 

In  attempting  to  determine  the  affinity  of  this  fossil,  a process  of  elimination  was  followed.  The 
general  appearance  and  structure  of  the  body  (a  prosoma  with  five  pairs  of  leg-like  appendages,  and 
an  abdomen  attached  by  a narrowed  portion)  establishes  that  it  is  an  arachnid,  and  that  it  may 
belong  to  the  known  orders  Araneae,  Amblypygi,  Uropygi,  Schizomida,  or  Trigonotarbida.  The 
presence  of  leg-like  (not  raptorial)  palps  rules  out  Amblypygi,  Uropygi,  and  Schizomida,  at  least  as 
they  are  presently  known. 

Devonian  trigonotarbids  differ  from  potentially  contemporaneous  spiders  in  a number  of  ways. 
While  both  groups  may  have  segmented  abdomens,  trigonotarbids  have  three  tergal  plates  per 
segment  and  lack  spinnerets.  The  eyes  of  any  contemporaneous  spiders  were  likely  to  have  been 
grouped  on  a centrally  located  tubercle,  as  in  the  modern  mesothele  spiders,  while  those  of 
Devonian  palaeocharinid  trigonotarbids  are  dispersed  in  three  groups:  a median  group  of  two,  and 
two  lateral  groups  which  may  consist  of  several  minor  and  major  lenses  each  (Shear  et  al.  1987).  All 
the  Devonian  trigonotarbids  we  have  examined  have  a simple  bicondylar  hinge  joint  between  the 
patella  and  tibia,  and  spiders  have  a monocondylar  rocking  joint  in  this  position. 

Close  examination  of  the  abdomen  of  the  specimen  failed  to  reveal  any  evidence  for  or  against 
segmentation  (despite  the  clear  segmental  lines  in  his  illustration.  Hirst  (1923,  p.  460)  wrote:  ‘...it 
is  impossible  to  be  quite  certain  whether  this  [the  abdomen]  is  segmented  or  not.’).  Thus  the  number 
of  tergites  that  might  be  present  for  each  segment  cannot  be  ascertained.  The  ‘spinnerets'  have 
already  been  alluded  to;  as  Hirst  inferred,  this  is  in  fact  a fold  of  the  abdominal  cuticle  that  can  be 
traced  continuously  until  it  merges  with  other  folds  of  the  structure.  The  entire  abdomen  was  also 
carefully  examined  for  spinnerets,  because  we  suspected  that  it  might  have  been  twisted  through 
180°,  and  because  in  living  mesothele  spiders  the  spinnerets  are  located  about  in  the  middle  of  the 
ventral  surface  of  the  abdomen,  which  is  supposedly  their  primitive  position.  We  found  no 
indication  whatsoever  of  spinnerets. 

Careful  focusing  revealed  that  among  the  crushed  mass  of  the  prosoma  was  an  object  that 
resembles  an  eye  tubercle  and  seems  to  bear  at  least  two  hemispherical  lens-like  protrusions. 
Unfortunately  this  evidence  is  inconclusive,  because  at  least  two  eye  lenses  would  be  present  on  a 
median  tubercle  both  in  trigonotarbids  and  spiders.  The  complicated  folding  and  distortion  of  the 
carapace  and  its  concealment  behind  the  legs  made  it  impossible  for  us  to  find  any  indication  of 
lateral  eye  groups. 

The  patella-tibia  articulation  can  be  seen  on  just  one  of  the  legs,  probably  the  left  third  leg.  It 
may  be  possible  to  make  out  two  dorsally  situated  articular  condyles  on  the  distal  end  of  the  patella, 
but  at  the  level  of  magnification  required  to  see  them,  the  optical  properties  of  the  chert  interfere 
significantly. 

In  summary,  the  fossil  carries  none  of  the  autapomorphies  of  spiders  that  could  be  seen  on  a 
specimen  of  this  size  and  level  of  preservation,  but  its  identity  as  a trigonotarbid  is  only  suggested 
(by  the  possible  pattern  of  patella-tibia  articulation).  It  should  be  pointed  out,  however,  that  scores 
of  trigonotarbids  have  been  seen  in  the  Rhynie  chert,  and  that  this  specimen  is  the  only  one  for 
which  a spider  identity  has  been  suggested.  Our  hypothesis  is  that  Palaeocteniza  crassipes  Hirst  is 
a moulted  exoskeleton  from  an  early  instar  trigonotarbid. 


ALKEN  ARCHAEOMETA 

One  of  only  four  fossil  sites  with  Devonian  terrestrial  animals,  Alken-an-der-Mosel,  Germany,  has 
yielded  impression  fossils  of  lower  Emsian  age,  including  trigonotarbids,  scorpions,  eurypterids, 
and  arthropleurids  (Stormer  1976;  Brauckmann  1987).  One  fossil  from  this  deposit,  Archaeometa? 


244 


PALAEONTOLOGY,  VOLUME  34 


devonica  Stormer,  1976,  was  identified  as  a spider  (Stormer  1976).  A policy  against  type-specimen 
loans  at  the  Senckenberg  Museum,  which  houses  this  specimen,  meant  that  we  were  unable  to 
examine  the  original.  However,  we  were  able  to  study  a plaster  cast,  and  the  photograph  and 
drawing  published  by  Stormer.  The  specimen  consists  of  an  elongate  blob  with  a few  transverse  lines 
at  one  end  and  a vaguely  indicated  region  at  the  other  which  may  be  part  of  some  plant  remains 
(Stormer  1976,  figs  48  and  49;  pi.  5,  fig.  2 a,b).  Stormer  indicated  that  he  had  before  him 
Petrunkevitch’s  drawing  of  Archaeometa  nephilina  Pocock,  1911,  from  the  Upper  Carboniferous  of 
Britain.  This  drawing  (Petrunkevitch  1949,  fig.  159)  shows  a featureless  carapace  with  seven  legs 
radiating  from  it,  and  an  elongate  abdomen  with  two  longitudinal  lines  and  four  or  five  terminal 
segments. 

There  are  two  similar  specimens  of  A.  nephilina  in  the  British  Museum  (Natural  History)  which 
were  examined  in  1986  by  W.A.S.,  and  subsequently  by  P.A.S.  Specimen  In  15863  is  the  more 
complete  and  was  the  specimen  figured  by  Petrunkevitch.  It  is  relatively  poorly  preserved  and  little 
can  be  added  to  the  diagrammatic  illustration  and  brief  description.  Specimen  In  31259,  the 
holotype,  does  not  show  the  transverse  ‘segmental'  lines  seen  in  In  15863.  The  cuticle  is  tuberculate 
and  the  abdomen  bears  longitudinal  folds;  neither  of  these  features  are  found  in  contemporaneous 
spider  fossils  (e.g.  Eocteniza  silivicola , figured  on  Pocock’s  pi.  II,  fig.  4),  but  are  more  reminiscent 
of  other  Carboniferous  arachnid  groups.  There  are  other  details  visible  on  this  specimen  which 
would  reward  a detailed  restudy.  Nevertheless,  there  are  no  features  which  would  distinguish  either 
of  these  specimens  as  a spider  rather  than  any  other  arachnid. 

In  any  case,  the  resemblance  of  Archaeometa?  devonica  to  these  two  specimens  is  vague  and 
probably  coincidental.  There  seems  to  be  no  reason  to  consider  Archaeometa?  devonica  as  a spider 
or  a fossil  arachnid  of  any  sort. 


THE  GILBOA  ARACHNIDS 

Early  reports  on  the  Gilboa  fauna  (Shear  et  al.  1984)  raised  the  possibility  of  spiders  being  among 
the  animals  present.  The  tip  of  an  arachnid  walking  leg  tarsus  was  illustrated,  and  diagnosed  as 
being  from  a spider  largely  on  the  basis  of  serrate  ventral  setae  similar  to  the  silk-handling  accessory 
claws  found  in  some  living  araneoid  spiders.  However,  in  later  studies,  the  possibility  of  spiders 
being  present  receded  as  it  became  clear  that  another  related  group  of  arachnids,  the  Trigonotarbida, 
dominated  the  fauna.  We  were  also  unable  to  demonstrate  conclusively  in  the  fossils  any 
autapomorphies  of  spiders.  Shear  et  al.  (1987),  in  a detailed  study  of  the  trigonotarbids,  assigned  all 
pulmonate  arachnid  fossils  from  Gilboa  to  this  extinct  order,  which  was  placed  as  the  plesiomorphic 
sister  group  to  the  other  pulmonate  orders.  One  animal  represented  only  by  legs  was  assigned  with 
some  doubt  to  the  trigonotarbid  genus  Gelasinotarbus,  and  given  the  species  epithet  fimbriunguis. 
This  name  referred  to  the  characteristic  claws,  set  with  ventral  cuticular  fimbriae,  not  found  in  any 
other  trigonotarbids.  Other  characters  in  these  legs,  present  but  undetected  in  1987,  we  now 
recognize  as  conclusive  evidence  of  a spider.  A single  femur  with  a patch  of  acute  spinules  near  its 
base  was  called  Arachnida  Incertae  sedis  B;  its  cuticle  is  similar  to  that  of  fimbriunguis,  and  other 
similar  femora  have  now  been  found  in  direct  connection  with  pieces  of  undoubted  fimbriunguis.  A 
third  group  of  specimens,  consisting  of  podomeres  and  cuticular  fragments,  was  referred  to 
Arachnida  Incertae  sedis  A.  Re-examination  of  these  specimens  and  of  new  material  with  the  same 
distinctive  cuticle  has  produced  evidence  that  they  belong  to  a pulmonate  arachnid,  close  to 
Amblypygi  and  Araneae.  To  complicate  matters  further,  the  tarsus  illustrated  as  a possible  spider 
in  Shear  et  al.  (1984,  fig.  1 b)  is  undoubtedly  trigonotarbid  ; it  has  smooth  claws  and  lacks  a tarsal 
organ. 

Late  in  1988,  conclusive  evidence  for  spiders  finally  turned  up  in  the  Gilboa  material:  a spinneret 
(Shear,  Palmer  et  al.  1989).  This  discovery  triggered  a search  for  other  possible  spider  parts,  and  it 
was  soon  realized  that  the  spinneret  belonged  with  the  legs  described  in  1987  as  Gelasinotarbus? 
fimbriunguis.  In  addition,  some  previously  unassigned  chelicerae  and  some  pieces  of  carapace  belong 
to  this  animal. 


SELDEN  ET  A L.  \ DEVONIAN  ARACHNIDS 


245 


The  ‘clasp-knife’  form  of  the  chilecera,  places  it  in  the  Pulmonata  ( = Arachnidea  sensu  van  der 
Hammen  1977;  made  up  of  the  orders  Trigonotarbida,  Uropygi,  Schizomida,  Amblypygi,  and 
Araneae).  Illustrated  here  for  comparison  are  chelicerae  of  the  uropygid  Mastigoproctus  giganteus 
(PI.  7,  fig.  5),  and  the  amblypygid  Heterophrynus  elaphus  (PI.  7,  fig.  6),  and  see  Shear  et  al.  (1987, 
figs  7,  67,  68)  for  photographs  of  trigonotarbid  chelicerae.  A number  of  characters  unequivocally 
place  the  chelicera  in  Araneae  (see  discussion  under  phylogenetic  relationships).  A cheliceral 
gland,  found  only  in  spiders,  is  present.  The  cheliceral  fang  of  A.fimbriunguis  lacks  setae,  which  are 
present  in  all  other  pulmonates.  In  all  other  orders  of  Pulmonata,  the  largest  cheliceral  teeth  are  at 
the  end  of  the  tooth  row  opposing  the  tip  of  the  fang  (subchelate  condition),  while  in  A. 
fimbriunguis,  as  in  the  vast  majority  of  spiders,  the  largest  teeth  occur  part-way  along  the  row  and 
nearer  to  the  fang  articulation  than  to  the  fang  tip  (the  subchelate  condition  occurs  in  a small 
number  of  spiders,  but  the  described  arrangement  is  found  only  in  spiders,  among  the  pulmonates). 
On  the  basis  of  outgroup  comparison  with,  for  example,  scorpions,  the  subchelate  state  is  primitive. 
Thus  there  are  three  definite  spider  synapomorphies  present  in  the  chelicera.  A significant 
apomorphy  of  spiders  is  the  presence  of  cheliceral  venom  glands.  Whilst  the  evidence  is  not  entirely 
certain,  in  at  least  two  specimens  of  A.  fimbriunguis  chelicerae  there  may  be  a subterminal  venom 
pore  near  the  fang  tip  (PI.  1,  fig.  7).  In  addition,  as  discussed  in  the  detailed  descriptions,  the 
articulations  present  make  it  clear  that  the  A.  fimbriunguis  chelicera  must  have  been  orthognath. 

The  legs  of  A.  fimbriunguis  bear  numerous  lyriform  organs;  only  in  spiders  are  lyriform  organs 
found  on  podomeres  other  than  the  metatarsi. 

The  pieces  of  carapace  are  referred  to  A.  fimbriunguis  on  the  basis  of  their  similarity  of  cuticular 
patterning. 

The  evidence  that  the  spinneret,  chelicera,  legs,  and  carapace  fragments  all  come  from  the  same 
morphospecies  is  overwhelming.  All  the  chelicerae  are  identical,  except  for  some  size  differences, 
and  all  of  the  podomere  types  (trochanter,  femur,  etc.)  are  identical  within  each  type.  All  specimens, 
including  the  spinneret  and  carapace  fragments,  have  the  same  distinctive  cuticular  ornamentation, 
a pattern  which  appears  in  no  other  Gilboa  specimens  except  those  that  can  be  unequivocally 
assigned  to  the  spider  on  the  grounds  given  above.  Finally,  the  chelicerae  and  basal  leg  podomores 
occur  in  organic  connection  on  a number  of  slides.  Therefore  these  Gilboa  specimens  are  considered 
to  belong  to  the  same  species,  Attercopus  fimbriunguis. 

There  are  numerous  fragments  of  cuticle  among  the  Gilboa  slides  which  resemble  the  cuticle  of 
A.  fimbriunguis  at  first  sight,  and  which  we  at  first  thought  could  belong  to  the  body  of  the  spider. 
Some  of  these  were  figured  by  Shear  et  al.  (1987)  and  referred  to  as  Arachnida  Incertae  sedis  A.  This 
animal  is  characterized  by:  generally  large  size;  scale-like  ornament  rather  than  reticulation;  setal 
sockets  which  range  from  small  to  very  large;  striated  macrosetae  and  thick,  striated,  bifid  spines 
(PI.  7,  figs  4 and  8);  groups  of  slit  sensilla  and  lyriform  organs;  ornamented  trichobothrial  base  on 
the  patella.  Minute,  c.  0 005  mm,  circular  organs  occur  on  the  cuticle  surface  and  appear,  at  low 
magnification,  similar  to  the  characteristic  little  slit  sensilla  of  Attercopus , but  examination  at  higher 
magnifications  reveals  a circular  hole  rather  than  a central  slit,  so  they  are  not  the  same  organ.  None 
of  these  minute  pores  bears  a seta,  and  their  function  is  unknown;  nevertheless,  the  difference  in 
morphology  from  the  little  slit  organs  of  Attercopus  gives  a useful  criterion  for  distinguishing  the 
two  cuticle  types.  New  information  on  Arachnida  Incertae  sedis  A has  been  discovered  during  the 
present  study,  and  the  animal  is  named  Ecchosis  pulchribothrium  gen.  et  sp.  nov.,  below.  The 
presence  of  lyriform  organs  suggests  that  E.  pulchribothrium  could  be  a spider,  but  the  distinctive 
ornamented  trichobothrial  socket  on  the  patella  is  puzzling.  Virtually  identical  trichobothrial 
sockets  are  found  on  the  living  amblypygid  Heterophrynus  elaphus  (PI.  7,  fig.  2),  but  this  animal  has 
a qi  ite  dilferent  leg  articulation  pattern  to  that  in  E.  pulchribothrium , and  a lyriform  organ  only  on 
the  metatarsus.  The  identity  of  E.  pulchribothrium  thus  remains  unclear,  but  we  suggest  that  it  is 
either  an  aberrant  amblypygid  or  a member  of  an  extinct,  undiagnosed  arachnid  order. 


246 


PALAEONTOLOGY,  VOLUME  34 


GEOLOGICAL  SETTING 


Stratigraphy 

The  fossils  occur  in  a grey  shale  in  the  upper  part  of  the  Panther  Mountain  Formation  at  a locality 
on  Brown  Mountain,  Gilboa,  Schoharie  Co.,  New  York  (7§'  quadrangle  sheet  6168  IV  NW  1945, 
approx.  271272  m N by  142951  m E;  Banks  et  al.  1985).  Further  locality  details  can  be  found  in 
Banks  et  al.  ( 1 972).  The  original  site  has  now  been  destroyed  to  make  way  for  a pump-storage  power 
plant  associated  with  Schoharie  Reservoir,  but  much  of  the  fossil-bearing  shale  was  removed  to  the 
Department  of  Biology,  State  University  of  New  York  at  Binghamton,  for  later  processing.  The 
Panther  Mountain  Formation  is  part  of  the  Hamilton  Group,  upper  Middle  Devonian  Erian  Series, 
and  is  equivalent  to  the  middle  Givetian  of  Europe. 

Palaeoecologv 

Detailed  discussion  of  the  taphonomy  and  palaeoecology  of  the  biota  is  given  in  Shear  (1986),  Shear 
et  al.  (1987)  and  Shear  and  Bonamo  (1988).  The  Gilboa  lithology  is  a dark  grey  mudstone.  The 
fauna  occurs  in  close  association  with  mats  of  interlocking  spiny  stems  of  the  lycopod  Leclercqia. 
Consideration  of  the  manner  of  preservation  of  the  plants  suggested  to  Banks  et  al.  (1985)  that  they 
were  buried  in  situ  by  low-energy  flood  waters.  Shear  et  al.  (1984)  suggested  that  the  animals,  which 
were  living  at  the  site  or  may  have  been  carried  in  by  the  flow,  came  to  rest  by  the  localized  reduction 
of  velocity  created  by  the  mesh  of  Leclercqia.  the  ‘natural  sieve’  effect  would  exclude  large  pieces 
of  arthropod  cuticle,  while  the  most  minute  particles  could  have  passed  through. 

Almost  all  the  arthropods  recovered  from  the  Gilboa  site  were  undoubtedly  terrestrial.  The  only 
exception  to  this  is  the  occurrence  of  eurypterid  fragments.  In  the  Devonian,  these  animals  lived  in 
both  marine  and  freshwater  aquatic  habitats,  and  some  were  amphibious  (Selden  1984,  1985),  so 
their  presence  in  the  Gilboa  mudstones  is  not  problematical.  In  addition  to  the  external  evidence 
of  sedimentology  and  associated  land  flora  for  the  habitat  of  the  arthropods,  palaeophysiology 
provides  further  proof  of  their  terrestriality  (Selden  and  Jeram  1989).  Trichobothria  are  fine  hairs 
sensitive  to  high-frequency  vibrations,  and  could  only  function  in  air.  They  occur  on  the  Gilboa 
pulmonates  Gelasinotarbus  bonamoae , G.  bifidus  (Shear  et  al.  1987,  figs  105-120),  and  Ecchosis 
pulchribothrium  (see  below),  and  the  pseudoscorpion  (Shear,  Schawaller  and  Bonamo  1989).  Book- 
lungs  for  air  breathing  occur  in  the  trigonotarbids  of  Gilboa  (Shear  et  al.  1987).  While  we  have  no 
evidence  of  trichobothria  or  book-lungs  in  the  Gilboa  spider  Attercopus , all  living  spiders  are 
terrestrial  apart  from  the  secondarily  aquatic  Argyroneta  aquatica , found  in  fresh  waters  of  Europe, 
and  the  littoral,  southern  hemisphere  Desidae.  The  phylogenetic  discussion  (below)  indicates  that 
if  Attercopus  were  aquatic,  it  would  also  have  been  secondarily  so,  since  all  other  Pulmonata  are 
primarily  terrestrial. 


MATERIAL  AND  METHODS 


Preservation 

The  animal  fossils  are  preserved  as  minute,  undistinguished,  brown  to  black  flakes,  which  are 
unrecognizable  as  animals  when  in  the  rock  and  under  incident  light  microscopy,  but  transmitted 
light  reveals  their  zoological  nature.  The  cuticle  appears  brown  in  transmitted  light,  and  the  depth 
of  colouration  is  directly  correlated  with  the  thickness  of  the  cuticle  (or  the  number  of  layers  of 
cuticle  superimposed  in  the  specimen).  The  chemical  composition  of  the  cuticle  is  not  known;  the 
brown  colouration  suggests  it  is  organic,  but  the  reduction  of  much  of  the  plant  material  in  the  same 
beds  to  carbon  indicates  the  likelihood  that  the  arthropod  cuticle  has  also  been  altered,  probably 
by  repolymerization  of  the  organic  molecules,  during  diagenesis.  The  arthropods  are  strongly 
compressed,  necessitating  the  use  of  special  techniques,  such  as  NDIC,  to  separate  overlapping 
layers  of  cuticle.  For  the  same  reason,  scanning  electron  microscopy  (SEM)  is  virtually  useless  for 
the  study  of  these  fossils,  revealing  only  surface  features:  both  original  structures  and  diagenetic 
effects. 


SELDEN  ET  AL.:  DEVONIAN  ARACHNIDS 


247 


The  fossils  are  fragmentary;  only  rarely  are  podomeres  and  other  parts  found  in  organic 
connection  with  others.  However,  the  occurrence  of  such  specimens  is  vital  for  the  correct 
identification  of  loose  podomeres  and  reconstruction  of  the  animals.  The  dearth  of  pieces  of 
carapace  and  abdomen  of  the  arachnids  can  be  explained  by  the  fact  that  podomeres  have  two 
surfaces,  so  that  when  compressed  together  they  remain  coherent  and  are  less  likely  to  fragment 
than  the  body  parts  which  consist  of  a single  sheet  of  cuticle.  The  carapace  and  abdomen  cuticle  is 
represented  by  the  many  ‘scraps’  which  occur  on  the  slides.  The  nearly  complete  trigonotarbid 
carapaces  and  abdomens  described  by  Shear  et  al.  (1987)  are  rare,  and  mostly  consist  of  both  left 
and  right  (or  dorsal  and  ventral)  surfaces  compressed  together. 

Further  discussion  of  the  preservation  of  the  Gilboa  fauna  is  given  in  Shear  et  al.  (1987). 

Methods 

The  specimens  were  recovered  from  the  rock  matrix  by  digestion  in  concentrated  hydrofluoric  and 
hydrochloric  acids  (see  Shear  et  al.  1987;  Shear  and  Bonamo  1988,  for  details).  After  washing  in 
distilled  water,  the  animal  fossils  were  separated  from  the  abundant  plant  fragments,  as  far  as 
possible,  and  mounted  in  CMC  or  Clearcol  on  plain  microscope  slides.  The  preparation  was  done 
in  the  laboratory  of  P.M.B.  in  Binghamton,  and  the  prepared  slides  were  then  sent  to  Hampden- 
Sydney  for  study  by  P.A.S.  and  W.A.S. 

The  slides  were  studied  using  an  Olympus  Vanox  II  biological  microscope  with  a Nomarski 
Differential  Interference  Contrast  (NDIC)  facility.  This  illumination  is  particularly  useful  at  high 
magnification  and  for  the  optical  separation  of  closely  adpressed  layers  of  cuticle.  Use  was  made 
of  an  Olympus  SZH  stereomicroscope  for  low  magnification  work,  particularly  on  comparative 
extant  material;  for  photography,  this  was  cleared  of  muscles  by  soaking  overnight  in  a solution  of 
potassium  hydroxide.  Camera  lucida  attachments  to  both  microscopes  facilitated  accurate  drawing 
of  the  specimens,  and  photographs  were  taken  on  35  mm  Kodak  Technical  Pan  film  at  ASA  50  with 
Olympus  PM  10  cameras  mounted  on  these  instruments.  On  plates  and  text-figures,  unless  stated 
otherwise,  all  photographs  were  taken  in  transmitted  light  with  NDIC  on  the  Vanox. 

The  computer  program  Jandel  PC3D™  (available  from  Jandel  Scientific,  2526  Bridgeway, 
Sausalito,  California  94965,  USA)  was  used  for  the  three-dimensional  reconstruction  of 
Palaeocteniza  crassipes , and  the  program  MacClade  2.1  (Maddison  and  Maddison  1987)  was 
extremely  useful  in  the  phylogenetic  analysis. 

Abbreviations  and  conventions  used  in  text-figures  are  as  follows;  a,  anterior,  antero-;  ar, 
articulation;  ch,  chelicera(l);  cl,  claw;  co  cx,  costa  coxalis;  cu.  cuticle;  Cx,  coxa;  d,  dorsal;  di,  distal; 
e,  edge;  f,  fold;  Fe,  femur;  gl,  gland;  i,  inferior,  infero-;  m,  arthrodial  membrane;  ma,  marginal; 
me,  median;  ms,  macroseta;  Mt,  metatarsus;  p,  posterior,  postero-;  pa  sp,  palpal  spinules;  Pa, 
patella;  pd,  paired;  po,  poison  duct  opening;  pr,  proximal;  ps,  prosoma;  r,  ridge;  s,  superior, 
supero-;  sc,  sclerite;  si,  slit  sensilla;  sr,  serrated;  st,  sternum,  su,  surface;  t b,  trichobothrial  base; 
Ta,  tarsus;  ta  or,  tarsal  organ;  Ti,  tibia;  Tr,  trochanter;  tv,  transverse;  v,  ventral;  X,  artefact. 

Unless  stated  otherwise  in  the  legend  to  camera  lucida  drawings:  dashed  lines  show  linear  features 
showing  through  cuticle  from  behind;  finely  dotted  areas  are  internal  surfaces;  coarse  dots  show 
arthrodial  membrane;  setal  sockets  and  slit  sensilla  (where  shown)  are  infilled  in  black  when  on 
surfaces  showing  through  from  behind;  prominent  spores  (where  shown)  are  in  black. 

Repository  ami  authorship 

Type  and  figured  material  is  deposited  in  the  Department  of  Invertebrates,  American  Museum  of 
Natural  History,  New  York  (numbers  prefixed  AMNH).  but  are  referred  to  in  the  text  by  their  slide 
numbers.  Most  slide  numbers  consist  of  a series  number  (the  first  two  numbers,  e.g.  411.7,  or  the 
first  only  if  only  two  numbers  are  present,  e.g.  329),  followed  by  the  number  of  the  slide  within  the 
series.  The  last,  slide,  number  is  prefixed  with  the  letters  AR  (or  Ar)  on  the  slide  itself,  and  quoted 
thus  in  earlier  publications;  these  letters  are  omitted  here  for  brevity.  The  slide  may  include  more 
than  one  specimen,  commonly  of  a different  arthropod,  but  quoting  the  slide  number  makes 
retrieval  of  specimens  for  future  study  easier,  facilitates  references  to  earlier  papers  on  the  Gilboa 


248 


PALAEONTOLOGY.  VOLUME  34 


table  1.  List  of  specimens  mentioned  in  text. 


Slide  No. 

AMNH  No. 

Illustration 

Brief  description 

A iter  copus  fimbriunguis 

329. 1 

43162 

PI.  3,  fig.  4;  Text-fig.  6d 

palpal  femur  + patella 

329.3 

43163 

PI.  3,  fig.  2;  Text-fig.  6 b 

femur 

329.3 

43163 

PI.  4,  fig.  1 ; Text-fig.  7a 

distal  tibia 

329.3 

43163 

PI.  4,  fig.  10;  Text-fig.  7f 

metatarsus 

329.38 

43168 

PI.  4.  fig.  8 

metatarsus 

329.39 

43098 

Text-fig.  12  b 

patella 

329.53 

43099 

PI.  4,  fig.  9 

tibia 

329.57 

43100 

Text-fig.  12  f 

metatarsus 

329.58 

43101 

Shear  et  al.  1987,  fig.  134 

holotype,  metatarsus,  tarsus 

329.59 

43102 

PI.  3,  fig.  3;  Text-fig.  6c 

distal  femur  + patella 

329.59 

43102 

Text-fig.  12c 

trochanter 

329.69 

43106 

PI.  2,  fig.  5;  Text-fig.  5e 

various;  femur,  patella,  tibia 

329.69 

43106 

PI.  6,  fig.  5;  Text-fig.  9d 

palpal  tarsus 

329 . 70 

43107 

Text-fig.  12  a 

paratype,  femur  + patella 

329.70 

43107 

Text-fig.  1 2 d,  e 

2 metatarsi,  proximal  tarsus 

329.16.34 

43164 

PI.  5,  fig.  2 

tarsus 

329.22.9 

43165 

PI.  1,  fig.  7;  Text-fig.  4e 

chelicera 

329. 31a. Ml 

43166 

PI.  3,  fig.  7;  Text-fig.  6e 

various;  femur  + patella 

329. 31a. M2 

43047 

PI.  6,  fig.  4 

legs 

334. la. 4 

43170 

PI.  5,  figs  1 and  3;  Text-figs  8a-c 

2 legs,  patella  to  tarsus 

334. la. 6 

43171 

PI.  2,  fig.  4;  Text-fig.  5d 

femur 

334. la. 7 

43172 

PI.  1,  figs  6 and  8;  Text-fig.  4c 

chelicera 

334. la. 8 

43173 

PI.  4,  figs  6;  Text-fig.  7e 

tibia 

334. la. 9 

43174 

PI.  2,  fig.  1 ; Text-fig.  5 a 

femur 

334.16. 12 

43175 

PI.  3,  fig.  5;  Text-fig.  6g 

distal  femur  + patella 

334.16.34 

43176 

Text-figs  10.  and  1 1 a,  b,  c 

spinneret 

334.16.38 

43177 

PI.  5,  fig.  5;  Text-fig.  8d 

tarsus 

334.16.86 

43178 

PI.  3,  fig.  6;  Text-fig.  6f 

femur  + patella 

411.02. 12M.6 

43179 

PI.  6,  figs  1 and  2;  Text-fig.  9 a 

metatarsus  + tarsus 

411.7.19 

43052 

paratype,  femur 

411.7.33 

43180 

PI.  1,  figs  4 and  5;  Text-fig.  4d 

chelicera 

411.7.45 

43181 

PI.  4,  fig.  3;  Text-fig.  7c 

distal  tibia 

411 . 19.83 

43182 

PI.  2,  fig.  2;  Text-fig.  5 b 

coxa 

411.19.98 

43183 

PI.  4,  fig.  7;  Text-fig.  7g 

distal  tibia 

411.19.102 

43184 

PI.  2,  fig.  7;  Text-fig.  5h 

3 coxae,  1 trochanter 

411.19.243 

43185 

PI.  3,  fig.  8 

proximal  femur 

411 . 19.248 

43186 

PI.  4,  fig.  5;  Text-fig.  7d 

patella 

411 . 19.250 

43187 

PI.  2,  fig.  8;  Text-fig.  5g 

coxa 

411 . 19.251 

43188 

PI.  4,  fig.  1 1 

metatarsus 

411.20.25 

43189 

PI.  4,  fig.  2;  Text-fig.  7 b 

patella 

2002.12.49 

43190 

PI.  4,  fig.  4 

tibia 

2002.12.79 

43191 

PI.  3,  fig.  1 ; Text-fig.  6a 

femur 

2002.12.90 

43192 

PI.  1,  figs  2 and  3;  Text-fig.  4 b 

cheliceral  teeth 

2002.12.102 

43193 

PI.  1,  fig.  1 ; Text-fig.  4a 

anterior  carapace 

Ecchosis  pulchribothrium 

411.1.33 

43194 

PI.  7,  fig.  I 

paratype,  distal  femur 

411.7.37 

43195 

PI.  6,  fig.  6;  Text-fig.  9 b 

holotype,  patella -Fprox.  tibia 

411.7.86 

43111 

Shear  et  al.  1987,  figs  149  and  150 

paratype,  distal  patella 

411.19.96 

43198 

PI.  6,  fig.  3;  Text-fig.  9c 

patella 

411 . 19.137 

43169 

PI.  7,  fig.  4 

large,  bifid  spine 

411 . 19.184 

43195 

PI.  7,  fig.  3 

lyriform  organ 

411 . 19.188 

43196 

PI.  7,  fig.  8 

paratype,  probable  tibia 

411.19.206 

43197 

PI.  7,  fig.  7 

sheet  of  cuticle 

2002.9.13 

43097 

PI.  2,  fig.  3;  Text-fig.  5 c 

coxa 

Arachnida  incertae  sedis 

334. la. 4 

43198 

PI.  5,  Fig.  3 

flagelliform  appendage 

2002.9.20 

43199 

PI.  5,  Fig.  4 

flagelliform  appendage 

SELDEN  ET  AL.:  DEVONIAN  ARACHNIDS 


249 


fauna  in  which  slide  numbers  are  used,  and  locates  the  specimen  to  the  original  rock  sample.  Thus 
it  will  be  possible  in  the  future  to  collate  data  on  the  whole  Gilboa  biota  to  a fine  degree  of  accuracy. 
Table  1 lists  the  described  specimens  both  by  their  AMNH  accession  number  and  the  slide  number. 
A complete  list  of  the  microscope  slides  which  bear  fragments  of  Attercopus  fimbriunguis,  Ecchosis 
pulchribothrium , and  Arachnida  incertae  sedis  is  deposited  as  Supplementary  Publication  No.  SUP 
14040,  5 pp.,  at  the  British  Library,  Boston  Spa,  Wetherby,  Yorkshire  LS23  7BQ,  England.  Copies 
of  this  can  be  obtained  by  writing  to  the  British  Library  at  the  above  address,  enclosing  prepaid 
coupons  available  from  most  libraries  throughout  the  world. 

In  addition  to  the  fossils,  the  following  material  (both  males  and  females,  and  from  the  W.  A. 
Shear  Collection,  unless  otherwise  stated)  of  extant  arachnids  was  studied  for  comparative 
purposes:  Araneae:  Liphistius  sumatranus  Thorell,  Sumatra,  American  Museum  of  Natural  History 
collection;  Amblypygi : Heterophrynus  elaphus  Pocock,  Ecuador;  Uropygi : Mastigoproctus 
giganteus  (Lucas),  Florida;  Schizomida:  species  indet.,  Mexico. 

Following  previous  practice  (Shear  el  al.  1987),  authorship  of  new  taxa  is  attributed  to  Selden  and 
Shear.  Bonamo  discovered  and  supervised  the  preparation  of  the  Gilboa  material ; Selden  and  Shear 
are  responsible  for  other  information  and  ideas  in  this  paper. 


RECONSTRUCTION  OF  THE  GENERALIZED  LEG  OF  ATTERCOPUS 

The  reconstruction  (Text-fig.  2)  reflects  a combination  of  the  known  morphology  of  various  legs, 
some  of  which  are  suspected  to  be  leg  1 by  their  close  relationship  with  palpal  femora  and  chelicerae, 
but  for  most  specimens  the  leg -to  which  they  belong  is  not  known.  The  reconstruction  is  to  be  used 
as  a key  to  interpretation  of  the  fossils,  and  for  comparative  purposes  in  a general  sense.  However, 
it  must  be  remembered  that  no  one  leg  of  Attercopus  fimbriunguis  looked  exactly  like  this 
reconstruction,  and  in  particular,  the  relative  proportions  of  the  podomeres  would  have  varied 
between  legs. 

There  are  a number  of  ways  in  which  the  orientation  of  podomores  can  be  inferred.  Inferior  and 
superior  are  fairly  straightforward : comparison  of  the  articulation  points  with  those  of  living 
spiders,  together  with  a consideration  of  the  way  the  leg  has  to  work  as  a functional  unit,  is  normally 
sufficient.  Assessing  which  is  anterior  and  which  posterior  is  less  easy.  The  trochanter  can  be 
oriented  by  observing  its  relationship  to  the  coxa,  the  orientation  of  which  is  known  because  of  the 
asymmetry  in  the  joint  and  comparison  with  extant  arachnids.  However,  there  are  no  trochanters 
connected  to  femora  which  are  sufficiently  well  preserved  to  enable  the  following  of  the  orientation 
down  the  leg.  Since  most  joints  beyond  the  coxa  are  symmetrical,  their  morphology  is  of  little  use 
in  orientation,  but  there  is  an  asymmetrical  distribution  of  slit  sensilla  and  lyriform  organs  around 
the  distal  joints  of  podomeres.  The  palpal  femur  bears  a patch  of  spinules  in  an  inferior  position, 
to  one  side  of  its  sagittal  plane.  The  function  of  these  spinules  is  not  known,  but  we  are  assuming 
that,  whatever  their  function  (see  below),  they  are  most  likely  to  occur  on  the  anterior  side  of  the 
podomere.  Therefore,  the  palpal  femur  can  be  oriented,  and  since  this  podomere  is  attached  to  a 
patella,  this  podomere  can  also,  and  so  on  down  the  leg.  A further  logical  step  is  required  in  the 
assumption  that  the  apparent  similar  distribution  of  slit  sensilla  on  palpal  podomeres  and  on  the 
podomeres  of  other  legs  reflects  a real  serial  homology.  These  assumptions  have  only  been  made  in 
order  to  provide  an  orientation  for  the  reconstructed  generalized  leg,  and  not  for  any  other  purpose. 
Should  the  orientation  prove  to  be  incorrect,  then  the  references  to  anterior  and  posterior  would 
simply  require  reversal. 

PHYLOGENETIC  RELATIONSHIPS  OF  ATTERCOPUS  F1M BRIUNGUS 
Cladistic  analysis 

Characters  and  character  states  used  in  the  analysis  are  listed  in  Table  2,  the  data  matrix  is  given 
in  Table  3,  and  the  cladogram  in  Text-figure  3.  The  tree  was  rooted  by  arbitrarily  including  an 
ancestor  plesiomorphic  for  all  characters. 


250 


PALAEONTOLOGY,  VOLUME  34 


a si 


text-fig.  2.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  A,  reconstruction  of  a typical  walking  leg, 
posterior  aspect,  b,  diagrammatic  representation  of  walking  leg  joints,  distalmost  to  the  left;  each  joint  is 
viewed  from  the  distal  direction  with  the  anterior  to  the  left,  the  inner  circle  representing  the  distal  podomere, 
the  outer  the  proximal  podomere;  solid  circles  are  articulation  points  and  straight  lines  are  articulation  axes, 
short  lines  represent  slit  sensilla.  The  body-coxa  joint  is  highly  diagrammatic;  the  lower  articulation 
representing  the  coxosternal  attachment,  the  upper  triangle  representing  the  attachment  of  the  coxa  to  the 
prosomal  marginal  cuticle.  The  upper  coxa-trochanter  articulation  is  a movable  sclerite  set  in  the  arthrodial 
membrane,  which  allows  rocking.  Slit  sensilla  omitted  from  coxal  distal  joint.  The  trochanter-femur  joint  is 
a horizontal  pivot.  The  femur-patella  joint  is  a superior  bicondylar  hinge,  and  there  is  a sclerite  embedded  in 
the  inferior  arthrodial  membrane.  The  patella-tibia  joint  has  a superior  articulation,  but  a close  connection  of 
the  podomeres  inferiorly  allows  the  joint  to  work  as  a loose  vertical  pivot.  The  tibia-metatarsus  joint  is  a 
superior  bicondylar  pivot.  The  metatarsus-tarsus  joint  bears  antero-  and  posterosuperior  articulations  forming 
a superior  bicondylar  hinge,  but  the  joint  may  be  uncoupled  on  relaxation  of  the  muscles,  allowing  rocking. 


Shear  et  al.  (1987)  presented  a cladistic  analysis  based  on  23  of  the  same  characters  as  used  here. 
The  additional  characters  accommodate  the  division  of  the  Araneae  into  Attercopus , Mesothelae, 
Mygalomorphae,  and  Araneomorphae.  If  a character  is  not  discussed  below,  the  discussion  will  be 
found  in  the  1987  paper.  Some  of  the  previously  used  23  characters  have  been  re-evaluated;  in  the 
following  discussion,  the  character  number  given  is  from  Table  2,  and  the  character  number  from 
Shear  et  al.  (1987)  is  in  brackets. 

Original  characters.  Character  8 [5]  has  been  recoded.  Further  investigation  of  the  patella-tibia  articulation 
demonstrated  that  the  joint  in  living  spiders  has  an  additional  specialization,  compression  zone  Y (CZY,  see 
later),  not  present  in  Attercopus.  Further,  while  the  joint  is  immobilized  (fixed)  in  Amblypygi,  considerable 
movement  is  possible  at  that  articulation  in  legs  2-4  of  Uropygi  and  Schizomida  (in  leg  1 the  patella  and  tibia 
are  entirely  fused  without  trace  of  a suture).  We  do  not  know  if  the  condition  on  the  more  posterior  legs  of 
Uropygi  and  Schizomida  represents  a reversal  or  the  retention  of  a primitive  condition,  but  we  decided  to  code 
it  as  a primitive  retention  on  the  grounds  of  parsimony.  Character  9 [16]  has  also  been  recoded,  because  an 


SELDEN  ET  AL.  DEVONIAN  ARACHNIDS 


251 


table  2.  Characters  and  character  states  used  in  the  phylogenetic  analysis. 


Characters 

Plesiomorphic  state 

Apomorphic  state 

1. 

cheliceral  segmentation 

3-segmented 

2-segmented 

2. 

plagula  ventralis 

absent 

present 

3. 

book-lungs 

absent 

present 

4. 

sperm  flagellum 

9 + 2 

9 + 3 

5. 

segment  7 

broad 

narrowed 

6. 

eggs 

not  protected 

protected  by  secretions 

7. 

lateral  eyes 

minor  lenses  present 

minor  lenses  absent 

8. 

Pa-Ti  joint 

bicondylar  hinge 

1,  rocking,  no  CZY 

2,  rocking  with  CZY 

3,  immovable 

9. 

labium 

absent 

present 

10. 

grouped  slits/lyriforms 

absent 

present 

11. 

tarsal  organ 

absent 

present 

12. 

cheliceral  poison  gland 

absent 

present 

13. 

silk  glands 

absent 

present 

14. 

tibial  lyriforms 

absent 

present 

15. 

cheliceral  fang 

setose 

naked 

16. 

cheliceral  gland 

absent 

present 

17. 

male  palp 

unmodified 

modified 

18. 

abdominal  segments 

visible 

hidden 

19. 

tartipores 

absent 

present 

20. 

sternum 

broad,  unitary 

reduced,  divided 

21. 

palps 

leg-like 

raptorial 

22. 

leg  1 

leg-like 

antenniform 

23. 

posterior  sucking  stomach 

present 

absent 

24. 

abdominal  flagellum 

absent 

present 

25. 

palp  coxae 

free 

fused 

26. 

postabdomen 

2-segmented 

3-segmented 

27. 

abdominal  tergites 

entire 

divided 

28. 

fimbriae  on  claws 

absent 

present 

29. 

spinules  on  palpal  Fe 

absent 

present 

30. 

Ti-Mt  organ 

absent 

present 

31. 

clavate  trichobothria 

absent 

present 

32. 

anterior  media  spinnerets 

absent 

1,  present 

2,  lost 

33. 

chelicerae 

orthognath 

labidognath 

34. 

cleaning  brush  on  palp 

absent 

present 

35. 

anal  glands 

absent 

present 

36. 

male  flagellum 

unmodified 

modified 

37. 

central  nervous  system 

partly  in  abdomen 

wholly  in  prosoma 

38. 

trichobothria 

present 

absent 

examination  of  specimens  has  convinced  us  that  a labium  (sternite  of  the  palpal  segment  modified  as  a lower 
lip)  does  not  in  fact  occur  in  Amblypygi,  Uropygi,  and  Schizomida.  In  amblypygids,  a long  projection  goes 
forward  from  the  sternite  of  the  first  leg,  but  could  not  function  as  a labium.  In  uropygids  and  schizomids,  the 
palpal  sternum  is  an  immovable  pentagonal  sclerite  and  the  ventral  wall  of  the  preoral  cavity  (camerostome) 
is  formed  by  the  fused  palpal  coxae.  Character  5,  the  narrowing  of  segment  7,  has  replaced  [18]:  presence  or 
absence  of  a pedicel.  We  think  that  the  key  feature  here  is  the  reduction  in  width  of  that  segment,  which  occurs 
to  a greater  (Araneae,  Amblypygi)  or  lesser  (Trionotarbida,  Uropygi,  Schizomida)  degree  in  all  of  the  taxa 
involved. 


252 


PALAEONTOLOGY,  VOLUM  E 34 


table  3.  Data  matrix  used  in  the  phylogenetic  analysis.  0 = plesiomorphic  state,  1 = apomorphic  state, 
2,  3 = alternative  apomorphic  states,  ? = character  state  uncertain.  See  text  for  details. 


Characters 

12345 

1 

67890 

12345 

2 

67890 

12345 

3 

67890 

12345 

678 

Trigonotarbida 

11171 

?0000 

00000 

00000 

00?00 

01000 

00000 

0?1 

Attercopus 

111?? 

??1?1 

urn 

l??0? 

00  ??0 

??1 10 

0?000 

0?1 

Mesothelae 

mu 

1 121 1 

urn 

1 1000 

00000 

00001 

11000 

010 

Mygalomorphae 

mu 

1 121 1 

mu 

11110 

00000 

00000 

02000 

010 

Araneomorphae 

mu 

11211 

m 1 1 

11110 

00000 

00000 

01100 

010 

Amblypygi 

mu 

1 1301 

10000 

00001 

11000 

00000 

00010 

010 

Uropygi 

mu 

11101 

10000 

00001 

mu 

10000 

00001 

000 

Schizomida 

mu 

11101 

10000 

00001 

urn 

10000 

00000 

100 

New  characters. 

Characters  10  and  14: 

slit  sensilla 

are  unique 

to  chelicerates.  We 

have  assumed 

. that  the 

primitive  arrangement  was  scattered,  single  slits  on  most  or  all  body  surfaces,  and  these  still  occur  in  all 
arachnids.  However,  the  slits,  which  function  as  cuticular  strain  gauges,  are  found  in  greater  numbers  near 
articulations  or  points  where  the  cuticle  is  likely  to  be  stressed  (Barth  1978,  1985).  This  has  led  in  turn  to  the 
formation  of  loosely  organized  groups  of  slits,  and  thence  to  tightly  coupled,  parallel  slits,  commonly 
surrounded  by  a cuticular  border,  known  as  lyrifornr  organs.  In  true  lyriform  organs  the  slit  sensilla  are 
neurally  integrated  to  act  as  a single  organ;  this  integration  is  recognized  morphologically  where  the  slits  are 
as  close  together  as  their  individual  widths,  and  are  parallel  to  each  other.  They  may  change  in  length  gradually 
across  the  organ,  giving  the  appearance  of  the  arrangement  of  strings  in  a lyre  or  harp.  A multiplicity  of 
lyriforms  is  clearly  apomorphic,  and  in  character  14,  the  presence  of  lyriforms  on  the  leg  tibiae  stands  in  for 
this  increase  in  their  number.  In  trigonotarbids,  we  have  not  detected  grouped  slits  or  lyiforms,  though  large 
slits  occur  in  greater  numbers  near  the  distal  ends  of  podomeres  (see  Shear  et  al.  1987,  figs  1 1.  46,  79-81). 
Lyriforms  occur  in  amblypygids  and  uropygids  only  on  the  distal  ends  of  the  metatarsi  of  legs  2-4,  and  are 
oriented  parallel  to  the  long  axis  of  the  leg;  spiders  have  this  metatarsal  lyriform,  which  is  oriented 
perpendicular  to  the  long  axis  of  the  leg,  as  well  as  many  additional  lyriforms  on  other  podomeres  which  are 
oriented  parallel  to  the  long  axis  (Barth  1985;  Barth  and  Stagl  1976;  Moro  and  Bali  1986). 

Character  1 I : typical  tarsal  organs  (Blumenthal  1935;  Forster  1980)  occur  on  the  walking  leg  tarsi  of  all 
living  Pulmonata  (Amblypygi  and  spiders,  Forster  1980.  and  pers.  obs. ; antenniform  legs  of  Amblypygi,  Foelix 
et  al.  1975  (‘pit  organ');  walking  legs  of  Uropygi,  pers.  obs.  and  R.  Forster,  pers.  comm.;  walking  legs  of 
Schizomida,  pers.  obs.  and  R.  Forster,  pers.  comm.).  We  have  not  detected  this  organ  on  the  tarsi  of 
trigonotarbids,  but  it  is  present  in  Attercopus.  While  similar  structures  are  found  on  the  tarsi  of  scorpions  and 
ticks  (Foelix  and  Axtell  1972;  Foelix  and  Schabronath  1983),  they  appear  ultrastructurally  different  and  their 
homology  has  not  been  established.  Thus  the  presence  of  the  tarsal  organ  is  treated  here  as  a synapomorphy 
for  the  orders  of  Pulmonata  excepting  Trigonotarbida,  though  it  may  later  be  shown  to  be  more  widespread 
in  Arachnida. 

Character  15:  a naked  cheliceral  fang  is  apomorphic  by  comparison  with  the  setose  condition  of  the  palp 
and  walking  legs,  with  which  the  chelicera  is  serially  homologous.  Among  the  Pulmonata,  a naked  cheliceral 
fang  is  found  only  in  spiders,  al!  other  pulmonate  orders  have  a brush  of  setae  on  the  fang  (see,  for  example, 
PI.  7.  figs  5 and  6;  Shear  et  al.  (1987)  figs  7,  67,  68). 

Character  16:  the  cheliceral  gland  described  by  Forster  and  Platnick  (1984)  has  been  reported  only  in 
spiders;  it  has  been  found  in  all  species  so  far  examined  from  a wide  selection  of  families  (R.  Forster,  pers. 
comm.).  Raymond  Forster  (pers.  comm.)  stated  that  he  has  found  a series  of  scattered  pores  near  the  midpoint 
of  the  ventral  surface  of  the  chelicera  in  amblypygids,  which  he  considers  a cheliceral  gland.  Using  light 
microscopy  (including  oil  immersion  examination  of  cleared  cuticle)  we  were  not  able  to  confirm  these 
observations,  but  a purposeful  search  for  the  gland  may  reveal  it  in  orders  other  than  Araneae.  In 
pseudoscorpions,  glands  also  open  on  the  chelicera  (Vachon  1966),  but  they  are  very  distinct  in  appearance  and 
probably  not  homologous.  We  propose  the  presence  of  this  distinctive  gland  is  yet  another  autapomorphy  for 
the  order  Araneae. 

Character  18;  in  opisthothele  spiders,  the  segmentation  of  the  abdomen  is  suppressed  and  is  either  entirely 


SELDEN  ET  AL..  DEVONIAN  ARACHNIDS 


253 


concealed  from  external  view,  or  revealed  only  on  the  maturity  of  males  of  a few  species  of  mygaloniorphs,  and 
even  then  only  in  the  anterior  part.  This  is  a synapomorphy  for  Mygalomorphae  and  Araneomorphae. 

Character  19:  tartipores  - these  peculiar  structures,  like  small,  collapsed  pastries  (hence  the  name),  evidently 
mark  the  position  of  spigots  on  the  spinnerets  in  previous  mstars  (Kovoor  1986;  Coddington  1989).  They  do 
not  occur  in  Attercopus  nor  in  mesotheles  (pers.  obs.  on  Liphistius  sumatranus  and  L.  malayanus).  The  number 
of  spigots  on  spider  spinnerets  increases  with  each  instar;  in  mesotheles  the  increase  is  accomplished  by  adding 
more  pseudosegments  to  the  spinneret.  We  consider  this  mechanism  primitive,  and  the  presence  of  tartipores 
synapomorphic  for  mygalomorph  and  araneomorph  spiders. 

Character  26:  a two-segmented  postabdomen  is  present  in  trigonotarbids,  spiders,  and  amblypygids. 
Counting  segments  shows  that  uropygids  and  schizomids  have  added  a third,  basal  segment  (probably  by  the 
narrowing  of  the  segment  just  in  front  of  the  primitive  two-segmented  postabdomen),  which  we  consider  a 
synapomorphy  for  that  group,  correlated  with  the  postanal  abdominal  flagellum. 

Characters  28  and  29:  fimbriate  claws  and  palpal  femoral  spinules  are  autapomorphies  of  Attercopus,  by 
outgroup  comparison  and  the  criterion  of ‘special  structures’. 

Characters  30  and  31 : a highly  specialized  organ  for  detecting  deflection  of  the  metarsus  with  respect  to  the 
tibia  is  present  among  spiders  only  in  living  mesotheles  (Platnick  and  Goloboff  1985).  Likewise,  special  club- 
shaped  trichobothria  (Foelix  1985)  are  unique  to  this  group  (Platnick  and  Goloboff  1985). 

Character  32:  by  outgroup  comparison,  the  loss  of  the  anterior  median  spinnerets  is  autapomorphic  for 
mygalomorph  spiders.  We  might  add  here  that  there  are  other  spinneret  and  spigot  characters  that  may  prove 
useful  for  phylogenetic  analysis  among  spiders;  some  of  these  have  already  been  described  by  Coddington 
(1989)  and  others  are  under  study  by  J.  M.  Palmer  and  J.  A.  Coddington. 

Character  33 : labidognath  chelicerae  are  found  only  in  araneomorph  spiders  and  are  autapomorphic  for  that 
group. 

Character  38:  the  distribution  of  trichobothria  in  the  Arachnida  has  been  discussed  by  Kaestner  (1968),  and 
Reissland  and  Gorner  (1985).  They  are  found  in  spiders,  amblypygids,  uropygids,  schizomids,  palpigrades, 
scorpions,  pseudoscorpions,  and  mites,  but  not  in  solifuges,  ricinuleids,  or  opihonids.  Their  occurrence  in 
scorpions  and  palpigrades,  both  considered  primitive  arachnids,  and  their  general  appearance  elsewhere  argues 
for  considering  their  absence  in  any  arachnid  a loss.  We  have  not  found  trichobothria  in  trigonotarbids,  nor 
in  Attercopus.  Shear  et  al.  (1987)  described  trichobothria  in  the  supposed  trigonotarbid  Gelasinotarbus 
bonamoae , but  new  studies  of  this  animal  have  convinced  us  that  it  is  not,  after  all,  a trigonotarbid,  nor  does 
it  seem  to  be  a spider.  The  loss  of  trichobothria  is  thus  proposed  as  another  autapomorphy  for  Trigonotarbida. 

We  are  more  concerned  about  the  complete  lack  of  trichobothria  encountered  during  our  high-magnification 
studies  of  well-preserved  podomeres  of  Attercopus.  We  have  found  no  mention  in  the  literature  of  spiders 
without  trichobothria,  and  R.  Forster  and  N.  Platnick,  who  have  surveyed  hundreds  of  species  using  SEM, 
reported  that  they  have  found  no  spiders  which  lack  these  sense  organs  (R.  Forster,  pers.  comm.).  Had  we  not 
found  tarsal  organs  and  longitudinally  oriented  lyriforms  on  Attercopus  podomores,  as  well  as  having  been  able 
to  match  their  cuticle  to  that  of  the  isolated  spinneret,  we  would  question  our  assignment  of  these  fossils  to 
Araneae.  We  must  regard  the  loss  of  trichobothria  in  Attercopus  as  an  autapomorphy  independent  of  their  loss 
in  trigonotarbids. 


Cladogram.  Using  these  38  characters,  we  have  produced  a 36-step  cladogram  (Text-fig.  3)  with  a 
consistency  index  of  0 97. 

In  an  earlier,  preliminary  report  on  the  spinneret  of  Attercopus  fimbriunguis,  Shear,  Palmer  et  al. 
(1989),  were  able  to  narrow  down  the  number  of  possible  cladograms  for  spider  sub-  and  infra- 
orders to  three,  arguing  as  follows.  Recent  views  of  spider  evolution  divide  the  Order  Araneae  into 
two  suborders.  Suborder  Mesothelae  includes  a small  number  of  species  today  restricted  to 
southeast  Asia,  Indonesia,  and  Japan;  they  are  united  by  a number  of  synapomorphies,  including 
a peculiar  sense  organ  between  the  tibiae  and  metatarsi  of  the  legs  (see  above).  Mesotheles  are  better 
known  to  arachnologists  for  their  primitive  characters,  including  an  externally  segmented  abdomen 
and  the  possession  of  eight  (rarely  seven)  spinnerets,  which  are  located  not  at  the  end  of  the 
abdomen,  but  near  the  middle  of  its  ventral  surface.  Suborder  Opisthothelae  includes  all  other 
spiders,  in  which  the  number  of  spinnerets  has  been  reduced  to  six,  four,  or  two  and  moved  to  the 
posterior  end  of  the  abdomen,  which  is  not  externally  segmented.  Within  this  group, 
Mygalomorphae  (‘tarantulas’  in  the  North  American  sense)  have  lost  all  vestiges  of  the  anterior 
median  spinnerets,  while  Araneomorphae  carry  a cribellum  (repeatedly  lost  in  many  lines) 


254 


(0 

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IS 


PALAEONTOLOGY,  VOLUME  34 


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text-fig.  3.  Cladogram  of  relationships  between  Attercopus  gen.  nov.,  infraorders  of  Araneae,  and  orders  of 
Pulmonata,  as  inferred  by  the  cladistic  analysis  (see  text  for  details).  The  cladogram  has  a length  of  36  and  a 

consistency  index  of  0-97. 


homologous  to  the  anterior  median  spinnerets  of  mesotheles,  and  have  chelicerae  rotated  to  the 
labidognath  position,  so  that  the  fangs  point  toward  one  another. 

The  spinneret  is  described  in  detail  below.  Using  information  from  the  description.  Shear,  Palmer 
et  al.  (1989)  were  sure  the  spinneret  could  not  have  come  from  the  living  clade  of  mesotheles, 
because  in  mesotheles  the  large  lateral  spinnerets  of  each  pair  are  pseudosegmented,  with  spigots  in 
ranks  of  2,  3,  or  4 on  the  mesal  surface  of  a pseudosegmental  ring,  and  the  smaller,  single-articled 
median  ones  bear  only  a single  spigot.  Because  the  Devonian  spinneret  is  not  pseudosegmented,  yet 
bears  more  than  one  spigot,  it  could  not  have  come  from  a mesothele  spider  similar  to  those  living 
today. 

Araneomorph  spiders  are  ruled  out  because  the  spigots  of  their  spinnerets  are  strongly 
differentiated  from  one  another  and  from  those  of  mygalomorph  spiders  in  characteristic  ways,  and 
all  spigots  on  the  fossil  specimen  are  of  the  same  size  and  shape. 

Mygalomorph  spiders  have  single-articled  posterior  median  spinnerets  with  numerous  spigots 
arranged  as  they  are  in  the  fossil.  The  presence  of  undifferentiated,  or  only  weakly  differentiated, 
spigots  that  are  more  densely  clustered  near  the  tip  of  the  spinneret  is  consistent  with  mygalomorph 
spider  posterior  median  spinneret  anatomy.  However,  both  mygalomorph  and  araneomorph 
spinnerets  have  peculiar  nipple-shaped  structures  called  tartipores  (see  above),  which  represent  the 
positions  of  spigots  in  previous  instars.  Tartipores  are  not  present  on  the  Devonian  spinneret.  In 
addition,  mygalomorph  spinnerets  usually  have  two  types  of  spigots  present. 

Finally,  the  form  of  the  spigots  themselves  does  not,  in  detail,  agree  with  that  of  mygalomorph 
spigots.  Mygalomorph  spigots  usually  have  an  articulated  shaft,  which  joins  the  base  by  means  of 
a well-defined,  sleeve-like  fold.  At  least  the  distal  third  of  the  shaft  has  sculpture.  However,  the 
rastelloid  clade  of  mygalomorphs  have  non-articulated  shafts  and  extremely  fine  sculpture,  visible 
only  when  viewed  with  the  SEM.  Diagenetic  changes  in  the  fossil  spinneret  may  have  made  it 
impossible  to  resolve  such  fine  detail  as  the  distal  shaft  sculpture. 

Mesothele  spigots,  on  the  other  hand,  are  uniform  in  morphology,  with  a broad,  conical  base  and 
a long,  gradually  tapering,  unsculptured  distal  shaft  that  merges  smoothly  into  the  base.  The  spigots 
of  the  fossil  are  of  this  type.  Considering  the  absence  of  tartipores,  of  a sleeve-like  fold  at  the  base 


SELDEN  ET  AL.  DEVONIAN  ARACHNIDS 


255 


of  the  spigot  shaft,  and  the  likelihood  that  distal  sculpture  is  absent,  the  spigots  are  more  like 
mesothele  spigots  than  mygalomorph  ones. 

Therefore,  the  combinations  of  apomorphies  found  in  the  three  living  clades  would  seem  to 
exclude  the  fossil  from  all  of  them.  The  problem  then  becomes  placement  of  the  fossil  as  a sister 
group  of  one,  two  or  all  of  these  clades.  The  presently  accepted  3-taxon  statement  for  the  groups 
of  spiders  so  far  discussed  is:  Mesothelae  (Mygalomorphae  (Araneomorphae)).  The  fossil  spinneret 
is  probably  not  from  a spider  belonging  to  the  sister  group  of  either  Araneomorphae  or 
Mygalomorphae,  because  to  place  it  in  either  of  those  positions  would  require  the  ad  hoc  secondary 
loss  of  tartipores  in  the  fossil  clade.  Thus,  either  Attercopus fimbriunguis  would  prove  to  be  the  sister 
group  of  all  other  spiders,  of  only  mesotheles,  or  of  opisthotheles,  leaving  a basal  trichotomy  in  the 
cladogram  of  spider  suborders.  Shear,  Palmer  et  al.  (1989)  ended  their  argument  at  this  point, 
because  additional  Attercopus  fragments  had  not  yet  been  identified,  and  no  characters  were 
available  to  resolve  the  trichotomy. 

Careful  examination  of  the  legs  of  A.  fimbriunguis  has  provided  evidence  that  the  trichotomy  can 
be  resolved  in  favour  of  this  Devonian  clade  as  the  sister  group  of  all  other  spiders.  This  evidence 
comes  from  the  structure  of  the  patella-tibia  joint,  which,  as  we  (Shear  et  al.  1987)  and  others 
(Manton  1977;  van  der  Hammen  1977,  1985,  1986;  Shultz  1989)  have  shown,  is  of  great 
phylogenetic  significance. 

In  trigonotarbids,  this  joint  is  a simple  bicondylar  hinge,  probably  the  plesiomorphic  form  at  least 
for  Pulmonata  (Shear  et  al.  1987).  In  the  other  pulmonate  orders,  it  becomes  a specialized  rocking 
joint,  with  a single  dorsal  condyle  and  held  together  with  strong  muscles.  In  spiders,  three  lyriform 
organs  are  found  on  the  posterior  surface  and  two  on  the  anterior,  and  this  rich  array  of 
proprioceptors  is  associated  with  the  complex  movement  of  this  joint  in  more  than  one  plane 
(Manton  1977).  The  additional  complex  mobility  of  the  patella-tibia  joint  is  conferred  at  least  in 
part  by  a posterior  emargination,  occupied  by  lightly  sclerotized  cuticle  and  extending  proximally 
from  the  distal  edge,  which  Manton  called  ‘compression  zone  Y’  (CZY).  The  presence  of  CZY 
pushes  the  middle  lyriform  of  the  three  posterior  ones  almost  to  the  proximal  edge  of  the  podomere. 
However,  in  amblypygids,  this  joint,  while  retaining  vestiges  of  the  rocking  articulation,  is  nearly 
immobile.  In  uropygids  and  schizomids  the  first  leg  patellae  and  tibiae  are  entirely  fused  and  no 
separate  patella  appears.  On  the  walking  legs  (2-4)  the  joint  is  movable,  but,  as  discussed  above, 
we  are  not  certain  if  this  mobility  is  primary  or  secondary. 

The  condition  of  this  joint  in  A . fimbriunguis  is  of  great  interest ; the  rocking  articulation  is  present 
but  CZY  is  absent.  Functionally,  this  suggests  substantially  less  mobility  at  this  joint  than  in  other 
spiders,  but  more  than  in  trigonotarbids. 

It  is  suggested  that  the  common  ancestor  of  Araneae  and  the  ‘pedipalp’  orders  (Uropygi, 
Ainblypygi,  Schizomida)  had  the  type  of  joint  found  in  A.  fimbriunguis,  which  is  still  present  in 
Uropygi  and  ‘locked’  in  the  legs  of  Amblypygi;  the  presence  of  CZY  in  Mesothelae  and 
Opisthothelae  is  a synapomorphy  for  them  alone.  The  meaning  of  this  is  that  A.  fimbriunguis 
represents  a clade  of  spiders  forming  the  sister  group  to  Mesothelae  + Opisthothelae,  and  could 
justifiably  be  made  the  single  member  of  a new  suborder. 

There  are  several  interesting  autapomorphies  for  the  Devonian  spider.  Most  obvious  are  the 
fimbriate  claws,  described  above.  These  do  not  occur  on  any  other  spider  known  to  us  and  differ 
strongly  from  the  smooth  claws  of  trigonotarbids.  Secondly,  the  patches  of  acute  spinules  at  the 
inner  base  of  the  palpal  femora  would  appear  to  be  unique  among  spiders.  Somewhat  worrisome, 
but  a potential  third  autapomorphy,  is  the  absence  of  trichobothria.  It  may  be  that  they  are  present 
and  we  have  not  found  them,  but  given  our  close  examination  of  the  material,  this  is  extremely 
unlikely. 

These  additional  observations  have  an  effect  on  the  cladogram  published  by  Shear  et  al.  (1987). 
One  result  has  been  to  affirm  the  basal  position  in  the  cladogram  of  Trigonotarbida  as  the 
plesiomorphic  sister  group  of  all  the  other  included  orders  of  Pulmonata.  The  evidence  lies  in  the 
lack  of  tarsal  organs  and  lyriforms  in  trigonotarbids,  and  the  presence  of  these  features  can  be 
considered  synapomorphic  for  the  other  orders.  (However,  if  the  ‘tarsal  organ’  of  scorpions  and  the 


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Haller’s  Organ  in  ticks  are  homologous  to  the  tarsal  organ  of  spiders,  amblypygids  and  uropygids, 
then  the  loss  of  it  may  be  an  autapomorphy  of  trigonotarbids.)  The  basal,  plesiomorphic  position 
of  the  trigonotarbids,  which  in  general  resemble  ‘spiders  without  spinnerets’,  emphasizes  the 
strongly  derived  nature  of  Amblypygi,  Uropygi,  and  Schizomida. 

Secondly,  the  earlier  conclusion  that  the  Amblypygi  are  the  sister  group  of  Uropygi  + Schizomida, 
and  not  of  Araneae,  is  reinforced.  It  can  be  further  suggested  that  the  key  adaptations  of  the 
ancestor  of  the  ‘pedipalp’  clade  were  the  development  of  raptorial  palps,  probably  articulating  in 
the  horizontal  plane,  antenniform  first  legs  used  as  a ranging  device  for  palpal  strikes,  and  finally, 
as  Manton  (1977)  wrote,  partial  or  total  immobilization  of  the  patella-tibia  joint  to  strengthen  the 
knee,  which  must  undergo  extreme  flexure  in  connection  with  the  other  modifications  of  legs  to 
allow  the  animals  to  slip  sideways  into  narrow  crevices.  In  uropygids,  the  joints  are  far  more  mobile 
on  legs  2-4  than  in  amblypygids,  but  the  patella  -tibia  joint  has  been  entirely  lost  in  the  first  legs. 
Schizomids  may  be  seen  as  a derived  clade  of  uropygids;  the  movement  of  their  palps  in  the  vertical 
plane  and  the  subdivision  of  the  carapace  are  secondary  changes  designed  to  increase  the  flexibility 
of  the  whole  body  to  allow  for  movement  in  the  small  spaces  between  soil  particles.  But  the  fused 
patellotibia  of  the  first  leg  remains  as  a vestige  of  their  common  ancestry  with  uropygids. 

It  should  also  be  recognized  that  naked  cheliceral  fangs,  cheliceral  glands,  transversely  oriented 
metatarsal  lyriforms,  and  the  presence  of  lyriforms  on  podomeres  other  than  metatarsi,  are 
probable  autapomorphies  of  Araneae,  joining  the  better  known  features  of  cheliceral  poison  glands, 
opisthosomal  silk  glands  and  spinnerets,  and  the  palpal  intromittent  organ  in  mature  males. 


SYSTEMATIC  PALAEONTOLOGY 
Order  araneae  Clerck,  1757 

Emended  diagnosis.  Pulmonata  with  paired  abdominal  appendages  modified  as  silk-spinning 
organs;  chelicera  with  cheliceral  gland;  cheliceral  fang  with  poison  gland  opening,  and  without 
setae;  adult  male  palps  modified  for  sperm  transfer;  numerous  longitudinally  oriented  lyriform 
organs  present  on  walking  legs  in  addition  to  transverse  one  on  distal  metatarsus. 

Genus  attercopus  gen.  nov. 

Derivation  of  name.  English  dialect  (from  Old  English)  attercop,  a spider. 

Tvpe  and  only  known  species.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987). 

Diagnosis.  Spider  with  patch  of  minute  cuticular  spinules  on  proximal  infero-?anterior  surface  of 
palpal  femur;  minute  cuticular  fimbriae  on  inferior  surface  of  all  tarsal  claws;  without  longitudinal 
emargination  on  posterior  side  of  distal  edge  of  patella  of  walking  legs. 

Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987) 

Plate  1;  Plate  2,  figs  1,  2,  4-8;  Plate  3;  Plate  4;  Plate  5,  figs  1-3,  5;  Plate  6,  figs  1,  2,  4,  5;  Text-figs  4; 

5a,  b,  d-h;  6;  7;  8;  9a,  c;  10;  12. 

1987  Gelasinotarbus ? fimbriunguis . Shear,  Selden  and  Rolfe;  Shear  et  al.,  pp.  60-65,  71,  figs  128-140. 

1987  Arachnida  Incertae  sedis  B.  Shear,  Selden  and  Rolfe;  Shear  et  al.,  pp.  70,  71,  figs  151-157. 

Type  specimens.  Listed  in  Shear  et  al.  (1987),  p.  60. 

Additional  material.  A complete  list  of  the  specimens  referred  to  this  species  is  deposited  in  the  British  Library, 
Boston  Spa,  Yorkshire,  England,  as  Supplementary  Publication  No.  SUP  14040,  5 pp.;  see  Repository  above 
for  availability  of  this  publication. 


SELDEN  ET  AL.:  DEVONIAN  ARACHNIDS 


257 


Diagnosis.  As  for  the  genus. 

Description 

Cuticle.  The  cuticle  pattern  of  Attercopus  fimbriunguis  is  characteristic,  and  readily  identifiable.  The  surface 
sculpture  was  described  in  Shear  et  al.  (1987,  p.  64)  as  being  reticulate,  with  one  side  (distal,  normally)  of  each 
polygonal  cell  being  thicker  than  the  other  sides;  the  sculpture  of  Incertae  sedis  B was  described  (Shear  et  al. 
1987,  p.  70)  as  being  similar.  This  sculpture  pattern  can  be  confirmed  here,  but  with  added  detail:  first,  the 
distal  side  of  each  polygon  of  the  reticulum  actually  forms  the  proximal  side  of  the  distally  adjacent  cells,  and 
second,  the  sculpture  dissolves  into  smooth  cuticle  in  places,  such  as  over  most  of  the  distal  parts  of  the  tarsus 
and  the  chelicera.  Two  distinct  sizes  of  setal  socket  and  the  presence  of  long,  fine  setae  without  bifid  tips  were 
mentioned  by  Shear  et  al.  ( 1 987) ; the  cuticle  of  Incertae  sedis  B was  described  as  lacking  this  bimodality  of  setal 
sockets.  The  present  study  confirms  that  two  sizes  of  setal  sockets  may  be  present,  for  example,  on  most  of  the 
leg  segments  there  are  small  sockets  with  long,  fine  setae,  and  larger  sockets  bearing  larger,  long  setae.  This 
bimodality  can,  in  fact,  be  seen  on  the  published  figures  of  Incertae  sedis  B (Shear  et  al.  1987,  figs  151-154), 
but  it  is  somewhat  variable,  and  is  not,  alone,  diagnostic  for  the  genus.  Many  of  the  setae  can  be  seen  to  be 
finely  serrate,  and  the  macrosetae  bear  serrae  on  their  convex  surface. 

Most  characteristic  of  Attercopus  fimbriunguis  is  the  presence  of  very  small  cuticular  organs  scattered  across 
the  cuticle  surface  (PI.  1,  fig.  1).  Their  distribution  may  be  quite  dense,  for  example  on  the  spinneret  (Text-figs 
10  and  1 1 a,  b).  At  low  magnification  (up  to  about  x 100),  these  appear  very  much  like  small  setal  sockets:  a 
circle  or  oval  of  dark  cuticle,  about  0-006  mm  in  diameter.  At  higher  magnification,  however,  the  central  pore 
is  revealed  as  a slit,  and  thus  these  organs  are  true  slit  sense  organs.  In  addition,  larger  slit  sensilla  are  found 
at  the  joints.  They  may  occur  singly,  at  the  distal  end  of  the  tarsus  for  example,  in  groups,  such  as  those  adjacent 
to  the  distal  articulations  of  the  femur,  or  in  lyriform  organs,  examples  of  which  can  be  seen  at  the  distal  ends 
of  the  patella,  the  tibia  and  the  metatarsus.  The  distribution  of  the  larger  slits  and  lyriforms  on  the  generalized 
leg  is  shown  in  the  reconstruction  (Text-fig.  2). 

A major  surprise  in  the  present  study  was  to  find  no  evidence  of  trichobothria  on  any  of  the  leg  segments. 
The  report  of  one  on  specimen  411.7.19  (Shear  et  al.  1987,  p.  70)  is  incorrect;  study  of  many  more  specimens 
of  femora  has  shown  that  these  podomeres  are  susceptible  to  the  occurrence  of  circular  dark  patches,  the  origin 
of  which  is  unknown,  but  which  may  be  pre-  or  post-mortem  fungal  or  parasitic  attacks.  That  the  dark  patches 
occur  only  rarely,  and  then  in  different  places  on  the  same  podomere  (e.g.  on  palpal  femora),  is  evidence  that 
they  are  not  a feature  of  A.  fimbriunguis. 

Carapace  and  abdomen.  Three  pieces  of  cuticle  may  represent  parts  of  the  carapace.  2002. 12. 102  is  a sheet  of 
typical  reticulate  A.  fimbriunguis  cuticle,  with  small  slit  organs  scattered  over  the  surface,  which  lacks  setal 
sockets  except  at  one  end  where  large  sockets  occur,  adjacent  to  two  large,  oval  holes;  nearby  are  what  appear 
to  be  the  edges  of  two  further  holes  (PI.  1,  fig.  1 ).  On  one  side  of  the  specimen  is  an  edge  with  a narrow  doublure, 
and  that  part  of  the  specimen  which  is  folded  over  also  has  an  edge  to  it.  The  holes  are  interpreted  as  possible 
eyes,  and  the  edges  as  the  carapace  margin.  The  margin  is  not  scalloped,  as  it  is  in  trigonotarbids.  A similar 
edge,  with  a narrow  doublure,  occurs  on  specimen  329.31.  It  is  noteworthy  that  the  carapace  of  Liphistius  is 
almost  devoid  of  setae  except  around  the  margins,  and  adjacent  to  the  group  of  eyes  (which  are  situated  in  the 
midline  at  the  anterior  edge  of  the  carapace)  some  large  setae  are  present.  Specimen  41 1 . 1 1 . 3 is  a chelicera  of 
A.  fimbriunguis  which  is  superimposed  on  a large  sheet  of  A.  fimbriunguis  cuticle.  The  cuticle  sheet  is  torn  down 
the  centre  and  displaced  so  that  it  is  overlapping;  short  lengths  of  edge  can  be  seen  on  the  sheet,  but  no  eyes 
are  present.  Three  characteristics  suggest  that  this  specimen  belongs  to  the  carapace : first,  the  size  of  the  sheet 
in  comparison  to  the  size  of  the  chelicera,  second,  the  lack  of  podomere  structures,  and  third,  the  features  of 
the  presumed  carapace  fragment  2002 . 12 . 102  mentioned  above  (lack  of  setal  sockets  except  near  the  presumed 
anterior  edge)  also  occur  in  this  specimen. 

Sternum.  The  sternum,  which  consisted  of  a cushion-like  surface  in  life,  occurs  in  the  fossil  as  a rectangular  strip 
of  cuticle,  about  five  times  as  long  as  wide  (not  all  of  it  may  be  preserved),  on  specimen  41  1 . 19.83  (PI.  2, 
fig.  2).  Articulations  are  present  at  the  points  where  the  coxae  meet  the  sternum.  There  are  three  pairs  of  these 
visible  in  the  specimen,  one  side  of  each  pair  adjacent  to  each  of  the  two  coxae  preserved.  The  anterior  end 
does  not  preserve  this  feature,  and  the  posterior  end  is  missing.  If  the  well-preserved  coxa  on  this  specimen 
belongs  to  leg  4 (see  below),  then  the  sternum  is  probably  produced  backward  between  coxae  4. 

Chelicera.  The  chelicera  (PI.  1,  figs  2-8)  is  equant  in  shape.  Specimen  334.  la. 7 is  nearly  complete  and  shows 
proximal  articulations  along  a joint  plane  which  is  nearly  at  right-angles  to  the  tooth  row.  The  articulations 


258 


PALAEONTOLOGY.  VOLUME  34 


eyes?  ar 


text-fig.  4.  Atter copus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987),  explanatory  drawings  for  specimens 
illustrated  on  Plate  1.  a,  2002. 12.102,  anterior  part  of  carapace,  small  slit  sensilla  shown  on  internal  surface 
only,  b,  2002 .12.90,  distal  end  of  chelicera.  c,  445 . 1 a . 7,  whole  chelicera  with  fang,  proximal  joint  edges  shown 
at  left  (near  side  is  partly  detached),  foreign  cuticle  fragment  (X)  lying  behind  specimen,  d,  411 .7.33,  nearly 
complete  chelicera  lacking  fang,  showing  tooth  row  and  cheliceral  gland  (both  on  far  side).  E,  distal  end  of 
chelicera  with  fang,  tooth  row  (distal  end  partly  obscured  by  artefact).  Scale  bar  represents  0.5  mm  for  all 
specimens;  see  materials  and  methods  for  abbreviations  and  conventions. 


EXPLANATION  OF  PLATE  1 

Figs  1-8.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1,  anterior  part  of  carapace  showing  possible 
eyes  and  large  setal  sockets  at  anterior,  also  typical  cuticle  sculpture  and  small  slit  sensilla  elsewhere, 
explanatory  drawing  in  Text-figure  4 a,  2002 . 12 . 102,  x 70.  2,  distal  end  of  chelicera  showing  tooth  row,  fang 
articulations,  and  position  of  cheliceral  gland,  explanatory  drawing  in  Text-figure  4b,  2002. 12.90,  x 107. 
3,  distal  end  of  tooth  row  of  specimen  shown  in  fig.  2,  showing  cheliceral  gland,  2002.12.90,  x215.  4, 
chelicera,  lacking  fang,  showing  general  shape,  tooth  row,  and  position  of  cheliceral  gland,  explanatory 
drawing  in  Text-figure  4 D,  41  1 .7.33,  x 95.  5,  distal  end  of  tooth  row  of  specimen  shown  in  fig.  3,  showing 
cheliceral  gland  at  end  of  tooth  row,  411.7.33,  x 235.  6,  whole  chelicera,  showing  general  shape,  articulation 
of  fang,  and  poison  gland  opening,  foreign  cuticle  fragment  lying  across  part  of  tooth  row,  explanatory 
drawing  in  Text-figure  4c,  334.  \a.l  x 55.  7,  distal  part  of  chelicera  showing  tooth  row,  fang  articulation, 
poison  duct  opening,  and  serrated  ridge  on  fang,  artefact  lying  across  distal  end  of  tooth  row,  explanatory 
drawing  in  Text-figure  4e,  329.22.9,  x 132.  8,  distal  part  of  specimen  shown  in  figure  6,  showing  details  of 
fang  articulation,  poison  gland  opening,  serrate  ridge,  and  tooth  row,  334.  la.  7 x 105. 


PLATE  I 


SELDEN  et  al Attercopus 


260 


PALAEONTOLOGY,  VOLUME  34 


text-fig  5.  For  legend  see  p.  262. 


EXPLANATION  OF  PLATE  2 

Figs  1,  2,  4-8.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1,  femur  in  posterior  aspect,  distal  to 
right,  explanatory  drawing  in  Text-figure  5a,  334.  la. 9,  x 64.  2,  left  coxa  (probably  of  leg  4),  sternum  (top 
to  right),  fragment  of  coxa  ?3,  and  piece  of  marginal  cuticle  of  prosoma,  posterior  aspect,  explanatory 
drawing  in  Text-figure  5b,  411 . 19.83,  x 62.  4,  femur,  posterior  aspect,  distal  to  left,  explanatory  drawing 
in  Text-figure  5d,  334.  la. 6,  x93.  5,  complex  grouping  of  podomeres,  including  chelicera  (dark  mass  on 
right),  palpal  femur,  leg  72  femur,  patella,  tibia,  and  tarsus  (all  on  left),  and  plant  cuticle  and  spores, 
explanatory  drawing  on  Text-figure  5e,  329.69,  x 80.  6,  trochanter,  distal  aspect,  inferior  to  top,  fragment 
of  coxa  attached  at  bottom  left,  explanatory  drawing  in  Text-figure  5f,  411.19.1 02,  x93.  7,  three  coxae 
(two  at  top,  one  at  bottom  left)  and  trochanter  (bottom  right),  explanatory  drawing  in  Text-figure  5h, 
334.  la. 9,  x 66.  8,  coxa,  posterior  aspect,  explanatory  drawing  in  Text-figure  5g,  411 . 19.250,  x 117. 

Fig.  3.  Ecchosis  pulchribothrium  gen.  et.  sp.  nov.  Ventral  part  of  coxa,  posterior  aspect,  explanatory  drawing  in 
Text-figure  5c,  2002.9. 13,  x 1 10. 


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are  arranged  in  such  a way  that  it  is  difficult  to  envisage  this  chelicera  being  anything  other  than  orthognath. 
The  teeth  are  in  a single  row  of  about  8-1 1 teeth  (8  in  small,  1 1 in  large  specimens).  The  smallest  teeth  occur 
near  the  fang  tip,  the  larger  occur  closer  to  the  basal  articulation  of  the  fang,  and  largest  of  all  is  third  or  fourth 
from  the  end  of  the  row  nearest  the  fang  articulation.  There  are  no  subsidiary  teeth,  and  the  teeth  are  not 
greatly  different  in  size,  the  smallest  is  about  half  the  size  of  the  largest.  The  fang  curves  gently  to  a point 
adjacent  to  end  of  tooth  row.  A possible  orifice  for  the  poison  gland  may  be  seen  subterminal  to  the  fang  tip 
on  specimens  334.  la. 7 and  329.22.9  (PI.  1,  figs  7 and  8);  other  specimens  do  not  show  the  fang  tip.  The  inner 
surface  of  the  fang  bears  a ridge  of  fine  serrations  extending  the  length  of  the  tooth  row.  Most  of  the  cuticle 
surface  bears  only  a sparse  scattering  of  setal  sockets;  setae  are  numerous  near  the  teeth,  but  do  not  occur  in 
a comb  or  brush.  The  setae  are  finely  serrate.  There  are  no  setae  on  the  fang.  The  cheliceral  gland  openings 
can  be  seen  on  specimens  2002 .12.90,  329 . 3 1 a . M I , and  4 1 1 . 7 . 33  at  the  end  of  the  tooth  row  near  the  fang 
tip  (PI.  1,  figs  3 and  5).  A few  slit  sensilla  occur  adjacent  to  the  fang  articulations. 

Coxa.  Coxae  are  present  on  a number  of  specimens,  but  commonly  these  bear  numerous  other  podomeres 
compressed  together  (on  PI.  2,  fig.  7 three  coxae  and  a trochanter  occur  together),  so  the  coxal  morphology 
is  better  interpreted  from  the  few  isolated  examples  (e.g.  PI.  2,  figs  2 and  8).  Understanding  the  coxal 
morphology  is  aided  by  study  of  the  coxa  of  Liphistius  in  conjunction  with  the  fossils.  The  coxa  on  specimen 
411.19.83  probably  belongs  to  leg  4,  since  it  occurs  at  the  rear  of  the  sternum  (see  below)  which  appears  to 
have  attachment  points  for  at  least  two,  and  probably  three,  coxae  in  front.  If  this  coxa  is  not  leg  4 then  it  would 
be  leg  3.  Adjacent,  and  anterior  to,  the  main  example  on  this  specimen,  is  a small  portion  of  the  medial  side 
of  the  next  coxa  anterior,  also  attached  to  the  sternum,  with  some  membrane  between  the  two.  The  coxa  is  of 
the  boat-like  form  typical  of  most  arachnids,  although  on  this  specimen  the  ventral  surface  is  mainly  missing. 
The  anterior  dorsal  edge  runs  with  a thickened  line  from  an  attachment  point  with  the  sternum  towards  the 
distal  margin,  but  about  two-thirds  of  the  way  along  towards  the  distal  margin,  it  dips  ventrally;  the  next  part 
up  to  the  distal  edge  is  missing.  The  posterior  dorsal  edge  is  also  thickened  in  a line,  which  runs  horizontally 
for  about  one-third  of  the  way  to  the  distal  edge  then  dips  towards  the  ventral,  for  a distance  of  about  half 
the  length  from  the  sternum  to  the  dip,  and  then  runs  to  the  distal  edge  at  this  lower  elevation.  Specimen 
41 1 . 19.250  (PI.  2,  fig.  8)  is  most  useful  for  reconstructing  the  shape  of  the  podomere.  The  anterior  articulation 
at  the  distal  joint  lies  at  the  end  of  a long  ridge  of  thickened  cuticle  (the  costa  coxalis)  which  extends  in  a 
proximodorsal  direction  towards,  and  closely  approaching,  the  anterior  dorsal  edge.  The  posterior  articulation 
consists  of  a sclerite  which  originates  at  the  posterior  edge  of  the  joint  in  an  anterior  position,  and  runs  dorsally, 
separated  from  the  joint  edge  by  membrane  (see  PI.  2,  fig.  8).  The  morphology  of  the  distal  joint  is  very  similar 
to  that  of  the  Recent  Liphistius.  The  strip  of  cuticle  running  along  the  dorsal  side  of  the  coxae,  the  lateral 
marginal  plate,  and  also  seen  in  Liphistius , can  be  seen  on  411 . 19.83.  On  this  specimen  the  posterior  sclerite 
is  folded  onto  the  anterior  side  of  the  distal  joint. 

Trochanter.  Trochanter  morphology  is  difficult  to  interpret  because  so  many  of  the  few  specimens  are  folded 
together  with  coxae  or  femora.  The  best  specimens  are  334.  la. 9 (PI.  2,  fig.  7),  which  is  attached  to  coxae,  but 
relatively  easy  to  make  out,  and  411.19. 102  (PI.  2,  fig.  6),  a separate  trochanter.  The  trochanter  is  a short 
podomere,  the  inferior  surface  is  nearly  twice  as  long  as  the  superior  and  was  bulbous  in  life.  The  interior 
surface  bears  numerous  large  setal  sockets.  Proximal  articulations  consist  of  a prominent,  thick  triangular 
projection  which  marks  the  anterior  articulation,  slightly  inferior  in  position;  the  posterior  articulation  shows 


text-fig.  5.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987)  (a,  b,  d-h)  and  Ecchosis  pulchribothrium 
gen.  et  sp.  nov.  (c),  explanatory  drawings  for  specimens  illustrated  on  Plate  2.  a,  334.  la.  9,  femur  of  walking 
leg,  posterior  aspect,  b,  41 1 . 19.83,  left  coxa  (of  leg  4?),  sternum,  fragment  of  next  anterior  coxa,  and  piece  of 
marginal  prosomal  cuticle  (folded  and  twisted),  ventral  surface  of  coxa  ?4  absent,  c,  2002.9. 13,  ventral  part 
of  coxa  of  Ecchosis , ventral  surface  to  lower  right,  distal  joint  to  left  (superior  side  absent),  spore  in  black. 
D,  334.  la. 6,  femur  of  walking  leg,  posterior  aspect,  e,  329.69,  complex  group  of  podomeres  (setae  omitted), 
plant  cuticle,  spores  (in  black).  F,  411.19.102,  trochanter,  distal  aspect,  inferior  to  top,  posterior  to  left, 
including  fragment  of  coxa  (shaded)  with  posterior  articulation.  G,  41 1 . 19.250,  ventral  half  of  coxa,  torn  and 
folded,  posterior  aspect,  inferior  to  lower  right,  distal  joint  to  left  (superior  side  absent),  setae  omitted. 
h,  334.  la. 9,  three  coxae  and  trochanter,  two  coxae  at  top,  one  at  lower  left,  trochanter  at  lower  right,  setae 
and  interior  surfaces  of  upper  two  coxae  omitted.  Scale  bar  represents  0.5  mm  for  all  specimens;  see  material 

and  methods  for  abbreviations  and  conventions. 


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263 


only  as  a darkened  edge,  the  major  part  of  this  being  on  the  coxal  side  of  the  joint.  However,  411.19.102 
(PI.  2,  fig.  6)  shows  a portion  of  the  coxa  attached  at  this  point,  and  reveals  the  detail  of  the  articulation  well.  The 
distal  joint  bears  anterior  and  posterior  articulations;  these  are  not  well  expressed,  being  only  dark  but  discrete 
edges  to  the  podomere.  They  are  connected  by  a fold  of  cuticle  on  the  inferior  edge  which  marks  the  distal 
termination  of  the  bulbous  part  of  the  inferior  surface.  Superoanteriorly  on  the  distal  edge  there  is  a group  of 
slit  sensilla;  a group  of  slit  sensilla  occurs  in  exactly  the  same  position  in  Liphistius,  and  is  useful  for  identifying 
the  orientation  of  loose  podomeres.  Specimen  329.59,  which  was  figured  by  Shear  et  al.  (1987,  fig.  140)  as  a 
possible  median  organ  of  some  kind,  is  now  reinterpreted  as  half  of  a trochanter.  The  cuculliform  shape 
described  by  Shear  et  al.  (1987,  p.  64),  is  incorrect,  since  there  is  only  a single  layer  of  cuticle  present,  the 
inferior  surface  of  the  trochanter,  and  basally,  the  two  proximal  articulations  can  be  seen. 

Femur.  The  femur  is  an  easily  recognizable  podomere,  and  occurs  on  many  slides.  The  characteristic  palpal 
femur,  with  a patch  of  spinules,  is  described  below.  The  femur  is  a long  podomere,  with  a bicondylar  horizontal 
pivot  joint  proximally  (PI.  3,  fig.  8)  and  a greatly  inferiorly  emarginated  distal  joint  with  a dorsal  bicondylar 
hinge.  Specimens  334.  In. 6,  334.  In. 9,  2002.12.79,  and  329.3  (PI.  2,  figs  1 and  4;  PI.  3,  figs  1 and  2)  show 
typical  podomeres.  Longitudinal  rows  of  setal  sockets  occur  on  the  superior  surface,  and  similar  rows  are  found 
on  the  inferior  surface.  The  anterior  and  posterior  sides  are  devoid  of  setae.  The  articulations  on  the  proximal 
joint  occur  on  pronounced  promontories.  The  distal  joint  bears  curved  rows  of  slit  sensilla  adjacent  to  the 
articulations,  which  are  situated  superoposteriorly  and  superoanteriorly.  Fewer  slits  occur  in  the  anterior 
group  than  in  the  posterior.  Some  variation  in  the  femora  is  noticeable,  in  greater  or  lesser  amounts  of 
emargination  at  the  inferior  side  of  the  distal  joint.  This  can  be  accounted  for  by  differences  between  the  legs. 
In  Liphistius , the  emargination  is  greatest  on  legs  2 and  3,  whereas  on  leg  4 and  on  the  palp  there  is  less 
emargination;  the  least  emargination  of  all  occurs  on  leg  1.  The  amount  of  emargination  is  correlated  with  the 
degree  of  flexure  required  during  stepping  of  the  legs,  and  the  activities  of  the  palp.  Specimen  329. 3 la.  Ml  (PI. 
3,  fig.  7)  shows  a femur  with  little  emargination  in  connection  with  a chelicera  and  palpal  femora;  this 
presumably  belongs  to  leg  1 . 

The  palpal  femur  is  not  very  large  (the  largest  is  specimen  329.63,  figured  in  Shear  et  al.  1987,  fig.  155),  and 
bears  a patch  of  cuticular  spinules  on  its  proximal  infero-?anterior  surface  (PI.  3,  fig.  4).  The  spinules  are  not 
setae,  but  cuticular  projections,  and  were  figured  by  Shear  et  al.  (1987,  figs  156  and  1 57).  By  assuming  that  these 
were  used  towards  the  mouth  or  towards  the  anterior/mesal,  then  they  would  be  on  the  inner,  proximal 
prolateral  side.  The  bases  for  the  supposition  that  this  podomere  is  palpal  are,  first,  that  modifications  to  the 
prosomal  limbs  in  spiders  are  more  likely  to  affect  the  palp  than  any  other  leg,  and  second,  that  when  this 
podomere  is  found  connected  together  with  other  organs,  it  is  found  adjacent  to  the  chelicera  in  all  cases.  Apart 
from  the  patch  of  spinules,  the  palpal  femur  is  similar  to  the  other  femora.  There  is  a bicondylar  pivot  joint 
with  a horizontal  axis  at  the  proximal  end  of  the  podomere,  and  a superior  bicondylar  hinge  distally,  with  a 
greatly  emarginated  inferior  surface.  Rows  of  slit  sensilla  occur  adjacent  to  the  distal  articulations.  Setae  on 
the  podomere  occur  in  rows;  principally  two  rows  superiorly,  two  inferiorly,  and  one  retrolaterally.  Specimens 
329.3  (PI.  3,  fig.  2)  and  329.63  show  right  femora,  and  329. 1 (PI.  3,  fig.  4)  shows  the  left  femur  in  connection 
with  the  patella.  Two  palpal  femora  are  present  on  329. 31a. Ml,  together  with  the  chelicera,  and  other 
podomeres. 

Patella.  The  patella  is  a short  podomere,  with  the  curved  superior  surface  more  than  twice  the  length  of  the 
inferior  surface.  Specimens  are  shown  on  Plate  3,  figures  3-7,  and  Plate  4,  figures  2 and  5.  The  proximal  joint 
bears  supcroanterior  and  superoposterior  articulations  corresponding  to  those  distally  on  the  femur.  The 
inferior  part  of  this  joint,  however,  is  emarginated,  more  so  posteriorly  than  anteriorly,  and  two  dark,  recurved 
areas  are  present  in  inferoposterior  and  inferoanterior  positions.  By  comparison  with  living  spiders, 
amblypygids,  and  uropygids,  these  areas  mark  the  sites  of  suspension  of  the  arcuate  sclerite:  a distally 
procurved  sclerite  lying  in  the  membrane  of  the  greatly  emarginated  Fe-Pa  joint,  and  facilitating  flexion  from 
the  extreme  extension  possible  at  this  joint.  The  sclerite  itself  seems  unlikely  to  be  preserved,  but  nevertheless, 
one  appears  to  be  present  on  specimen  329. 31a.  Ml,  on  leg  ?1  (PI.  3,  fig.  7).  Distally,  there  is  a strong 
superior  articulation;  the  distal  joint  is  not  a bicondylar  pivot,  as  stated  by  Shear  et  al.  (1987,  p.  63), 
but  is  monocondylar.  Three  lyriform  organs  are  situated  in  an  inferoposterior  position,  and  two  occur 
inferoanteriorly,  on  the  distal  joint.  Of  especial  interest  here,  is  the  lack  of  a pronounced  emargination  (CZY) 
on  the  posterior  side  of  the  distal  joint,  seen  in  Liphistius  and  all  other  spiders.  In  this  respect,  the  A. 
fimbriunguis  patella  more  closely  resembles  that  of  the  ambulatory  legs  of  uropygids.  The  superior  surface  bears 
about  four  large  setae  in  addition  to  the  smaller  ones.  Smaller  setae  occur  elsewhere,  especially 
superoproximally  and  inferiorly. 


264 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  6.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987),  explanatory  drawings  for  specimens 
illustrated  on  Plate  3.  a,  2002. 12.79,  posterior  aspect  of  right  walking  leg  femur,  spores  omitted,  b,  329.3, 
anterior  aspect  of  right  palpal  femur,  spore  omitted,  c,  329.59,  distal  end  of  left  femur  and  attached  patella, 
posterior  aspect,  d,  329.1,  posterior  aspect  of  left  palpal  femur  and  attached  patella,  spores  omitted,  e, 
329 . 3 1 a . M 1 , detail  of  joints  of  left  femur  and  patella,  including,  sclerite,  posterior  aspect,  f,  334 . 1 6 . 86,  femur 
and  patella,  foreign  cuticle  omitted.  G,  334. 1 6.  12,  distal  femur  and  patella.  Scale  bar  represents  0.5  mm  for 
all  specimens;  see  material  and  methods  for  abbreviations  and  conventions. 


EXPLANATION  OF  PLATE  3 

Figs  1-8.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1,  femur,  posterior  aspect,  distal  to  right, 
circular  spores  attached,  explanatory  drawing  in  Text-figure  6a,  2002. 12.79,  x 84.  2,  right  palpal  femur, 
anterior  aspect,  distal  to  right,  patch  of  spinules  on  near  (anterior)  surface,  black  spore  attached,  explanatory 
drawing  in  Text-figure  6b,  329.3,  x 133.  3,  distal  end  of  femur,  patella,  posterior  aspect,  explanatory 
drawing  in  Text-figure  6 c,  329. 59,  x 73.  4,  left  palpal  femur  and  patella,  patch  of  spinules  on  far  (anterior) 
surface,  dark  spores  attached,  explanatory  drawing  in  Text-figure  6d,  329 . 1 , x 74.  5,  distal  end  of  femur  and 
patella,  explanatory  drawing  in  Text-figure  6g,  334.16.  12,  x 115.  6,  femur  and  patella,  foreign  cuticle 
fragment  overlying  proximal  part  of  femur,  explanatory  drawing  in  Text-figure  6f,  334.  16.86,  x 71.  7,  part 
of  complex  grouping  of  podomeres  showing  distal  femur  and  patella,  posterior  aspect,  distal  to  left,  details 
including  sclerite  at  proximal  joint  of  patella,  distal  patella  with  attached  fragment  of  tibia,  explanatory 
drawing  in  Text-figure  6e,  329. 31  a.  Ml,  x 68.  8,  proximal  end  of  femur  showing  large  setal  sockets, 
41 1 . 19.243,  x 60. ^ 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  7.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987),  explanatory  drawings  for  specimens 
illustrated  on  Plate  4.  a.  329.3,  distal  end  of  tibia,  detritus  shown  at  X,  setal  sockets  not  differentiated 
according  to  surface  and  setae  omitted.  B,  41 1 . 7.45,  distal  end  of  tibia,  inferior  aspect,  spore  shown  in  black, 
c,  41 1 .20.25,  patella,  inferior  aspect,  spore  shown  in  black,  detritus  by  X.  d,  411 . 19.248,  distal  aspect  of 
patella,  focused  to  show  details  of  distal  joint,  superior  to  left,  e,  334.  la. 8,  tibia,  setae  omitted,  f,  4 1 1 . 19.98, 
distal  end  of  tibia  and  proximal  piece  of  metatarsus,  superior  aspect,  setae  and  sockets  omitted.  G,  329.3, 
metatarsus,  proximal  end  to  left,  distal  to  right,  superolateral  aspect,  setal  sockets  omitted.  Scale  bar  represents 
0.5  mm  for  all  specimens;  see  material  and  methods  for  abbreviations  and  conventions. 


EXPLANATION  OF  PLATE  4 

Figs  I -1 1 . Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1 , distal  end  of  tibia,  dark  mass  of  detritus, 
explanatory  drawing  in  Text-figure  7 a,  329 . 3,  x 70.  2,  patella,  inferior  aspect,  distal  to  left,  pieces  of  detritus 
on  right,  and  spore,  explanatory  drawing  in  Text-figure  7 b,  41 1 .20.25,  x 132.  3,  distal  end  of  tibia,  showing 
sensilla  and  articulations,  spore  in  top  left,  explanatory  drawing  in  Text-figure  7c,  41 1 .7.45,  x 125.  4,  distal 
end  of  tibia  showing  sensilla,  2002. 12.49,  x 65.  5,  patella,  details  of  distal  joint,  explanatory  drawing  in 
Text-figure  7d.  41 1 . 19.248,  x 190.  6,  tibia,  distal  to  right,  explanatory  drawing  in  Text-figure  7e,  334.  la. 8, 
x 66.  7,  distal  end  of  tibia  attached  to  proximal  part  of  metatarsus,  superior  aspect,  explanatory  drawing  in 
Text-figure  7 g,  411.19. 98,  x 124.  8,  metatarsus,  distal  to  left,  attached  spore  at  top,  329.38,  x 58.  9, 
metatarsus,  distal  to  left,  329.53,  x 53.  10,  metarsus,  broken  into  two  parts,  distal  to  right,  superolateral 
aspect,  explanatory  drawing  in  Text-figure  7f,  329.3,  x46.  11.  metatarsus,  superolateral  aspect,  distal  to 
left,  41  I . 19.251,  x 92. 


PLATE  4 


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268 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  8.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987)  (a-d)  and  Arachnida  incertae  sedis  (b), 
explanatory  drawings  for  Plate  5.  a-c,  334.  la. 4,  two  walking  legs,  patella  to  tarsus;  a,  detail  of  distal  end  of 
tarsus,  setae,  sockets,  and  slit  sensilla  omitted ; b,  complete  specimen  with  adjacent  Arachnida  incertae  sedis 
flagelliform  appendage,  setae  and  sockets  omitted  for  clarity;  c,  detail  of  metatarsus-tarsus  joint,  distal  to  top, 
setae  and  sockets  omitted,  arthrodial  membrane  shown  in  coarse  stipple.  D,  334. 16.38,  tarsus,  showing  tarsal 
organ  and  slit  sensilla,  setae  omitted,  spore  at  proximal  end.  Scale  bar  represents  0.25  mm  for  a and  c,  1.5  mm 
for  b,  and  0.5  mm  for  d;  see  material  and  methods  for  abbreviations  and  conventions. 


Tibia.  This  podomere  is  about  three  times  as  long  as  wide  (PI.  4,  fig.  6).  When  flattened  in  the  fossils,  it  appears 
rectangular,  lacking  the  distal  emargination  and  the  proximal  promontories  of  the  femur.  It  can  be 
distinguished  from  the  metatarsus  by  the  superodistal  lyriform  organ  of  the  latter,  which  has  the  slit  sensilla 
arranged  transversely.  The  proximal  joint  of  the  tibia  bears  a strong  superior  articulation.  The  distal  joint  is 
a superior  bicondylar  hinge.  Adjacent  to  one  side  of  the  distal  articulations  is  a row  of  slit  sensilla,  and  there 
are  lyriforms  situated  close  to  the  inferior  on  this  side,  and  on  the  opposite  side  of  the  joint  in  an 
anterior/posterior  position.  Features  of  the  distal  joint  are  shown  on  Plate  4,  figs  1,  3,  4,  9.  It  is  not  possible 
to  orient  the  tibia  since  the  only  specimens  which  are  in  direct  connection  with  the  patella  and  also  preserve 
the  distal  joint  are  obscured  by  other  podomeres. 

Metatarsus.  The  metatarsus  is  the  longest  podomere  on  the  leg,  the  longest  being  nearly  four  times  as  long  as 
wide,  in  the  flattened  state.  The  proximal  joint  is  a superior  bicondylar  hinge  (see  tibia,  above).  The  distal  joint 


explanation  of  plate  5 

Figs  1-3,  5.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1,  detail  of  distal  end  of  tarsus  shown  in 
upper  part  of  fig.  3,  showing  setation,  serrate  macroseta  inferiorly,  tarsal  organ  superiorly,  and  arrangement 
of  paired  and  median  fimbriate  claws,  explanatory  drawing  in  Text-figure  8a,  334.  la. 4,  x 165.  2,  tarsus, 
distal  to  top,  329.16.34,  x92.  3,  complex  grouping  of  two  walking  legs  of  Attercopus  with  adjacent 
flagelliform  appendate  of  Arachnida  incertae  sedis,  explanatory  drawing  in  Text-figure  8b,  334.  la.  4,  x 94. 
5,  tarsus,  distal  to  left,  showing  tarsal  organ,  claws,  spore  at  proximal  end,  explanatory  drawing  in  Text- 
figure  8 d,  334. 16.38,  x 76. 

Figs  3 and  4.  Arachnida  incertae  sedis.  3 flagelliform  appendage  with  12  segments  (including  distal?),  showing 
setae  and  slit  sensilla,  adjacent  to  legs  of  Attercopus , explanatory  drawing  in  Text-figure  8b,  334.  la.  4,  x 94. 
4,  8-segmented  flagelliform  appendage  (including  distal?),  showing  setae  and  slit  sensilla,  2002.9.20,  x 80. 


PLATE  5 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  9.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987)  (a,  d)  and  Ecchosis  pulchribothrium  gen. 
el.  sp.  nov.  (b.  c),  explanatory  drawings  for  Plate  6.  a,  41  1 .02.  I2M.6,  metarsus  and  overlying  tarsus,  setal 
sockets  not  differentiated  according  to  surface  and  setae  ommited.  b,  411.7.37,  patella  and  proximal  end  of 
tibia,  inferior  aspect,  distal  to  top.  c,  41 1 . 19 . 96,  patella,  superior  aspect,  distal  to  left,  d,  329 . 69,  palpal  tarsus, 
setal  sockets  not  differentiated  according  to  surface  and  setae  omitted.  Scale  bar  represents  0.5  mm  for  all 
specimens;  see  material  and  methods  for  abbreviations  and  conventions. 


is  readily  recognized  by  the  large  lyriform  organ  situated  in  a superior  position,  which  characteristically  has  the 
slits  arranged  at  right  angles  to  the  long  axis  of  the  leg.  The  lyriform  is  situated  at  the  base  of  a cuticular 
projection  which  bears  articulations  at  either  side  (PI.  4,  figs  8-1 1 ; PI.  5,  fig.  3 ; PI.  6,  fig.  1 ).  Though  resembling 
a bicondylar  hinge,  the  arrangement  here  is  actually  a rocking  joint.  As  in  spiders,  the  two  ‘condyles’  are 
projections  which  articulate  with  the  tarsus  only  loosely,  the  joint  being  held  by  muscles,  and  the  joint  allows 
rocking  in  an  antero-posterior  direction  as  well  as  flexure,  as  necessary  (see  Manton  1977 ; Clarke  1984,  1986). 
The  metatarsus  is  well  clothed  with  setae,  some  of  which  are  long  and  thin,  and  macrosetae  are  present 


EXPLANATION  OF  PLATE  6 

Figs  1,  2,  4,  5.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  1,  metatarsus  and  overlying  tarsus, 
distal  to  left,  explanatory  drawing  in  Text-figure  9 a,  411 . 02.12M.6,  x 60.  2,  detail  of  distal  end  of  tarsus 
shown  in  fig.  1,  showing  claw  fimbriae  and  tarsal  organ,  explanatory  drawing  in  Text-figure  9a, 
411.02. 12M  .6,  x 154.  4,  complex  grouping  of  walking  leg  podomeres,  including  tibiae,  metatarsi,  and  tarsi, 
showing  setae,  claws,  and  tarsal  organs,  329. 3 In.  M2,  x 98.  5,  palpal  tarsus,  showing  attachment  to 
metatarsus  fragment,  setae,  and  single  fimbriate  claw,  explanatory  drawing  in  Text-figure  9d,  329.69,  x 80. 

Figs  3 and  6.  Ecchosis  pulchribothrium  gen.  et  sp.  nov.  3,  patella,  superior  aspect,  distal  to  left,  explanatory 
drawing  in  Text-figure  9c,  41 1.19.96,  x 65.  6,  patella  and  proximal  end  of  tibia,  inferior  aspect,  distal  to 
top,  explanatory  drawing  in  Text-figure  9b,  411  .7.37,  x90. 


PLATE  6 


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PALAEONTOLOGY,  VOLUM  E 34 


text-fig.  10.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987),  explanatory  drawing  for  Text-figure  1 1, 
posterior  median  spinneret,  distal  to  right,  specimen  is  folded  into  three  layers  at  thickest,  small  slit  sensilla 
shown  on  near  surfaces,  setal  sockets  on  far  surfaces  shown  in  dotted  lines  for  clarity.  Scale  bar  represents 
0.5  mm;  see  material  and  methods  for  abbreviations  and  conventions. 


interiorly  and  inferodistally.  The  macrosetae  are  very  prominent,  see,  for  example,  Plate  5,  figure  3,  and  Shear 
et  al.  (1987,  figs  132  and  133).  A few  slits  are  present  inferoanteriorly  and  inferoposteriorly  around  the  joint 
margin,  adjacent  to  the  macrosetae.  No  trichobothria  have  been  seen  on  this  podomere. 

Tarsus.  The  tarsus  (PI.  5,  figs  1-3,  5;  PI.  6,  figs  1,  2,  4,  5)  is  about  five-sixths  the  length  of  the  metatarsus,  and 
is  similarly  profusely  clothed  with  two  sizes  of  setae,  and  macrosetae  occur  inferiorly.  Except  proximally  in 
larger  specimens,  the  reticulate  pattern  characteristic  of  this  genus  is  absent.  The  proximal  joint  bears  two 
articulations  which  correspond  to  the  articulations  on  the  metatarsus.  The  leg  tarsi  are  parallel-sided,  and  the 
distal  joint  bears  three  emarginations,  in  inferior,  anterior,  and  posterior  positions.  Pairs  of  slit  sensilla  occur 
adjacent  to  the  anterior  and  posterior  embayments.  There  are  three  claws  on  the  leg  tarsi : the  lateral  claws  are 
long  and  curved,  the  median  claw  is  also  quite  long,  and  is  thicker  in  mid-section  and  shorter  than  the  lateral 
claws.  All  claws  bear  rows  of  fimbriae  along  their  inferior  edges  (PI.  5,  fig.  1 ; Shear  et  al.  1987,  figs  137-139). 
Trichobothria  cannot  be  seen  on  any  of  the  fossil  specimens.  A tarsal  organ  is  present  in  a superodistal  position 
(PI.  5,  fig.  1 ; PI.  6,  figs  2 and  4). 

The  palpal  tarsus  (PI.  6,  fig.  5;  Shear  et  al.  1987,  fig.  135)  is  not  parallel-sided,  but  tapers  distally  and  is  also 
distinguished  by  the  presence  of  only  a single  fimbriate  claw. 

Spinneret.  The  single  spinneret  (specimen  334.  lb. 34;  Text-figs  10  and  11a-c),  believed  for  reasons  already 
discussed  (Shear,  Palmer  et  al.  1989)  to  be  a posterior  median  spinneret,  is  about  0-94  mm  long  and  represents 
a nearly  complete  single  article  of  typical  semifusiform  shape.  The  specimen  appears  to  have  been  torn  along 
the  median  surface,  and  subsequently  the  torn  edge  (now  nearest  the  observer  as  the  spinneret  is  mounted  on 
a microscope  slide)  was  folded  under  itself.  The  cuticle  is  typical  of  A.  fimbriunguis,  ornamented  with  distinct 
polygonal  cells,  setal  sockets  and  slit  sense  organs,  the  latter  two  structures  densely  but  evenly  scattered  over 
the  entire  surface.  Some  of  the  sockets  bear  large,  smooth  setae,  and  a single  serrate  seta  is  present  (Text-fig.  10). 
Spigots  are  scattered  along  the  median  surface  only,  and  more  densely  clustered  distally.  Though  folding  and 
consequent  superposition  of  structures  makes  an  exact  count  difficult,  at  least  24  distinct  individual  spigots  can 
be  seen.  There  appears  to  be  no  significant  variation  in  spigot  size  and  form.  Each  spigot  consists  of  a conical 


SELDEN  ET  AL.  DEVONIAN  ARACHNIDS 


273 


text-fig.  11.  Attercopus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987).  a-c,  334 . 1 ^ . 34.  a,  posterior  median 
spinneret,  distal  to  right,  explanatory  drawing  in  Text-figure  10,  x 70.  b,  detail  of  base  of  lowermost,  distally- 
directed,  terminal  spigot  shown  in  a and  c,  with  ?setal  socket,  distal  to  top,  x 1200.  c,  distal  end  of  spinneret 

showing  detail  of  cuticle  and  spigots,  x 130. 


base  approximately  twice  as  long  as  wide,  which  narrows  abruptly  to  a slender  shaft  no  more  than  three  times 
as  long  as  the  base.  What  appears  to  be  a large  setal  socket  is  found  on  some  of  the  spigot  bases;  the  consistent 
position  of  this  structure  and  careful  focussing  confirms  that  it  is  on  the  spigot  base  and  is  not  a feature  of 
overlying  or  underlying  spinneret  cuticle.  The  articulation  of  the  base  with  the  shaft  is  smooth,  lacking  a collar. 
No  sculpturing  is  detectable  on  the  distal  part  of  the  shaft,  but  extraordinarily  fine  sculpture,  as  is  found  on 
the  shafts  of  some  rastelloid  mygalomorph  spiders  (J.  Palmer,  pers.  comm.),  may  have  been  obliterated  during 
diagenesis. 


Subclass  pulmonata  ( sensu  Firstman  1973)  incertae  sedis 
Genus  ecchosis  gen.  nov. 

Derivation  of  name.  Greek,  ec -,  out  of,  from,  and  chosis , a heaping-up  of  earth;  referring  to  the  earth-dam  for 
the  pump-storage  power  station  which  now  covers  the  Gilboa  locality. 

Type  and  only  known  species.  Ecchosis  pulchribothrium  sp.  nov. 

Diagnosis.  Pulmonate  with  patellar  trichobothrium,  the  basal  collar  of  which  is  ornamented  with 
reticulate  pattern  of  oval  and  lunate  reticulate  thickenings;  thick,  striated  spines  with  bifid  tips  on 
some  other  podomeres. 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  12.  Alter  copus  fimbriunguis  (Shear,  Selden  and  Rolfe,  1987),  explanatory  drawings  for  specimens 
illustrated  in  Shear  et  al.  (1987).  a,  329. 70,  left  walking  leg  femur  and  patella,  anterior  aspect,  see  Shear  et  al. 
(1987,  tig.  129).  b,  329.39,  patella,  inferior  aspect,  distal  to  right,  see  Shear  et  al.  (1987,  fig.  128).  c,  329.59, 
trochanter,  inferior  aspect,  distal  to  top,  superior  surface  absent,  specimen  previously  described  and  illustrated 
in  Shear  et  al.  (1987,  fig.  140)  as  'undetermined  median  structure’,  d,  329.70,  distal  end  of  metatarsus  and 
proximal  tarsus,  distal  to  right,  setal  sockets  not  differentiated  according  to  surface  and  setae  omitted  from 
tarsus,  see  Shear  et  al.  (1987,  fig.  132).  e,  329.70,  distal  end  of  metatarsus  showing  slit  sensilla  and  serrate 
macrosetae,  distal  to  left,  setal  sockets  not  differentiated  according  to  surface,  spores  in  black,  see  Shear  et  al. 
(1987,  fig.  133).  f,  329.57,  distal  part  of  metatarsus,  distal  to  left,  setae  (except  macrosetae)  omitted,  see  Shear 
et  al.  (1987,  fig.  131).  Scale  bar  represents  0-5  mm  for  all  specimens;  see  material  and  methods  for 

abbreviations  and  conventions. 


SELDEN  ET  A L. : DEVONIAN  ARACHNIDS 


275 


Ecchosis  pulchribothrium  sp.  nov. 

Plate  2,  fig.  3;  Plate  6,  figs  3 and  6;  Plate  7,  figs  1,  3,  4,  7,  8;  Text-figs  5 c and  9 b,  c. 

1987  Arachnida  incertae  sedis  A,  Shear,  Selden  and  Rolfe;  Shear  et  al. , pp.  70,  71,  figs  146-150. 
Derivation  of  name.  Latin,  pulcher , beauty,  and  bothrium , a cup. 

Type  specimens.  Holotype : patella  and  base  of  tibia,  on  slide  411.7.37.  Paratypes : patella?  on  slide  411.7.86; 
distal  end  of  femur,  on  slide  411.1.33;  two  parts  of  unknown  podomere  with  large  sockets  and  striated  spines, 
on  slide  411 . 19.188. 

Additional  material.  A complete  list  of  the  specimens  referred  to  this  species  is  deposited  in  the  British  Library, 
Boston  Spa,  Yorkshire,  England,  as  Supplementary  Publication  No.  SUP  14040,  5 pp.;  see  Repository  above 
for  availability  of  this  publication. 

Diagnosis.  As  for  the  genus. 

Description 

Cuticle.  Large  sheets  of  cuticle  (PI.  7,  figs  1 and  7)  of  this  animal  occur  in  the  Gilboa  material,  and  are 
characterized  by  an  ornament  of  small  scales,  resembling  a reticulate  ornament,  thickened  at  one  side,  in  which 
the  connections  between  the  thickenings  have  been  lost.  The  scales  are  arranged  in  straight  or  arcuate  parallel 
rows;  the  arcuate  patterned  cuticle  is  presumed  to  represent  podomeres  which  have  become  opened  out.  The 
cuticle  bears  setal  sockets  whose  diameters  range  in  size  from  small  (0015  mm)  to  extremely  large  (045  mm), 
and  additionally  there  are  small  (0-005  mm),  circular  pores  scattered  across  the  cuticle.  The  largest  sockets  only 
occur  on  one  type  of  podomere.  On  what  is  presumed  to  be  body  cuticle,  the  setal  sockets  range  up  to  0 075  mm 
in  diameter,  and  these  larger  ones  commonly  have  a raised  rim  or  broad  spine  on  one  side  of  the  socket.  This 
pattern  is  particularly  emphasized  on  what  are  presumed  to  be  edges  of  tergites,  where  a large  thorn  has  a small 
spine  articulated  at  its  base;  such  an  arrangement  appears  to  be  common  on  the  cuticle  of  amblypygids.  Large 
slit  sensilla  are  also  present  on  these  pieces.  The  macrosetae  are  conspicuously  striated,  and  the  very  large,  thick 
spines  are  not  only  striated  but  also  have  bifid  tips,  a feature  lacking  on  smaller  setae  (PI.  7,  figs  4 and  8).  The 
cuticle  of  Ecchosis  resembles  that  of  Liphistius  in  the  following  features:  scale-like  sculpture,  minute  pores  on 
cuticle  surface,  raised  rim  to  larger  setal  sockets,  and  striations  on  macrosetae. 

Coxa.  The  inferior  surface  and  distal  joint  of  the  coxa  is  preserved  on  slide  2002.9. 13  (PI.  2,  fig.  3).  The  costa 
coxalis  can  be  seen  to  run  as  a thickened  ridge  towards  the  anterior  dorsal  edge  of  the  podomere  (which  is  not 
preserved).  Close  to  the  preserved  proximal  termination  of  the  costa  coxalis,  and  running  at  an  angle  from  it 
towards  the  distal  edge,  is  a folded  piece  of  cuticle  which  is  believed  to  represent  the  stiffened  cuticle  by  which 
the  coxa  articulates  dorsodistally  with  the  body  wall,  in  comparison  with  the  coxa  of  Liphistius.  The  posterior 
and  superior  margins  of  the  distal  joint  are  folded  across  the  anterior  surface  and  the  costa  coxalis.  The  ventral 
surface  is  covered  with  setal  sockets  and  richly  supplied  with  pores;  the  inferoanterior  surface  bears  fine  setae. 
There  is  a fragment  of  the  dorsal  edge  preserved  at  the  proximal  end  of  the  podomere.  No  other  specimen  of 
this  podomere  is  known. 

Femur.  A large  femur  is  present  on  slide  41 1 . 1 . 33  (PI.  7.  fig.  1 ).  Only  the  distal  half  is  preserved,  including  parts 
of  the  distal  joint:  one  of  the  articulations,  a small  group  of  slit  sensilla  adjacent  and  just  superior  to  the 
articulation,  and  the  emarginated  inferior  border.  A number  of  small  setal  sockets  are  present,  and  two 
longitudinal  rows  of  three  or  four  larger  sockets  run  along  the  inferior  side  of  the  podomere. 

Patella.  One  definite  patella  is  present,  on  slide  411.7.37  (PI.  6,  fig.  6),  attached  to  the  proximal  end  of  a tibia. 
The  patella  is  easily  recognized  by  its  emarginated  inferior  proximal  edge,  which  bears  inferoanterior  and 
inferoposterior  crescentic  articulation  points,  for  attachment  of  the  arcuate  sclerite  (not  preserved).  The 
superior  edge  of  the  proximal  joint  is  not  preserved.  The  superior  surface  of  the  patella  is  twice  the  length  of 
the  inferior  surface;  it  bears  four  or  five  setal  sockets,  some  with  setae,  and  a short  distance  proximal  to  the 
superior  articulation  of  the  distal  edge  lies  an  ornamented  trichobothrial  base.  Three  small  slit  sensilla  occur 
between  this  bothrium  and  the  articulation  point,  which  is  present  at  the  extremity  of  the  distally  produced 
superior  side  of  the  distal  joint.  The  inferior  side  of  the  distal  joint  is  fairly  straight,  and  is  characterized  by 


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PALAEONTOLOGY,  VOLUME  34 


two  groups  of  large  slit  sensilla,  the  slits  at  an  angle  distally  diverging  from  the  midline,  and  an  interiorly 
positioned  single  large  slit  which  runs  at  an  angle  of  about  80°  from  the  others  (this  slit  may  be  part  of  another 
group,  but  dark  material  obscures  the  podomere  at  this  point).  The  presence  of  an  inferior  articulation  at  the 
distal  joint  is  suspected,  but  not  clearly  seen  because  of  the  obscuring  dark  matter,  because  there  is  an 
articulation  on  the  corresponding  inferior  side  of  the  piece  of  tibia  which  is  inserted  into  the  patella  (PI.  6, 
fig.  6). 

Two  other  podomeres  bear  an  ornamented  trichobothrial  base.  The  best  preserved  specimen  is  411.7.86 
(Shear  et  al.  1987,  figs  149  and  150).  The  bothrium  consists  of  a ring  of  thickened  cuticle  surrounding  a hole. 
Outside  this  ring  is  a collar  of  patterned  cuticle  which  is  more  than  three  times  the  diameter  of  the  hole.  The 
pattern  consists  of  a reticu'um  of  thickened  cuticle  defining  elliptical  and  lunate  shapes.  In  the  other  specimens 
(41 1 . 7 . 37,  41 1 . 19.96)  the  morphology  appears  to  be  identical,  as  far  as  can  be  made  out  in  these  less  well 
preserved  examples.  In  no  case  is  a hair  seen  emerging  from  the  hole. 

In  the  original  description,  the  podomere  bearing  the  well  preserved  example  (41 1 .7.86)  was  described  as 
a possible  femur  because  its  distal  end  appears  to  have  an  inferior  emargination  (Shear  et  al.  1987,  fig.  149). 
Now  that  the  femur  of  Ecchosis  pulchribothrium  is  known,  it  is  certain  that  the  earlier  described  podomere  is 
not  a femur.  Specimen  411  7.86  could,  however,  be  another  patella.  The  bothrium  occurs  adjacent  to  the 
superior  distal  articulation;  slit  sensilla  may  be  present  on  the  emarginated  inferior  side  of  the  distal  joint,  but 
could  not  be  seen  because  of  the  folding  (Shear  et  al.  1987,  fig.  149).  Both  the  inferior  side  and  the  proximal 
joint  are  not  well  preserved  in  41 1 .7.86;  it  is  uncertain  whether  this  specimen  represents  a different  podomere 
with  the  same  kind  of  trichobothrial  base,  or  another  patella. 

The  third  specimen  bearing  an  ornamented  trichobothrial  base  (411.19.96,  PI.  6,  fig.  3)  resembles  a 
trochanter  at  first  sight;  closer  inspection,  however,  reveals  that  it  has  been  proximodistally  compressed  to 
some  degree,  and  the  proximal  joint  is  incompletely  preserved.  It,  too,  could  be  a patella.  The  preserved  inferior 
surface  is  short,  and  bears  three  groups  of  slit  sensilla.  Two  of  these  are  situated  close  to  the  inferior  articulation 
(which  is  not  strongly  developed),  and  they  diverge  distally  at  an  angle  from  the  midline.  The  other  group 
diverges  at  an  80°  angle  from  the  first  two  groups,  and  is  situated  on  the  other  side  of  the  midline  from  them. 
The  trichobothrial  organ  is  obscured  by  folding;  it  is  situated,  like  those  on  the  other  two  podomeres,  a short 
distance  behind  and  a little  to  one  side  of  the  superior  distal  articulation. 

Tibia.  Only  the  fragment  attached  to  the  patella  in  41 1 .7.37,  described  above,  is  known  with  certainty.  This 
piece  has  superior  and  inferior  proximal  articulations.  It  is  interesting  in  that  its  lateral  sides  appear  to  diverge 
distally;  possibly  it  was  a tumid  podomere  in  this  leg  in  life.  In  addition,  a number  of  examples  of  a long 
podomere  with  extremely  large  setal  sockets  occurs  among  the  specimens;  411.19. 188  (PI.  7,  fig.  8)  and  329.46 
are  good  examples.  The  proximal  end  of  the  podomere  does  not  occur  on  any  of  these  specimens,  but  these 
podomeres  are  at  least  three  times  as  long  as  wide,  and  have  two  rows  of  large  sockets,  each  row  with  at  least 
8 sockets,  along  their  length.  In  addition  to  the  rows  of  major  sockets,  there  are  about  10  rows  of  smaller  setal 
sockets  running  along  the  length  of  the  podomere.  There  is  commonly  a smaller  seta  adjacent  to  each  major 
socket.  The  large  sockets  bear  thick,  spindle-shaped  movable  spines,  each  about  four  times  as  long  as 
maximally  wide  in  the  compressed  state.  The  spines  have  straight  striations  running  along  their  length,  are 


EXPLANATION  OF  PLATE  7 

Figs  1.  3,  4.  7.  8.  Ecchosis  pulchribothrium  gen.  et  sp.  nov.  1,  inferodistal  part  of  femur,  inferior  to  top,  distal 
to  right,  showing  cuticle  sculpture,  411.1.33,  x 53.  3,  part  of  distal  joint  of  unknown  podomere  showing  slit 
sensilla  grouped  into  lyriform  organ,  411.19.184,  x 72.  4,  thick,  striated,  bifid  spine  on  unknown  podomere, 
411.19.137,  x 53.  7,  patch  of  cuticle  (part  of  body  not  known)  showing  cuticle  sculpture,  41 1 . 19.206,  x 89. 
8,  superodistal  part  of  unknown  podomere  showing  cuticle  sculpture,  setae,  spine  and  their  sockets,  and 
lyriform  organ,  411.19.188,  x 1 18. 

Figs  2 and  6.  Extant  amblypygid  Heterophrynus  elaphus , specimens  cleared  in  potassium  hydroxide.  2, 
trichobothrial  base  adjacent  to  superior  articulation  at  distal  joint  of  tibia  4,  x 135.  6,  left  chelicera,  ectal 
aspect,  dense  setation  around  teeth  removed  for  clarity,  transmitted  light  under  ethanol  on  Olympus  SZH 
stereomicroscope,  x 7-5. 

Fig.  5.  Extant  uropygid  Mastigoproctus  giganteus,  left  chelicera,  mesal  aspect,  specimen  cleared  in  potassium 
hydroxide,  dense  setation  around  teeth  removed  for  clarity,  transmitted  light  under  ethanol  on  Olympus 
SZH  stereomicroscope,  x 7-5. 


PLATE  7 


SELDEN  et  a/.,  Ecchosis , Mastigoproctus , Heterophrynus 


278 


PALAEONTOLOGY.  VOLUME  34 


broad  at  the  base,  and  have  a bifid  tip  (PI.  7,  fig.  4).  The  normally  shaped  macrosetae  present  on  the  podomeres 
are  also  striated,  and  do  not  have  bifid  tips.  The  smallest  setae  are  relatively  short.  The  distal  end  of  one 
podomere  is  preserved  (PI.  7,  fig.  8),  and  shows  a longitudinal  lyriform  organ. 

There  is  no  conclusive  evidence  of  the  identity  of  these  large  podomeres.  The  short  trochanter  and  patella, 
and  the  terminal  tarsus  can  all  be  ruled  out.  Of  the  long  podomeres,  all  pulmonate  metatarsi  have  a lyriform 
or  group  of  slit  sensilla  at  the  distal  end,  in  which  the  slits  are  aligned  transversely.  Pulmonate  femora  bear 
rows  of  slit  sensilla  rather  than  lyriforms,  characteristic  articulation  points,  and  are  normally  distinctly 
emarginated.  It  is  therefore  most  likely  that  the  long  podomeres  represent  tibiae.  Well  developed  lyriform 
organs  occur  on  the  distal  ends  of  the  tibiae  of  spiders,  but  not  of  amblypygids  or  uropygids  (Barth  1978, 
fig.  3). 

Discussion.  Is  the  ornamented  sense  organ,  which  is  one  of  the  characteristics  of  Ecchosis , a true 
trichobothrium?  Among  living  arachnids,  the  trichobothrium  is  fairly  widespread,  occurring  in  all 
groups  except  Ricinulei,  Solifugae,  and  Opiliones.  Ornamented  trichobothrial  bases  are  known 
from  living  spiders,  although  none  has  the  same  type  of  pattern  see  in  Ecchosis.  It  is  also  rare  to  find 
a trichobothrium  on  the  patella  of  an  arachnid;  they  occur  more  commonly  on  the  more  distal 
podomeres  of  the  legs.  A literature  search  for  spiders  with  patellar  trichobothria  revealed  none,  and 
R.  Forster  (pers.  comm.)  is  aware  of  no  spider  with  patellar  trichobothria.  However,  a study  of 
specimens  of  other  Pulmonata  revealed  that  whereas  uropygid  patellae  bear  no  trichobothria,  they 
are  present  on  the  patellae  of  legs  2,  3,  and  4 of  Amblypygi.  Weygoldt  (1972)  described  two 
trichobothria  on  each  walking-leg  (2,  3,  4)  patella  of  all  species  of  Charinus , and  we  observed  this 
same  pattern  on  Heterophrynus  elaphus.  Quintero  (1980)  described  these  organs  on  the  patella  of 
Acanthophrynus  coronatus , and  called  them  ‘campaniform  sensilla’,  but  they  do  not  seem  to  differ 
in  morphology  from  the  tibial  trichobothria.  They  bear  a fine  hair  emerging  from  the  central  hole, 
as  drawn  by  Quintero  (1980,  fig.  6)  and  so  are  not  campaniform  sensilla.  Of  especial  interest  is  the 
ornamentation  of  the  collar  (PI.  7,  fig.  2);  it  is  remarkably  similar  to  that  observed  in  E. 
pulchribothrium , and  quite  different  from  that  on  the  trichobothria  found  on  uropygids  and  spiders. 
The  patella  of  amblypygids  is  different  in  shape  from  that  of  E.  pulchribothrium , being  specialized 
for  immobility  and  twisted  to  enable  the  crevice  locomotion  of  these  bizarre  animals  (Manton  1977), 
so  that  whilst  their  patellar  trichobothria  lie  adjacent  to  the  superior  distal  articulation,  this 
articulation  is  situated  in  a triangular  notch  in  the  distal  edge  of  the  podomere. 

It  is  therefore  possible  that  Ecchosis  is  an  amblypygid,  but  without  additional  evidence,  the  genus 
cannot  be  assigned  to  that  group.  It  is  probable  that  in  the  Devonian  there  were  Pulmonata  with 
a mosaic  of  characters  which  today  are  found  iu  separate  taxa. 


Class  arachnida  Lamarck,  1801  incertae  sedis 
Plate  5,  figs  3 and  4 

Five  specimens  (329 . 60,  329 . 62,  334.  In.  4,  41 1 .2.4,  2002 .9.20:  PI.  5,  figs  3 and  4)  of  lengths  of  short  segments 
are  present  in  the  Gilboa  material.  The  segments  are  about  one  and  a half  times  as  long  as  wide  and  all  are 
virtually  identical,  apart  from  the  terminal  one  in  some  specimens.  No  more  than  12  occur  together.  Each  has 
a distal  collar  into  which  the  next  succeeding  segment  is  inserted,  and  this  collar  bears  setal  sockets  all  round. 
The  cuticle  is  patterned  with  transversely  elongate  reticulate  sculpture,  and  scattered  across  the  surface  are 
some  small  pores  which  resemble  the  little  slit  sensilla  of  Attercopus  (they  differ  slightly,  however,  in  that  these 
always  appear  eliptical  or  lunate  even  at  low  magnification).  The  setae  are  very  long  and  thin,  and  do  not  have 
bifid  tips  (there  arc  many  specimens  of  another  type  of  flagellar  appendage  in  which  the  segments  are  about 
three  times  as  wide  as  long,  in  the  compressed  state,  in  which  the  setae  have  bifid  tips  with  branches  of  different 
lengths).  There  is  no  evidence  to  link  these  flagellar  appendages  with  any  arachnids,  except  that  the  little  pores, 
if  they  are  slit  sensilla,  would  confirm  an  arachnid  rather  than  any  other  arthropod  group.  These  organs  might 
be  the  caudal  flagellum  of  a uropygid  (and  evidence  is  amounting  that  Gelasinotarbus  bonamoae  may  prove  to 
be  one  of  these  animals)  or  could  be  the  flagelliform  first  leg  of  an  amblypygid.  Similar  antenniform  appendages 
with  slit  sensilla  have  also  been  found  in  Stephanian  deposits  from  Kansas  (A.  J.  Jeram,  pers.  comm.). 


SELDEN  ET  A L. : DEVONIAN  ARACHNIDS 


279 


Acknowledgements.  We  thank  Ray  Forster  and  Norman  Platnick  for  sharing  their  observations  on  the 
morphology  of  a wide  range  of  pulmonate  arachnids  with  us,  Andy  Jeram  for  information  on  the  many  new 
fossil  Pulmonata  he  is  turning  up,  and  Jonathan  Coddington  and  Jacqueline  Palmer  for  discussion  on  the 
identity  of  the  spinneret.  We  thank  Sam  Morris  and  Norman  Platnick  for  the  loan  of  material  in  the  care  of 
The  British  Museum  (Natural  History)  and  The  American  Museum  of  Natural  History  respectively,  and 
W.  Struve  (Senckenberg  Museum)  for  the  preparation  and  loan  of  a plaster  cast  of  Archaeometa?  devonica. 
P.A.S.  is  extremely  grateful  to  the  faculty  and  staff  of  Hampden-Sydney  College  for  their  hospitality  during 
an  extended  study  visit  in  1989.  This  work  was  supported  by  a grant  from  the  US  National  Science  Foundation 
(BSR  88-180-27)  to  W.A.S.  and  P.M.B.,  and  by  travel  funds  for  P.A.S.  from  The  University  of  Manchester 
and  The  Royal  Society  of  London. 


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281 


PAUL  A.  SELDEN 

Department  of  Extra-Mural  Studies 
University  of  Manchester 
Manchester  M13  9PL,  UK 

WILLIAM  A.  SHEAR 

Department  of  Biology 
Hampden-Sydncy  College 
Hampden-Sydney,  Virginia  23943,  USA 


Typescript  received  2 February  1990 
Revised  typescript  received  31  March  1990 


PATRICIA  M.  BONAMO 

Center  for  Evolution  and  the  Paleoenvironment 
State  University  of  New  York 
Binghamton,  New  York  13901,  USA 


ORDOVICIAN  G RAPTOLITES  FROM  THE  EARLY 
HUNNEBERG  OF  SOUTHERN  SCANDINAVIA 

by  KRISTINA  LINDHOLM 


Abstract.  A graptolite  fauna  of  Early  Hunneberg  age  is  described  from  southern  Scandinavia  (Scania, 
Vastergotland,  Oslo  region).  Correlation  and  boundaries  within  the  interval  are  discussed  and  it  is  suggested 
that  the  Hunneberg  Stage  be  elevated  to  series  rank,  interposed  between  the  Tremadoc  and  the  Arenig.  One 
new  dichograptid  genus,  Hunnegraptus , and  three  Scandinavian  representatives  of  it,  H.  copiosus , H.  tjernviki , 
and  H.  robustus , are  erected.  The  genus  is  multiramous,  with  long  first-order  stipes,  and  shows  presumed 
rejuvenation  of  gerontic  specimens.  It  is  likely  to  be  most  closely  related  to  Clonograptus.  Six  additional  species 
are  formally  named:  Kiaerograptus  supremus  (Anisograptidae),  Clonograptus  (C.)  magnus,  Tetragraptus 
longus,  T.  krapperupensis  (Dichograptidae),  Paradelograptus  elongatus,  and  P.  tenuis  (Sinograptidae).  The 
sequence  containing  these  taxa  is  divided  into  three  zones:  the  K.  supremus  Zone  which  probably  starts  in  the 
Late  Tremadoc,  the  A.  murrayi  Zone,  and  above  that  the  H.  copiosus  Zone,  which  underlies  the  Late 
Hunneberg  Tetragraptus  phyllograptoid.es  Zone.  The  fauna  covers  part  of  the  interval  when  anisograptids  gave 
way  to  graptolites  of  the  dichograptid  development  stage,  and  the  observed  steps  in  this  evolution  (loss  of 
bithecae)  are  described. 


Graptolites  from  the  Upper  Tremadoc  and  Lower  Arenig  of  southern  Scandinavia  have  been 
known  for  over  a hundred  years,  e.g.  Tullberg  (1880),  Holm  (1881),  Brogger  (1882),  Herrmann 
(1883,  1885),  Tornquist  (1901,  1904),  Strandmark  (1902),  Monsen  (1925,  1937),  Spjeldnaes  (1963), 
and  Erdtmann  (1965a).  Yet,  the  fauna  described  in  this  paper,  which  comes  from  a ‘post-Tremadoc, 
pre-Arenig'  level,  remained  unrecognized  until  Tjernvik  (1956)  made  his  overview  of  the  Lower 
Ordovician  of  Sweden.  From  a darker  band  in  a grey  shale  unit  at  Storeklev,  at  Mt  Hunneberg 
(Text-fig.  1 A),  he  mentioned  a few  peculiar  graptolites,  which  he  referred  to  as  ‘undescribed 
dichograptids’  in  his  correlation  table.  No  description  of  this  fauna  has  been  given  to  this  day.  The 
fauna,  together  with  several  accompanying  species,  was  later  found  in  lithologically  similar  beds  in 
the  Oslo  region,  mainly  by  N.  Spjeldnaes  in  the  Slemmestad  area  and  by  B.-D.  Erdtmann  in  central 
Oslo.  More  recently,  I re-collected  both  the  Storeklev  and  the  Slemmestad  localities.  Finally,  I 
identified  the  fauna,  and  also  older  post-Tremadoc  graptolites,  in  a grey  to  nearly  black  shale 
sequence  in  the  Krapperup  drillcore  in  NW  Scania.  The  rarity  of  identifiable  graptolites  in  the  basal 
beds  of  the  core  and  absence  of  the  otherwise  ubiquitous  Ceratopyge  Limestone  make 
lithostratigraphic  and  chronostratigraphic  correlation  of  these  basal  beds  difficult.  Judging  by 
circumstantial  evidence,  however,  all  of  the  basal  beds  probably  belong  to  the  Hunneberg. 

From  my  own  observations  in  the  Lower  Ordovician  of  southern  Scandinavia  (Lindholm 
1991),  a closely  similar  sequence  of  facies  and  faunas  is  developed  in  the  Oslo  region,  Mt 
Hunneberg  in  Vastergotland,  and  SE  Scania.  All  areas  can  be  regarded  as  lying  within  a single 
confacies  belt,  equivalent  to  Jaanusson’s  (1976,  1982)  Scanian  and  Oslo  confacies  belts,  at  least  until 
the  end  of  Arenig  time.  They  undoubtedly  represent  a single,  original  depositional  basin  which 
included,  as  a thicker  and  further  offshore  facies,  the  NW  Scanian  sequence  of  the  Krapperup  bore 
core. 

All  three  areas,  Oslo,  Mt  Hunneberg,  and  Krapperup,  have  been  cut  by  various  forms  of  late 
Carboniferous  to  early  Permian  intrusives.  In  other  respects,  the  geological  settings  of  the  three 
areas,  as  seen  today,  differ  due  to  their  later  geological  history.  The  Oslo  region  is  a large,  more  or 
less  continuous  area  of  well  exposed  Cambrian  to  Silurian  sediments  close  to  the  Scandinavian  fold 


| Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  283-327. | 


© The  Palaeontological  Association 


284 


PALAEONTOLOGY.  VOLUME  34 


text-fig.  1.  Location  of  the  study  area,  a.  Outline  map  showing  location  of  investigated  localities,  b.  Detail 
map  of  the  Slemmestad  area,  showing  the  structural  complexity;  redrawn  from  Bockelie  (1982).  The  main 
sampling  localities  of  Lower  Hunneberg  rocks  were  the  coastal  sections  at  Grundvik  and  Hagastrand,  a road- 
cut  just  south  of  Slemmestad  crossroads  (eastern  side  of  the  road),  the  new  standard  section  (1 ; western  side 
of  the  road),  and  a long  continuous  roadside  exposure  (western  side)  marked  ‘2’.  This  is  the  ‘ Rortunet  ’ section 
(Bodalen  or  Buss-stop  Nybygget  of  previous  collectors),  which  is  most  complete  stratigraphically  at  its 
southern  end.  It  is  cut  by  a couple  of  minor  thrust  faults  and  Permian  dykes.  South  of  area  ‘2’  is  another 
roadside  exposure  (western  side),  partly  hidden  behind  trees.  This  section  is  the  Kiaerograptus  locality  of 
Spjeldnaes  (1963)  which,  however,  also  contains  Hunneberg  age  beds.  In  addition,  a few  samples  are  labelled 
with  street  names,  and  one  sample  derives  from  the  islet  Gjeitungholmen. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GR APTOLITES 


285 


belt.  The  beds  are  gently,  to  somewhat  more  complexly,  folded,  with  minor  associated  thrust  faults 
particularly  in  the  Slemmestad  area  where  structure  can  be  easily  observed  (Text-tig.  I B).  Mt 
Hunneberg,  on  the  other  hand,  constitutes  a very  small,  isolated  but  well  exposed  area  of  Cambrian 
and  Lower  Ordovician  sediments  on  a Precambrian  basement,  protected  by  a thick  dolerite  cap.  The 
beds  are  flat-lying.  Finally,  the  Krapperup  area  (NW  Scania)  is  a small  (1x7  km)  fault-bounded 
block,  surrounded  by  Mesozoic  rocks,  and  lying  within  a zone  of  intense  block  faulting,  the 
individual  blocks  of  which  are  sometimes  less  than  1 km  in  width.  The  NW  Scania  area  forms  part 
of  a broad  tract  of  discontinuous  outcrops,  extending  from  NW  to  SE  Scania,  of  Lower  Palaeozoic 
rocks.  The  beds,  and  graptolite  faunas  described  here,  however,  are  known  only  from  the  western 
part  of  Scania. 

STRATIGRAPHY 

Zonation  of  the  sequence.  In  Scandinavia,  the  interval  from  the  base  of  the  Ceratopyge  Limestone 
to  the  base  of  the  T.  phyllograptoid.es  Zone  (roughly  corresponding  to  the  faunas  described  herein) 
has  not  formally  been  divided  into  graptolite  zones;  a ‘ Didymograptus ? stoenneri  Zone’  was 
indicated  by  Erdtmann  (1965b,  text-fig.  5;  not  defined  in  text)  for  the  time  interval  spanning  the 
Ceratopyge  Limestone,  but  based  on  finds  from  the  very  top  of  the  unit  only  (Erdtmann  1965a, 
p.  108).  The  same  graptolite  fauna  is  also  present  in  W.  Scania,  in  the  Fagelsang  core  (Hede  1951 ; 
"D.  balticus'  Zone,  followed  by  a major  hiatus).  Here,  D.  ? stoenneri  is  found  well  above  the 
Ceratopyge  Limestone.  The  species  was  not  found  in  the  Krapperup  core,  despite  examination  of 
every  cm  of  the  lowermost  metres  of  the  core,  nor  was  anything  else  as  primitive-looking. 

I propose  a subdivision,  based  on  the  Krapperup  core  sequence,  into  (Text-fig.  2):  a Kiaerograptus 
supremus  Zone  (Krapperup  core,  155-06  m (base)-148-22  m);  an  Araneograptus  murrayi  Zone 
(148-22  m-132-73  m);  and  a Hunnegraptus  copiosus  Zone  (132-73  m-1 12-80  m).  The  base  of  the  K. 
supremus  Zone  corresponds  to  an  undefined  level  within  the  Ceratopyge  Limestone.  The  bases  of 
the  A.  murrayi  and  H.  copiosus  Zones  are  defined  by  the  incoming  of  their  zone  fossils.  The  base 


NW  SCANIA  HUNNEBERG  OSLO 


WALES 


D.  balticus 

T.  phyilo- 
graptoides 


H.  copiosus 


D.  balticus 


T.  phyllo- 
graptoides 


H.  copiosus 


D.  balticus 

T.  phyllo- 
graptoides 


H.  copiosus 


Aremig 


Hiatus 


A.  murrayi 
K.  supremus 


M.  (E.)\ 


armata 


X"'  ' i i i * i 1 i i 

A,  SBrratus  £ 


Hiatus? 


^4.'  serratus  l 

~T  T T AT  T T Y T ~t 


? 

A.  sedgwicki 


? 


Hiatus 


S.  pusilla 


S.  pusilia 


text-fig.  2.  Attempted  correlation  of  part  of  the  Lower  Ordovician  between  Scandinavia  and  Wales.  The 
lithologies  are  clastic,  except  where  indicated;  * shows  stratigraphic  position  of  beds  described  by  Molyneux 

and  Doming  ( 1989). 


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PALAEONTOLOGY,  VOLUME  34 


of  the  overlying  T.  phyllograptoides  Zone  is  defined  by  the  incoming  of  T.  phyllograptoides  or  a 
considerable  increase  in  horizontal  and  reclined  tetragraptids,  whichever  comes  first,  and  roughly 
corresponds  to  the  base  of  the  T.  approximatus  Zone  elsewhere.  The  approximate  distribution  of 
species  is  shown  in  Text-figure  3. 


text-fig.  3.  Summary  of  observed  ranges  of  taxa  present  in  topmost  Tremadoc  to  Lower  Hunneberg  beds  in 
southern  Scandinavia.  (1)  indicates  estimated  relative  position  of  the  graptolite-rich  horizon  at  Mt  Hunneberg 

and  in  the  Oslo  region. 


The  case  for  a Hunneberg  Series.  It  has  long  been  known  (e.g.  Skevington  1966)  that  there  is  a 
sizeable  hiatus  between  the  Tremadoc  and  the  Arenig  in  their  respective  type  areas  in  Wales.  The 
fauna  described  herein,  of  Hunneberg  age,  fits  into  this  hiatus.  Also,  there  is  no  general  agreement 
yet  as  to  where  to  put  the  boundary  between  the  Tremadoc  and  the  Arenig.  This  uncertainty 
concerns  mainly  beds  of  an  age  corresponding  to  La  2-La  3 in  the  Australasian  stratigraphic 
scheme,  and  sometimes  also  beds  of  Be  1 -Be  2 age  (e.g.  Rushton  1985).  As  things  stand,  the 
Hunneberg  interval  can  thus  be  regarded  in  four  different  ways: 

1.  as  a series  filling  the  gap  between  the  Tremadoc  and  the  Arenig; 

2.  as  the  basal  stage  of  the  Arenig; 

3.  as  the  topmost  stage  of  the  Tremadoc; 

4.  as  part  Tremadoc,  part  Arenig. 

The  trend  is  nowadays  towards  a reduction  of  the  number  of  series,  e.g.  the  suggested 
amalgamation  of  the  Llanvirn  and  the  Llandeilo.  Still,  I am  in  favour  of  the  introduction  of  a new 
Hunneberg  Series,  interposed  between  the  Tremadoc  and  the  Arenig,  as  previously  suggested  by 
Erdtmann  (1988).  In  my  opinion,  this  is  the  easiest  way  round  a difficult  problem.  Even  from  the 
British  point  of  view,  it  would  be  an  advantage:  what  is  now  Tremadoc  and  Arenig  in  their 
respective  type  areas  would  remain  so,  whereas  the  beds  of  ‘ uncertain ' age  in  the  Lake  District  and 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GR APTOLITES 


287 


South  Wales  described  by  Rushton  (1985),  Molyneux  and  Rushton  (1988),  and  Molyneux  and 
Doming  (1989)  would  belong  to  the  Hunneberg.  The  beds  described  in  the  above  papers  are  all  of 
La  2 age.  My  examination  of  the  graptolites  described  by  Molyneux  and  Rushton  (1988)  and 
comparison  with  Scandinavian  and  Spanish  material  proves  them  to  be  considerably  older  than  the 
T.  approximatus  Zone  (La  3). 

I would  recommend  a Hunneberg  Series  of  the  extent  originally  suggested  by  Tjernvik  ( 1956),  not 
the  revised  concept  of  Tjernvik  and  Johansson  (1980)  who  referred  the  topmost  zone,  that  of  D. 
balticus / M . (V.)  aff.  estonica  ('Transition  beds’),  to  the  overlying  Billingen  Stage.  It  seems  that  the 
most  practical  definition  of  the  Hunneberg  Series  would  be  in  terms  of  conodonts,  as  comprising 
the  conodont  zones  of  P.  proteus  and  P.  elegans.  This  would  closely  fill  the  Tremadoc/Arenig  hiatus 
in  the  type  areas.  The  base  of  the  Hunneberg  would  correspond  to  the  Scandinavian  top  of  the 
Tremadoc,  however,  which  is  equivalent  to  a level  higher  than  the  top  of  the  Tremadoc  in  its  type 
area  in  Wales  (Skevington  1966;  Henningsmoen  1973).  From  elsewhere  in  Wales  and  adjacent 
areas,  Rushton  (in  Whittington  et  al.  1984)  mentions  younger  beds  which  he  refers  to  the  Tremadoc. 
He  includes  a trilobite  fauna  correlated  with  the  Shumardia  pusilla  Zone  of  Scandinavia  which 
(Regnell  1960)  lies  within  the  Ceratopyge  Shale,  and  a younger  Angelina  sedgwicki  Zone  fauna 
which  cannot  be  correlated  with  Scandinavia.  Therefore,  beds  equivalent  to  the  Scandinavian 
topmost  Tremadoc  Apatokephalus  serratus  Zone  (Ceratopyge  Limestone)  are  not  definitely  known 
in  Wales.  An  approximate  correlation  between  the  Scandinavian  and  Welsh  faunas  is  given  in  Text- 
figure  2. 

The  top  of  the  graptolite  sequence  here  described  is  considerably  older  than  the  oldest  graptolite 
fauna  in  the  type  area  of  the  Arenig.  That  fauna  was  described  by  Zalasiewicz  (1986)  and 
corresponds  to  a level  no  lower  than  the  upper  part  of  the  D.  balticus  Zone  or  more  probably  the 
P.  densus  Zone  of  Scandinavia  (Lindholm  1991).  According  to  Fortey  and  Owens  (1987,  p.  99) 
no  strata  of  Tetragraptus  approximatus  Zone  age  have  been  proven  to  exist  in  Wales,  although  they 
suspect  rocks  equivalent  in  age  to  the  upper  part  of  the  zone  to  be  present.  All  of  the  graptolite  fauna 
described  herein  appears  to  be  older  than  the  T.  approximatus  Zone. 

Cooper  and  Lindholm  (1991)  have  made  an  attempt  at  estimating  the  relative  duration  of  the 
different  intervals  in  the  Early  Ordovician.  That  study  indicates  that  the  duration  of  the  Hunneberg 
Series,  as  proposed  here,  is  longer  than  the  Tremadoc,  taken  as  the  Rhabdinopora  flabelliformis 
desmograptoides  Zone  - Apatokephalus  serratus  Zone  (the  Scandinavian  concept).  It  is  only  slightly 
shorter  than  the  ‘remaining’  Arenig  and  of  approximately  equal  length  to  the  combined 
Llanvirn-Llandeilo.  A further  argument  for  a Hunneberg  Series  is  the  disagreement  between 
workers  on  different  fossil  groups  if  the  beds  in  question  are  ‘Tremadoc’  or  ‘Arenig’  in  age. 
Graptolite  workers  have  generally  considered  the  ‘La  2’  beds  as  ‘Tremadoc’,  whereas  conodont 
workers,  working  in  different  facies,  call  coeval  beds  ‘Arenig’.  It  should  be  noted  here  that  the  base 
of  the  conodont  zone  of  P.  proteus  lies  considerably  lower  than  the  base  of  the  T.  approximatus 
Zone,  contrary  to  the  views  of  Barnes  et  al.  (1988)  (Lofgren  in  prep.).  Different  graptolitic  facies 
have  been  treated  equally  ambiguously  (Lindholm  1984):  typical  La  2 beds  have  been  referred  to 
the  Tremadoc,  whereas  the  coeval  A.  murrayi  beds  have  been  considered  to  be  of  Arenig  age  (e.g. 
Thoral  1935;  Destombes  et  al.  1969).  The  works  of  Williams  and  Stevens  (1991),  Stouge  and 
Bagnoli  (1988)  and  Lofgren  (in  prep.)  have  added  to  the  precision  in  correlation  between  the 
graptolite  and  conodont  zonation.  According  to  conodont  evidence,  the  lower  part  of  the  La  2 
graptolite  fauna  is  of  Tremadoc  age  (that  described  by  Williams  and  Stevens  (1991)  from 
Newfoundland)  whereas  higher  parts  (this  work)  belong  to  the  P.  proteus  conodont  zone,  generally 
regarded  as  of  Arenig  age. 


LOCALITIES 

In  Scandinavia,  the  Lower  Hunneberg  beds  outcrop  only  in  the  Oslo  region  (east-central  Oslo  and  Slemmestad) 
and  at  Mt  Hunneberg.  In  Scania  they  are  known  only  from  the  Krapperup  core,  the  basal  beds  also  from  the 
Fagelsang  core  (D.  balticus  Zone  of  Hede  (1951)).  Based  on  lithological  similarity,  they  appear  to  be  present 


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PALAEONTOLOGY,  VOLUME  34 


both  further  to  the  south  (SE  Scania)  and  to  the  north  (Hanrar  at  Lake  Mjosa).  These  beds  are,  however, 
unfossiliferous. 

The  only  graptolite-bearing  outcrop  of  Lower  Hunneberg  beds  at  Mt  Hunneberg  is  at  Storeklev,  in  the 
south-west  wall  of  the  mountain.  Here,  the  Lower  Hunneberg  is  represented  by  shale,  and  is  thicker  than 
elsewhere.  The  sequence  gradually  thins  and  shale  gives  way  to  limestone  towards  the  eastern  wall  of  the 
mountain.  At  Storeklev,  graptolites  are  found  scattered  through  the  lower  part  of  the  shale,  within  which  there 
is  one  rich  band,  2- 15-2-32  m above  the  hiatus  separating  the  Cambrian  from  Ordovician  beds  (Tjernvik  1956). 
The  collections  investigated  from  Storeklev  consist  of  T.  Tjernvik’s  original  material  (PU  Vg  124-127), 
B.-D.  Erdtmann’s  collections  from  the  early  1960s  (TUB  HUN-S/2.  18-2.3/001-058)  and  my  own  collections 
from  1979-1986,  belonging  to  Lund  University. 

The  Oslo  region,  c.  200  km  north-west  of  Mt  Hunneberg,  contains  several  outcrops  of  Lower  Ordovician 
graptolite  shale,  but  the  Lower  Hunneberg  beds  are  found  only  in  the  central  part,  at  Galgeberg  and  Toyen 
(both  in  east-central  Oslo)  and  in  the  Slemmestad  area  (c.  20  km  south-west  of  the  Oslo  localities).  The 
Galgeberg  and  Toyen  localities  were  temporary  construction  sites,  and  are  now  inaccessible,  whereas  the 
Slemmestad  area  contains  several  well-exposed  localities  (road  sections  and  beach  sections;  Text-fig.  I b).  My 
own  collecting  at  Slemmestad  has  shown  the  graptolites  to  be  less  rare  than  at  Storeklev,  but  at  both  localities 
there  are  unusually  rich  horizons.  The  collections  investigated  from  the  Oslo  region  consist  of  material  from 
Galgeberg  collected  in  the  1930s  by  T.  Strand  and  A.  Heintz  (PMO  58.965-58.970);  B.-D.  Erdtmann’s 
collection  from  the  Toyen  underground  station  (GPIT1-T30;  PMO  73.652);  collections  from  various 
localities  in  the  Slemmestad  area,  mainly  by  N.  Spieldnaes,  to  a minor  extent  by  G.  Henningsmoen  and 
D.  Bruton  (PMO  137,  73.187-73.192,  73.200,  73.204,  97.702,  97.705-97.706,  97.708,  108.557-108.574, 
108.598-108.599,  112.966-1  12.970,  113.031-113.033,  120.751);  and  finally,  my  own  collections  from 
various  localities  in  the  Slemmestad  area  - the  most  productive  one  being  Grundvik  between  Slemmestad  and 
Naersnes  to  the  south.  My  collections  are  all  measured  in  sections,  and  belong  to  Lund  University. 

The  investigated  part  of  the  Krapperup  core  (situated  c.  230  km  S of  Mt  Hunneberg)  consists  of  the 
lowermost  c.  42  m (155  06-112-80  m),  comprising  the  Lower  Hunneberg  beds.  193  samples,  not  all  of  which 
contained  identifiable  graptolites,  have  been  taken  out  of  this  part  of  the  core.  The  core  was  drilled  in  the 
1940s  and  belongs  to  Lund  University.  Its  diameter  is  62  mm. 

All  the  material  examined  consists  of  medium  grey  to  almost  black,  non-calcareous,  shale/mudstone.  The 
preservation  of  the  graptolites  varies  from  flattened  to  full  relief,  infilled  with  pyrite  or,  commonly  in  the 
lowermost  part  of  the  Krapperup  core,  with  calcite.  In  the  latter  case,  the  periderm  is  usually  very  brittle  and 
partly  flakes  off  during  splitting  of  the  slab  or  preparation.  Also,  some  of  these  graptolites  were  partly 
compressed  and  deformed  before  infilling  with  calcite.  They  are,  consequently,  often  hard  to  identify. 

GRAPTOLITE  TERMINOLOGY 

The  terminology  in  general  follows  that  of  Bulman  (1970)  and  Cooper  and  Lortey  (1982,  1983;  isograptid 
development  type,  dextral  and  sinistral  mode,  consecutive  and  delayed  dichotomies  etc.).  Didymograptid  and 
tetragraptid  proximal  part  refers  to  the  length  of  first-order  stipes  (several  vs.  one  theca  each).  Profile  stipe 
width  refers  to  measurements  made  from  the  dorsal  edge  of  the  specimen  to  the  ventral  wall  of  a theca,  at  its 
aperture  - the  aspect  of  the  stipe  is  referred  to  as  "profile  view'.  Lateral  stipe  width  refers  to  specimens  in  dorsal 
or  ventral  view  ("dorsoventral  view' ; horizontal  preservation  of  multiramous  specimens),  that  is,  measurements 
are  made  from  side  to  side  of  the  stipe.  The  number  of  thecae  in  10  mm  has  usually  been  measured  over  the 
available  number  of  thecae,  and  then  recalculated.  Stipe  divergence  angles  are  measured  as  the  angle  resulting 
from  the  tangents  of  the  dorsal  side  of  the  stipes  across  a specified  thecal  aperture.  Secondary  cortex  cover  in 
general  refers  to  what  appears  to  be  an  'envelope'  around  the  stipe,  compressed  to  a film  in  the  bedding  plane 
in  an  arbitrary  preservational  aspect  of  the  specimen;  only  exceptionally  does  the  cortex  cover  appear  to  have 
thickened  the  stipe  into  a robust  "rod’.  The  terms  sicular  bitheca  and  plaited  thecal  structure  are  explained  in 
the  section  on  evolution.  Dichograptid  stipe  indicates  a stipe  without  triad  budding  or  plaited  thecal  structure, 
i.e.  "fully  graptoloid’.  Graptoloid  thecal  notation  is  used  throughout. 

In  the  systematic  section,  the  suprageneric  classification  of  Lortey  and  Cooper  ( 1986)  has,  in  general,  been 
followed  (see  discussion  on  the  Sigmagraptinae,  however).  In  the  synonymy  lists  the  signs  recommended  by 
Matthews  (1973)  have  been  used.  Under  the  heading  of  "Associated  species’  are  listed  only  the  species  found 
on  the  same  bedding  plane  as  the  species  under  discussion. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


289 


EVOLUTION  AND  PHYLOGENY 

The  fauna  discussed  in  this  paper  represents  a stage  in  graptolite  evolution  when  (along  various 
lineages)  biradiality  had  generally  been  attained  and  bithecae  were  in  the  process  of  being  lost.  The 
coexistence  of  sinistral  and  dextral  forms  of  a species  is  a common  feature  in  early  Elunneberg  time. 
The  fauna  does  not  verify  any  general  trend  towards  reduction  in  the  number  of  stipes  present  in 
a rhabdosome. 

Loss  of  bithecae.  Bithecae  were  lost  along  different  lineages  in  a rather  restricted  time  period.  Late 
Tremadoc  and  Early  Hunneberg.  Late  Tremadoc  graptolites  showing  various  degrees  of  bithecal 
reduction  were  described  by  Williams  and  Stevens  (1991). 

I have  not  been  able  to  verify  if  the  various  steps  in  this  transformation  follow  in  the  same  order 
(homotaxially)  in  different  groups,  nor  if  bithecae  were  lost  progressively  along  a stipe  or 
instantaneously.  I have  seen  a limited  number  of  combinations  of  primitive  and  advanced  traits 
(Text-fig.  4a)  that  can  be  listed  as  five  steps  in  a morphological  series: 

1.  The  typical  anisograptid : a fully  bithecate  rhabdosome,  with  normal  triad  budding,  i.e. 
successive  groups  of  one  autotheca,  one  bitheca,  and  a stolotheca,  produced  at  stolonal  nodes. 
These  groups  alternate  regularly  (Bulman  1970,  fig.  8),  so  that,  from  one  side  of  the  rhabdosome, 
only  every  second  bitheca  can  be  seen  (Text-fig.  4a:  1,  B).  In  profile  view,  the  thecae  are  seen  to  bud 
laterally  (Text-figs  4c,  d,  5a,  b).  The  alternation  is  seen  as  a zig-zag  or  sinuous  pattern  in  dorsal 
view. 

2.  A fully  bithecate  rhabdosome  with  irregularities  in  the  triad  budding,  that  is,  two  or  more 
successive  bithecae  may  be  present  on  one  side  of  the  rhabdosome  (Text-fig.  4a: 2,  c,  d),  e.g. 
Kiaerograptus  supremus. 

3.  Only  a sicular  bitheca  is  present,  i.e.  the  bitheca  associated  with  th  l1  and  present  between  the 
sicula  and  th  l1  on  the  obverse  side.  The  stipes  have  traces  of  triad  budding,  here  termed  plaited 
thecal  structure.  The  name  has  been  chosen  to  illustrate  the  zig-zag  or  sinuous  path  of  the  common 
canal,  as  seen  in  dorsal  view,  caused  by  the  fact  that  the  thecae  still  alternate,  even  though  the 
hi  thecae  have  been  lost  (Text-fig.  4a:  3,  e),  and  their  proximal  parts  produce  a 'herringbone'  or 
plaited  structure  (in  dorsal  view).  The  budding  is  closer  to  the  dorsal  side  of  the  rhabdosome  than 
in  the  bithecate  species  examined,  suggesting  the  possibility  that  the  transition  from  lateral  to  dorsal 
budding  was  a gradual  one. 

4.  The  sicular  bitheca  remains,  but  the  stipes  are  of  normal  dichograptid  appearance  (Text-fig. 
4a:  4),  as  in  Hunnegraptus  copiosus.  This  change  in  the  stipes  is  apparently  coupled  with  a reduction 
in  total  thecal  length.  A growth  stage  preserved  in  relief  (Text-fig.  4 F).  might  give  a clue  as  to  the 
disappearance  of  the  sicular  bitheca.  It  appears  to  have  the  proximal  part  of  the  bitheca,  which  has 
stopped  growing.  The  'aperture'  is  covered  by  periderm.  Since  only  one  specimen  has  been  found, 
this  interpretation  is  uncertain.  The  specimen  could  be  pathological  or  deformed  by  compression. 

5.  The  last  primitive  character,  the  sicular  bitheca,  is  lost,  and  the  'dichograptid'  development 
stage  is  reached  (Text-fig.  4a:  5). 

In  addition  to  what  I have  observed,  Williams  and  Stevens  (1991),  using  isolated  specimens, 
found  that  residual  bithecae  may  be  found  associated  with  dichotomies  after  disappearance  of 
bithecae  from  the  rest  of  the  stipes. 

Phytogeny.  The  phylogeny  of  the  fauna  is  difficult  to  trace,  mainly  because  of  the  rarity  of  well- 
preserved  graptolites  of  Late  Tremadoc  age.  What  is  evident  is  that  the  Paradelograptus  group 
nourished  in  Early  Hunneberg  time,  with  at  least  six  species  present  in  Scandinavia.  The  genus 
belongs  in  the  family  Sinograptidae  (see  further  discussion  with  systematic  descriptions)  which, 
judging  from  proximal  and  thecal  characters,  derives  its  origin  from  Adelograptus  tenellus , and 
thus  not  via  an  unspecified  dichograptid,  as  suggested  by  Lortey  and  Cooper  (1986,  text-fig.  1 1 ).  The 
Sinograptidae  constitutes  one  of  the  independent  lineages  with  bithecal  reduction.  Another  is  the 
Clonograptus  s.s.  lineage.  The  earliest  representatives  of  the  lineage  known  from  relief  material 


n+1  n+2  n+3 


290 


PALAEONTOLOGY,  VOLUME  34 


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LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


291 


(Lindholm  and  Maletz  1989)  have  a sicular  bitheca  and  plaited  thecal  structure  (C.  aft.  multiplex) 
or  a sicular  bitheca  and  normal  dichograptid  stipes  (C.  rigidus).  Lindholm  and  Maletz  (1989) 
restricted  Clonograptus  s.s.  to  species  without  bithecae  along  the  stipes.  Hunnegraptus  is  a probable 
descendant  of  an  early  Clonograptus  species  or  of  one  of  its  ancestors.  A certain  variation  in  first- 
order  stipe  length  is  known  in  Clonograptus , and  the  length  was  accentuated  in  Hunnegraptus.  It  is 
possible  that  one  group  of  didymograptids  (D.  undulatus , D.  protobalticus-balticus,  D.  geometricus 
etc.)  derives  its  origin  from  Hunnegraptus , through  suppression  of  higher-order  dichotomies. 
Likewise,  a number  of  horizontal  and  reclined  tetragraptids  (and  Dichograptus  species?)  may  derive 
their  origin  from  a species  of  Clonograptus  s.s.  related  to  C.  magnificus-multiplex . Broad  stipe 
fragments  with  thecae  of  reclined  tetragraptid  type  (long,  somewhat  curved  thecae,  with  high 
inclination  and  high  thecal  overlap)  are  sometimes  met  with  in  the  Lower  Hunneberg  fauna. 

Other  taxa  are  more  problematic.  For  instance,  did  Kiaerograptus  give  rise  to  another  group  of 
didymograptids  (another  separate  lineage  with  bithecal  reduction)  and/or  the  earliest  isograptids 
(see  p.  320)?  What  is  the  origin  of  the  early  ‘corymbograptids  ’ found  in  Scandinavia,  Britain  and 
Spain  - probably  the  very  earliest  didymograptids  - and  the  3-  and  5-stiped  forms? 


SYSTEMATIC  PALAEONTOLOGY 

Repositories  of  specimens.  Abbreviations  used  are  as  follows:  GPI,  Institute  of  Geology  and  Palaeontology, 
Gottingen,  Germany;  GSC,  Geological  Survey  of  Canada,  Ottawa,  Canada;  LO  and  LR.  Department  of 
Historical  Geology  and  Palaeontology,  Lund,  Sweden;  PMO,  Palaeontological  Museum,  Oslo,  Norway;  PU, 
Palaeontological  Institute,  Uppsala,  Sweden;  RM,  National  Museum  of  Natural  History,  Stockholm,  Sweden; 
SGU,  Geological  Survey  of  Sweden,  Uppsala,  Sweden;  TUB,  Technical  University,  Berlin,  Germany. 

Order  graptoloidea  Lapworth,  1875 

Diagnosis  (from  Fortey  and  Cooper  1986).  Graptolites  in  w'hich  the  nema  is  retained  in  the  adult 
stage. 

Incerti  subordinis 

Family  anisograptidae  Bulman,  1950 

Diagnosis  (from  Fortey  and  Cooper  1986).  Paraphyletic  group,  sicula  retains  nema  in  adult  stage, 
bithecae  present,  rhabdosome  more  or  less  bilaterally  symmetrical,  and  quadriradiate,  triradiate  or 
biradiate. 

Remarks.  The  Anisograptidae  is  a very  heterogenous  group,  with  many  of  its  biradiate  taxa  closely 
similar  to  various  taxa  within  the  Dichograptina,  the  only  difference  being  the  presence  of  bithecae 
along  the  stipes  in  anisograptids.  In  my  opinion,  to  obtain  a phylogenetically  based  classification, 
the  inclusion  of  taxa  with  bithecae  along  the  stipes  will  eventually  have  to  be  accepted  in  the 
Dichograptina,  thus  necessitating  a redefinition  of  that  group.  What  would  be  left  in  the 
Anisograptidae,  in  that  case,  would  be  its  tri-  and  quadriradiate  taxa,  which  are  probably  rather 
closely  genetically  related,  since  they  appear  in  a relatively  short  interval  of  time  just  after  the  origin 
of  planktonic  forms.  Additionally  included  would  be  those  biradiate  taxa  that  cannot  be  linked  with 
a dichograptinid  form.  For  practical  purposes,  this  change  would  make  classification  (above  the 
genus  level)  easier,  since  most  forms  are  not  well  enough  preserved  to  reveal  bithecae. 


Genus  kiaerograptus  Spjeldnaes,  1963 
Type  species.  Kiaerograptus  kiaeri  (Monsen,  1925). 

Diagnosis  (based  on  Spjeldnaes  1963;  Rushton  1981;  and  author’s  observations).  Rhabdosome 
biradiate,  composed  of  two  reclined  to  declined  stipes,  one  of  which  may  be  aborted  after  the  first 


292 


PALAEONTOLOGY,  VOLUME  34 


theca;  one  stipe  may  branch  near,  or  at  some  distance  from,  the  sicula.  In  some  rare  cases,  an  extra 
proximal  theca  may  represent  an  aborted  third  stipe.  Autothecae  are  of  dichograptid  type  but  may 
have  isolated  distal  parts.  Bithecae  present  at  sicula  and  along  stipes.  Triad  budding  not  always 
regular. 


Kiaerograptus  supremus  sp.  nov. 

Text-fig.  5 

v 1965a  Kiaerograptus  kiaeri  (Monsen);  Erdtmann,  pp.  106-107,  pi.  2,  figs  1 and  2;  pi.  3,  fig.  4. 

Name.  Latin  supremus , uppermost,  indicating  its  position  as  the  last  of  the  fully  bithecate  species  in  the 
Krapperup  core. 

Material.  46  specimens,  of  which  44  come  from  the  1 5 1 -96—144-57  m level  of  the  Krapperup  core  and  2 from 
the  Toyen  section,  Oslo  (both  found  on  PMO  73.652;  illustrated  by  Erdtmann  1965a).  Holotypc  LO  5970T 
(Text-fig.  5a),  paratype  LO  597 1 1. 

Associated  species.  ?Trograptus  sp.,  P.  onubensis , A.  murrayi. 

Stratigraphic  range.  K.  supremus  and  A.  murrayi  Zones. 

Diagnosis.  Rhabdosome  composed  of  two  undivided  declined  stipes.  Proximal  development 
comparable  to  isograptid  type.  Bithecae  present  throughout  stipes  but  sometimes  not  regularly 
alternating.  Length  of  sicula  l-7-2-0mm,  stipe  width  0-8-1 T mm,  12-13  thecae  in  10  mm, 
divergence  of  stipes  115-140°. 

Description.  The  species  is  a typical  anisograptid,  with  bithecae  developed  at  most  or  all  available  nodes  (with 
possible  reductions  in  the  stratigraphically  youngest  specimens  - no  pyritized  specimens  are  available  above 
147-66  m).  The  proximal  development  type  resembles  the  isograptid  development,  i.e.  th  1 2 is  dicalycal.  As  seen 
in  Text-figure  5 a,  though,  theca  22  emerges  from  the  sicula-facing  side  of  th  l2,  indicating  that  the  triad 
(alternate)  budding  mechanism  operates  already  in  this  position.  Both  sinistral  and  dextral  forms  are  found 
(compare  Text-fig.  5a  with  5b).  A sclerotized  stolon  system  has  not  been  observed:  a relief  specimen  (now 
unfortunately  lost)  from  the  Krapperup  core,  filled  with  clear  calcite,  appeared  'empty'  inside.  The  sicula  is 
tube-like,  I -7—2-0  mm  long  and  0-3-0-45  mm  wide  at  the  aperture,  depending  on  the  degree  of  compression.  The 
first  bud  emerges  approximately  0-25  mm  from  the  apex  of  the  sicula.  The  stipes  show  typical  triad  budding, 
i.e.  the  autothecae  are  seen  to  emerge  alternately  from  opposite  sides  of  the  stipe.  The  first  bi  theca  of  each  stipe 
(as  well  as  the  sicular  bitheca)  seems  to  occur  on  the  obverse  side.  Thecal  length,  including  stolothecae,  can  be 
estimated  at  2 mm.  Thecal  width  at  the  aperture  is  0-5  mm,  sometimes  slightly  more  in  flattened  specimens.  The 
free  ventral  part  of  the  thecae  is  somewhat  curved,  especially  if  the  proximal  part  of  the  theca  is  more 
completely  pyritized  than  the  distal  part  (see  Text-fig.  5 a).  The  inclination  of  the  distal  parts  of  thecae  varies 
from  30°  to  45°  depending  on  the  degree  of  compression.  There  are  12-13  thecae  in  10  mm.  The  thecal  overlap 
is  difficult  to  estimate  due  to  the  triad  budding:  the  thecae  do  not  bud  dorsally,  but  laterally.  In  regular  triad 
budding,  the  budding  point  of  every  second  theca  is  on  the  unexposed  side  of  the  specimen.  Such  a theca  will 
be  seen  only  as  a wedge  between  the  preceding  and  the  following  theca  (see  Text-figs  4 and  5).  The  bithecae 
are  about  0-4  mm  long  and  0-1-0-15  mm  wide.  They  do  not  reach  the  aperture  of  the  previous  autotheca.  Text- 
figure  5b  shows  a stipe  with  irregular  triad  budding:  the  bithecae  associated  with  th  22  and  42  are  on  the  obverse 
side,  whereas  that  associated  with  th  62  is  on  the  reverse  side.  The  profile  stipe  width  is  0-8-0-9  mm  in  relief 
specimens,  and  0-9—1  - 1 mm  in  flattened  ones.  The  stipe  divergence  angle  is  115-140°. 

Remarks.  Within  the  studied  area,  the  species  was  found  only  in  the  Krapperup  core  and  the 
Toyen  section  in  Oslo  (Erdtmann  1965a).  From  the  latter  area  only  two  specimens  from  a shale 
band  at  the  very  top  of  the  Ceratopyge  Limestone  unit  were  found.  This  limestone  is  considered  as 
the  top  of  the  Tremadoc  in  Scandinavia.  Most  or  all  of  it  is  younger  than  the  youngest  Tremadoc 
beds  present  in  the  type  area.  Because  the  Krapperup  core  lacks  the  limestone,  it  is  a little  difficult 
to  correlate  the  two  occurrences  of  the  species.  On  circumstantial  evidence  (Fagelsang  core),  the 
Krapperup  specimens  are  somewhat  younger. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


293 


text-fig.  5.  Kiaerograptus  supremus  sp.  nov.  from  the  Krapperup  core,  a,  holotype,  LO  5970T,  a dextral 
specimen  in  full  relief,  151  -46—15 1-50  m.  b,  LO  597 1 1.  a sinistral  specimen  in  low  relief,  with  irregular  triad 
budding,  150-13-  150- 17  m.  Both  specimens  drawn  under  vertical  light. 


The  specimens  found  in  the  Krapperup  core  are  mostly  rather  small,  the  longest  stipe  seen 
consisting  of  16  thecae  (Text-fig.  5 b),  whereas  an  average  stipe  consists  of  only  3-6  thecae.  On  the 
whole,  the  beds  with  K.  supremus  are  fairly  poor  in  graptolites,  at  least  those  well  enough  preserved 
for  identification.  A.  murrayi  appears  in  the  higher  part  of  the  range  of  K.  supremus. 

K.  supremus  seems  most  closely  related  to  K.  klotsehichini  (Obut,  1961 ).  This  species  was  referred 
to  Didymograptus,  but  the  original  illustration  (Obut  1961,  pi.  1,  fig.  7,  7 a)  shows  indications  of  triad 
budding  along  the  stipes.  The  measurements  of  that  species  are  close  to  those  of  K.  supremus , except 
for  a shorter  sicula  (but  the  illustration  gives  the  impression  of  a longer  sicula  than  mentioned  in 
the  description)  and  a slightly  narrower  final  stipe  width.  K.  klotsehichini  was  found  in  clay  shales 
in  the  southern  part  of  the  Ural  Mountains.  Apparently  it  was  not  associated  with  any  other  species 
and  its  precise  age  is  unknown.  ? Didymograptus  sp.  Bulman,  1954,  is  probably  the  oldest 
Kiaerograptus  species  so  far  known,  found  at  a rather  low  level  of  the  Dictyonema  Shale  in  the  Oslo 
region ; it  has  an  outline  fairly  close  to  that  of  K.  supremus.  It  differs  mainly  in  having  a longer  sicula, 
a slightly  narrower  final  width,  and  stipes  that  distally  become  nearly  horizontal.  Bulman  (1954, 
p.  36)  noted  that  there  was  no  trace  of  bithecae  or  stolothecae,  but  the  material  is  totally  flattened, 
thus  making  it  impossible  to  see  such  details.  Both  K.  klotsehichini  and  ? Didymograptus  sp.  are 
known  only  from  a few  specimens,  so  it  can  be  supposed  that  only  a part  of  the  full  range  of  variation 
has  been  revealed.  Two  other  species,  K.  kicieri  (Monsen,  1925)  and  K.  quasimodo  Rushton,  1981, 
show  a great  inherent  variation.  I have  studied  the  material  of  K.  kiaeri , 470  specimens,  that  formed 
the  basis  of  the  publication  by  Monsen  (1925),  and  among  these  specimens  the  variation  in,  for 
example,  stipe  attitude,  number  of  thecae  in  10  mm,  and  the  number  of  thecae  with  isolated  distal 
parts  is  such  that  the  end  members  of  the  variation  would  hardly  have  been  recognized  as  belonging 
to  the  same  species,  were  it  not  for  all  the  intermediate  specimens.  The  excellently  preserved  material 
of  K.  kiaeri  described  by  Spjeldnaes  (1963)  shows,  in  addition  to  this  variation,  at  least  three 
successive  bithecae  on  the  same  side  of  the  stipe  (see  Text-fig.  4d)  - a type  of  irregularity  found  also 
in  K.  supremus.  K.  quasimodo  resembles  K.  kiaeri  in  the  variation  of,  for  example,  stipe  attitude  and 


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distal  isolation  of  thecae,  but  also  has  a variable  number  of  stipes  (which  is  comparatively  rare  in 
K.  kiaeri  - less  than  2%);  sometimes  stipes  are  'aborted’  after  their  first  theca  (see  Rushton  1981, 
figs  2 and  3).  K.  quasimodo  also  has  occasional  second-order  branching  close  to  the  sicula,  giving 
three-stiped  specimens.  Compared  with  these  two  species,  K.  supremus  has  differently  shaped 
bithecae,  a more  constant  and  lower  stipe  divergence  angle,  more  rigid  stipes,  and  apparently  no 
thecae  with  isolated  distal  parts.  The  stipes  also  diverge  from  the  sicula  closer  to  its  aperture.  I 
interpret  the  latter  three  characters  as  more  advanced,  probably  indicating  that  K.  supremus  comes 
from  a higher  stratigraphical  level. 


Genus  araneograptus  Erdtmann  and  VandenBerg,  1985 

Type  species.  Dictyonema  macgillivrayi  nom.  nov.  T.  S.  Hall,  1897  (=  Dictyonema  grande  T.  S.  Hall,  1891 ; non 
D.  grandis  Nicholson,  1873). 

Diagnosis  (taken  from  Erdtmann  and  VandenBerg  1985). ' Rhabdosome  siculate,  biradial,  produced 
by  dichotomous  division  (similar  to  Clonograptus ),  generally  at  steadily  increasing  intervals,  to 
eighth  or  ninth  order  [or  possibly  more]  (usually  fourth  to  sixth);  adjacent  branches  connected  by 
more  or  less  regularly  spaced  dissepiments;  autothecae  in  proximal  portions  denticulate  with 
concave  ventral  margins  and  of  moderate  inclination;  bithecae  not  observed.  Juvenile  specimens,  up 
to  the  third-order  dichotomy,  cannot  be  assigned  to  a particular  species,  because  of  their  identical 
morphology  and  structural  development.’ 

Remarks.  The  absence  of  bithecae  in  the  type  species  cannot  be  considered  proven  on  the  basis  of 
the  Australian  material  used  by  Erdtmann  and  VandenBerg,  since  this  material  is  completely 
flattened  and  cannot  possibly  reveal  such  characters.  For  this  reason  I leave  Araneograptus  with  the 
Anisograptidae.  Also  the  biradiality  of  the  rhabdosome  is  not  proven  beyond  doubt.  All  the 
illustrated  details  of  proximal  ends  (Erdtmann  and  VandenBerg  1985,  fig.  6a-c)  show  an 
asymmetry  which  could  be  interpreted,  instead,  as  three  primary  stipes.  If  this  is  the  case,  the  genus 
is  a junior  synonym  of  Rhabdinopora  Eichwald. 


Araneograptus  murrayi  (J.  Hall,  1865) 

Text-figs  6,  7,  ? 1 8 c 

1865  Dictyonema  Murrayi  J.  Hall,  pp.  138-139,  pi.  20,  figs  6 and  7 [photographs  seen], 

1865  Dictyonema  quadrangularis  J.  Hall,  p.  138,  pi.  20,  fig.  5. 

1873  Dictyonema  grandis  Nicholson,  pp.  134-136,  fig.  1. 

v 1937  Dictyonema  cf.  murrayi  J.  Hall;  Monsen,  pp.  89-92,  pi.  11,  fig.  2. 

1982  Dictyonema  murrayi  J.  Hall;  Mu  et  al.,  p.  295,  pi.  73,  fig.  1. 

1982  Dictyonema  quadr angular e J.  Hall;  Mu  et  al.,  p.  295,  pi.  73,  figs  2-4. 

1982  Dictyonema  maximum  Xu  sp.  nov.;  Mu  et  al.,  pp.  295-296,  text-fig.  101,  pi.  73,  figs  5-7. 

1982  Dictyonema  ziyangense  Xu  sp.  nov.;  Mu  et  al.,  p.  296,  pi.  74,  fig.  3. 

1985  Dictyonema  pulchellum  T.  S.  Hall;  Rushton,  p.  332,  figs  1 and  2. 

1985  Dictyonema  sp.  Rushton,  p.  332,  figs  3 and  4. 

1987  Araneograptus  murrayi  (J.  Hall);  Gutierrez  Marco  and  Acenolaza,  pp.  325-330,  pi.  I 
v 1988  ‘ Dictyonema ’ cf.  yaconense  Turner;  Molyneux  and  Rushton,  pp.  65-66,  fig.  8. 

Lectotype.  GSC  962 a,  J.  Hall’s  ( 1865)  pi.  20,  fig.  7;  Text-fig.  6 herein;  designated  lectotype  by  Gutierrez  Marco 
and  Acenolaza  (1987). 

Material.  From  the  Krapperup  core  ( 148 . 22-109 . 86  m),  c.  30  surfaces  (each  30  cm2)  with  1-  > 5 specimens  of 
different  sizes,  ranging  from  juveniles  to  fragments  of  giants.  The  species  is  most  common  in  the  lower  part  of 


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295 


its  range,  up  to  136-69  mm.  At  141  m the  species  is  very  common,  forming  layers  each  a couple  of  millimetres 
thick. 

The  species  is  absent  at  Mt  Hunneberg,  and  only  a few  specimens  have  been  found  in  the  Oslo  region,  all 
except  one  slab  from  the  Slemmestad  area:  PMO  58.967  from  the  T.  phyllograptoides  Zone  (more  probably 
lower)  at  Galgeberg  (east-central  Oslo),  a large  specimen  figured  by  Monsen  (1937),  associated  with  a 
juvenile;  PMO  137  from  Gjeitungholmen,  Slemmestad,  allegedly  from  the  upper  Tremadoc  Ceratopyge 
Shale;  PMO  108.568,  108.569,  108 . 572  - together  containing  6 specimens  (of  which  3 are  juveniles)  from 
0-5-10  m above  the  Ceratopyge  Limestone  at  Slemmestad  crossroads;  PMO  1 12.967+ 1 12.969, 
PMO  1 12.969+  1 12.966,  two  relatively  large  specimens  from  Prestengveien,  Slemmestad;  and  PMO  120.751, 
three  specimens  from  21-70  m at  the  new  standard  section  (=4-1  m above  the  Ceratopyge  Limestone),  central 
Slemmestad. 

Associated  species.  K.  supremus , H.  copiosus,  T.  krapperupensis , horizontal  tetragraptids  Cquadribrachiatus’- 
type),  three-stiped  extensiform  tetragraptids,  Didymograptus  sp.  1,  P.  antiquus , P.  elongatus , P.  tenuis. 

Stratigraphic  range.  A.  nmrrayi  to  T.  phyllograptoides  Zones,  possibly  also  lower  and  higher.  Maximum 
abundance  in  the  A.  nmrrayi  Zone. 

Diagnosis  (based  on  the  Scandinavian  material  and  Gutierrez  Marco  and  Acenolaza  (1987)). 
Rhabdosome  conical,  mostly  subtending  an  angle  of  60-75°  when  flattened,  angle  decreasing 
distally  in  big  specimens.  Meshwork  normally  has  3-4  stipes  in  10  mm,  and  2-3  dissepiments  in 
10  mm,  but  the  total  variation  ranges  well  outside  these  limits.  The  shape  of  the  meshes  is  variable, 
from  rectangular  to  oval.  The  lateral  stipe  width  is  over  1 mm,  the  thickness  of  the  dissepiments  is 
variable.  The  maximum  length  of  the  rhabdosome  is  unknown,  but  at  least  30  cm. 

Description.  Not  much  is  known  about  the  details  of  proximal  growth  pattern  of  the  species.  A few  immature 
specimens  have  been  found  at  different  levels  in  the  Krapperup  core.  A couple  of  these  could  possibly  support 
a biradiate  origin  of  the  rhabdosome,  while  others  seem  asymmetrical  enough  to  indicate  a triradiate  origin. 
The  sicula  is  L8-  1-9  mm  long  where  seen  in  full  but  presumably  somewhat  longer,  perhaps  up  to  2-5  mm,  in 
some  more  mature  specimens.  A very  short  nema  of  normal  thickness  is  seen  in  a couple  of  the  immature 
specimens.  No  specimen  is  well  enough  preserved  to  show  beyond  doubt  a biradiate  origin  or  any  details  of 
proximal  development.  At  two  levels  (those  of  Text-figs  17  and  18),  pyritized  immature  specimens  of  various 
species  occur.  Some  of  these  are  pendent  and  may  belong  to  A.  nmrrayi  but,  due  to  the  lack  of  dissepiments, 
this  cannot  be  proved  unequivocally.  All  pendent  forms  seen  in  obverse  view  have  a sicular  bitheca.  One  of  the 
specimens  seen  in  reverse  view  (Text-fig  18c),  shows  a dicalycal  theca  l2  and  a two-stiped  origin.  It  apparently 
lacks  plaited  thecal  structure.  In  some  of  the  slightly  larger  specimens  (Text-fig.  7f,  h)  the  sicula,  and 
sometimes  also  more  of  the  proximal  region,  is  covered  with  cortical  tissue,  extending  on  to  the  nema,  which 
is  then  up  to  more  than  1 mm  thick.  A couple  of  thecae  are  seen  in  partial  profile  view  in  one  of  the  immature 
specimens,  giving  an  estimate  of  11-5  thecae  in  10  mm.  The  thecae  seem  to  be  straight  tubes  of  normal 
dichograptid  appearance.  On  the  other  hand,  a Moroccan  specimen  (Text-fig.  7b)  shows  a few  thecae  in  relief 
which  are  very  denticulate,  the  distal  part  of  the  ventral  side  being  almost  at  right  angles  to  the  dorsal  margin 
of  the  stipe.  This  high  angle  could,  however,  be  due  to  distortion.  The  thecae  number  about  12-5  in  10  mm  in 
this  specimen.  The  difference  in  thecal  shape  between  the  two  specimens  can  be  explained  in  different  ways: 
either  the  thecal  shape  changes  along  the  rhabdosome,  or  the  slightly  oblique  position  of  the  thecae  in  the 
Scandinavian  specimens  obscures  their  true  shape.  Another  possibility  is,  of  course,  that  there  is  more  than  one 
species  which  cannot  be  distinguished  on  the  basis  of  cone  shape  and  mesh  pattern  alone.  Ruedemann  (1947, 
p.  171 ) commented  on  the  thecae  thus:  ‘Thecae  numbering  9-10  in  10  mm;  apparently  with  acute  extensions 
of  apertural  margins.’  Rushton  (1985,  fig.  2c)  showed  elongate  thecae  with  high  overlap  and  high  distal 
inclination. 

Normally,  only  the  dorsal  side  of  the  stipes  is  seen,  since  this  is  the  outward-facing  side  of  the  cone  and  also 
represents  the  surface  most  easily  exposed  by  splitting.  The  lateral  stipe  width  is  mostly  1-2—1  -5  mm  in  flattened 
specimens.  Specimens  with  some  relief  often  have  thinner  stipes,  down  to  10  mm.  The  stipe  width  of  immature 
specimens  is  sometimes  as  low  as  0-6-0-7  mm.  The  dissepiments  are  rather  regularly  spaced  within  a specimen 
(closer  in  the  proximal  part,  though),  but  the  number  of  dissepiments  per  length  unit  varies  markedly  from  one 
specimen  to  another,  from  about  4 in  10  mm  down  to  1-5.  The  average  density  is  about  2-3  dissepiments  in 
10  mm.  Also  the  stipe  density  varies  between  specimens.  This  variation  is  due  to  the  frequency  of  dichotomies 


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text-fig.  6.  GSC  962a,  lectotype  slab  of  A.  murrayi  (J.  Hall)  containing  three  specimens,  x 1.  a,  specimen  of 
quadrangularis  type  with  short  meshes  and  relatively  broad  dissepiments,  b,  lectotype.  c,  specimen  with  short 
meshes  and  relatively  thin  dissepiments.  The  specimens  are  associated  with  numerous  rhabdosomes  of 

Clonograptus  rigidus. 

(see  Text-fig.  7 c)  and  the  angle  of  the  cone.  There  are  normally  about  3-5-4  stipes  in  10  mm,  but  the  total 
variation  ranges  from  3 to  5.  The  variation  in  stipe  and  dissepiment  density  gives  a marked  variation  in  size 
and  shape  of  the  meshes.  Another  factor  influencing  this  is  the  thickness  and  shape  of  the  dissepiments.  The 
meshes  can  thus  be  square,  rectangular,  nearly  circular,  or  oval.  The  thickness  of  the  dissepiments  varies  from 
considerably  thicker  to  noticeably  thinner  than  the  stipes,  but  in  most  specimens  they  are  of  about  the  same 
thickness  as  the  stipes.  The  dissepiments  are  sometimes  uniformly  thick,  in  others  thinner  in  their  middle  part. 
Secondary  cortical  additions  to  the  stipes  and  dissepiments  can,  under  special  circumstances,  almost  fill  out  the 
meshes  (Text-fig.  7e).  The  formation  of  dissepiments  seems  to  have  been  very  regular,  these  being  inserted  in 
every  second  or  third  position  at  the  same  time  (or  rather,  the  sariie  distance  from  the  sicula),  so  that  the  meshes 
form  diagonal  rows  across  the  specimen  (see  Text-fig.  7a,  c).  This  pattern  is  disturbed  where  dichotomies 
occur.  These  are  relatively  frequent  in  proximal  parts  (see  Text-fig.  7f)  but  rare  in  the  distal  part  of  large 
specimens.  Text-figure  7c  shows  two  zones  of  stipe  division,  both  apparently  induced  by  irregularities  in  the 
mesh  pattern.  The  left  zone  compensates  for  the  loss  of  a stipe  (t  in  the  figure),  the  right-hand  one  seems  to 
compensate  for  a deflection  to  the  right  of  one  stipe,  as  seen  by  the  very  small  mesh  to  the  right  of  this  stipe 
slightly  more  proximally  than  the  point  of  dichotomy  (this  interpretation  seems  more  probable  than  that  a stipe 
division  was  planned  for).  In  both  cases  the  dichotomies  compensating  a disturbance  are  paired,  followed  by 
an  additional  dichotomy  slightly  later.  Paired  dichotomies  were  illustrated  also  by  Rushton  (1985,  fig.  4). 

A couple  of  relief  specimens  (see  Text-fig.  7 d)  have  what  appears  to  be  later  additions  attached  on  the  outside 
of  the  rhabdosome,  pouch-like  ‘balconies’  that  join  the  stipes  on  their  dorsal  side.  They  do  not  seem  to  form 
part  of  the  normal  dissepiments.  Their  function  is  likely  to  have  been  to  direct  water  currents  through  the 
rhabdosome  meshwork.  A distal  end  fragment  (Text-fig.  7a)  shows  that  dissepiments  are  present  at  normal 
frequency  to  the  very  distal  end  of  the  stipes,  i.e.  they  are  produced  as  the  stipe  grows.  Further,  the  distalmost 
dissepiments  have  full  width,  but  the  2-3  last  produced  of  them  seem  to  be  less  dense.  This  may  explain  the 
apparent  lack  of  strength,  leading  to  the  disruption  shown  in  Text-figure  7 a. 

The  angle  of  the  cone  is  normally  60-75°,  but  in  a couple  of  cases  angles  as  low  as  40-50°  have  been  observed. 
As  seen  from  some  very  large  Spanish  specimens,  the  angle  of  the  cone  decreases  distally.  The  angles  of  the 
larger  Scanian  specimens  were  impossible  to  measure,  since  the  drillcore  surfaces  contain  only  small  fragments 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


297 


osliStes 


#o§Ws»w 

MM; 


text-fig.  7.  Araneograptus  murrayi  (J.  Hall).  Black  dots  in  rhabdosomes  indicate  the  positions  of  stipe 
divisions,  a,  LO  5972t,  Krapperup  core,  137-70  m,  the  distal  end  of  a large  specimen;  stippling  indicates  not 
fully  corticized  dissepiments,  dashed  outlines  represent  superposed  phyllocarids.  b.  PMO  120.752,  detail  of  a 
Moroccan  specimen  showing  thecae  in  some  relief,  c,  LO  5973t,  Krapperup  core,  137-60  m,  part  of  a large 
specimen  with  relatively  elongate  meshes  and  two  zones  of  branching;  + represents  the  termination  of  a stipe. 
d,  PMO  112.966,  Slemmestad,  detail  of  a specimen  with  pouch-like  ‘balconies',  e,  PMO  58.967  (=  Monsen 
1937,  pi.  11,  fig.  2),  Galgeberg,  Oslo,  detail  showing  cortical  overgrowth  of  a mesh,  f,  PMO  137,  upper 
Tremadoc  (?),  Gjeitungholmen,  Slemmestad,  a specimen  with  the  proximal  part  covered  by  cortical  tissue 
(stippling).  G,  LO  5974t,  Krapperup  core  147-66-147-72  m,  a specimen  without  cortical  overgrowth  of  the 
proximal  part,  and  possibly  indicating  a triradiate  origin,  h,  LO  5975t,  Krapperup  core  140-30  m,  a specimen 

with  cortical  overgrowth  of  sicula  and  nema. 


of  rhabdosomes.  The  maximum  number  of  stipe  dichotomies  is  unknown  but.  judging  from  the  very  low 
number  of  branchings  on  the  drillcore  surfaces,  the  rhabdosomes  must  have  been  very  big,  with  a cone  length 
of  perhaps  more  than  20  cm. 

Remarks.  The  large  Scanian  specimens  are  closely  similar  to  the  specimen  figured  by  J.  Hall  (1865, 
pi.  20,  fig.  7),  except  that  their  dissepiments  are  on  the  average  somewhat  thicker.  Hall,  according 
to  the  figured  material  of  Dictyonema  murrayi , allowed  a certain  variation  in  the  number  of 
dissepiments  per  length  unit,  the  specimen  in  plate  20,  figure  6 having  a dissepiment  spacing  equal 
to  that  of  D.  quadrangularis  figured  on  the  same  plate.  Hall  seems  to  have  found  the  thickness  of 
the  dissepiments  more  important  than  their  spacing.  But,  on  the  type  slab  GSC  962 n,  containing 
plate  20,  figure  7 and  two  additional  specimens  (Text-fig.  6),  all  three  shapes  co-occur  on  one 
surface,  indicating  their  probable  conspecificity. 

Gutierrez  Marco  and  Acenolaza  (1987)  also  synonymized  D.  yaconense  from  South  America  and 
Nyssenia  zemmourensis  from  northern  Africa,  as  well  as  some  variously  named  European  finds,  with 
A.  murrayi.  Interestingly,  they  noted  that  the  descriptions  of  different  species  fitted  different  parts 
of  one  rhabdosome.  They  hesitated  to  synonymize  A.  pulchellus,  although  they  noted  that  in  some 


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characters  the  two  species  were  partly  overlapping.  Their  main  argument  was  that  no  specimen  of 
A.  pulchellus  of  the  size  of  the  larger  A.  murrayi  specimens  has  ever  been  found.  Although  they  did 
not  regard  D.  grandis  Nicholson  as  a junior  synonym,  I suggest  that  it  is.  According  to  Nicholson 
(1873),  D.  grandis  differs  from  D.  murrayi  by  having  conical  form,  more  frequent  bifurcation,  and 
meshes  wider  than  long.  The  first  two  differences  are  easily  explained  by  Nicholson’s  specimen  being 
the  proximal  part  of  a rhabdosome  and  Hall’s  specimens  more  distal  fragments.  The  third 
difference,  the  shape  of  the  meshes,  can  be  explained  by  tectonic  distortion,  coupled  with  more 
closely-spaced  dissepiments  in  the  proximal  part  of  the  rhabdosome.  Both  J.  Hall’s  and  Nicholson’s 
types  derive  from  Levis,  Quebec. 

A.  murrayi  has  a world-wide  distribution,  including  Europe  (Scandinavia,  Great  Britain, 
Germany,  France,  Spain),  northern  Africa,  eastern  North  America,  South  America  (as  D. 
yaconense;  Argentina,  Bolivia),  and  NW  China.  The  species  was  listed,  but  not  illustrated,  from  the 
Taimyr  area  of  the  Soviet  Union  by  Obut  and  Sobolevskaya  (1962).  A more  detailed  account  of  the 
distribution  is  given  by  Gutierrez  Marco  and  Acenolaza  (1987).  In  addition,  the  possibly  conspecific 
A.  pulchellus  is  found  in  Australasia  and  western  Canada.  Both  species  seem  to  be  restricted  to  a 
relatively  narrow  stratigraphical  interval,  corresponding  to  the  Australasian  stage  La  2,  and  in  some 
cases  the  basal  part  of  La  3. 


Suborder  dichograptina  Lapworth,  1873 

Diagnosis  (from  Fortey  and  Cooper  1986;  emended  by  Lindholm  and  Maletz  1989).  Graptoloids 
lacking  bithecae  along  the  stipes,  and  without  virgella. 

Remarks.  The  diagnosis  by  Fortey  and  Cooper  has  been  emended  to  incorporate  in  the 
Dichograptina  the  anisograptid/dichograptid  intermediary  forms  with  a sicular  bitheca,  but 
without  bithecae  along  the  stipes.  Since  the  loss  of  bithecae  apparently  occurred  in  different  lineages 
during  a relatively  short  period  of  time,  the  Dichograptina,  like  the  Anisograptidae,  will  be  a 
paraphyletic  group,  no  matter  where  the  boundary  between  the  two  groups  is  drawn  (however,  see 
remarks  on  the  Anisograptidae,  p.  291). 


Superfamily  dichograptacea  Lapworth,  1873 

Diagnosis  (from  Fortey  and  Cooper  1986;  slightly  emended  by  Lindholm  and  Maletz  1989). 
Dichograptinids  lacking  isograptid  symmetry,  number  of  orders  of  dichotomy  in  rhabdosome  not 
limited. 

Remarks.  The  diagnosis  by  Fortey  and  Cooper  has  been  emended  to  include  forms  which 
apparently  have  unlimited  capacity  for  dichotomy,  e.g.  the  genus  Clonograptus. 


Family  dichograptidae  Lapworth,  1873 

Diagnosis  (from  Fortey  and  Cooper  1986).  Dichograptaceans  lacking  prothecal  folds  and 
sigmagraptine  proximal  end. 


Genus  hunnegraptus  gen.  nov. 


Name.  From  Ml  Hunneberg. 


Type  species.  Hunnegraptus  copiosus  gen.  et  sp.  nov. 


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Diagnosis.  Dichograptids  with  a didymograptid  proximal  part  and  two  or  more  orders  of  stipes 
produced  by  dichotomous  division;  first-order  stipes  extensiform  or  declined,  normally  consisting 
of  approximately  5-25  thecae.  Sicula  tube-like;  a sicular  bitheca  present  at  least  in  the  type  species. 
Proximal  development  isograptid,  sinistral  and  dextral  forms  co-occurring.  Thecae  straight  tubes  of 
dichograptid  type,  no  bithecae  observed  along  stipes.  Secondary  cortical  thickening  may  be  present; 
possible  stipe  regeneration  in  gerontic  specimens. 

Species  included.  H.  copiosus  sp.  nov.,  H.  tjernviki  sp.  nov.,  H.  robustus  sp.  nov.,  and  provisionally  H.  novus 
(Berry,  1960),  H.  gulinensis  (Wang,  1981),  H.  minor  (Wang,  1981 ),  H.  sichuanensis  (Wang,  1981 ),  H.  sp.  (Wang, 
1981).  Wang’s  taxa  are  probably  synonyms. 

Remarks.  The  Scandinavian  specimens  of  the  genus  are  here  divided  into  three  contemporaneously 
occurring  species.  However,  it  is  possible  that  they  all  belong  to  one  species,  representing  different 
growth  stages.  Unfortunately,  though,  the  ’mature’  and  ‘gerontic’  specimens  are  very  rare 
compared  to  the  ‘adolescents’  and  a continuous  spectrum  of  variation  cannot  be  proven  based  on 
the  available  material.  Therefore  the  three  species  H.  copiosus  (abundant,  and  the  only  one  of  the 
three  found  as  immature  specimens;  ‘young  stage’),  H.  tjernviki  (less  common;  ‘mature  stage’), 
and  H.  robustus  (rare;  ‘gerontic  stage’)  are  here  described  as  separate  entities.  If  their  synonymy  can 
be  proved,  the  name  H.  copiosus  takes  precedence.  Synonymy  would  imply  that  all  thecae  kept 
growing  through  the  entire  life  of  the  colony  (cf.  Williams  and  Stevens  1988),  or  until  the  apertures 
were  covered  by  cortex.  The  ‘gerontic’  rhabdosomes  are  too  flattened  to  prove  that  such  ‘choking’ 
with  cortex  took  place,  but  nearly  all  specimens  of  H.  robustus  have  irregularly  placed  thin  lateral 
stipes,  as  thin  as  those  of  the  other  two  species.  These  stipes  are  connected  to  the  main  body  of  the 
rhabdosome  by  the  cortex,  and  thus  cannot  be  superimposed  stipes  belonging  to  other  specimens. 
They  do  not  influence  the  direction  or  thickness  of  the  main  stipes.  They  appear  to  represent  a 
rejuvenation  of  the  colony,  extra  stipes  being  inserted  later  than  the  surrounding  branches.  This 
could  be  to  compensate  for  zooids  no  longer  active  in  that  part  of  the  rhabdosome.  These  stipes  are 
probably  not  metacladia,  and  I have  seen  no  report  of  comparable  stipe  formation  in  any  other 
graptoloid. 

The  Scandinavian  occurrences  are  restricted  to  the  H.  copiosus  Zone,  the  zone  directly  underlying 
the  Tetragraptus  phyUograptoides  Zone.  Provisionally  included  in  Hunnegraptus  is  H.  novus  (Berry, 
1960),  which  has  a sicular  bitheca  but  normally  no  bithecae  along  the  stipes.  This  taxon  is  probably 
older  than  the  Scandinavian  occurrences,  however,  since  it  is  reported  to  co-occur  with  Anisograptus 
(Berry  1960).  Provisionally  included  are  also  Kiaerograptusl  gulinensis,  K.l  sp.,  Adelograptus  minor , 
and  A.  sichuanensis , all  described  by  Wang  (1981 ) from  probable  Late  Xinchangian  beds  of  Sichuan, 
central  China.  All  of  these  are  most  likely  conspecific,  the  amount  of  variation  among  them  being 
smaller  than  that  within  the  type  species  of  Hunnegraptus.  Multiramous  species  with  dichograptid 
thecae  and  prolonged  first-order  stipes  have  also  been  described  from  Spain  (Gutierrez  Marco  1982, 
1986,  pp.  290-304)  and  Czechoslovakia  (Kraft  and  Mergl  1979).  The  material  from  Spain  is  of 
Early  Hunneberg  age,  and  the  associated  fauna  contains  i.a.  A.  murrayi.  The  age  of  the  Czech 
material  is  uncertain.  The  relationship  of  these  species  to  Hunnegraptus  is  not  clear. 

The  genus  is  presumably  most  closely  related  to  Clonograptus , in  which  first-order  stipes  may  be 
prolonged,  e.g.  in  the  type  species,  C.  rigidus.  The  sicular  bitheca  seen  in  H.  copiosus  is  also  found 
in  Clonograptus  milesi , and  probably  also  in  the  type  species  (Lindholm  and  Maletz  1989). 
Regenerated  stipes  of  Hunnegraptus  type  are  unknown  in  Clonograptus.  The  latter  fact  has 
convinced  me  that  the  distinction  between  the  two  taxa  should  be  on  a generic,  rather  than 
subgeneric,  level. 


Hunnegraptus  copiosus  gen.  et  sp.  nov. 

Text-figs  8a-f  and  18f,  ?h,  j 

1987  Dichograptid  sp.  1 Maletz,  p.  136,  text-fig.  44:9;  10,  pi.  5,  figs  1 and  2. 

p 1987  Dichograptid  sp.  2 Maletz,  pp.  136-137,  text-fig.  44:3?,  5-8. 


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Name.  Latin  copiosus , abundant,  refers  to  the  abundance  of  the  species  in  all  sections. 

Material.  736  specimens,  of  which  1 1 1 come  from  east-central  Oslo  (Toyen,  3-55-3-68  m above  the  Ceratopyge 
Limestone,  and  Galgeberg),  213  from  various  localities  in  the  Slemmestad  area,  165  from  Storeklev,  Mt 
Hunneberg,  and  247  from  the  Krapperup  core  (132-73-117-00  m).  Except  for  Krapperup,  the  stratigraphic 
range  is  rather  limited,  with  specimens  collected  from  a single  horizon  in  a section  or,  as  in  Storeklev  and  the 
new  standard  section  in  central  Slemmestad,  from  a relatively  thin  band  (1-4- 1-8  m and  4-6-5-6  m above  the 
Ceratopyge  Limestone,  respectively).  The  holotype  is  found  on  PMO  58.969  from  Galgeberg,  central  Oslo 
(Text-fig.  8e,  f);  the  paratypes  are  LO  5976t-5979t,  LO  6090t,  LO  6094t,  and  PMO  108.599  (localities  given 
in  figure  captions).  The  species  is  very  common  and  is  found  on  most  slabs  within  its  range,  mostly  as  two- 
stiped,  didymograptid-like,  specimens. 

Associated  species.  H.  tjernviki,  H.  robustus , A.  murrayi , Clonograptus  s.s.  sp.  indet.,  T.  longus , T.  cf. 
krapperupensis,  narrow-  and  broad-stiped  horizontal  tetragraptids  Cquadribrachiatus’-type),  three-stiped 
extensiform  tetragraptids,  gen.  et  sp.  indet.  1,  Didymograptus  sp.  2,  Isograptus  sp.,  P.  antiquus , P.  pritchardi , 
P.  elongatus , P.  tenuis , P.  cf.  rams. 

Stratigraphic  range.  H.  copiosus  Zone. 

Diagnosis.  Didymograptid  proximal  part  and  one,  two,  or  possibly  more  orders  of  stipes.  First- 
order  stipes  normally  declined,  consisting  of  approx.  7-22  thecae  each.  Sicula  mostly  11—1-2  mm 
long,  sicular  bitheca  present.  Thecae  straight  tubes  with  a thecal  inclination  of  15-20°.  Stipe  width 
0-5-0-6  mm,  approx.  12  thecae  in  10  mm.  No  bithecae  along  stipes. 

Description.  The  sicula  is  tube-shaped,  1 -0—1  3 mm  long,  0-25  mm  wide  at  the  aperture;  and  its  distal  part  is 
inclined  towards  the  stipe2  side.  The  proximal  part  of  the  nema  is  somewhat  thickened,  like  the  cauda  (Hutt 
1974).  A slightly  curved  bitheca  is  present  on  the  obverse  side  of  the  sicula,  budding  from  th  1 1 at  mid-length 
of  the  sicula  (Text-figs  8 b,  f and  1 8 f).  The  aperture  of  the  bitheca  is  positioned  where  th  l1  bends  away  from 
the  sicula.  Theca  l1  buds  from  the  sicula  approximately  01-0-2  mm  from  its  apex.  In  early  growth  stages 
consisting  of  the  sicula  and  th  1 1 , the  sicula  and  theca  make  a more  or  less  symmetrical  pair,  with  the  bitheca 
in  a central  position.  The  proximal  development  type  is  isograptid,  theca  21  budding  from  th  l2  in  its  most 
proximal  part.  There  are  both  sinistral  and  dextral  specimens  (compare  Text-fig.  8 a with  8 d)  but  too  few  well- 
preserved  specimens  have  been  found  for  any  statistical  evaluation  of  predominance.  The  proximal  part  of  the 
protheca  is  relatively  narrow,  resulting  in  a rather  low  thecal  inclination  (15-20°).  A slight  prothecal  folding 
can  be  seen  in  pyritized  relief  specimens  (Text-fig.  8 a,  b,  d).  The  metathecae  are  simple  tubes,  straight  or  nearly 
so;  the  total  thecal  length  is  about  1-2  mm,  the  dorsoventral  thecal  width  at  the  aperture  about  0-25-0-3  mm. 
The  thecal  overlap  is  about  40-50%,  and  there  are  normally  1 1-5-13  thecae  in  10  mm  (total  range  10-5-14). 
The  profile  stipe  width  is  0-5-0-6  mm,  bithecae  are  absent  along  stipes,  both  in  their  proximal  and  distal  parts. 
The  first-order  stipes  consist  of  7-22  thecae  (observed  range)  and  make  an  angle  of  about  120-180°  (normally 
130-160°)  if  seen  in  profile  view.  A pyritized  specimen  possibly  belonging  to  the  species  (Text-fig.  1 8 H ) shows 
a first-order  stipe  consisting  of  only  3 thecae.  Stipe  division  is  dichotomous;  the  longest  second-order  stipes 


text-fig.  8.  a-h  Hunnegraptus  copiosus  sp.  nov.  a,  b,  LO  5976t  and  LO  5976  + , Storeklev  2-15-2-32  m, 
counterparts  of  a dextral  relief  specimen,  c,  LO  5977t,  Storeklev  2-32  m,  an  almost  flattened  specimen,  showing 
the  most  typical  appearance  of  the  species,  d,  PMO  108.599,  Slemmestad,  a full  relief  sinistral  specimen;  note 
the  difference  in  thecal  spacing  between  the  stipes:  associated  specimens  show  no  tectonic  distortion,  e,  f, 
holotype,  PMO  58.969,  Galgeberg,  east-central  Oslo,  a sinistral  specimen  (proximal  part  is  a mould)  with  the 
fourth  second-order  stipe  presumably  primarily  missing;  part  of  one  stipe  is  pyritized,  showing  absence  of 
bithecae;  f is  drawn  from  a latex  cast  and  shows  the  sicular  bitheca  in  low  relief.  G,  LO  5978t,  22-2  m in  the 
standard  section,  Slemmestad,  a dextral  specimen  (the  sicular  part  is  a mould),  one  of  the  bigger  specimens, 
in  a preservation  showing  the  low  degree  of  rigidity  of  the  stipes.  H,  LO  5979t,  associated  with  specimen  shown 
as  a and  b;  the  specimen  has  highly  unequal  length  of  first-order  stipes,  a,  b,  d,  f are  drawn  from  latex  casts 
under  vertical  light,  i-k,  H.  tjernviki  sp.  nov.  I,  PU  Vg  125,  Storeklev  227-230  cm,  a stipe  fragment  in  profile 
view,  j,  LO  5980t,  Grundvik,  Slemmestad,  the  longest  stipe  fragment,  showing  four  orders  of  stipes;  the 
drawing  is  a combination  of  counterparts.  K,  holotype,  PU  Vg  124,  Storeklev  227  cm. 


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seen  are  more  than  40  mm  long.  A branching  stipe  fragment  probably  belonging  to  the  species  (Text-fig.  1 8 j) 
shows  isograptid  type  branching.  No  complete  specimen  shows  more  than  two  orders  of  stipes,  but  it  cannot 
be  excluded  that  the  branching  continues.  In  one  specimen  (LR  6.  from  Storeklev)  an  'aborted'  stipe  division 
can  be  seen : part  of  a theca  projects  from  the  dorsal  side  of  a stipe,  but  the  stipe  continues  in  its  previous 
direction.  Also  the  holotype  may  have  lost  a stipe  in  the  same  way  (Text-fig.  8 e)  : no  trace  of  a fourth  second- 
order  stipe  is  seen,  but  in  this  case  the  stipe  is  bent  as  if  branching  had  occurred.  The  majority  of  the  specimens 
found  are  too  small  for  branching  to  have  occurred.  These  specimens  look  like  declined  didymograptids,  but 
relief  specimens  in  obverse  view  show  the  characteristic  sicular  bitheca.  No  marked  secondary  cortical 
thickening  has  been  observed  in  this  species.  Specimens  are  often  somewhat  flexuous.  No  gerontic  specimens 
were  found,  however,  and  the  possibility  of  cortical  thickening  at  a later  growth  stage  cannot  be  ruled  out. 

Remarks.  The  low  thecal  inclination  and  the  faint  prothecal  folding  observed  in  relief  specimens  of 
H.  copiosus  might  suggest  a relationship  with  the  Sigmagraptidae.  However,  the  proximal  part 
differs  markedly  from  that  of  the  type  species  of  Sigmagraptus  (cf.  Cooper  and  Fortey  1982,  fig.  61): 
the  length/width  ratio  of  the  sicula  is  smaller,  the  prothecal  part  of  theca  l1  is  shorter,  th  21  buds 
off  th  l2  slightly  later,  so  that  it  crosses  th  l1  instead  of  following  its  dorsal  side,  and  also  neither 
th  l1  nor  th  l2  has  the  characteristic  sharp  bend  seen  in  sigmagraptids.  Except  for  the  sicular 
bitheca,  the  proximal  structure  in  Hunnegraptus  is  normal  dichograptid.  The  presence  of  both 
sinistral  and  dextral  forms  must  be  assumed  to  be  a primitive  character  (common  among  the 
Anisograptidae). 

The  Chinese  species  described  by  Wang  (1981 ) are  all  very  similar  to  H.  copiosus.  The  illustrations 
show  a proximal  part  virtually  identical  to  that  of  H.  copiosus , and  sicular  length  and  figures  given 
for  thecal  characters  differ  insignificantly  from  those  of  that  species.  The  only  visible  difference  lies 
in  the  position  of  second-order  dichotomy,  which  is  closer  to  the  sicula  in  the  Chinese  species.  All 
the  specimens  illustrated  by  Wang  (1981)  have  one  or  two  stipe  orders,  like  H.  copiosus.  H.  novus 
(Berry,  1960)  is  known  only  as  a two-stiped  form.  Also  this  taxon  has  a thecal  shape  reminiscent 
of  H.  copiosus. 


Hunnegraptus  tjernviki  gen.  et  sp.  nov. 

Text-fig.  8i-k 

p 1987  Dichograptid  sp.  2 Maletz,  pp.  136-137,  fig.  44: 1,  2,  4;  pi.  5,  fig.  3. 

Name.  In  honour  of  Torsten  Tjernvik,  the  discoverer  of  the  Early  Hunneberg  graptolite  fauna. 

Material.  32  more  or  less  fragmentary  specimens,  of  which  1 1 are  from  Oslo,  10  from  the  Slemmestad  area, 
9 from  Storeklev,  and  2 from  Krapperup.  The  range  coincides  with  that  of  H.  copiosus.  Holotype  PU  Vg  124 
(Text-fig.  8k.)  and  paratype  PLf  Vg  125  from  Storeklev;  paratype  LO  5980t  from  Grundvik,  Slemmestad. 

Associated  species.  H.  copiosus , T.  longus , P.  antiquus. 

Stratigraphic  range.  H.  copiosus  Zone. 

Diagnosis.  Didymograptid  proximal  part  and  up  to  four  or  possibly  more  orders  of  stipes.  First- 
order  stipes  horizontal  or  slightly  declined,  consisting  of  several  thecae.  Sicula  approximately 
1-5  mm  long,  sicular  bitheca  suspected.  Thecae  straight  tubes  with  an  inclination  of  about  30°.  Stipe 
width  0-8-1 -2  mm,  about  1 T5  thecae  in  10  mm.  No  bithecae  along  stipes. 

Description.  The  species  is  known  from  fewer  specimens,  and  also  in  less  detail,  than  H.  copiosus.  Most 
specimens  consist  of  stipe  fragments  only.  The  sicula  is  about  15  mm  long;  no  specimen  is  well  enough 
preserved  to  reveal  a possible  sicular  bitheca  or  the  proximal  development.  The  thecae  are  simple  straight  tubes, 
approximately  I -4-1  -7  mm  long  and  0-4-0-5  mm  wide  at  the  aperture.  The  thecal  inclination  is  about  30°  in  full 
profile  view,  less  in  obliquely  preserved  specimens.  Profile  stipe  width  is  O8-b0mm  in  proximal  parts, 
0 9 12  mm  in  more  distal  parts;  lateral  stipe  width  (dorsoventral  view)  is  about  05-0-6  mm.  There  are  10-5-12 
thecae  in  10  mm,  and  the  thecal  overlap  is  about  50%.  Bithecae  are  not  present  along  the  stipes.  The  observed 


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length  of  first-order  stipes  falls  within  the  range  of  variation  seen  in  H.  copiosus',  the  branching  is  dichotomous. 
The  first-order  stipes  diverge  at  ?150-180°.  A stipe  fragment  from  Grundvik,  Slemmestad  (Text-fig.  8 j ) shows 
four  orders  of  stipes,  the  most  proximal  stipe  seen  being  of  second  or  higher  order,  judging  from  the  angles 
of  dichotomy.  Cortical  thickening  of  stipes  is  variable,  but  mostly  not  readily  observed. 

Remarks.  The  species  differs  from  H.  copiosus , and  the  species  described  by  Wang  ( 1981 ),  primarily 
in  having  broader  and  somewhat  more  rigid  stipes.  The  more  rigid  appearance  might  be  explained 
in  part  by  longer  thecae  and  higher  thecal  overlap  and  in  part  by  slight  cortical  thickening.  In 
contrast  to  H.  copiosus , no  immature  specimens  of  H.  tjernviki  have  been  observed. 


Hunnegraptus  robustus  gen.  et  sp.  nov. 

Text-fig.  9 

? 1987  Dichograptid  sp.  3 Maletz,  p.  138,  pi.  5,  fig.  4. 

Name.  Denoting  the  robust  character  of  the  species,  as  compared  to  H.  copiosus  and  H.  tjernviki. 

Material.  Six  specimens,  all  illustrated  in  Text-figure  9.  Holotype  LO  5981T,  from  2 60  m at  Storeklev,  Mt 
Hunneberg.  Paratypes  PUVgl26,  LO  5982t,  LO  5983t,  from  the  graptolite-rich  band  215-2-32  m at 
Storeklev;  LO  5985t,  Storeklev,  2-60  m;  LO  5984t  from  Grundvik. 

Associated  species.  H.  copiosus. 

Stratigraphic  range.  H.  copiosus  Zone. 

Diagnosis.  Didymograptid  proximal  part  and  up  to  four  or  more  orders  of  stipes.  First-order  stipes 
consist  of  several  thecae.  Profile  stipe  width  1 -8  2-5  mm;  lateral  stipe  width  1 0-2-5  mm,  depending 
on  cortical  cover.  Dichotomous  and  irregular  lateral  branching.  Lateral  stipes  usually  narrower 
than  the  rest  of  the  rhabdosome. 

Description.  The  sicula  and  proximal  development  are  unknown,  since  only  distal  parts  are  seen  in  profile  view. 
The  observed  combined  length  of  first-order  stipes  is  24-33  mm;  the  observed  range  of  second-order  stipes  is 
from  24  to  more  than  50  mm.  The  thecae  are  long  straight  tubes,  their  length  c.  3 mm,  width  0-4  mm,  and 
overlap  about  75%.  There  are  about  12  thecae  in  10  mm.  The  profile  stipe  width  is  1-8-2-5  mm  (Text-fig.  9c). 
The  lateral  stipe  width  varies  considerably,  depending  on  the  amount  of  secondary  cortex  cover:  normally 
1 -5—2-5  mm,  but  in  some  cases  as  thin  as  10  mm.  Secondary  cortical  cover  is  less  marked  in  a distal  direction, 
but  this  is  in  no  way  regular  (see  Text-fig.  9a).  Thin  (0-7-L0  mm  wide)  lateral  stipes  occur  irregularly  in  five 
of  the  six  specimens  (see  Text-fig.  9a-b,  d f).  These  stipes  are  connected  to  the  rest  of  the  rhabdosome  by  the 
cortical  thickening,  and  thus  cannot  represent  superimposed  fragments  of  other  specimens.  As  discussed  for 
the  genus,  I consider  these  stipes  to  have  been  formed  secondarily  and  thus  ignore  them  when  counting  the  stipe 
order:  the  maximum  found  is  four  stipe  orders,  in  the  holotype.  Text-figure  9e  shows  a specimen  and  its 
counterpart,  with  three  broken  lateral  stipes  seen  on  the  counterpart  only  (after  some  preparation),  indicating 
that  they  did  not  grow  in  the  plane  represented  by  the  four  main  stipes.  The  lateral  stipes  shown  in  Text-figure 
9f  seem  to  have  been  originally  directed  slightly  upwards,  and  later  bent  down  to  the  bedding  plane  by 
compaction. 

Remarks.  The  species  differs  from  the  other  two  described  Hunnegraptus  species,  and  the  species  of 
Wang  (1981),  in  its  longer  thecae,  more  robust  stipes  and  thick  cortex  cover,  as  well  as  the 
occasional  lateral  stipes.  No  immature  specimens  have  been  identified.  The  lateral  stipes  appear  to 
have  been  formed  later  than  the  surrounding  parts  of  the  rhabdosome  (see  the  remarks  on  the 
genus). 


Genus  clonograptus  Nicholson,  1873 


Type  species.  Graptolithus  rigidus  J.  Hall,  1858. 


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text-fig.  9.  Hunnegraptus  robustus  sp.  nov.  a,  holotype,  LO  598 IT,  Storeklev  2-60  m,  showing  numerous  thin 
lateral  stipes,  possibly  a sign  of  regeneration;  the  drawing  is  a combination  of  counterparts,  b,  LO  5982t, 
Storeklev  2-32  m,  arrows  point  to  lateral  stipes;  note  the  two  closely  arranged  stipes  on  the  first-order  stipe, 
connected  proximally  by  cortical  tissue,  c,  LO  5983t,  Storeklev  2- 15-2-32  m,  a stipe  fragment  showing  thecae 
in  profile  view,  d,  PU  Vg  126,  Storeklev  227-230  cm,  the  specimen  commented  on  by  Tjernvik  (1956, 


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Diagnosis  (from  Lindholm  and  Maletz  1989).  Dichograptid  with  bilateral  rhabdosome  produced  by 
dichotomous  division  occurring  at  irregular  intervals;  second  dichotomy  in  most  species 
consecutive,  forming  a tetragraptid  proximal  part,  but  can  be  delayed  for  a couple  of  thecae; 
branches  diverging  proximally,  while  distally  diverging,  subparallel,  or  flexuous;  thecal  shape 
variable,  unknown  in  many  species  assigned  to  the  genus;  central  disc  unknown,  secondary 
development  of  cortical  overgrowth  in  many  species,  particularly  in  proximal  parts. 

Remarks.  The  genus  Clonograptus  was  treated  by  Lindholm  and  Maletz  (1989).  It  was  reinterpreted 
as  a form  genus  ( Clonograptus  sensu  lato ) consisting  of  the  phylogenetically  based  subgenus 
Clonograptus  ( Clonograptus ) (=  Clonograptus  sensu  stricto ) and  additionally  a number  of  species 
not  known  in  enough  detail  for  inclusion  in  any  phylogenetically  based  group.  In  the  same  paper 
Clonograptus  was  transferred  to  the  Dichograptidae,  since  there  are  no  bithecae  along  the  stipes  in 
the  type  species. 


Clonograptus  cf.  norvegicus  Monsen,  1937 
Text-fig.  10f 

cf.  1937  Clonograptus  norvegicus  Monsen,  pp.  198-200,  pi.  20;  non  pi.  5,  fig.  22. 

cf.  1987  Clonograptus  norvegicus  Monsen;  Maletz,  p.  58,  fig.  41:1,  2. 

Material.  One  incomplete,  nearly  flattened,  specimen  with  proximal  part,  associated  with  scattered  stipe 
fragments  of  the  species,  found  on  PMO  73 . 200  and  73 . 204  (counterparts),  in  grey  shale  from  0-5  m above  the 
Ceratopyge  Limestone  at  Bodalen,  Slemmestad. 

Associated  species.  None. 

Stratigraphic  range.  H.  copiosus  Zone,  possibly  also  T.  phyllograptoides  Zone. 

Diagnosis  (of  C.  norvegicus , based  on  Monsen  1937).  A clonograptid,  irregularly  branching  to  at 
least  13  orders  of  stipes.  Second-  to  fourth-order  stipes  progressively  longer,  but  within  3-8  mm  in 
length;  higher  orders  on  average  10  mm  long  or  more.  A marked  cortex  cover  (peridermal  film?) 
gives  a lateral  width  of  3 mm  proximally  and  down  to  less  than  2 mm  distally.  The  cortex  obscures 
all  thecal  details.  Possibly  8-9  thecae  in  10  mm. 

Description.  In  my  specimen,  no  details  of  proximal  development  or  thecae  are  visible  due  to  the  cortex  cover 
and  the  horizontal  orientation  of  the  rhabdosome.  The  position  of  the  sicula  can  be  seen,  and  the  outline  of 
the  stipes  and  branching  points  within  the  cortex  film  can  be  partly  discerned,  indicating  that  the  primary  stipes 
are  of  unequal  length.  There  is  probably  one  theca  in  one  first-order  stipe  and  2-3  in  the  other.  The  thecal 
spacing  is  unknown,  however,  and  if  it  is  much  less  than  10  in  10  mm  it  could  indicate  that  the  specimen  is 
triradiate  rather  than  biradiate.  The  lateral  width  of  the  stipes  excluding  the  cortex  cover  is  03-06  mm,  the 
total  lateral  width  varies  from  15  to  2 0 mm  in  the  proximal  part  down  to  less  than  1 mm  in  distal  parts.  The 
branching  pattern  seems  to  be  somewhat  irregular,  but  in  general  the  distances  between  branchings  increase 
in  a distal  direction.  Seven  orders  of  stipes  are  seen,  and  the  length  of  second-  to  fifth-order  stipes  are  (assuming 
two  primary  stipes)  2-6  mm,  3-7  mm,  4-9  mm,  and  6-10  mm.  The  specimen  may  not  have  been  fully  planar; 
it  appears  that  at  least  one  stipe  crosses  the  others  at  a lower  level  in  the  slab.  The  branching  angles  are  variable, 
c.  60-120°  in  proximal  branchings  and  45-70°  in  the  more  distal  parts.  Higher-order  stipes  sometimes  curve 
to  adopt  a more  parallel  orientation. 


pp.  1 17-1 18);  a broken  lateral  stipe  (arrow)  is  seen  on  the  lower  left  stipe,  e,  LO  5984t,  Grundvik,  Slemmestad, 
piece  and  mirror  image  of  counterpart  shown  to  illustrate  lateral  stipes  at  an  angle  to  the  plane  formed  by  the 
main  stipes;  the  lateral  stipes  on  the  upper  left  are  connected  to  the  main  stipe  by  thick  cortex  proximally.  f, 
LO  5985t,  Storeklev  2-60  m,  a stipe  fragment  with  paired  lateral  stipes.  Stippling  indicates  flexure  - the  lateral 

stipes  were  originally  directed  upwards. 


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text-fig.  10.  a,  c,  d,  Clonograptus  magnus  sp.  nov;  a,  holotype  PMO  108.564-108.565,  Slemmestad;  the 
drawing  is  a combination  of  counterparts;  c,  d.  PMO  108.561-108.562,  same  locality  as  a;  d is  an 
enlargement  of  the  obliquely  positioned  fragment  in  c,  showing  the  thecae  in  profile  view;  c is  combined  from 
piece  and  counterpart,  b,  Clonograptus  sp.  1,  PMO  97.708,  Slemmestad;  drawing  from  latex  cast.  E, 
Clonograptus  sp.  2,  LO  5986t,  Krapperup  core  1 42-46— 1 42-56  m.  F,  Clonograptus  cf.  norvegicus , PMO  73-200, 
73-204;  the  drawing  is  a combination  of  counterparts. 


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307 


Remarks.  The  fragmentary  nature  and  lack  of  information  on  proximal  development  and  thecal 
shape  of  the  specimen  makes  identification  very  difficult.  C.  norvegicus  is  a rare  species  and  the 
original  description  by  Monsen  (1937)  was  based  on  only  one  specimen  with  most  details  obscured 
by  the  cortex  cover.  That  specimen  has  at  least  13  orders  of  stipes  and  is  more  robust  than  the 
present  specimen,  which  is  unlikely  to  have  been  of  that  size.  The  robustness  may  be  caused  entirely 
by  a thicker  cortex  cover,  associated  with  its  greater  size.  Monsen’s  specimen  was  said  to  be 
associated  with  ‘ Didymograptus  minutus  var.  pygmaeus \ hence  Monsen  assigned  it  to  the  middle 
part  of  the  Arenig.  However,  small  pendent  specimens  very  much  resembling  D.  minutus  occur  also 
at  a level  slightly  below  the  base  of  the  T.  phyllograptoides  Zone  (see  Text-fig.  14c,  F).  Monsen’s 
specimen  comes  from  Grundvik,  Slemmestad,  one  of  the  localities  where  the  beds  below  the  T. 
phyllograptoides  Zone  are  easily  accessible.  Erdtmann  (19656,  p.496)  reported  having  found 
fragments  of  the  species  at  a very  low  level  in  the  Toyen  section.  However,  his  specimens  have  since 
been  lost  and  the  statement  cannot  be  verified. 

Maletz  (1987)  reported  the  species  from  Mt  Hunneberg,  from  the  localities  Tunhem  and 
Storeklev.  At  the  latter  locality  it  was  found  at  the  same  level  as  the  richest  finds  of  the  H.  copiosus 
fauna.  Large-sized  stipe  fragments  with  thick  cortex  cover  are  present  also  in  the  T.  phyllograptoides 
Zone  at  Mt  Hunneberg  (one  specimen  from  Mossebo,  SGU  collections)  as  well  as  at  Galgeberg, 
Oslo  (Bergen  Museum,  Monsen  collection  231). 

The  only  other  Clonograptus  s.l.  species  of  a similar  outline  is  C.  trochograptoides  Harris  and 
Thomas,  1939.  The  pattern  of  branching  and  cortex  cover  is  identical,  but  stipes  of  a given  order 
are  somewhat  shorter,  giving  a more  compact  rhabdosome.  C.  trochograptoides  was  said  to  have 
thecae  of  Clonograptus  s.s.  type,  8-9  in  10  mm. 

Subgenus  clonograptus  (clonograptus)  Nicholson,  1873 

Diagnosis.  As  for  genus,  but  with  thecae  straight  or  slightly  curved  simple  tubes,  overlapping  one- 
third  to  two-thirds  of  their  length;  proximal  development  isograptid,  dextral. 

Remarks.  A number  of  genera  were  synonymized  with  Clonograptus  ( Clonograptus ) by  Lindholm 
and  Maletz  (1989),  most  importantly  Temnograptus  Nicholson,  1876. 


Clonograptus  ( Clonograptus ) magnus  sp.  nov. 

Text-fig.  10  a,  c,  d 

Name.  Latin  magnus , big. 

Material.  One  specimen  with  proximal  part  preserved  (holotype  PMO  108.564-108.565;  Text-fig.  10a)  and 
one  distal  stipe  fragment  (paratype  PMO  108.561-108.562)  from  0- 5-1-2  m above  the  Ceratopyge  Limestone 
at  Slemmestad  crossroads.  Additionally  there  are  four  stipe  fragments  from  3-42-3-60  m ( + a gap  of  unknown 
extent,  probably  0-5-2  m)  above  the  Ceratopyge  Limestone  at  Grundvik,  Slemmestad. 

Associated  species.  H.  copiosus , reclined  Tetragraptus  indet.  (juvenile). 

Stratigraphic  range.  H.  copiosus  Zone,  possibly  also  T.  phyllograptoides  Zone. 

Diagnosis.  A very  robust  Clonograptus  s.s.  with  a considerable  cortical  thickening  in  mature 
specimens.  Tetragraptid  proximal  part,  second-order  stipe  length  approximately  10-40  mm,  third 
and  higher  order  generally  over  40  mm.  There  are  at  least  five  stipe  orders.  9—10  thecae  in  10  mm, 
thecal  overlap  two-thirds  or  more,  profile  stipe  width  1 -5—2  0 mm. 

Description.  Details  of  the  proximal  development  are  unknown.  In  the  only  specimen  with  proximal  part 
(Text-fig.  10  a),  first-order  stipes  consist  of  one  theca  each  and  second-order  stipes  are  from  10  to  38  mm  long. 
The  specimen  does  not  show  complete  third-order  stipes,  but  the  five  longest  fragments  are  38-54  mm  long. 


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The  angle  between  the  second-order  stipes  is  rather  high,  c.  105°,  whereas  the  angle  between  the  third-order 
stipes  is  low,  c,  45-70°.  There  are  9-10  thecae  in  10  mm.  A third-order  stipe  is  preserved  in  partial  profile  view, 
giving  an  estimate  of  profile  stipe  width  of  I -5  to  2-0  mm.  As  far  as  can  be  seen  the  thecae  are  rather  long  and 
narrow.  All  of  this  specimen  is  covered  by  cortex,  giving  a lateral  stipe  width  of  approximately  4 mm  for  the 
first-order  stipes,  2-5— 2-8  mm  for  second-order  stipes,  and  1 -5-2-3  mm  for  third-order  stipes. 

The  largest  stipe  fragment  (Text-fig.  10c,  d)  has  less  cortical  cover  than  the  previous  specimen.  The  fragment 
has  four  orders  of  stipes,  the  most  proximal  one  probably  of  third  or  higher  order.  The  length  of  the  two  middle 
orders  of  stipes  is  47  and  77  mm.  There  are  9-5  thecae  in  10  mm.  The  thecae  are  slightly  curved,  with  about 
two-thirds  to  three-quarters  of  overlap.  The  thecal  apertures  are  concave.  The  profile  stipe  width  is  18  mm  and 
the  lateral  stipe  width  is  1-3-1  -5  mm.  There  are  no  bithecae. 

The  remaining  stipe  fragments  contain  only  one  dichotomy  each.  They  all  have  9-10  thecae  in  10  mm,  and 
a profile  stipe  width  of  1 -5—2-0  mm. 

Remarks.  The  only  Clonograptus  species  of  a comparable  size  are  C.  multiplex  (Nicholson,  1868) 
and  C.  magnificus  (Pritchard,  1892).  Neither  of  these  have  the  massive  cortical  thickening 
characteristic  of  this  species.  Also,  its  branching  angles  differ  from  those  of  these  two  species. 

A stipe  fragment  from  Taimyr,  identified  by  Obut  and  Sobolevskaya  (1962)  as  Temnograptus  aflf. 
noveboracensis  Ruedemann,  may  be  conspecific  with  C.  magnus. 


Form  genus  tetragraptus  Salter,  1863  (=  tetragraptus  s.I.) 

Tetragraptus  longus  sp.  nov. 

Text-figs  1 1 a-d  and  12 

Name.  Latin  longus , long,  referring  to  the  length  of  the  stipes. 

Material.  121  specimens  in  all,  most  of  them  more  or  less  broken.  Nearly  all  of  them  are  from  Galgeberg,  east- 
central  Oslo  (found  on  PMO  58.969,  58.970);  14  specimens  come  from  Slemmestad  (PMO  97.702,  97.708 
and  one  specimen,  LR  1,  in  the  Lund  collections),  and  one  from  the  Krapperup  core  ( 1 29-46—1 29-54  m).  The 
holotype  is  found  on  PMO  58.970  (text-fig.  1 1A),  the  paratypes  on  PMO  58.969  and  97.708. 

Associated  species.  H.  copiosus , H.  tjernviki,  T.  cf.  krapperupensis. 

Stratigraphic  range.  H.  copiosus  Zone. 

Diagnosis.  A thin-stiped  (0-7  1 I mm)  horizontal  tetragraptid,  with  small  central  disc  in  mature 
specimens.  The  divergence  angle  between  second-order  stipes  is  90°  or  less.  There  are  9-5-1 1 thecae 
in  10  mm.  The  stipes  may  become  extremely  long. 

Description.  The  species  has  a normal  tetragraptid  proximal  part  (Text-fig.  1 1 c),  i.e.  the  first-order  stipes  are 
composed  of  one  theca  each.  All  specimens  are  preserved  horizontally,  and  thus  do  not  reveal  any  details  of 
proximal  development  or  the  possible  presence  of  a sicular  bitheca.  Many  stipes  are  preserved  in  relief  and 
show  total  absence  of  bithecae.  The  stipes  are  0-7-0-9  mm  wide  in  profile  view,  up  to  1 1 mm  in  very  large 
specimens.  The  lateral  width  is  about  0-4— 0-5  mm,  but  the  stipes  very  often  show  the  profile  view.  The  longest 
stipe  fragments  encountered  were  710  and  680  mm  respectively  (Text-fig.  12;  all  specimens  on  the  slab  are 
fragmented  - cf.  Text-fig.  10b  - but  there  appears  to  be  no  tectonic  distortion).  They  probably  both  belong  to 
one  specimen.  The  thecae  are  straight  tubes,  about  three  times  as  long  as  wide  and  with  straight  apertures. 
There  are  9-5-1 1 thecae  in  10  mm  and  they  overlap  for  one  half  of  their  length  or  slightly  less.  The  thecal 
inclination  is  about  20°.  Mature  specimens  develop  a small  central  disc  (Text-fig.  1 1 a,  b).  The  largest  one  seen 
is  approximately  2 by  4 mm.  No  more  than  2-3  thecae  per  second-order  stipe  are  encroached  upon  by  the  disc. 
Cortical  thickening  has  not  been  noticed  along  the  second-order  stipes,  but  is  likely  to  be  present  to  some 
degree,  considering  the  relative  straightness  of  most  stipes  seen  in  Text-figure  12.  The  second-order  stipes 
normally  make  an  angle  of  80-90°,  slightly  more  in  a few  specimens.  The  long  stipe  fragments  in  Text-figure 
12  seem  to  have  been  curved  by  rotational  movement  during  post-mortem  descent  to  the  sediment  surface. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


309 


text-fig.  1 1.  a-d,  Tetragraptus  longus  sp.  nov.,  Galgeberg,  east-central  Oslo,  a,  holotype,  PMO  58.970,  with 
a well-developed  central  disc;  judging  from  the  size  of  the  disc,  the  stipes  must  have  been  very  long,  b-d, 
PMO  58.969;  b,  a specimen  with  the  beginnings  of  a disc;  c,  specimen  partly  preserved  in  relief  in  the  proximal 
part,  showing  a normal  tetragraptid  branching  pattern;  d,  typical  specimen,  without  central  disc,  e-h,  Gen. 
et  sp.  mdet.  1,  all  from  Slemmestad.  E,  PMO  108.599,  a complete  immature  specimen.  F,  PMO  108.566,  a 
specimen  showing  the  proximal  branching  pattern  inside  the  central  disc.  G,  PMO  108.567,  a specimen  with 
thecae  in  profile  view  and  an  immature  central  disc,  h,  PMO  108 . 599,  proximal  fragment  of  a presumably  large 

specimen  with  a well-developed  central  disc. 


Remarks.  Thin  horizontal  tetragraptids  are  most  commonly  lumped  together  under  the  name  T. 
quadribrachiatus . As  was  shown  by  Williams  and  Stevens  (1988),  even  the  type  collection  of  J.  Hall 
contains  specimens  of  two  unrelated  taxa  of  different  age.  Their  recommendation  was  that  the  name 
should  not  be  used  until  the  taxon  was  redefined.  T.  longus  differs  from  the  original  description  of 
T.  quadribrachiatus  in  having  a central  disc  in  mature  specimens.  J.  Hall  (1865)  noted  that  he  had 
never  seen  one  in  T.  quadribrachiatus.  Also,  the  stipe  divergence  angles  of  T.  longus  are  somewhat 
unusual,  being  more  often  below  than  above  90°.  The  great  length  of  the  stipes  is  also  unique. 

The  number  of  specimens  found  might  suggest  that  the  species  is  a common  one.  This  is  not  the 
case -it  appears  to  be  an  invasion  species,  found  covering  surfaces  in  almost  monotypic 
assemblages,  and  being  very  rare  in  intervening  beds. 


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text-fig.  12.  Tetragraptus  longus  sp.  nov.,  PMO  97.708,  Slemmestad.  Illustration  of  part  of  a very  big  slab, 
showing  ten  (of  a total  of  twelve)  specimens  with  proximal  part,  and  two  pairs  of  very  long  stipes  of  the  species, 
possibly  both  belonging  to  one  specimen.  The  arrows  point  in  the  distal  direction,  and  are  placed  along  the 
ventral  side  of  the  stipe.  Associated  fauna  is  not  shown. 


Tetragraptus  krapperupensis  sp.  nov. 

Text-fig.  13a,  c,  e;  cf.  Text-fig.  1 3 f 

Name.  From  the  Krapperup  core. 

Material.  6 specimens,  all  from  the  Krapperup  core,  three  of  them  at  140  87  m,  the  other  three  at  140-30  m. 
Holotype  LO  5988T  (140-87  m;  Text-fig.  13  c),  paratypes  LO  5987t  and  LO  5989t  (both  from  140-30  m).  One 
specimen  of  T.  cf.  krapperupensis  (LO  5990t)  is  present  at  1 29-46—1 29-54  m. 


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311 


Associated  species.  A.  murrayi , Didymograptus  sp.  1. 

Stratigraphic  range.  A.  murrayi  Zone,  possibly  also  H.  copiosus  Zone. 

Diagnosis.  A three-stiped  species  of  slightly  declined  habit.  Sicular  length  2-2— 2-5  mm,  stipe  width 
1-3  mm  proxinially  and  up  to  21  mm  distally,  9-5-11  thecae  in  10  mm,  thecal  overlap  about  one 
half,  distal  thecal  inclination  35^45°. 

Description.  The  sicula  is  2-2-2- 5 mm  long  and  about  O4-0-7  mm  wide  at  the  aperture.  No  specimen  shows  any 
details  of  proximal  development.  Only  stipe1  has  a second  dichotomy,  after  the  first  theca,  resulting  in  3 final 
stipes.  The  thecae  are  straight  or  slightly  curved,  about  2-3  times  as  long  as  wide.  They  are  inclined  at  about 
35^45°  to  the  dorsal  margin  of  the  stipes.  Well-preserved  thecae  are  somewhat  denticulate  and  have  a concave 
aperture.  The  aperture  is  generally  inclined  at  60-70°  to  the  dorsal  margin  of  the  stipes.  The  thecal  overlap  is 
mostly  difficult  to  see,  but  appears  to  be  approximately  one  half.  There  are  9-5-1 1 thecae  in  10  mm,  the  lower 
value  being  found  in  the  largest  specimen.  The  proximal  stipe  width  is  about  1 -3—1  -4  mm,  the  maximum  stipe 
width  varies  with  the  length  of  the  stipes,  from  T5  mm  in  small  specimens  to  2-1  mm  in  the  largest  one.  Across 
a specified  theca  the  stipes  are  somewhat  wider  in  larger  specimens,  possibly  suggesting  a certain  amount  of 
continued  thecal  growth.  Two  specimens  (see  Text-fig.  13  a)  indicate  a plaited  thecal  structure  - or  triad 
budding : due  to  the  relatively  low  relief,  the  presence  or  absence  of  bithecae  along  the  stipes  cannot  be  verified. 
The  species  could  belong  to  the  transitional  forms  with  only  traces  remaining  of  an  anisograptid  structure 
(Lindholm  and  Maletz  1989).  The  stipes  are  declined  in  their  proximal  part.  They  are  straight  throughout  or 
have  a slight  dorsally  concave  curvature.  In  life,  the  stipes  were  probably  slightly  declined. 

One  specimen,  found  a few  metres  higher  in  the  core,  has  somewhat  narrower  stipes  and  more  closely  set 
thecae  (Text-fig.  1 3 f).  Until  more  material  of  the  species  is  known,  I refer  to  it  as  T.  cf.  krapperupensis. 

Remarks.  No  four-stiped  rhabdosomes  have  been  observed  in  the  beds  containing  T.  krapperupensis 
and  the  assignment  of  the  species  to  the  dichograptid  form  genus  Tetragraptus  is  based  on  the  fact 
that  no  bithecae  have  been  identified,  and  that  there  are  only  two  orders  of  dichotomy;  there 
appears  to  be  no  other  existing  dichograptid  genus  for  three-stiped  forms.  However,  since 
preservation  precludes  observation  of  bithecae,  these  could  in  fact  be  present,  in  which  case  the 
species  would  have  to  be  referred  to  an  anisograptid  genus.  Triograptus  is  the  only  three-stiped 
anisograptid  genus.  It  has  three  ‘primary’  stipes,  i.e.  the  second-order  dichotomy  follows  the  first 
without  intervening  unicalycal  theca  (Cooper  and  Fortey  1983),  although  one  specimen  (Text-fig. 
1 3 h)  in  the  collection  forming  the  basis  of  Monsen’s  (1925)  original  description  of  the  type  species, 
Triograptus  osloensis , appears  to  have  two  primary  stipes,  one  of  them  branching  after  theca  1,  just 
like  the  species  here  described.  However,  the  thecal  morphology  of  Triograptus  osloensis  (Text-fig. 
1 3 g)  makes  it  very  unlikely  that  the  two  species  are  closely  related.  Near  the  base  of  the  Krapperup 
core  there  is  one  specimen  probably  belonging  to  another  Triograptus  species  (Text-fig.  1 3 1).  Also 
this  species  has  a thecal  shape  quite  unlike  that  of  T.  krapperupensis. 

Three-stiped  rhabdosomes  of  roughly  the  same  shape  are  found  also  in  younger  beds  in  southern 
Scandinavia.  Five  specimens  were  found  with  the  H.  copiosus  fauna  in  Slemmestad  (PMO  108.566, 
108 . 569-108 . 570,  108 . 598;  Text-fig.  13  d).  The  thecal  morphology  agrees  reasonably  well  with  that 
of  T.  krapperupensis , but  the  sicula  is  much  stouter  and  longer.  This  form  is  found  together  with 
four-stiped  specimens.  Three-stiped  forms  are  especially  common  in  the  overlying  T.  phyllo- 
graptoides  Zone  (more  than  150  specimens  from  Mt  Hunneberg  in  RM,  SGU,  and  Lund  collections 
have  been  investigated),  where  three  typical  shapes  can  be  seen  among  the  declined  to  slightly 
reclined  forms.  Some  additional  specimens  are  preserved  horizontally,  so  that  thecal  characteristics 
are  obscured.  This  fauna  has  not  yet  been  studied  in  enough  detail  to  see  if  there  is  a continuous 
range  of  variation  among  its  members  or  not,  but  it  seems  possible  that  there  are  distinct  forms, 
some  or  all  of  which  may  be  related  to  four-stiped  forms,  i.e.  merit  the  name  Tetragraptus.  One  form 
(Text-fig.  13b,  j)  is  very  similar  in  outline  to  T.  krapperupensis.  I hesitate  to  synonymize  them  since 
there  are  indications  of  a plaited  thecal  structure  in  T.  krapperupensis , whereas  specimens  of  the 
younger  fauna  have  normal  dichograptid  stipes.  Perhaps  they  formed  part  of  a three-stiped  lineage 
with  separate  bithecal  reduction.  Where  three-  and  four-stiped  specimens  occur  in  the  same  beds  it 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  13.  Tetragraptus  krapperupensis  sp.  nov.  and  comparative  material,  a,  c,  e,  T.  krapperupensis  sp.  nov., 
all  from  the  Krapperup  core;  a,  LO  5987t,  140-30  m,  the  left-hand  stipe  shows  plaited  thecal  structure;  c, 
holotype,  LO  5988T,  140-87  m,  the  largest  specimen;  the  drawing  is  a combination  of  counterparts;  e,  LO 
5989t.  140-30  m,  a smaller  specimen  with  narrower  maximal  width,  b,  j,  Tetragraptus  sp.  1,  Mossebo,  Mt 


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313 


is  often  difficult  to  see  if  they  are  conspecific  since  the  proximal  parts  of  the  four-stiped  specimens 
tend  to  be  preserved  horizontally  (dorsoventral  view),  so  that  the  sicula  and  proximal  width  of  stipes 
etc.  cannot  be  seen. 

Three-stiped  rhabdosomes  of  various  species  appear  to  be  present  through  most  of  the  Arenig 
of  southern  Scandinavia.  In  the  T.  phyllograptoides  Zone,  in  addition  to  the  forms  discussed  above, 
there  is  a pendent  three-stiped  form  which  has  no  associated  four-stiped  pendent  specimens. 
According  to  S.  H.  Williams  (pers.  comm.)  it  is  identical  to  P.  cf.  pendens  from  Newfoundland 
(Williams  and  Stevens  1988).  The  Newfoundland  fauna,  however,  contains  both  three-  and  four- 
stiped  specimens.  In  beds  above  the  T.  phyllograptoides  Zone  in  Scandinavia,  practically  all  three- 
stiped  forms  have  reclined  rhabdosomes. 

Some  three-stiped  forms  from  the  T.  phyllograptoides  Zone  at  Mt  Hunneberg  were  described  by 
Maletz  (1987)  under  the  name  of  T.  triograptoides  (nomen  nudum;  junior  homonym  of  T. 
triograptoides  Harris  and  Thomas,  1938),  but  had  been  observed  already  by  Tornquist  (1904,  pi.  1, 
fig.  20),  who  grouped  them  with  four-stiped  forms  as  T.  serra  ( = T.  amii  according  to  current 
usage). 

Non-triograptid,  more  or  less  horizontal,  three-stiped  forms  of  Tremadoc-Arenig  age  are  known 
also  from  other  areas.  Tetragraptus  otagoensis  and  T.  decipiens  (three-stiped  form)  from  New 
Zealand  were  shown  by  Bulnran  and  Cooper  (1969)  to  have  the  same  branching  pattern  as  the 
Scandinavian  forms.  T.  otagoensis  is  of  La  2 zone  age,  and  is  therefore  roughly  coeval  with  T. 
krapperupensis , but  has  considerably  narrower  stipes  than  the  latter.  The  three-stiped  form  of  T. 
decipiens  is  somewhat  younger.  La  3 zone,  approximately  coeval  with  the  T.  phyllograptoides  Zone 
fauna  of  Mt  Hunneberg.  It  appears  to  have  stipes  narrower  than  the  mature  Scandinavian 
specimens,  but  it  is  worth  noting  that  immature  Scandinavian  specimens,  with  stipes  of  comparable 
length  to  that  of  the  New  Zealand  specimens,  also  have  a comparable  stipe  width.  As  in  the 
Scandinavian  specimens,  the  second-order  dichotomy  in  the  New  Zealand  specimens  is  based  on 
stipe1  (the  stipe  developed  on  the  th  l1  side),  quoted  erroneously  (R.  A.  Cooper  pers.  comm.)  by 
Bulman  and  Cooper  (1969)  and  Cooper  (1979)  as  the  stipe2  side.  The  three-stiped  form  of  T. 
decipiens  has  not  yet  been  reported  from  Australia  (R.  A.  Cooper  pers.  comm.). 

Harris  and  Thomas  (1938)  described  Tetragraptus  triograptoides  from  the  lowermost  part  of  the 
Bendigonian  of  Victoria.  This  is  a very  slender  form,  belonging  to  the  sigmagraptines,  judging  by  its 
thecal  characters.  Chen  el  al.  (1983)  reported  a specimen  of  a three-stiped  extensiform  species, 
Adelograptus  rohustus , from  Jiangxi,  South  China,  associated  with  T.  approximate . Its  dimensions, 
apart  from  the  comparatively  broad  proximal  part  of  the  stipes,  are  not  far  from  those  of  certain 
specimens  found  at  Mt  Hunneberg,  but  it  has  bithecae  along  the  stipes.  A probably  middle  Arenig 
form  was  described  from  Czechoslovakia  (T.  postlethwaitii\  Kraft  1987).  It  resembles  the  form 
illustrated  in  Text-figure  13b  except  in  having  slightly  narrower  stipes.  The  species  contains  both 
three-  and  four-stiped  forms. 


Form  genus  didymograptus  M‘Coy,  1851  (=  didymograptus  sd.) 
Didymograptus  sp.  1 
Text-fig.  14a,  b 

v cf.  1986  Corymbograptus  sp.  1 Gutierrez  Marco,  pp.  445-447,  text-fig.  39d-m;  pi.  14,  figs  2,  4,  5. 

v cf.  1988  Didymograptus  cf.  sinensis  Lee  and  Chen;  Molyneux  and  Rushton,  p.  66,  fig.  9a,  b. 


Hunneberg;  b,  SGU  Type  8020;  J,  RM  Cn  1838,  the  biggest  specimen  found,  d,  Tetragraptus  sp.  2,  PMO 
108.569-108.570,  Slemmestad;  the  drawing  is  a combination  of  counterparts,  f,  T.  cf.  krapperupensis , LO 
5990t,  Krapperup  core  1 29-46—129-54  m.  g-h,  Triograptus  osloensis  Monsen,  both  on  PMO  59.215, 
Stensberggaten,  central  Oslo,  Ceratopyge  Shale,  155-180  cm  below  the  Ceratopyge  Limestone;  G,  part  of  a 
stipe  fragment  showing  shape  of  thecae;  h,  an  aberrant  specimen  with  two  primary  stipes  and  a second-order 
dichotomy,  i,  Triograptusl  sp.  1,  LO  60 1 5t,  Krapperup  core,  1 51-45-151 -46  m. 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  14.  a,  b,  Didymogrciptus  sp.  1,  Krapperup  core  137-72-1 37-76  m,  two  associated  specimens;  a,  LO 
599 It,  the  largest  specimen  found,  slightly  deflexed;  B,  LO  5992t,  a seemingly  declined  specimen,  c,  f, 
Didymogrciptus  sp.  2,  Krapperup  core,  1 18-50-1 18-54  m,  two  associated  specimens;  c,  LO  5993t;  f,  LO  5994t. 
d,  E,  G,  H,  Tetragraptus  phyllograptoides  from  near  the  base  of  the  range  of  the  species;  all  have  considerably 
narrower  stipes  than  the  typical  form;  from  two  localities  in  the  Slemmestad  area;  d,  LO  5995t,  immature 
Phyllograptus-hke  specimen,  a-b  pair;  dotted  circle  indicates  the  broken  connection  towards  the  sicula;  e,  LO 
5996t,  a probably  three-stiped  specimen ; the  drawing  is  a combination  of  counterparts ; G,  LO  5997t,  the  largest 
specimen  found,  a-b  pair;  as  in  d,  the  connection  towards  the  sicula  is  broken;  h,  LO  5998t,  a probably  three- 
stiped  specimen  showing  few  thecae  in  the  conjoined  part  of  the  stipes,  i,  Tetragraptus  sp.  3,  PMO  1 12.967, 
112.969,  Slemmestad,  associated  with  a Hunnegraptus  fauna;  a specimen  in  medium  relief  with  the  proximal 
part  preserved  as  a mould;  sicular  outline  drawn  from  counterpart. 


Material.  10  specimens  from  the  interval  147-33-137-70  m of  the  Krapperup  core.  Most  specimens  are  small, 
showing  no  more  than  4 thecae  per  stipe. 

Associated  species.  A.  murrayi , T.  krapperupensis. 

Stratigraphic  range.  A.  murrayi  Zone,  and  possibly  higher  beds. 

Diagnosis.  A thin  (c.  07-0-8  mm)  deflexed  to  declined  didymograptid  with  sicular  length  about 
1-4  mm  and  around  12  thecae  in  10  mm.  Thecae  straight,  inclined  at  c.  30°. 

Description.  All  specimens  are  too  flattened  to  show  any  details  of  proximal  development  or  the  possible 
presence  of  bithecae.  The  sicula  is  straight,  1-2-1  -6  mm  long  and  about  0-3  mm  wide  at  the  aperture.  It 
protrudes  about  07-0-9  mm  above  the  dorsal  margin  of  the  rhabdosome.  The  thecae  are  almost  straight  tubes, 
inclined  at  about  30°.  Their  apertures  are  straight  or  slightly  concave,  inclined  at  70-80  ° to  the  dorsal  margin 
of  the  rhabdosome.  There  are  normally  12  thecae  in  10  mm,  but  the  total  variation  seen  is  11-14.  The  stipes 
are  0-6-0-7  mm  wide  proximally,  widening  to  about  0-8  mm  or,  rarely,  1-Omrn  distally.  The  shape  of  the 
rhabdosome  is  slightly  deflexed  or  declined,  with  a stipe  divergence  angle  of  120-145  °. 


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315 


Remarks.  The  assignment  of  this  species  to  Didymograptus  s.l.  is  based  on  the  fact  that  no  bithecae 
have  been  seen  along  the  stipes.  Considering  the  age  of  the  fauna,  however,  it  is  possible  that 
bithecae  are  present,  but  not  detectable  due  to  the  flattened  state  of  the  rhabdosomes.  If  so,  the 
species  will  have  to  be  referred  to  Kiaerograptus. 

The  general  shape  of  the  rhabdosome  of  this  species  is  common  to  several  species  throughout 
higher  parts  of  the  Arenig  and  even  the  lower  part  of  the  Llanvirn,  but  the  only  similar  species  of 
roughly  the  same  age  are  Corymbograptus  sp.  1 Gutierrez  Marco,  1986,  and  Didymograptus  cf. 
sinensis  described  by  Molyneux  and  Rushton  (1988).  Corymbograptus  sp.  1 differs  only  in  having 
a somewhat  shorter  sicula  and  narrower  proximal  width,  as  well  as  a more  accentuated  deflexed 
shape  in  some  of  the  specimens.  D.  cf.  sinensis  is,  in  my  opinion,  a synonym  of  that  species,  differing 
only  in  having  slightly  more  thecae  in  10  mm,  well  within  the  normal  limits  of  variation  of  a species 
of  that  age.  There  are  only  a couple  of  reasonably  large  Swedish  specimens,  not  necessarily 
representative  of  the  mean  of  the  population,  hence  further  finds  may  prove  the  Swedish  species  to 
be  conspecific  with  the  Spanish/English  one. 


Gen.  et  sp.  indet.  1 
Text-fig.  1 1 e-h 

Material.  4 specimens  from  Slemmestad  crossroads,  c.  0-5-1 -0  m above  the  Ceratopyge  Limestone,  found  on 
PMO  108.566,  108.567  and  108.599. 

Associated  species.  H.  copiosus , Clonograptus  s.s.  sp.  indet.,  3-stiped  extensiform  tetragraptids,  P.  tenuis , P.  cf. 
rarus. 

Stratigraphic  range.  H.  copiosus  Zone. 

Diagnosis.  A five-stiped  rhabdosome,  with  a tetragraptid  proximal  part.  Stipe  width  c.  1-6  mm, 
9-5-1 1 thecae  in  10  mm.  A central  disc  is  found  in  mature  specimens. 

Description.  All  four  specimens  are  preserved  horizontally,  obscuring  details  of  proximal  morphology.  The 
proximal  part  is  tetragraptid,  however,  with  one  theca  per  first-order  stipe.  A well-developed  central  disc  is 
found  in  the  most  mature  specimens.  The  two  largest  discs  measure  2 by  4 and  2 by  5 mm  respectively  (Text- 
fig.  1 1 f,  h).  The  only  specimen  showing  thecae  in  profile  view  (Text-fig.  1 1 G),  has  faint  beginnings  of  a disc. 
The  specimen  is  preserved  in  low  relief  and  shows  possible  plaited  thecal  structure  along  one  stipe 
(alternatively,  it  represents  a compression  structure).  A characteristic  of  the  species  is  that  one  of  the  second- 
order  stipes  divides  consecutively.  There  are  no  indications  in  the  available  material  of  any  further  dichotomies, 
and  it  may  be  presumed  that  the  final  number  of  stipes  is  five,  especially  since  there  seems  to  be  a certain 
amount  of  readjusting  of  the  stipe  angles,  to  even  out  the  distances  between  the  stipes.  However,  this  is 
unfortunately  difficult  to  prove  due  to  the  fragmentary  state  of  the  rhabdosomes.  The  thecae  are  slightly  curved 
and  somewhat  expanded  tubes,  and  slightly  denticulate.  The  thecal  overlap  is  about  60%  and  there  are  9-5-1 1 
thecae  in  10  mm.  The  profile  stipe  width  is  1-6  mm,  the  lateral  width  0- 5-0-7  mm. 

Remarks.  The  three  orders  of  stipes  present  in  these  specimens  would  suggest  the  use  of  the  genus 
name  Dichograptus.  A reduction  of  the  final  stipe  number  is  known  to  occur  within  Dichograptus. 
However,  for  the  following  reasons  I prefer  not  to  assign  these  specimens  to  that  genus.  Firstly,  the 
Slemmestad  form  is  older  than  any  reported  species  of  the  genus  and,  secondly,  I have  not  come 
across  any  definite  Dichograptus  specimens  from  the  lower  Arenig  of  Scandinavia.  Additionally 
Dichograptus  (as  well  as  Tetragraptus)  is  likely  to  be  a form  genus  and  its  type  species,  D.  sedgwicki , 
has  never  been  properly  described  (see  Salter  1863;  Elies  and  Wood  1902)  and  apparently  has  no 
associated  fauna  confirming  its  age.  It  was  referred  to  as  a subspecies  of  D.  octobrachiatus  by  Elies 
and  Wood  (1902).  Compared  with  D.  octobrachiatus , the  present  form  is  much  less  robust  and,  due 
to  the  lack  of  details  known  from  the  proximal  part  of  either  taxon,  their  phylogenetic  relationship 
is  unclear.  The  beds  containing  my  five-stiped  form  are  of  an  age  when  great  changes  took  place  in 


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PALAEONTOLOGY,  VOLUME  34 


the  graptolite  fauna,  including  not  only  the  loss  of  bithecae  along  several  lineages  but,  as  far  as  I 
have  seen,  also  an  instability  in  the  number  of  stipes  present  in  a specimen.  It  thus  seems  more 
probable  to  me  that  the  present  form  has  a derivation  separate  from  that  of  the  later  Dichograptus 
species. 


Family  sinograptidae  Mu,  1957 
Subfamily  sigmagraptinae  Cooper  and  Fortey,  1982 

Diagnosis  (from  Fortey  and  Cooper  1986):  Dichograptinids  with  sigmagraptine  proximal  region. 

Remarks.  The  Sigmagraptinae  was  originally  described  as  a subfamily  of  the  Dichograptidae  with 
included  species  united  by  the  characteristic  proximal  part  and  generally  slender  thecae.  The  taxon 
was  raised  to  family  rank  by  Fortey  and  Cooper  (1986),  consisting  of  the  nominate  subfamily  only. 
Williams  and  Stevens  (1988)  lowered  the  rank  back  to  subfamily  level,  and  included  it  in  the  family 
Sinograptidae.  I follow  the  classification  of  Williams  and  Stevens  (1988),  and  also  their  concept  of 
the  content  of  the  family  (sinograptines,  sigmagraptines,  and  the  previously  ‘obscure'  Kinnegraptus). 
The  use  of  the  name  Sinograptidae  follows  priority  rules,  even  though  a sigmagraptid  is  the  ancestor 
of  the  sinograptines. 

The  kinnegraptids  were  raised  to  family  rank  by  Mu  (1974)  and  were  used  at  this  level  for 
Paradelograptus  by  Erdtmann  et  al.  (1987).  Also  Williams  and  Stevens  (1988),  though  temporarily 
including  them  in  the  Sigmagraptinae,  considered  the  possibility  that  further  study  might  show  that 
the  kinnegraptids  merit  family  rank.  However,  my  own  investigations  have  shown  them  to  be  very 
close  to  the  main  stock  of  sigmagraptines.  Acrograptus  gracilis  has  an  equally  prolonged  prosicula, 
and  the  exaggerated  apertural  lip  (rutellum ; Williams  and  Stevens  1 988)  of  thecae  and  sicula  is  found 
among  some  of  the  Paradelograptus  species,  as  well  as  in  some  specimens  of  A.  tenellus  (Hutt  1974, 
fig.  8a),  the  species  which  must  be  considered  the  best  candidate  for  an  ancestor  of  the 
Sigmagraptidae. 


Genus  paradelograptus  Erdtmann,  Maletz  and  Gutierrez  Marco,  1987 

Diagnosis.  See  Erdtmann  et  al.  (1987).  The  most  important  features  mentioned  are  biradiality, 
irregular  dichotomies,  isograptid  development,  asymmetrical  proximal  part,  and  a characteristic 
thecal  shape  with  long  thin  prothecae  and  expanding  metathecae,  sometimes  provided  with 
‘lappets'  [here  meaning  ventral  prolongation].  Bithecae  were  not  observed. 

Remarks.  When  defined  by  Erdtmann  et  at.  (1987),  the  genus  Paradelograptus  was  referred  to  the 
family  Kinnegraptidae  Mu,  1974.  However,  the  authors  base  this  family  only  on  the  shape  of  the 
thecae,  disregarding  features  of  the  proximal  end  (1987,  p.  113):  ‘This  character  [shape  of  the 
proximal  part],  however,  is  not  a discriminating  factor  for  Paradelograptus  alone  nor  for  the 
Kinnegraptidae  and  Sigmagraptinae  [of  the  Dichograptidae],  as  was  suggested  by  Cooper  and 
Fortey  (1982,  p.  259),  but  it  is  observed  quite  frequently  in  many  other  dichograptids,  dating  back 
to  the  ancestral  Adelograptus  tenellus  (Hutt,  1974,  fig.  5 b,  Maletz  and  Erdtmann  1987)  and  to  other 
adelograptinid  forms  (i.e.  to  Choristograptus  Legrand,  1964).  Therefore , no  taxonomic  significance 
may  be  attached  to  this  feature  alone  [my  italics] '.  With  this  statement  I disagree.  In  my  opinion,  they 
have  defined  a group  of  genetically  related  taxa.  Further,  figure  2 of  Erdtmann  et  al.  ( 1 987),  showing 
the  ‘phyletic  relations'  of  taxa,  disagrees  with  the  text.  The  text  states  that  the  concepts  of  Cooper 
and  Fortey  ( 1982)  have  been  used,  that  is,  that  Sigmagraptinae  is  a subunit  of  Dichograptidae.  The 
figure,  on  the  other  hand,  shows  a possibly  diphy letic  Sigmagraptinae  branching  off  the 
Kinnegraptidae,  and  possibly  also  the  Clonograptinae. 

Paradelograptus  differs  from  Adelograptus  solely  in  the  absence  of  bithecae  along  the  stipes.  It 
includes  both  two-stiped  and  multi-stiped  taxa.  Among  the  Paradelograptus  species  described  by 
Erdtmann  et  al.  (1987)  the  proximal  development  is  known  only  for  the  type  species,  P.  onubensis. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  G R APTOLITES 


317 


It  is  quite  possible  that  the  genus  Paradelograptus , with  the  constituent  species  as  given  by 
Erdtmann  et  al.  (1987,  p.  115;  15  species  in  all,  those  mentioned  below  and  P.  sedecimus , P.  ranis , 
P.  smithi , P.  ramulosus , P.  chapmani , /\  ? tenuiramis,  P.  ? clarkefieldi,  P.  ? bulmani,  C.  tenellus  var. 
problematica  Harris  and  Thomas,  and  C.  tenellus  sd.  Cooper  and  Steward),  is  a polyphyletic 
assemblage  of  similar-looking  forms,  which  have  responded  in  a similar  way  to  peculiarities  of  the 
environment.  However,  the  external  shape  of  the  proximal  parts,  with  an  adelograptid  type  of 
sicula,  in  P.  onubensis , P.  antiquus , P.  pritchardi  and  P.  mosseboensis , and  P.  elongatus  and  P.  tenuis 
described  here,  is  so  similar  as  to  make  it  likely  that  at  least  this  group  is  monophyletic.  P. 
kinnegraptoides  appears  from  illustrations  not  to  have  an  adelograptid  sicula.  The  proximal 
development  of  P.  smithi  was  not  seen  in  the  specimens  from  Mt  Hunneberg,  and  the  inclusion  of 
that  species  by  Erdtmann  et  al.  (1987)  seems  to  be  based  on  thecal  morphology  alone. 

Two  new  species  are  described  here.  A number  of  other  species  present  in  the  Scandinavian  Lower 
Hunneberg  beds  are  mentioned  under  ‘Other  species’  (p.  320). 


Paradelograptus  elongatus  sp.  nov. 

Text-fig.  15  c,  g-i 

Name.  Latin  elongatus , elongated,  referring  to  the  long  first-order  stipes. 

Material.  16  specimens,  15  of  which  come  from  Slemmestad  (14  of  them  on  PMO  108.568-108.570, 
Slemmestad  crossroads;  1 specimen,  LR  2,  from  the  base  of  the  T.  phyllograptoides  Zone  at  Hagastrand,  Lund 
collections).  One  specimen  was  found  in  the  Krapperup  core  (124-87-1 24-89  m).  A questionable  specimen  was 
found  at  Storeklev  (2-32  nr,  Lund  collections).  Both  the  holotype  (Text-fig.  1 5 1 ; the  only  mature  specimen)  and 
the  paratypes  are  found  on  PMO  108.570. 

Associated  species.  A.  murrayi,  H.  copiosus , P.  antiquus. 

Stratigraphic  range.  H.  copiosus  Zone,  and  at  least  the  basal  beds  of  the  T.  phyllograptoides  Zone. 

Diagnosis.  Biradiate,  declined  to  pendent  in  profile  view,  branching  dichotomously  at  irregular 
intervals;  first-order  stipes  consist  of  more  than  one  theca.  Proximal  development  probably 
isograptid;  both  sinistral  and  dextral  forms  occur.  A sicular  bitheca  has  been  observed.  Metathecae 
somewhat  Hared,  but  less  so  than  in  P.  mosseboensis.  Dimensions  close  to  the  latter. 

Description.  The  sicula  is  straight  and  tube-like,  1 -9-2-0  mm  long  and  03-0-4  mm  wide  at  the  aperture.  Theca 
1 1 originates  close  to  the  apex  of  the  sicula.  The  development  is  probably  isograptid,  the  prothecal  part  of  th  21 
is  seen  in  the  specimen  in  Text-figure  15g,  and  can  be  traced  back  almost  to  the  point  of  origin  of  theca  l2. 
A sicular  bitheca  is  present  on  the  obverse  side  of  the  sicula  (Text-fig.  15  c).  There  are  both  dextral  and  sinistral 
forms.  The  thecae  are  2 mm  long  or  longer,  have  relatively  thin  prothecal  parts  and  somewhat  flaring 
metathecae,  which  are  sometimes  seen  to  have  a short  denticle.  Thecal  width  at  the  apertures  reaches 
0-4— 0-5  mm.  There  are  8-9  thecae  in  10  mm  and  the  thecal  overlap  is  about  40-50%  (the  point  of  origin  of 
thecae  is  commonly  obscure).  The  profile  stipe  width  is  0-6-0-7  mm  in  proximal  parts,  up  to  0-9  mm  in  distal 
parts.  The  first-order  stipes  vary  in  attitude  from  almost  horizontal  to  pendent,  if  seen  in  profile  view.  The  first 
dichotomy  occurs  at  th  3 or  later,  sometimes  considerably  later:  in  one  unbranched  specimen,  first-order  stipes 
have  8 and  14  thecae.  The  holotype  is  a mature  specimen  showing  five  orders  of  stipes,  the  greatest  number 
known.  There  is  a considerable  amount  of  cortical  strengthening  of  proximal  stipes  in  the  holotype,  giving  it 
a much  more  rigid  appearance  than  the  associated  smaller  specimens.  No  bithecae  have  been  observed  along 
the  stipes,  but  the  material  is  mostly  of  low  to  no  relief. 

Remarks.  P.  elongatus  most  closely  resembles  P.  mosseboensis , which  occurs  at  a considerably 
higher  level,  around  the  lower  boundary  of  the  D.  balticus  Zone  at  Diabasbrottet,  Hunneberg 
(Erdtmann  et  al.  1987,  fig.  1).  The  dimensions  of  the  two  species  are  virtually  the  same,  but  the 
ventral  thecal  processes  are  less  pronounced  in  P.  elongatus.  The  latter  is  widely  variable  in  the 
position  of  the  second-order  branching,  whereas  the  corresponding  range  for  P.  mosseboensis  was 


318 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  15.  For  legend  see  opposite. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


319 


indicated  as  theca  2-3  (Erdtmann  et  al.  1987,  p.  120).  This  range  might  be  considerably  wider,  since 
the  species  was  only  represented  by  three  incomplete  specimens.  The  holotype  of  P.  elongatus  very 
much  resembles  that  of  P.  kinnegraptoides  in  general  shape,  but  not  in  size  and  thecal  details. 


Paradelograptus  tenuis  sp.  nov. 

Text-fig.  1 5 a— b,  D— F 

? 1979  Clonograptus  tenellus  Linnarsson  s./.\  Cooper  and  Stewart,  pp.  785-786,  text-fig.  8 m. 

Name.  Latin  tenuis , thin,  small-sized. 

Material.  15  specimens,  13  of  which  come  from  various  localities  in  the  Slemmestad  area  (12  of  them,  some 
with  counterpart,  are  found  on  PMO  73.188-73.189,  73.191-73.192,  108.557-108.560,  108.566, 
112. 966-1 1 2 . 969,  113.031;  one  specimen,  LR  3,  from  the  base  of  the  T.  phyllograptoides  Zone  at  Hagastrand, 
Lund  collections).  The  other  two  specimens  are  from  Storeklev  (TUB  HUN-S/2. 18-2.3/006  + 030  and  036). 
Two  additional  questionable  specimens  from  Storeklev  were  found  on  PU  Vg  127  and  one  slab  in  the  Lund 
collections  (from  2-32  m).  The  holotype  is  a mature  specimen  on  PMO  108.566  (Text-fig  15a),  the  four 
paratypes,  all  illustrated  in  Text-figure  15,  are  found  on  PMO  108.557  108.559. 

Associated  species.  A.  murrayi , H.  copiosus , C.  alT.  multiplex , Isograptus  sp.,  horizontal  tetragraptids 
(‘quadribrachiatus’-type). 

Stratigraphic  range.  H.  copiosus  Zone  and  at  least  the  basal  beds  of  the  T.  phyllograptoides  Zone. 

Diagnosis.  A small,  thin  paradelograptid  with  tetragraptid  proximal  part  and  frequent  branchings. 
Sicula  1 -6-1 -9  mm  long,  7-5-8  thecae  in  10  mm,  profile  stipe  width  0-5-0-65  mm,  lateral  width 
0-2  mm  or  more. 

Description.  The  sicula  is  of  general  paradelograptid  shape,  1-6-1 -9  mm  long  and  0-3-0-4  mm  wide  at  the 
aperture.  The  two  stipes  diverge  from  the  sicula  at  different  levels,  stipe1  at  sicular  mid-length  or  slightly  closer 
to  the  aperture,  stipe2  leaving  0-2  mm  or  less  protruding  on  the  ventral  side  of  the  stipe.  The  first-order  stipes 
consist  of  one  theca  each  (resulting  in  a tetragraptid  proximal  plan),  the  second-order  ones  of  1-3  thecae.  The 
following  orders  each  get  a little  longer,  but  in  general  aspect,  the  rhabdosome  is  very  thin-stiped  and  rather 
densely  branching.  Six  orders  of  stipes  were  found  in  the  largest  specimen. 

The  thecae  have  very  low  inclination,  their  ventral  margins  are  concave,  and  they  are  denticulate.  The 
apertural  margins  are  straight  to  markedly  concave,  making  an  angle  of  90°  or  more  with  the  dorsal  margin 
of  the  stipes.  The  profile  stipe  width  is  0-5-0-65  mm  and  there  are  7-5—8  thecae  in  10  mm.  The  amount  of  thecal 
overlap  could  not  be  determined.  The  lateral  stipe  width  is  variable,  0 2-0-6  mm,  depending  above  all  on  the 
amount  of  cortex  overgrowth.  A noticeable  amount  of  cortex  cover  is  only  found  in  the  most  mature  specimen 
where,  due  to  slight  pyritization,  the  outline  of  the  stipes  can  be  traced  inside  the  cortex.  No  specimen  was  well 
enough  preserved  to  verify  presence  or  absence  of  bithecae.  Badly  preserved  stipe  fragments  appear  as  thin 
branching  ‘threads’  with  no  thecae  visible. 

Remarks.  The  size  and  shape  of  sicula  and  thecae  are  very  close  to  those  of  P.  elongatus  (see  Text- 
fig.  15).  However,  the  two  species  differ  in  branching  density  and  the  position  of  the  second 
dichotomy  (tetragraptid  proximal  part  only  in  P.  tenuis). 


text-fig.  15.  a-b,  d-f,  Paradelograptus  tenuis  sp.  nov.,  Slemmestad;  a,  holotype,  PMO  108.566,  the  largest 
specimen,  with  considerable  cortical  thickening;  b,  PMO  108.557-108.558,  horizontally  preserved  specimen; 
the  drawing  is  a combination  of  counterparts;  d,  PMO  108.559,  immature  specimen  with  (secondarily?) 
pendent  proximal  part;  e,  PMO  108.557;  f,  PMO  108.559,  combination  of  counterparts,  c,  G-i, 
Paradelograptus  elongatus  sp.  nov.,  Slemmestad,  all  on  PMO  108.570;  c,  specimen  showing  presumed  sicular 
bitheca;  G,  H,  specimens  showing  variation  in  proximal  stipe  attitude;  i,  holotype,  the  only  mature  specimen 
found;  the  sicula  points  downwards  into  the  sediment,  the  two  shortest  second-order  stipes  point  slightly 

upwards. 


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The  general  aspect  of  the  species  is  very  close  to  that  of  C.  tenellus  s.l.  sensu  Cooper  and  Stewart, 
1979,  from  the  La  2 zone  of  Victoria,  Australia.  The  distal  stipe  width  of  P.  tenuis  is  somewhat 
broader  and,  also,  no  cortical  thickening  was  mentioned  for  C.  tenellus  s.l.  There  is  a certain 
resemblance  in  shape  also  to  Adelograptus  altus  Williams  and  Stevens  (1991)  but,  due  to  the 
indifferent  preservation  of  the  mature  specimens  of  that  species  and  the  generalized  shape  of  the 
proximal  part  (similar  to  P.  elongatus , P.  tenuis  and  probably  other  species),  no  closer  comparison 
can  be  made. 


Other  species 

In  the  Early  Hunneberg  fauna  there  are  several  species  in  addition  to  the  ones  described  above.  Here,  they  are 
only  briefly  discussed  as  some  of  them  are  quite  well  known  from  other  areas,  others  are  hard  to  identify  due 
to  a fragmentary  preservation,  and  still  others  are  very  rare  and  are  not  diagnostic  of  the  fauna,  e.g.  horizontal 
tetragraptids. 

Clonograptids  s.l.  Several  specimens  of  a thin-stiped  Clonograptus  species  with  slightly  prolonged  first-order 
stipes  (Text-fig.  10b)  are  present  on  PMO  97.708,  from  the  Slemmestad  area,  together  with  Tetragraptus  longus 
sp.  nov.  The  species  is  very  similar  in  outline  to  Clonograptus  rigidus , but  it  appears  to  be  thinner  and  the  thecae 
are  not  well  enough  preserved  for  a definite  identification. 

Clonograptus  ( Clonograptus ) aff.  multiplex  (PMO  108.557-108.559)  occurs  at  Slemmestad  and  in  the  T. 
phyllograptoides  Zone  of  Mt  Hunneberg.  It  was  described  by  Lindholm  and  Maletz  (1989). 

Robust  stipe  fragments  probably  belonging  to  Clonograptus  s.s.  (Text-fig.  1 0 e)  occur  at  a couple  of  levels 
low  in  the  Krapperup  core.  A cortex-covered  specimen  was  found  in  the  Slemmestad  area  (PMO  113.032).  It 
may  belong  to  Clonograptus  norvegicus. 

Horizontal  tetragraptids.  These  are  extremely  rare  below  the  T.  phyllograptoides  Zone  in  the  Krapperup 
succession:  two  very  badly  preserved  specimens  of  tetragraptid  outline  ('quadribrachiatus’-type)  were  found 
at  152-89-93  m (LR  4-5),  a level  which  probably  equals  a very  early  Hunneberg  age.  The  longest  stipe  of  the 
larger  specimen  is  15  mm.  No  thecal  details  are  visible  in  this  specimen,  but  a stipe  of  the  other  specimen, 
preserved  in  relief,  seems  to  show  a plaited  thecal  structure.  Apart  from  this,  only  a possible  immature  specimen 
was  found  at  131  -70—1 31-73  m. 

In  the  Storeklev  section  at  Mt  Hunneberg  I have  not  found  any  tetragraptids.  However,  two  specimens  of 
‘ Eotetragraptus  sp.  1 ’ were  reported  by  Maletz  (1987;  the  stratigraphic  level  most  likely  corresponds  to  low 
T.  phyllograptoides  Zone).  Thecal  characters  were  not  observable. 

Tetragraptids  are  somewhat  more  frequent  along  with  the  Hunnegraptus  fauna  of  Norway.  Six  specimens  of 
varying  stipe  width  have  been  found  in  the  Slemmestad  area  (PMO  108.560,  108.569+  108.570,  112.968, 
1 12.969,  120.751,  and  one  specimen  in  the  Lund  collections).  Text-figure  1 4 1 illustrates  the  broadest  specimen 
found.  It  is  in  moderate  relief,  but  the  irregularities  seen  in  the  lower  right  of  the  figure  are  hard  to  interpret: 
do  they  represent  a plaited  thecal  structure  or  merely  the  effects  of  compression?  A 3 mm  wide  stipe  fragment 
of  tetragraptid  appearance  was  found  on  PMO  108.599. 

Pendent  didymograptids.  A small  pendent  (or  immature  deflexed?)  didymograptid  species  (Text-fig.  14c,  f)  has 
been  found  in  the  highest  beds  of  the  early  Hunneberg  fauna,  just  below  the  base  of  the  T.  phyllograptoides 
Zone.  It  is  the  most  diagnostic  species  of  this  interval.  It  occurs  at  1 18.54-1  12.75  m in  the  Krapperup  core 
(47  specimens;  the  majority  of  them  associated  on  a couple  of  surfaces  and  too  badly  preserved  to  form  the 
basis  of  a description),  and  a few  specimens  were  also  found  both  at  Mt  Hunneberg  and  in  the  Slemmestad 
area. 

Isograptids.  Primitive  isograptids  have  been  found  in  the  H.  copiosus  Zone  in  the  Slemmestad  area.  These  are 
apparently  the  oldest  isograptids  found  anywhere.  They  will  be  described  in  a separate  paper  (Lindholm  in 
prep.).  The  oldest  specimens  have  isograptid  symmetry,  but  much  less  reclined  stipes  than  the  majority  of 
isograptids.  They  also  possess  a sicular  bitheca.  An  additional  specimen  was  found  at  125.67-69  m of  the 
Krapperup  core. 

Paradelograptids  (Erdtmann  et  al.  1987).  Par  adelograptus  is  represented  by  several  species,  especially  in  the 
Krapperup  core,  see  Text-figure  16. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


321 


text-fig.  16.  Paradelograptus  species  present  in  the  topmost  Tremadoc  and  lower  Hunneberg  of  Scandinavia, 
but  not  described  in  this  paper,  a,  d,  P.  pritchardi  (T.  S.  Hall),  two  associated  specimens,  Krapperup  core 
1 34-20—  1 34-26  m;  a,  LO  5999t ; d,  LO  6000t,  the  stipes  are  slightly  twisted,  b,  P.  antiquus  (T.  S.  Hall),  LO  6301 1, 
Storeklev.  c,  P.  sp.  I,  PMO  1 12.967,  Slemmestad.  e,  P.  onubensis  Erdtmann,  Maletz  and  Gutierrez  Marco,  LO 
600 1 1,  Krapperup  core  151-46—151-50  m.  F,  P.  sp.  2,  LO  6002t,  Krapperup  core,  153  20-153-29  m.  G,  h,  P.  sp. 
3,  LO  6003t  and  6004t,  Krapperup  core  151-96-451-99  m;  the  specimens  are  associated,  i,  P.  cf.  rarus  (Harris 
and  Thomas),  LO  6302t,  Storeklev.  j,  k,  P.  sp.  4;  j,  LO  6005t,  Krapperup  core  141-75  m;  k,  LO  6006t, 
Krapperup  core  150-71-150-75  m.  l,  P.  sp.  5,  LO  6007t,  Krapperup  core  1 53-20  1 53-29  m.  m,  n,  P.  sp.  6;  m, 
LO  6008t,  Krapperup  core  148-79  m;  n,  LO  6009t,  Krapperup  core  1 50-7 1—1 50-75  m. 


One  specimen  of  P.  onubensis  was  found  at  151  -46—1 5 1-50  m.  It  is  rather  immature,  with  only  two  stipes,  but 
the  shape  of  the  proximal  part  is  unmistakable  (Text-fig.  1 6 e).  A second  specimen  was  found  at 
1 1 1 40-1 1 1 45  m. 

P.  pritchardi  ( Text-fig.  16  a,  d)  occurs  in  the  135  09  1 18-50  m interval.  P.  antiquus  (Text-fig.  16  b)  was  found 
between  1 17-88  and  114-17  m of  the  Krapperup  core.  The  species  is  also  represented  at  Storeklev  (LO  630 It, 
TUB  HUN-S/2. 18-2.3/023,  PU  Vg  124,  and  one  specimen  in  the  Lund  collections),  at  Toyen  (GP1  T4,  T6), 
and  at  Slemmestad  (PMO  108.568.  108.572,  one  specimen  in  the  Lund  collections). 

Stipe  fragments  indistinguishable  from  P.  rarus  (Text-fig.  1 6 1 ) were  found  at  Storeklev  (LO  6302t  and 
counterpart ; one  specimen  in  the  Lund  collections)  and  Slemmestad  (PMO  108 . 567,  109  . 148).  Stipes  probably 
belonging  to  the  same  species  are  not  uncommon,  but  the  thecal  outline  needed  for  identification  is  seldom 
seen. 

In  addition  to  these  species,  unidentifiable  proximal  parts  and  stipe  fragments  occur  in  the  Krapperup  core 


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text-fig.  17.  Graptoloidea  indet.  spp.  Relief  specimens,  all  (and  more)  associated  on  one  surface,  near  the  base 
of  the  A.  murrayi  Zone,  Krapperup  core  1 47-66—147-72  m,  LO  60 1 Ot— 60 1 4t.  a-d  show  the  sicular  bitheca;  d 
shows  a bitheca  in  stipe  1.  e could  be  interpreted  as  triradiate.  c was  drawn  from  a latex  cast;  e was  combined 
from  both  counterparts.  All  illustrations  were  made  under  vertical  light. 


in  the  interval  1 53-29—  1 34-20  m.  Some  of  them  are  illustrated  in  Text-figure  16f-h,  j-n.  One  of  the  species  is 
minute  - its  sicula  is  only  0-3  mm  long  (Text-fig.  16  m,  n). 

Relief  specimens  of  unknown  affinity.  Text-figures  17  and  18  show  some  of  the  immature  relief  specimens  of 
various  kinds  that  have  been  found  at  two  levels  in  the  Krapperup  core,  1 47-66—147-72  m and  1 32-63—1 32-66  m, 
i.e.  close  to  the  bases  of  the  A.  mwravi  and  H.  copiosus  Zones.  At  both  levels  all  specimens  in  obverse  view 
show  a sicular  bitheca.  The  stipes  are  mostly  too  incomplete  to  show  presence  or  absence  of  bithecae. 
Specimens  with  bithecate  stipes  are  present  at  the  lower  level  (Text-fig.  17d),  as  well  as  possibly  triradiate  forms 
(Text-fig.  1 7 h).  The  specimens  are  of  extensiform,  declined,  and  pendent  types.  Because  stipes  are  incomplete, 
it  is  also  difficult  to  say  how  many  branchings  the  mature  specimens  would  have  had,  but  some  of  the  pendent 
forms  may  belong  to  A.  murrayi  (Text-fig.  18c). 

Kiaerograptids  or  didymograptids?  The  lower  part  of  the  Krapperup  core,  mainly  below  the  level  of  the 
Hunnegraptus  fauna,  contains  several  badly  preserved  specimens  that  are  declined  to  deflexed.  They  are  seldom 
very  big,  mostly  containing  5 thecae  per  stipe  or  less,  but  it  seems  unlikely  that  they  would  have  branched 
further,  had  they  lived  longer.  Because  of  their  flatness  (bithecae  undetectable)  and  the  short  stipes 
(immaturity),  their  identity  is  uncertain. 

The  earliest  T.  phyllograptoides.  This  species  does  not  belong  in  the  fauna  under  discussion,  but  is  present  in 
the  succeeding  T.  phyllograptoides  Zone.  It  appears  right  at  the  base  of  its  zone  in  Slemmestad,  but  some  of 
the  earliest  specimens  found  there,  in  the  lowermost  metre,  deviate  from  the  typical  form  described  by  Cooper 
and  Lindholm  (1985).  As  seen  in  Text-figure  14e,  h,  some  of  the  specimens  could  be  three-stiped.  Preparation 
gave  no  evidence  of  a fourth  stipe.  The  atypical  specimens  also  differ  in  having  considerably  narrower  stipes 
( T3-T6  mm)  and  fewer  thecae  (2-4)  in  the  conjoined  part  of  the  stipes.  Only  one  specimen  with  normal  width 
of  stipes  was  found  in  the  lowermost  horizon  at  Grundvik,  Slemmestad.  Some  specimens  also  have  slightly  less 
strongly  reclined  stipes. 

So  far,  only  13  specimens  (all  belonging  to  the  Lund  collections)  have  been  found  this  low,  at  three  different 
localities,  in  the  Slemmestad  area:  3 specimens  from  6-25  m above  the  Ceratopyge  Limestone  at  Hagastrand; 
8 specimens  from  2-50  m above  the  missing  part  at  Grundvik  ( c . 10  cm  higher  than  Hagastrand)  and  one 
specimen  12  cm  higher;  finally  one  specimen  from  about  80  cm  higher  than  the  lowest  Grundvik  level  at  the 
Rortunet  section. 

In  the  Krapperup  core,  some  weakly  reclined  tetragraptids  are  found  a couple  of  metres  below  the  first  find 
of  T.  phyllograptoides.  They  are  mostly  very  short-stiped,  and  no  species  identification  has  been  attempted. 


LINDHOLM:  SCANDINAVIAN  ORDOVICIAN  GRAPTOLITES 


323 


text-fig.  18.  Relief  specimens,  all  (and  more)  associated  on  one  surface,  near  the  base  of  the  H.  copiosus  Zone, 
Krapperup  core,  1 32-63-1 32-66  m,  LO  6085t-6095t.  a,  b,  d,  e,  g,  i,  k,  Graptoloidea  indet.  spp;  b shows  a 
typical  symmetrical  pair  formed  by  the  sicula  and  th  l1,  with  the  bitheca  in  the  centre;  e has  no  bithecae  along 
the  stipes;  i shows  th  l1  growing  around  the  sicula;  in  k,  the  proximal  part  is  a mould;  all  specimens  in  obverse 
view  show  a sicular  bitheca,  c,  'lAraneograptus  murrayi  (J.  Hall),  the  stipes  are  of  dichograptid  type,  f,  j,  H. 
copiosus  sp.  nov.  h,  cf.  H.  copiosus.,  the  apex  of  the  sicula  points  somewhat  downwards.  J and  k were  made 
from  latex  casts,  c and  e from  combinations  of  counterparts.  All  illustrations  were  made  under  vertical  light. 


324 


PALAEONTOLOGY,  VOLUME  34 


Acknowledgements . I thank  Roger  Cooper  and  Anita  Lofgren  for  valuable  discussions  and  linguistic  help,  and 
Gerhard  Regnell  for  advice  on  Latin  names.  David  Bruton,  Adrian  Rushton  and  Jorg  Maletz  made  useful 
comments  on  the  manuscript.  Nils  Spjeldnaes  and  Bernd-Dietrich  Erdtmann  kindly  made  their  collections 
available  for  study,  and  Henry  Williams  gave  me  access  to  a manuscript  prior  to  publication.  The  following 
have  assisted  in  the  loan  of  specimens:  David  Bruton  and  Gunnar  Henningsmoen  (PMO),  Bjorn  Neuman 
(Bergen),  Valdar  Jaanusson  (RM),  Sven  Laufeld  and  Sven-Ola  Nilsson  (SGU),  and  Solveig  Stuenes  (PU).  Jorg 
Maletz  provided  the  photograph.  I also  want  to  thank  all  my  field  assistants  through  the  years.  Financial  help 
has  been  given  by  the  Swedish  Natural  Science  Research  Council,  NFR  (project  ‘Early  Ordovician 
Biostratigraphy’),  Lunds  Geologiska  Faltklubb,  and  Gyllenstiernska  Krapperupsstiftelsen. 


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— 1904.  Researches  into  the  graptolites  of  the  lower  zones  of  the  Scanian  and  Vestrogothian  Phyllo- 
Tetragraptus  beds,  part  2.  Lunds  Universitets  Arsskrift , 40(1:  2),  1-29,  pis  1-4. 

tullberg,  s.  a.  1880.  Nagra  Didymograptusarter  i undre  graptolitskiffer  vid  Kiviks-Esperod.  Geologiska 
Fbreningens  i Stockholm  Forhandlingar , 5,  39-43,  pi.  2. 
wang  gang.  1981.  On  the  discovery  of  new  graptolites  from  the  Tungtze  Formation  (Lower  Ordovician)  in 
Gulin  of  Sichuan.  Acta  Palaeontologica  Sinica,  20,  349-352,  pi.  1.  [In  Chinese  with  English  abstract], 

WHITTINGTON,  H.  B.,  DEAN,  W.  T.,  FORTEY,  R.  A.,  RICKARDS,  R.  B.,  RUSHTON,  A.  W.  A.  and  WRIGHT,  A.  D.  1984. 
Definition  of  the  Tremadoc  Series  and  the  Series  of  the  Ordovician  System  in  Britain.  Geological  Magazine , 
121,  17-33. 

williams,  s.  H.  and  stevens,  R.  k.  1988.  Early  Ordovician  (Arenig)  graptolites  of  the  Cow  Head  Group,  western 
Newfoundland,  Canada.  Palaeontographica  Canadiana , 5,  1-167. 

1991.  Late  Tremadoc  graptolites  from  western  Newfoundland.  Palaeontology , 34,  1^17. 
zalasiewicz,  j.  a.  1986.  Graptolites  from  the  type  Arenig  Series.  Geological  Magazine , 123,  537-544. 

KRISTINA  LINDHOLM 

Department  of  Historical  Geology  and  Palaeontology 
Typescript  received  5 December  1989  Solvegatan  13, 

Revised  typescript  received  5 March  1990  S-223  62  Lund,  Sweden 


TRILOBITES  FROM  THE  ORDOVICIAN  OF 

PORTUGAL 

by  M.  ROMANO 


Abstract.  The  following  trilobite  species  from  the  Llanvirn  to  Llandeilo  of  north  and  central  Portugal  are 
recorded  or  described  and  their  stratigraphical  ranges  are  discussed:  Colpocoryphe  aff.  rouaulti  (Henry), 
C.  cf.  thoralis  conjugens  Hammann,  C.  grandis  (Snajdr),  Salterocoryphe  salleri  salteri  (Rouault),  Prionocheilus 
mendax  (Vanek),  P.  cf.  pulcher  (Barrande)  and  Valongia  wattisoni  (Curtis).  Actinopeltis  tejoensis  sp.  nov.  and 
Prionocheilus  costai  (Thadeu)  from  the  upper  Ordovician  of  central  Portugal  are  described.  Salterocoryphe 
lusitanica  (Thadeu)  is  put  into  synonymy  with  Salterocoryphe  salteri  salteri ; Prionocheilus  cf.  pulcher  is 
recorded  for  the  first  time  from  Portugal;  authorship  of  Prionocheilus  costai  is  here  attributed  to  Thadeu  and 
a lectotype  is  chosen.  The  faunas  show  similarities  with  those  in  central  Iberia  and  northwest  France. 

Calymenid,  cheirurid  and  bathycheilid  trilobites  form  an  important  element  of  the  Ordovician 
faunas  of  Portugal.  As  early  as  1849,  Sharpe  noted  the  presence  of  ‘ Calymene  Tristani ' and 
‘ Cheirurus ' from  Valongo  (Text-fig.  1),  and  some  years  later  Ribeiro  (1853)  recorded  ‘'Calymene 
Tristani'  and  ‘ Calymene  Arago ' from  Buqaco.  Delgado  (1897,  p.  28;  1908,  pp.  57,  80,  106)  listed 
six  species  of  ‘ Calymene'  from  the  Ordovician  of  Buqaco,  Amendoa/Maqao  and  Valongo,  but  did 
not  describe  or  figure  any  of  the  material.  Subsequently,  Costa  (1942)  published  a short  account  on 
the  Calymenidae  in  which  he  figured  ‘ Calymene  Tristani'  and  ‘ Calymene  Salteri'  from  Valongo. 
More  recently  Thadeu  (1947)  revised  some  of  the  upper  Ordovician  trilobites  from  Buqaco,  among 
which  he  described  and  figured  the  following  species  of  ‘ Cheirurus' : ‘ {l)Bocagei,  claviger , 
gelasinosus,  ( ?) Venceslasi,  aff.  completus  and  aff.  verrucosus',  as  well  as  ‘ Pharostoma  costai'.  Two 
years  later  Thadeu  (1949)  revised  the  Portuguese  calymenids  and  recognized  five  species  of 
‘ Synhomalonotus'  C Aragoi , Salteri , Tristani , transiens,  lusitanica')  and  two  of  ' Pharostoma ' 
(‘  Costai , pulchra').  South  of  the  River  Douro,  along  an  extension  of  the  Valongo  outcrops,  Thadeu 
(1956)  again  recorded  the  species  ‘ aragoi ' and  'tristani',  as  well  as  ' Calymeme  cf.  duplicata' . Curtis 
(1961)  described  Actinopeltis  wattisoni  from  the  Valongo  area. 

The  present  paper  revises  the  taxonomy  and  distribution  of  the  following  genera  from  the 
Ordovician  of  Portugal:  Colpocoryphe , Salterocoryphe , Prionocheilus , Actinopeltis  and  Valongia. 
Most  of  the  material  is  restricted  stratigraphically  to  beds  of  Llanvirn  to  early  Caradoc  age;  only 
Prionocheilus  costai  (Thadeu,  1947)  is  of  late  Caradoc-?Ashgill  age. 

Material  used  is  housed  in  the  collections  of  the  Geological  Survey  offices,  Lisbon  (prefixed  SG 
or  MR)  and  Earth  Sciences  Unit,  University  of  Sheffield  (prefixed  P or  RC).  Further  material  was 
kindly  made  available  by  Dr  A.  H.  Cooper  (Cooper  1980)  and  Dr  T.  P.  Young  (Young  1985; 
prefixed  ABO,  CST,  LOR,  MDC,  PEN,  PG  and  QXP,  at  present  in  the  Geology  Department, 
University  College  of  Cardiff). 


STRATIGRAPHY 

The  material  studied  is  mainly  from  the  major  outcrops  of  fossiliferous  rocks  in  Portugal;  namely 
Valongo  to  Arouca,  Buqaco  to  Rio  Ceira,  and  Domes  to  Amendoa/Maqao  (Text-fig.  1).  The 
simplified  stratigraphic  columns  in  Text-figure  2 illustrate  the  major  lithotypes,  formations  and 
members  of  these  regions.  More  detailed  descriptions  of  the  rock  units  may  be  found  in  Romano 


IPalaeontology,  Vol.  34,  Part  2,  1991,  pp.  329-355,  4 pls.| 


© The  Palaeontological  Association 


330 


PALAEONTOLOGY, VOLUME  34 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


331 


text-fig.  2.  Generalized  lithostratigraphic  sections  for  north  Portugal  (Valongo-Arouca)  and  central  Portugal 
(Bugaco,  Bupaco-Rio  Ceira,  Dornes-Amendoa/Mapao). 


332 


PALAEONTOLOGY, VOLUME  34 


and  Diggens  (1976),  Henry,  Nion  et  al.  (1976),  Mitchell  (1974),  Cooper  (1980),  Brenchley  et  al. 
(1986)  and  Young  (1985,  1988). 

A brief  resume  is  given  here  of  the  successions  shown  in  Text-figure  2.  The  Llanvirn  Llandeilo 
sequence  at  Valongo  to  Arouca  is  a monotonous  sequence  of  mudrocks  overlying  the  Armorican 
Quartzite.  The  mudrocks  (Valongo  Formation)  are  abruptly  succeeded  by  quartzites,  above  which 
are  pebbly  siltstones  and  sandstones  of  the  Sobredo  Formation.  This  latter  unit  is  of  glaciogenic 
origin  and  is  probably  of  late  Ordovician  (Hirnantian)  age.  The  region  between  Bugaco  and  Rio 
Ceira  shows  a general  homogeneity  and  differs  significantly  in  detail  from  the  Valongo  sequence. 
Young  (1985,  1988)  has  recently  revised  the  lithostratigraphy  of  this  region  above  the  Monte  da 
Sombadeira  Formation  (Brenchley  et  al.  1986)  and  his  terminology  is  incorporated  in  Text-figure 
2.  Graptolitic  mudstones  of  Llanvirn  age  are  known  from  the  Brejo  Fundeiro  Formation  (Cooper 
1980)  and  diverse  Llandeilo  faunas  occur  in  the  Fonte  da  Horta  Formation.  The  base  of  the 
Llandeilo  is  within  the  upper  part  of  the  Brejo  Fundeiro  Formation,  and  the  Carregueira 
Formation  is  probably  of  early  Caradoc  age  (Young  1988).  The  Louredo  Formation  is  entirely 
Caradoc  in  age;  the  fossiliferous  basal  Favagal  Bed  is  considered  to  be  of  early  Caradoc  age  (Henry 
and  Thadeu  1971 ; Henry,  Nion  et  al.  1976;  Paris  1979,  1981),  while  the  faunas  from  the  uppermost 
mudstone  unit  (Galhano  Member)  indicate  an  upper  Caradoc  age  (Paris  1979,  1981 ; Young  1988). 
The  overlying  Porto  de  Santa  Anna  Formation  contains  a rich  fauna  in  the  basal  Leira  Ma  Member. 
Mitchell  ( 1974)  attributed  an  early  Caradoc  age  to  this  assemblage  but  later  authors  have  suggested 
a late  Caradoc/early  Ashgill  age.  Young  (1988)  suggested  a possible  Rawtheyan  age  for  the  upper 
part  of  the  Porto  de  Santa  Anna  Formation.  In  the  southern  part  of  the  Bugaco  to  Rio  Ceira  region 
the  Porto  de  Santa  Anna  Formation  is  replaced  by  a sequence  of  massive  dolomites;  in  the  extreme 
south  around  Rio  Ceira,  clastic  sequences  overlie  an  attenuated  Porto  de  Santa  Anna  Formation 
and  are  succeeded  by  pebbly  siltstones  of  the  Casal  Carvalhal  Formation. 

The  final  column  in  Text-figure  2 represents  the  sequences  around  Domes  and  Amendoa/Magao. 
The  units  here,  up  to  the  Favagal  Bed,  are  essentially  similar  to  those  around  Bugaco.  In  the  lower 
part  of  the  Cabego  do  Peao  Formation,  however,  is  a richly  fossiliferous  unit,  termed  the 
Queixoperra  Member  (Young  1988),  of  early  Caradoc  age  (includes  the  Bryozoa  Beds  of  Cooper 
1980).  Poorly  fossiliferous  sequences  overlie  the  Cabego  do  Peao  Formation  in  this  southern  region, 
but  the  pebbly  siltstones  of  the  Casal  Carvalhal  Formation  may  be  correlated  with  those  of  the  Rio 
Ceira  section  and  probably  the  Sobredo  Formation  at  Valongo.  The  upper  part  of  the  Vale  da  Ursa 
Formation  (Cooper  1980;  Young  1988)  contains  graptolites  indicating  an  early  Llandovery  age. 


REMARKS  ON  THE  VERTICAL  RANGES  AND  GEOGRAPHICAL  DISTRIBUTIONS 

OF  THE  TRILOBITE  FAUNAS 


Vertical  ranges 

Colpocoryphe  aff.  rouaulti  Henry,  1970.  This  species  is  first  known  from  the  upper  Llanvirn  where 
it  is  present  approximately  30  m above  the  top  of  the  'Armorican  Quartzite’  in  the  Domes  area 
(Cooper  1980)  and  persists  at  least  into  the  Lower  Llandeilo  (Text-fig.  3).  A broadly  similar  range 
is  known  for  C.  rouaulti  in  Spain  (Hammann  1983;  Gutierrez-Marco  et  al.  1984),  and  in  Brittany 
it  is  known  to  occur  from  the  upper  Llanvirn  to  the  Marrolithus  bureaui  biozone  (Henry  1 980c/  and 
pers.  comm.)  where  it  is  common  south  of  Rennes  (Traveusot  Formation)  but  rare  in  the  upper  part 
of  the  Postolonnec  Formation  in  the  Crozon  Peninsula  (Henry  1980a). 

Colpocoryphe  cf.  thorali  conjugens  Hammann,  1983.  This  species  first  appears  less  than  one  metre 
above  the  Armorican  Quartzite  Formation  in  the  Bugaco  syncline  where  it  is  of  early  Llanvirn  age 
(Romano  et  al.  1986);  its  upper  range  limit  has  not  yet  been  established  in  Portugal.  In  northeast 
Portugal  it  has  been  recorded  from  near  Moncorvo  (Text-fig.  1 ) in  beds  low  down  in  the  Xistenta 
Formation  (Rebelo  and  Romano  1988)  where  it  is  probably  of  Llanvirn  age.  Thadeu  (1956,  p.  19, 
pi.  6,  fig.  1)  recorded  C.  aragoi  from  the  Canelas  quarries  at  Arouca,  south-east  of  Valongo.  The 
specimen  figured  by  Thadeu  is  poorly  preserved  but  Henry  (1970,  p.  13)  tentatively  assigned  it  to 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


333 


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text-fig.  3.  Sections  showing  ranges  of  graptolite  and  trilobite  species.  Abbreviations  refer  to  lithostratigraphic  units  shown  in  Text-figure  2. 


334 


PALAEONTOLOGY, VOLUME  34 


C.  rouaulti.  I have  not  seen  Thadeu's  specimen  but  have  collected  further  material  from  the  quarries 
which  include  Salterocoryphe  sp.  (possibly  5.  salteri  salteri).  Thadeu  mentioned  the  presence  of 
furrows  on  the  pleural  lobes  of  the  pygidium  of  the  Arouca  specimens  which  suggests  that  it  may 
be  better  assigned  to  Salterocoryphe ; the  details  of  the  preglabellar  area  are  not  easy  to  distinguish 
from  Thadeu's  figure  but  the  apparently  bell-shaped  glabella  is  reminiscent  of  S.  salteri  salteri.  The 
age  of  the  Canelas  quarries  assemblage  was  regarded  as  Llandeilo  by  Thadeu  but  the  presence  of 
Hungioides  bohemicus  (see  Rabano  1983),  Bathycheilusl  castilianus  and  Nobiliasaphus  caudiculatus, 
as  well  as  poorly  preserved  pendent  didymograptids,  suggests  a Llanvirn  and  possibly  early 
Llanvirn  age  (Gutierrez-Marco  et  al.  1984).  Courtessole  et  al.  (1981)  assigned  C.  thorali  thorali 
(Dean,  1966),  from  the  Lower  Arenig  of  the  Montagne  Noire,  to  Salterocoryphe  but  this  is  not 
accepted  here. 

Colpocoryphe  grandis  (Snajdr,  1956).  This  species  in  Portugal  appears  to  be  restricted  to  the  lower 
Caradoc  and  first  makes  its  appearance  in  the  Carregueira  Formation  in  central  Portugal.  It  is  last 
recorded  from  the  Queixoperra  Member  of  the  Cabeqo  do  Peao  Formation,  some  15-20  m above 
the  Favagal  Bed.  The  species  has  a greater  stratigraphic  range  in  Brittany  (Henry  1980a)  where  it 
is  known  from  the  top  of  the  Postolonnec  Formation,  Schistes  de  Raguenez  and  Riadan  Formation. 
In  Spain,  Rabano  (1984)  records  it  only  from  the  Caradoc  but  I have  collected  a deformed  cephalon 
of  Colpocoryphe  from  just  above  the  Los  Rasos  sandstones  (equivalent  to  the  Monte  de  Sombadeira 
Formation)  in  the  Guadarranque  area,  Toledo  Mountains,  central  Spain,  which  is  very  close  to  C. 
grandis.  Hammann  (1983,  unit  6 in  Guadarranque  section)  considered  this  horizon  to  be  of 
Llandeilo  age  and,  if  the  identification  proves  to  be  correct,  thus  possibly  extends  the  range  of  this 
species  in  Spain  to  approximately  equal  to  that  in  Bohemia,  where  it  is  of  Llandeilo-Caradoc  age 
(Dobrotiva,  Liben  and  Letna  Formations,  see  Havlicek  and  Vanek  1966). 

Salterocoryphe  salteri  salteri  (Rouault,  1851).  This  species  definitely  occurs  in  beds  of  Llandeilo  age 
from  the  upper  part  of  the  Valongo  formation  in  north  Portugal,  but  as  yet  I have  not  recorded 
undoubted  specimens  from  the  Llanvirn.  However,  at  Arouca,  a single  pygidium  from  the  lower 
part  of  the  Valongo  Formation  (probably  early  Llanvirn)  is  tentatively  identified  as  S.  salteri  salteri. 
Delgado  (1908,  pp.  134,  137  and  138)  questionably  identified  the  species  from  the  ‘Schistes  a 
Didymograptus ’ (lower  part  of  the  Valongo  Formation  and  considered  by  Gutierrez-Marco,  fide 
Hammann  et  al .,  1986  to  be  of  early  Llanvirn  age),  but  this  material  has  not  been  seen  by  the  author. 
In  Spain  the  species  occurs  in  the  Llanvirn  at  Guadarranque  and  much  of  the  Llandeilo  of  Corral 
de  Calatrava  and  El  Centenillo  (Hammann  1983;  Gutierrez-Marco  et  al.  1984),  while  in  Brittany 
it  appears  to  be  restricted  to  the  Llandeilo  (Henry  1980a)  where  it  occurs  south  of  Rennes,  on  the 
northern  flank  of  the  Laval  syncline  and  only  very  rarely  in  the  western  part  of  the  median  syncline. 

Prionocheilus  mendax  (Vanek,  1965).  The  range  of  this  species  in  Portugal  parallels  that  of  S.  salteri 
salteri ; it  is  of  Llandeilo  age  at  Valongo  but  possibly  extends  down  into  the  Llanvirn  (Delgado  1908, 
pp.  57,  106).  In  Bohemia  it  ranges  from  the  Llandeilo  to  lower  Caradoc  (Vanek  1965)  while  in 
central  Spain  and  Brittany  it  is  exclusively  of  Llandeilo  age  (Rabano  1984;  Henry  1980a). 

Prionocheilus  cf.  pulcher  (Barrande,  1846).  This  species  has  so  far  only  been  recorded  from  the 
Caradoc  of  the  Dornes-Amendoa/Ma?ao  region  and  as  far  as  I am  aware  does  not  occur  in  Spain. 
In  Brittany  it  has  only  tentatively  been  recorded  from  the  lower  Caradoc  although  Dr  J.-L.  Henry 
informs  me  that  there  are  differences  in  that  the  French  specimen  shows  shorter  and  straighter 
spines  on  the  cephalic  border  than  either  P.  pulcher  or  P.  verneuili.  In  Bohemia  it  has  a range 
throughout  much  of  the  Caradoc. 

Prionocheilus  costai  (Thadeu,  1947).  This  species  in  central  Portugal  is  so  far  only  known  from 
beds  of  late  Caradoc  or  early  Ashgill  age  and  is  probably  of  a similar  age  in  Spain  (Hammann  1983) 
where  it  is  known  from  the  ‘Bancos  mixtos’.  It  is  also  present  in  dropstones  from  the  basal  part  of 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


335 


the  Casal  Carvalhal  Formation  at  Domes  (Dr  T.  P.  Young  pers.  comm.)-  In  Brittany  it  occurs  in 
the  lower  part  of  the  Rosan  Formation. 

Actinopeltis  tejoensis  sp.  nov.  This  species  is  only  known  from  the  Queixoperra  Member, 
Amendoa/Maqao  region,  of  Caradoc  age.  The  genus  is  recorded  from  Spain,  from  the  Caradoc 
(Flammann  1972;  Rabano  1984),  and  also  from  the  Rosan  Formation  of  Brittany  (J.-L.  Henry  pers. 
comm.). 

Valongia  wattisoni  (Curtis,  1961).  This  monospecific  genus  is  at  present  only  known  from  the 
Llandeilo  of  Valongo. 

Geographical  distributions 

The  distribution  of  the  species  described  in  this  paper  substantiates  the  previously  documented 
contrast  found  in  the  composition  of  the  trilobite  faunas  in  north  (Valongo-Arouca,  Marao, 
?Moncorvo)  and  central  (Buc;aco-Amendoa/Maqao)  Portugal  throughout  much  of  the  Ordovician 
(Hammann  and  Henry  1978;  Henry  and  Romano  1978;  Romano  1982).  For  example,  during  the 
lower  Llandeilo  Salter ocoryphe  salteri  saltern  Prionocheilus  mendax  and  Valongia  wattisoni  are  only 
known  from  the  'northern’  region,  while  Colpocoryphe  aff.  rouaulti  is  apparently  restricted  to  the 
'southern'  region  (although  an  imperfectly  preserved  specimen  of  IColpocoryphe  is  known  from  the 
upper  part  (Llandeilo)  of  the  Valongo  Formation  in  the  north).  During  Caradoc-Ashgill  times, 
trilobite  faunas  are  at  present  unknown  in  north  Portugal  but  C.  aff.  rouaulti , C.  grandis , P.  cf. 
pulcher , P.  costai  and  A.  tejoensis  occur  further  south.  However,  in  the  lower  Llanvirn,  C.  cf.  thorali 
conjugens  appears  to  have  had  a wider  distribution  and  is  recorded  from  Moncorvo  and 
Bu<;aco  Rio  Ceira. 

Within  Brittany  and  Spain,  trilobite  associations  also  show  restricted  distribution  (Henry  1980u; 
Rabano  1984)  and  it  has  been  frequently  noted  that,  for  example,  sequences  and  faunas  in  the 
Crozon  Peninsula  have  more  in  common  with  the  Bugaco  area  in  Portugal  (Henry  and  Thadeu 
1971 ; Paris  1981 ; Young  1989,  1990)  than  with  the  Ordovician  succession  south  of  Rennes  (Henry 
and  Morzadec  1968;  Henry,  Melou  et  al.  1976;  Henry,  Nion  et  al.  1976). 

Two  maps  are  presented  (Text-fig.  4)  of  France  and  Iberia  during  early  Llanvirn  and  early 
Llandeilo  times  which  show  the  distribution  of  the  trilobites  described  in  this  paper.  These 
distributions  are  now  briefly  discussed. 

Early  Llanvirn.  C.  thorali  conjugens , S.  salteri  salteri  and  S.  sampelayoi  are  known  to  occur  in  the 
Montes  de  Toledo  and  Sierra  Morena  of  central  Spain.  Elsewhere  in  Iberia  and  Brittany  their 
presence  appears  to  be  patchy.  5.  salteri  salteri  possibly  occurs  in  the  Valongo-Arouca  region  while 
C.  cf.  thorali  conjugens  is  so  far  only  known  from  Bm;aco  and  Moncorvo  in  Portugal  and  probably 
a similar  form  is  present  in  the  Traveusot  Formation,  south  of  Rennes  in  Brittany  (J.-L.  Henry  pers. 
comm.).  S.  sampelayoi  (Hammann,  1977)  has  only  definitely  been  recorded  in  Spain  to  date. 

Early  Llandeilo.  As  in  the  lower  Llanvirn,  central  Spain  appears  to  have  been  environmentally 
homogeneous  in  that  C.  rouaulti , S.  salteri  salteri  and  P.  mendax  are  known  across  most  of  the 
region,  and  are  also  present  in  eastern  Portugal.  At  Valongo  C.  rouaulti  is  probably  absent  although, 
as  indicated  above,  a poorly  preserved  IColpocoryphe  may  belong  to  this  species.  In  the  Bugaco  area 
the  author  has  not  seen  specimens  of  either  S.  salteri  salteri  or  P.  mendax  although  Delgado  ( 1908) 
recorded  ‘ Calymene  pulchra'  from  the  Brejo  Fundeiro  Formation,  Louredo  Formation  and 
probably  Porto  de  Santa  Anna  Formation.  In  Brittany  all  three  species  are  known  from  the  median 
syncline,  Domfront  and  south  of  Rennes,  but  P.  mendax  does  not  occur  in  the  Crozon  Peninsula. 

The  distribution  of  the  above  species  is  informative  in  terms  of  environmental  differences  within 
the  Central  Iberian  Zone  ( sensu  Hammann  et  al.  1982)  and  Brittany.  During  early  Llanvirn  times 
all  the  areas  appear  to  show  a general  similarity  in  that  mud/silt  was  deposited  over  a broad  shelf 


336 


PALAEONTOLOGY, VOLUME  34 


text-fig.  4.  Maps  showing  distribution  of  trilobite  species  during  early  Llanvirn  and  early  Llandeilo  times  in 
Iberia  and  north-west  France.  Stippled  areas  represent  outcrop  of  Ordovician/Silurian  rocks. 


following  the  post  'Armorican  Quartzite  ’ transgression.  Little  direct  evidence  regarding  water  depth 
or  proximity  to  shore  can  be  ascertained  either  from  the  lithofacies  or  faunas,  and  one  of  the  few 
indications  that  there  was  a change  in  conditions  across  the  Iberian  region  is  seen  in  the  lower 
diversity  of  the  trilobite  faunas  from  south  to  north.  A similar  situation  probably  existed  during 
early  Llandeilo  times,  although  in  terms  of  the  species  considered  here  few  convincing  differences 
can  be  seen.  However,  when  consideration  is  given  to  a larger  sample  of  the  trilobite  faunas 
(Romano  1982),  as  well  as  to  the  lithofacies  (Brenchley  et  al.  1986)  the  differences  are  considerably 
more  marked.  The  major  contributing  factor  to  the  differences  in  the  trilobite  assemblages  is 
probably  water  depth,  with  its  accompanying  control  on  energy  level/light/temperature  and/or 
food  supply. 

It  was  suggested  by  Brenchley  et  al.  (1986)  that  the  Ordovician  shelf  in  central  and  western  Iberia 
deepened  towards  the  north  in  Llandeilo  times.  This  picture  fits  in  well  with  the  observed 
taphonomy  of  the  trilobite  assemblages  from  Valongo,  with  their  relatively  high  proportion  of 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


337 


complete  specimens  (Romano  1976)  and  frequent  dispersal  within  the  rock  (low  energy  conditions) 
compared  with  the  often  disarticulated  exoskeletons  and  common  bedding  plane  accumulations  at 
Bugaco  (higher  energy  conditions),  particularly  above  the  Monte  da  Sombadeira  Formation. 


SYSTEMATIC  PALAEONTOLOGY 

The  classification  of  Colpocoryphe  and  Salter ocoryphe  has  recently  been  comprehensively  discussed 
by  Henry  (19806)  and  Hammann  (1983).  Henry  pointed  out  reasons  for  excluding  the  former  from 
the  Homalonotidae  (Sdzuy  1957;  Bergstrom  1973;  Thomas  1977)  and  included  it,  with 
Salter  ocoryphe,  in  the  Calymenidae.  Henry  further  suggested  that  Salterocoryphe  could  be  placed 
in  the  Flexicalymeninae  (Siveter  1977),  supported  by  the  fact  that  Flexicalymene  ( Onnicalymene ) 
jemtlandica  and  Salterocoryphe  salteri  have  almost  identical  hypostoma,  and  that  Colpocoryphe 
should  be  restricted  to  Colpocoryphinae.  Hammann  (1983),  however,  favoured  the  inclusion  of 
both  Salterocoryphe  and  Colpocoryphe  within  the  Colpocoryphinae  of  the  Calymenidae  and 
considered  that  Prionocheilus  of  the  subfamily  Pharostomatinae  should  be  included  in  the 
Bathycheilidae. 

The  suprageneric  level  of  classification  is  not  further  discussed  here  and  in  the  following  section 
the  genera  are  not  grouped  into  higher  ranks. 


Genus  colpocoryphe  Novak  in  Perner,  1918 
Type  species.  Calymene  arago  Rouault,  1849. 


Colpocoryphe  aff.  rouaulti  Henry,  1970 
Plate  1,  figs  I -13,  15,  17 

?1908  Calymene  Aragoi  Rouault;  Delgado,  p.  57. 

1949  Synhomalonotus  Aragoi  (Rouault);  Thadeu,  pi.  1,  fig.  1. 

Material.  Two  cephala;  two  cranidia;  eight  pygidia,  with  or  without  attached  thoracic  segments;  thirteen 
complete,  or  nearly  complete  specimens;  all  preserved  as  internal  and/or  external  moulds. 

Horizon  and  locality.  SG  142  (Thadeu  1949,  p.  1,  fig.  1 ),  7143,  500  m N 40°  E of  Cacemes,  Bugaco.  SG  144, 
450  m S 70°  E of  Louredo,  Bugaco,  probably  Llanvirn.  SG  1326,  100  m N 40°  E of  Beloi  chapel,  probably 
Llanvirn.  SG  2190  and  MR  59-64,  section  from  Zuvinhal  to  Santa  Ant.  do  Cantaro,  unit  25,  Bugaco  (Delgado 
1908,  p.  35),  Llanvirn.  MR  41,  42,  section  through  Val.  San  Jorge,  unit  20,  Bugaco.  MR  43-48.  same  section 
as  specimens  41-42,  unit  21,  Bugaco  (Delgado  1908,  p.  42).  MR  49-51,  Palheiros,  Bugaco.  MR  52-58,  900  m S 
65°  E of  Venda  Nova,  Poiares.  The  material  occurs  in  beds  from  the  Brejo  Fundeiro  Formation  (Llanvirn)  to 
the  Fonte  da  Horta  Formation  (Llandeilo).  MR  41-48  are  of  Llandeilo  age,  MR  49-58  are  Llanvirn. 

Discussion.  The  material  is  certainly  very  close  to  C.  rouaulti  but  differs  from  it  in  several  respects. 
In  the  Portuguese  specimens  the  glabella  converges  forwards  more  markedly  and  the  straight 
anterior  margin  of  the  glabella  is  shorter.  The  swollen  posterior  lobe  to  the  central  body  of  the 
hypostoma  is  more  like  that  figured  by  Hammann  ( 1983)  while  the  internal  posterior  notch  is  closer 
to  that  of  Henry’s  (1970,  1980u,  b)  material.  The  pygidium  shows  slight  differences  in  the  shallower 
axial  and  vincular  furrows  and  smaller  side  lobes.  At  this  stage  the  author  prefers  to  identify  the 
Portuguese  material  as  C.  aff.  rouaulti.  Further,  the  Portuguese  material  suggests  that  there  may  be 
slight  differences  between  the  Llanvirn  and  Llandeilo  forms  assigned  here  to  C.  aff.  rouaulti. 
Although  the  cephala  are  virtually  indistinguishable  the  pygidial  axis  of  the  stratigraphically  lower 
specimens  tends  to  carry  less  well-defined  ring  furrows  and  the  vincular  furrows  are  less  strongly 
indented  than  in  the  Llandeilo  forms.  It  is  possible  that  the  Llanvirn  material  may  prove  to  be 
subspecifically  distinct  from  the  Llandeilo  form,  but  this  must  await  more  and  better  preserved 
material. 


338 


PALAEONTOLOGY,  VOLUME  34 


Colpocoryphe  cf.  thorali  conjugens  Hammann,  1983 

1986  Colpocoryphe  cf.  thorali  conjugens  Hammann;  Romano  et  al.,  p.  429,  pi.  1,  figs  2-5. 

1988  Colpocoryphe  cf.  thorali  conjugens  Hammann;  Rebelo  and  Romano,  p.  54,  pi.  I,  figs  8-11; 

pi.  2,  fig.  5. 

Material.  Four  cranidia;  two  cranidia,  with  part  thorax;  three  pygidia;  all  preserved  as  internal  and/or 
external  moulds. 

Horizon  and  locality.  PI  57/7,  L2  m above  lingulid  bed  at  top  of  Armorican  Quartzite  Formation,  road  section 
south  of  River  Mondego,  Penacova.  RC1/2,  10  cm  above  lingulid  bed  at  top  of  Armorican  Quartzite 
Formation,  track  section,  north  of  River  Ceira,  Vila  Nova  do  Ceira.  SG  1 154/1-4,  6,  10,  Xistenta  Formation, 
3-5  km  ESE  of  Mos.  13  km  east  of  Moncorvo.  P157/7  and  RC1/2  are  Lower  Llanvirn,  SG  1154/1^4,  6,  10, 
probably  Llanvirn. 

Discussion.  For  description  and  discussion  of  the  above  material  see  Romano  et  al.  (1986)  and 
Rebelo  and  Romano  (1988).  Nothing  new  can  be  added.  The  subspecies  is  known  from  lower 
Llanvirn  of  the  Sierra  Morena  (Hammann  1983;  Rabano  1984;  Gutierrez-Marco  et  al.  1984). 


Colpocoryphe  grandis  (Snajdr,  1956) 

Plate  2,  figs  1-3,  7,  8,  1 1 

? 1 908  Calymene  Aragoi  Rouault;  Delgado,  pp.  41,  57. 

*1956  Calymene  ( Colpocoryphe ) grandis  Snajdr;  p.  529,  pi.  3,  figs.  1-9. 

19806  Colpocoryphe  grandis  (Snajdr,  1956);  Henry,  text-fig.  3,  pi.  2,  figs  3 and  4. 

(for  full  synonymy  see  Flenry  1980a,  p.  64;  and  Hammann  1983,  p.  85). 

Material.  Three  cephala;  three  cranidia;  two  cephala,  with  part  of  thorax;  five  pygidia,  with  part  of  thorax; 
two  pygidia;  two  complete  or  nearly  complete  specimens;  all  preserved  as  internal  and/or  external  moulds. 

Horizon  and  locality.  LOR  1.007-9,  Louredo  Formation,  Favagal  Bed,  Louredo  village.  LOR  2.001,  less  than 
2 m below  Favagal  Bed,  Louredo  village.  PEN  1.001-2,  less  than  10  m below  Favagal  Bed,  quarry  320  m ENE 


EXPLANATION  OF  PLATE  1 

Figs  1-13.  15,  17.  Colpocoryphe  aft',  rouaulti  Henry,  1970.  1-3,  SG  142;  internal  mould  of  cephalon,  dorsal, 
anterior  and  lateral  views,  x 2,  Brejo  Fundeiro  Formation,  Bugaco,  Llanvirn.  4,  MR  41 ; internal  mould  of 
cranidium,  dorsal  view,  x F4,  Fonde  da  Horta  Formation,  Bugaco,  Llandeilo.  5,  MR  42;  internal  mould 
of  cranidium,  dorsal  view,  x 2,  Fonte  da  Horta  Formation,  Bugaco,  Llandeilo.  6-8,  MR  52;  internal  mould 
of  cranidium,  dorsal,  anterior  and  lateral  views,  x F8,  Brejo  Fundeiro  Formation,  Poiares,  Llanvirn.  9, 
MR  44;  internal  mould  of  cranidium,  dorsal  view,  x 1,  ?Fonte  da  Horta  Formation,  Bugaco,  Llandeilo.  10, 
SG  144;  internal  mould  of  pygidium,  dorsal  view,  x 2,  Brejo  Fundeiro  Formation,  Bugaco,  ?Llanvirn.  11, 

SG  ? 1 43 ; internal  mould  of  pygidium,  dorsal  view,  x 2,  Brejo  Fundeiro  Formation,  Bugaco,  ?Llanvirn.  12, 

MR  49;  internal  mould  of  pygidium,  dorsal  view,  x 2,  Brejo  Fundeiro  Formation,  Bugaco,  Llanvirn.  13, 

MR  53;  internal  mould  of  pygidium,  dorsal  view,  x2,  Brejo  Fundeiro  Formation,  Poaires,  Llanvirn.  15, 

MR  46;  internal  mould  of  nearly  complete  specimen,  dorsal  view,  x 1,  ?Fonte  da  Horta  Formation,  Bugaco, 
Llandeilo.  17,  MR  45;  internal  mould  of  nearly  complete  specimen,  x 1,  ?Fonte  da  Horta  Formation, 
Bugaco,  Llandeilo. 

Fig.  14.  Colpocoryphe  sp.  MD  2.001/2;  internal  mould  of  incomplete  cranidium,  dorsal  view,  x 6,  Carregueira 
Formation,  Domes,  Caradoc. 

Fig.  16.  Colpocoryphe ? sp.  indet.  SG  146;  partly  enrolled  specimen  with  6 thoracic  segments  and  pygidium, 
dorsal  view  of  pygidium,  x 1.2,  Fonte  da  Horta  Formation,  Bugaco,  Llandeilo. 

Fig.  18.  Salterocoryphe  salteri  salteri  (Rouault,  1851).  SG  1 681 ; internal  mould  of  pygidium,  dorsal  view,  x 09, 
Valongo  Formation,  Valongo,  Llandeilo. 


PLATE  1 


ROMANO,  Colpocoryphe , Colpocoryphel,  Salter ocoryphe 


340 


PALAEONTOLOGY, VOLUME  34 


of  east  end  of  bridge  over  River  Mondego,  east  of  Penacova.  QXP  2.001-5,  40,  and  Magao  specimen  of  Cooper 
(1980),  ‘1700  mN  57°  E de  pyr.  de  Queixoperra,  Magao',  probably  from  'Bryozoa  Beds’  (Cooper  1980; 
Romano  1982)  within  unit  7 of  the  ‘Schistes  a Orthis  Berthoisi'  (Delgado  1908,  p.  92),  Queixoperra  Member 
of  Cabego  do  Peao  Formation.  CST  2.001M,  1400  mN  62°  E of  Pereiro,  Magao,  oolitic  beds  probably 
equivalent  to  basal  oolite  (Favagal  Bed)  of  Louredo  Formation.  ABO  9.001,  Aboboreira,  Carregueira 
Formation,  from  less  than  3m  below  oolitic  beds,  and  ABO  10.001,  basal  ‘Bryozoa  Beds’,  Queixoperra 
Member,  both  approximately  1 km  WNW  of  Carregueira,  Magao.  T.  Young  collection,  unnumbered 
specimens  from  2 km  SSE  of  Aboboreira  [20710,  28915],  and  west  of  Pereiro  [20975,  29090];  all  from  Favagal 
Bed.  Domes  material  (loc.  70),  grid  reference  18992  31368,  from  ‘Bryozoa  Beds’  of  Cabego  do  Peao 
Formation.  Fragmental  material  is  also  known  from  near  the  top  of  the  Carregueira  Formation  at  Rio  Ceira 
(Young  1985).  All  specimens  are  probably  of  early  Caradoc  age. 

Discussion.  The  present  material  agrees  in  all  important  respects  with  that  described  and  figured  by 
Snajdr  (1956),  Destombes  (1966),  Henry  (1980a)  and  Hammann  (1983). 


Colpocoryphe  ? sp.  indet. 

Plate  1,  fig.  16 

71908  Calymene  transiens  Verneuil  and  Barrande;  Delgado,  p.  57. 

1949  Synhomalonotus  transiens  (Verneuil  and  Barrande);  Thadeu,  pi.  1,  fig.  6. 

Material.  SG146.  Internal  mould  of  enrolled  specimen  with  six  thoracic  segments  and  pygidium  (Thadeu  1949, 
pi.  1,  fig.  6). 

Horizon  and  locality.  ‘ 100  m S 80°  E of  Foredo’,  Bugaco.  Delgado  (1908,  p.  57)  records  the  species  from  the 
‘Schistes  a Homalonotus  oehlerti'  (Fonte  da  Horta  Formation)  of  Flandeilo  age. 

Description.  Thoracic  segments  of  Colpocoryphe  type  (see  Henry  1980a,  pi.  7,  fig.  la)  carrying  sculpture  of  small 
tubercles.  Pygidial  axis  wide  anteriorly,  narrowing  evenly  backwards  and  with  shallow  axial  furrows,  posterior 
part  not  preserved.  Eight  visible  axial  rings  seen  separated  by  shallow,  complete  ring  furrows.  Small  triangular 
pleural  lobes  extend  back  to  eighth  axial  ring  and  carry  up  to  four  poorly  defined  ribs.  Fateral  borders  have 
wide,  open  furrows  with  no  trace  of  segmentation  on  lower  surfaces.  Sculpture  slightly  coarser  than  on  thorax. 

Discussion.  The  absence  of  segmentation  on  the  lateral  borders  is  typical  of  the  genus  Colpocoryphe 
as  distinct  from  Salterocorvphe.  The  ribs  on  the  pleural  lobes  are  more  obvious  than  in  C.  rouaulti 
and  C.  grandis  and  there  is  no  median  shallowing  of  the  axial  ring  furrows  in  the  pygidium  as  in 
the  latter  species,  although  this  feature  is  more  apparent  on  external  moulds  (Henry  1980a,  pi.  7, 
figs  6a,  b and  7;  pi.  8,  fig.  2 a-d). 


EXPLANATION  OF  PLATE  2 

Figs  1-3,  7,  8,  11.  Colpocoryphe  grandis  (Snajdr,  1956).  1.  QXP  2.0001;  internal  mould  of  incomplete 
cranidium,  dorsal  view,  x 1,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  2,  7,  QXP  2.040; 
internal  mould  of  pygidium,  dorsal  and  posterior  views,  x 1 and  x 1-4  respectively,  Cabego  do  Peao 
Formation,  Amendoa/Magao,  Caradoc.  3,  PEN  1.002;  internal  mould  of  pygidium,  dorsal  view,  x 1, 
Carregueira  Formation,  Amendoa/Magao,  Caradoc.  8,  CST  2.004;  internal  mould  of  cephalon,  anterior 
view,  xO-6,  Favagal  Bed,  Magao,  Caradoc.  11.  CST  2.003;  internal  mould  of  fragmentary  cephalon  and 
hypostoma,  anterior  view,  x 0-7,  Favagal  Bed,  Magao,  Caradoc. 

Figs  4-6,  9,  10,  12.  Salterocoryphe  salteri  salteri  (Rouault,  1851).  4,  SG  1687.1 ; internal  mould  of  incomplete 
specimen,  dorsal  view,  x 1,  Valongo  Formation,  Valongo,  Flandeilo.  5,  SG  149;  internal  mould  of  complete 
specimen,  dorsal  view,  x 1-3,  Valongo  Formation,  Valongo,  Flandeilo.  6,  SG  1686.1;  internal  mould  of 
partly  enrolled  specimen,  dorsal  view,  x 1-2,  Valongo  Formation,  Valongo,  Flandeilo.  9,  SG  1325;  internal 
mould  of  specimen  with  hypostoma,  dorsal  view,  x 1-4,  Valongo  Formation,  Valongo,  Flandeilo.  10,  12, 
SG  1687;  internal  mould  of  nearly  complete  specimen,  dorsal  view,  x 1,  anterior  view,  x 14,  respectively, 
Valongo  Formation,  Valongo,  Flandeilo. 


PLATE 


ROMANO,  Colpocoryphe,  Salter ocoryphe 


342 


PALAEONTOLOGY, VOLUME  34 


The  incomplete  specimen  precludes  specific  identification.  Delgado  and  Thadeu  referred  the 
species  to  ‘ Calymene  transiens ’ (Verneuil  and  Barrande  1855,  p.  974,  pi.  25,  fig.  5)  from  Almaden, 
Spain,  but  Verneuil  and  Barrande’s  figure  and  description  do  not  permit  a close  comparison. 
Tromelin  and  Lebesconte  (1876,  p.  629)  reinvestigated  the  type  of  transiens  and  regarded  it  as 
belonging  to  ‘ Calymene  salteri \ Henry  (1970,  p.  22)  pointed  out  that  Salteroeoryphe  salteri  is 
present  at  Almaden  which  tends  to  support  Tromelin  and  Lebesconte’s  suggestion. 

Hammann  (1983,  p 90)  reported  that  the  type  of  Calymene  transiens  could  not  be  found  and  that 
the  species  cannot  reliably  be  attributed  to  either  Colpocoryplie  or  Salteroeoryphe.  However, 
Hammann  considered  it  to  be  closer  to  the  latter. 


Colpocoryplie  sp. 

Plate  1,  fig.  14 

Material.  MDC  2.001/2,  part  and  counterpart  of  incomplete  cranidium. 

Horizon  and  locality.  Carregueira  Formation,  Domes,  type  section  (Young  1985),  about  5 m below  oolitic 
horizon  (at  base  of  Cabego  do  Peao  Formation).  Lower  Caradoc. 

Description.  Glabella  (excluding  occipital  ring)  slightly  longer  than  wide,  sides  gently  converging  anteriorly. 
Occipital  furrow  forwardly  flexed,  occipital  ring  carries  small  median  tubercle  which  is  considerably  fainter  on 
external  mould.  Anterior  margin  of  glabella  gently  rounded  with  short,  straight  median  part.  S2  furrows  are 
short,  straight  and  inclined  only  slightly  backwards;  S3  very  short  and  indistinct.  Anterior  notch  of  cranidium 
is  broad  with  widely  diverging  sides.  Cranidium  is  finely  tuberculate. 

Discussion.  The  specimen  is  small  (about  4-5  mm  long)  and  may  represent  a meraspid  stage.  The 
open  anterior  notch  suggests  affinities  with  Colpocoryplie  grandis  but  this  species  does  not  possess 
such  a narrow  glabella,  at  least  in  adult  specimens,  or  a median  occipital  tubercle.  The  short  S2  and 
S3  furrows  and  fine  sculpture  are  features  of  Salteroeoryphe  salteri  salteri  (Hammann  1977;  Henry 
1980u)  and  the  juvenile  of  this  species  bears  a median  occipital  tubercle  (Hamman  1983,  pi.  1 1,  fig. 
110).  However  the  structure  of  the  anterior  cephalic  border  is  typical  of  Colpocoryplie  and  until 
juvenile  specimens  of  C.  grandis  are  described  it  is  preferable  to  leave  the  Portuguese  specimen  in 
open  nomenclature. 


Genus  salterocoryphe  Hamman,  1977 
Type  species.  Calymene  salteri  Rouault,  1851. 


Salterocoryphe  salteri  salteri  (Rouault,  1851) 

Plate  1,  fig.  18;  Plate  2,  figs  4-6,  9,  10,  12;  Plate  3,  fig.  9. 

*1851  Calymene  salteri  Rouault,  p.  358. 

1949  Synhomalonotus  salteri  (Rouault)  Thadeu,  pi.  1,  figs  2-3. 

1949  Synhomalonotus  lusitanica  Delgado;  Thadeu,  p.  131,  pi.  1,  figs  7-9;  pi.  2,  figs  1 and  2. 

1960  Neseuretus  lusitanica  (Thadeu);  Whittard,  p.  145. 

1966  Colpocoryplie  lusitanica  (Thadeu);  Dean,  p.  309. 

1982  Neseuretus  lusitanicus  (Thadeu);  Fortey  and  Morris,  p.  70. 

1982  Salterocoryphe  lusitanica  Romano,  p.  96. 

1982  Salterocoryphe  salteri  Romano  in  Hammann,  Robardet  and  Romano,  p.  40. 

(for  full  synonymy  see  Henry  1970,  p.  18;  and  Hammann  1983,  p.  90). 

Material.  Five  complete  or  nearly  complete  specimens;  fourteen  other  specimens;  all  preserved  as  internal  or 
external  moulds. 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


343 


Horizon  and  locality.  SG  147  (figured  by  Thadeu  1949,  pi.  2,  fig.  2),  ‘ vizinhangas  de  Valongo'.  SG  148  (Thadeu 
1949,  pi.  1,  fig.  9),  ‘800  m NE  de  Boloi’.  SG  149  and  150  (Thadeu  1949,  pi.  1,  figs  7 and  8),  ‘ Ribeira  da 
Murta,  Valongo’.  SG  1688,  (Thadeu  1949,  pi.  2,  fig.  1)  ‘ 1650  m (non  1680  m,  Thadeu  1949,  p.  131 ) S 20°  W 
da  piramide  de  Santa  Justa’.  SG  1323  and  1324,  ‘ 1000  m S 30°  E da  igreja  de  Covelo,  Valongo’.  Information 
taken  from  labels  on  specimens,  slightly  modified  using  Thadeu  (1949).  Other  specimens  from  Beloi,  Covelo, 
Santa  Justa  and  Penha  Garcia  (see  Text-fig.  1).  PG  6.001  from  approximately  11m  above  Monte  da 
Sonrbadeira  Formation,  Penha  Garcia.  All  north  Portuguese  material  is  probably  from  upper  part  of  the 
Valongo  Formation  (Schistes  a Uralichas  Ribeiroi  of  Delgado  1908)  of  Llandeilo  age. 

Discussion.  The  species  has  been  recently  described  and  figured  by  Henry  (1970)  and  Hammann 
(1983).  Henry  (1980u)  distinguished  two  subspecies  of  S.  salteri  of  which  the  Portuguese  material 
may  be  assigned  to  5.  salteri  salteri. 

Since  Thadeu  (1949)  first  described  Salter ocoryphe  lusitanica , various  authors  (Whittard  1960; 
Dean  1966)  have  briefly  referred  to  it  in  discussions  relating  to  generic  assignment.  Henry  (1970, 
p.  21)  discussed  the  status  of  the  species  when  he  suggested  that  it  bore  a striking  resemblance  to 
S.  salteri  in  that  the  form  of  the  glabella,  eye  position  and  number  of  axial  rings  were  identical.  The 
only  difference  that  Henry  noted  was  that  the  pleural  lobes  on  the  pygidium  were  more  clearly 
segmented  in  the  Portuguese  material,  but  this  he  thought  could  well  be  the  result  of  deformation. 
A study  of  additional  material  indeed  confirms  Henry’s  suggestion  that  the  preservation  of  the 
furrows  varies  with  the  deformation.  The  anterior  part  of  the  pygidial  axis  tends  to  be  relatively 
narrower  in  the  Portuguese  specimens  but  this  does  not  seem  to  be  an  important  criterion  for 
separating  the  two  forms.  Hence  I prefer  to  put  lusitanica  into  synonymy  with  salteri.  Hammann 
(1983,  p.  93)  regarded  lusitanica  as  a distinct  species  but  his  criteria  are  not  accepted  here;  for 
example  the  range  in  glabella  length : width  ratios  of  salteri  and  lusitanica  are  virtually  identical  and 
the  ornament  of  specimens  assigned  to  lusitanica  is  similar  to  that  of  salteri. 


Genus  prionocheilus  Rouault,  1847 
(Syn.  Pharostoma  Hawle  and  Corda,  1847) 

Type  species.  Prionocheilus  verneuili  Rouault,  1847. 

Remarks.  The  question  of  the  priority  of  Prionocheilus  Rouault,  1847  or  Pharostoma  Hawle  and  Corda,  1847 
has  been  discussed  by  Dean  (1964,  1966,  p.  300;  1971,  p.  42),  Whittington  (1965,  p.  56),  Ingham  (1977,  p.  103), 
Siveter  (1977,  pp.  339,  393),  Owen  and  Bruton  (1980,  p.  2),  Henry  ( 1980n,  p.  79)  and  Hammann  ( 1983,  p.  51 ). 
For  the  present  paper  I prefer  to  accept  Dean’s  argument  and  follow  his  suggestion  for  using  Prionocheilus. 


Prionocheilus  mendax  (Vanek,  1965) 

Plate  3,  figs  1-5,  8 

1908  Calymene  pulchra  Barrande;  Delgado,  pp.  106,  134,  7138. 

1942  Calymene  pulchra  Barrande;  Costa,  p.  93. 

1949  Calymene  pulchra  Barrande;  Thadeu.  p.  129,  pi.  2,  figs  3-5. 

*1965  Pharostoma  pulchrum  mendax ; Vanek,  pp.  30—32,  fig.  6;  pi.  2,  fig.  10;  pi.  3,  figs  6 and  7;  pi.  4, 
figs  2-5. 

(for  a full  synonymy  see  Vanek  1965,  p.  30;  Henry  1980n,  pp.  80-81;  and  Hammann  1983,  p.  53). 

Material.  Three  cephala  with  part  thorax;  one  hypostoma;  two  free  cheeks;  twenty-three  complete  or  nearly 
complete  specimens;  all  preserved  as  internal  and/or  external  moulds. 

Horizon  and  locality.  SG  151,  ‘Valongo’.  SG  1692,  1692.1-3,  1693.1  and  MR  38-40,  1400  m S 32°  E of  Covelo 
church,  Valongo.  SG  1327,  1327.1,  1000  nr  S 30°  E of  Covelo  church,  Valongo.  SG  1691,  1691.1-3,  800  m S 
26°  W of  ‘ermida  de  Santa  Justa,  Valongo’.  Delgado  (1908)  records  the  species  from  the  ‘Schistes  a 
Didymograptus'  (Llanvirn)  to  the  ‘Schistes  a Uralichas  Ribeiroi ’ (Llandeilo)  of  the  Valongo  Formation 


344 


PALAEONTOLOGY, VOLUME  34 


(Romano  and  Diggens  1976;  it  is  not  possible  to  relate  his  specimens  to  exact  horizons.  The  author  has 
collected  this  species  from  beds  of  Llandeilo  age  at  Valongo  but  has  not  recorded  it  from  the  Llanvirn. 

Description.  A full  description  is  not  given  since  the  species  is  well  documented.  Cephalon  semicircular  in 
outline  with  evenly  rounded  anterior  and  lateral  margins.  Glabella  subtriangular  in  outline,  with  evenly  curved 
anterior  margin  and  slightly  curved  sides.  Maximum  width  of  cephalon  about  two  and  a half  times  that  of 
posterior  glabellar  width.  Glabella  from  0.7-0. 8 times  as  long  as  cephalon.  Three  pairs  of  glabellar  lobes  and 
furrows.  Faint  oval  areas  situated  on  inner  side  of  posterior  branch  of  IS.  Glabella  gently  convex  dorsally. 
Axial  furrows  generally  deep,  expanding  into  small,  crescent-shaped  paraglabellar  areas  abaxial  to  1L. 
Palpebral  lobes  prominent,  situated  opposite  2L  and  nearer  to  axial  furrow  than  lateral  margin.  Faint  eye  ridge 
runs  to  2S.  Free  cheeks  with  long,  posteriorly  directed  genal  spines.  Lateral  and  anterior  margin  of  cephalon 
carry  at  least  fifty  downwardly  directed,  slightly  curved  (posteriorly)  spines.  Sculpture  of  small  tubercles  of 
uniform  size,  absent  in  paraglabellar  areas. 

Hypostoma  consists  of  gently  convex,  subovate  middle  body,  longer  than  wide,  with  shallow  inwardly 
directed  furrows  defining  a posterior  crescent-shaped  lobe;  lobe  consists  of  two  oblique  lateral  lobes. 
Anterolateral  margins  with  small  outwardly  directed  pointed  wings.  Posterior  margin  of  hypostoma  has  a 
shallow  open  notch;  posterior  projections  are  rounded. 

Thorax  consists  of  thirteen  segments.  Axial  furrows  gently  outwardly  curved ; axis  widest  at  about  third  axial 
ring  where  it  is  over  one  and  a half  times  as  wide  as  at  posterior  end.  Axial  rings  lobate  laterally.  Broad  (trans.), 
horizontal  inner  parts  of  pleural  region,  outer  parts  bent  sharply  down.  Pleural  furrows  deep,  wide  (exsag.)  and 
straight,  starting  at  anterolateral  corner  of  axial  ring  and  running  approximately  parallel  to  pleural  margins. 
Posterior  border  slightly  wider  (exsag.)  than  anterior.  At  geniculation,  furrows  swing  forwards  and  die  out 
before  reaching  rounded  tip  of  segment.  Thorax  finely  tuberculate  like  cephalon. 

Pygidium  semicircular  in  outline.  Anterior  end  of  axis  about  one-third  maximum  width  of  pygidium.  Axis 
narrows  evenly  backwards,  not  reaching  posterior  margin.  Axis  carries  five  rings  (sometimes  with  faint 
suggestion  of  a sixth)  and  a semicircular  terminal  piece  which  stands  higher  than  rest  of  axis.  Ring  furrows 
shallow  and  narrow  (sag.)  posteriorly.  Up  to  five  nearly  straight  ribs,  separated  by  deep  furrows  which  curve 
strongly  backwards  distally.  First,  three/four  ribs  carry  short  furrows  extending  from  axial  furrow.  Sculpture 
similar  to  that  of  cephalon  and  thorax. 


EXPLANATION  OF  PLATE  3 

Figs  1-5,  8.  Prionocheilus  mendax  (Vanek,  1965).  1,  MR  38.3  and  38.5;  latex  cast  of  external  mould,  dorsal 
view,  x 1,  Valongo  Formation,  Valongo.  Llandeilo.  2,  MR  38.6-8;  latex  cast  of  external  mould,  dorsal  view, 
x08,  Valongo  Formation,  Valongo,  Llandeilo.  3,  MR  39;  internal  mould  of  incomplete  specimen,  dorsal 
view,  x 1,  Valongo  Formation,  Valongo,  Llandeilo.  4,  MR  38.1 ; latex  cast  of  external  mould,  dorsal  view, 
x 1,  Valongo  Formation,  Valongo,  Llandeilo.  5,  SG  1692.1;  latex  cast  of  internal  mould  showing 
hypostoma,  dorsal  view,  x 1,  Valongo  Formation,  Valongo,  Llandeilo.  8,  MR  38.13;  latex  cast  of  external 
mould  of  free  cheek,  dorsal  view,  x 1,  Valongo  Formation,  Valongo,  Llandeilo. 

Figs  6,  10.  12,  13.  Prionocheilus  cf.  pulcher  (Barrande,  1846).  6,  QXP  2.017;  latex  cast  of  external  mould  of 
cranidium,  dorsal  view,  x 3,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  10,  SG  152;  internal 
mould  of  cranidium,  dorsal  view,  x 1-5,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  12, 
QXP  2.014;  internal  mould  of  cranidium,  dorsal  view,  x 2,  Cabego  do  Peao  Formation,  Amendoa/Magao, 
Caradoc.  13,  QXP  2.009;  latex  cast  of  external  mould  of  pygidium,  dorsal  view,  x 2,  Cabego  do  Peao 
Formation,  Amendoa/Magao.  Caradoc. 

Fig.  9.  Salterocoryphe  salteri  salteri  (Rouault,  1851).  PC  6.001;  latex  cast  of  external  mould  of  cranidium, 
dorsal  view,  x F75,  Fonte  da  Florta  Formation,  Penha  Garcia,  Llandeilo. 

Figs  7,  1 1,  14-16.  Actinopeltis  tejoensis  sp.  nov.  7,  QXP  2.041 ; internal  mould  of  pygidium,  dorsal  view,  x 2, 
Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  II,  QXP  2.043;  internal  mould  of  incomplete 
pygidium,  dorsal  view,  x 3,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  14,  QXP  2.006; 
internal  mould  of  cephalon,  dorsal  view,  x 2,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc.  15 
and  16,  SG  225  (holotype);  internal  mould  and  latex  cast  of  corresponding  external  mould,  dorsal  views, 
x 1-4  and  F8  respectively,  Cabego  do  Peao  Formation,  Amendoa/Magao,  Caradoc. 


PLATE  3 


ROMANO,  Prionocheilus,  Salter ocoryphe,  Actinopeltis 


346 


PALAEONTOLOGY, VOLUME  34 


Discussion.  The  Portuguese  material  is  very  similar  to  that  figured  by  Vanek  (1965)  from  the 
Dobrotiva  Formation  (Llandeilo)  to  Letna  Formation  (lower  Caradoc)  of  Bohemia.  A minor 
difference  is  the  shallower  posterior  axial  ring  furrows  and  pleural  furrows.  This  was  also  noted  by 
Flenry  (1980«,  p.  81)  who  recorded  the  species  from  the  upper  part  of  the  Traveusot  and  Andouille 
formations  (Llandeilo)  of  Brittany.  Flenry  (1980a)  figured  an  in  situ  hypostoma  and  commented  on 
the  difference  between  it  and  that  figured  by  Vanek  (1965,  pi.  2,  fig.  10).  Vanek’s  specimen  of  a 
hypostoma  is  incomplete  and  contrasts  with  the  notched  posterior  margin  of  specimens  from 
Brittany  (Henry  1980a,  fig.  31,  pi.  14,  fig.  3 a)  and  Spain  (Hammann  1983,  text-fig.  14).  Although 
the  two  Portuguese  in  situ  hypostomata  are  not  well-preserved,  they  both  show  the  notched 
posterior  margin;  the  posterior  projections,  however,  have  more  rounded  outlines  than  in  the 
Brittany  specimen.  The  minor  differences  mentioned  above  are  considered  insufficient  to  separate 
the  Portuguese  species  from  Prionocheilus  mendax. 

Prionocheilus  cf.  pulcher  (Barrande,  1846) 

Plate  3,  figs  6,  10,  12,  13 

1908  Calymene  pulchra  Barrande;  Delgado,  pp.  57,  80. 

Material.  Thirteen  cranidia;  one  free  cheek;  two  cephala  with  part  of  thorax;  four  pygidia;  all  preserved  as 
internal  and/or  external  moulds. 

Horizon  and  locality.  SG  152,  ‘Aboboreira,  300  m N 60°  W (Maqao)’,  from  the  'Schistes  a Orthis  ( = 
Svobodaina)  Berthoisi  ’ (Delgado  1908,  p.  80,  but  not  listed  in  following  descriptions  of  stratigraphic  sections). 
QXP.  2.008-2.028,  ‘ 1700  m N 57°  E de  pyr.  de  Queixoperra’,  Maqao;  ‘Bryozoa  Beds’,  Queixoperra  Member, 
‘Schistes  a Orthis  Berthoisi'.  ABO  10.002,  approximately  1 km  WNW  of  Carregueira,  Maqao;  basal  ‘Bryozoa 
Beds’,  Queixoperra  Member,  Cabeqo  do  Peao  Formation.  All  material  of  Caradoc  age  (probably  early). 

Description.  Glabella  subtriangular  in  outline  with  nearly  straight  anterior  margin,  length  just  over  three- 
quarters  the  basal  width.  Glabella  nearly  two-thirds  as  long  as  cranidium.  Occipital  ring  about  same  length  as 
anterior  border  medially.  Behind  LI,  occipital  ring  is  constricted  and  swings  forwards  where  at  posterolateral 
corner  of  LI  it  is  half  of  its  median  length.  Occipital  furrow  shallow  and  straight  behind  central  glabellar  lobe; 
at  inner  posterior  corner  of  LI  furrow  deepens  and  remains  so  to  axial  furrow.  Three  pairs  of  unequal  glabellar 
lobes.  LI  largest,  length  just  under  half  that  of  glabella,  with  nearly  straight  lateral  and  posterior  margin,  and 
angular  anterolaterally.  SI  shallow  near  axial  furrow,  deepest  at  inner  anterior  corner  of  LI  where  furrow 
bifurcates.  Posterior  branch  runs  backwards  and  curves  inwards;  anterior  branch  shallow  and  short,  directed 
inwards  and  forwards.  L2  just  over  half  the  length  of  LI,  with  more  or  less  straight  anterior  and  posterior 
margins.  S2  straight,  shallow  near  axial  furrow,  directed  inwards  and  backwards  at  a smaller  angle  to  the 
midline  than  SI.  LI  and  L2  separated  from  central  glabellar  lobe  by  very  faint  furrow.  L3  very  small  and 
delimited  anteriorly  by  very  faint  S3.  Oval  areas  situated  adaxial  to  posterior  branch  of  SI.  Glabella  gently 
convex  (trans.  and  sag.).  Axial  furrow  gently  curved,  convex  outwards,  shallowest  opposite  L2  and  at  posterior 
end  of  LI . Outside  LI , axial  furrow  expanded  into  crescent-shaped  paraglabellar  areas.  Anterior  pit  associated 
with  slightly  inwardly  placed  large  tubercle  situated  on  outer  side  of  axial  furrow,  just  anterior  to  S3. 
Preglabellar  field  separated  from  glabella  by  narrow,  shallow  furrow;  preglabellar  field  of  same  length  as 
anterior  border  and  slopes  gently  backwards.  Prominent,  convex  (sag.)  anterior  border  separated  from 
preglabellar  field  by  well  marked  furrow  which  shallows  abaxially.  Posterior  border  narrow  (exsag.)  at  axial 
furrow,  widening  abaxially.  Back  of  palpebral  lobe  level  with  where  SI  meets  axial  furrow,  anterior  margin  of 
palpebral  lobe  approximately  level  with  anterior  corner  of  L2.  Palpebral  lobe  slopes  inwards  and  merges  with 
fixed  cheek.  Faint  eye  ridge  running  inwards  and  forwards  from  palpebral  lobe  to  meet  axial  furrow  just  behind 
anterior  pit.  Anterior  branch  of  facial  suture  runs  in  slightly  sigmoidal  curve  to  cut  anterior  margin  in-line 
approximately  with  outer  part  of  paraglabellar  areas  (preservation  poor).  Posterior  branch  of  facial  suture  runs 
outwards  and  backwards  (posterolateral  parts  of  fixed  cheeks  not  preserved).  Free  cheek  narrow,  extending 
into  long,  posteriorly  directed  genal  spine  reaching  back  to  at  least  6th  thoracic  segment.  At  least  nineteen 
ventrally  directed  and  slightly  curved  spines  (just  under  0 5 mm  long)  situated  along  border.  Sculpture  on 
cephalon  of  fine  tubercles,  about  twenty  per  square  mm;  absent  in  furrows  and  very  sparse  on  preglabellar  field. 

Hypostoma  not  known.  Thorax  of  Prionocheilus  type,  tuberculate  except  in  furrows.  Pygidium  strongly 
curved  anteriorly,  gently  curved  posterior  margin.  Pygidium  two  and  a half  times  as  wide  as  anterior  part  of 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


347 


axis;  latter  narrows  evenly  posteriorly  and  about  four-fifths  length  of  pygidium.  Seven  axial  rings  narrowing 
(sag.)  posteriorly,  6th  and  7th  axial  ring  furrows  weak  to  absent  medianly.  Terminal  piece  about  one-quarter 
axial  length,  broadly  rounded  and  sloping  down  steeply  posteriorly.  Six  pairs  of  ribs  separated  by  deep  furrow 
which  terminate  just  before  lateral  margins.  Surface  of  pygidium  tuberculate. 

Discussion.  In  most  features  the  Maqao  specimens  are  very  close  to  Prionocheilus  pulcher  (Barrande 
1852,  pi.  19,  figs  1-3,  6;  see  also  Vanek  1965,  p.  31,  pi.  3,  figs  3-5,  pi.  4,  fig.  1,  text-fig.  5).  Minor 
differences  include  the  straighter  anterior  border  in  the  Portuguese  specimens  and  the  less  dense 
ornament,  particularly  on  the  fixed  cheeks  (cf.  Vanek  1965,  pi.  3,  fig.  4).  P.  pulcher  is  known  from 
the  Vinice,  Zahorany  and  Bohdalec  Formations  of  Bohemia  (Havlicek  and  Vanek  1966)  but  is  only 
tentatively  recorded  from  NW  France  (Henry  1980a,  p.  187)  where,  however,  the  very  similar 
P.  verneuili  Rouault  is  known  from  beds  of  Caradoc  age  to  the  south  of  Rennes  (Riadan  Formation) 
and  possibly  in  the  Crozon  Peninsula  (top  of  Postolonnec  Formation)  (Henry  1980a,  p.  80).  Henry 
stated,  as  Dean  (1966,  p.  303)  had  noticed,  that  the  deformation  of  the  Riadan  specimens  made 
some  of  the  distinguishing  features  less  certain;  thus  the  status  of  verneuili  is  still  in  doubt. 


Prionocheilus  costai  (Thadeu,  1947) 

Plate  4,  figs  1-9 

1908  Calymene  Costai  Delgado,  p.  57. 

*1947  Pharostoma  Costai  (Delgado);  Thadeu,  p.  218,  pi.  2,  figs  5-10. 

1949  Pharostoma  Costai  (Delgado);  Thadeu,  p.  130. 

1960  Pharostoma  Costai  (Delgado);  Whittard,  p.  138. 

1976  Prionocheilus  costai  (Delgado);  Hammann,  p.  39,  pi.  4,  figs  46-51 ; pi.  5,  figs  52-58;  text-fig.  7. 
1980a  Prionocheilus  costai  (Delgado);  Henry,  p.  80. 

1982  Prionocheilus  costai ; Hammann  et  a/.,  p.  23. 

1983  Prionocheilus  costai  (Delgado  1908);  Hammann,  p.  55,  pi.  3,  figs  34—36. 

1984  Prionocheilus  costai  (Delgado);  Rabano,  p.  272. 

Material.  Designated  lectotype:  SG  160  (Thadeu  1947,  pi.  2,  fig.  8).  Paralectotypes ; SG  161-163  (Thadeu  1947, 
pi.  2,  figs  7,  5 and  6 respectively).  Three  cephala  with  part  of  thorax;  two  nearly  complete  specimens;  all 
preserved  as  internal  and/or  external  moulds. 

Horizon  and  locality.  All  specimens  are  listed  by  Delgado  (1908)  as  occurring  in  the  'Schistes  culminants  et 
schistes  diabasiques',  250-300  m N 40°  W of  Louredo.  Porto  de  Santa  Anna  Formation,  late  Caradoc- Ashgill 
age.  The  specimens  are  probably  from  the  lower  part  of  the  unit,  the  Leira  Ma  Member. 

Description.  Since  the  species  has  already  been  described  by  Thadeu  (1947)  and  a further  full  account  was  given 
by  Hammann  (1976),  only  additional  notes  will  be  given  here. 

Thadeu  noted  that  only  two  pairs  of  glabellar  furrows  are  present.  However,  on  specimens  SG  160  and  161, 
short,  shallow  inwardly  directed  S3  start  level  from  where  the  eye  ridge  meets  the  axial  furrow.  The  L3  thus 
defined  are  very  short  (exsag.)  and  less  than  half  the  length  of  L2.  Over  sixty  downwardly  directed  short  spines 
are  present  on  the  convex  cephalic  doublure  and  are  continuous  around  the  anterior  margin  of  the  cephalon. 
The  axial  rings  and  posterior  and  anterior  bands  on  the  pleurae  carry  numerous  large  tubercles.  On  specimen 
SG  162  these  tubercles  are  seen  to  form  the  bases  of  short  posterodorsally  directed  spines  up  to  0-5  mm  in 
length.  The  pygidium  is  nearly  three  times  as  wide  as  long.  The  axis  consists  of  five  rings  and  a terminal  piece, 
and  four  (five)  backwardly  directed  pleural  furrows  with  less  distinct  interpleural  furrows. 

Discussion.  Delgado  first  used  the  specific  name  costai  in  a faunal  list  (1908,  p.  57).  Although  he  did 
not  describe  or  figure  the  species,  later  authors  (see  synonymy  above)  have  credited  it  to  Delgado, 
following  the  practice  of  Thadeu  (1947)  who  was  the  first  to  formally  describe  the  species.  In  this 
work  authorship  is  attributed  to  Thadeu. 

All  the  differences  between  P.  costai  and  P.  pulcher  (Barrande)  (authorship  attributed  to  Beyrich 
by  Whittard  1960,  p.  134)  listed  by  Whittard  (1960,  p.  138)  are  now  known  not  to  be  valid.  Thus 
P.  costai  does  possess  a spinose  cephalic  border  and  preglabellar  field  (although  in  Hammann  1976, 


348 


PALAEONTOLOGY, VOLUME  34 


text-fig.  7 the  spines  do  not  appear  to  be  continuous  around  the  anterior  margin).  Also  the  glabella 
has  straighter  sides  in  the  Iberian  species,  there  are  fewer  pygidial  ribs  and  the  granular  sculpture 
is  coarser. 


Genus  actinopeltis  Hawle  and  Corda,  1847 
Type  species.  Actinopeltis  globosa  (Barrande,  1852). 


Actinopeltis  tejoensis  sp.  nov. 

Plate  3,  figs  7,  1 1,  14—16;  Text-fig.  5 
1908  Cheirurus  sp.  n.;  Delgado,  p.  80. 

Diagnosis.  Species  of  Actinopeltis  with  the  following  characteristics:  large,  inflated,  spherical 
anterior  part  of  glabella;  small  isolated  basal  glabellar  lobes  separated  from  inflated  glabellar  lobe 
by  long  (x<3g.)  furrow.  Eyes  situated  far  back,  with  eye  ridge  running  to  just  anterior  of  S2.  Pygidium 
with  four  pairs  of  spinose  pleurae;  posterior  pair  short  to  nearly  as  long  as  third  pair. 

Type  material.  Holotype:  SG  225,  part  and  counterpart  of  nearly  complete  individual.  Paratypes:  QXP  2.006, 
2.007,  2.026,  internal  moulds  of  incomplete  cephala.  QXP  2.041/2,  2.043/4,  parts  and  counterparts  of  pygidia. 

Horizon  and  locality.  SG  225  from  ‘500  mN  52°  E do  logar  do  Pereiro  (Magao)’.  Other  specimens  from 
' 1700  m N 57°  E de  pyr.  de  Queixoperra’,  Macao.  All  specimens  from  'Schistes  a Orthis  BerthoisV  (Delgado 
1908,  p.  80),  Queixoperra  Member  of  the  Cabego  do  Peao  Formation,  of  Caradoc  age. 

Derivation  of  name.  From  the  Portuguese  name  Rio  Tejo  (River  Tagus),  into  which  drain  the  rivers  of  the 
Magao  area. 

Description.  The  total  length  of  specimen  SG  225  is  28  mm  of  which  the  cephalon  constitutes  nearly  8 mm  and 
the  thorax  about  12  mm.  The  specimen  is  obliquely  deformed  and  crushed;  the  right  side  has  been  damaged. 

Cephalon  dominated  by  large,  approximately  spherical  anterior  part  of  glabella,  which  is  slightly  wider  than 
long  and  covered  with  small,  closely  spaced  tubercles  (barely  visible  on  internal  mould).  Narrow  (trans.) 
posterior  part  of  glabella  (though  varies  with  preservation)  comprises  pair  of  small,  nodular  basal  lobes, 
anterior  to  which  a broad  furrow  separates  them  from  inflated  anterior  part  of  glabella.  Occipital  furrow 
indistinct,  merging  with  transverse  furrow  anterior  to  LI  which  are  thus  isolated  at  abaxial  portions  of  broad 
(sag.)  furrow.  Occipital  ring  convex  (sag.  and  trans.)  and  carrying  similar  ornament  to  glabella.  Faint,  shallow 
S2  start  just  posterior  to  where  eye  ridge  meets  axial  furrow;  S2  possibly  directed  slightly  forwards  but 
fracturing  of  glabella  makes  this  uncertain.  Short,  shallow  S3  situated  approximately  level  to  where  lateral 
border  furrow  meets  axial  furrow.  Axial  furrows  deep,  without  sculpture,  and  widely  divergent. 

Cheeks  small,  triangular  in  outline,  highest  part  lying  adjacent  to  basal  glabellar  lobes.  Lateral  border 
strongly  convex,  of  more  or  less  constant  width,  extending  with  posterior  border  into  long  genal  spine  back 
to  at  least  seventh  thoracic  segment.  Genal  spine  oval(?)  in  cross-section  and  covered  with  small,  densely 


EXPLANATION  OF  PLATE  4 

Figs  1-9.  Prionocheilus  costai  (Thadeu,  1947).  1-3,  SG  160  (designated  lectotype);  internal  mould  and  latex 
cast  of  external  mould  of  nearly  complete  specimen,  dorsal  and  anterodorsal  views,  x 2-7,  x 3 and  x 3 
respectively,  Porto  de  Santa  Anna  Formation,  Bugaco,  Caradoc/ Ashgill.  4,  SG  2849;  latex  cast  of  external 
mould  of  incomplete  cephalon  and  thorax,  dorsal  view,  x 3,  Porto  de  Santa  Anna  Formation,  Bugaco, 
Caradoc/Ashgill.  5,  SG  162;  internal  mould  of  cephalon  and  part  thorax,  dorsal  view,  x 3,  Porto  de  Santa 
Anna  Formation,  Bugaco,  Caradoc/Ashgill.  6,  9,  SG  161 ; latex  cast  of  external  mould  and  internal  mould 
of  incomplete  specimen,  dorsal  views,  x 2-4,  Porto  de  Santa  Anna  Formation,  Bugaco,  Caradoc/Ashgill.  7 
and  8,  SG  163;  internal  mould  and  latex  cast  of  external  mould  of  nearly  complete  specimen,  dorsal  views, 
x 3 and  x 34  respectively,  Porto  de  Santa  Anna  Formation,  Bugaco,  Caradoc/Ashgill. 


PLATE  4 


ROMANO,  Prionocheilus 


350 


PALAEONTOLOGY.  VOLUME  34 


text-fig.  5.  Actinopeltis  tejoensis  sp.  nov.  Reconstruction  of  cephalon  and  pygidium. 


spaced  tubercles.  Prominent  eye  on  short  stalk,  situated  on  highest  part  of  cheek  and  fairly  close  to  posterior 
border  furrow.  Eye  lenses  visible  on  QXP.  2.002.  Well  marked,  low,  eye  ridge  runs  from  eye  to  axial  furrow 
just  anterior  to  where  S2  starts.  Anterior  branch  of  facial  suture  runs  anterolaterally  from  the  eye, 
approximately  parallel  to  axial  furrow,  to  margin.  Posterior  branch  curves  outwards  and  then  backwards  in 
even  curve  to  cut  lateral  margin  just  anterior  to  base  of  genal  spine.  Lateral  and  posterior  border  furrows  deep, 
except  around  base  of  genal  spine.  Posterior  border  convex  (exsag.);  narrowest  near  midline,  widening  evenly 
and  gradually  to  genal  spine.  Free  and  fixed  cheek  covered  with  coarse  pits  of  irregular  size  and  distribution. 

Thorax  consists  of  eleven  segments.  Axis  narrow,  strongly  convex,  and  delimited  by  rather  weak  axial 
furrows.  Axial  rings  gently  curved  forwards,  broadest  (sag.)  along  mid-line.  Rings  consist  of  convex  (sag.  and 
trans.)  posterior  band  which  broadens  laterally.  Anterior  part  of  ring  consists  of  broad,  nearly  flat  band  which 
narrows  toward  axial  furrow  where  there  is  a shallow  apodeme.  Convex  articulating  half-ring  separated  from 
axial  ring  by  marked  change  of  slope.  Pleurae  consist  of  inner  part  (approximately  one-third  their  transverse 
width)  which  is  flat  lying,  and  an  outer  spinose  part  which  is  outwardly  inclined.  Inner  part  of  pleural  segment 
consists  of  wide  (exsag.),  convex  band  bounded  by  narrow  anterior  and  posterior  bands.  Wide  band  carries 
rows  of  pits,  generally  about  6,  along  midlength  (appears  as  almost  continuous  groove  on  internal  mould). 
Posterior  pleural  band  is  constricted  at  the  fulcrum,  where  there  is  a prominent  fulcral  process  and  socket. 
Axial  rings  carry  fairly  dense  ornament  of  faint  tubercles  while  spinose  parts  of  pleurae  are  very  sparsely 
tuberculate. 

Pygidial  axis  about  one  and  a half  times  as  long  as  wide,  delimited  by  shallow  furrows  which  become  less 
well  defined  posteriorly.  Axis  consists  of  4 rings  which  decrease  in  length  posteriorly.  Ring  furrows  shallow 
medially.  Posterior  to  fourth  axial  ring  are  pair  of  short,  longitudinally  aligned  furrows  which  lie  in  series  with 
the  deeper  inner  parts  of  pleural  furrows.  Pleurae  consist  of  inner  flatfish  part  in  which,  from  front  to  back, 
pleurae  are  progressively  directed  more  posteriorly.  Pleural  furrows  end  in  deep  apodemal  pits  at  axis.  Outer 
parts  of  pleurae  are  slender  spines;  the  first  two  being  long,  slightly  curved  and  approximately  of  equal  length; 
the  third  is  a little  shorter  and  curved  proximally,  while  the  fourth  pair  are  much  shorter  (about  one-quarter 
as  long  as  second  pair  and  less  than  half  as  long  as  third  pair),  more  slender  and  directed  backwards.  In  one 
specimen  (QXP.  2.029a,  b)  the  fourth  pair  of  spines  are  considerably  longer  than  in  the  other  two  examples  and 


ROMANO:  PORTUGUESE  ORDOVICIAN  TRILOBITES 


351 


extend  posteriorly  to  terminate  level  with  the  tips  of  the  third  pair.  Axis  and  flat  pleural  region  carry  a few 
scattered  tubercles  while  the  spines  have  an  ornament  similar  to  that  of  the  glabella. 

Discussion.  The  genus  had  previously  been  recorded  in  Portugal  from  Valongo  and  Bugaco.  At 
Valongo,  Curtis  (1961)  recorded  A.  wattisoni  sp.  nov.  (referred  to  Valongia  wattisoni  by  Pfibyl  and 
Vanek  1984)  which  differs  from  the  Magao  species  in  possessing  12  thoracic  segments,  a less  swollen 
median  glabellar  lobe,  more  forwardly  placed  eyes  and  shorter  genal  spines.  The  ‘faint  horizontal 
rib  furrow’  which  Curtis  (1961,  p.  9)  described  appears  to  consist  of  a row  of  faint  pits  as  in  the 
present  material  (see  Curtis  1961,  plate  4).  Also,  the  pygidial  rib  furrows  on  wattisoni  may  be 
deformational  features.  At  Bugaco,  Delgado  (1908,  p.  57)  listed  a number  of  ‘ C he i rums ’ species 
from  the  upper  Ordovician,  some  of  which  have  been  more  recently  described  by  Thadeu  (1947). 
Of  these,  A.  aff.  completa  (Barrande)  (Thadeu  1947,  pi.  3,  figs  6 and  7)  from  the  Porto  de  Santa  Anna 
Formation  has  been  recently  compared  to  A.  vercingetorix  Pfibyl  and  Vanek  (1969)  by  Hammann 
(1974,  p.  105).  Both  of  these  species  show  a more  forwardly  placed  eye  and  coarser  sculpture  on  the 
glabella  than  Actinopeltis  tejoensis.  A.  spjeldnaesi  (Hammann  1972,  p.  372,  pi.  I,  fig.  3;  1974,  p.  102, 
pi.  12,  figs  200--207,  text-fig.  38;  1976,  p.  65,  pi.  5,  figs  64-68)  from  the  upper  Caradoc-lower  Ashgill 
(Hammann  et  at. , 1982,  p.  23)  of  Almaden  (Sierra  Morena,  Spain)  is  fairly  close  to  A.  tejoensis. 
Rabano  (1984)  considered  A.  spjeldnaesi  to  be  of  Caradoc  age.  The  Spanish  species  possesses  more 
forwardly  placed  eyes,  basal  glabellar  lobes  which  are  not  clearly  delimited  adaxially,  and  lacks  the 
broad  (sag.)  furrow  posterior  to  the  swollen  part  of  the  glabella.  The  anterior  pygidial  spines  are 
also  more  outwardly  flexed  in  A.  spjeldnaesi.  It  is  of  interest  to  note,  however,  that  in  both  A. 
spjeldnaesi  and  A.  tejoensis  the  fourth  pair  of  pygidial  spines  are  of  variable  length  (see  Hammann 
1974,  pi.  12,  fig.  203;  1976,  fig.  65;  and  PI.  3,  figs  7,  1 1 herein).  This  characteristic  appears  to  be 
independent  of  preservation. 

Delgado  (1908)  first  recorded  the  Magao  species  as  ‘ Cheirurus  sp.  n.  aff.  gryphus  Barrande’ 
(Barrande  1872,  pi.  3,  figs  10-17)  but  the  Bohemian  specimens  clearly  differ  from  the  Portuguese 
material  in  having  less  prominent  eyes  situated  closer  to  the  glabella  and  considerably  shorter  genal 
spines.  Among  other  Bohemian  species  of  Actinopeltis.  the  type  species,  A.  globosa  (Barrande  1852, 
pi.  35,  figs  1-7,  pi.  40,  figs  26  and  27,  pi.  43,  fig.  27;  Whittington  1968,  text-fig.  7,  p.  104),  and  the 
closely  related  A.  rivanol  (Snajdr,  1982)  have  less  well  delimited  LI  adaxially,  and  shorter  genal  and 
pygidial  spines;  the  latter  being  well  rounded  distally.  A.  insocialis  (Barrande,  1852,  pi.  40,  figs 
28-31)  does  not  possess  genal  spines,  and  the  pygidial  spines  are  shorter  and  rounded  at  the  ends. 
Kielan  (1959)  assigned  the  specimens  of  A.  insocialis  from  the  Kraluv  Dvur  beds  to  a new  species, 
A.  barrandei,  which  also  differs  from  Actinopeltis  tejoensis  in  the  absence  of  genal  spines,  the  very 
small  eye  and  the  only  slightly  pointed  pygidial  spines.  Actinopeltis  sp.  ‘a’  from  the  S.  clavifrons 
Zone  of  Poland  (Kielan  1959,  pi.  24,  fig.  4,  text-fig.  36)  has  a similar  structure  to  the  pygidial  axis 
as  Actinopeltis  tejoensis  but  the  tuberculation  is  coarser  and  more  densely  spaced. 


Genus  valongia  Pfibyl  and  Vanek,  1984 
Type  species.  Actinopeltis  wattisoni  Curtis,  1961. 


Valongia  wattisoni  (Curtis,  1961) 

*1961  Actinopeltis  wattisoni  sp.  nov.;  Curtis,  p.  8,  pi.  3,  fig.  2,  pi.  4,  fig.  1. 
1974  Actinopeltis  wattisoni  Curtis;  Hammann,  p.  105. 

1982  Actinopeltis  wattisoni ; Romano,  p.  96. 

1984  Valongia  wattisoni  (Curtis);  Pfibyl  and  Vanek,  p.  126,  fig.  4,  3. 
Material.  In  49184,  holotype.  part  and  counterpart  of  nearly  complete  specimen. 

Horizon  and  locality.  Upper  part  of  Valongo  Formation,  near  Covelo;  Llandeilo. 


352 


PALAEONTOLOGY, VOLUME  34 


Discussion.  The  species  was  described  and  figured  by  Curtis  (1961)  and  no  further  material  has  been 
found.  Curtis  assigned  the  species  to  Actinopeltis.  Recently  Pribyl  and  Vanek  (1984)  erected  a new 
genus,  Valongia , for  this  species  since  they  considered  the  specimen  showed  important 
morphological  features  which  distinguished  it  from  those  assigned  to  Actinopeltis.  These  included 
size  of  free  cheek,  course  of  facial  suture,  position  of  palpebral  lobes,  number  of  axial  segments  and 
structure  of  pygidial  axis.  The  present  author  is  in  agreement  with  Pribyl  and  Vanek  that  Curtis’ 
species  shows  significant  differences  from  those  of  Actinopeltis , but  is  more  reluctant  to  follow  their 
procedure  of  erecting  a new  genus,  based  on  a single  deformed  specimen.  However,  for  the  present, 
their  proposal  is  followed  here. 


Acknowledgements.  Drs  J.-L.  Henry  and  I.  Rabano  provided  information  on  Armorican  and  Spanish  material 
respectively;  Dr  M.  Ramalho,  Portuguese  Geological  Survey,  allowed  me  to  use  material  housed  in  Lisbon; 
Drs  A.  H.  Cooper  and  T.  Young  gave  me  access  to  their  personal  collections.  Miss  P.  Mellor  typed  the 
manuscript,  Mr  M.  Cooper  redrew  Text-figures  1—4,  and  Miss  G.  Thompson  photographed  the  specimens.  The 
work  was  carried  out  with  the  aid  of  NERC  Grant  GR3/3786. 


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shelf  ironstones  of  Western  Europe.  51-63.  In  young,  t.  p.  and  taylor,  w.  e.  g.  (eds).  Phanerozoic 
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MICHAEL  ROMANO 

Earth  Sciences  Unit 
University  of  Sheffield 

Typescript  received  7 August  1989  Beaumont  Building,  Brookhill 

Revised  typescript  received  11  April  1990  Sheffield  S3  7HF,  UK 


NOTE  ADDED  IN  PROOF 

After  this  manuscript  was  completed  the  author  was  kindly  sent  an  important  paper  by  Rabano 
(1990)  on  middle  Ordovician  trilobites  of  the  Central  Iberian  Zone  in  Spain.  Rabano  recognized 
S.  lusitanica  (Thadeu,  1949)  as  a distinct  species  and  pointed  out  that  it  was  distinguishable  from 
S.  salteri  by  a number  of  cephalic  features  (Rabano  1990,  pp.  120-122).  However,  the  variability  of 
the  sculpture  and  the  frequently  deformed  nature  of  the  Portuguese  specimens  do  not  allow 
confident  separation  of  these  two  forms.  Rabano  also  stated  that  S.  lusitanica  is  a characteristic 
species  of  the  Lower  Llanvirn  of  the  Central  Iberian  Zone,  and  designated  the  specimen  figured  by 
Thadeu  (1949),  pi.  2,  fig.  1)  as  the  lectotype.  This  specimen  (SG  71688)  was  collected  from  ‘ 1650  m 
[not  1680  m]  S 20°  O da  piramide  de  Santa  Justa  (Valongo)'.  From  the  same  locality,  Eccoptochile 
almadenensis,  E.  cf.  clavigera  and  Eodolmanitina  Ideslombesi  destombesi  occur.  The  known  ranges 
of  these  three  species  indicate  a Llandeilo  age  for  this  assemblage. 


REFERENCE 

rabano,  i 1990.  Trilobites  del  Ordovicico  Medio  del  sector  meridional  de  la  zona  Centroiberica  espanola. 
Publicaciones  especiales  de!  Boletin  Geologico  y Minero , 100  (for  1989),  1-233. 


CAMBROCLAVES  AND  PARACARINACHITIDS, 
EARLY  SKELETAL  PROBLEMATICA  FROM  THE 
LOWER  CAMBRIAN  OF  SOUTH  CHINA 

by  s.  conway  morris  and  CHEN  menge 


Abstract.  Cambroclaves  are  a major  group  of  sclerite-bearing  metazoans,  known  from  the  Lower  Cambrian 
of  China  (south  China,  Xinjiang),  USSR  (Kazakhstan)  and  Australia.  Zhijinites  longistriatus  Qian  is 
redescribed  on  the  basis  of  abundant  material  from  the  Hongchunping  Formation  at  Maidiping,  Sichuan. 
Sclerites  show  extensive  morphological  variability  and  have  a taphonomic  history  of  endolithic  infestation  and 
diagenetic  phosphatization,  the  latter  leading  to  replication  of  wall  ultrastructure.  Deiradoclavus  trigonus  gen. 
et  sp.  nov.  and  Deltaclavus  graneus  gen.  et  sp.  nov.  are  younger  cambroclaves  recovered  from  the  Guojiaba 
Formation  near  Kuanchuanpu,  Shaanxi,  and  the  Shuijingtuo  Formation  at  Taishanmiao,  Hubei.  Both  taxa 
bore  a cataphract  scleritome,  composed  of  interlocking  sclerites.  In  Deltaclavus  articulated  series  of  sclerites 
include  ‘arm-like’  structures.  Paracarinachitids  may  be  related  to  cambroclaves,  and  are  described  on  the  basis 
of  isolated  sclerites  of  Paracarinachites  spinus  Yu  from  the  Yuhucun  Formation  of  Meishucun,  Yunnan. 
Protopterygotheca  leshanensis  Chen  from  the  Hongchunping  Formation  of  Maidiping  is  included  in  the 
paracarinachitids,  and  is  described  on  the  basis  of  isolated  sclerites  bearing  prominent  flanges  on  either  side 
of  the  spatulate  axis.  The  primary  function  of  the  scleritomes  of  cambroclaves  and  paracarinachitids  may  have 
been  protective,  but  in  the  absence  of  intact  scleritomes  both  the  palaeoecology  and  affinities  of  these  groups 
are  uncertain.  The  new  class  Cambroclavida  is  proposed. 

The  irruption  of  skeletal  faunas  close  to  the  Precambrian-Cambrian  boundary  (Conway  Morris 
1987,  1989a)  has  attracted  wide  attention  on  two  principal  counts.  First,  there  is  debate  as  to 
whether  the  acquisition  of  skeletons  (a)  was  mediated  by  extrinsic  factors,  such  as  changes  in  ocean 
chemistry,  and/or  (b)  represents  a biological  response  such  as  providing  a defensive  cover  against 
durophagous  predators  and  offering  greater  support  to  soft  tissues.  The  second  point  of  discussion 
is  the  part  these  early  skeletal  faunas  played  in  the  major  adaptive  radiations  that  are  often  referred 
to  as  the  ‘Cambrian  explosion'.  Evidence  for  metazoan  diversification  is  readily  apparent  from  both 
the  record  of  trace  fossils  (Crimes  1989)  and  Burgess  Shale-type  soft-bodied  assemblages  (Conway 
Morris  1989^),  but  by  taphonomic  necessity  the  bulk  of  the  evidence  must  come  from  skeletal 
remains.  It  has  become  apparent  that  many  of  the  earliest  of  these  forms  are  of  problematic  affinity, 
bearing  no  clear  relationship  to  known  phyla.  Although  some  taxa  continue  to  languish  in  a 
taxonomic  limbo,  recent  work  has  demonstrated  the  presence  of  several  major  groups.  All  are 
extinct,  but  their  status  probably  deserves  the  cognomen,  in  terms  of  orthodox  taxonomy,  of 
phylum  on  account  of  their  distinctive  body-plans  (but  see  Conway  Morris  1989c).  Such  groups 
now  include  the  tommotiids,  coeloscleritophorans,  anabaritids,  cambroclaves  and  the  possibly 
related  paracarinachitids,  the  last  two  of  which  are  the  subject  of  this  paper.  With  the  exception  of 
the  tubicolous  anabaritids,  all  these  groups  share  a skeletal  arrangement  of  sclerites  that  presumably 
coated  the  exterior  body  to  form  the  scleritome.  Reconstruction  of  the  original  scleritome  ideally 
relies  on  articulated  material  such  as  might  occur  in  a Konservat-Lagerstatte.  With  the  halkieriids 
(Coeloscleritophora)  comparisons  with  the  Burgess  Shale  Wiwaxia  allowed  the  latter  to  act  as  a 
model  for  scleritome  reconstruction  (Bengtson  and  Conway  Morris  1984),  and  this  may  now  be 
tested  further  on  account  of  the  discovery  of  articulated  halkieriids  in  the  Lower  Cambrian  of  north 
Greenland  (Conway  Morris  and  Peel  1990).  In  the  remaining  cases,  however,  sclerite  arrangement 
must  be  inferred  from  either  rare  specimens  showing  fusion  or  functional  analysis  of  areas  of 
articulation  between  adjacent  sclerites. 


I Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  357-397,  9 pls.| 


© The  Palaeontological  Association 


358 


PALAEONTOLOGY,  VOLUME  34 


CAMBROCLAVES 

Cambroclaves  are  represented  by  a distinctive  group  of  sclerites  that  consist  of  a circular  to  oval 
base  that  bears  a spine,  usually  elongate.  They  are  recorded  from  the  Lower  Cambrian  of  China 
(Text-fig.  1),  Kazakhstan,  and  Australia.  However,  they  appear  to  be  unknown  from  other  parts  of 
the  world,  including  the  equivalent-aged  sections  in  Mongolia,  the  Siberian  platform,  and  Canada. 
In  the  past,  it  has  been  found  useful  to  make  a distinction  between  sclerites  with  a sub-circular  base 
bearing  a prominent  spine  (zhijinitid  morph)  and  those  with  a more  elongate  base,  often  having  a 
dumb-bell  shape,  with  the  spine  arising  from  the  anterior  half  (cambroclavid  morph).  The 
orientation  of  cambroclaves  follows  that  outlined  by  Mambetov  and  Repina  (1979,  fig.  8),  with  the 
prominent  spine  assumed  to  arise  from  the  anterior  end  of  the  dorsal  surface.  In  the  absence  of  any 
articulated  scleritomes,  overall  sclerite  attitude  with  respect  to  the  entire  animal,  assumed  to  be  a 
bilaterally  symmetrical  metazoan,  is  not  known. 

Scleritomes  that  appear  to  have  consisted  of  either  entirely  zhijinitids  or  predominantly 
cambroclavids  with  a small  proportion  of  zhijinitids  are  both  known.  The  former  type  is 
documented  in  some  detail  here  on  the  basis  of  Chinese  material  of  Zhijinites  longistriatus  Qian, 
while  cambroclavids  have  received  extensive  study  on  the  basis  of  well-preserved  material  of  a new 
species  of  Cambroclavus  from  South  Australia  (Bengtson  et  al.  1990).  Reconstructions  of 
cambroclave  scleritomes  may  also  be  inferred  with  varying  degrees  of  confidence  from  descriptions 
in  the  literature.  However,  the  wide  morphological  variability  of  the  sclerites  has  resulted  in 
excessive  use  of  form-taxa  by  some  authors,  and  one  aim  of  the  extensive  synonymy  list  proposed 
here  for  Z.  longistriatus  is  to  encourage  a classification  designed  to  lead  to  more  reliable  scleritome 
reconstructions.  In  addition  to  the  two  basic  sclerite  types  mentioned  above,  two  other  variants  are 
reported  on  the  basis  of  scleritomes  inferred  to  have  consisted  of  (a)  oval  sclerites  bearing  a ridge- 
like spine  ( Deiradoclavus  gen.  nov.),  and  (b)  sclerites  with  a predominantly  triangular  outline 
(Deltaclavus  gen.  nov.). 

The  first  report  of  cambroclaves  was  by  Zhong  [Chen]  (1977),  who  mentioned  and  illustrated 
material  from  Guizhou  and  Sichuan  provinces  as  Zhijinites  sp.  However,  as  none  of  the  formalities 
of  his  taxonomic  description  accords  to  those  laid  down  by  the  International  Commission  for 
Zoological  Nomenclature,  this  reference  to  Zhijinites  must  be  taken  as  a nomen  nudum.  Formal 
descriptions  of  Zhijinites  (Z.  longistriatus , Z.  minutus ),  on  the  basis  of  material  from  near  the  town 
of  Zhijin,  west  of  Guiyang  in  Guizhou  Province  (Text-fig.  1),  were  made  available  shortly 
afterwards  by  Qian  ( 1978a,  see  also  1978/)).  This  and  adjacent  localities  in  Guizhou  have  continued 
to  provide  abundant  material  of  Zhijinites  (Chen  1979;  Qian  and  Yin  1984 a,  b;  Wang  et  al. 
1984a,  b),  as  have  other  localities  (Text-fig.  1)  in  Sichuan  (Chen  1979;  Yin  et  al.  1980a,  b ; Yang  et 
al.  1983;  He  et  al.  1984),  Yunnan  (Jiang  1980,  1982;  Luo  et  al.  1984a)  and  Hubei  provinces  (Chen 
1979;  Qian  et  al.  1979).  Numerous  species  of  Zhijinites  have  been  erected,  most  of  which  are 
probably  synonymous  (see  below).  In  addition  the  genera  Heterosculpotheca  Jiang,  1982  and 
Parazhijinites  Qian  and  Yin  1984/),  are  both  regarded  as  junior  synonyms  of  Zhijinites.  Furthermore, 
what  are  evidently  specimens  of  Zhijinites  have  been  referred  to  the  conodont-like  Fomitchella  (Yin 
et  al.  1980a),  the  halkieriid  Sachites  (Yin  et  al.  1980a)  and  the  hyolith  Allatheca  (Yang  et  al.  1983). 

Notwithstanding  the  taxonomic  confusion  that  appears  to  accompany  our  existing  understanding 
of  Zhijinites  from  south  China,  in  the  majority  of  samples  it  seems  that  the  sclerites  are  derived  from 
the  dispersal  of  a scleritome  composed  exclusively  of  zhijinitid  morphs.  There  is,  however,  evidence 


text-fig.  1.  Distribution  of  cambroclaves  and  paracarinachitids  in  China.  The  numbers  refer  to  localities  from 
which  material  described  herein  has  been  recovered:  1,  Meishucun,  Yunnan  (see  Text-fig.  6);  2,  Maidiping, 
Sichuan  (see  Text-fig.  3);  3,  Taishanmiao,  Hubei  (see  Text-fig.  5);  4,  Xuanjiangping,  Shaanxi;  5,  Liangshan, 
Shaanxi  (for  both  see  Text-fig.  4).  In  addition  to  these  occurrences  cambroclaves  are  reported  also  from 
Xinjiang  province,  China  (Qian  and  Xiao  1984),  Kazakhstan,  USSR  (Mambetov  and  Repina  1979)  and 
Australia  (Bengtson  et  al.  1990).  Paracarinachitids  are  reported  also  by  Kerber  (1988)  from  southern  France. 


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that  in  some  stratigraphically  higher  cambroclaves  such  morphs  persisted  as  a minor  component  in 
a scleritome  otherwise  composed  of  cambroclavid  sclerites.  For  example,  in  reconstructing  an 
Australian  cambroclave  the  occasional  zhijinitid  morphs  were  regarded  as  an  integral  part  of  the 
scleritome  (Bengtson  et  al.  1990).  This  decision  was  based  on  the  presence  of  intermediate  forms 
which  showed  a progressive  reduction  of  the  posterior  end,  general  similarities  of  ornamentation, 
and  consistent  co-occurrence  with  the  more  abundant  cambroclavid  morphs.  It  is  for  this  reason 
that  a number  of  Chinese  species  placed  in  Zhijinites  are  regarded  tentatively  as  more  probably 
being  derived  from  a cambroclavid  scleritome,  rather  than  once  constituting  a scleritome  composed 
of  only  zhijinitids.  One  such  instance  might  be  Z.  intermedins , and  perhaps  Z.  claviformis , from  the 
Lower  Cambrian  Yurtus  Formation  of  Xinjiang  Province  (Qian  and  Xiao  1984)  that  could  be 
attributable  to  the  same  scleritome  that  yielded  elements  referred  to  Cambroclavus  ( = Sugaites ) 
bicornis.  Similarly,  zhijinitid  morphs  (Z.  claviformis , Z.  cordiformis)  co-occurring  with  cambroclavid 
sclerites  in  the  upper  Lower  Cambrian  (Damao  Group)  of  Yaxian  County,  Hainan  Island  (Text- 
fig.  1 ) (Jiang  and  Huang  1986)  may  all  be  derived  from  the  same  scleritome.  Duan  (1984)  described 
zhijinitid-morphs,  which  he  attributed  to  Tcinbaoites  ( T . porosus , T.  spiculosus)  from  the  Xihaoping 
Formation  of  Hubei  Province  (Text-fig.  1 ).  However,  they  co-occur  with  a plethora  of  cambroclavid 
taxa  (nine  species  placed  in  Cambroclavus , Sinoclavus  and  Phyllochiton)  that  may  all  be  derived  from 
a single  scleritome.  What  may  be  similar  cambroclavids  have  also  been  recorded  from  strata  of 
Atdabanian  age  from  a section  at  Xiaoyangba  in  Zhenba  County,  Shaanxi  (Text-fig.  1)  (Xie  1988, 
fig.  1). 

It  is  clear,  therefore,  that  until  a more  rigorous  approach  to  scleritome  reconstruction  in  Chinese 
cambroclaves  is  undertaken,  little  headway  can  be  expected  in  draining  the  swamp  of  form- 
taxonomy  that  mires  present  efforts  to  introduce  a degree  of  order.  This  is  also  exemplified  in  the 
interpretation  of  cambroclaves  from  Maly  Karatau  and  Talassky  Ala-Too,  Kazakhstan  (Mambetov 
in  Mambetov  and  Repina  1979;  see  also  Missarzhevsky  and  Mambetov  1981).  Mambetov  provided 
the  first  description  of  the  cambroclave  morph  in  the  form  of  Cambroclavus  antis.  In  addition  a 
zhijinitid-morph  was  distinguished  as  C.  undulatus , which  both  Jiang  (1982)  and  Duan  (1984) 
transferred  to  Zhijinites.  As  the  stratigraphic  range  of  C.  antis  and  Z.  undulatus  only  partly  overlap, 
it  is  possible  that  each  was  derived  from  a separate  scleritome.  It  is  also  conceivable,  however,  that 
the  concept  of  Z.  undulatus  is  incompletely  understood.  Zhijinitid-morphs  that  co-occur  with  C. 
antis  (Mambetov  in  Mambetov  and  Repina  1979,  pi.  13,  figs  2,  10,  13)  appear  to  differ  from  those 
collected  from  a separate  horizon  (Mambetov  in  Mambetov  and  Repina  1979,  pi.  13,  figs  1,  4,  11, 
12),  and  it  may  be  that  only  the  latter  belong  to  Zhijinites  s.s.,  having  been  derived  from  a scleritome 
composed  solely  of  zhijinitids.  Yet  another  type  of  cambroclave,  Pseudoc/avus  singularis  (Mambetov 
in  Mambetov  and  Repina  1979,  pi.  14,  figs  5,  7,  10,  11)  represents  a distinctive  variety  of 
cambroclave,  apparently  unique  to  Kazakhstan.  The  status  of  the  remaining  taxon,  C.  clavus , 
described  by  Mambetov  in  Mambetov  and  Repina  (1979,  pi.  13,  figs  3,  5,  7-9),  is  somewhat 
uncertain,  but  it  seems  to  be  a zhijinitid-like  morph  with  a conspicuous  spine  and  diminished  base. 

Although  sclerites  are  almost  invariably  found  isolated  owing  to  both  post-mortem  decay  of  any 
intervening  soft  tissue  and  the  exigencies  of  the  extraction  technique  of  acid  digestion  and  sieving, 
their  original  arrangement  may  be  preserved  in  rare  instances  as  fused  associations.  These  were 
noted  first  by  Mambetov  (in  Mambetov  and  Repina  1979,  pi.  14,  figs  6,  8,  9)  who  depicted  sclerites 
of  C.  antis  deployed  in  orderly  rows.  Amongst  the  well-preserved  cambroclavids  from  the 
Atdabanian  Ajax  Limestone  of  South  Australia  rare  examples  of  two  sclerites  fused  in  a 
longitudinal  direction  were  noted  (Bengtson  et  al.  1990).  Such  specimens  confirm  the  function 
of  the  anterior  ventral  and  posterior  dorsal  facets.  In  addition,  outline  shape  of  these  Australian 
cambroclavids  shows  how  they  would  have  interlocked  to  form  a cataphract  (chainmail-like) 
arrangement  (Text-fig.  1 1 b),  and  this  lends  credence  to  the  idea  that  the  sclerites  might  have  formed 
a protective  coating  on  a metazoan.  Analogies  to  the  wiwaxiids  and  halkieriids,  where  entire 
specimens  are  known,  might  suggest  that  cambroclaves  were  also  worm  or  slug-like.  However, 
unusual  examples  of  articulated  series  of  sclerites  in  Deltaclavus  graneus  gen.  et  sp.  nov.  (see  below) 
and  lack  of  knowledge  of  associated  soft  parts  makes  these  analogies  distinctly  tentative. 


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361 


The  analysis  of  the  new  Australian  species  of  Cambroclavus  also  revealed  the  sclerites  to  have  a 
very  wide  degree  of  morphological  variability,  encompassing  not  only  radical  differences  in  typical 
cambroclavid  types,  but  also  reduction  towards  a zhijinitid  condition  of  sub-circular  base 
surmounted  by  prominent  spine  (Bengtson  et  a/.  1990).  While  the  possibility  cannot  be  dismissed 
that  any  one  individual  bore  a restricted  range  of  sclerite  morphs,  it  is  considered  more  likely  that 
mutual  accommodation  in  shape  between  adjacent  sclerites  would  have  led  to  extensive  variation 
across  the  body.  For  the  most  part,  published  illustrations  of  cambroclaves  are  insufficient  to  gauge 
reliably  the  extent  of  morphological  variability.  However,  the  likelihood  of  extensive  synonymies 
within  suites  of  sclerites,  ostensibly  belonging  to  a plethora  of  nominal  taxa,  from  localities  such 
as  Hubei  (Duan  1984;  Qian  and  Yin  1984/))  and  Xinjiang  provinces  (Qian  and  Xiao  1984)  argue 
for  morphological  variability  being  widespread  in  cambroclaves. 


PARACARINACH1TIDS 

These  distinctive  sclerites  have  been  reviewed  critically  by  Qian  and  Bengtson  (1989),  who 
recognized  four  species  (the  type  species  Paracarinachites  sinensis , and  also  P.  columellatus,  P. 
parabolicus  and  P.  spinus).  Paracarinachitids  have  a narrow  spatula-like  form  with  a median  row 
of  spines,  and  evidently  grew  incrementally.  Although  best  known  from  South  China  (Qian  and 
Bengtson  1989),  sclerites  from  the  Montagne  Noire  of  southern  France  are  important  because  they 
show  also  a flange  (Kerber  1988).  Here,  we  describe  material  probably  attributable  to  P.  spinus , but 
differing  in  occurring  as  single  sclerites  rather  than  articulated  associations  where  the  sclerites  are 
arranged  in  a row.  In  Protopterygotheca  leshanensis  Chen  in  Qian  et  al .,  1979  sclerite  form  is 
especially  clear  on  account  of  well-developed  flanges,  but  the  diagnostic  paracarinachitid  spines  are 
only  seldom  evident.  Ultimately  it  may  transpire  that  Protopterygotheca  Chen,  1979,  should  be 
taken  as  a senior  synonym  of  Paracarinachites  Qian  and  Jiang,  1982  (see  Qian  and  Bengtson  1989), 
but  this  is  premature  on  existing  evidence.  Qian  and  Bengtson  (1989)  proposed  that  para- 
carinachitids and  zhijinitids  are  closely  related.  This  may  well  be  correct  for  P.  spinus , but  the 
remaining  three  species  of  Paracarinachites  (and  the  related  sclerites  of  Protopterygotheca  and 
Scoponodus)  may  be  better  treated  as  a group  distinct  from  the  cambroclaves.  In  addition,  the 
possibility  that  Ernogia  (see  Qian  and  Bengtson  1989,  pp.  100-102,  figs  64  and  65)  be  included  in 
the  roster  of  paracarinachitids  may  also  bear  further  consideration.  Qian  and  Bengtson  (1989) 
considered  this  option  briefly,  on  account  of  both  overa'l  shape  and  growth  incrementation.  The 
nodular  ornamentation  on  the  exterior  of  Ernogia  stands  in  contrast  to  the  median  spines  of 
Paracarinachites , but  this  difference  may  be  of  relatively  minor  importance  given  the  more  or  less 
smooth  appearance  of  most  sclerites  of  P.  leshanensis  described  herein. 


STRATIGRAPHY  AND  LOCALITIES 
The  material  described  herein  comes  from  the  following  horizons  and  localities: 

1.  Zhijinites  longistriatus.  All  the  material  illustrated  here  was  obtained  from  Beds  36  and  37  of  the 
Maidiping  Member,  Hongchunping  Formation  (Text-fig.  2),  exposed  at  the  Maidiping  section  near  to  Emei, 
Sichuan  Province  (Text-fig.  3).  This  section  is  one  of  many  Precambrian-Cambrian  Boundary  sections  located 
around  Emei  Mountain  (see  He  et  al.  1984,  fig.  4-1),  but  its  stratigraphy  and  fossil  content  have  received 
particularly  detailed  attention  by  several  workers  (e.g.  Yin  et  al.  I980«,  />;  He  and  Yang  1982;  He  et  al.  1984). 
Zhijinitids  were  reported  by  Zhong  [Chen]  (1977,  p.  123),  Chen  (1979,  p.  281),  and  Yin  et  al.  (1980«,  pp. 
178-179;  see  also  synonymy  list  for  apparently  erroneous  assignments  to  Fomitchella  and  Sachites  hastatus). 

Comparable  material  was  obtained  from  the  Dananguo  section,  Liangshan  (Text-fig.  4),  located  3 km  from 
the  Oriental  Instrument  Plant  factory  and  10  km  north-west  of  Hanzhong  (Fu  1983,  fig.  1 ; Ding  et  al.  1983, 
fig.  2).  Here  the  Yangjiakon  member  of  the  Dengying  Formation  (Text-fig.  2)  (Fu’s  placement  of  this  part  of 
the  section  in  the  Guojiaba  Formation  is  less  likely,  because  correlations  suggest  it  to  be  equivalent  to  the 
deeper  water  Kuanchuanpu  Member  exposed  west  of  Hanzhong  in  the  Ningqian  area  (see  Xing  and  Yue  1984; 
Conway  Morris  and  Chen  1989))  is  composed  near  its  top  of  sandy  glauconitic  limestones.  It  yields  abundant 
zhijinitids  (Fu  1983;  Ding  et  al.  1983)  which,  however,  are  generally  somewhat  smaller  than  those  recovered 


362 


PALAEONTOLOGY,  VOLUME  34 


^^^Region 

Strata 

East  Yunnan 
(Meishucun) 

West  Hubei 
(Taishanmiao) 

Southwest  Shaanxi 
(Xuanjiangping 
& Liangshan) 

Southwest  Sichuan 
(Maidiping) 

Qiongzhusi 

Yu anshan 

Upper 

Upper 

Stage 

Qiongzhusi 

Member 

Shuijingtuo 

Guojiaba 

Member 

Jiulaodong 

Member 

Fm. 

Badaowan 

Fm. 

Fm. 

Lower 

Fm. 

Lower 

Z 

< 

Member 

Member 

Member 

DC 

DO 

S 

< 

O 

0> 

cn 

CD 

55 

c 

3 

O 

Dahai 

Member 

Tianzhu  - 

Maidiping 

Member 

3 

SZ 

</> 

0) 

Zhongyicun 

shan 

Member 

SE 

Member 

Dengying 

(Huangshan- 

Dengying 

Kuanch- 

Hongchun- 

Yuhucun 

dong 

uanpu 

ping 

Fm. 

Xiaowai  - 

toushan 

Member 

Fm. 

Member) 

Fm. 

Member 

Fm. 

z 

< 

z 

0) 

cn 

CD 

55 

CD 

X 

Baiyanshao 

Member 

Biamatuo 

Member 

Maoergang 

Member 

w 

c 

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cn 

c 

0) 

-Jiucheng 

Member 

Shibantan 

Member 

o 

text-fig.  2.  Summary  stratigraphic  chart  for  the  Sinian-Cambrian  boundary  sequence  in  South  China  (see 
Text-fig.  I for  position  of  localities).  Asterisked  arrows  refer  to  stratigraphic  horizons  of  occurrence  of 
cambroclaves  and  paracarinachitids,  see  text  for  further  details.  Based  on  table  8-1  of  Ding  et  al.  (1984). 

from  Maidiping.  In  addition  to  zhijinitids  the  productive  sample  yielded  also  abundant  Hyolithellus,  rare 
Protohertzina  (cf.  Fu  1983)  and  spicules.  From  the  overlying  shales  of  the  Guojiaba  Formation  (equivalent  to 
the  Qiongzhusi  Formation)  at  Liangshan  Chen  (1985)  has  described  trilobites. 

2.  Deiradoclavus  trigonus  gen.  et  sp.  nov.  Abundant  specimens  were  recovered  from  a calcareous  horizon 
(thin  limestones  overlying  beds  with  calcareous  concretions)  in  the  otherwise  largely  clastic  Guojiaba 
Formation  (Text-fig.  2)  (see  Chen  et  al.  1975,  fig.  2).  The  outcrop  forms  part  of  the  Xuanjiangping  section,  and 
is  located  in  a stream  about  1 500  m southeast  of  the  hamlet  of  Xuanjiangping  (Text-fig.  4).  The  underlying 
strata,  especially  of  the  Kuanchuanpu  Formation,  have  received  extensive  attention  on  account  of  their 
abundant  small  skeletal  fossils  and  proximity  to  the  Precambrian-Cambrian  Boundary  (e.g.  Shizhonggou 
section,  Xing  and  Yue  1984;  Xing  et  al.  1984;  Piaojiaya  section  (Text-fig.  4),  Conway  Morris  and  Chen  1989). 
However,  apart  from  reports  of  Tommotia  (Qin  and  Yuan  1984),  the  small  skeletal  fossils  of  the  Guojiaba 
Formation  appear  to  have  received  little  attention.  In  addition  to  Deiradoclavus  the  sample  yielded  Tannuolina 
zhangwentangi  (Conway  Morris  and  Chen  19906;  Qin  and  Yuan’s  (1984)  report  on  Tommotia  may  refer  to  this 
taxon),  Pelagiella  sp.,  Actinotheca , bradoriids,  unidentified  tubes,  and  other  problematica. 

3.  Deltaclavus  graneus  gen.  et  sp.  nov.  Abundant  material  was  recovered  from  the  lower  Shuijingtuo 
Formation  (Text-fig.  2;  see  also  Zhou  and  Xu  1987),  exposed  in  the  Taishanmiao  section,  near  the  village  of 
Taishanmiao,  Hubei  Province  (Text-fig.  5).  The  sample  was  a fallen  block  in  a roadside  quarry  about  250  m 
south  of  the  Precambrian-Cambrian  Boundary  as  locally  defined  within  the  Tianzhushan  member  of  the 


CONWAY  MORRIS  AND  CHEN:  CAMBRIAN  PROBLEMATICA 


363 


text-fig.  3.  Locality  map  of  region  around  Emei  (Sichuan),  showing  location  of  Maidiping  section 
(asterisked).  Based  on  fig.  1 of  Yin  et  al.  (19806)  and  fig.  4.1  of  He  et  al.  (1984). 


Dengying  Formation  (see  Conway  Morris  and  Chen  (1990a)  for  further  details  of  locality  and  associated 
fauna,  including  the  problematic  Blastu/ospongia). 

Despite  a variety  of  stratigraphic  terms,  for  the  most  part  correlation  of  the  Lower  Cambrian  around  the 
Yangtze  platform  of  South  China  (Text-fig.  2)  is  reasonably  straightforward  (e.g.  Xing  el  al.  1984).  Accepting 
the  existing  scheme  of  correlations  it  would  appear  that  the  zhijinitids  from  Maidiping  (Sichuan)  and 
Meishucun  (and  Liangshan,  Shaanxi)  are  of  approximately  the  same  age,  falling  into  the  lower  part  of  the 
Paragloborilus-Siphogonuchites  assemblage.  Deiradoclavus  gen.  nov.  from  the  lower  Guojiaba  Formation 
(Shaanxi)  and  Deltaclavus  gen.  nov.  from  the  lower  Shuijingtuo  Formation  are  somewhat  younger,  and  about 
the  same  age  as  one  another.  These  two  genera  appear  to  be  closely  related,  and  it  is  to  be  expected  that  similar 
canrbroclaves  will  be  found  in  due  course  in  equivalent  strata  such  as  the  Badaowan  member  of  the  Qiongzhusi 
Formation  (Yunnan)  and  the  Jiulaodong  Formation  (Sichuan)  (Text-fig.  2).  These  are  predominantly  clastic 
units,  but  so  far  investigation  of  carbonate  horizons  in  both  formations  (Conway  Morris  and  Chen,  19906;  see 
also  Qian  and  Bengtson  1989)  has  not  revealed  any  material. 

4.  Paracarinachites  spinas.  Numerous  specimens  were  recovered  from  dolomites  of  Bed  7 of  the  Zhongyicun 
member,  Yuhucun  Formation  (Text-fig.  2)  exposed  at  the  Xiawaitoushan  section  of  the  Kunyang  Phosphorite 
Mine,  at  Meishucun,  Yunnan  Province  (Text-fig.  6)  (Luo  et  al.  1980,  1982,  1984a,  b).  The  Meishucun  locality 
has  attracted  widespread  interest  on  account  of  it  being  the  Chinese  stratotype  candidate  for  the 
Precambrian-Cambrian  Boundary.  To  date,  this  taxon  has  been  chiefly  documented  from  articulated  series  of 
sclerites  from  this  horizon  and  the  overlying  Bed  8 of  the  Dahai  Member  (Text-fig.  2)  (see  Qian  and  Bengtson 


364 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  4.  Locality  map  of  region  near  Hanzhong  (Shaanxi),  showing  locations  of  section  near  Liangshan 
(asterisk  on  main  map)  and  near  Xuanjiangping  (asterisk  on  inset  map),  and  also  Piaojiaya  section  (see 
Conway  Morris  and  Chen  1989).  Based  on  fig.  6-1  of  Xing  and  Yue  (1984). 


1989;  He  and  Xie  1989),  and  the  abundant  isolated  sclerites  are  less  well  known  (He  and  Xie  1989,  pi.  I,  figs 
20  and  22). 

5.  Protopterygotheca  leshanensis.  This  material,  which  only  seldom  has  the  median  spines  diagnostic  of  other 
paracarinachitids  present,  was  obtained  from  the  same  horizons  at  Maidiping,  Emei  (Text-fig.  3)  as  the 
specimens  of  Z.  longistriatus  (see  above).  The  type  material  of  this  taxon  comes  from  the  Tianzhushan  section 
in  Hubei  (Text-fig.  5). 


SYSTEMATIC  DESCRIPTIONS 
Class  CAMBROCLAVIDA  nov. 

Diagnosis.  Calcareous)  ?)  sclerites  with  variously  shaped  base  bearing  an  elongate  spine,  forming  a 
scleritome  that  ranged  from  articulated  cataphract  array  to  individual  sclerites  studding  surface, 
apparently  separated  by  unmineralized  tissue. 


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365 


text-fig.  5.  Locality  map  of  region  around  Yichang  (Hubei),  showing  location  of  Taishanmiao  and 
Tianzhushan  sections  (asterisked).  Based  on  fig.  2-1  of  Chen  et  al.  (1984). 


Family  zhijinitidae  Qian,  1 978c/ 

Emended  diagnosis.  Sclerites  composed  of  base  and  elongate  spine,  now  hollow,  formerly  filled  with 
soft  tissue?  Base  may  be  subcircular  to  elongate.  In  the  latter  case  it  may  have  prominent 
constriction  imparting  dumb-bell  shape,  and  usually  articulatory  facets.  Dorsal  surface  or- 
namentation frequently  of  radiating  low  ridges.  Spine  elongate,  usually  recurved  posteriorly, 
transverse  section  varies  from  circular  to  elongate.  Original  composition  probably  calcareous. 

Component  genera.  (1)  Zhijinites  Qian,  1978a  (junior  synonyms  include  Sachites  sensu  Yin  et  al ., 
1980a,  non  Meshkova,  1969;  Fomitchella  sensu  Yin  et  al .,  1980a,  non  Missarzhevsky  in  Rozanov  et 
al .,  1969;  Heterosculpotheca  Jiang,  1982;  Parazhijinites  Qian  and  Yin,  19846).  (2)  Cambroclavus 
Mambetov  in  Mambetov  and  Repina,  1979  (junior  synonyms  include  Phyllochiton  Duan,  1984; 
Sinoclavus  Duan,  1984;  Sugaites  Qian  and  Xiao,  1984;  and  probably  Isoclavus  Qian  and  Zhang, 
1983;  Tanbaoites  Duan,  1984;  Wushichites  Qian  and  Xiao,  1984;  and  Zhijinites  (in  part)  sensu  Qian 
and  Xiao,  1984;  and  Jiang  and  Huang,  1986;  see  above).  (3)  Deiradoclavus  gen.  nov.  (4)  Deltaclavus 
gen.  nov. 


zhijinites  Qian,  1 9 7 8 cv 


Type  species.  Zhijinites  longistriatus  Qian,  1978a. 


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PALAEONTOLOGY,  VOLUME  34 


text- fig.  6.  Locality  map  of  region  around  Meishucun  (Yunnan),  showing  location  of  Bed  7 of  the 
Xiaowaitoushan  section  (asterisked).  Based  on  figs  1 and  2 of  Luo  et  al.  (1984/)). 


Diagnosis.  Sclerite  base  subcircular  to  somewhat  elongate,  ventral  base  gently  concave,  dorsal 
surface  convex.  Margin  usually  entire,  occasionally  with  prominent  cleft  that  may  be  enclosed  to 
leave  perforation.  Spine  elongate,  inclined,  more  or  less  straight.  Transverse  section  of  spine 
variable  from  subcircular  to  concavo-convex,  ornamentation  variable,  including  prominent 
transverse  ridges,  longitudinal  ribbing  to  more  or  less  smooth. 


Zhijinites  longistriatus  Qian,  1 978c/ 

Plates  1-3;  Text-figs  7 and  1 la 

1977  Zhijinites  sp.  Zhong  [nomen  nudum],  p.  123,  pi.  3,  fig.  7;  pi.  4,  figs  22-27. 
1978a  Zhijinites  longistriatus  Qian,  p.  34,  pi.  2,  fig.  5a,  b. 

1978 b Zhijinites  longistriatus  Qian,  p.  350,  pi.  142,  fig.  5a,  b. 

1978a  Zhijinites  minutus  Qian,  p.  34,  pi.  2,  fig.  6 a-c. 

1978/)  Zhijinites  minutus  Qian,  p.  350,  pi.  142,  fig.  4a-c. 

1979  Zhijinites  annae  Chen  [nomen  nudum],  p.  281,  fig.  id. 

1979  Zhijinites  costatus  Chen  [nomem  nudum],  p.  281,  fig.  3 b. 

1979  Zhijinites  dictyoformise  Chen  [nomen  nudum],  p.  281,  fig.  ie. 

71979  Zhijinites  lubricus  Qian  et  al.,  p.  225,  pi.  4,  figs  14  and  15. 

1979  Zhijinites  minutus  Lu.  pi.  1.  figs  6 and  7. 

1979  Zhijinites  longistriatus  Lu,  pi.  1,  figs  19  and  20;  pi.  2,  figs  2 and  1 1. 

71980  Zhijinites  lubricus  Zhao  et  al.,  p.  49,  pi.  3,  fig.  21. 

71980a  Zhijinites  lubricus  Yin  et  al.,  p.  178,  pi.  19,  figs  1 1 and  12. 

1980a  Zhijinites  longistriatus  Yin  et  al.,  p.  179,  pi.  19,  figs  8 and  10. 

1980a  Zhijinites  minutus  Yin  et  al.,  p.  179,  pi.  19,  fig.  9. 

71980a  Fomitchella  sp.  Yin  et  al.,  pi.  19,  fig.  7. 

1980a  Sachites  hastatus  Yin  et  al.,  p.  195,  pi.  18,  fig.  9 (?non  pi.  18,  fig.  30). 
71980/)  Zhijinites  lubricus  Yin  et  al.,  p.  65. 

1981  Zhijinites  minutus  Xiang  et  al..  pi.  1,  fig.  15. 

1982  Zhijinites  longistriatus  Yin  et  al.,  pp.  287,  291. 


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367 


1982  Zhijinites  minutus  Yin  et  al .,  pp.  287,  291. 

1982  Zhijinites  longistriatus  Jiang,  p.  181,  pi.  17,  figs  8,  9,  19. 

71982  Zhijinites  lubricus  Jiang,  p.  182,  pi.  17,  fig.  13. 

1982  Zhijinites  minutus  Jiang,  p.  182,  pi.  17,  figs  6,  7,  20. 

71982  Zhijinites  undulatus  Jiang,  p.  182,  pi.  17,  fig.  1 1 (non  fig.  12,  \2a  7 = Paracarinachites  spinus). 

71982  Zhijinites  umbelletes  Jiang,  p.  182,  pi.  17,  fig.  10,  10a. 

1982  Heteroscu/potheca  pheneres  Jiang,  p.  166,  pi.  13,  figs  23,  23a,  24,  25. 

71983  Zhijinites  lubricus  Fu,  p.  416,  pi.  1,  figs  12  and  13. 

71984  Zhijinites  lubricus  Qian,  pi.  3,  fig.  8. 

1984  Zhijinites  minutus  Qian,  pi.  3,  fig.  7. 

71984  Zhijinites  sp.  Qian,  pi.  3,  fig.  16. 

71983  Allatheca  nanjiangensis  [nomen  nudum]  Yang  et  a/.,  p.  95,  pi.  1,  fig.  14. 

1984a  Zhijinites  longistriatus  Qian  and  Yin,  pi.  4,  fig.  14. 

1984a  Zhijinites  minutus  Qian  and  Yin,  pi.  5,  fig.  14. 

1984 b Zhijinites  longistriatus  Qian  and  Yin,  pp.  215,  218,  pi.  1,  figs  12-15. 

1984 b Zhijinites  cordiformis  Qian  and  Yin,  pp.  215,  219,  pi.  1,  figs  20-23. 

19846  Zhijinites  minutus  Qian  and  Yin,  pp.  215,  218,  text-figs  1.3  and  3c.  1,  2;  pi.  1,  figs  1-11 
19846  Zhijinites  panduriformis  Qian  and  Yin,  pp.  215,  218,  219,  pi.  1,  figs  16-19. 

19846  Zhijinites  triangularis  Qian  and  Yin,  pp.  215,  219,  pi.  2,  figs  14-21. 

719846  Parazhijinites  quizhouensis  [sic]  Qian  and  Yin,  p.  220,  text-fig.  3.3;  pi.  2,  figs  1-8. 

1984a  Zhijinites  longistriatus  Wang  et  al .,  pi.  22,  figs  13  and  14. 

1984a  Zhijinites  minutus  Wang  et  al.,  pi.  22,  figs  14. 

1984a  Zhijinites  panduriformis  Wang  et  al..  p.  177,  pi.  22,  figs  9-12. 

71984a  Parazhijinites  guizhouensis  Wang  et  al.,  p.  177,  pi.  22,  figs  5-8. 

19846  Zhijinites  longistriatus  Wang  et  al.,  pi.  4,  fig.  9. 

19846  Zhijinites  minutus  Wang  et  al.,  pi.  5,  fig.  14. 

1984a  Zhijinites  minutus  Luo  et  al.,  pi.  10,  fig.  24. 

1984  Heterosulpotheca  [sic]  phaneres  [sic]  Jiang,  fig.  4.3. 

1984  Heterosulpotheca  [sic]  phoneres  [sic]  Jiang,  pi.  2,  fig.  8. 

1984  Zhijinites  minutus  Jiang,  pi.  3,  fig.  11. 

71987  Parazhijinites  quizhouensis  [sic]  Liu,  fig.  3a. 

71987  Zhijinites  triangularis  Liu,,  fig.  3b. 

1989  Zhijinites  sp.  Chen,  pi.  1,  fig.  1. 

Diagnosis.  As  for  the  genus. 

Holotype.  Institute  of  Geology  and  Palaeontology,  Academia  Sinica,  Nanjing,  ASN  33676  (Qian  1978a,  pi.  2, 
fig.  5). 

Material  illustrated  here.  Institute  of  Geology  (Beijing),  Academia  Sinica  IGAS-BC-88-30079-301 12. 

Stratigraphic  horizon.  Beds  36  and  37,  Maidiping  Member,  Hongch unping  Formation,  Meishucun  Stage, 
Lower  Cambrian  (see  Yin  et  al.  1980a,  6 and  He  et  al.  1984  for  further  details). 

Locality.  Maidiping  section,  Emei,  Sichuan. 

Preservation.  The  majority  of  specimens  consist  of  sclerites  with  a phosphatized  wall  enclosing  a central  cavity 
(Text-fig.  7).  Petrographic  sections  demonstrate  that  the  extent  of  phosphatization  varies  quite  widely,  and  may 
include  obvious  spherulitic  ingrowths  on  the  interior  of  the  spine  cavity  (Text-fig.  76).  The  dorsal  side  of  the 
base  is,  apart  from  radial  furrows,  often  relatively  smooth  (e.g.  PI.  1,  figs  1,  3,  16,  17;  PI.  2,  figs  4,  8,  13).  It 
is  frequent  on  the  spine,  however,  for  surfaces  to  be  more  irregular,  consisting  of  a fibrous  ultrastructure 
running  parallel  to  the  long  axis  of  the  spine  (PI.  1,  figs  5,  11-14,  16;  PI.  2,  figs  1 and  10).  This  fibrosity  is 
interpreted  as  diagenetic  phosphatization  of  an  originally  calcareous  wall.  In  addition,  endolithic  borings  are 
also  abundant  in  some  specimens.  These  may  be  visible  as  openings  on  the  surface  of  the  base  (PI.  1,  figs  8 and 
9),  or  as  steinkerns  of  tubes  that  run  along  the  spine  (PI.  3,  figs  1-3,  9,  12).  The  tubes  consist  of  two  distinct 
size  classes  (c.  3 /mi  and  7 /mi  diameter  respectively).  The  larger  category  possesses  a series  of  swellings, 
sometimes  locally  pronounced,  that  impart  a beaded  appearance  (PI.  3,  figs  10  and  13)  and  may  end  blindly 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  7.  Petrographic  thin  sections  of  Zhijinites  longistriatus  Qian,  1978  from  Beds  36  (a-c,  e , g and  h)  and 
37  (</,/),  Maidiping  Member,  Hongchunping  Formation  at  Maidiping  section,  Emei,  Sichuan,  China,  to  show 
varying  degrees  of  diagenetic  phosphatization.  a , IGAS-BC-88-30199,  distal  portion  of  spine  abraded,  x 66. 
6,  IGAS-BC-88-30200,  note  spherulitic  growths  into  central  cavity,  x 66.  c,  IGAS-BC-88-30201,  note  abraded 
tip  and  incomplete  phosphatization,  x 45.  d , IGAS-BC-88-30202,  x 38.  e,  IGAS-BC-88-30203,  x 22./,  IGAS- 
BC-88-30204,  note  incomplete  phosphatization  of  base,  x43.  g and  /;,  IGAS-BC-88-30205 ; g , note  restricted 
degree  of  phosphatization,  x 33;  h,  detail  of  proximal  area  with  septum  between  cavities  of  spine  and  base 

respectively,  x 135. 


(PI.  3,  fig.  7).  The  borings  run  sub-parallel,  but  may  recurve  or  arch  over  each  other  near  points  of  contact 
(PI.  3,  fig.  1 1 ).  The  smaller  tubes  are  generally  more  filiform  (PI.  3.  figs  10  and  1 1),  may  show  branching  and 
only  locally  possess  swellings  in  diameter. 

The  other  principal  type  of  preservation  is  as  steinkerns  of  the  spine  (PI.  2,  fig.  16;  PI.  3,  figs  4-6).  These  were 
regarded  as  a separate  taxon,  referred  to  as  Heterosculpotheca  pheneres  by  Jiang  (1982,  pi.  13,  figs  23,  23 a,  24, 
25),  which  is  taken  here  as  a junior  synonym  of  Zhijinites  longistriatus.  Their  origin  can  be  confirmed,  both 
from  Jiang’s  (1982)  illustrations  (especially  his  pi.  13,  figs  23 a and  25)  which  show  the  characteristic  transverse 
ornamentation  of  the  spines,  and  the  identical  ultrastructure  of  the  steinkern  surface  as  seen  in  isolated 
specimens  and  in  exposed  patches  beneath  the  wall  of  more  complete  individuals  (see  Runnegar  1985  for 
similar  examples  of  ultrastructural  replication).  The  ultrastructure  consists  of  longitudinal  lineations  that  have 
a stepped  appearance  along  irregular  re-entrants  (PI.  2,  fig.  17;  PI.  3,  figs  8,  10,  1 3).  In  addition  the  surface  bears 
elongate  pores  (PI.  3,  fig.  4)  that  mark  the  course  of  tubes  that  enter  the  steinkern  at  shallow  angles. 


EXPLANATION  OF  PLATE  1 

Figs  1-19.  Zhijinites  longistriatus  Qian,  1978.  1 and  2,  IGAS-BC-88-30079.  3 and  4,  IGAS-BC-88-30080.  5, 
IGAS-BC-88-3008 1 . 6 and  7,  1GAS-BC-88-30082.  8 and  9,  IGAS-BC-88-30083.  10,  IGAS-BC-88-30084.  1 1 
and  12,  IGAS-BC-88-30085.  13.  IGAS-BC-88-30086.  14  and  15,  IGAS-BC-88-30087.  16,  IGAS-BC-88- 
30088.  17,  IGAS-BC-88-30089.  18  and  19,  IGAS-BC-88-30090.  All  isolated  sclerites  from  Bed  36,  Maidiping 
Member,  Hongchunping  Formation  at  Maidiping  section,  Emei,  Sichuan,  China.  Magnification  all  x 70. 


PLATE  1 


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370 


PALAEONTOLOGY,  VOLUME  34 


Description.  The  overall  form  of  a circular  base  bearing  an  elongate  spine  is  subject  to  considerable  degrees  of 
morphological  variation  (PI.  1,  figs  1-19;  PI.  2,  figs  1-9,  1 1-15),  The  basal  unit  is  concave-convex,  and  in  the 
majority  of  specimens  more  or  less  circular.  However,  elongate  and  more  irregular  forms  (PI.  1,  figs  5,  18,  19; 
PI.  2,  figs  7 and  15)  are  also  known.  A more  persistent  trait  is  the  presence  of  an  embayment  or  notch  on  the 
anterior/posterior  margin  (PI.  1.  figs  13  and  16).  In  most  specimens  there  is  only  a single  embayment,  but 
occasionally  several  occur  adjacent  to  one  another  in  one  sclerite.  In  some  individuals  this  feature  is  open,  but 
in  others  it  is  tightly  incised  so  that  ultimately  it  consists  of  a perforation  through  the  base,  connected  to  the 
margin  by  a ligatural  line  (PI.  2,  fig.  6). 

The  concave  ventral  side  of  the  base  appears  to  have  been  smooth  (PI.  I,  fig.  10;  PI.  2,  fig.  5),  but  the  dorsal 
surface  characteristically  bears  an  ornamentation  of  irregular  furrows  (PI.  1,  figs  3,  4,  6-9,  14-19;  PI.  2,  figs 
4.  10,  11).  Where  the  base  is  circular  these  furrows  have  a radial  disposition,  whereas  in  more  elongate  sclerites 
the  ornamentation  shows  a corresponding  linearity. 

The  elongate  spine  generally  arises  eccentrically,  although  whether  nearer  to  the  anterior  or  posterior  margin 
depends  on  possible  homologies  with  the  cambroclavid  sclerites.  If  the  spine  is  anterior,  as  in  cambroclavids 
(Mambctov  in  Mambetov  and  Repina  1979;  Bengtson  et  al.  1990),  then  in  contrast  to  the  cambroclavids 
the  zhijinitid  spine  was  sometimes  inclined  anteriorly  (e.g.  PI.  1,  figs  4,  9,  16;  PI.  2,  figs  3,  8,  12,  13).  If  the  spine 
is  posterior,  then  the  marginal  notch  (when  present)  would  be  consistently  located  on  the  anterior  margin  (PI. 
1,  figs  13  and  16;  PI.  2,  fig.  6),  whereas  in  cambroclavids  it  is  usually  on  the  posterior  margin  (e.g.  Qian  and 
Zhang  1983,  pi.  3,  figs  9,  1 1,  12,  14,  16;  Duan  1984.  pi.  5,  figs  16a,  b and  17a,  c\  Qian  and  Xiao  1984,  pi.  1, 
figs  7 and  13;  pi.  3,  figs  II,  16,  18;  see  Bengtson  et  al.  1990  for  proposed  synonymies  of  the  taxa  erected 
by  these  Chinese  workers). 

In  the  majority  of  sclerites  the  area  of  insertion  of  the  spine  occupies  a relatively  small  proportion  of  the 
dorsal  surface  (PI.  1,  figs  3,  4,  6,  15;  PI.  2,  figs  4 and  1 1).  In  a few  individuals  the  ratio  between  spine  and  base 
is  greatly  increased  (PI.  2,  figs  1 and  9),  although  incomplete  margins  often  make  it  difficult  to  determine  the 
exact  proportions.  The  spine  arises  from  the  base  at  varying  angles,  ranging  from  more  or  less  right  angles  (PI. 

1,  fig.  19;  PI.  2,  figs  9 and  15)  to  about  45°,  the  latter  being  more  common.  The  distal  end  of  the  spine  is  almost 
invariably  absent,  but  it  is  clear  that  the  length  varied  and  bears  no  simple  relationship  to  diameter  of  the  base. 
In  a longitudinal  direction  the  spine  is  usually  more  or  less  straight,  but  recurved  instances  are  also  known  (PI. 

2,  fig.  14).  In  transverse  section  the  spine  varies  between  circular  (e.g.  PI.  1,  figs  6 and  16)  to  distinctly  elongate 
(at  right  angles  to  the  antero-posterior  axis),  sometimes  with  a more  or  less  prominent  groove  on  one  margin. 
Most  typically  the  ornamentation  of  the  spine  consists  of  prominent  transverse  welts  that  impart  a ribbed 
appearance  (PI.  1,  figs  1,  2,  8,  11).  In  some  sclerites  a subsidiary  longitudinal  ornamentation  gives  a more 
nodular  appearance  to  the  spine  (PI.  2,  figs  3,  7,  8,  12),  while  in  some  spines  the  surface  bears  only  longitudinal 
lineations  (PI.  1,  figs  6,  10,  14).  In  this  last  case,  care  must  be  exercised  between  recognizing  an  original 
ornamentation  and  a spine  where  loss  of  the  outer  layers  (PI.  1,  figs  5 and  16)  has  affected  the  original  pattern 
and  imparted  a subdued  longitudinal  fibrosity  that  stems  from  exposure  of  the  wall  ultrastructure  (see  above). 

Discussion.  The  wide  morphological  variation  of  the  sclerites  has  been  interpreted  by  previous 
workers  as  representing  several  discrete  taxa,  which  have  been  distinguished  principally  upon  the 
criteria  of  spine  ornamentation  and  spine  length.  The  co-occurrence  of  morphs  ascribed  to  a number 
of  nominal  species  in  our  samples  and  the  continuity  of  variation  suggest  that  many,  if  not  all, 
these  sclerites  were  derived  from  a single  species,  here  recognized  on  grounds  of  priority  as 
Z.  longistriatus.  Specimens  with  spines  bearing  longitudinal  ribbing  have  been  attributed  by  previous 
workers  mostly  to  either  Z.  longistriatus  or  Z.  costatus , while  those  with  transverse  folds  have  been 


EXPLANATION  OF  PLATE  2 

Figs  1-  17.  Zhijinites  longistriatus  Qian,  1978.  1,  IGAS-BC-88-30091 . 2,  IGAS-BC-88-30092.  3,  IGAS-BC-88- 
30093.  4,  IGAS-BC-88-30094.  5,  IGAS-BC-88-30095,  ventral  surface.  6,  IGAS-BC-88-30096.  7,  IGAS-BC- 
88-30097.  8,  IGAS-BC-88-30098.  9,  IGAS-BC-88-30099.  10,  IGAS-BC-88-30100.  11,  IGAS-BC-88-30101 . 
12,  IGAS-BC-88-30102.  13,  IGAS-BC-88-30103.  14,  IGAS-BC-88-30104.  15,  IGAS-BC-88-30105.  16  and 
17.  IGAS-BC-88-30106;  16,  steinkern  of  spine  cavity;  17,  detail  of  steinkern  surface  showing  possible 
replication  of  wall  ultrastructure.  All  isolated  sclerites  from  Bed  37,  Maidiping  Member,  Hongchunping 
Formation  at  Maidiping  section,  Emei,  Sichuan,  China.  Magnifications  all  x 70,  except  Fig.  10  ( x 100),  Fig. 
14  ( x 35),  and  Fig.  17  ( x 700). 


PLATE 


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372 


PALAEONTOLOGY,  VOLUME  34 


placed  in  at  least  four  nominal  species  (Z.  annae  [nomen  nudum],  Z.  dictyformise  [nomen  nudum], 
Z.  minutus  and  Z.  triangularis).  The  synonymy  of  certain  other  species  with  Z.  longistriatus  remains 
less  certain.  Sclerites  with  more  or  less  smooth  spines  have  been  placed  mostly  in  Z.  lubricus , while 
sclerites  with  a slipper-like  base  and  very  elongate  spine  have  been  named  as  Parazhijinites 
guizhouensis  (sometimes  misspelt  quizhouensis). 

If  the  extensive  synonymies  proposed  above  are  accepted,  albeit  some  being  provisional,  then  it 
remains  to  be  decided  whether  an  individual  possessed  a corresponding  range  of  sclerite  types  or 
whether  the  variability  was  greater  between  animals,  with  any  one  individual  showing  a more 
restricted  degree  of  variation.  In  the  absence  of  either  articulated  individuals  or  fused  sclerites  (see 
below),  these  alternatives  remain  unresolved.  However,  as  a working  hypothesis  it  is  proposed  that 
morphological  variability  of  sclerites  in  any  one  individual  was  pronounced. 

If  it  was  possible  to  provide  an  adaptive  explanation  for  the  different  sclerite  types,  especially  with 
respect  to  spine  angle  and  spine  ornamentation,  then  one  might  hypothesize  further  about  the 
possible  distribution  of  the  sclerites  over  the  body.  In  discussing  cambroclaves  from  the  Lower 
Cambrian  of  Australia,  Bengtson  et  al.  (1990)  suggested  the  sclerites  were  used  to  grip  the 
sediment,  as  well  as  providing  a protective  function.  If  Zhijinites  had  a similar  mode  of  life,  then 
it  seems  possible  that  the  inclined  spines  served  to  provide  anchors  on  the  sediment  during 
locomotion.  It  is  suggested  further  that  the  transverse  corrugations  (PI.  1,  figs  1,  2,  11;  PI.  2,  figs 
1-3,  7-9,  12)  acted  as  a ratchet-like  device  to  increase  frictional  contact  with  the  sediment  grains. 
In  this  context  those  spines  with  a more  subdued  ornamentation  may  have  occupied  regions  of  the 
body  that  were  not  directly  involved  with  acting  as  anchors.  Concerning  the  varying  angles  the 
spines  make  with  the  basal  unit,  and  by  implication  the  surface  of  the  body,  this  could  be  linked  to 
local  configurations  of  the  epithelium. 

deiradoclavus  gen.  nov. 

Type  species.  Deiradoclavus  trigonus  gen.  et  sp.  nov. 

Derivation  of  generic  name.  From  the  Greek  deirados , meaning  ridge,  in  reference  to  prominent  ridges  on  both 
upper  and  lower  surfaces. 

Diagnosis.  Small  sclerites  with  variably  subcircular  outline,  occasionally  tending  to  quadrate. 
Dorsal  surface  bearing  tri-radiate  ridge,  delimiting  anterior  embayment  and  paired  postero-lateral 
embayments.  Anterior  embayment  bears  transversely  elongate  spine.  Ventral  surface  bearing  tri- 
radiate  ridge  in  opposite  orientation  to  that  of  dorsal  surface,  so  delimiting  posterior  embayment 
and  paired  antero-lateral  embayments. 


EXPLANATION  OF  PLATE  3 

Figs  1-13.  Zhijinites  longistriatus  Qian,  1978.  1-3,  1GAS-BC-88-30107;  1 and  2,  entire  sclerite;  3,  detail  of 
steinkerns  of  endolith  borings.  4-6,  IGAS-BC-88-30108;  4.  detail  of  steinkern  surface  showing  possible 
replication  of  wall  ultrastructure;  5,  steinkern  of  spine  cavity;  6,  detail  of  basal  region  of  steinkern.  7,  IGAS- 
BC-88-30109,  detail  of  steinkerns  of  endolith  borings  showing  blind  terminations  and  imprint  of  wall 
ultrastructure.  8,  IGAS-BC-88-301 10,  steinkern  and  partial  preservation  of  outer  wall.  9-1 1,  IGAS-BC-88- 
301 1 1 ; 9,  steinkern  of  spine  cavity;  10  and  1 1,  detail  of  steinkern  surface  showing  wall  ultrastructure  and 
endolith  borings,  note  variation  in  thickness.  12  and  13,  IGAS-BC-88-301 12;  12,  steinkern  of  spine  cavity; 
13.  detail  of  steinkern  surface  showing  wall  ultrastructure  and  endolith  borings.  All  isolated  sclerites  from 
Bed  36,  Maidiping  Member,  Hongchunping  Formation  at  Maidiping  section,  Emei,  Sichuan,  China. 
Magnifications:  x 70  (Figs  1,  2,  5,  9,  12);  x 500  (Fig.  3);  x 350  (Fig.  4);  x 140  (Figs  6,  8);  x 700  (Figs  7, 
10);  x 600  (Fig.  11);  x 1000  (Fig.  13). 


PLATE  3 


CONWAY  MORRIS  and  CHEN,  Zhijinites 


374 


PALAEONTOLOGY,  VOLUME  34 


Deiradoclavus  trigonus  gen.  et  sp.  nov. 

Plates  4 and  5;  Text-fig.  1 1 c 

Derivation  of  specific  name.  On  account  of  the  three-angled  ( gonia , Greek  for  angle)  arrangement  of  the  ridges. 
Diagnosis.  As  for  the  genus. 

Holotype.  IGAS-BC-88-301  14  (PI.  4,  fig.  2). 

Paratypes.  IGAS-BC-88-301 13,  30115-30136. 

Stratigraphic  horizon.  Guojiaba  Formation. 

Locality.  Xuanjiangping  section,  near  Xuanjiangping  village,  Kuanchuanpu,  Shaanxi. 

Taxonomic  comparisons.  With  one  possible  exception,  no  published  descriptions  of  cambroclaves 
can  be  closely  compared  to  Deiradoclavus.  The  exception  is  specimens  from  the  Yurtus  Formation 
of  Xinjiang,  referred  to  Wuschichites  polyedrus  by  Qian  and  Xiao  (1984,  pi.  3,  figs  12  and  13).  Here 
the  ventral  surface  appears  to  bear  a tri-radiate  ridge,  while  the  opposite  surface  is  described  as 
having  a tri-radiate  groove.  However,  while  the  tri-radiate  pattern  recalls  Deiradoclavus , in  this  new 
genus  both  sides  bear  ridges.  It  remains  conceivable  that  W.  polyedrus  should  be  transferred  to 
Deiradoclavus , but  synonymy  of  the  genera  would  not  be  necessary  because  of  the  distinctive  status 
of  the  type  species,  W.  minutus  (Qian  and  Xiao  1984,  pi.  1,  fig.  7;  pi.  3,  fig.  11).  Although  the  ventral 
surface  bears  a tri-radiate  ridge,  the  sclerites  of  W.  minutus  differ  from  Deiradoclavus  in  having  a 
prominent  posterior  notch  and  bulbous  anterior.  Indeed,  in  the  Xinjiang  material  similar  features 
are  also  visible  in  some  co-occurring  sclerites  of  Cambroclavus  (see  Qian  and  Xiao  1984,  pi.  3,  figs 
16,  18,  19);  these  supposedly  distinct  sclerites  may  represent  end-members  of  a single  cambroclavid 
species,  so  making  Wushichites  a junior  synonym  of  Cambroclavus  (see  Bengtson  et  at.  1990). 

Preservation.  In  common  with  other  cambroclaves,  the  sclerites  of  Deiradoclavus  (Pis  4 and  5)  appear  to  have 
had  their  originally  calcareous  walls  replaced  and/or  partly  coated  with  diagenetic  phosphate,  leaving  the 
interior  of  the  sclerite  hollow.  The  quality  of  replication  varies,  but  in  some  specimens  a fibrous  arrangement 
(e.g.  PI.  5,  fig.  2)  may  represent  an  original  ultrastructure  of  the  wall.  A similar  ultrastructure  has  been  noted 
in  both  cambroclaves  (Bengtson  et  at.  1990)  and  zhijinitids  (see  above). 

Description.  The  sclerites  may  be  sub-circular  in  outline  (PI.  4,  figs  1,  2,  7,  12),  but  the  range  of  variation  is  very 
considerable;  many  sclerites  approach  a quadrate  shape  (PI.  4,  figs  5,  6,  10;  PI.  5,  figs  1, 3,  8,  9,  12),  while  others 
are  relatively  elongate  (PI.  4,  figs  3 and  4)  or  more  irregular  in  shape  (PI.  4,  figs  12  and  13;  PI.  5,  fig.  2). 
Orientations  are  based  on  comparisons  with  other  cambroclaves  (Mambetov  in  Mambetov  and  Repina  1979; 
Bengtson  et  at.  1990;  see  also  discussion  above  of  zhijinitid  orientation);  in  particular  the  spine  is  taken  to  be 
anterior  and  to  arise  from  the  dorsal  surface. 

Notwithstanding  wide  morphological  variation,  the  dorsal  surface  of  most  sclerites  bears  a tri-radiate  ridge 
that  has  a point  of  divergence  located  slightly  anterior  to  the  mid-line  (PI.  4,  figs  1,  2,  10,  1 1,  13;  PI.  5,  figs  I 
and  3).  The  posterior  arm,  so  named  because  it  extends  to  that  margin,  is  relatively  broad  and  sometimes  flares 
towards  its  termination.  The  pair  of  anterior  arms  are  narrower,  and  usually  diverge  from  the  midline  at  an 
angle  of  about  60°.  Variation  in  development  of  these  ridges,  however,  is  considerable.  In  some  specimens  the 


EXPLANATION  OF  PLATE  4 

Figs  1-13.  Deiradoclavus  trigonus  gen.  et  sp.  nov.  1,  IGAS-BC-88-301 13.  2,  IGAS-BC-88-301 14,  holotype.  3 
and  4,  IGAS-BC-88-301  15.  5,  IGAS-BC-88-301 16.  6,  IGAS-BC-88-301 1 7.  7 and  8,  IGAS-BC-88-301 18.  9, 
IGAS-BC-88-301 19.  10,  IGAS-BC-88-30120.  11,  IGAS-BC-88-30121 . 12,  IGAS-BC-88-30122.  13,  IGAS- 
BC-88-301 23.  All  isolated  sclerites,  dorsal  surface,  from  the  Guojiaba  Formation  at  Xuanjiangping  section 
near  Kuanchuanpu,  Shaanxi,  China.  Magnifications  all  x 90. 


PLATE  4 


CONWAY  MORRIS  and  CHEN,  Deiradoclavus 


376 


PALAEONTOLOGY,  VOLUME  34 


posterior  arm  is  very  broad  and  may  bear  either  a median  furrow  (PI.  4,  figs  3 and  4;  PI.  5,  fig.  3)  or  a series 
of  grooves  (PI.  4,  figs  10  and  12)  that  are  irregularly  disposed  and  extend  from  the  posterior  margin  by  variable 
amounts.  Similarly,  the  strength  of  development  of  the  anterior  arms  varies,  but  usually  at  least  some  trace  is 
perceptible  (PL  4,  fig.  5).  The  tri-radiate  nature  of  the  ridge  defines  three  gently  concave  depressions,  termed 
here  embayments,  that  open  towards  the  anterior  margin  (1)  and  postero-lateral  margins  (2,  3)  respectively. 
The  anterior  embayment  houses  a narrow,  transversely  elongate  ridge  (PI.  4;  PI.  5.  figs  1-3)  whose  distal 
termination  is  not  known  owing  to  incomplete  phosphatization.  This  structure  is  referred  to  as  the  anterior 
spine,  a term  that,  while  not  precisely  descriptive,  emphasizes  its  presumed  homology  with  comparable 
structures  in  other  cambroclaves. 

The  ventral  surface  also  bears  a tri-radiate  ridge  (PI.  5,  figs  4-15),  although  its  sense  of  branching  is  reversed 
(i.e.  rotated  through  180°),  in  comparison  to  the  Y-shaped  ridge  on  the  upper  surface.  Accordingly,  an  anterior 
ridge  diverges  from  the  paired  postero-lateral  ridges,  with  the  point  of  divergence  located  more  or  less  at  the 
mid-point  of  the  sclerite.  Although  the  anterior  arm  is  sometimes  a single  crest,  more  often  it  forms  a pair  of 
ridges  that  are  separated  by  a median  depression  (PI.  5,  figs  4-6,  14).  On  occasions  this  furrow  is  bisected  by 
yet  another  ridge  (PI.  5,  figs  10  and  1 1).  The  postero-lateral  arms  are  usually  simple  and  diverge  at  an  angle 
that  is  controlled  by  the  shape  of  the  sclerite  and  varies  from  about  125°.  in  sclerites  which  are  broader  than 
long  (PI.  5,  fig.  5),  to  about  100°  where  the  sclerite  is  more  quadrate  (PI.  5,  fig  12).  The  embayments  defined 
by  the  tri-radiate  ridge  on  the  ventral  surface  are  broadly  concave.  This  is  particularly  noticeable  in  the 
posterior  embayment  (PL  5,  figs  4,  11,  13)  that  is  flanked  by  the  postero-lateral  arms.  The  anterior  embayments 
occasionally  bear  subsidiary  ridges  (PI.  5,  figs  10  and  I 1)  and  may  also  be  traversed  by  subdued  grooves  (PI. 
5,  fig.  15). 

Palaeoecology.  Evidence  from  fused  sclerites  (Mambetov  in  Mambetov  and  Repina  1979;  Bengtson 
et  al.  1990),  articulatory  facets,  and  outline  shapes  that  allow  for  mutual  accommodation  and 
interlocking  in  Cambroclavus  all  suggest  that  the  animal  was  originally  coated  by  a scleritome  (Text- 
fig.  1 1 b).  Fused  sclerites  have  not  been  recognized  in  Deiradoclavus , but  the  paired  postero-lateral 
embayments  on  the  dorsal  surface  are  interpreted  as  acting  as  points  of  articulation  with  the 
anterior  corners  of  the  two  adjacent  sclerites  (Text-fig.  1 1 c).  In  this  schema  the  anterior  depression, 
defined  by  the  two  ridges  on  the  ventral  surface  of  most  sclerites,  would  act  to  accommodate  the 
posterior  arm  on  the  dorsal  surface  of  the  next  sclerite  to  the  anterior.  Such  an  interlocking  pattern 
would  have  provided  a more  or  less  continuous  cover  of  the  body,  providing  an  effective  armour, 
especially  with  the  added  complement  of  spines  projecting  from  the  anterior  of  each  sclerite. 

Relationships.  Deiradoclavus  trigonus  is  regarded  as  a cambroclave  because  of  its  broad  similarity  to 
Cambroclavus  spp,  including  an  anterior  spine  and  median  ridge  flanked  by  embayments.  Indeed, 
rare  sclerites  approach  quite  closely  Cambroclavus  (PI.  4,  figs  3 and  4),  but  the  great  majority  differ 
in  three  principal  ways:  they  are  more  or  less  sub-circular  to  quadrate  rather  than  elongate,  they 
bear  prominent  tri-radiate  ridges  on  both  dorsal  and  ventral  surfaces,  and  the  anterior  spine  is 
elongately  transverse  rather  than  a simple  conical  extension. 

Mention  was  made  above  concerning  possible  comparisons  between  Deiradoclavus  and 
Wushichites , especially  W.  polyedrus  (Qian  and  Xiao  1984).  With  the  available  illustrations  and  lack 
of  information  on  scleritome  variability  of  co-occurring  cambroclaves,  objective  comparisons  are 
not  easy,  and  the  possible  inclusion  of  W.  polyedrus  in  Deiradoclavus  must  be  regarded  as  tentative. 
Although  Zhijinites  has  a more  or  less  circular  base,  it  is  surmounted  by  an  eccentrically  located 
spine  and  is  less  similar  to  Deiradoclavus  than  Cambroclavus.  Indeed  the  transition  between 


EXPLANATION  OF  PLATE  5 

Figs  1-15.  Deiradoclavus  trigonus  gen.  et  sp.  nov.  1,  IGAS-BC-88-30124.  2,  IGAS-BC-88-30125.  3,  IGAS-BC- 
88-30126.  4 and  5,  IGAS-BC-88-301 27.  6,  IGAS-BC-88-30128.  7,  IGAS-BC-88-30129.  8,  IGAS-BC-88- 
30130.  9,  IGAS-BC-88-301 3 1 . 10  and  11,  IGAS-BC-88-30132.  12,  IGAS-BC-88-30133.  13,  IGAS-BC-88- 
30134.  14,  IGAS-BC-88-301 35.  15,  IGAS-BC-88-30136.  All  isolated  sclerites,  dorsal  (Figs  1-3)  and  ventral 
(Figs  4-15)  surfaces,  from  Guojiaba  Formation  at  Xuanjiangping  section  near  Kuanchuanpu,  Shaanxi, 
China.  Magnifications  all  x 90. 


PLATE  5 


CONWAY  MORRIS  and  CHEN,  Deiradoclavus 


378 


PALAEONTOLOGY,  VOLUME  34 


Zhijinites  and  Cambroclavus  may  be  envisaged  as  arising  from  an  extension  of  the  posterior  region 
and  the  development  of  a closely  interlocking  scleritome.  Deiradoclavus  would  be  derived  in  turn 
from  a cambroclavid  by  decreasing  the  length  to  width  ratio,  which  would  also  explain  the 
transversely  elongate  spine. 

Genus  deltaclavus  gen.  nov. 

Type  species.  Deltaclavus  graneus  gen.  et  sp.  nov. 

Derivation  of  the  generic  name.  On  account  of  the  triangular  or  delta  shape  of  the  sclerites. 

Diagnosis.  Sclerites  with  broad  anterior  edge,  and  lateral  edges  converging  to  posterior  point, 
imparting  triangular  outline.  Dorsal  surface  with  longitudinal  median  ridge,  terminating  anteriorly 
in  subdued  spine.  Lateral  portions  of  dorsal  surface  gently  concave.  Ventral  surface  with  prominent 
anterior  facet,  sometimes  bounded  by  subdued  ridges.  Remainder  of  ventral  surface  gently  rounded 
and  more  or  less  smooth. 


Deltaclavus  graneus  sp.  nov. 

Plates  6 and  7;  Text-figs  8,  9,  11  d 

Derivation  of  specific  name.  From  the  Latin  graneus , in  reference  to  the  seed  or  pip-like  appearance  of  the 
individual  sclerites. 

Diagnosis.  As  for  the  genus. 

Holotype.  IGAS-BC-88-30180  (Text-fig.  9 a-c). 

Paratypes.  IGAS-BC-88-301 54-301 79,  30181. 

Stratigraphic  horizon.  Lower  Shuijingtuo  Formation,  Lower  Cambrian. 

Locality.  Taishanmiao  section,  near  the  village  of  Taishanmiao,  Hubei. 

Preservation.  The  style  of  preservation,  with  secondary  phosphatization  of  the  sclerite  wall  and  limited  infill 
of  the  central  cavity,  is  comparable  to  that  described  above  for  the  type  material  of  Deiradoclavus  trigonus  gen. 
et  sp.  nov. 

Description.  The  majority  of  specimens  are  isolated  sclerites  (Pis  6 and  7),  but  rare  examples  of  fused 
assemblages  (Text-figs  8 and  9)  are  of  considerable  importance  for  partial  scleritome  reconstruction.  In 
comparison  with  other  cambroclave  species,  isolated  sclerites  are  relatively  small,  typically  about  350-400  pm 
in  length.  In  dorso-ventral  view  the  sclerites  have  a triangular  shape,  defined  by  a gently  convex  arcuate 
anterior  margin  and  lateral  margins  that  converge  posteriorly  to  a pointed  termination  (PI.  6,  figs  1,  4,  5,  7, 
11,  14;  PI.  7,  figs  1,  5,  6,  8,  1 1.  13).  The  outline  shape  varies  from  relatively  narrow  (PI.  6,  fig.  5)  to  rarer  broader 
sclerites  (PI.  6,  fig.  13;  PI.  7,  figs  3 and  8).  In  lateral  view,  the  sclerite  is  highest  at  the  anterior,  and  declines 
posteriorly  (PI.  6.  figs  3,  6,  12,  13;  PI.  7,  figs  2 and  3).  The  dorsal  surface  bears  a prominent  median  ridge  that 
at  the  anterior  end  expands  into  a broader  area,  surmounted  by  a knobbly  spine  (PI.  6,  figs  1,8,  14;  PI.  7,  figs 
1 and  4).  In  narrower  sclerites  this  latter  structure  is  more  or  less  circular,  but  in  broader  ones  it  is  transversely 


EXPLANATION  OF  PLATE  6 

Figs  I -15.  Deltaclavus  graneus  gen.  et  sp.  nov.  1,  IGAS-BC-88-301 54.  2-4,  IGAS-BC-88-301 55.  5 and  6,  IGAS- 
BC-88-301 56.  7,  IGAS-BG88-30157.  8,  IGAS-BC-88-301 58.  9,  IGAS-BC-88-301 59.  10,  IGAS-BC-88- 
30160.  11  and  12,  IGAS-BC-88-30161 . 13,  IGAS-BC-88-30162.  14  and  15,  IGAS-BC-88-30163.  All  isolated 
sclerites,  dorsal  surface,  from  the  Shuijingtou  Formation  at  the  Taishanmiao  section,  near  Taishanmiao, 
Hubei,  China.  Magnifications  all  x 150. 


PLATE  6 


CONWAY  MORRIS  and  CHEN,  Deltaclavus 


380 


PALAEONTOLOGY,  VOLUME  34 


expanded.  Although  this  projection  is  more  nodose  than  spinose,  the  term  spine  is  employed  here  (as  with 
Deiradoclavus  trigonus  gen.  et  sp.  nov.,  see  above)  because  of  its  inferred  homology  with  other  cambroclavid 
spines.  The  lateral  regions  on  either  side  of  the  dorsal  ridge  are  gently  concave.  Apart  from  occasional  sclerites 
with  subdued  ridge-like  developments,  the  dorsal  surface  is  more  or  less  smooth.  The  ventral  surface  is  also 
more  or  less  smooth,  and  gently  rounded,  except  at  the  anterior  end  where  there  is  a distinct  concave  facet  that 
may  be  flanked  by  subdued  ridges  (PI.  7,  figs  6-14). 

Fused  assemblages  of  sclerites  occur  as  two  variants.  The  first  type  consists  of  a longitudinal  file  of  three, 
four  or  five  sclerites  with  the  posterior  dorsal  surface  in  juxtaposition  to  the  ventral  facet  of  the  anterior  region 
(Text-figs  8 a,  b and  9 a-c).  The  second  variant  consists  of  fused  rows,  that  also  articulate  via  their  ventral 
surface  with  another  row  such  that  the  posterior  ends  of  opposite  sclerites  touch  one  another.  Two  such 
examples  of  sclerite  rows  running  ‘back  to  back’  have  been  recognized.  One  consists  of  a single  file  (Text-fig. 
8 c-/')  on  each  side,  and  the  other  of  a double  file  (Text-fig.  9 d-h).  In  the  latter  case  the  interlocking  of  adjacent 
sclerites  of  each  file  on  either  side  is  seen  to  alternate.  The  sclerites  of  the  second  type  of  fused  assemblage  are 
broader,  with  the  posterior  termination  more  distinctly  demarcated  from  the  remainder  of  the  sclerite  whose 
lateral  edges  tend  to  be  wing-like. 

Remarks.  The  significance  of  the  fused  assemblages  of  D.  graneus  in  scleritome  reconstruction  of 
cambroclaves  is  discussed  below.  Specimens  of  sclerites  comparable  to  Deltaclavus  appear  not  to 
have  been  recognized  previously,  although  in  this  context  attention  should  be  drawn  to 
problematical  fossils  from  the  Lower  Tal  Formation  of  Uttar  Pradesh,  India.  In  particular  a 
specimen  illustrated  by  Bhatt  et  al.  (1983,  pi.  2,  fig.  2)  seems  to  be  comparable  to  D.  graneus , and 
in  any  event  their  attribution  to  Sachites  seems  unlikely.  It  should  be  noted  that  the  stratigraphic 
position  of  the  Indian  occurrence  at  present  is  correlated  with  substantially  older  sequences  (Brasier 
and  Singh  1987)  than  the  Shuijingtuo  Formation  from  which  D.  graneus  derives. 

Family  paracarinachitidae  Qian,  1984 

Diagnosis  (emended  from  Qian  1984).  Sclerites  concavo-convex,  more  or  less  bilaterally 
symmetrical.  Elongate  spatula-like  axis,  tapering  to  blunt  apex,  usually  bearing  median  row  of 
spines  but  sometimes  smooth.  Lateral  flanges,  wing-like,  sometimes  present,  smooth  except  for 
occasional  furrows.  Incremental  growth.  Calcareous  composition. 

Discussion.  Qian  and  Bengtson  (1989,  p.  48)  only  referred  to  this  family  in  passing,  but  noted  that 
Paracarinachites  might  be  related  to  Scoponodus  Jiang,  1982.  They  drew  attention  to  possible 
similarities  to  Ernogia  Jiang,  1982,  and  as  noted  below  it  may  transpire  that  both  these  genera 
should  be  accommodated  in  Paracarinachitidae. 

paracarinachites  Qian  and  Jiang,  1982 
Type  species.  Paracarinachites  sinensis  Qian  and  Jiang,  1982. 

Diagnosis.  See  Qian  and  Bengtson  (1989,  p.  49). 


explanation  of  plate  7 

Figs  I -15.  Deltaclavus  graneus  gen.  et  sp.  nov.  1,  IGAS-BC-88-30164.  2,  IGAS-BC-88-30165.  3,  IGAS-BC-88- 
30166.  4,  IGAS-BC-88-30167.  5,  IGAS-BC-88-30168.  6,  IGAS-BC-88-30169.  7,  IGAS-BC-88-30170. 
8,  IGAS-BC-88-301 7 1 . 9,  IGAS-BC-88-30172.  10  and  11,  IGAS-BC-88-30173.  12,  IGAS-BC-88-30174.  13 
and  14,  IGAS-BC-88-301 75.  15,  IGAS-BC-88-301 76.  All  isolated  sclerites,  dorsal  (Figs  1^4)  and  ventral 
(Figs  5-15)  surfaces,  from  the  Shuijingtou  Formation  at  the  Taishanmiao  section,  near  Taishanmiao, 
Hubei,  China.  Magnifications  all  x 150. 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  8.  Deltaclavus  graneus  gen.  et  sp.  nov.  a,  IGAS-BC-88-30177.  b , IGAS-BC-88-30178.  c-f,  IGAS-BC- 
88-30179;  c and  d , ‘lower’  surface;  e , lateral  view;  f ‘upper’  surface.  All  articulated  series  of  sclerites,  from 
the  Shuijingtou  Formation  at  the  Taishanmiao  section,  near  Taishanmiao,  Hubei,  China.  Magnifications;  a , 

x 150;  b-f. i x 100. 


Discussion.  An  extensive  discussion  of  Paracarinachites  (Junior  synonyms  include  Yangtzechiton  Yu 
1984a,  Luyanhaochiton  Yu  1984u)  is  provided  by  Qian  and  Bengtson  (1989)  who  recognised  four 
species  ( P . sinensis , P.  columellatus,  P.  parcibolicus  and  P.  spinus;  whether  the  species  erected  by  He 
and  Xie  (1989,  pi.  1,  figs  13-15)  as  Paracarinachites  bispinosus  can  be  included  in  this  genus  seems 
to  be  more  questionable).  In  each  case  the  available  specimens  consist  of  elongate,  bilaterally 
symmetrical  sclerites  composed  of  a series  of  growth  increments  that  are  usually  marked  by  denticles 
arising  from  the  outer  side.  In  P.  spinus  the  incremental  nature  of  the  sclerites  is  particularly  clear 
on  account  of  the  prominent  divisions  that  convey  the  impression  of  units  overlapping  in  an 
abapical  direction  (see  Qian  and  Bengtson  1989,  fig.  29;  He  and  Xie  1989,  pi.  1,  figs  17-19,  21).  Qian 
and  Bengtson  (1989)  emphasized,  however,  that  the  sclerite  was  a single  unit,  citing  evidence  of 
lateral  fusion  on  the  outer  side  and  a seamless  appearance  on  the  lower  side  that  they  interpreted 
as  resulting  from  the  adpression  of  successive  lamellae  during  growth. 

Here  we  report  also  zhijinitid-like  denticles  that  are  strikingly  similar  to  the  increments  that  go 
to  make  up  the  sclerites  of  P.  spinus  as  reported  by  Qian  and  Bengtson  (1989;  see  also  He  and  Xie 


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383 


text-fig.  9.  Deltaclavus  graneus  gen.  et  sp.  nov.  a-c,  IGAS-BC-88-30180,  holotype;  a,  lateral  view;  b , oblique 
view;  c,  dorsal  view,  d-h,  IGAS-BC-88-30181 ; d,f,  ‘lower’  surface;  e,  g , ‘upper’  surface;  h,  detail  of ‘upper’ 
surface.  All  articulated  series  of  sclerites,  from  the  Shuijingtou  Formation  at  the  Taishanmiao  section,  near 
Taishanmiao,  Hubei,  China.  Magnifications:  a-c,  x 100;  d-g,  x75;  h,  x 150. 


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PALAEONTOLOGY,  VOLUME  34 


1989).  The  recognition  of  separate  elements  need  not  negate  Qian  and  Bengtson’s  interpretation  of 
an  incremental  assemblage  and  the  significance  of  these  observations  on  the  affinities  of 
Paracarinachites  are  returned  to  below. 


Paracarinachites  spinus  (Yu,  1984a) 

Plate  8;  Text-fig.  10 

Diagnosis.  For  isolated  sclerites:  base  semi-circular  to  oval  with  concave  ventral  surface,  dorsal 
surface  bearing  prominent  curved  spine,  inserted  towards  anterior  side.  Dorsal  surface  variously 
ornamented,  including  concentric  ridge  and  towards  margin  radial  ridges.  For  fused  sclerites,  see 
Qian  and  Bengtson  (1989). 

Holotype.  ASN  84135  (see  Yu  1984a,  pi.  1,  figs  8 and  9). 

Material  illustrated  here.  IGAS-BC-88-301 37-301 53. 

Remarks.  A synonymy  and  discussion  of  the  taxonomic  status  of  these  sclerites  are  provided  by 
Qian  and  Bengtson  (1989),  to  which  may  be  added  illustrations  of  fused  and  isolated  sclerites  from 
Meishucun  by  Fie  and  Xie  (1989,  pi.  1,  figs  16-22)  who  continued  to  refer  to  it  as  Yangtzechiton 
elongatus.  In  addition,  it  seems  conceivable  that  one  specimen  identified  as  Zhijinites  sp.  from  the 
top  of  the  Zhongyicun  Member  at  Meishucun  (Jiang  1980,  pi.  4,  fig.  17;  the  other  specimen 
illustrated  in  pi.  4,  fig.  18  may  not  be  a cambroclave)  is  an  isolated  sclerite  comparable  to  material 
described  here.  The  status  of  Z.  undulatus  in  this  context  is  more  uncertain.  One  sclerite,  from  near 
Leibo,  Sichuan  (Jiang  1982,  pi.  17,  fig.  12,  12a)  might  be  tentatively  referred  to  P.  spinus.  Flowever, 
the  other  specimens  illustrated  by  Jiang  (1982,  pi.  17,  fig.  1 1),  from  the  Dahai  section  near  Huize, 
are  assigned  provisionally  to  Z.  longistriatus  (see  above). 

Stratigraphic  horizon.  Bed  7,  Zhongyicun  Member,  Yuhucun  Formation,  Meishucun  Stage,  Lower  Cambrian. 
Locality.  Xiaowaitoushan  section,  Kunyang  Phosphorite  Mine,  Meishucun,  Yunnan. 

Preservation.  The  sclerites  are  replaced  with  massive  phosphate,  which  in  etched  and  polished  material  is  seen 
to  replace  not  only  the  walls  but  also  the  internal  cavity. 

Description.  The  sclerites  are  divisible  into  a sub-circular  to  oval  base  and  elongate  spine  (PI.  8;  Text-fig.  10). 
The  former  unit  has  a concave  lower  surface,  that  is  more  or  less  smooth  (PI.  8,  fig.  6;  Text-fig.  10/,  g).  The 
opposite  surface  of  the  base  usually  bears  subdued  ornamentation,  which  may  include  a series  of  concentric 
ridges  (PI.  8,  figs  2,  3,  17;  Text-fig.  lOe)  or  more  occasionally  a more  pronounced  furrow  (PI.  8,  figs  14  and 
15).  A finer-scale  ornamentation  of  radial  ridges,  that  tends  to  be  most  accentuated  near  the  margins,  is 
characteristic  (PI.  8,  figs  1,  4,  5,  7,  8,  10,  15,  17;  Text-fig.  lOe).  The  margins  themselves  are  often  more  or  less 
smooth,  but  on  occasion  they  show  indentations  or  more  developed  scallops,  especially  on  the  posterior 
margin. 

The  spine  is  conspicuous,  usually  stout,  and  terminates  in  a simple  point.  Its  insertion  is  eccentric,  towards 
the  presumed  anterior  side  and  it  may  even  arise  from  the  anterior  margin  (Text-fig.  10  c).  The  degree  of 
curvature  is  variable,  and  although  in  most  sclerites  the  spine  inclines  towards  the  posterior  mid-point,  in  some 
specimens  the  spine  is  recurved  to  one  side  (Text-fig.  106). 

Discussion.  If  a series  of  these  sclerites  was  aligned  in  an  imbricated  file  parallel  to  their  antero- 
posterior axes  they  would  appear  to  be  almost  indistinguishable  from  the  fused  assemblages 
described  by  earlier  workers  (Qian  and  Bengtson  1989;  see  also  Yu  1984a,  b,  1989).  Qian  and 
Bengtson  ( 1989)  presented  evidence  for  the  fused  assemblages  to  be  primary  rather  than  diagenetic, 
although  in  either  case  juxtaposition  of  the  sclerites  presumably  reflects  a life  orientation.  Unless  the 
fused  assemblages  are  teratological,  then  it  seems  likely  that  they  derived  from  one  or  more  specific 


CONWAY  MORRIS  AND  CHEN  : CAMBRIAN  PROBLEMATICA 


385 


text-fig.  10.  Paracarinachites  spinus  (Yu,  1984).  a,  IGAS-BC-88-30148.  b and  c,  IGAS-BC-88-30149.  d,  IGAS- 
BC-88-301 50.  e,  IGAS-BC-88-301 51 . /,  IGAS-BC-88-301 52.  g,  IGAS-BC-88-30153.  All  isolated  sclerites, 
dorsal  (a-e)  and  ventral  (/  and  g)  surfaces,  from  Bed  7,  Zhongyicun  Member,  Yuhucun  Formation  at 
Xiaowaitoushan  section,  Kunyang  Phosphorite  Mine,  Meishucun,  Yunnan,  China.  Magnifications  all  x90. 

regions  of  the  body,  while  the  isolated  sclerites  described  here  (see  also  He  and  Xie  1989)  come  from 
other  regions. 

Apart  from  occurrences  of  fused  assemblage  of  Paracarinachites  spinus , the  sclerites  of  this  taxon 
differ  from  those  of  Zhijinites  longistriatus  in  several  respects.  These  include  relative  proportions  of 
base  to  spine,  and  ornamentation  of  spine.  However,  as  noted  below,  P.  spinus  may  be  considerably 
more  closely  related  to  the  zhijinitids  (see  also  Qian  and  Bengtson  1989,  p.  56)  than  other  species 
of  Paracarinachites  (including  the  type  species,  P.  sinensis ),  so  that  inclusion  in  the  Zhi jinitidae  may 
be  a preferred  option.  If  this  transpires  to  be  the  case  then  the  similarity  between  the  serial  row  of 
fused  sclerites  in  P.  spinus  and  the  spinose  row  in  other  paracarinachitids  would  be  convergent. 

Protopterygotheca  leshanensis  Chen  in  Qian,  Chen  and  Chen,  1979 
Plate  9;  Text-figs  12  and  13 

1977  Protopterygotheca  leshanensis  (nomen  nudum)  Zhong  [Chen],  p.  122,  pi.  3,  figs  16-18. 

1979  Protopterygotheca  leshanensis  Chen  in  Qian  et  a /.,  pp.  221-222,  pi.  3,  figs  18  and  19. 

Discussion.  Although  fossils  attributable  to  this  taxon  were  illustrated  by  Zhong  [Chen]  (1977),  the 
formalities  necessary  for  a proper  description  were  not  met  until  1979  (Qian  et  al.  1979)  when 


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PALAEONTOLOGY,  VOLUME  34 


Protopterygotheca  leshanensis  became  a valid  taxon.  As  noted  below  several  species  of  Solenotia 
may  also  be  compared  to  Protopterygotheca. 

Diagnosis.  Sclerite  broadly  trilobate  with  elongate  central  axis  flanked  by  marginal  flanges.  Strongly 
convex  axis,  apex  bluntly  pointed  and  increasing  width  abapically.  Axis  usually  smooth,  but 
occasionally  with  transverse  furrows,  and  more  rarely  subdued  denticles  in  median  row.  Lateral 
zones  slope  from  axis,  outline  more  or  less  triangular.  Lateral  zones  usually  smooth,  but  may  bear 
transverse  or  more  occasionally  longitudinal  folds.  Sclerite  edges  marked  by  doublure,  sometimes 
showing  growth  increments.  Interior  of  sclerite  usually  smooth,  occasionally  irregular  furrows  on 
marginal  zone. 

Holotype.  ASN  51764. 

Paratypes.  1G  AS-  BC-88-30 1 83-30 1 98. 

Stratigraphic  horizon.  Beds  36  and  37,  Maidiping  Member,  Hongchunping  Formation,  Meishucun  Stage, 
Lower  Cambrian  (see  also  Zhong  [Chen]  1977;  note  that  the  holotype  is  recorded  as  coming  from  the 
Tianzhushan  section,  near  Yichang,  Hubei  (see  Qian  et  al.  1979,  p.  222)). 

Locality.  Maidiping  section,  Emei,  Sichuan. 

Preservation.  The  sclerites  are  preserved  as  fine-grained  phosphate,  densely  interwoven  with  abundant 
vermiform  tubules  (PI.  9,  fig.  15).  This  texture  appears  to  have  resulted  by  diagenetic  phosphatization,  possibly 
of  an  originally  calcareous  skeleton.  The  tubules  are  believed  to  represent  cndolithic  organisms,  possibly  algae, 
that  infested  disassociated  sclerites  after  the  death  of  the  animal. 

Description.  Sclerites  show  wide  morphological  variability  about  a basic  deltoid  shape  that  consists  of  a central 
axis  flanked  by  marginal  zones  (PL  9,  figs  1,  2,  4-14;  Text-fig.  12a,  6,  d , g,  h).  Sclerites  appear  to  have  been 
more  or  less  bilaterally  symmetrical,  although  differences  in  outline  and  furrow  development  on  each  lateral 
zone  leads  to  slight  departures  in  symmetry.  The  sclerites  are  orientated  with  respect  to  the  beak-like  apex  of 
the  central  axis,  arbitrarily  regarded  as  anterior,  and  the  convex  dorsal  surface  being  distinguished  from  the 
corresponding  concave  ventral  surface. 

The  central  axis  is  strongly  convex.  Its  angle  of  cross-section  may  exceed  180°,  so  that  the  furrow  between 
the  axis  and  lateral  flanges  forms  a recessed  overhang  (Text-fig.  12g).  The  axis  tapers  anteriorly  to  a blunt  apex, 
while  its  expansion  in  the  opposite  direction  is  relatively  even  (PL  9,  figs  1, 5-8,  1 1 ; Text-fig.  12/?).  The  posterior 
edge  may  be  largely  occupied  by  this  expanded  central  axis,  which  tends  to  have  a more  flattened  convexity 
than  adapically.  In  longitudinal  section  the  axis  tends  to  be  gently  arcuate  about  a mid-point,  with  both 
anterior  and  posterior  sections  curving  downwards  (PL  9,  fig.  4;  Text-fig.  12 d.  /).  In  most  sclerites  the  central 
axis  is  more  or  less  smooth.  More  occasionally,  especially  when  the  axis  is  relatively  broad,  it  is  traversed  by 
furrows  (PI.  9,  fig.  13).  These  are  relatively  subdued,  and  while  some  are  irregularly  developed  others  can  be 
traced  across  the  entire  axis  and  on  the  midline  form  an  anterior  cuspate  extension.  In  such  cases  the  midline 
also  bears  an  associated  series  of  subdued  tubercles  inclined  abapically  (Text-fig.  12e,/). 

The  extent  of  the  lateral  flanges  appears  to  be  controlled  in  part  by  preservation,  but  also  reflects  original 
variation.  The  angle  the  flanges  make  with  the  axial  zone  varies  widely  so  they  may  be  more  or  less  flat  or 
contribute  significantly  to  the  overall  convexity  of  the  sclerite.  Along  the  anterior  edges  the  lateral  extension 


EXPLANATION  OF  PLATE  8 

Figs  I -17.  Paracarinachites  spinus  (Yu  1984).  I,  IGAS-BC-88-30137.  2 and  3,  IGAS-BC-88-30138.  4 and  5, 
IGAS-BC-88-30139.  6,  IGAS-BC-88-30140.  7 and  8,  IGAS-BC-88-30141 . 9 and  10,  IGAS-BC-88-30142.  1 1 
and  12,  IGAS-BC-88-30143.  13,  IGAS-BC-88-30144.  14  and  15,  IGAS-BC-88-30145.  16,  IGAS-BC-88- 
30146.  17,  IGAS-BC-88-30147.  All  isolated  sclerites,  dorsal  (Figs  1-5,  7-17),  and  ventral  (Fig.  6)  surfaces, 
from  Bed  7,  Zhongyicun  Member,  Yuhucun  Formation  at  Xiaowaitoushan  section,  Kunyang  Phosphorite 
Mine,  Meishucun,  Yunnan,  China.  Magnifications  all  x90. 


PLATE  8 


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text-fig.  11.  Hypothetical  reconstructions  of  partial  portions  of  the  scleritome  of  (a)  Zhijinites  longistriatus ; 
(b)  Cambroclavus  absonus',  ( c ) Deiradoclavus  trigonus',  (d ) Deltaclavus  graneus.  Text-figure  lb  is  based  on 

Bengtson  et  al.  (1990,  fig.  70). 


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389 


text-fig.  12.  Protopterygotheca  leshanensis  Chen  in  Qian  et  al .,  1979.  a and  b,  IGAS-BC-88-30192;  a,  dorsal 
view;  b , oblique  view,  c,  IGAS-BC-88-30193,  ventral  view,  d , IGAS-BC-88-30194.  lateral  view;  e and/,  IGAS- 
BC-88-30195;  e , dorsal  view;  / oblique  view,  g-i,  IGAS-BC-88-30196;  g,  posterior  view;  h,  dorsal  view;  /, 
lateral  view.  / 1GAS-BC-88-30197,  ventral  view  with  internal  furrows,  k , IGAS-BC-88-30198,  fused  specimen. 
Isolated  sclerites  from  Bed  37  (a-c)  and  Bed  36  (d-k),  Maidiping  Member,  Hongchunping  Formation  at 
Maidiping  section,  Emei,  Sichuan,  China.  Magnifications:  a-d , x30;  e,  f,  h-k,  x60;  g,  x 100. 


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PALAEONTOLOGY,  VOLUME  34 


of  the  flanges  may  be  more  or  less  at  right  angles  to  the  central  axis  (PI.  9,  figs  6 and  14;  Text-fig.  12  a)  or  be 
inclined  posteriorly  so  that  the  maximum  width  is  nearer  the  transverse  mid-line  (PI.  9,  figs  7 and  1 1 ; Text-fig. 
12/;).  The  flanges,  therefore,  form  wing-like  extensions  of  widely  variable  shape  according  to  the  angles  of 
insertion  towards  the  anterior  and  posterior  ends  of  the  central  axis. 

Each  lateral  flange  of  a sclerite  is  similar,  but  minor  differences  can  exist  by  the  asymmetrical  development 
of  furrows  on  one  flange  (PI.  9,  figs  6,  8,  9,  II,  12;  Text-fig.  12/;).  Typically  these  furrows  are  transverse,  and 
if  they  extend  to  the  sclerite  margin  may  disrupt  the  outline.  The  furrows  grade  from  fairly  open  folds  to  more 
deeply  incised  structures.  Often  the  folds  are  grouped,  sometimes  radiating  outwards.  In  addition,  a few  flanges 
bear  longitudinal  folds. 

In  the  majority  of  sclerites  the  margins  are  simple,  but  this  may  be  an  artefact  of  preservation  because  in 
some  specimens  the  sclerite  edge  forms  a simple  doublure  (Text-fig.  12c).  However  preserved,  the  edge  seldom 
shows  internal  structure,  although  rarely  incremental  units  are  visible  (PI.  9,  figs  4 and  10).  The  internal  surface 
of  the  sclerite  is  normally  smooth  (PI.  9,  fig.  3),  but  on  occasion  a series  of  transverse  furrows  that  increase  in 
strength  towards  the  margin  (Text-fig.  \2j)  have  been  noted. 

With  one  exception,  the  sclerites  occur  isolated.  In  one  individual,  however,  part  of  a central  axis  (and  a 
specimen  of  Zhijinites  longistriatus)  appears  to  have  fused  to  another  sclerite,  the  respective  axes  pointing  in 
opposite  directions  (Text-fig.  12 k).  It  is  argued  below  that  the  sclerites  may  have  formed  an  imbricated  series, 
but  this  particular  association  seems  to  be  one  of  post-mortem  fusion  during  phosphatization. 

Discussion.  In  isolation  the  central  axis  of  these  sclerites  strongly  resembles  in  overall  shape  and 
dimensions  specimens  of  Paracarinachites  sinensis  (Qian  and  Bengtson  1989).  In  addition  Kerber 
(1988)  noted  traces  of  lateral  extensions  in  his  paracarinachitid  material  from  the  Montagne  Noire, 
France,  but  it  is  difficult  to  decide  whether  the  absence  from  the  Chinese  material  is  preservational 
or  an  original  difference  that  justifies  taxonomic  separation  between  it  and  the  French  examples 
(Qian  and  Bengtson  1989).  While  the  specimens  described  here  from  Maidiping  can  be  referred  to 
the  paracarinachitids,  the  precise  taxonomic  status  is  somewhat  uncertain.  Principally,  this  is 
because  the  median  row  of  spines,  a diagnostic  feature  of  Paracarinachites , is  only  rarely  expressed 
(Text-fig.  12c,/).  Given  the  quality  of  preservation,  including  the  survival  of  the  lateral  flanges,  it 
seems  implausible  that  the  median  spines  are  lost  because  of  poor  preservation.  Accordingly,  there 
seems  to  be  reason  to  retain  the  genus  Protopterygotheca  at  the  moment  as  separate  from 
Paracarinachites , and  refer  to  both  informally  as  paracarinachitids. 

Attention  should  be  drawn  also  to  problematical  fossils  from  Guizhou  that  Qian  and  Yin  (1984a; 
see  also  Wang  et  al.,  1984/;)  referred  to  as  Solenotia  (type  species  S.  lata , also  S.  lobata  and 
S.  elongata ; note  S.  incurva  (Wang  et  al.  1984a,  pi.  21,  fig.  17)  appears  to  be  a nomen  nudum).  The 
material  is  fragmentary  and  details  are  difficult  to  discern  in  the  published  photographs,  but  some 
specimens  may  be  comparable  to  P.  leshanensis  (see  in  particular  Qian  and  Yin  1984a,  pi.  5,  figs  1 
and  4). 


DISCUSSION 

Scleritome  reconstruction 

In  Cambroclavus  (Mambetov  in  Mambetov  and  Repina  1979;  Bengtson  et  al.  1990)  and 
Deltaclavus  gen.  nov.  fused  assemblages  suggest  that  the  cataphract  scleritome  in  these  taxa  was 


EXPLANATION  OF  PLATE  9 

Figs  1-14.  Protopterygotheca  leshanensis  Chen  in  Qian  et  al.  1979.  1 and  2,  IGAS-BC-88-30182;  1,  dorsal  view; 
2,  oblique  view.  3,  IGAS-BC-88-30183,  ventral  view;  4 and  5,  IGAS-BC-88-30184;  4,  oblique  view;  5,  dorsal 
view;  6,  15,  IGAS-BC-88-30185;  6,  dorsal  view:  15,  wall  ultrastructure  showing  diagenetic  phosphatization 
and  endolithic  borings;  7,  IGAS-BC-88-301 86,  dorsal  view.  8 and  9,  IGAS-BC-88-30187;  8,  dorsal  view;  9, 
oblique  view.  10,  IGAS-BC-88-30188,  dorsal  view.  11  and  12,  IGAS-BC-88-30189,  holotype;  11,  dorsal 
view;  12,  lateral  view.  13,  IGAS-BC-88-30190,  dorsal  view.  14,  IGAS-BC-88-30191,  dorsal  view.  All  isolated 
sclerites  from  Bed  37,  Maidiping  Member.  Hongchunping  Formation  at  Maidiping  section,  Emei,  Sichuan, 
China.  Magnifications:  x 30  (Figs  1-6,  8-12);  x 60  (Figs  7,  13,  14);  x 400  (Fig.  15). 


PLATE  9 


CONWAY  MORRIS  and  CHEN,  Protopterygotheca 


392 


PALAEONTOLOGY,  VOLUME  34 


; 

1000  lim 

text-fig.  13.  Hypothetical  reconstruction  of  a partial  portion  of  the  scleritome  of  Protopterygotheca 

leshanensis. 


closely  integrated  with  longitudinal  files  articulating  via  facets  and  transverse  files  interlocking  by 
virtue  of  congruent  shapes  (Text-fig.  1 1 b,  d).  A reconstruction  of  the  sclerites  providing  a coating 
to  a worm-like  animal  thus  seems  reasonable,  in  a manner  analagous  to  Recent  spicule-bearing 
animals  such  as  aplacophorans  and  certain  turbellarians  (Rieger  and  Sterrer  1975).  In  at  least  some 
species  of  Cambroclavus , such  as  a new  species  from  Australia  (Bengtson  et  al.  1990),  the 
morphological  variation  of  the  sclerites  is  very  wide,  and  includes  many  sclerites  that  depart 
conspicuously  from  a bilaterally  symmetrical  shape.  In  this  new  Australian  species  it  was  postulated 
that  variability  of  sclerites  occurred  within  single  scleritomes,  and  that  mutual  accommodation 
between  differently  shaped  sclerites  could  lead  to  changes  in  sclerite  appearance  across  the 
scleritome.  Similarly,  in  Deiradoclavus  it  is  supposed  that  the  variability  of  sclerite  shape  was  typical 
of  individuals,  and  relatively  rapid  changes  in  sclerite  shape  across  the  scleritome  could  be 
accommodated  by  a series  of  minor  adjustments. 

However,  the  recognition  of  articulated  series  of  sclerites  in  double  layers  in  Deltaclavus  (Text- 
fig.  9 d~h)  hints  at  previously  unexpected  complexities  of  anatomy  in  this  taxon,  although  the 
morphological  similarities  and  comparable  age  (Text-fig.  2)  of  Deltaclavus  and  Deiradoclavus 
suggest  that  their  scleritomes  did  not  differ  radically  from  one  another.  Given  the  orderly 
appearance  and  sense  of  articulation  it  seems  unlikely  that  these  fused  assemblages  are  taphonomic 


CONWAY  MORRIS  AND  CHEN:  CAMBRIAN  PROBLEMATICA 


393 


artefacts,  formed  for  instance  by  folding  together  of  a single  layer.  Granted  that  they  are  original 
features,  then  one  interpretation  would  be  to  regard  them  as  arm-like  extensions,  analagous  for 
example  to  the  feeding  arms  of  various  pelmatozoan  echinoderms.  Deiradoclavus  gen.  nov.  is  known 
only  from  isolated  sclerites.  However,  reconstruction  as  a tightly  integrated  scleritome  (Text-fig. 
1 1 c)  is  plausible  given  the  distribution  of  concave  facet-like  areas  on  the  dorsal  and  ventral  surfaces. 

In  contrast  to  all  the  above  genera,  the  circular  outline  of  sclerites  of  Zhijinites  suggests  that  they 
were  separate,  possibly  studding  the  body  surface  and  isolated  by  areas  of  non-mineralized  cuticle 
(Text-fig.  1 1 a).  What  may  represent  an  intermediate  case,  with  some  sclerites  articulated  and  others 
isolated,  occurs  in  Paracarinachites  spinas.  In  this  taxon  some  sclerites  occur  in  fused  longitudinal 
rows,  whose  life  association  was  cogently  argued  for  by  Qian  and  Bengtson  (1989).  Co-occurring 
isolated  sclerites  in  part  may  have  been  derived  by  disarticulation  of  less  welded  portions  of  the 
scleritome,  but  other  sclerites  lack  any  obvious  zones  of  articulation  and  abutment. 

It  is  questioned  whether  the  remaining  species  of  Paracarinachites  and  Protopterygotheca  (see 
above)  are  either  closely  related  to  P.  spinus  or  to  the  zhijinitids  (see  also  Qian  and  Bengtson  1989, 
p.  56).  One  reason  to  propose  this  is  the  distinctive  morphology  of  P.  leshanensis  whose  similarity 
to  the  type  species  P.  sinensis  is  clear,  but  whose  derivation  from  any  cambroclave  morph  seems 
forced.  In  P.  leshanensis , where  sclerite  form  is  arguably  more  complete,  it  is  hypothesized  that  they 
could  have  formed  an  imbricated  row  (Text-fig.  13).  In  contrast  Qian  and  Bengtson  (1989,  p.  56) 
suggested  that  ‘Several  Paracarinachites  sclerites  were  positioned  close  to  each  other  in  a cone-like 
structure,  so  that  the  apical  ends  met  in  the  centre’,  while  similar  remarks  were  also  addressed  to 
the  possibly  related  Scoponodus. 

Biomineralization  and  mode  of  secretion 

The  original  composition  of  the  sclerite  wall  of  cambroclaves  appears  to  have  been  calcareous,  with 
evidence  surviving  from  steinkerns  and  phosphatic  replacement  for  an  originally  fibrous 
ultrastructure.  In  life  the  hollow  within  the  sclerites  is  believed  to  have  been  occupied  by  soft  tissue, 
presumably  including  secretory  epithelia.  Such  an  arrangement  is  thought  more  likely  than  having 
the  sclerites  covered  with  secretory  tissue.  However,  if  the  calcareous  wall  was  laid  down  by  internal 
tissue,  it  seems  that  initial  formation  or  additions  to  the  scleritome  must  have  entailed  patches  of 
secretory  tissue  that  formed  a template  whose  precise  expression  was  governed  by  the  bounding 
nature  of  the  adjacent  sclerites.  In  this  manner  accommodation  between  sclerites  to  produce  a well- 
integrated  scleritome  would  not  need  to  be  under  precisely  specified  genetic  control,  and  would  be 
responsive  to  local  morphology  and  possibly  damage  repair. 

The  relationship  between  the  tissue  enclosed  in  the  sclerite  and  any  surrounding  tissue  is  rather 
problematic.  A crude  analogy  might  be  drawn  with  echinoderm  ossicles,  which  contain  stereom 
tissue  but  are  embedded  in  mesoderm.  Although  pores  are  observed  on  the  inner  walls  of  the  spinose 
portion  of  Zhijinites  sclerites  (PI.  3,  fig.  4)  it  is  not  clear  if  soft  tissue  extended  to  the  outer  margin, 
especially  as  the  spines  are  envisaged  as  projecting  free  of  the  body  wall. 

In  P.  spinus  heavy  diagenetic  phosphatization  appears  to  have  obliterated  all  traces  of  original 
mineralogy.  However,  granted  that  the  fused  series  described  by  Qian  and  Bengtson  (1989) 
represent  a primary  association,  then  it  is  necessary  to  postulate  secretory  tissue  that  lay  beneath 
the  sclerite  series.  In  the  remaining  paracarinachitids  the  clear  distribution  of  growth  lamellae 
(Kerber  1988;  Qian  and  Bengtson  1989;  see  also  PI.  9,  figs  4 and  10)  suggests  that  secretory  tissue 
formed  a mantle-like  layer  responsible  for  production  of  mineralized  increments. 

Palaeoecology 

Scleritome  reconstruction  of  a new  species  of  Cambroclavus  from  Australia  (Bengtson  el  al.  1990) 
was  taken  to  indicate  a primarily  defensive  role,  presumably  against  predators  and  physical 
abrasion.  The  elongate  spines  arising  from  the  anterior  region  of  each  sclerite  would  be  an 
important  contributory  factor,  but  it  was  also  noted  that  their  recurved  nature  could  have  assisted 
in  grasping  substrates.  However,  if  Cambroclavus  was  a burrowing  organism,  then  one  might 
predict  an  allometric  change  in  spine  size  to  compensate  for  increase  in  body  size  in  comparison  with 


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habitation  of  a substrate  of  fixed  grain  size  (see  Aller  1974  for  an  analagous  example  in  bivalve 
molluscs).  Tentative  evidence  from  the  Australian  material,  however,  did  not  support  such  an 
allometric  response. 

Systematic  position 

The  relationships  of  cambroclaves  to  other  major  groups  remain  problematic.  Mambetov’s  (in 
Manrbetov  and  Repina  1979)  comparison  of  the  cambroclaves  to  the  protoconodont  Protohertzina 
and  conodont-like  Rhombocorniculum  seems  to  be  without  foundation.  Various  Chinese  workers 
(e.g.  Qian  and  Yin  1984fi)  have  placed  the  cambroclaves  in  the  Acanthocephala,  an  endoparasitic 
group  of  worms  with  no  known  fossil  record  (Conway  Morris  and  Crompton  1982).  This 
supposition  is  based  on  the  similarities  between  cambroclave  sclerites,  especially  of  Zhijinites,  with 
the  proboscis  hooks  of  acanthocephalans  (see  also  Qian  and  Xiao  1984,  p.  79).  However,  differences 
in  composition,  mode  of  secretion,  and  recognition  in  cambroclaves  of  an  integrated  scleritome, 
that  at  least  in  Deltaclavus  includes  ‘arm-like’  structures,  all  suggest  that  cambroclaves  are  unlikely 
to  be  related  to  acanthocephalans.  However,  in  the  absence  of  complete  scleritomes  and  associated 
soft-part  preservation,  the  wider  affinities  of  this  group  remain  uncertain. 

No  further  light  can  be  thrown  either  on  the  wider  affinities  of  the  paracarinachitids,  other  than 
the  tentative  proposal  that  P.  spinus  be  regarded  as  belonging  to  the  cambroclaves,  while  the 
remaining  species  of  Paracarinachites , possibly  together  with  Scoponodus  and  even  Ernogia  (see 
above),  be  regarded  as  a distinct  group.  What  is  clear,  however,  is  that  comparisons  between 
paracarinachitids  and  polyplacophorans  (e.g.  Yu  1989)  are  without  foundation,  a point  already 
cogently  made  by  Qian  and  Bengtson  (1989,  pp.  48-49). 


Acknowledgements.  Samples  from  Shaanxi  and  Sichuan  provinces  were  collected  during  a Royal 
Society-Academia  Sinica  Exchange  Scheme  in  1986.  Field  trips  to  Hubei  and  Yunnan  provinces  in  1987  were 
possible  thanks  to  the  organizers  of  an  International  Symposium  on  the  Terminal  Precambrian  and  Cambrian 
Geology,  Yichang,  Hubei.  S.C.  M.  acknowledges  support  for  attendance  from  a Royal  Society-China 
Agreement  on  Science  and  Technology  (CAST)  Exchange  Scheme.  A Royal  Society-USSR  Academy  of 
Sciences  Exchange  Scheme  allowed  S.C.M.  to  examine  relevant  material  from  Kazakhstan,  and  I am  most 
grateful  to  Dr  V.  V.  Missarzhevsky  for  his  generosity  in  allowing  access  to  collections.  Laboratory  work  was 
supported  by  the  Nuffield  Foundation  (One  Year  Science  Research  Fellowship)  and  NERC  (research  grant 
GR3/6456),  to  whom  grateful  acknowledgement  is  made.  Fossil  picking  by  Zoe  Conway  Morris,  technical 
assistance  by  Liz  Harper,  Ken  Harvey,  David  Newling,  Sarah  Skinner  and  Sarah  Palmer,  and  extensive  typing 
by  Sandra  Last  are  all  warmly  appreciated.  Valuable  reviews  by  Stefan  Bengtson  and  Adrian  Rushton  are  also 
appreciated.  Cambridge  Earth  Sciences  Publication  1645. 


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qin  hongbin  and  yuan  xiaoqi.  1984.  Lower  Cambrian  Archaeocyatha  from  southern  Shaanxi  province, 
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ROZANOV,  A.  YU.,  MISSARZHEVSKY,  V.  V.,  VOLKOVA,  N.  A.,  VORONOVA,  L.  C.,  KRYLOV,  I.  N.,  KELLER,  B.  M., 

korolyuk,  i.  k.,  lendzion,  k.,  michniak,  R.,  pykhova,  n.  g.  and  sidorov,  a.  d.  1969.  The  Tommotian  stage 


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wang  yangeng,  yin  gongzheng,  zheng  shufang,  qian  yi  et  cil.  1984a.  The  Smian-Cambrian  boundary  in 
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— 1984b.  Biostratigraphy  of  the  boundary  Sinian-Cambrian  in  the  Yangzi  area  of  Guizhou. 
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xie  yongshun.  1988.  Small  shelly  fossils  in  Qiongzhusi  Stage  of  Lower  Cambrian  in  Zhenba  County,  Shaanxi 
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in  the  Yangtze  Gorges  area.  Geological  Publishing  House,  Beijing,  182  pp.  [In  Chinese  and  English], 

S.  CONWAY  MORRIS 

Department  of  Earth  Sciences 
Downing  Street 
Cambridge  CB2  3EQ,  UK 

CHEN  MENGE 

Institute  of  Geology 
Academia  Sinica 
Beijing 

People’s  Republic  of  China 


Typescript  received  19  December  1989 
Revised  typescript  received  11  May  1990 


THE  OSTRACODERM  PHIALASPIS  FROM  THE 
LOWER  DEVONIAN  OF  THE  WELSH  BORDERLAND 

AND  SOUTH  WALES 

by  P.  R.  TARRANT 


Abstract.  The  Lower  Devonian  ostracoderm  Phialaspis  symondsi  differs  sufficiently  from  the  type  species  of 
the  Traquairaspididae,  Traquairaspis  campbelli , to  place  it  within  a separate  family,  the  Phialaspididae.  This 
family  also  includes  Toombsaspis  pococki  comb,  nov.,  T.  sabrinae  comb.  nov.  and  Munchoaspis  denisoni  comb, 
nov.  The  Traquairaspididae  includes  Traquairaspis  campbelli  and  Rimasventeraspis  angusta  comb.  nov.  A new 
reconstruction  of  the  carapace  of  Phialaspis  symondsi  is  given  and,  from  an  examination  of  immature  plates, 
a possible  mode  of  growth  is  outlined.  Likely  feeding  and  respiratory  mechanisms  are  discussed.  A new  form 
of  jet-aided  steering  is  proposed  for  phialaspidid  ostracoderms. 

The  inner  surface  of  a heterostracan  ventral  median  plate  was  described  by  Lankester  (1868)  as 
Cyathaspis  symondsi.  Later  Traquair  (1898)  described  plates  with  a stellate  tubercular  ornament  as 
Psammosteus  anglicus , from  which  the  Psammosteus  Limestone  is  named.  Wills  (1935)  and  White 
(1946)  described  the  morphology  of  the  carapace  under  the  name  Phio/aspis  combining  Lankester’s 
and  Traquair’s  material  (transferred  to  Traquairaspis  in  1948  by  White  and  Toombs).  More 
recently,  Dineley  and  Loeffler  (1976)  have  added  to  the  knowledge  of  general  traquairaspidid 
morphology  by  their  descriptions  of  Canadian  material  with  dorsal  shields  formed  of  fused  plates. 

The  bulk  of  the  Phialaspis  symondsi  material  described  in  this  work  (over  200  specimens)  came 
from  Devil’s  Hole  stream  section  (also  known  as  the  Lye  Brook:  White  and  Toombs  1948;  White 
19506;  Ball  and  Dineley  1961)  which  dissects  the  Lower  Devonian,  Downton/Ditton  Group 
transition  (White  1950c/)  of  the  Lower  Old  Red  Sandstone,  Morville  district,  Shropshire.  This  is 
mainly  the  result  of  sixteen  years  of  collecting  by  Mr  A.  M.  Tarrant  and  the  author.  Also  included, 
are  descriptions  of  specimens  collected  from  the  site  by  the  late  Mr  H.  A.  Toombs  and  Professor 
D.  L.  Dineley,  and  material  collected  to  be  studied  as  part  of  a palaeoecological  project  when  the 
Nature  Conservancy  excavated  the  site  in  1981.  Material  of  Phialaspis  symondsi  and  Toombsaspis 
pococki  collected  from  elsewhere  within  the  Anglo-Welsh  Region  (Text-fig.  I)  and  the  Scottish 
Traquairaspis  campbelli  was  also  studied. 


ANGLO-WELSH  LOCALITIES 

Details  of  localities  2-4  and  6-14  are  listed  in  Ball  and  Dineley  (1961).  Further  information  on  all 
the  localities  given  below  is  deposited  with  the  Nature  Conservancy  Council,  Geological  Review 
Unit,  Peterborough,  to  which  enquiries  may  be  directed. 

Shropshire  ( Clee  Hills  District)'.  (1)  Barnsland  Farm  Quarry;  (2)  Clapgate  Quarry ; (3)  Devil’s  Hole; 
(4)  Earnstrey  Brook;  (5)  Gardener’s  Bank;  (6)  Great  Oxenbold  Stream;  (7)  Hudwick  Dingle; 
(8)  Kidnall  Gutter;  (9)  Little  Oxenbold;  (10)  New  Buildings;  (II)  New  Inn;  (12)  Oak  Dingle; 
(13)  Sudford  Dingle;  (14)  Targrove  Quarry.  Phialaspis  symondsi  is  found  at  all  these  localities,  with 
Toombsaspis  pococki  found  in  addition  in  a separate  horizon  at  locality  5. 

Hereford  and  Worcester : (15)  Birch  Hill  Quarry,  The  Trimpley  Inlier;  (16)  Cradley  Quarries,  The 
Trimpley  Inlier;  (17)  Common  Bach,  Dorstone,  Black  Mountain  District;  (18)  Cusop  Dingle,  Black 


| Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  399^438,  6 pls.| 


© The  Palaeontological  Association 


400 


PALAEONTOLOGY,  VOLUME  34 


' Hay  on  Wye 

YLBLACkufcVC 

MOUNTAINS 

’Brecon. 


Hereford 


ifTenby 
ox  CALDY 
ISLE 


CARDIFF 


KEY 


LowerOld  Red  Sandstone 

0 

Phialaspis  symondsi 

X 

Toombsaspis  pococki 

s 

Toombsaspis  sabrinae 

D Y F E D 

Carmarthen 


BRISTOL  CHANNEL 


SHROPSHIRE 

CLUN  FOREST 


) 

Much  Wenlock 


POWYS 


. -cP  GLEE. 

• o0  HILLS 
Ludlow- 

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TRIMPLEY 

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HEREFORD  & WORCESTER 


' ■•'..  •Ross  on  Wye 

o • ■ 

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GWENT 


Newport 


0 10  20  30  40  50 

scale  in  km 


text-fig.  1.  Known  phialaspidid  localities  in  the  Anglo-Welsh  Lower  Old  Red  Sandstone,  indicated  by 

symbols  as  shown  in  the  key. 


Mountain  District;  (19)  Eastham  Brook,  The  Trimpley  Inlier;  (20)  Heath  Farm,  Wolferlow,  The 
Trimpley  Inlier;  (21)  Holheach  House  Stream,  The  Trimpley  Inlier;  (22)  House  of  the  Wood 
Quarry,  Garnon’s  Hill,  Heightington ; (23)  Hurtlehill  Farm  Quarry,  Heightington ; (24)  Llan  Farm, 
Dorstone,  Black  Mountain  District;  (25)  Man  Brook,  The  Trimpley  Inlier;  (26)  Mary  Moors,  The 
Trimpley  Inlier;  (27)  Merbach  Brook,  Ledbury;  (28)  Park  Atwood  Stream,  The  Trimpley  Inlier; 
(29)  Ross  Motorway,  M50  section;  (30)  Sapey  Brook,  Thrift  Farm;  (31)  Shatterford,  Boundry 
Brook,  The  Trimpley  Inlier;  (32)  Westhope  Hill,  near  Hereford;  (33)  Witchery  Hole,  Clifton  on 
Teme.  Phialaspis  symondsi  found  at  all  localities  except  28  and  31,  at  which  Toombsaspis  pococki 
was  found.  Both  species  present  at  localities  18  and  33,  in  the  same  horizon  only  at  the  latter. 

Powys'.  (34)  Onen,  Court  Wood  Quarries;  (35)  Pen-y-lan,  Crwcws  Wood  Quarries.  Phialaspis 
symondsi  found  at  both  localities. 

Gwent  '.  (36)  Alteryn  Quarry,  Toombsaspis  pococki ; (37)  Coed-y-coedcae,  Phialaspis  symondsi ; (38) 
Penrhos  Farm  Quarry,  Phialaspis  symondsi. 

Gloucestershire'.  (39)  Lydney,  Phialaspis  symondsi ; (40)  Sharpness  Docks,  Toombsaspis  sabrinae. 

Dyfed:  (41)  Caldy  Island,  Phialaspis  symondsi , Toombsaspis  pococki  (several  horizons);  (42) 
Freshwater  West,  Phialaspis  symondsi;  (43)  Manorbier  Bay,  Phialaspis  symondsi. 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


401 


MATERIALS  AND  METHODS 

To  obtain  information  about  their  outer  surfaces,  the  Toombs  and  Rixon  (1950)  transfer  method 
was  used  on  several  specimens.  This  entailed  mounting  the  specimens  on  clear  resin,  and  removing 
the  matrix  with  acetic  acid.  Although  several  specimens  prepared  reasonably  well,  the  results  were 
mixed.  The  larger  plates  had  a tendency  to  be  destroyed  by  the  acid  owing  to  the  calcite  infill  of  their 
cancellous  spaces.  A limited  amount  of  success  in  tracing  the  sensory  canal  system  came  from 
impregnating  certain  specimens  with  oil  of  aniseed  and  viewing  them  in  transmitted  light.  Often  it 
was  necessary  to  remove  the  aspidin  with  dilute  hydrochloric  acid  (White  1935,  1946).  Many 
specimens  were  not  prepared  because  of  the  risk  of  damage  to  their  inner  surfaces. 

The  bulk  of  material  is  new  and  is  housed  in  Ludlow  Museum,  Shropshire,  SHRCM.G  -235 
specimens,  and  in  the  National  Museum  of  Wales,  Cardiff,  NMW  - 6 specimens.  Other  specimens 
studied  are  from  established  collections  housed  in  the  following  museums:  British  Geological 
Survey  Museum,  Kegworth,  Notts.,  BGS  (GSM);  British  Museum  (Natural  History),  London, 
BMNH;  University  of  Birmingham  Geology  Museum,  BU;  National  Museum  of  Canada,  Ottawa, 
NMC;  Princeton  University  Geological  Museum,  New  Jersey,  USA,  PU;  Royal  Museum  of 
Scotland,  Edinburgh,  RSM ; W.  F.  Whittard  collection,  S. 

STRATIGRAPHY  AND  PALAEOECOLOGY 

Most  of  the  heterostracans  described  in  this  work  came  from  the  Upper  Downton  Group,  Lower 
Old  Red  Sandstone,  Anglo-Welsh  Region.  The  stratigraphy  and  sedimentology  of  this  area  have 
been  documented  by  Ball  and  Dineley  (1961);  Allen  and  Tarlo  (1963);  Allen  (1964,  1974r/,  19746, 
1985);  and  Allen  and  Williams  (1978,  1981).  It  is  dominated  by  red  mudstones,  which  are 
interspersed  with  discrete  beds  of  upwardly  fining,  current-influenced  units  of  sandstones  and 
intraformational  conglomerates.  The  conglomerates  usually  hold  the  largest  concentrations  of 
vertebrate  fossils. 

Most  recent  workers  in  the  field  have  considered  that  they  represent  infilled  freshwater  channel 
complexes,  within  an  extensive  deltaic  floodplain  (Ball  and  Dineley  1961;  Allen  and  Tarlo  1963; 
Allen  1964,  1974 a,  19746). 

The  area  is  dissected  by  the  Psammosteus  Limestone,  a pedogenic  feature  (see  Allen  1974u,  1985), 
which  divides  the  Downton  from  the  overlying  Ditton.  Although  rare  specimens  of  Phialaspis 
symondsi  have  been  found  above  the  Psammosteus  Limestone,  this  horizon  marks  a distinctive 
faunal  change,  where  the  phialaspids  are  replaced  by  pteraspidiforms  (White  1950r/;  Ball  and 
Dineley  1961). 

White  (1950(3)  used  Phialaspis  symondsi  as  a zone  fossil  marking  the  uppermost  Downton,  and 
Toombsaspis  pococki  to  mark  the  underlying  zone.  The  base  of  the  range  of  Phialaspis  symondsi  is 
about  30  m below  the  Psammosteus  Limestone.  Recent  field  studies  (Rowlands  and  Tarrant, 
unpublished  data),  would  suggest  that  the  top  of  its  range  is  considerably  less  than  Ball  and 
Dineley’s  (1961)  claim  of  c.  53  m above  the  Psammosteus  Limestone.  The  bulk  of  Toombsaspis 
pococki  material  studied  by  White  (1946),  came  from  5 m below  the  Psammosteus  Limestone  at 
Gardener’s  Bank,  Shropshire,  which  is  the  top  of  its  range.  Squirrel  and  Downing  ( 1969)  collected 
fragments  which  they  considered  to  belong  to  this  species  from  158  m below  the  Psammosteus 
Limestone  at  Ateryn  Quarry,  Gwent,  which  may  be  the  bottom  of  its  range.  However,  it  would 
appear  that  the  two  species  substantially  overlapped  in  time. 

They  have  only  been  recorded  together  at  the  Witchery  Hole,  Clifton  on  Teme,  Hereford  and 
Worcester  (Ball  and  Dineley  1961),  where  the  material  was  in  loose  blocks  and  may  have  originated 
from  different  horizons  (M.  A.  Rowlands,  pers.  comm.).  As  Ball  and  Dineley  suggested,  this  could 
indicate  that  they  occupied  different  environments.  Following  this,  the  two  species  are  mainly  found 
with  different  vertebrate  faunas.  Phialaspis  symondsi  is  characteristically  found  with  Tesseraspis 
tesselata , Anglaspis  macculloughi , Corvaspis  kingi,  Turinia  pagei , cephalaspids,  Ischnacanthus 
wickhami  and  other  acanthodians  (Ball  and  Dineley  1961;  Turner  1973).  It  is  also  occasionally 


402 


PALAEONTOLOGY,  VOLUME  34 


found  with  Protopteraspis  gosseleti , Pteraspis  rostrata  and  Nodonchus  sp.  Toombsaspis  pococki  is 
associated  with  Tesseraspsis  tesselata,  Didymaspis  grindrodi  and  other  cephalaspids,  the  Goniporus- 
Katoporus  thelodont  fauna,  Ischnacanthus  kingi  and  other  acanthodians  (White  1946;  Turner 
1973). 

It  would  seem  that  the  overlapping  vertebrate  assemblages  of  the  horizons  subjacent  to  the 
Psammosteus  Limestone  are  related  as  much  to  varying  ecological  conditions  as  they  are  to  time. 
Indeed,  Karatajute-Timalaa  (1978)  and  Blieck  (1984)  proposed  that  the  zones  of  Traquairaspis 
symondsi  and  Traquairaspis  pococki  should  be  amalgamated  into  a single  Traquairaspis  zone. 
However,  because  of  the  reclassification  of  these  species  in  this  work,  it  is  proposed  that  it  should 
be  renamed  the  Phialaspis  symondsi-Toombsaspis  pococki  zone. 

As  Ball  and  Dineley  (1961)  observed,  the  vertebrate  remains  are  often  fragmented,  and 
concentrated  in  pockets  with  individual  specimens  of  a similar  size,  buoyancy,  or  weight,  suggesting 
that  they  were  probably  originally  transported,  water  selected,  and  in  some  cases  may  have  been 
reworked.  Their  preservation  is  usually  good,  often  showing  fine  details,  and  the  vascular  cancellous 
layers  are  normally  not  crushed,  because  of  calcite  infilling. 


SYSTEMATIC  PALAEONTOLOGY 

Subclass  heterostraci  Lankester,  1868 
Order  traquairaspidiforme  Tarlo,  1962 

Diagnosis.  (After  Dineley  and  Loeffler  1976).  Dorsal  shield  comprises  either  single  plate  or  single 
dorsal  disc,  rostral  and  pineal  plates,  and  paired  orbital,  branchio-cornual  or  branchial  and  cornual 
plates.  Orbital,  pineal  and  branchial  openings  enclosed.  Ornamentation  of  dorsal  shield  often  of 
elevated,  laterally  serrated  tubercles,  commonly  with  narrow  interstitial  tubercles  or  ridges,  mainly 
arranged  in  cyclomoriform  units,  sometimes  with  outer  adult  plate  growth.  Ventral  disc  ovate  to 
elongate,  with  lateral  ornamentation  similar  to  dorsal  shield,  becomes  broader  and  flatter  towards 
longitudinal  midline,  or  replaced  by  smooth,  flat,  ovate  central  area.  Lateral  line  system  variable, 
ranging  from  pattern  of  longitudinal  canals  and  transverse  commissures  to  anastomosing  network. 

Discussion.  Although  Weigeltaspis  may  prove  to  be  a traquairaspidiform  (Obruchev  1964;  Blieck 
1983),  this  has  yet  to  be  established.  It  is  possible  that  the  Canadian  ? Traquairaspis  and  Nat/aspis 
Dineley  and  Loeffler,  1976,  with  ornamented  ventral  central  regions,  may  prove  to  represent 
different  evolutionary  lineages  from  those  species  with  smooth  ventral  central  regions. 

White  (1950a)  realised  that  the  specimens  he  had  described  as  Phialaspis  pococki  subsp.  cowiensis 
White,  1946  were  ventral  discs  of  Traquairaspis  campbelli , and  he  reclassified  Phialaspis  pococki  and 
Phialaspis  symondsi  as  members  of  the  genus  Traquairaspis.  However,  following  Halstead’s  (1982) 
retention  of  the  name  Phialaspis , the  British  species  can  be  divided  into  two  distinct  morphological 
groups.  They  are  considered  in  this  work  to  represent  two  distinct  families,  the  Traquairaspididae 
and  the  Phialaspididae. 


Family  phialaspididae  White,  1946 


Type  genus.  Phialaspis  Wills,  1935 

Other  genera  assigned.  Toombsaspis  gen.  nov.,  Munchoaspis  gen.  nov. 

Diagnosis.  Dorsal  shield  usually  comprises  seven  separate  plates.  Dorsal  disc  quadrate,  vaulted 
posteriorly,  with  median  row  of  large  cyclomoriform  units  on  posterior  half  forming  a keel,  and 
usually  a dorsal  vane.  Ventral  disc  flattening  and  widening  anteriorly  with  raised,  smooth,  coffin- 
shaped central  area,  situated  more  posteriorly  than  anteriorly  and  enclosed  by  ornamented  margin 
of  disc.  Two  rows  of  longitudinally  running,  large  cyclomoriform  units  on  each  lateral  side  of  dorsal 
disc,  one  row  on  each  lateral  side  of  ventral  disc,  another  row  on  dorsal  side  of  each  branchio- 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


403 


cornual  plate.  Regions  of  cyclomoriform  adult  growth  on  anterior  and  lateral  edges  of  dorsal  and 
ventral  discs.  Paired  lateral  plates,  with,  quite  frequently,  separate  paired  post  oral  plates. 

Genus  phialaspis  Wills,  1935 
Type  species.  Cyathaspis  ( ? ) symondsi  Lankester,  1 868 

Diagnosis.  Large  advanced  Phialaspididae.  Dorsal  discs  more  vaulted  than  ventral  disc.  Dorsal 
vane  large  with  two  cyclomoriform  units,  median  keel  with  one.  Rostrum  enlarged.  Branchio- 
cornual  plates  with  lateral  keels  terminating  posteriorly  in  lateral  vanes.  Ventral  disc  with  non- 
unital  cyclomoriform  growth  between  longitudinal  units  and  smooth  central  region,  with  three  units 
positioned  behind  and  sometimes  fused  to  its  posterior  edge.  Ornament  of  stellated  tubercles,  which 
are  often  ringed  on  the  reticular  layer  by  a groove  or  shelf. 


Phialaspis  symondsi  (Lankester,  1868) 

Plates  1-4;  Plate  5,  figs  2-5;  Plate  6;  Text-figs  1 10,  13,  14a,b,  15a-g.  16;  Table  I 

1868  Cyathaspis  (?)  symondsi  Lankester,  p.  27,  pi.  6,  fig.  5. 

1898  Psammosteus  anglicus  Traquair,  p.  67,  pi.  1,  figs  1 and  2. 

1935  Phialaspis  symondsi  (Lankester);  Wills,  pp.  439^444,  pis  5-7;  text-fig.  4. 

1948  Traquairaspis  symondsi  (Lankester);  White  and  Toombs,  p.  7. 

Holotype.  BGS(GSM)31 380,  ventral  disc. 

Horizon  and  localities.  Upper  Silurian/Lower  Devonian.  Uppermost  Downton  and  Lowest  Ditton  Groups, 
Anglo-Welsh  region  (see  Text-fig.  1). 

Referred  material.  SRCH.G:  213  from  Devil’s  Hole,  13  from  Little  Oxenbold,  6 from  Earnstry  Brook,  2 from 
Barnsland  Farm  Quarry,  1 from  Oak  Dingle;  NMW : 2 from  Cusop  Dingle,  1 from  Lydney  and  3 from 
Manorbier  Bay;  material  in  the  BMNH,  BGS(GSM),  and  BU.  This  material  consists  of  27  dorsal  discs,  14 


table  1 . Maximum  dimensions  of  adult  Phialaspis  symondsi  plates  in  millimetres.  Abbreviation : pop,  post- 
oral process. 


Range 

Average 

Length 

Width 

Ratio  of  width 
to  length 

Length 

Width 

Ratio  of 
width 
to  length 

Dorsal  discs 

50-70 

40-60 

0-67-0-96 

60 

49 

0-80 

Orbital  plates 

26-34 

12-22 

0-44-0-56 

30 

16 

0-52 

Pineal  plates 

9-20 

10-20 

0-85-1-33 

14 

15 

1-07 

Rostrums 

13-17 

21-24 

1-23-1-84 

15 

22 

1 46 

Branchio-cornuals 

60-80 

35-37 

0-43-0-55 

68 

35 

0-51 

Ventral  discs 

68-100 

42-64 

0-54-0-75 

81 

50 

0-61 

Lateral  plates  + pop 

26-43 

14-24 

0-48-0-61 

36 

20 

0-56 

Lateral  plates  — pop 

20-31 

16-23 

0.67-0.90 

25 

19 

0-76 

Curvital  dimensions 

Dorsal  discs 

51-77 

50-74 

0-76-1  08 

64 

60 

0-93 

Branchio-cornuals 

94-116 

100 

Ventral  discs 

69-101 

44-74 

0 61 

83 

59 

0-71 

0.78 


404 


PALAEONTOLOGY.  VOLUME  34 


dorsal  vanes,  20  orbital  plates,  10  pineal  plates,  7 rostral  plates,  26  branchio-cornual  plates,  74  ventral  discs, 
20  lateral  plates,  5 oral  plates,  plus  scales  and  fragments. 

Diagnosis.  As  for  genus. 

Description.  The  dorsal  disc  (PI.  1,  figs  1 and  2;  PI.  2,  fig.  2;  Text-fig.  2)  is  highest  and  widest  about  halfway 
along  its  length.  Its  lateral  margins  are  gently  scalloped,  and  the  anterior  margin  is  sometimes  angled  and 
slightly  indented  to  match  the  contact  with  the  posterior  margin  of  the  pineal  plate  and  the  dorso-posterior 
margins  of  the  orbital  plates.  The  two  lateral  rows  of  units  are  most  pronounced  at  the  posterior  of  the  first, 
most  medially-placed  row,  and  along  the  second  row,  internal  impressions  marking  their  edges  can  often  be 
seen  (PI.  1,  fig.  2;  Text-fig.  2b).  The  cancellae  are  enlarged  under  the  apex  of  each  unit  causing  the  exoskeleton 


text-fig.  2.  Phialaspis  symondsi  (Lankester),  dorsal  discs,  a,  part  superimposed  on  counterpart  to  show 
ornamentation  and  incomplete  sensory  canals,  SHRCM.G08137/1-2.  B,  incomplete  and  mainly  internal 
mould  in  plan  and  lateral  views,  a-a,  b-b,  lines  of  cross  section,  SHRCM.G08138.  c,  part  superimposed  on 
counterpart  to  show  sensory  canal  system,  SHRCM.G08139/1-2.  d,  incomplete  juvenile  showing  developing 
ornament,  c-c,  line  of  cross  section,  SHRCM.G08140.  e,  incomplete  specimen  with  part  superimposed  on  to 
counterpart  to  show  sensory  canal  system,  SHRCM.G08141/1-2.  Abbreviations:  ag,  adult  growth  region;  dv, 
dorsal  vane;  imu,  internal  impressions  of  units;  ltc,  lateral  transverse  commissure;  mdc,  medial  dorsal 
longitudinal  canal;  mtc,  medial  transverse  commissure;  sp,  sensory  pore. 


to  swell  from  1 to  2 mm  in  thickness.  With  the  exception  of  the  large  tubercle  or  frequently  large  tubercles, 
capping  the  apex,  the  tubercles  are  small  and  irregular  on  the  units.  This  contrasts  with  the  larger  and  more 
equilateral  tubercles  found  on  the  peripheral  adult  zone  (Text-fig.  2 a),  where  a longitudinal  fold  can  sometimes 
be  observed  on  each  lateral  side  of  the  larger  dorsal  discs.  This  is  so  vestigial  that  it  could  hardly  be  described 
as  a row  of  units. 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


405 


text-fig.  3.  Phialaspis  symondsi  (Lankester),  dorsal  vanes,  a,  lateral  view  SHRCM.G08142.  b,  cross  section 
at  a-a.  c,  short  high  specimen,  SHRCM.G08143.  d,  adolescent  specimen,  SHRCM.G08144.  e,  long  low 
specimen,  showing  ornamental  details,  SHRCM.G08145.  f,  ditto,  posterior  view.  Abbreviations;  ae,  anterior 
element;  dr,  developing  region;  pe,  posterior  element. 

The  dorsal  vane  (PI.  1,  figs  3-5;  Text-fig.  3)  is  triangulate  and  varies  in  proportion,  ranging  from  34  mm 
long  x 21  mm  high  to  19  mm  long  x 26  mm  high  and  is  7-10  mm  thick  at  its  base.  Its  two  specialized  units  are 
often  in  tandem,  with  a doubled  and  thickened  cancellous  layer  which  narrows  towards  the  tip  and  divides  at 
the  base  to  merge  with  the  disc.  The  rear  unit  is  normally  largest.  However,  the  dorsal  vane  of 
SHRCM.G08137  (PI.  1,  fig.  6)  has  an  atrophied  rear  unit,  and  is  mainly  formed  from  the  front  unit. 

Although  broken  at  its  anterior  end,  the  dorsal  vane  SHRCM.G08140  (PI.  1,  fig.  3;  Text-fig.  3d)  is  small, 
only  17  mm,  in  height.  A depressed  region  running  longitudinally  just  above  its  base  may  indicate  an  area  of 
growth. 

An  incomplete  and  immature  dorsal  disc  SHRCM.G08140  measures  17  mm  long  x 24  mm  double  half  width 
(PI.  2,  fig.  2;  Text-fig.  2d).  Its  dorsal  vane  is  shown  in  section  and  is  5 mm  high  x 3 mm  thick  at  the  base.  The 
medial  longitudinal  sensory  canals  have  been  exposed  and  are  much  closer  together  than  on  the  larger  dorsal 
discs.  All  levels  of  its  exoskeleton  were  present.  The  surface  is  pitted  with  openings  on  the  more  complete  left 
lateral  and  anterior  edges.  This  grades  inwards  via  developing  tubercles  (Text-fig.  2d)  to  well-formed  large 
tubercles  not  arranged  in  cyclomoriform  patterns. 

The  orbital  plates  (PI.  2,  fig.  1 ; Text-fig.  4a-c)  are  elongate  and  irregularly  diamond-shaped,  with  usually 
concave  dorsal  edges  to  accommodate  the  pineal  plate.  They  are  curved  to  present  dorsal  and  lateral  sides 
towards  the  front,  and  become  flattened  towards  the  back  to  slope  at  a dorso-lateral  angle.  The  orbital  opening 
ranges  from  2 to  3 mm  in  diameter;  it  is  on  the  angle  of  the  dorso-lateral  fold,  and  is  usually  slightly  nearer 
the  anterior  edge  of  the  plate  than  the  posterior. 

The  pineal  plate  (PI.  2,  fig.  3;  Text-fig.  4d-g)  is  distinguished  by  its  flat  and  more  or  less  rhomboid  shape. 
There  is  a centrally  placed  pineal  foramen,  which  is  approximately  1 mm  in  diameter.  The  tubercles  on  the 
pineal  and  orbital  plates  are  arranged  in  concentric  rings  around  the  pineal  and  orbital  openings. 

The  dorsal  side  of  the  rostrum  (PI.  2,  fig.  6;  Text-fig.  5 c)  is  rounded  and  highest  at  the  posterior  edge  which 
is  three-pointed,  with  two  concave  edges  which  would  have  accommodated  the  front  of  the  orbital  plate.  The 
plate  tapers  towards  a tip  formed  by  large  horizontally  running  tubercles. 

The  ventral  pre-oral  surface  (PI.  2,  fig.  4;  Text-fig.  5a)  has  a raised,  flat  central  region,  which  probably 
represents  an  area  of  a similar  kind  to  the  pre-oral  field  found  on  certain  pteraspidiforms.  With  the  exception 
of  several  long  tubercles  traversing  the  anterior  half,  it  is  ornamented  with  small  and  atrophied  tubercles. 
Posterior  to  the  pre-oral  surface  and  rimmed  with  a maxillary  flange  on  the  angle  of  ascent,  the  pre-oral  wall 
ascends  vertically  to  join  the  posterior  undersurface  of  the  plate.  The  basal  laminated  layer  on  the  posterior 
undersurface  of  SHRCM.G08161  (Text-fig.  5a)  is  folded  and  contorted  on  each  side  of  a shallow  median 
groove. 

The  larger  specimens  have  proportionally  longer  pre-oral  regions.  On  the  smallest  rostrum,  NMW88.32G. 
(PI.  2,  fig.  5;  Text-fig.  5d),  the  pre-oral  region  is  0-28  times  the  length  and  0-60  times  the  width  of  the  pre-oral 
region  of  SHRCM.G08161 . It  is  broken  along  its  posterior  edge,  and  has  all  exoskeletal  layers  present.  Its  small 
size  and  proportions  indicate  it  was  from  an  immature  animal.  A strong  depression  on  each  side  of  the  pre- 
oral surface  shows  regions  of  possible  active  growth.  The  basal  laminated  layer  of  the  posterior  undersurface, 
along  its  junction  with  the  pre-oral  wall,  is  perforated  with  vascular  foramina  often  set  within  large  depressions 
(Text-fig.  5d)  which  appear  to  match  the  contorted  conditions  found  in  this  region  on  SHRCM.G08161. 


406 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  4.  Phialaspis  symondsi  (Lankester).  a-c,  orbital  plates;  a,  right  plate,  part  superimposed  on 
counterpart  to  show  sensory  canal  system,  a-a,  b-b,  c-c,  d-d,  lines  of  cross  section, 
SHRCM.G08147/1-2;  b,  right  plate  showing  sensory  canal  system,  NMW88.32G.2;  c,  right  plate,  part 
superimposed  on  counterpart  to  show  ornamentation  and  sensory  canal  system,  SHRCM.G08146/1-2.  d-g, 
pineal  plates;  d,  small  plate,  part  superimposed  on  counterpart  to  show  part  of  sensory  canal  system,  a-a,  b-b, 
lines  of  cross  section,  SHRCM.G08148/1-2 ; e,  small  plate,  part  superimposed  on  counterpart  to  show  sensory 
canal  system,  SHRCM.G08149/1-2 ; f,  fragmentary  large  plate,  part  superimposed  on  counterpart  to  show 
part  of  sensory  canal  system,  SHRCM.G0815/1-2;  G,  fragmentary  large  plate  showing  pineal  opening  and 
ornamental  details,  SHRCM.G08 1 51 . Abbreviations:  cor,  circum-orbilal  canal;  ior,  inter-orbital  canal;  ldc, 
dorsal  longitudinal  canal;  ltc.  lateral  transverse  commissure;  mdc,  medial  dorsal  longitudinal  canal;  or,  orbit; 
pi,  pineal  organ;  sor,  supra-orbital  canal;  sp,  sensory  pores. 


The  branchial  opening,  located  about  three-fifths  of  the  way  along  the  length  of  the  branchio-cornual  plate 
(PI.  3,  figs  4 and  5;  Text-fig.  6)  is  dorsally  facing  and  ovate,  and  ranges  in  size  from  8x4  mm  to  11x7  mm. 

The  lateral  keel  embraces  the  lateral  side  of  the  branchial  duct  and  encloses  the  front  of  the  branchial 
opening.  Its  vascular  cancellous  layer  is  greatly  thickened  and  individually  variable,  ranging  from  5-12  mm 
wide  x 4-10  mm  thick  regardless  of  the  size  of  the  rest  of  the  plate.  Elongated  and  longitudinally  running  rows 
of  tubercles  are  found  on  both  sides  of  this  region.  On  its  lateral  edge,  closely  spaced,  1 mm  thick  tubercles 
overlie  smaller  primary  tubercles  (Text-fig.  6 b).  Occasionally,  there  are  regions  of  abrasion  on  the  ventral  side 
(Text-fig.  6d). 

The  lateral  vane  occupies  from  the  back,  one  half  to  one  third  the  length  of  the  branchio-cornual  plate  and 
joins  the  lateral  keel.  It  is  solid,  triangulate,  and  dorso-ventrally  flattened,  with  two  greatly  thickened  vascular 
cancellous  layers.  Measuring  7 mm  thick  at  its  base  on  SHRCM.G08194,  it  forms  the  postero-lateral  edge  of 
the  branchial  opening.  The  whole  vane  is  tilted  postero-laterally,  with  an  elongated  region  of  small  and 


EXPLANATION  OF  PLATE  1 

Figs  1-6.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland.  1,  2,  6,  dorsal  discs,  x2;  1, 
SHRCM.G08166/1,  dorsal  view  of  external  mould;  2,  SHRCM.G08243/1,  dorsal  view  of  small  internal 
mould  showing  impressions;  6,  SHRCM.G08166,  lateral  view  of  silicon  rubber  impression  showing 
malformed  dorsal  vane.  3-5,  dorsal  vanes,  x2;  3,  SHRCM.G08140,  external  cast  of  immature  vane;  4, 
SHRCM.G08143,  external  cast;  5,  SE1RCM.G08145,  external  cast. 


PLATE  1 


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Sim 


TARRANT,  Phialaspis  symondsi 


408 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  5.  Phialaspis  symondsi  (Lankester),  rostral  plates,  a,  ventral  view  showing  details  of  tip  and  posterior 
undersurface,  a-a,  line  of  cross  section,  SHRCM.G08160.  b,  fragmentary  specimen,  showing  pre-oral  wall  and 
part  of  pre-oral  surface,  SHRCM.G08161.  c,  dorsal  view  showing  ornamentation,  b-b,  line  of  cross  section, 
SHRCM.G08162.  d,  immature  specimen,  part  superimposed  on  to  counterpart  to  show  dorsal  side  with  details 
of  ornamentation,  and  ventral  side  with  details  of  posterior  under  surface,  NM  W88.32G.  1 a/b.  Abbreviations : 
dr,  developing  region;  por,  pre-oral  rim/maxillary  brim;  pos,  pre-oral  surface;  pow,  pre-oral  wall. 


irregularly  shaped  tubercles  running  from  the  tip  to  the  branchial  opening  and  dividing  the  dorsal  side.  On  the 
antero-dorsal  side  and  edge,  the  tubercles  have  a tendency  to  form  weak  ornamental  units  and  run  in  rows 
around  the  postero-dorsal  and  ventral  sides.  Towards  the  tip,  they  become  elongated  and  reach  up  to  1 mm 
in  thickness.  The  lateral  vane  is  usually  terminated  at  the  back  by  a cyclomoriform  unit,  which  forms  a 
horizontal  flange  (see  Text-fig.  6a)  measuring  10  mm  long  x 5 mm  wide  on  SHRCM.G08153  and 
SHRCM.G08154.  Where  the  branchial-cornual  plate  slopes  upwards  to  meet  the  lateral  edge  of  the  dorsal  disc, 
it  is  composed  of  a longitudinal  row  of  units  (Text-fig.  7b,e).  These  cover  the  dorsal  side  of  the  branchial  duct, 
encircle  the  medially  facing  side  of  the  branchial  opening,  and  are  terminated  posteriorly  by  a large  unit  (Text- 
fig.  6a, d).  They  often  leave  internal  impressions  marking  their  edges  (PI.  3,  fig.  4;  Text-fig.  6b).  On  the  basal 
laminated  layer  of  SHRCM.G08155  growth  ridges  run  longitudinally  between  the  units  and  the  lateral  keel 
(Text-fig.  6 e). 

The  ornament  on  the  ventral  side  of  the  branchio-cornual  plate  (Text-fig.  6c)  curves  transversely  from  the 
front  of  the  lateral  vane,  to  run  parallel  with  the  ventral  edge,  which  is  concave  to  accommodate  the  lateral 
edge  of  the  ventral  disc.  A zone  of  growth  runs  parallel  with  the  ventral  and  dorsal  anterior  edges,  which  are 
angled  to  match  the  ventro-posterior  edge  of  the  orbital  plate  and  the  posterior  edge  of  the  lateral  plate. 

Three  elongate  and  approximately  diamond-shaped  plates  (PI.  3,  figs  1 and  2;  Text-fig.  6f,h,i)  appear  to 
represent  juvenile  branchio-cornual  plates.  Their  sizes  are:  SHRCM.G08157  33  mm  longxl3mm  wide; 
SHRCM.G08156  26  mm  long  x 10  mm  wide;  SHRCM.G081 58  21  mm  long  x 8 mm  wide.  Each  is  bowed  along 
its  length,  angled  at  its  front,  and  tapered  towards  the  back,  where  a region  about  5 mm  long  projects  about 
2-5  mm  from  the  lateral  side  of  the  plate.  This  apparently  represents  the  developing  lateral  vane. 

SE1RCM.G08156  has  been  prepared  to  show  typical  P.  symondsi  tubercles  in  various  stages  of  eruption  and 
development  (Text-fig.  6 f).  The  inner  surface  of  SHRCM.G08158,  shows  recently  enclosed  spaces  which  form 
blister-like  regions  with  centrally-placed  pores.  A 1-2  mm  wide  margin  around  the  edges  is  a maze  of  openings 
surrounded  by  enclosing  basal  laminated  growth  (PI.  3,  fig.  3;  Text-fig.  6 1).  The  longitudinal  row  of  units  is 


explanation  of  plate  2 

Figs  1-6.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland.  1,  SHRCM.G08147/2,  right 
orbital  plate,  mostly  internal  view.  2,  SHRCM.G08140,  immature  dorsal  disc,  in  part  external  mould.  3, 
SHRCM.G08250,  cast  of  pineal  plate.  4,  SHRCM.G08160,  cast  of  ventral  surface  of  rostrum.  5, 
NMW88.32G.lu,  cast  of  ventral  surface  of  immature  rostrum.  6,  SHRCM.G08162/1,  cast  of  dorsal  surface 
of  rostrum.  All  x 4. 


PLATE  2 


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410 


PALAEONTOLOGY,  VOLUME  34 


superimposed  on  counterpart,  showing  sensory  canal  system,  SHRCM.G08152/1-2.  b,  right  plate,  dorsal  side 
showing  ornamentation,  with  dorsal  half  of  counterpart  showing  inner  surface,  SHRCM.G08153/1-2.  c,  right 
plate,  ventral  side  with  part  superimposed  on  counterpart,  SHRCM.G08154/1-2.  d,  left  plate,  lateral  view 
showing  details  of  worn  ornament,  BMNH31146.  e,  fragmentary  right  plate,  lateral  view  of  inner  surface, 
SHRCM.G08155.  f,g,  juvenile  right  plate;  f,  ventral  view  with  detail  of  ornamentation;  G,  lateral  view;  a-a, 
line  of  cross  section.  SHRCM.G08156.  H,  juvenile  right  plate,  lateral  view,  SHRCM.G08157.  i,  juvenile  left 
plate,  showing  inner  surface,  SHRCM.G08158/1-2.  j,  ‘adolescent'  left  plate,  lateral  view,  mainly  internal, 
SHRCM.G08159.  Abbreviations:  b',  bite;  bpu,  large  posterior  unit;  brd,  branchial  duct;  bro,  branchial 
opening;  grd,  growth  ridges;  hf.  horizontal  flange;  im,  inset  margin;  imu,  internal  impressions  of  units;  ldc, 
lateral  dorsal  longitudinal  canals;  lk,  lateral  keel;  lv,  lateral  vane;  vp,  vascular  pores. 


missing  from  these  plates,  and  they  are  much  flatter  than  the  adult  branchio-cornual  plates.  Nevertheless,  their 
branchial  ducts  run  their  entire  length,  which  shows  that  the  branchial  openings  were  posteriorly  placed  and 
not  enclosed.  Although  the  superficial  layer  was  destroyed  during  preparation,  the  lateral  side  of 
SHRCM.G08157  is  4 mm  in  thickness,  corresponding  to  the  enlargement  of  the  lateral  keel. 

SHRCM.G08159  (Text-fig.  6 j)  is  an  internal  mould  of  an  early  stage  of  development  of  a branchio-cornual 


EXPLANATION  OF  PLATE  3 

Figs  1-5.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland,  branchio-cornual  plates. 
1 , SHRCM.G08 158/1 , cast  of  inner  surface  of  immature  left  plate,  x 4.  2,  SHRCM.G081 56,  cast  of  ventral 
surface  of  immature  right  plate,  x4.  3,  detail  of  1,  x 10.  4,  SHRCM.G081 53/1,  dorsal  view  of  right  plate, 
in  part  internal  mould,  x 2.  5,  SHRCM.G08152/2,  dorsal  view  of  external  mould  of  left  plate,  x2. 


PLATE  3 


mi in 


TARRANT,  Phialaspis  symondsi 


412 


PALAEONTOLOGY,  VOLUME  34 


i i 

20mm 


epm 


text-fig.  7.  Phialaspis  symondsi  (Lankester),  dorsal  shield,  SHRCM.G08164/1-2.  a,  internal  plan  view,  with 
detail  of  anterior,  b,  part  superimposed  on  to  counterpart  to  show  ornamentation,  a-a,  line  of  cross  section. 
Abbreviations : epm,  estimated  position  of  posterior  margin ; igbcp,  regions  of  intergrowth  between  dorsal  disc 
and  branchio-cornual  plate;  igorp,  regions  of  intergrowth  between  dorsal  disc  and  orbital  plate;  igpip,  regions 
of  intergrowth  between  dorsal  disc  and  pineal  plate;  ltc,  lateral  transverse  commissure;  mdc,  medial  dorsal 

longitudinal  canal;  su,  sutures. 


plate.  Although  the  whole  plate  only  measures  30  mm  long,  its  branchial  duct  is  strongly  dorso-ventrally  folded 
as  in  adult  specimens.  A cross-section  at  the  front  shows  all  levels  of  the  exoskeleton  to  be  present.  The  large 
dorsal  posterior  unit  is  present,  and  is  estimated  to  be  two-thirds  the  size  of  the  equivalent  area  on  the  adult 
plates.  A depressed  margin,  1-2  mm  wide,  around  its  dorsal  and  posterior  edges,  and  running  along  the  dorsal 
side  of  the  branchial  duct,  appears  to  show  regions  of  active  outward  growth.  An  open-ended  notch  2 mm  wide 
dissects  the  margin  at  the  anterior  of  the  posterior  unit  and  appears  to  represent  the  start  of  the  enclosure  of 
the  branchial  opening. 

An  incomplete  dorsal  headshield,  SHRCM.G08164  (PI.  4,  figs  1 and  2;  Text-fig.  7),  which  is  somewhat 
distorted  by  compression,  consists  of  the  dorsal  disc,  the  inner  halves  of  the  branchio-cornual  plates,  the  back 
of  the  pineal  plate  and  the  dorso-posterior  part  of  the  orbital  plates,  with  the  omission  of  the  pineal,  orbital, 
and  branchial  openings.  In  contrast  to  the  tubercles  found  in  the  regions  of  adult  growth  of  isolated  dorsal 
discs,  the  tubercles  in  the  regions  of  adult  growth  of  SHRCM.G08164  vary  considerably  in  size  and  shape 
(Text-fig.  7 b).  Prior  to  the  formation  of  peripheral  adult  growth,  the  dorsal  disc  acquired  the  longitudinal  units 
of  the  branchio-cornual  plates,  then  fused  with  the  back  of  the  pineal  plate  and  the  dorso-posterior  part  of  the 
orbital  plates,  where  sutures  can  be  observed  on  the  inner  surface  (Text-fig.  7 a).  As  there  is  no  evidence  of  adult 
growth  on  the  dorsal  edges  of  the  branchio-cornual  plates  of  P.  symondsi , it  appears  that  during  adulthood, 
the  dorsal  disc  SHRCM.G08164  encroached  and  intergrew  with  the  longitudinal  units  of  the  branchio-cornual 
plates.  Due  to  a large  range  in  size,  it  would  appear  that  the  pineal  and  orbital  plates  of  P.  symondsi  were 
capable  of  adult  growth,  and  probably  on  SHRCM.G08164,  they  contributed  to  the  intergrowth  and  kept  the 
encroachment  of  the  dorsal  disc  in  check. 

In  the  ventral  discs  (Text-fig.  8),  the  flat  central  area  stands  proud  by  1-2  mm  and  its  surface  consists  of  a 


TARRANT:  LOWER  DEVONIAN  OSTRACODER  M 413 


text-fig.  8.  Phialaspis  symondsi  (Lankester),  ventral  disc,  a,  internal  view,  showing  attached  posterior  units, 
SHRCM.G08165.  b,  external  view  showing  sensory  canal  system,  a-a,  b-b,  lines  of  cross  section, 
SHRCM.G08166/1-2.  c.  immature  plate,  a-a,  line  of  cross  section,  SHRCM.G08167/1-2.  d,  detail  of 
ornament  on  left  anterior  corner,  SHRCM.G08168.  e,  detail  of  worn  ornament  on  the  anterior,  BMNH46712. 
f,  abraded  posterior,  SHRCM.G08169;  G,  transverse  view  across  midline,  showing  part  of  abnormal 
longitudinal  rows  of  units,  SHRCM.G08170.  h,  part  of  left  side  showing  longitudinal  rows  of  units, 
SHRCM.G08171/  i,  specimen  developed  to  show  sensory  canal  system,  SHRCM.G08171.  Abbreviations:  b , 
bite;  hf,  healed  fracture;  lpu,  lateral  posterior  unit;  lru,  longitudinal  row  of  units;  mpu,  medial  posterior  unit; 
poc,  post-oral  sensory  canal;  sea,  smooth  central  area;  sp,  sensory  pores;  vie,  ventral  longitudinal  sensory 

canal. 


smooth  sheet  of  dentine.  Regardless  of  the  size  of  the  rest  of  the  disc,  it  varies  considerably  in  size  and 
proportions,  ranging  in  length  from  31  to  60  mm,  and  in  width  from  1 1 mm  to  an  estimated  and  exceptional 
40  mm  in  BU759.  The  posterior  edge  in  SHRCM.G08169  is  worn,  and  the  adjacent  tubercles  are  abraded  and 
merge  with  the  smooth  dentine  (Text-fig.  8 f). 

The  tubercles  of  the  ventral  disc,  in  contrast  to  those  of  the  dorsal  disc,  are  usually  of  a similar  size  and 
normally  moderately  elongated.  Tarlo  (1962)  recognised  that  bands  of  ornamented  growth  joined  each  lateral 
side  of  the  smooth  central  region  to  a row  of  longitudinally  running  units.  These  units  are  cyclomoriform  and 
raised  centrally.  Although  internal  impressions  marking  their  edges  are  sometimes  observed,  they  often 
protrude  internally.  There  are  usually  five  or  more  a side,  and  in  SHRCM.G08170  there  are  two  rows  crowded 
together  on  each  side  (Text-fig.  8g).  A single  unit  can  range  in  size  from  4-15  mm  long  x 4-10  mm  wide. 

In  certain  specimens  of  ventral  discs,  the  ornament  at  the  front  runs  horizontally,  matching  underlying 
growth  ridges.  In  other  cases,  it  runs  at  right  angles  to  the  growth  ridges,  before  curving  round  the  anterior 
edges  of  the  longitudinal  rows  of  units,  where  on  SHRCM.G08168  the  tubercles  join  together  to  become 


414 


PALAEONTOLOGY,  VOLUME  34 


elongated  (Text-fig.  8d).  This  region  on  BMNH46712  has  broadened  and  abraded  tubercles  (Text-fig.  8e).  The 
flow  of  ornament  running  from  the  posterior  of  the  smooth  central  region  is  also  variable,  but  does  not  overlie 
any  growth  ridges. 

Three  units  forming  the  posterior  end  of  the  ventral  disc  and  uniting  the  two  longitudinal  rows  of  units  are 
only  observed  clearly  as  internal  impressions  on  SHRCM.G08165  (PI.  4,  fig.  4;  Text-fig.  8a),  and  probably 
contacted  the  antero-ventral  ridge  scale  and  the  two  antero-ventral  scales.  The  medial  posterior  unit  measures 
7 mm  long  x 9 mm  wide  and  the  two  lateral  posterior  units  both  measure  1 1 mm  long  x 17  mm  wide.  As  they 
flatten  out  at  an  angle  from  the  vaulted  posterior  end  of  the  disc,  it  is  likely  that  they  would  have  been  lost 
after  death,  and  were  seemingly  often  independent  of  the  disc  in  the  younger  animals. 

Four  specimens  of  immature  ventral  discs  are  represented  by  smooth  areas  with  narrow  ornamented  margins 
and  no  attached  units.  Each  central  area  is  of  adult  proportions,  but  as  observed  on  SHRCM.G08167  (PI.  4, 
fig.  3;  Text-fig.  8 c),  it  rests  only  slightly  proud  of  the  rest  of  the  disc.  The  anterior  and  posterior  ends  of  the 
discs  are  observed  to  be  flattened  internally  by  a thickening  of  the  cancellous  layer. 

A specimen  (BU77)  described  by  Wills  (1935)  as  cf.  Ctenaspis , is  actually  a fragmentary  ventral  disc  from 
P.  symondsi.  With  the  exception  of  a small  region  of  smooth  dentine  measuring  1 x 2 mm,  the  superficial  layer 
is  missing,  leaving  the  cancellae  exposed. 

As  White  (1946)  found  on  T.  pococki , P.  symondsi  had  two  lateral  plates.  The  lateral  plate  is  approximately 
triangular  in  shape  (PI.  5,  figs  2 and  5;  Text-fig.  9a-d).  It  is  widest  at  its  anterior  end,  and  tapers  towards  its 
posterior  edge  where  it  met  the  branchio-cornual  plate.  The  plate  is  folded,  forming  anterior,  lateral,  and 
ventral  sides,  and  it  is  deepest  at  their  junction.  The  bulk  of  the  plate  is  ventral  in  position,  where  it  is  flattest. 
One  edge  is  concave  to  embrace  half  of  the  anterior  edge  of  the  ventral  disc.  On  the  opposite  edge,  the  plate 
is  folded  longitudinally  at  an  angle  of  60-90°,  to  form  the  3-4  mm  wide  laterally  facing  side,  which  is  angled 
to  meet  the  ventral  edge  of  the  orbital  plate.  The  anteriorly  facing  side  folds  inwards  at  between  20°  and  50° 
from  the  main  body  of  the  plate.  It  is  cradled  by  a concave  region,  which  at  one  end  forms  a projection  that 
would  have  met  the  postero-ventral  part  of  the  rostrum,  and  at  the  other  end  forms  either  a truncated  mesial 
edge,  or  a post-oral  process  (Text-fig.  9a,c),  The  post-oral  process  is  partly  square  in  outline,  flattened  at  its 
free  end,  and  measures  about  5 mm  long  x 10  mm  wide.  It  is  too  short  to  occupy  the  space  between  the  lateral 
plates,  the  front  of  the  ventral  disc,  and  the  oral  region,  and  must  therefore  have  been  paired. 

About  one  third  of  the  lateral  plates  collected  from  Devil’s  Hole  have  post-oral  processes,  but  the  rest  show 
no  sign  of  this  structure  and  must  have  possessed  separate  post-oral  plates.  Older  animals  may  have  fused 
plates.  Although  the  lateral  plate,  SHRCM.G08174  (PI.  5,  fig.  5;  Text-fig.  9d),  has  an  exoskeleton  of  adult 
thickness,  it  measures  19  mm  long  x 10  mm  wide,  and  is  so  small  that  it  must  represent  an  immature  plate,  yet 
it  possesses  a well-formed  post-oral  process. 

The  ornament  on  the  lateral  plates  is  cyclomoriform,  and  the  post-oral  process  was  formed  from  a separate 
cyclomoriform  unit.  The  tubercles  in  some  specimens  (Text-fig.  9 a)  are  enlarged  and  joined  together,  and 
tubercles  occasionally  run  at  right  angles  to  the  main  ornamental  direction. 

Because  of  their  large  size,  it  seems  that  two  anterior  lateral  plates  and  one  median  oral  plate  were  the  full 
complement  of  oral  plates  present  in  P.  symondsi. 

The  posterior  end  of  the  median  oral  plate  seems  to  have  been  as  wide,  if  not  slightly  wider  than  the  posterior 
margin  of  the  oral  cavity,  and  somewhat  longer  than  the  length  of  the  oral  cavity.  Therefore  it  would  appear 
to  have  rested  inside  the  mouth,  where,  laterally  and  posteriorly,  it  was  overlapped  by  the  anterior  lateral 
plates.  It  ranges  in  width  from  16  to  11  mm,  in  length  from  14  to  12  mm,  and  is  about  6 mm  high.  It  is 
scoop-shaped,  and  is  ornamented  on  its  outer  side  and  smooth  on  its  inner  side  and  edges  (PI.  5,  fig.  4;  Text- 
fig.  9e,f).  The  inner  side  (Text-fig.  9 f)  has  an  elongated  and  gently  convex  central  area,  which  strengthens  and 
widens  towards  the  back.  The  inner  side  behind  the  edge  turns  outwards  to  form  a narrow  lip,  which  is  matched 
by  a thickening  of  the  exoskeleton.  On  the  outside  the  tubercles  are  small  and  narrow  and  they  generally  run 
longitudinally,  although  they  sometimes  curve  and  run  at  right  angles  to  the  main  direction.  The  ornament  is 
abraded  in  places,  in  particular  on  the  right  lateral  side  of  SHRCM.G08177,  and  there  is  a large  callus  5 mm 


EXPLANATION  OF  PLATE  4 

Figs  1-4.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland.  1 and  2,  SHRCM.G08164/1/2, 
dorsal  headshield,  dorsal  views  of  internal  mould  and  silicon  rubber  impression  of  external  surface, 
respectively.  3 and  4,  ventral  discs;  3,  SHRCM.G08167/1,  external  mould  of  immature  disc;  4, 
SHRCM.G08165,  internal  view  of  cast.  All  x 1. 


PLATE  4 


TARRANT,  Phialaspis  symondsi 


416 


PALAEONTOLOGY,  VOLUME  34 


10mm 


text-fig.  9.  Phialaspis  symondsi  (Lankester),  a-d,  lateral  plates;  a,  external  view  of  right  plate,  showing 
ornamentation,  a-a,  b-b,  lines  of  cross  section,  SHRCM.G08173/1-2;  b,  internal  view  of  left  plate,  without 
post-oral  process,  SHRCM.G08176/1-2;  c,  right  plate  developed  to  show  sensory  canal  system, 
SHRCM.G08175;  d,  internal  view  of  immature  left  plate,  SHRCM.G08174.  e-h,  oral  plates;  e,  internal  view 
of  median  oral  plate;  F,  ditto,  external  view,  a-a,  b-b,  lines  of  cross  section,  SHRCM.G08177/1-2;  g,  right 
posterolateral  corner  of  median  oral  plate,  showing  region  of  abrasion,  SHRCM.G08178.  H,  external  view  of 
left  anterior  lateral  plate,  c-c,  line  of  cross  section,  SHRCM.G08179.  i-u,  scales;  i-k,  dorsal  ridge  scale, 
SHRCM.G08180/1-2;  I,  external  view;  j,  internal  view;  K,  lateral  view;  l-m,  ventral  ridge  scale, 
SHRCM.G08181 ; l,  external  view;  m,  lateral  view;  n,o,  internal  views  of  ventral  ridge  scales,  a-a,  line  of  cross 
section,  SHRCM.G08182,  08183;  p,q,  large  flank  scales,  b-b  line  of  cross  section,  SHRCM.G08190,  08191; 
R,  external  view  of  flank  scale,  SHRCM.G08185 ; s,  internal  view  of  flank  scale,  SHRCM.G08184;  t,  ?caudal 
scale,  SHRCM.G08187;  u,  incomplete  ?ventral  lateral  scale,  c-c,  line  of  cross  section,  SHRCM.G08189. 
Abbreviations:  as,  anterior  side;  bsp,  broken  spine;  ca,  calus;  cn,  concaved  notch;  cr,  convexed  central  area; 
esc,  exit  pores  for  sensory  canals;  fo,  foramina;  poc,  post-oral  sensory  canal;  pop,  post-oral  process;  vie, 

ventral  longitudinal  sensory  canal. 


EXPLANATION  OF  PLATE  5 

Fig.  1.  Toombsaspis  pococki  (White),  lower  Devonian,  Welsh  Borderland,  BU.2098/1,  cast  of  dorsal 
headshield,  x 4. 

Figs  2-5.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland.  2,  SHRCM.G08179,  cast  of 
right  anterior  lateral  plate.  3,  SF1RCM.G08173/1,  cast  of  right  lateral  plate.  4,  SF1RCM.G08177/1,  cast  of 
median  oral  plate.  5,  SHRCM.G08174,  internal  view  of  cast  of  immature  left  lateral  plate.  All  x4. 


PLATE  5 


TARRANT,  Toombsaspis  pococki , Phialaspis  symondsi 


418 


PALAEONTOLOGY,  VOLUME  34 


long  and  2 mm  thick,  at  the  posterior  end  of  the  right  lateral  side  in  SHRCM.G08178  (Text-fig.  9g).  The  worst 
of  these  abrasions  appear  to  have  been  caused  by  friction  against  the  anterior  lateral  plates. 

The  anterior  lateral  plate  is  represented  by  one  specimen  SHRCM.G08179  (PI.  5,  fig.  2;  Text-fig.  9h). 
Although  much  larger,  this  resembles  BMNH24788,  a specimen  that  White  (1946)  described  as  possibly  an 
anterior  lateral  plate  from  T.  pococki.  It  measures  14  x 10  mm  and  is  semicircular  and  bowed  in  shape.  It  rises 
to  4 mm,  around  a concave  notch  on  one  edge,  and  flattens  towards  the  opposite  edge.  The  inner  surface  is 
smooth,  and  the  tubercles  on  the  outer  surface  are  progressively  more  abraded  towards  the  raised  region,  where 
they  are  missing.  The  exoskeleton  is  pierced  by  foramina,  which  radiate  in  three  rows  around  the  concave 
notch.  The  largest  of  these  foramina  are  ovate,  1 mm  in  diameter,  and  are  angled  to  point  towards  the  flattened 
part  of  the  plate.  These  oral  plates  presumably  lay  freely  edge  to  edge,  with  their  raised  concave  notches  lying 
antero-laterally  and  facing  the  anterior  edges  of  the  lateral  plates.  This  supposition  is  based  on  the  shape  of 
the  oral  cavity,  as  manifested  by  its  surrounding  plates,  and  the  shape  and  dimensions  of  the  anterior  lateral 
plates. 

As  White  (1946)  observed  with  Phialaspis , the  sensory  canal  system  was  variable,  irregular,  often 
asymmetrical,  and  in  P.  symondsi  sometimes  segmented.  It  also  ranged  considerably  in  depth  within  the 
exoskeleton.  Grooves  underlying  sensory  canals  can  be  seen  with  varying  clarity  on  the  internal  moulds.  These 
are  not  to  be  confused  with  impressions  marking  the  edges  of  units  (Text-figs  2b  and  6b).  In  places,  rows  of 
pores  can  be  traced  across  the  external  surface  of  several  specimens  (Text-figs  2 a,  4c,  8i). 

White  (1946)  considered  that  T.  pococki  had  paired,  medial  and  lateral  dorsal  longitudinal  canals  joined  by 
medial  and  lateral  transverse  commissures,  although  he  suggested  that  the  lateral  dorsal  longitudinal  canals 
may  have  been  incomplete  or  sometimes  absent.  It  is  possible  that  the  lateral  transverse  commissures  were 
occasionally  partly  joined  at  their  lateral  extremities  by  a longitudinal  canal,  but  I have  found  no  evidence  in 
T.  pococki  or  P.  symondsi  to  support  the  presence  of  lateral  dorsal  longitudinal  canals  in  the  positions  suggested 
by  White.  Instead,  it  would  appear  that  they  were  isolated,  except  at  their  anterior  end,  from  the  lateral 
transverse  commissures,  and  are  represented  by  the  branchial  canals  described  in  T.  pococki  by  White  (1946). 
In  P.  symondsi , these  run  under  the  longitudinal  rows  of  units  on  the  branchio-cornual  plates  (Text-fig.  6 a). 

The  inter-orbital  canal  forms  a crescent  on  the  pineal  plate  encircling  the  posterior  and  lateral  sides  of  the 
pineal  organ  (Text-fig.  4e,f).  It  joins  the  medial  dorsal  longitudinal  canals.  On  each  side,  it  meets  a supra- 
orbital canal  and  a transverse  canal  which  run  on  to  the  orbital  plate  (Text-figs  4 and  13).  and  join  before 
meeting  the  circum-orbital  canal  (Text-figs  4a-c,  13,  14).  The  circum-orbital  canal  completely  encircles  the 
orbit.  Radiating  from  it,  are  the  anterior  lateral  transverse  commissure,  the  lateral  dorsal  longitudinal  canal, 
and  a canal  which  runs  ventrally  on  to  the  lateral  plate  (Text-figs  4c  and  9c)  and  joins  the  post-oral  and  ventral 
longitudinal  canals.  White  (1946)  observed  no  post-oral  canals  in  the  P.  symondsi  ventral  discs  he  studied.  This 
is  often  the  case,  as  the  post-oral  canals  were  frequently  short  and  confined  to  the  lateral  plates,  although 
sometimes  they  were  present  on  the  ventral  discs  and  V-shaped  (Text-fig.  8i).  As  White  noted,  the  ventral 
longitudinal  canals  underlaid  the  longitudinal  rows  of  units  and  were  varied,  often  segmented  posteriorly 
(Text-fig.  8b,i). 

Because  specimens  of  the  rostrum  and  anterior  lateral  plates  are  rare,  no  attempt  has  been  made  to  expose 
possible  sensory  canals  in  these  regions.  However,  no  evidence  has  been  found  for  sensory  canals  either  leading 
to  or  on  them,  and  it  would  appear  that  these  were  either  absent  or  not  linked  to  the  main  sensory  canal  system. 

A variety  of  scales  has  been  found,  scattered  thinly  among  the  larger  P.  symondsi  plates.  Most  are 
superficially  pteraspid-like,  but  the  anterior  flank  scales  are  proportionally  much  larger. 

Dorsal  ridge  scales  measure  8 mm  long  x 5 mm  wide  to  17  mm  long  x 16  mm  wide.  They  are  rounded  and 
flattened  anteriorly  and  rise  towards  the  back  to  create  an  overlapping  region  where,  although  broken  on 
SHRCM.G08177  (Text-fig.  9i-k),  they  appear  to  have  been  crowned  with  a low  spine.  The  undersurface  is 
gently  dished,  with  two  exit  pores  near  the  back  for  the  medial  dorsal  longitudinal  sensory  canals.  The  ventral 
ridge  scales  range  from  8 mm  long  x 4 mm  wide  to  over  17  mm  long  x 9 mm  wide.  They  are  elongated  and 
spinate  (Text-fig.  9l-o),  with  a small  anterior  region  of  attachment  angled  at  about  60°  from  a hollowed, 
posterior  undersurface.  This  shows  that  they  were  considerably  raised  and  possibly,  overlapped  strongly. 

Several  flank  scales,  including  two  very  large  specimens  (Text-fig.  9p,q),  are  asymmetrical  and  somewhat 
flattened,  and  range  in  size  from  11x11  mm  to  16x18  mm.  A depressed  region  running  across  one  anterior 
corner  indicates  an  overlapped  region,  the  majority  of  flank  scales  collected  are  smaller,  ranging  from  7 mm 
long  x 8 mm  wide  to  10  mm  longxl3mm  wide.  They  are  diamond  shaped  (Text-fig.  9r,s)  and  folded 
longitudinally  to  leave  a slightly  raised  posterior  and  a somewhat  flattened  anterior  corner,  suggesting  regions 
of  overlap.  Several  possibly  incomplete,  anterior  ventral  lateral  scales  are  asymmetrical,  elongated,  and  folded 
longitudinally,  to  present  two  unequal  sides  (Text-fig.  9u).  They  range  from  15  mm  long  x 10  mm  wide  to  over 
15  mm  long  x 15  mm  wide.  Two  small  crescent  scales  are  possibly  caudal  in  origin  (Text-fig.  9t). 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


419 


text-fig.  10.  Phialaspis  symondsi  (Lankester),  regions  of  injury,  a-d,  on  anterior  parts  of  ventral  discs;  a,b,c, 
SHRCM.G3802/G08168/G08195.1-2  respectively;  d,  BGSGSM31380.  E,  deformed  lateral  plate, 
SHRCM.G08196.  F,  scar  on  longitudinal  unit  of  ventral  disc,  SHRCM.G38197.  Abbreviations:  as,  anterior 
side;  dar,  damaged  region;  der,  deformed  region;  hf,  healed  fracture;  sea,  scar;  vi,  vascular  impressions. 


Injuries  and  predation  scars.  White  (1946,  figs  53  and  54)  observed  the  impression  of  a healed  fracture  in  the 
left  anterior  corner  of  the  P.  symondsi  ventral  disc  BMNH194.  The  injury  had  healed  perfectly  showing,  as 
White  suggested,  that  the  injury  must  have  happened  some  time  before  the  animal’s  death.  Of  ventral  discs 
collected  from  Devil’s  Hole  which  were  complete  enough  to  observe  the  anterior  portion,  44%  showed  injuries 
like  the  fracture  described  by  White  (PI.  6,  fig.  5),  which  suggests  a common  specific  kind  of  injury.  Although 
many  of  these  injuries  consist  of  healed  fractures,  on  several  specimens  one  or  both  antero-lateral  corners 
are  missing  (see  PI.  6,  figs  3-5;  Text-fig.  10  a-d).  This  shows  a failure  of  the  broken  components  to  knit.  In 
certain  individuals  (Text-fig.  10  b),  narrow  regions  of  outward  growth,  running  across  these  more  severe 
injuries,  show  that  the  animals  died  soon  after  their  occurrence.  In  contrast,  other  specimens  (Text-fig.  10c,d) 
show  a reasonable  amount  of  post-injury  plate  growth.  These  injuries  are  extreme  in  the  type  specimen 
BGS(GSM)31380  (Text-fig.  10d),  where  both  antero-lateral  corners  and  a medially  placed  segment  at  the  front 
are  missing.  A deformed,  right  lateral  plate  (Text-fig.  1 0 e)  has  the  usual  concave  contact  edge  with  the  ventral 
disc  straight.  This  may  correspond  to  the  injuries  on  the  ventral  discs. 

A ventral  disc  SHRCM.G08170  and  a branchio-cornual  plate  SHRCM.G08154  (Text-figs  6g  and  8c)  are 
both  pierced  by  a 1-5  mm  wide  circular  hole.  Tarlo  (1966)  observed  a hole  of  a similar  kind  in  the  branchial 
plate  of  Psammosteus  praecursor,  which  he  considered  was  caused  by  a crossopterygian  bite.  It  is  possible  that 
the  holes  in  P.  symondsi  may  have  been  caused  by  the  bite  of  a large  ischnaeanthid.  Much  the  same  may  apply 
to  a well-healed,  semi-circular  scar  on  a longitudinal  unit  of  the  ventral  disc  SHRCM.G38197  (Text-fig.  1 0 f). 

Remarks.  Dineley  ( 1964)  described  a dorsal  disc,  NMC10373,  from  the  Knoydart  Formation,  Nova 
Scotia,  Canada,  which  he  considered  was  sufficiently  close  to  the  specimens  from  the  Anglo-Welsh 
region  to  call  it  Traquairaspis  symondsi.  However,  until  more  Nova  Scotian  material  is  described, 
it  is  unjustifiable  to  consider  that  this  specimen  belongs  to  P.  symondsi , and  it  is  probably  best 
referred  to  as  Phialaspis  sp. 


Genus  toombsaspis  gen.  nov. 


Etymology.  In  remembrance  of  the  late  Mr  H.  A.  Toombs,  and  asp  is,  Greek,  shield. 


420 


PALAEONTOLOGY,  VOLUME  34 


Type  species.  Phialaspis  pococki  White,  1946 

Other  species  assigned.  Toombsaspis  sabrinae  (White,  1946) 

Diagnosis.  Small  phialaspidids  with  lateral  keels.  Low  dorsal  vane.  Ventral,  longitudinal 
cyclomoriform  units  against  each  lateral  side  of  ventral,  smooth  central  area.  Ornament  of  stellated, 
equilateral  and  elongated  tubercles  divided  by  fine  ridges.  Ventral  disc  tubercles  elongated  on  sides, 
in  stacked  V-shapes  at  back. 


Toombsaspis  pococki  (White,  1946) 

Plate  5,  fig.  I ; Text-figs  1,11,  14c-g,  15h;  Table  2 

1946  Phialaspis  pococki  White,  pp.  217-229,  pi.  12,  fig.  1 ; figs  1,  3-8,  12-19,  22-27,  31-35,  39,  40M4, 
55. 

1948  Traquairaspis  pococki  (White);  White  and  Toombs,  p.  55,  pi.  7,  fig.  1. 

Holotype.  BMNH24511  dorsal  disc. 

Horizon  and  localities.  Upper  Silurian/Lower  Devonian,  Upper  Downton  Group.  The  Lower  Old  Red 
Sandstone  of  the  Anglo-Welsh  region  (Text-fig.  1). 


table  2.  Maximum  dimensions  of  Toombsaspis  pococki  plates  in  millimetres.  Abbreviation : pop,  post-oral 
process. 


Range 

Average 

Length 

Width 

Ratio  of  width 
to  length 

Length 

Width 

Ratio  of 
width 
to  length 

Dorsal  discs 

22-31 

22-29 

0-73-1  00 

28 

25 

0-89 

Orbital  plates 

11-13 

7 

0-53-0-63 

12 

7 

0-58 

Pineal  plates 

5-7 

6-7 

1-00-1-20 

6 

6 

1-00 

Rostrums 

2 

9 

4-5 

Branchio-cornuals 

25-29 

6-7 

0-24 

27 

6-5 

0-24 

Ventral  discs 

32-39 

18-25 

0-53-0-69 

35 

22 

0-63 

Lateral  plates  4-  pop 

8 

7 

0-87 

Lateral  plates  — pop 

14 

7 

0-50 

Curvital  dimensions 

Dorsal  discs 

22-31 

24-31 

0.89-1.09 

28 

27 

0-96 

Ventral  discs 

33^40 

24-30 

0-68-0-80 

36 

28 

0-77 

Referred  material.  Specimens  housed  in  the  BMNH  (especially  BMNH24751  and  BMNH24568-9)  and  BU 
(especially  BU2096-2102). 

Diagnosis.  Dorsal  and  ventral  discs  approximately  evenly  vaulted.  Dorsal  vane  small  with  one 
cyclomoriform  unit,  dorsal  median  keel  with  two.  Rostrum  short.  Dorsal  disc  tubercles  long  on 
units,  equilateral  on  periphery. 

Description.  Internal  impressions  marking  the  edges  of  cyclomoriform  units  are  not  usually  found,  although 
White  (1946)  observed  internal  impressions  in  the  dorsal  disc  BMNH24512,  which  he  considered  were  left  by 
sensory  canals.  These  appear  to  resemble  the  internal  impressions  marking  the  edges  of  units  in  the  dorsal  discs 
of  P.  symondsi. 


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421 


text-fig.  1 1 Toombsaspis  pococki  (White),  a,  pineal  plate  fused  to  orbital  plate,  BMNH24568-9.  b,  dorsal 
view  of  rostral  plate,  BMNH24751.  c,  ditto,  anterior  view,  with  detail  of  tip  ornamentation,  d,  right  lateral 
plate,  a-a,  b-b,  lines  of  cross  section,  BU2097.  e,  internal  view  of  left  anterior  side  of  dorsal  disc  showing 
sensory  canals,  BU2100o.  f,  fragmentary  headshield,  showing  left  orbital  plate,  and  part  of  pineal  plate  and 
dorsal  disc,  BU2098.  G,  right  lateral  plate  showing  sensory  canal  system,  BU481A  h,  internal  view  of 
fragmentary  dorsal  disc  showing  sensory  canals,  BU2101.  Abbreviations:  cor,  circum-orbital  sensory  canal; 
dd,  dorsal  disc;  ?ior,  possible  inter-orbital  sensory  canal;  ltc,  lateral  transverse  sensory  commissures;  mdc, 
medial  dorsal  longitudinal  sensory  canal;  mtc,  medial  transverse  sensory  commissures;  or,  orbital  opening; 
orp,  orbital  plate;  pi,  pineal  opening;  pip,  pineal  plate;  poc,  post-oral  sensory  canal;  vie,  ventral  longitudinal 

sensory  canal. 

The  dorsal  disc  is  similar  in  shape  to  that  of  P.  symondsi  and  two  longitudinal  rows  of  cyclomoriform  units 
are  found  on  each  lateral  side.  The  dorsal  vane  ranges  from  2 to  3 mm  in  height  and  6 to  9 mm  in  length. 

The  orbital  plate  (Text-fig.  11a,f),  which  is  more  gently  curved  than  that  of  P.  symondsi , is  approximately 
ovate  to  diamond  shaped.  The  orbital  opening  ranges  from  1 to  T5  mm,  in  diameter. 

The  pineal  plate  (Text-fig.  1 1 a)  is  triangular  in  shape,  with  the  greatest  width  at  the  posterior  end.  The  pineal 
organ  is  centrally  placed  and  penetrates  the  surface  of  the  plate.  The  ornament  on  both  the  pineal  and  orbital 
plates  is  cyclomoriform,  encircling  the  openings.  BU2098  (PI.  5,  fig.  1 ; Text-fig.  1 1 f)  is  a fragment  of  a dorsal 
headshield  showing  plate  fusion  between  the  dorsal  disc,  left  orbital  plate  and  pineal  plate.  The  pineal  organ 
can  only  be  seen  as  an  internal  impression  on  the  counterpart.  The  orbital  plate  forms  a ridge  at  its  anterior 
edge,  where  it  would  have  met  the  rostrum.  BMNH24568-9  (Text-fig.  1 1 a),  identified  by  White  (1946)  as  an 
orbital  plate,  is  a pineal  plate  fused  to  a right  orbital  plate. 

The  rostrum  BMNH24751  (Text-fig.  1 1 b,c)  was  originally  considered  to  have  been  a pineal  plate  (White 
1946).  It  is  proportionally  much  shorter  than  the  immature  P.  symondsi  rostrum,  and  more  closely  resembles 
that  of  ITraquairaspis  adunata  Dineley  and  Loeffler,  1976,  with  elongated  tubercles  running  in  rows  across  its 
anterior  end  and  no  prominent  anterior  apex. 

The  branchio-cornual  plates  (White  1946)  are  proportionally  flatter  and  less  massive  than  those  of  P. 
symondsi  and,  with  no  lateral  vanes,  their  shape  is  generally  closer  to  those  of  Traquairaspis  campbelli.  The 
branchial  opening  is  about  2-5  mm  long  x T5  mm  wide.  It  faces  dorso-laterally  and  is  located  at  about  three- 
fifths  along  the  length  of  the  plate  from  the  front.  The  tubercles  on  the  dorsal  side  tend  to  be  elongate,  and 
a row  of  cyclomoriform  units  overlies  the  lateral  dorsal  longitudinal  sensory  canal. 

Excluding  the  smooth  central  area,  the  ventral  disc  (White  1946)  is  more  vaulted  than  that  of  P.  symondsi 
and,  on  average  it  has  proportionally  larger  central  area.  This  ranges  from  24-27  mm  in  length  to  10  to  12  mm 
in  width.  There  is  a well-defined  row  of  cyclomoriform  units  resting  against  each  side  of  the  central  area,  with 
no  intervening  rows  of  ornamented  growth. 

Although  much  smaller,  the  lateral  plates  (Text-fig.  1 1 d,g)  closely  resemble  those  of  P.  symondsi.  They 


422 


PALAEONTOLOGY,  VOLUME  34 


usually  have  an  attached  post-oral  process.  Nevertheless,  White  (1946)  illustrated  a specimen,  BU4816,  with  the 
post-oral  process  apparently  missing  (Text-fig.  I1g).  White  also  described  a possible  anterior  lateral  plate 
BMNH24788  and  a ridge  scale  BMNH24759.  These  appear  to  be  similar  to  their  corresponding  parts  in  P. 
symondsi. 

The  sensory  canal  system  (Text-figs  1 1 e,f,h  and  14)  is  incompletely  known,  but  appears  to  be  arranged 
similarly  to  that  of  P.  symondsi.  However,  the  dorsal  lateral  transverse  commissures  are  longer,  and  the  inter- 
orbital canal  may  have  extended  into  the  anterior  edge  of  the  dorsal  disc  (Text-fig.  1 1 e). 

Remarks.  T.  pococki , which  retains  more  in  common  with  the  earlier  Traquairaspididae  than  P. 
symondsi , must  be  considered  as  a more  primitive  phialaspidid.  The  specimens  of  a traquair- 
aspidiform  from  the  Red  Bay  Series,  Fraenkelryggen  Formation,  Spitsbergen,  considered  by  Blieck 
(1983)  as  Traquairaspis  cf.  pococki , are  considerably  larger  than  comparable  Anglo-Welsh  T. 
pococki  specimens,  and  are  provisionally  assigned  to  Traquairaspidiform  farm,  gen.  et  sp.  indet. 


Toombsaspis  sabrinae  (White,  1946) 

1946  Phialaspis  pococki  var.  sabrinae  White,  pp.  217-229,  pi.  12,  figs  2^4;  figs  2,  9-1 1,  20,  21,  28-30, 
56. 

Holotype.  S4,  dorsal  disc  (White  1946). 

Type  horizon  and  locality.  Upper  Silurian/Lower  Devonian,  Upper  Downton  Group,  Lower  Old  Red 
Sandstone,  Sharpness,  Gloucestershire,  England  (Text-fig.  1). 

Diagnosis.  Dorsal  disc  approximately  30  mm  long  with  equilateral  tubercles.  Dorsal  vane  large  with 
long  median  tubercle,  continuous  with  dorsal  keel. 


Genus  munchoaspis  nov. 

Etymology.  After  Lake  Muncho,  British  Columbia,  and  as  pis,  Greek,  shield. 

Type  species.  Traquairaspis  denisoni  Dineley,  1964. 

Diagnosis.  Dorsal  disc  approximately  ovate,  attaining  length  of  100  mm,  with  median  keel,  no 
dorsal  vane,  longitudinal  carina  on  each  lateral  side  marking  the  change  in  vaulting  and  double 
cyclomoriform  whorl  on  the  anterior.  Ornament  in  long  fine  ridges  which  run  parallel  to  the  anterior 
and  lateral  edges. 


Munchoaspis  denisoni  (Dineley,  1964)  comb.  nov. 

1964  Traquairaspis  denisoni  Dineley,  pp.  211-215,  pi.  38;  text-figs  1-4. 

Holotype.  NMC 10371,  dorsal  disc. 

Type  horizon  and  locality.  Silurian,  Ludlow/Pridoli,  North  West  of  Lake  Muncho,  British  Columbia,  Canada. 
Diagnosis.  As  for  genus,  the  only  known  species. 

Remarks.  Dineley  (1964)  described  several  incomplete  ventral  discs  from  Canada,  which  he 
considered  were  indistinguishable  in  outline  from  the  British  ones.  The  smooth  ventral  central 
region,  surrounded  by  a gently  sloping  ornamented  brim  with  peripheral  adult  growth  impressions, 
is  a further  typical  phialaspidid  characteristic.  The  early  occurrence  of  this  species  would  appear  to 
strengthen  Dineley  and  Loeffler’s  (1976)  claim  for  a traquairaspidiform  evolutionary  centre  in 
Western  and  Arctic  Canada. 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


423 


Family  traquairaspididae  Kiaer,  1932 
Type  genus.  Traquairaspis  Kiaer,  1932 
Other  genus  assigned.  Rimasventeraspis  nom.  nov. 

Diagnosis.  Ventral  disc  with  narrow  ornamented  margins,  steep  lateral  sides  each  with  a 
longitudinal  row  of  elongated  tubercles  surrounded  by  cyclomorial  fine  ridges.  The  posterior  edge 
sometimes  medially  notched.  Large  ventral  central  area  extending  to  posterior  edge,  either  totally 
smooth,  partly  subdivided,  or  with  irregular  dentine  ridges,  and  on  the  anterior  half,  ventral  medial 
commissures  and  post-oral  sensory  canals. 

Genus  traquairaspis  Kiaer,  1932 

Type  species.  Cyathaspis  campbelli  Traquair,  1913 

Diagnosis.  Dorsal  disc  not  fused  to  adjacent  plates,  ornamented  with  twelve  or  more,  alternating, 
longitudinally  running  rows  of  small  cyclomoriform  units.  Low  dorsal,  postero-medial  keel.  The 
branchio-cornual  plates  narrowly  keeled  behind  the  enclosed  branchial  openings.  Two  distinct  types 
of  ventral  discs;  type  1-  smooth  central  area  extending  the  length  of  plate  (White  1946),  type  2- 
posterior  margin  deeply  notched,  median  region  with  a maze  of  dentine  ridged  units  (Tarlo  1960). 


Traquairaspis  Campbell i (Traquair,  1913) 
Text-fig.  12;  Table  3 

1911  Cyathaspis  n.sp.  Traquair  in  Campbell,  p.  66. 

1913  Cyathaspis  campbelli  Traquair  in  Campbell,  p.  932. 

1932  Traquairaspis  campbelli  (Traquair);  Kiaer,  pp.  25-26,  pi.  11. 
1946  Phialaspis  pococki  subsp.  cowiensis  White,  p.  239,  figs  36-38. 


table  3.  Maximum  dimensions  of  Traquairaspis  campbelli  plates  in  millimetres. 


Average 

Length 

Width 

Ratio  of  width 
to  length 

Dorsal  disc 

39 

27 

0-69 

Branchio-cornual 

39 

1 1 

0-28 

Ventral  disc  type  1 

44 

27 

0 61 

Ventral  disc  type  2 

49 

22 

0-44 

Holotype.  RSM1960.  14.  1. 

Horizon  and  locality.  Upper  Silurian,  Pridoli,  Stonehaven,  Kincardineshire,  Scotland. 

Referred  material.  Specimens  in  the  BMNH. 

Diagnosis.  As  for  genus. 

Description.  The  dorsal  disc  is  four-sided,  vaulted  posteriorly,  flattened  anteriorly,  its  lateral  and  posterior 
edges  are  gently  convex,  its  anterior  edge  is  indented,  and  it  has  slightly  raised  tubercles  at  the  posterior  edge. 
A broken  plate  (Text-fig.  1 2 d)  located  on  the  slab  BMNH27388,  measures  8 x 7 mm,  and  is  perforated 


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PALAEONTOLOGY,  VOLUME  34 


medially  by  a 2 mm  wide  foramen.  Although  Dineley  and  Loeffler  (1976)  have  described  distinctive  pineal 
foramina  in  several  Canadian  traquairaspidiforms,  the  large  size  of  the  opening  shows  that  this  specimen 
probably  represents  an  orbital  plate. 

The  branchial  opening  is  about  4 mm  long  x 3 mm  wide,  postero-laterally  facing,  and  located  at  about  two- 
fifths  along  the  length,  from  the  front  of  the  branchio-cornual  plate  (Text-fig.  1 2 e).  Fine  elongated  tubercles 
run  longitudinally  behind,  and  curve  across  the  plate  in  front  of,  the  branchial  opening. 

Although  the  two  types  of  ventral  disc  could  prove  to  indicate  two  distinct  species,  they  have  identical  lateral 
ornamentation  and  proportional  overlap  (Table  3;  Text-fig.  12a,b).  Also,  problems  occur  with  categorizing  the 
other  plates  into  two  types.  This  may  indicate  that  the  two  types  of  ventral  discs  are  dimorphic,  possibly  sexual, 
examples  of  the  same  species.  White  (1946)  showed  the  segmented  longitudinal  sensory  canals  running  in 
association  with  the  longitudinal  row  of  tubercles  on  each  lateral  side  of  ventral  disc  type  1.  Pores  show  the 


te  (T-fig.  12.  Traquairaspis  campbelli  (Traquair).  a,  ventral  disc  type  1,  a-a,  b-b,  lines  of  cross  section, 
BI/1NH37379,  b,  ventral  disc  type  2,  a-a,  b-b,  lines  of  cross  section,  BMNH27037.  c,  ditto,  detail  of 
ornamentation  on  central  area.  D,  fragmentary  orbital  plate,  p.27388.  E,  branchio-cornual  plate,  plus  cross 
section,  BMNH43544.  f,  detail  of  dorsal  disc  ornamentation,  BMNH43523.  G,  flank  scale,  on  BMNH43525. 
h,  ridge  scale,  on  BMNH43525.  Abbreviation:  sea,  smooth  central  area. 

presence  of  post-oral  canals  running  on  to  the  anterior  half  of  the  smooth  central  area.  These  also  show  the 
positions  of  probable  ventral  medial  sensory  commissures. 

On  the  slab  BMNH43525,  there  are  scales  of  two  types.  The  ridge  scales  (Text-fig.  1 2 h)  lack  the  pronounced 
spine  or  spinal  process  of  phialaspidids,  and  instead  they  have  a medially  placed  elongated  tubercle.  The  flank 
scales  (Text-fig.  1 2 g)  are  very  wide  compared  to  those  of  P.  symondsi.  The  most  complete  ridge  scale  measures 
6 mm  long  x 4 mm  wide  and  the  most  complete  flank  scale  measures  5 mm  long  x 10  mm  wide. 

Remarks.  The  morphological  similarity  and  contemporaneity  with  the  Canadian  traquair- 
aspidiforms supports  Dineley  and  Loeffler’s  (1976)  assignment  of  its  part  of  Scotland  to  the  North 
American  Silurian  continent.  This  arrangement  is  shown  by  Scotese  el  al.  (1985)  on  their  Silurian 
and  Devonian  base  maps. 

Genus  rimasventeraspis  nom.  nov. 

Etymology.  Rimas  venter , Latin,  fissured  belly,  and  as  pis.  Greek,  shield. 

Type  species.  ? Traquairaspis  angusta  Denison,  1963. 

Remarks.  The  previous  generic  name  is  pre-occupied  ( Yukonaspis  Kobayshi,  1936). 


TARRANT  LOWER  DEVONIAN  OSTRACODERM 


425 


Diagnosis.  Ventral  disc;  80-85  mm  long  x 35-5  mm  wide,  with  medially  notched  posterior  edge. 
Ventral  smooth  central  area  covers  nearly  all  the  disc,  is  partly  subdivided  into  units  which  grade 
into  tubercles  on  antero-lateral  edges.  Ornament  of  stellated  tubercles  became  elongated  and 
divided  by  fine  ridges  on  lateral  sides. 

Rimasventeraspis  august  a (Denison,  1963) 

1963  ITraquairaspis  angusta  Denison,  pp.  132-135,  figs  78  and  79. 

1964  Yukonaspis  angusta  (Denison);  Obruchev,  p.  63;  Stensio,  p.  364,  fig.  123a. 

Holotype.  PU 17388,  ventral  disc. 

Type  horizon  and  locality.  Silurian,  Ludlow/Pridoli,  Beaver  River,  South-eastern  Yukon,  Canada. 
Diagnosis.  As  for  genus,  the  only  known  species. 

Remarks.  A ventral  disc  fragment  described  by  Dineley  and  Loetfler  (1976)  as  ‘Traquairaspididae 
indet.  Type  1 ’,  from  the  Pridoli  of  the  Delorme  Formation,  Mackenzie,  Canada,  may  be  conspecific 
with,  or  closely  related  to,  R.  angusta. 

Discussion.  The  Traquairaspidinae  are  readily  distinguished  from  the  Phialaspidinae,  by  a ventral 
disc  with  steep  sides  and  a large  ventral  central  region  extending  to  the  posterior  edge.  The 
ornamentation  of  small  cyclomoriform  units  suggests  a more  scale-like  dermal  arrangement  than  is 
found  on  the  phialaspidinids.  This,  together  with  the  wide  flank  scales  and  the  absence  of  a specific 
pattern  of  adult  growth,  would  suggest  a more  primitive  condition,  in  comparison  with 
undifferentiated  very  scale-like  ornamentation  and  extremely  wide,  spindly  scales  of  the  Ordovician 
heterostracon  Arandaspis  (Ritchie  and  Gilbert-Tomlinson  1977). 

RESTORATION  OF  PHIALASPIDID  CARAPACES 

The  reconstructions  of  phialaspidid  carapaces  (Text-figs  13  and  14)  are  based  upon  average 
measurements  (Tables  1 and  2)  because  of  the  large  proportional  range  of  individual  plates,  in 
particular  in  P.  symondsi.  They  have  been  based  upon  specimens  showing  plate  fusion,  the  matching 
of  similarly  shaped  and  sized  edges,  the  similarity  of  alignment  and  type  of  ornament,  the  matching 
of  the  sensory  canal  system  and  plate  orientation  in  other  heterostracans.  Impressions  were  taken 
of  individual  specimens  of  each  component  plate,  and  models  were  made  for  both  P.  symondsi  and 
T.  pococki.  This  has  shown  that  the  plate  arrangements  in  both  genera  were  identical,  with  the 
exception  of  the  junction  of  orbital  plates  of  P.  symondsi  between  the  rostrum  and  the  pineal  plate. 
In  certain  regions  one  edge  is  often  more  strongly  angled  than  its  corresponding  plate  margin, 
suggesting  (White  1946)  the  former  presence  of  small  areas  of  connective  tissue. 

INTERNAL  ANATOMY 

Impressions  of  internal  organs  on  the  inside  of  the  plates  tend  to  be  obscured  by  impressions  of  plate 
growth.  Partly  because  of  this,  with  the  exception  of  the  pineal  organ,  there  are  no  distinguishable 
impressions  of  the  brain,  the  semicircular  canals,  or  nasal  sacs. 

Impressions  of  the  vascular  system.  The  impressions  of  vessels  and  possibly  nerve  fibres,  in  the  basal 
laminated  layer  of  the  exoskeleton,  can  be  seen  on  many  of  the  specimens  of  P.  symondsi  from 
Devil's  Hole.  These  are  clearest  where  radiating  from  the  centres  on  the  interiors  of  the  ventral  discs 
(Text-fig.  10c).  The  impressions  are  too  incomplete  to  observe  their  general  ramification,  but,  at 
frequent  intervals  along  their  lengths,  branches  leave  at  right-angles  to  run  through  the  basal 
laminated  layer  into  the  exoskeleton.  As  Janvier  and  Blieck  ( 1979)  have  observed,  these  are  usually 
seen  as  small  foramina  in  the  basal  laminated  layer  in  heterostracans. 


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PALAEONTOLOGY,  VOLUME  34 


bro 


mdc 


20m  m 


IP 


/*/ I.W'I *J  I ft/:‘ ■'.->)  V 


• poc 


.vie 


MPi  / ; / 

|»p^  / / 

vv  ^ ✓*  m“T 


text-fig.  13.  Phialaspis  symondsi  (Lankester),  reconstruction  ot  headshield.  a,b,  dorsal  view  showing 
ornamentation  and  sensory  canal  system.  c,d,  ventral  view  showing  ornamentation  and  sensory  canal  system. 
Abbreviations:  alp,  anterior  lateral  plate;  bep,  branchio-cornual  plate;  bro,  branchial  opening,  cor,  circum- 
orbital  sensory  canal;  dd,  dorsal  disc;  dv,  dorsal  vane;  ior,  inter-orbital  sensory  canal;  ldc,  lateral  dorsal 
longitudinal  sensory  canal;  lp,  lateral  plate;  ltc,  lateral  transverse  sensory  commissure;  mdc,  medial  dorsal 
longitudinal  sensory  canal;  mop,  median  oral  plate;  mtc,  medial  transverse  sensory  commissure,  or,  oibit,  orp, 
orbital  plate;  pi.  pineal  opening;  pip,  pineal  plate;  poc,  post-oral  sensory  canal;  ro,  rostrum,  sea,  smooth 
central  area;  sor,  supra-orbital  sensory  canal;  vd,  ventral  disc;  vie,  ventral  longitudinal  sensory  canal. 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


427 


B 


text-fig.  14.  Reconstruction  of  headshields.  a,b,  Phialaspis  symondsi  (Lankester);  a,  lateral  view;  b,  lateral 
view  of  anterior  portion  with  sensory  canal  system.  c-G,  Toombsaspis  pococki  (White);  c,d,  dorsal  view 
showing  ornamentation  and  sensory  canal  system;  e,f,  ventral  view  showing  ornamentation  and  sensory  canal 
system;  G,  lateral  view.  (See  Text-fig.  13  for  symbols) 

A cone-shaped  structure  (Text-fig.  1 5 F)  found  only  on  the  branchio-cornual  plate, 
SHRCM.G081 52/1,  runs  into  the  exoskeleton  of  the  lateral  keel,  from  near  the  branchial  opening 
on  the  branchial  duct.  It  is  6 mm  long,  4 mm  wide  at  its  base,  tapers  to  I mm  wide  at  its  tip,  and 
lies  at  an  antero-lateral  angle  of  50°  from  the  branchial  duct.  Impressions  of  vessels  adjoin  it  in 
places,  in  particular  at  the  tip. 

Branchial  structures.  The  internal,  paired  and  ovate  impressions,  running  in  longitudinal  rows  along 
heterostracan  dorsal  and  ventral  shields,  are  generally  considered  to  have  been  made  by  gill 
pouches,  as  originally  suggested  by  Woodward  (1891).  Stensio  (1958)  interpreted  longitudinal 
grooves  on  the  ovate  impressions  as  gill  lamellae.  Tarlo  and  Whiting  (1965)  considered  that  the 
paired  impressions  were  made  by  head  somites,  which  were  used  to  pump  the  gills.  In  contrast, 
Janvier  and  Blieck  (1979)  considered  that  the  cephalic  somatic  musculature  was  much  reduced  or 
absent  in  the  Heterostraci,  and  its  place  filled  by  the  branchial  apparatus,  and  that  the  impressions 
they  observed  represented  branchial  and  extrabranchial  divisions  of  the  gill  pouches,  visceral  arches 
with  attachment  points  to  the  exoskeleton,  and  an  arrangement  of  nerves  closely  resembling  those 
found  on  the  branchial  regions  of  the  Osteostraci,  and  the  ammocete  larva. 

White  (1946)  recognised  paired  branchial  impressions  on  the  anterior  parts  of  a ventral  disc  of 
T.  camphelli.  Although  he  was  uncertain  about  the  ‘lobes’  originally  found  by  Wills  (1935),  on  the 
smooth,  ventral  central  area  of  P.  symondsi , he  observed  a pattern  of  rounded  ridges  on  the  external 
surface  of  that  region,  in  the  type  specimen  of  ‘ Psammosteus  anglicus ’.  The  ventral  discs  from 
Devil’s  Hole  show  that  these  impressions  run  around  the  shapes  of  three  usually  strong  and 
commonly  found  internal  impressions  (Text-fig.  15a-c).  The  most  anterior  of  these  is  medially 


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PALAEONTOLOGY,  VOLUME  34 


text-fig.  15.  Internal  impressions,  a-g,  Phialaspis  symondsi  (Lankester);  a,  anterior  part  of  ventral  disc 
showing  branchial  impressions,  SHRCM.G3339;  b,  immature  ventral  disc  showing  branchial  impressions, 
SHRCM.G3527A;  c,  internal  impression  of  anterior  part  of  ventral  smooth  central  region,  SHRCM.G08144; 
d,  imperfect  dorsal  disc  showing  branchial  impressions,  SHRCM.G08144 ; E,  internal  view  of  lateral  plate, 
SHRCM.G08173/2;  f,  internal  view  of  branchio-cornual  plate  showing  impressions  on  branchial  duct,  with 
detail  of  vascular  structure,  SHRCM.G08152/I  g,  internal  view  of  orbital  plate,  SHRCM.G3387.  h, 
Toombsaspis  pococki  (White),  anterior  of  ventral  disc  showing  internal  impressions,  BU2099.  Abbreviations: 
as,  anterior  side;  asca,  anterior  edge  of  smooth  central  region;  bmb,  branchial  muscle  block;  brd,  branchial 
duct;  bro,  branchial  opening;  bv,  blood  vessel;  ci,  central  impression;  gr,  growth  ridge;  hbm,  hypobranchial 
muscles;  lsg,  groove  for  longitudinal  sensory  canal;  msc,  muscle  scars;  or,  orbital  opening;  pea,  pre-branchial 
central  impression;  plb.  posterior  limit  of  branchial  region;  pop,  post-oral  process;  pva,  points  of  vascular 
attachment;  sea,  smooth  central  area;  tvm,  transverse  muscles;  va,  visceral  arch. 


EXPLANATION  OF  PLATE  6 

Figs  1-5.  Phialaspis  symondsi  (Lankester),  lower  Devonian,  Welsh  Borderland.  1,  SHRCM.G3339/1,  anterior 
of  internal  mould  of  ventral  disc,  x2.  2,  SHRCM.G08152/1,  internal  impression,  detail  of  branchial  duct, 
x4.  3-5,  regions  of  injury  on  ventral  discs;  3,  SHRCM.G08168,  external  right  anterior  side  of  cast,  x 1 -5 ; 
4,  SHRCM.G08 195/1,  anterior  of  internal  mould,  x L5;  5,  SHRCM.G3302/1 . internal  anterior  of  cast,  x 1. 


PLATE  6 


TARRANT,  Phicilcispis  symondsi 


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PALAEONTOLOGY,  VOLUME  34 


placed  and  rounded,  with  an  average  diameter  of  10  mm.  At  its  posterior  end,  the  other  impressions 
form  a pair,  join  medially  and  fan  out  antero-laterally  on  each  side,  to  define  the  antero-lateral  edges 
of  the  smooth  central  region.  The  average  measurements  of  each  of  these  impressions  are  about 
14  mm  long  x 7 mm  wide. 

Branchial  impressions  can  be  best  seen  on  the  internal  mould  of  the  ventral  disc,  SHRCM.G3339 
(PI.  6,  fig.  1 ; Text-fig.  15a)  and  these  run  from  the  three  centrally  placed  impressions  to  the  antero- 
lateral edges  of  the  disc.  Their  posterior  edges  are  clearly  defined,  and  Wills  (1935)  described  these 
in  his  specimens,  as  grooves  of  indeterminate  origin.  Lines  of  beaded,  2 mm  wide  and  raised 
impressions,  divided  by  lines  of  pits,  are  contained  on  each  side  within  a fan-shaped  area.  Seven  or 
possibly  eight  rows  are  on  the  left  side.  On  an  immature  ventral  disc  SHRCM.G08192  (Text-fig. 
15b)  the  beaded  impressions  are  found  closer  beneath  the  internally  flattened,  antero-lateral  corners 
of  the  smooth  central  area,  and  the  two  sides  are  closer  together.  This  resembles  the  arrangement 
on  the  ventral  disc  of  T.  pococki  (Text-fig.  1 5 h).  In  the  dorsal  discs,  only  the  distorted  specimen 
SHRCM.G08194  (Text-fig.  1 5 D).  shows  any  branchial  impressions,  and  these  are  incomplete,  but 
are  of  the  same  beaded  type  as  those  on  the  ventral  discs. 

A row  of  Y-  or  U-shaped  impressions,  running  along  the  dorsal  side  of  the  heterostracan 
branchial  duct,  and  corresponding  to  the  more  medially  placed  branchial  impressions,  have  been 
interpreted  as  part  of  the  gill  pouches  (Kiaer  1930;  Kiaer  and  Heintz  1935;  Wills  1935),  as 
impressions  marking  the  positions  of  branchial  pouch  openings  (Watson  1954;  Stensio  1958,  1964; 
Tarlo  and  Whiting  1965;  Jarvik  1980),  or  of  visceral  arches  (Halstead  1982). 

The  branchial  duct  in  P.  symondsi  can  be  detected  running  longitudinally,  from  below  the  orbit 
and  the  deepest  part  of  the  lateral  plate,  to  the  branchial  opening  (Text-fig.  15e,g,f).  It  is  seen  most 
clearly  on  the  branchio-cornual  plate  SHRCM.G08152/I  (PI.  6,  fig.  2;  Text-fig.  1 5 f),  where  well- 
defined  impressions  run  transverse  across  it,  along  the  length  of  its  dorsal  side,  and  most  strongly 
near  the  branchial  opening. 

With  the  possible  exception  of  a large  blood  vessel  on  the  branchial  duct  of  the  orbital  plate 
SHRCM.G3387  (Text-fig.  1 5 G),  no  obvious  impressions  of  branchial  blood  vessels  or  nerves  have 
been  detected. 

The  rows  of  beaded  and  depressed  impressions  undoubtedly  represent  the  positions  of  visceral 
arches.  The  incompleteness  and  inconsistency  of  the  impressions  appears  to  indicate  that  the  main 
respiratory  movements  were  endoskeletal,  and  were  mostly  made  by  the  branchial  region  when  it 
was  fully  expanded.  The  flexibility  and  elasticity  of  the  cartilaginous  visceral  arches  would  have  been 
an  important  factor  in  the  extension  and  contraction  of  the  branchial  regions.  This  explains  the  rows 
of  beaded  impressions,  which  would  represent  the  positions  of  branchial  muscle  plates  overlying  the 
visceral  arches,  and  transverse  muscles  running  in  between.  The  large  paired  impressions,  usually 
found  under  the  smooth  ventral  central  area,  have  all  the  appearance  of  two  large  hypobranchial 
muscles,  which  would  have  served  to  raise  and  lower  the  branchial  regions. 

The  impressions  on  the  branchial  duct  of  P.  symondsi  could  hardly  be  described  as  Y-  or  U- 
shaped,  but  rather  as  bands  joining  the  more  medial  branchial  regions,  and  swathing  the  branchial 
duct.  It  is  unlikely  that  impressions  left  by  the  extrabranchial  atria  would  be  found  on  the  lateral 
branchial  region,  since  they  would  have  been  positioned  away  from  the  exoskeleton.  The 
impressions  in  P.  symondsi  appear  more  like  muscle  bands,  which  would  have  strengthened  the 
internally  hollowed  and  bulky  lateral  exoskeleton,  and  could  have  forced  water  out  through  each 
branchial  opening  by  longitudinal  waves  of  compression,  to  aid  in  steering  and  in  controlling  pitch 
and  roll. 

Janvier  and  Lund  (1983)  argued  that  hypobranchial  somatic  musculature,  found  on  the 
myxinoids,  anaspids,  and  to  a lesser  extent  on  the  lampreys,  mobilized  the  anterior  parts  of  the 
body,  compensating  for  the  lack  of  paired  fins.  The  same  was  possible  for  a juvenile  P.  symondsi 
at  a stage  prior  to  plate  growth,  as  was  suggested  for  the  Heterostraci  by  Tarlo  and  Whiting  (1965). 
These  same  muscular  contractions  could  have  been  used  by  the  adults,  to  control  jet-aided  steering 
and  balance. 

It  seems  odd  that  the  Heterostraci  did  not  need  paired  fins;  it  seems  likely  that  they  had  evolved 


TARRANT:  LOWER  DEVONIAN  OSTRACODERM 


431 


their  own  substitute.  P.  symondsi , with  its  streamlined  shape,  large  dorsal  and  lateral  vanes,  which 
indicate  an  active  existence,  and  its  obvious  ability  to  frequent  narrow  meandering  channels,  must 
have  manoeuvred  more  efficiently  than  is  supposed  for  the  Heterostraci,  despite  its  rigid  carapace. 
Water  under  pressure,  forced  out  of  the  branchial  opening  on  one  side,  would  push  the  same  side 
downwards,  causing  the  animal  to  roll.  If  this  coincided  with  a yaw  in  the  same  direction,  the  animal 
would  bank,  using  its  wide  undersurface  to  effect  a turn.  If  water  was  expelled  with  force  from  both 
branchial  openings  at  the  same  time  this  would  raise  the  anterior  end,  which  could  direct  the  animal 
upwards,  and  slow  it  down,  or  stop  its  forward  motion,  using  the  underside  as  a brake.  It  seems 
likely  that  this  proposed  method  of  jet-aided  steering  could  have  originally  developed  as  a method 
of  expelling  debris  from  the  large  and  enclosed  branchial  regions. 

Jarvik  ( 1980)  suggested  that  water  expelled  through  the  branchial  openings  of  the  pteraspidiforms 
would  have  aided  the  forward  movement  of  the  animals  to  some  extent,  as  is  known  for  modern 
actinopterygians.  As  many  heterostracans  are  streamlined,  especially  so  with  certain  large  and 
advanced  pteraspidiforms,  it  must  be  assumed  that  efficient  manoeuvrable  free-swimming  must 
have  been  achieved,  despite  the  inflexibility  of  the  carapace.  As  the  branchial  openings  on  most 
species  are  directed  posteriorly,  it  is  probable  that  forward  movements  were  jet-aided.  The 
independent  expulsion  of  water  to  aid  in  steering  in  these  animals  would  be  less  efficient,  and  would 
have  worked  in  the  opposite  way,  to  the  method  suggested  for  P.  symondsi. 

Oral  and  olfactory  apparatus  and  feeding  methods.  It  has  been  generally  accepted  that  two  circular 
impressions  found  internally  on  the  anterior  edge  of  the  heterostracan  dorsal  headshield  indicate  the 
position  of  nasal  sacs,  as  first  described  by  Jaekel  ( 1903).  Rostral  spaces,  medially  divided  to  various 
degrees,  have  been  found  in  certain  pteraspidiforms  (Stensio  1927,  1932a;  Heintz  1962;  Denison 
1964,  1970)  and  in  the  cyathaspidid  Torpedaspis  (Broad  and  Dineley  1973).  With  the  exception  of 
Stensio  (1958,  1964,  1968),  who  considered  that  the  spaces  were  filled  with  cartilage,  it  has  been 
generally  agreed  that  they  would  have  housed  the  anterior  part  of  the  nasal  sacs.  Although  it  has 
been  considered  that  in  some  heterostracans  the  olfactory  organ  or  organs  opened  into  the  buccal 
cavity  (White  1935),  notches  on  the  anterior  edge  of  the  dorsal  armour  have  been  described  as 
external  nares  (Kiaer  and  Heintz  1932;  Watson  1954;  Novitskaya  1975).  Paired  grooves  on  the 
rostral  under  surface  of  certain  pteraspidiforms  have  been  described  as  olfactory  grooves  (Zych 
1931 ; Tarlo  1961),  or  as  impressions  indicating  the  position  of  tentacles  (Stensio  1958;  Janvier  1974; 
Jarvik  1980). 

Stensio  (1927,  1958,  1964)  was  the  first  to  suggest  a close  affinity  between  the  Myxinoidea  and  the 
Heterostraci.  In  order  to  do  this,  he  considered  that  the  Heterostraci  had  a palatosubnasal  lamina 
with  'upper  labial  plates’  against  which  the  oral  plates  worked,  separating  the  oral  cavity  from  a 
single  medially-placed  olfactory  organ  duct  and  opening.  As  no  fossil  evidence  of  'upper  labial 
plates’  has  been  found,  Denison  (1960),  White  ( 1961 ),  Tarlo  ( 1961 ),  Heintz  (1962),  Halstead  (1973), 
and  Novitskaya  (1975),  disagreed  with  Stensio’s  suggested  parts.  Stensio  was  supported  by  Jarvik 
(1980)  and  by  Janvier  (1974)  who  later  rejected  a close  relationship  between  the  two  classes,  mainly 
because  the  Myxinoidea  have  a single  semicircular  canal  and  that  the  Heterostraci  had  two  (Janvier 
and  Blieck  1979),  although  they  still  maintained  that  the  Heterostraci  had  a 'palatosubnasal 
lamina’,  and  favoured  for  most  Heterostraci,  a medial  position  for  a single  olfactory  opening,  duct 
and  organ.  In  contrast,  Halstead  (1973)  and  Novitskaya  (1975)  considered  that  there  were  two 
olfactory  organs,  as  in  gnathostomes. 

The  small  size  and  the  positions  of  phialaspidid  orbital  openings  suggest  a limited  range  of  vision. 
Therefore,  there  must  have  been  a heavy  reliance  upon  well-developed  olfactory  organs,  and 
possible  tactile  taste  organs,  to  detect  food. 

In  P.  symondsi , the  folded  and  contorted  under-surface  of  the  back  of  the  rostrum  indicates  a 
likely  continuation  of  the  external  skin  that  covered  the  ventral  pre-oral  surface,  and  an  attachment 
area  for  the  soft  dorsal  parts  of  the  mouth.  The  absence  of  rostral  spaces,  the  large  median  oral  plate 
which  would  have  filled  the  oral  cavity  medially,  plus  the  likely  soft  supportive  and  muscular 
structures  of  the  oral  region,  suggest  the  anterior  absence  of  a palatosubnasal  lamina,  and  a more 


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text-fig.  16.  Phialaspis  symondsi  (Lankester).  a,  ventral  view  of  oral  region,  b,  anterior  part  of  head  with 
mouth  closed,  c,  ditto,  with  mouth  open.  Abbreviations:  alp,  anterior  lateral  plate;  ba,  barbels;  lp,  lateral 
plate;  mop,  median  oral  plate;  na,  narial  opening;  ns,  nasal  sac;  pos,  pre-oral  surface. 

posteriorly  placed  olfactory  complex,  than  is  accepted  on  the  pteraspidiforms.  This  indicates  lateral 
positions  for  possible  inhalant  openings.  It  seems  that  the  raised  notch  on  the  anterior  lateral  plate 
represents  an  inhalant  opening,  indicating  that  P.  symondsi  had  paired  inhalant  olfactory  ducts,  the 
foramina  surrounding  the  raised  notch  might  suggest  the  positions  of  tactile  and  possible  taste 
organs.  These  could  possibly  be  extensions  of  the  olfactory  apparatus,  as  in  the  myxinoids  (Janvier 
1974). 

The  raised  notch  and  foramina  may  have  served  to  house  a large  tentacle  on  each  side  of  the  oral 
cavity.  The  abrasions  on  the  sides  of  the  median  oral  plate  appear  to  have  been  caused  by  friction 
against  the  overlapping  anterior  lateral  plates,  indicating  that  the  latter  were  hinged  at  their 
posterior  edges,  and  would  have  swung  open  as  the  median  oral  plate  was  extruded.  This  action, 
taking  into  account  the  shape  of  the  front  of  the  lateral  plates,  could  have  been  restrained  by  such 
tactile  organs. 

It  seems  likely  that  the  nasal  sacs  would  have  been  separated,  and  have  rested  under  the  anterior 
of  the  orbital  plates.  A more  medial  position  for  a single  olfactory  organ  would  have  meant  that 
it  had  to  rest  under  the  telencephalon,  which  would  have  involved  excessive  cranial  flexure  and 
where  there  would  have  been  insufficient  room. 

Georgieva  et  al.  (1979)  considered  the  ‘sensory  buds’  on  the  barbels  of  Myxine  glutinosa 
resembled  the  taste  buds  of  the  gnathostomes,  and  Baatrup  (1983)  described  sensory  buds  in  larval 
lampreys  akin  to  the  taste  buds  of  other  vertebrates.  Therefore,  it  is  feasible  that  P.  symondsi  may 
have  possessed  similar  structures,  in  particular  on  its  tactile  organs. 

Various  suggestions  have  been  made  about  the  oral  workings  of  Heterostraci,  particularly  the 
pteraspidiforms  and  certain  cyathaspidiforms.  Kiaer  (1928)  considered  that  the  oral  plates  bit 
against  the  maxillary  brim,  on  the  ventral  margin  of  the  rostral  region.  Stensio  (1932)  and  Janvier 
(1974)  thought  that  they  worked  in  a myxinoid-like  manner.  White  (1935)  considered  that  the  oral 
plates  were  connected  together  by  the  epidermis,  and  would  have  moved  down  and  forwards,  to 
form  a scoop  or  shovel,  and  Denison  (1961)  further  suggested  that  the  protrusible  mouth  could  have 
selected  and  picked  up  food,  including  small  invertebrates.  This  could  have  been  aided  by  inhalant 
respiratory  currents.  Dineley  and  Loeffler  (1976)  described  a large  plate  in  the  oral  region  of 
Poraspis  cf.  polaris , which  they  interpreted  as  a large  single  oral  plate  used  as  a scoop. 

P.  symondsi  had  far  fewer  oral  components  than  the  pteraspidiforms,  and  it  is  inconceivable  to 
imagine  its  large  median  oral  plate  retracting,  Myxine -fashion,  into  its  gullet.  The  shape  of  the 
median  oral  plate  indicates  that  it  would  have  worked  in  the  way  that  White  (1935)  and  Denison 
(1961)  described  for  the  pteraspidiforms.  The  elongate  and  convex  area  on  its  inner  side  indicates 
an  attachment  area  for  protractor  and  retractor  muscles,  and  this  suggests  that  the  median  oral 
plate  could  have,  if  needed,  worked  rapidly,  snapping  shut  with  force.  The  smooth  edges  show  that 


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433 


it  had  no  grasping  or  cutting  facilities,  although  it  may  have  worked  against  the  maxillary  flange 
and  pre-oral  surface.  The  size  of  the  oral  cavity,  surrounded  by  rigid  lateral  plates,  limited  the  size 
of  food  engulfed.  Nevertheless,  the  oral  region  of  P.  symondsi  has  all  the  appearance  of  working  like 
an  efficient  trap,  with  its  scooping  median  oral  plate  embraced  by  anterior  lateral  plates. 

The  shape  of  P.  symondsi , albeit  constricted  by  an  inflexible  carapace,  has  the  lines  of  an  active 
feeder,  rather  than  a sluggish  animal  swallowing  mud  and  filtering  organic  substances,  as  has  often 
been  supposed  for  the  Heterostraci  (Halstead  1985).  The  apparent  lack  of  wear  on  the  tip  of  the 
median  oral  plate  appears  to  substantiate  this.  The  small  size  and  structure  of  the  oral  region  would 
have  prevented  total  filter  feeding  in  open  water.  As  White  (1946)  suggested  for  Phialaspis , the 
smooth  ventral  central  area  could  have  been  used  as  a sliding  plane  and  fulcrum,  while  the  animal 
wriggled  across  the  surface  of  the  substrate.  Taking  the  dorso-ventrally  flattened,  and  anteriorly 
heavy,  carapace  into  consideration,  plus  occasional  abrasion  observed  on  the  anterior  part  of  the 
ventral  discs  and  undersurface  of  the  branchio-cornual  plates,  the  crenulated  tip  of  the  rostrum,  and 
the  ventral  position  of  the  oral  region,  it  seems  likely  that  P.  symondsi  was  mainly  a benthic  feeder, 
rooting  in  the  substrate.  This,  plus  its  common  and  wide  occurrence,  indicates  that  it  was  not  a 
highly  specialized  feeder,  but  more  of  an  opportunist,  feeding  on  a wide  range  of  animal  and 
vegetable  matter,  both  dead  and  alive.  Its  small  mouth  rules  out  any  extensive  predatory  role,  but 
it  appears  well-equipped  to  snap  up  small  animals,  which  it  would  have  disturbed  out  of  the 
substrate.  T.  pococki  had  a more  evenly  vaulted  cephalothorax  and  a short  rostrum.  Its  oral  region 
was  more  terminal  in  position  (Text-fig.  14e-g),  which  indicates  that  it  may  have  fed  not  so  much 
within  the  substrate,  but  more  on  or  possibly  somewhat  above  its  surface. 


GROWTH  AND  ONTOGENY 

Despite  divergent  views  on  heterostracan  exoskeletal  growth,  evidence  is  patchy.  From  studies  on 
elasmobranch  scales,  0rvig  (1951)  developed  the  Lepidomorial  Theory,  which  Stensio  (1958)  used 
to  interpret  heterostracan  exoskeletal  growth.  This,  he  considered,  was  achieved  in  two  ways:  (1) 
cyclomorial  growth,  in  which  peripheral  concentric  growth  took  place  around  an  initial  primordium, 
and  (2)  synchronomorial  growth,  in  which  calcification  was  achieved  simultaneously,  to  produce  a 
completed  part  of  the  carapace.  This  was  mainly  based  on  the  assumption  that,  once  a part  of  the 
carapace  mineralized,  it  remained  unchanged,  and  that  the  mode  of  growth  could  be  deduced  from 
the  form  of  dentine  patterning.  However,  Dineley  and  Loeftler  (1976)  discovered  concentric  growth 
impressions  in  association  with  synchronomorial  dentine  patterns  in  certain  cyathaspidiform 
shields.  From  this,  they  argued  that  the  Lepidomorial  Theory  was  not  applicable  to  heterostracan 
exoskeletal  growth,  and  was  only  useful  to  describe  cyclomoriform  and  synchronomoriform 
ornamental  pattern. 

An  example  of  phylogenetic  heterostracan  exoskeletal  growth  can  now  be  demonstrated,  since 
Elliott  (1984)  has  shown  that  the  pteraspidi forms  were  derived  from  the  cyathaspidiforms.  The 
superficial  layer  formed  prior  to  the  underlying  layers  in  the  cyathaspid  (Denision  1964),  and  during 
early  ontogeny  in  the  pteraspidiforms  (Denison  1973;  White  1973).  The  cyathaspidiform  shield  did 
not  form  until  the  animal  had  achieved  its  definitive  size  (Denison  1964;  Dineley  and  Loeffler  1976), 
whereas  the  pteraspidiform  shield  grew  as  separate  peripheral  plates,  which  fused  together  at 
maturity  (Heintz  1938;  White  1958).  This  latter  process  was  progressively  delayed  in  later  forms 
(White  1958). 

As  Dineley  and  Loeffler  (1976)  argued,  it  is  likely  that  the  earliest  traquairaspidiforms  had  an 
undivided  dorsal  shield,  although  how  this  was  formed  is  open  to  speculation.  Nevertheless,  to  aid 
in  synchronous  growth  between  the  animal  and  its  exoskeleton,  later  forms  attained  a mode  of  plate 
division  parallel  to  the  pteraspidiforms. 

The  orbital,  pineal  and  lateral  plates  mainly  grew  cyclomorially  by  peripheral  additions.  Much 
the  same  could  be  said  about  the  regions  of  mature  growth  in  the  other  major  plates.  Nevertheless, 
it  would  appear  likely  that  some  plate  remodelling  may  have  been  required  for  fusions  and  to 
sustain  the  proportional  vaulting  and  matching  of  peripheral  plate  contacts.  Similar  speculations 


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have  been  made  about  resorption  and  regrowth  in  the  pteraspidiforms  (Halstead  1969;  Denison 
1973 ; White  1973),  although  it  has  never  been  demonstrated.  However,  Tarlo  (1965)  has  shown  that 
certain  heterostracans  were  capable  of  resorption  and  regrowth  within  their  middle  exoskeletal 
layers,  to  aid  normal  plate  enlargement.  It  would  appear  that  P.  symondsi  was  at  least  capable  of 
using  resorption  and  regrowth  to  repair  broken  exoskeletal  components  (PI.  6,  fig.  5;  Text-fig.  10). 

Secondary  formation  of  tubercles  overlying  and  replacing  primary  tubercles  has  been  described 
in  various  heterostracans.  These  formed  to  repair  worn  or  damaged  regions  (Tarlo  and  Tarlo  1965; 
Tarlo  1965,  1966;  Denison  1973),  were  preceded  by  resorption  rather  than  wear  (Gross  1961),  or 
represented  a normal  process  of  growth  (0rvig  1976).  In  P.  symondsi  the  large  tubercles  overlying 
smaller  tubercles  on  the  lateral  edges  of  the  branchio-cornual  plates  and  front  part  of  the  rostrum 
are  located  on  likely  regions  of  abrasion. 

Secondary  tubercles  forming  to  fill  spaces  between  primary  tubercles  as  a normal  part  of  plate 
growth  have  not  been  described  in  the  heterostracans.  Despite  this,  the  evidence  of  erupting  and 
developing  tubercles  over  the  surface  of  an  immature  dorsal  disc  and  branchio-cornual  plate  (Text- 
figs  2d  and  6f)  appears  to  show  a ready  ability  to  develop  tubercles  within  the  main  body  of  the 
plates,  as  part  of  the  general  growth.  It  would  seem  to  follow  that  this  mode  of  growth  of  the 
superficial  layer  could  have  been  accompanied  by  resorption  and  regrowth  of  the  underlying 
exoskeletal  layers. 

Tarlo  (1962)  considered  that  the  traquairaspidiform  units  grew  as  isolated  tesserae  which 
ultimately  fused  with  the  main  plates.  Although  no  recognisable  isolated  tesserae  have  been  found 
in  the  beds  containing  P.  symondsi , it  is  conceivable  that  the  units  initially  developed  in  Tarlo’s 
suggested  fashion,  as  is  apparent  from  the  posterior  units  on  the  ventral  disc.  In  certain  instances, 
they  may  not  have  fused  with  the  main  plates  until  their  growth  had  ceased.  However,  evidence  of 
non-cyclomorially  arranged  developing  tubercles  in  an  immature  dorsal  disc  (see  Text-fig.  2d)  and 
the  small  posterior  unit  in  an  immature  branchio-cornual  plate  (Text-fig.  6 j ),  suggests  that  each  unit 
was  also  capable  of  growth  whilst  attached  to  its  neighbouring  units  and  the  main  plate,  thus 
providing  a more  or  less  unified  mode  of  outward  plate  growth.  This  contained  method  of  growth 
could  have  caused  the  basal  laminated  layer  to  fold  inwards  at  the  regions  of  contact  between  each 
unit  and  their  contact  with  the  main  plate,  thus  leaving  the  internal  ‘constriction’  impressions  often 
observed  at  the  edges  of  the  units  (PI.  1,  fig.  2;  PI.  3,  fig.  4;  Text-figs  2b  and  6b).  This  mode  of  growth 
enabled  the  ontogenetic  and  phylogenetic  development  of  the  folded  units  forming  the  dorsal  vane. 
This  would  suggest  that  the  depressed  region  in  the  small  dorsal  vane  (PI.  1,  fig.  3;  Text-fig.  3d) 
may  have  contained  recessed  epithelial  tissue,  in  which  new  tubercles  would  have  formed. 

As  is  evident  from  the  most  immature  branchio-cornual  plates  (PI.  3,  figs  1 and  2;  Text-fig.  6f-h), 
the  longitudinal  units  were  either  isolated  or  not  formed  during  early  ontogeny. 

All  the  known  earlier  traquairaspidiform  rostral  plates  (Dineley  and  Loeffler  1976)  could  be 
described  as  an  antero-dorsal  unit,  formed  mainly  by  cyclomorial  peripheral  growth,  with  enlarged 
tubercles  at  the  anterior  apex,  where  it  folds  to  cover  the  dorsal  margin  of  the  oral  cavity.  However, 
in  P.  symondsi , there  would  appear  to  have  been  a new  centre  of  cancellous  and  superficial  layer 
growth  within  the  main  body  of  the  plate,  forming  the  ‘pre-oral  field’. 

As  Tarlo  (1962)  suggested,  it  would  appear  that  the  ventral,  smooth  central  region  achieved  full 
size  and  developed  an  enclosing  band  of  ornamented  growth  prior  to  its  fusion  with,  or  formation 
of,  the  ventral  longitudinal  units  (PI.  4,  fig.  3;  Text-fig.  8c).  The  development  of  the  ventral  smooth 
central  region  is  not  seen  in  any  specimens,  and  its  formation  is  open  to  speculation.  The  ventral 
central  ornamentation  on  certain  Canadian  Pridolian  traquairaspidiforms  (Dineley  and  Loeffler 
1976)  may  illustrate  the  mode  of  origin.  This  grades  from  the  unspecialized  ventral  tubercles  in 
certain  forms,  to  flattened  and  broad  ventral  ornamentation,  which  approaches  the  subdivided 
condition  in  the  ventral  smooth  central  region  of  Rimasventeraspis.  The  abraded  regions  in  P. 
symondsi  show  (Text-figs  6d  and  8 e)  broad  flattened  tubercles  like  the  ventral  pattern  in  the 
Canadian  traquairaspidiforms.  Persistent  abrasion  on  the  ventral  surface  of  active  benthic  animals 
might  have  triggered  selection  for  a permanently  smooth  ventral  central  region.  This  would  have 
greatly  aided  movement  over  the  substrate,  and  might  have  evolved  independently  in  different 


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435 


lineages.  The  anomalous  and  non-abraded  ornamentation  of  the  T.  campbelli  Type  2 ventral  disc 
may  suggest  a different  lifestyle,  and  that  the  tubercle  formation  was  still  inherent,  despite  the 
possible  ancestral  formation  of  a smooth  ventral  central  region. 

The  large  size  range  of  the  phialaspidid  adult  plates  is  mainly  due  to  the  amount  of  outer 
peripheral  growth.  In  the  dorsal  and  ventral  discs,  growth  ridges  become  more  numerous  as  the 
region  extends.  This  shows  that  the  animals  were  capable  of  growth  throughout  life.  The  growth 
ridges  influenced  all  exoskeletal  levels  and  are  seen  most  clearly  as  folds  in  the  nasal  laminated  layer. 
By  folding,  the  exoskeleton  would  have  been  able  to  have  kept  itself  moulded  to  the  animal,  and 
it  appears  that  the  exoskeleton  continued  to  grow  for  a time.  The  resulting  excess  of  exoskeletal 
growth  forced  the  growing  edges  of  a plate  downwards,  then  upwards  at  the  resumption  of 
underlying  growth,  to  form  a growth  ridge.  These  corrugations  not  only  mark  the  rhythmic  growth 
cycles,  but  would  also  have  strengthened  the  plates. 

The  range  in  proportions  of  the  dorsal  vanes,  lateral  keels,  branchial  openings,  smooth  ventral 
regions,  and  the  number  and  size  of  units,  appears  to  have  had  nothing  to  do  with  adult  plate 
growth.  No  consistent  variation  can  be  observed  in  these  parts,  and  it  seems  unlikely  that  they 
represent  species  or  sexual  differences. 

From  the  most  immature  specimens,  it  is  possible  to  estimate  that  P.  symondsi  developed  its 
dermal  plates  when  it  was  about  one-third  the  length  of  the  mature  animal.  This  shows  that  an 
amocoete-like  lifestyle  was  impractical,  since  a borrowing  worm-shaped  body,  unimpeded  by 
immobilizing  plates  of  a carapace,  would  have  been  needed.  Regardless  of  the  great  size  range  of 
orbital  and  pineal  plates,  the  orbital  and  pineal  openings  show  a small  range  in  size.  This  suggests 
that  the  orbits  and  the  pineal  organ  had  probably  reached  full  size  at  the  onset  of  dermal  plate 
development.  Also,  the  posteriorly  directed  branchial  ducts  on  the  juvenile  branchio-cornual  plates 
suggest  that  a relatively  large  area  of  the  thorax  was  free  of  the  headshield.  At  this  stage  of 
development,  the  small  animal  would  have  needed  sufficient  mobility  and  field  of  vision  to  detect 
and  evade  predators.  It  is  possible  that  it  first  fed  upon  planktonic  organisms  in  the  relative  safety 
of  shallow  water,  and  moved  into  deeper  water  to  consume  larger  food  as  it  developed  its  armour 
and  increased  in  size. 


CONCLUSIONS 

The  morphology  of  Phialaspis  symondsi  and  Toombsaspis  pococki  is  sufficiently  different  from  that 
of  Traquairaspis  campbelli , to  necessitate  the  selection  of  two  families,  the  Phialaspididae  and  the 
Traquairaspididae,  within  the  order  Traquairaspidiformes. 

Internal  impressions  on  the  phialaspidid  plates  are  interpreted  as  branchial  musculature  swathing 
the  branchial  duct  in  association  with  the  visceral  arches,  which  could  have  been  used  to  facilitate 
jet-aided  manoeuvrability  to  compensate  for  the  lack  of  paired  fins.  A conspicuous  notch 
surrounded  by  foramina  in  an  anterior  lateral  plate  of  P.  symondsi  suggests  the  occurrence  of  paired 
olfactory  ducts  in  association  with  clusters  of  tactile  and  taste  sensory  organs. 

Dorsal  and  lateral  swimming  stabilizers  and  a smooth  central  ventral  sliding  plane  in  the  Anglo- 
Welsh  phialaspidids,  suggests  an  active  and  mainly  benthic  lifestyle.  These,  their  common 
occurrence,  and  the  workings  of  the  oral  region  in  P.  symondsi , would  imply  that  these  species  were 
probably  opportunist  feeders,  well  able  to  catch  and  consume  small  benthic  animals. 


Acknowledgements.  My  thanks  go  to  Dr  C.  J.  Cleal,  Ms  M.  A.  Rowlands  and  Mr  A.  M.  Tarrant  for  valuable 
help  in  the  field  and  to  the  GCR  unit  of  the  Nature  Conservancy  for  its  excavation  of  the  Devil’s  Hole  stream 
section.  For  hospitality  in  their  various  museum  departments,  I thank  Dr  P.  Forey  and  Ms  S.  Young,  British 
Museum  (Natural  History);  Dr  D.  White,  The  British  Geological  Survey;  Mr  P.  Osborne,  University  of 
Birmingham  Geology  Museum;  and,  in  particular,  Mr  J.  Norton,  Ludlow  Museum.  I wish  to  acknowledge 
useful  correspondence  with  Dr  M.  M.  Smith,  Unit  of  Anatomy  in  relation  to  Dentistry,  Guy’s  Hospital, 
London  and  Dr  J.  D.  D.  Smith,  International  Commission  on  Zoological  Nomenclature.  Helpful  advice  and 
criticism  were  provided  by  Dr  A.  Blieck,  Professor  D.  L.  Dineley,  Dr  L.  B.  Halstead,  Dr  P.  Janvier,  and  Dr 
E.  J.  Loeffier.  The  photographic  illustrations  are  the  work  of  Messrs  T.  Foxall  and  I.  Miller. 


436 


PALAEONTOLOGY,  VOLUME  34 


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PETER  REX  TARRANT 
8 St  Gregory’s  Close 

Typescript  received  5 January  1990  Morville,  Nr  Bridgnorth 

Revised  typescript  received  20  March  1990  Shropshire  WV16  4RL,  UK 


THE  RHYNCHONELLIDE  BRACHIOPOD  EOCOELIA 
FROM  THE  UPPER  LLANDOVERY  OF  IRELAND 

AND  SCOTLAND 

by  E.  N.  DOYLE,  A.  N.  HOEY  and  D.  A.  T.  HARPER 


Abstract.  Biometrical  description  oflarge  samples  (N  > 300)  of  the  rhynchonellide  brachiopod  Eocoelia  from 
the  Kilbride  Formation  (upper  Telychian)  in  the  west  of  Ireland  and  the  Lower  Camregan  Grits  (lower 
Telychian)  of  the  Girvan  district,  south-west  Scotland,  suggests  the  refinement  of  the  stratigraphically 
important  Eocoelia  lineage  in  the  upper  Llandovery.  The  Irish  and  Scottish  species  have  previously  both  been 
assigned  to  Eocoelia  curtisi  Ziegler.  However,  the  Girvan  population  is  significantly  different  from  type  and 
topotype  specimens  from  Tortworth  and  from  the  Irish  material.  The  Scottish  form  is  accorded  separate 
subspecific  status,  Eocoelia  curtisi  immatura  subsp.  nov.,  whereas  the  Irish  form  is  included  in  the  nominate 
subspecies.  The  Irish  and  Scottish  subspecies  are  within  the  upper  and  lower  parts  of  the  range  of  E.  curtisi  s.l. 
respectively.  Interpolation  within  the  lineage  confirms  some  of  the  established  morphological  transpecific 
trends  and  may  permit  more  precise  correlation  within  the  upper  Llandovery. 

The  distinctive  rhynchonellide  brachiopod  Eocoelia  Nikiforova,  1961  (in  Nikiforova  and  Andreeva 
1961)  has  been  of  considerable  importance  in  studies  of  Silurian  benthos.  First,  the  genus  is  the 
eponymous  component  of  the  widespread  Eocoelia  Community  which  occupied  nearshore 
environments  during  the  late  Llandovery  (Ziegler  1965),  and  secondly  the  well-documented 
Eocoelia  lineage  has  been  effectively  used  in  biostratigraphical  correlation  within  lower  Silurian 
shelly  facies  (Ziegler  1966).  Detailed  biometrical  analysis  of  Eocoelia  from  the  west  of  Ireland  and 
south-west  Scotland  has  permitted  a significant  refinement  of  the  existing  Llandovery  part  of  the 
Eocoelia  lineage  which  has  some  bearing  on  correlation  at  and  near  the  base  of  the  Telychian.  The 
analysis,  however,  confirms  some  problems  in  the  application  of  conventional  Linnean 
nomenclature  in  such  gradualist  lineages  (e.g.  Sheldon  1987). 

DISTRIBUTION  OF  EOCOELIA  IN  IRELAND  AND  SCOTLAND 

Eocoelia  is  relatively  widespread  throughout  the  lower  Silurian  of  the  Anglo-Welsh  area  but  its 
distribution  is  comparatively  more  localized  across  Ireland  and  Scotland.  The  occurrences  in  the 
west  of  Ireland  and  Girvan  are  the  only  records  of  the  genus  from  the  Midland  Valley  of  Scotland 
and  its  Irish  equivalent  (Text-fig.  1).  Two  species  of  Eocoelia  have  been  recorded  from  the  West  of 
Ireland.  E.  curtisi  Ziegler  dominates  shell  beds  within  the  lower  part  of  the  Kilbride  Formation 
along  the  Silurian  outcrop  of  North  Connemara  and  on  the  Kilbride  Peninsula  (Piper  1972);  E. 
angelini  occurs  in  the  lower  Wenlock  Lough  Muck  Formation  (E.  sulcata  in  Laird  and  McKerrow 
1970).  Large  new  collections  of  E.  curtisi  have  been  made  from  three  localities  within  the  lower  part 
of  the  Kilbride  Formation  along  the  Llandovery  outcrop  in  north  Connemara  as  follows:  11,  Lough 
Fee  (IGR  L 609790);  12,  Lettershanbally  (IGR  L 584836);  13,  Lee  (IGR  L 570  885)  (see  also  Doyle 
1989).  In  the  Girvan  district,  SW  Scotland,  Eocoelia  has  long  been  known  from  the  Lower 
Camregan  Grits  of  the  Main  Silurian  Outcrop,  south  of  the  Girvan  Valley,  in  Penwhapple  Burn  and 
adjacent  areas  (Davidson  1867).  A.N.H.  has  made  substantial  new  collections  from  three  localities 
within  the  Lower  Camregan  Grits  in  the  Penwhapple  Burn  area  as  follows:  SI,  (NGR  NX  2271 
9807);  S2,  (NGR  NX  2230  9799);  and  S3,  (NGR  NX  2254  9805);  and  a new  occurrence  of  the 
genus  is  recorded  from  the  Craighead  inlier  where  it  occurs  with  Pentameroides. 


| Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  439^454.| 


© The  Palaeontological  Association 


440 


PALAEONTOLOGY.  VOLUME  34 


text-fig.  1.  Location  of  upper  Llandovery  Eocoelia  in  the  Midland  Valley  of  Scotland  and  its  Irish  equivalent. 
Abbreviations:  ci,  Clare  Island;  cp,  Croagh  Patrick;  ng.  North  Galway;  ch,  Charlestown;  1,  Lisbellaw;  p, 
Pomeroy;  c,  Craighead  inlier;  g,  Main  Outcrop,  Girvan;  le,  Lesmahagow;  h,  Hagshaw  Hills;  pt,  Pentland 
Hills;  g.g.f..  Great  Glen  fault;  h.b.f..  Highland  Boundary  fault;  s.u.f.,  Southern  Upland  fault;  i.s.,  putative 
track  of  Iapetus  suture;  M.V.,  Midland  Valley.  Occurrence  of  Eocoelia  indicated  by  asterisk. 


MORPHOLOGICAL  ANALYSIS 

Large  samples  of  Eocoelia  from  Girvan  (N  = 342)  and  Connemara  (N  = 419)  together  with  a more 
limited  sample  of  topotype  material  of  E.  curtisi  from  the  Tortworth  inlier  were  analysed  with 
reference  to  a set  of  continuous  variates  defined  below  and  illustrated  on  Text-figure  3a-c.  The 
ribbing  patterns  of  all  three  samples  were  investigated  with  the  aid  of  frequency  histograms  and 
non-parametric  inferential  statistics.  All  graphical  and  statistical  analyses  were  processed  by  the 
PALSTAT  package  (Harper  and  Ryan  1987)  implemented  on  a BBC  B microcomputer. 

Measurements  taken  (in  mm)  were  si,  sagittal  length;  mw,  maximum  width;  pm,  position  of 
maximum  width  measured  from  posterior  margin;  pt,  position  of  maximum  depth  measured  from 
posterior  margin;  pd,  position  of  deflection  measured  along  sagittal  length;  nr,  total  number  of  ribs; 
lc,  total  length  of  crural  fossettes;  me,  maximum  separation  of  crural  fossettes;  sc,  sagittal  length 
of  crural  fossettes;  mt,  maximum  separation  of  teeth;  mb.  maximum  separation  of  distal  ends  of 
the  brachiophores;  bl,  maximum  length  of  brachiophores ; In,  length  of  notothyrial  platform. 
Matrices  of  sample  sizes  are  shown  in  Table  1. 

Pooled  samples  both  of  the  brachial  and  pedicle  valve  exteriors  and  interiors  from  Connemara, 
Girvan  and  Tortworth  were  investigated  for  size-independent  variation  within  and  between  samples 
using  the  multivariate  technique  of  Principal  Component  Analysis  (PCA);  the  relationships  between 
the  continuous  variates,  defined  above,  are  described  by  a correlation  matrix  from  which  the 
appropriate  eigenvalues  and  eigenvectors  have  been  extracted.  The  rib  counts,  defined  as  the  total 
number  of  costae,  for  all  three  samples  are  displayed  as  frequency  polygons  (Text-figs  4 and  5) 
compared  using  the  non-parametric  Kolmogorov-Smirnov  test,  whilst  the  rib  strength  (height/ 
width  ratio  calculated  as  a percentage)  was  similarly  investigated  by  histograms  together  with 
parametric  and  non-parametric  inferential  statistics  (Text-figs  6 and  7).  Three  features  of  shell 
morphology  yielded  taxonomically  significant  results:  (i)  size-independent  shape  variation  between 
samples  of  valve  exteriors,  (ii)  the  total  number  of  ribs,  and  (iii)  the  strength  of  ribs. 


DOYLE  ET  A L. : UPPER  LLANDOVERY  BRACHIOPOD 


441 


text-fig.  2.  Locality  details  and  stratigraphies  for  the  Eocoelia- bearing  horizons  sampled  in  the  West  of  Ireland 

(a)  and  Girvan,  SW  Scotland  (b). 


442 


PALAEONTOLOGY.  VOLUME  34 


text-fig.  3.  Location  of  measurements  made  on  the  exteriors  (a)  and  ventral  (b)  and  dorsal  (c)  interiors  of 
Eocoelia.  Abbreviations  and  definition  of  measurements  given  in  text. 


table  1.  Matrices  of  sample  sizes.  Abbreviations:  PVE,  pedicle  valve  exterior;  PVI,  pedicle  valve  interior; 
BYE,  brachial  valve  exterior;  BVI,  brachial  valve  interior. 


Girvan  Connemara 


Locality 

Valve 

SI 

S2 

S3 

Total 

11 

12 

13 

Total 

PVE 

47 

37 

33 

117 

33 

35 

33 

101 

PVI 

15 

1 1 

18 

44 

32 

32 

32 

96 

BVE 

33 

35 

35 

102 

38 

40 

33 

111 

BVI 

25 

19 

35 

79 

33 

45 

33 

111 

Pooled  samples  of  the  Connemara,  Girvan  and  Tortworth  specimens  were  investigated  by  PCA: 
both  pedicle  and  brachial  valve  exteriors  and  interiors  were  analysed  with  reference  to  the  variates 
defined  above.  The  investigation  of  comparative  internal  morphology,  with  reference  to  the 
following  variates  - si,  mw,  mb,  bl  and  In  for  brachial  valves  and  si,  mw,  lc,  me,  sc  and  mt  for  pedicle 
valves  - yielded  no  apparent  differences  between  the  three  samples  when  each  specimen  was  plotted 
relative  to  the  second  and  subsequent  (size-independent)  eigenvectors.  The  Irish  specimens  have 
markedly  larger  scores  on  the  first  eigenvector,  confirming  their  relatively  larger  size.  However, 
multivariate  examination  of  the  valve  exteriors  based  on  the  variates  si,  mw  and  pm  suggests  the 
samples  may  also  be  differentiated  with  reference  to  their  scores  on  the  second  eigenvector  (direction 
cosines:  —0  278,  —0423  and  0 862)  of  this  analysis;  the  Irish  specimens  had  significantly  lower 
scores  on  this  eigenvector  indicating  an  outline  with  a maximum  width,  on  average,  nearer  the 
posterior  margin  (Text-fig.  8). 

Significant  differences  in  the  rib  counts  were  detected  between  the  Girvan  material  and  the 
specimens  from  both  Connemara  and  Tortworth  (Text-fig.  5).  The  Tortworth  sample  appears  to 


DOYLE  ET  AL.\  UPPER  LLANDOVERY  BRACHIOPOD 


443 


text-fig.  4.  Frequency  polygons  of  total  rib  numbers  on  valves  of  E.  curtisi  from  Connemara,  Tortworth  and 

Girvan. 


TORTWORTH 

CONNEMARA 


text-fig.  5.  Comparison  of  the  cumulative  frequency  polygons  of  the  total  rib  numbers  on  valves  of  E.  curtisi 

from  Connemara,  Tortworth  and  Girvan. 

plot  between  the  Irish  and  Scottish  samples  on  the  frequency  polygon  (Text-fig.  4)  and  significant 
differences  were  detected  using  the  Kolmogorov-Smirnov  test  (at  1 % level)  between  it  and  the 
material  from  Connemara  (D  = 0 718)  and  Girvan  ( D = 0-620).  Although  Ziegler  (1966,  p.  530) 
considered  the  modal  rib  density  did  not  appear  to  behave  consistently  with  time,  despite  the  small 
samples  in  many  collections,  there  is  in  fact  a decrease  in  the  number  of  ribs  with  time  along  this 
part  of  the  lineage:  a trend  true,  in  general  terms,  for  the  lineage  as  a whole.  Moreover,  Ziegler’s 
claim  that  the  stratigraphically  older  E.  hemisphaerica  (reported  modes  of  14  and  16)  has  fewer  ribs 
than  E.  intermedia  (reported  modes  of  16  and  18)  is  not  supported  by  the  data  in  his  table  3.  Larger 
samples  and  counts  of  discrete  rather  than  grouped  rib  numbers  may  help  tighten  this  putative 


444 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  6.  Frequency  polygons  of  rib-strength  indices  for  brachial  valves  of  E.  curtisi  from  Girvan,  Tortworth 

and  Connemara. 


text-fig.  7.  Cumulative  frequency  polygons  of  rib-strength  indices  for  brachial  valves  of  E.  curtisi  from 

Girvan,  Tortworth  and  Connemara. 


DOYLE  ET  A L.:  UPPER  LLANDOVERY  BRACHIOPOD 


445 


SCORES  ON  SECOND  EIGENVECTOR 

text-fig.  8.  Comparison  of  the  scores  on  the  second  eigenvector  (direction  cosines:  —0-278,  —0-423,  0-862) 
for  a PCA  of  variates  si,  mw  and  pw  for  brachial  valve  exteriors  of  the  Irish  and  Scottish  Eocoelia.  The 
Connemara  specimens,  E.  c.  curtisi  have  significantly  smaller  scores  on  this  eigenvector  (D  > 0-23  at  1 % 

level  - Kolmogorov-Smirnov  test). 


trend.  Sheldon  (1987)  has  shown  that  evolutionary  reversals  are  possible  in  otherwise  unidirectional 
evolutionary  trends,  so  it  is  conceivable  that  the  overall  trend  of  loss  of  ribs  in  the  Eocoelia  lineage 
may  be  influenced  by  periods  of  no  loss  or  possible  rib  gain. 

The  rib  strength  of  the  taxa  from  Connemara,  Girvan  and  Tortworth  also  displayed  significant 
contrasts  (Text-figs  6 and  7).  Clearly,  in  view  of  the  probability  of  some  abrasion  of  the  ribs  during 
postmortem  transport  and  modification  with  compaction,  diagenesis  and  subsequent  dissolution, 
this  feature  must  be  treated  with  some  caution.  Nevertheless,  the  clear  decrease  in  rib  strength  with 
time  is  confirmed  within  the  area  of  the  lineage  investigated  here.  Data  from  the  Tortworth  (Ziegler 
1966,  table  6),  Connemara  and  Girvan  specimens  were  compared  statistically  by  F and  t tests  and 
the  rib  strengths  of  all  three  samples  were  compared  with  those  of  the  stratigraphically  older  E. 
intermedia.  But  although  the  direction  of  the  trend  is  confirmed,  the  timing  of  events  within  the 
trend  would  appear  to  be  slightly  retarded.  The  Irish  Eocoelia  ribs  are  significantly  stronger  than 
those  of  the  nominate  subspecies  from  Tortworth,  having  rib  strengths  similar  to  those  of  E. 
intermedia  from  Norbury,  whereas  the  Girvan  specimens  have  rib  strengths  similar  to  those  of  the 
stratigraphically  younger  E.  intermedia  from  May  Hill. 

Many  of  the  significant  differences  may  be  artefacts  of  sample  comparisons  of  discrete  and 
spatially  isolated  segments  of  a gradualist  lineage.  Further  interpolation  within  the  lineage  will 
clearly  strain  the  existing  Linnean  framework  established  for  Eocoelia  and  will  require  a complete 
revision  of  its  taxonomy  or  the  recognition  of  categories  of  lesser  rank  than  the  subspecies  (see  also 
Sheldon  1987). 


446 


PALAEONTOLOGY,  VOLUME  34 


REFINEMENT  OF  THE  EOCOELIA  LINEAGE 

The  Eocoelia  lineage,  first  established  in  detail  by  Ziegler  (1966)  and  later  modified  by  Cocks  (1971), 
has  more  recently  been  summarized  by  Bassett  (1984)  in  its  entirety.  Cocks  et  al.  (1984)  have,  in 
revising  the  type  Llandovery  Series,  documented  the  lower  part  of  the  lineage,  summarized  on  Text- 
figure  9. 

Ziegler  (1966)  identified  a number  of  clear  morphological  trends  during  the  phytogeny  of 
Eocoelia : (i)  strengthening  of  the  articulating  mechanisms  with  a trend  towards  deeper  fossettes, 
stronger  hinge  plates  and  more  robust  teeth;  (ii)  reduction  in  the  development  of  lips  and 
deflections;  and  (iii)  decline  in  rib  strength. 

All  three  samples  investigated  have  well-developed  crural  fossettes,  strong  hinge  plates  and  robust 
teeth,  but  umbonal  chambers  are  lacking.  Although  these  features  are  difficult  to  compare 
quantitatively,  the  samples  from  Girvan,  Tortworth  and  the  West  of  Ireland  are  consistent  with 
those  of  E.  curtisi  Ziegler,  1966,  confirming  their  inclusion  in  that  species. 

Fourteen  percent  (N  = 180)  of  pedicle  and  brachial  valves  from  the  West  of  Ireland  possessed  a 
deflection  whereas  only  0-01  % (N  = 220)  of  pedicle  and  brachial  valves  from  Girvan  possessed  the 
same  feature.  Clearly  this  interpolated  trend  is  contrary  to  that  seen  in  the  lineage  as  a whole  where 
there  is  an  increase  in  the  development  of  the  deflection  and  lip.  Although  Ziegler  (1966),  in 
establishing  a trend  in  this  aspect  of  the  Eocoelia  shell,  implied  that  the  development  of  such  features 
is  not  related  to  the  size  of  the  individual,  deflections  are  in  fact  most  commonly  recorded  from 
larger  specimens.  In  the  samples  investigated  by  Ziegler  ( 1966),  the  stratigraphically  older  species  are 


LU 

1 


Graptolite 

Zones 


LITHOSTRATIGRAPHY 


Llandovery  Connemara  Girvan  Tortworth 


Evolutionary  Brachiopod  Lineages 


Eocoelia 


Stricklandud  Pentamerid 


O 

O 


> 

cc 

LU 

B 

Q 

Z 

< 


Centrifugus 

Crenulata 


Cwernfelen 

Fm. 


Lettergesh  Fm. 
Gowlaun  Mbr. 


Tonalee  Fm. 


Griestoniensis 


Crispus 


Turriculatus 


Kilbride 

Fm. 


Sedgwickii 


Convolutus 


Cerig  Fm. 


Wormwood  Fm. 


Rhydings  Fm. 


Knockgardner 


Blair  Shale 


Tortworth 

Beds 


Drumyork 

Flags 


Up.  Trap 


Damery  Beds 


Lauchlan  Fm. 


Proto.  Grits 


Penkill  Fm. 


U.C.G. 


Max.  M.st. 


f'/ood  Burn  Fm 


L.C.G. 


Pencleuch 

Shale 


IT 

® i 

E i 
£ ' 


4-  UJ  + 


„t 

It 


text-fig.  9.  Lithostratigraphy  of  the  Connemara,  Girvan  and  Tortworth  successions  together  with  brachiopod 
lineages  of  correlative  value  displayed  relative  to  the  current  graptolite  biostratigraphy  and  chronostratigraphy 
for  relevant  parts  of  the  lower  Silurian.  Abbreviations:  L.C.G.,  Lower  Camregan  Grits;  Max.  Mst., 
Maxwellston  Mudstones;  U.C.G.,  Upper  Camregan  Grits;  Proto.,  Protovirgularia,  Up.,  Upper. 


DOYLE  ET  AL.:  UPPER  LLANDOVERY  BRACHIOPOD 


447 


generally  larger  than  those  occurring  high  in  the  lineage.  Ziegler  (1966,  table  7)  reported  a total 
absence  of  deflections  on  the  shells  of  E.  curtisi.  The  Irish  samples  are  however  larger  (mean  widths 
of  110  and  114mm  for  dorsal  and  ventral  exteriors,  respectively)  than  the  largest  mean  width 
(6  68  mm)  reported  in  Ziegler  (1966,  table  5). 

Within  the  Eocoelia  lineage  (Ziegler  1966)  the  transition  between  E.  intermedia  and  E.  curtisi  is 
taken  to  occur  in  the  lowest  part  of  the  turriculatus  Biozone  at  a level  correlated  with  the 
Aeronian/Telychian  junction  (Cocks  et  al.  1984).  Therefore  implicit  in  the  definition  of  this 
boundary  is  the  coincidence  of  the  base  of  the  turriculatus  Biozone  with  the  base  of  the  Telychian. 
In  the  type  area  of  the  Llandovery  Series  diagnostic  graptolite  and  shelly  fossils  are  rare  or  absent 
at  and  adjacent  to  the  Aeronian/Telychian  stratotype  boundary.  Graptolites  are,  in  fact,  absent 
within  the  basal  part  of  the  Telychian  in  the  type  area,  although  faunas  considered  diagnostic  of  the 
lower  half  of  the  turriculatus  Biozone  (Cocks  et  at.  1984,  p.  168)  are  reported  10  km  from  the 
stratotype  section  (Temple  1988,  p.  879). 

Ascending  the  type  section,  E.  curtisi  is  first  encountered  in  the  lower  part  of  the  Cerig  Formation, 
35  m above  the  basal  Telychian  stratotype  (Cocks  et  al.  1984,  fig.  67),  although  it  is  assumed  to 
occur  throughout  the  lower  part  of  the  formation  (Cocks  et  al.  1984,  fig.  69),  and  thus  within  the 
lower  part  of  the  turriculatus  Biozone.  Cocks  et  al.  (1984,  p.  168)  considered  that  the  distribution 
of  the  relevant  Eocoelia  species  and  graptolites  in  the  Penwhapple  Burn  section,  near  Girvan  (Cocks 
and  Toghill  1973)  confirmed  the  coincidence  of  the  base  of  the  Telychian  with  the  base  of  the 
turriculatus  Biozone.  However,  at  Girvan  specimens  hitherto  assigned  to  E.  curtisi  (see  Cocks  and 
Toghill  1973)  and  assigned  here  to  E.  curtisi  immatura  subsp.  nov.  occur  with  Pentamerus  oblongus 
in  the  Lower  Camregan  Grits.  Although  Cocks  and  Toghill  (1973)  do  not  record  an  in  situ  graptolite 
fauna  from  the  overlying  Wood  Burn  Formation,  some  slabs  in  the  Gray  Collection  (British 
Museum  of  Natural  History)  from  the  Penkill  locality  suggest  a correlation  with  the  upper 
sedgwickii  Biozone  (Cocks  and  Toghill  1973,  p.  226).  The  succeeding  Maxwellston  Mudstones 
contain  a lower  turriculatus  Biozone  fauna  (Cocks  and  Toghill  1973,  p.  227).  Thus,  rather  than 
suggesting  E.  curtisi  occurs  with  turriculatus  Biozone  graptolites,  the  Girvan  section  indicates  a co- 
occurrence with  graptolites  of  the  sedgwickii  Biozone. 

Clearly,  the  lack  of  graptolite  control  across  the  Aeronian/Telychian  boundary  stratotype  invites 
correlation  of  the  upper  part  of  the  Wormwood  Formation  with  either  the  lower  turriculatus  or 
upper  sedgwickii  biozones.  However,  in  the  absence  of  more  equivocal  faunal  control  in  the  type 
area,  the  faunal  data  from  Girvan  suggest  the  base  of  the  Telychian  may  be  better  correlated  with 
a horizon  within  the  upper  part  of  the  notional  sedgwickii  Biozone.  Moreover  there  is  a gap  of  some 
65  nr  in  the  Eocoelia  lineage  between  the  last  occurrence  of  E.  intermedia  in  the  upper  part  of  the 
Wormwood  Formation  and  the  first  occurrence  of  E.  curtisi  in  the  Cerig  Formation.  If  the  lineage 
is  as  cosmopolitan  as  previous  and  current  documentation  suggests,  then  forms  similar  to  E.  c. 
immatura , together  with  graptolites  of  the  sedgwickii  Biozone,  might  be  expected  within  this  faunal 
hiatus. 

North  of  the  Girvan  valley,  in  the  Craighead  inlier  Cocks  and  Toghill  (1973)  have  documented 
the  co-occurrence  of  E.  curtisi  (E.  c.  immatura  herein)  and  Pentamerus  oblongus  within  the  Lower 
Camregan  Grits.  Extension  of  the  pit  in  Craigfin  Wood  (Cocks  and  Toghill  1 973,  p.  217)  has  yielded 
a new  fauna  in  higher  strata:  a species  of  Pentameroides  occurs  with  a number  of  poorly  preserved 
specimens  assigned,  on  the  basis  of  their  outlines  and  rib  numbers,  to  E.  cf.  curtisi  curtisi.  Poor 
exposure  and  complex  faulting  in  this  part  of  the  inlier  presents  considerable  stratigraphical 
diflficulties;  nevertheless,  the  co-occurrence  of  Pentameroides  and  a form  approximating  to  the 
nominate  subspecies  of  E.  curtisi  supports  the  correlations  presented  in  Text-figure  9. 

In  the  west  of  Ireland,  E.  curtisi  curtisi  occurs  with  Costistricklandia  lirata  and  Pentameroides 
within  the  Kilbride  Formation,  presumably  near  the  top  of  its  range.  Although  no  diagnostic  fossils 
are  present  in  the  overlying  Tonalee  Formation  (Doyle  et  al.  1990)  the  succeeding  Benbeg 
Mudstones  contain  crenulata  Biozone  graptolites  (Rickards  1973). 


448 


PALAEONTOLOGY.  VOLUME  34 


SYSTEMATIC  PALAEONTOLOGY 

Family  trigonirhynchiidae  McLaren,  1965 

Genus  eocoelia  Nikiforova,  1961  (in  Nikiforova  and  Andreeva  1961) 

Remarks.  Cocks  (1978,  p.  149)  transferred  Eocoelia  from  its  traditional  site  within  the  Atrypida,  on 
the  basis  of  an  undescribed  species  of  Eocoelia , from  the  Idwian  (Aeronian)  of  Shropshire,  with 
similarities  to  Rostricellula. 


Eocoelia  curtisi  curtisi  Ziegler,  1966 

Text-fig.  10 

1867  Atrypa?  hemisphaerica  J.  de  C.  Sowerby;  Davidson,  p.  136  (pars),  pi.  13,  figs  24-30a,  non  fig. 
23.’ 

1966  Eocoelia  curtisi  Ziegler,  p.  537  (pars),  pi.  83,  figs  7 and  8;  pi.  84,  figs  12-17. 

Holotype.  OUM  C3241 ; an  internal  mould  of  a pedicle  valve  from  the  Damery  Beds  (Telychian)  of  the 
Tortworth  Inlier,  Gloucestershire;  pi.  84,  figs  15,  16,  17  of  Ziegler  1966. 

Material.  About  200  pedicle  valves  and  200  brachial  valves,  all  virtually  complete,  none  conjoined. 

Diagnosis.  Nominate  subspecies  of  E.  curtisi  with  7-16  (mode  1 1 - Connemara  or  12  - Tortworth) 
strong  ribs  developed  on  brachial  valve  exteriors;  maximum  width  posterior  to  midvalve  length  and 
rib  strengths  about  one-quarter. 

Description 

Exterior.  Medium-sized,  planoconvex  valves  of  transversely  subquadrate  to  subelliptical  outline  with 
maximum  width  posterior  to  mid-valve  length.  Hinge  line  about  four-fifths  maximum  width,  cardinal 
extremities  obtuse  and  rounded.  Pedicle  valve  about  three-quarters  as  long  as  wide  and  about  one-quarter  as 
deep  as  long;  anterior  and  lateral  profiles  convex  medianly  but  in  later  growth  stages  growth  vectors  change 
to  produce  anterolateral  flattening.  Maximum  depth  occurs  between  one-fifth  and  two-fifths  valve  length. 
Brachial  valve  about  three-quarters  as  long  as  wide,  essentially  flat  with  faint  median  sulcus  and  flatly  convex 
flanks.  Deflection  of  valve  profile  present  on  14%  of  pedicle  and  brachial  valves  ( N = 180).  Ornament  of  strong 
costae  of  evenly  rounded,  semicircular  profile,  numbering  7-15  on  1,3,2,20,34,29,12,7,2  valves  and  with 
mean  (variance)  rib  strength  (height/width  * 100)  of  26-4  (43-5)  for  40  brachial  valves;  costae  subdued  or  absent 
posterolaterally.  Concentric  growth  lines  absent  posteriorly  but  accentuated  anteriorly. 

Ventral  interior.  Delthyrial  chamber  moderately  deep  with  faint  pedicle  callist  rarely  developed  in  posterior 
half.  Large  cyrtomatodont  teeth,  oval  to  triangular  in  dorsal  view  with  rounded  anterior  surfaces.  Dental  plates 
absent;  teeth  attached  directly  to  shell  wall.  Large  fossettes  cut  deeply  into  medial  face  of  teeth  extending  into 
shell  wall.  Muscle  scars  not  impressed. 

Dorsal  interior.  Socket  plates  large,  well  developed,  almost  rectangular  in  ventral  view,  diverging  at  55-75 
degrees  and  supported  posteriorly  on  broad,  raised  notothyrial  platform ; cardinal  process  very  rarely  ( < 1 %) 
present.  Sockets  deep,  conical  and  widely  divergent.  Median  ridge  arising  anterior  to  notothyrial  platform  and 
extending  to  about  one-half  valve  length.  Muscle  scars  feebly  impressed. 

Measurements  and  statistics 


Brachial  valve  exteriors 


Variates 

si 

mw 

pm 

Sample  size 

110 

111 

no 

Means 

7-71 

11-0 

2-46 

Variance-covariance  matrix 

2-29 

2-87 

0-58 

4-92 

0-74 

0-39 

DOYLE  ET  A L.:  UPPER  LLANDOVERY  BRACHIOPOD 


449 


J K L 


text-fig.  10.  Eocoelia  curtisi  curtisi  Ziegler,  from  the  lower  part  of  the  Kilbride  Formation,  north  Connemara. 
a,  external  mould  of  brachial  valve,  JMM  BrlOOO,  x 3.  b,  external  mould  of  brachial  valve,  JMM  BrlOOl,  x 3. 
c,  latex  cast  of  pedicle  valve  exterior,  JMM  Brl002,  x 2.  d,  latex  cast  of  pedicle  valve  exterior,  JMM  Brl003,  x 3. 
E,  latex  cast  of  brachial  valve  interior,  JMM  Brl004,  x 3.  f,  internal  mould  of  pedicle  valve,  JMM  Brl005,  x 2. 
G,  internal  mould  of  pedicle  valve,  JMM  Brl006,  x 2.  h,  internal  mould  of  pedicle  valve,  JMM  Brl007,  x 3. 
i,  internal  mould  of  brachial  valve,  JMM  Brl008,  x 3.  J,  latex  cast  of  pedicle  valve  interior,  JMM  Brl009,  x 3. 
k,  latex  cast  of  pedicle  valve  interior,  JMM  Br  1010,  x 3.  L,  internal  mould  of  brachial  valve,  JMM  BrlOl  1,  x 3. 


450 


PALAEONTOLOGY.  VOLUME  34 


Brachial  valve  interiors 


Variates 

si 

mw 

mb 

bl 

In 

Sample  size 

104 

105 

1 1 1 

111 

111 

Means 

8-00 

10-8 

1 90 

1-24 

0-82 

Variance-covariance  matrix 

1-76 

2-47 

0-43 

0-23 

013 

4-98 

0-81 

0-40 

019 

0-20 

009 

0-04 

0-08 

004 

0-03 

Pedicle  valve  exteriors 

Variates 

si 

mw 

pm 

Pt 

Sample  size 

98 

100 

100 

100 

Means 

8-06 

1 14 

2-82 

2-80 

Variance-covariance  matrix 

2-06 

2-17 

0-61 

0-57 

3-95 

0-66 

0-53 

0-32 

0-23 

0-36 

Pedicle  valve  interiors 

Variates 

si 

mw 

lc 

me 

sc 

mt 

Sample  size 

96 

96 

96 

96 

96 

96 

Means 

8-21 

11-2 

1-23 

2-01 

1 09 

2-42 

Variance-covariance  matrix 

2-07 

2-37 

0-18 

0-35 

0-21 

0-44 

4-02 

0-25 

0-54 

0-26 

0-65 

006 

0-06 

004 

0-07 

015 

0-06 

0 16 

0-05  007 

0-21 


Remarks.  The  description  of  E.  curtisi  curtisi,  presented  here,  is  based  exclusively  on  material  from 
the  lower  part  of  the  Kilbride  Formation,  which  crops  out  along  the  northern  margin  of 
Connemara.  The  Irish  specimens  are  considered  morphologically  identical  to  the  type  and  topotype 
material  of  the  nominate  subspecies  from  Tortworth  except  for  the  development  of  the  ribs.  The 
ribbing  strengths  of  the  various  E.  curtisi  morphs  have  been  discussed  above.  However,  analysis  of 
the  rib  counts  of  the  Tortworth  and  Connemara  specimens  presents  taxonomic  difficulties.  A 
Kolmogorov-Smirnov  test,  as  noted  above,  indicates  a significant  difference  between  the  two 
frequency  distributions.  The  Irish  material  has  a modal  value  of  11  ribs,  that  from  Tortworth  has 
a mode  of  12.  However,  the  sample  from  Tortworth  is  disproportionately  smaller  than  that  from 
Ireland.  Moreover  it  is  probable  that  the  Connemara  specimens  are  from  slightly  younger  horizons 
than  those  from  Tortworth,  thus  confirming  the  trend  of  decreasing  rib  number  with  decreasing 
time.  Since  the  Irish  E.  curtisi  agrees  in  all  other  aspects  with  the  nominate  subspecies  it  is  not 
separated  on  the  basis  only  of  the  modal  rib  counts.  However,  it  may  be  suggested  the  two  represent 
chronological  morphs  of  the  same  subspecies  which  a more  rigorous  investigation  of  more  material 
may  confirm  or  reject. 

Eocoelia  curtisi  Ziegler,  1966  immatura  subsp.  nov. 

Text-fig.  1 1 

1867  Atrypa?  hemisphaerica  J.  de  C.  Sowerby;  Davidson,  p.  136  (pars),  pi.  13,  figs  25,  27-30. 

1973  Eocoelia  curtisi  Ziegler;  Cocks  and  Toghill,  p.  225,  pi.  3,  figs  1-3. 

Name.  Latin  immature a youthful  morphological  characteristics. 


DOYLE  ET  AL. : UPPER  LLANDOVERY  BRACHIOPOD 


451 


M N O P 

text-fig.  1 1.  Eocoelia  curtisi  Ziegler  immatura  subsp.  nov.  from  the  Lower  Camregan  Grits,  Penwhapple  Burn, 
Girvan.  a,  external  mould  of  brachial  valve,  JMM  Br  1012,  x 3.  B,  external  mould  of  brachial  valve,  JMM 
Br  1013,  x 2.  c,  external  mould  of  brachial  valve,  JMM  Brl014,  x 2.  d,  external  mould  of  brachial  valve,  JMM 
Br  1015,  x3.  e,  latex  cast  of  pedicle  valve  exterior,  JMM  Br  1016,  x 2.  F,  latex  cast  of  pedicle  valve  exterior, 
JMM  Br  1017,  x 3.  G,  latex  cast  of  brachial  valve  interior,  JMM  Br  1018,  x 3.  h,  latex  cast  of  brachial  valve 
interior,  JMM  Brl019,  x 2.  i,  internal  mould  of  pedicle  valve,  JMM  Brl020,  x 2.  j,  internal  mould  of  pedicle 
valve,  JMM  Brl021,  x 2.  k,  internal  mould  of  brachial  valve,  JMM  Brl022,  x 2.  l,  internal  mould  of  brachial 
valve,  JMM  Brl023,  x 2.  m,  latex  cast  of  pedicle  valve  interior,  JMM  Brl024,  x 2.  n,  latex  cast  of  pedicle  valve 
interior,  JMM  Brl025,  x 2.  o.  External  mould  of  pedicle  valve,  JMM  Brl026,  x 2.  p,  external  mould  of  pedicle 
valve,  JMM  Brl027,  x3.  All  type  and  figured  specimens  are  deposited  in  the  James  Mitchell  Museum, 

University  College  Galway,  Ireland. 


Holotype.  JMM  Brl020;  an  internal  mould  of  a pedicle  valve  from  the  Lower  Camregan  Grits,  Penwhapple 
Burn,  Girvan,  SW  Scotland. 

Material.  About  150  pedicle  valves  and  about  180  brachial  valves,  all  virtually  complete,  none  conjoined. 

Diagnosis.  Small  subspecies  of  E.  curtisi  with  13-  19  (mode  15)  strong  ribs  developed  on  brachial 
valve  exteriors;  maximum  width  at  or  near  midvalve  length  and  rib  strength  of  about  one-third. 


452 


PALAEONTOLOGY,  VOLUME  34 


Description 

Exterior.  Small,  planoconvex  valves  of  subquadrate  outline  with  maximum  width  at  or  near  mid-valve  length. 
Hinge  line  about  three-quarters  maximum  width  with  obtusely  rounded  cardinal  extremities.  Pedicle  valve 
about  four-fifths  as  long  as  wide  and  about  one-quarter  as  deep  as  long  with  maximum  depth  at  about  one- 
third  valve  length.  Delthyrium  relatively  wide  and  open.  Brachial  valve  about  four-fifths  as  long  as  wide  and 
essentially  flat.  Ventral  and  dorsal  interareas  obsolete.  Ornament  of  relatively  strong  ribs  of  evenly  rounded 
profile  developed  over  entire  valve  surface  and  numbering  1 3-1 9 on  1 1 , 34, 40, 1 3, 4, 0, 1 valves  with  rib  strength 
of  mean  (variance)  35-8  (47-4)  for  38  brachial  valves. 


Ventral  interior.  Relatively  deep  delthyrial  chamber  flanked  by  large  cyrtomatodont  teeth,  oval  in  dorsal  view 
with  rounded  anterior  surfaces;  dental  plates  absent.  Dental  fossettes  cut  deeply  into  medial  face  of  teeth. 
Muscle  scars  not  impressed. 


Dorsal  interior.  Large,  robust  socket  plates,  elongately  rectangular  in  ventral  view  and  distal  parts  anteriorly 
divergent  on  low  notothyrial  platform.  Deep,  divergent  conical  sockets.  Broad  median  ridge  extending 
anteriorly  from  margin  of  notothyrial  platform.  Muscle  scars  not  impressed. 


Measurements  and  statistics 

Brachial  valve  exteriors 


Variates 

si 

mw 

pm 

Sample  size 

103 

103 

103 

Means 

5-61 

6-90 

2-30 

Variance-covariance  matrix 

0-73 

0-80 

0-24 

114 

0-32 

014 

Brachial  valve  interiors 


Variates 

si 

mw 

mb 

nl 

In 

Sample  size 

79 

79 

79 

79 

79 

Means 

5-84 

7-08 

1-44 

114 

0-54 

Variance-covariance  matrix 

0-82 

100 

0 12 

010 

0-05 

1-49 

01 9 

015 

0-08 

0-08 

004 

001 

004 

001 

0-01 

Pedicle  valve  exteriors 

Variates 

si 

mw 

pm 

pd 

Pt 

Sample  size 

117 

117 

1 17 

117 

117 

Means 

5-35 

6-47 

2-34 

1 62 

13-2 

Variance-covariance  matrix 

219 

1 94 

0-72 

0-52 

0-39 

2-86 

0-91 

0-69 

0-66 

0-43 

0-27 

018 

0-28 

010 

1 53 

Pedicle  valve  interiors 

Variates 

si 

mw 

lc 

me 

sc 

Sample  size 

44 

44 

44 

44 

44 

Means 

5-99 

6-80 

0-66 

1-33 

0-55 

mt 

44 

1-55 


DOYLE  ET  A L.:  UPPER  LLANDOVERY  BRACHIOPOD 


453 


Variance-covariance  matrix 


0-89 


0-7 1 
061 


013 

010 

003 


012 
01 1 
002 
003 


009 

0-07 

002 

0-01 

002 


014 

013 

002 

0-03 

0-01 

0-04 


Remarks.  The  Scottish  material,  hitherto  referred  to  E.  curtisi  by  Cocks  and  Toghill  (1973),  differs 
in  two  main  respects  from  the  nominate  subspecies.  First  the  maximum  width  is  at  or  near  the  mid- 
valve  length  and  secondly  it  has  more  and  stronger  ribs.  Taken  together,  the  morphological 
contrasts  may  be  interpreted  as  specific  differences;  however,  the  Girvan,  Connemara  and 
Tortworth  samples  are  characterized  by  well-developed  crural  fossettes,  strong  hinge  plates  and 
robust  teeth;  umbonal  chambers  are  absent.  This  association  of  characteristics  conventionally 
describes  E.  curtisi ; the  differences,  therefore,  are  accorded  only  subspecific  status. 

Acknowledgements . We  thank  A.  Davis  for  assistance,  P.  Powell  for  access  to  material  in  the  Oxford  University 
Museum  and  W.  S.  McKerrow  for  many  wide-ranging  discussions.  Doyle  and  Hoey  were  financed  by 
Postgraduate  Fellowships  at  University  College  Galway  and  Harper  is  grateful  to  the  Royal  Irish  Academy  for 
help  with  field  expenses. 


bassett,  m.  G.  1984.  Lower  Palaeozoic  Wales -a  review  of  studies  in  the  past  25  years.  Proceedings  of  the 
Geologists'  Association , 95,  291-311. 

cocks,  l.  R.  m.  1971.  Facies  relationships  in  the  European  Lower  Silurian.  Memoires  du  Bureau  de  Recherches 
Geologicjues  et  Minieres,  73,  223-227. 

— 1978.  A review  of  British  Lower  Palaeozoic  brachiopods,  including  a synoptic  revision  of  Davidson’s 
monograph.  Monograph  of  the  Palaeontographical  Society , 131  (549),  1-256. 

— and  toghill,  p.  1973.  The  biostratigraphy  of  the  Silurian  rocks  of  the  Girvan  district,  Scotland.  Journal 
of  the  Geological  Society  of  London , 129,  209-243,  pis  1-3. 

woodcock,  n.  h.,  rickards,  R.  b.,  temple,  j.  t.  and  lane,  p.  d.  1984.  The  Llandovery  Series  of  the  type 

area.  Bulletin  of  the  British  Museum  ( Natural  History),  (Geology),  38,  131-182. 
davidson,  t.  1867.  A monograph  of  the  British  fossil  Brachiopoda.  Part  VII.  No.  II.  The  Silurian  Brachiopoda. 

Monograph  of  the  Palaeontographical  Society,  3,  89-168,  pis  13-22. 
doyle,  e.  n.  1989.  The  biostratigraphy  and  sedimentology  of  the  Lower  Silurian  (Llandovery)  rocks  of  north 
Galway.  Unpublished  Ph.D.  thesis.  National  University  of  Ireland. 

— harper,  d.  a.  t.  and  parkes,  m.  a.  1990.  The  Tonalee  fauna:  a deep-water  shelly  assemblage  from  the 
Llandovery  rocks  of  the  West  of  Ireland.  Irish  Journal  of  Earth  Sciences,  11,  127-143. 

harper,  d.  a.  t.  and  ryan,  p.  d.  1987.  PALSTAT  - a statistical  package  for  palaeontologists.  Palaeontological 
Association  and  Lochee  Publications,  Dundee,  Scotland. 
laird,  M.  G.  and  mckerrow,  w.  s.  1970.  The  Wenlock  sediments  of  northwest  Galway,  Ireland.  Geological 
Magazine , 107,  297-317. 

mclaren,  d.  j.  1965.  Family  Trigonirhynchiidae  McLaren,  n.  fam.  H559-H562.  In  moore,  r.  c.  (ed. ).  Treatise 
on  invertebrate  paleontology.  Part  H.  Brachiopoda.  Geological  Society  of  America  and  Kansas  University 
Press,  Boulder,  Colorado  and  Lawrence,  Kansas,  927  pp. 

Nikiforova,  o.  i.  and  andreeva,  o.  n.  1961.  Stratigraphy  of  the  Ordovician  and  Silurian  of  the  Siberian 
Platform  and  its  palaeontological  basis  (Brachiopods).  Biostratigraphiya  Paleozoya  Sibirskov  Platformy, 
Leningrad,  1,  1-412,  pis  1-56. 

piper,  d.  J.  w.  1972.  Sedimentary  environments  and  palaeogeography  of  the  late  Llandovery  and  earliest 
Wenlock  of  north  Connemara.  Quarterly  Journal  of  the  Geological  Society  of  London,  128,  33-51. 
rickards,  R.  b.  1973.  On  some  highest  Llandovery  red  beds  and  graptolite  assemblages  in  Britain  and  Eire. 
Geological  Magazine,  110,  70-72. 

sheldon,  p.  r.  1987.  Parallel  gradualistic  evolution  of  Ordovician  trilobites.  Nature,  330,  561-563. 
temple,  J.  T.  1988.  Biostratigraphical  correlation  and  the  stages  of  the  Llandovery.  Journal  of  the  Geological 
Society  of  London,  145,  875-879. 


REFERENCES 


454 


PALAEONTOLOGY.  VOLUME  34 


ziegler,  A.  m.  1965.  Silurian  marine  communities  and  their  environmental  significance.  Nature , 207,  270-272. 
- 1966.  The  Silurian  brachiopod  Eocoelia  hemisphaerica  (J.  de  C.  Sowerby)  and  related  species. 
Palaeontology , 9.  523-543,  pis  83  and  84. 


E.  N.  DOYLE1,  A.  N.  HOEY2  and  D.  A.  T.  HARPER 
Department  of  Geology 
University  College 
Galway,  Ireland 

Present  addresses: 

1 Department  of  Geology 
University  of  the  West  Indies 
Mona,  Kingston  7,  Jamaica 


Typescript  received  2 January  1990 
Revised  typescript  received  7 March  1990 


2 Department  of  Geology 
University  College 
Belfield,  Dublin,  Ireland 


THE  ROLE  OF  PREDATION  IN  THE  EVOLUTION  OF 
CEMENTATION  IN  BIVALVES 

by  ELIZABETH  M.  HARPER 


Abstract.  The  independent  appearance  of  many  taxa  of  cementing  bivalves  during  the  early  Mesozoic 
coincided  with  the  marked  increase  in  predation  pressure  described  by  Vermeij  (1977,  1987).  A causal  link  is 
implied  by  experimental  work  in  which  predators  were  offered  the  choice  of  byssate  or  cemented  bivalve  prey: 
cementation  confers  a significant  selective  advantage  by  inhibiting  manipulability.  The  example  illustrates  the 
potential  value  to  palaeontology  of  studies  in  behavioural  ecology. 

Epifaunal  bivalves  attach  to  the  substratum  by  two  means:  cementation  by  one  valve  or,  more 
commonly,  anchorage  by  byssal  threads  produced  by  the  foot.  Yonge  (1962)  believed  that  most,  if 
not  all,  living  bivalves  possess  a byssus  in  the  larval  stage,  and  that  this  structure  was  retained  in 
some  adults,  for  example  the  Mytilacea  and  the  Arcacea,  by  neoteny.  It  would  seem  that  the 
cemented  habit  in  bivalves  was  evolved  in  stocks  already  possessing  a functional  adult  byssus; 
indeed  most  living  cementing  bivalves,  e.g.  the  Spondylidae  and  Hinnites , pass  through  a byssate 
stage  in  early  ontogeny. 


EXPERIMENTAL  WORK 

A series  of  experiments  was  designed  to  establish  the  relative  vulnerability  to  predation  of  byssate 
and  cemented  bivalve  prey.  Asteroid  and  crustacean  predators  were  offered  the  choice  of  bivalves 
attached  both  bysally  and  by  cementation.  Mytilus  edulis  was  used  for  both  prey  types,  so  that  any 
preference  expressed  would  be  due  to  mode  of  attachment  only,  rather  than  on  the  basis  of  different 
nutritional  quality.  Mussels  with  established  byssal  threads  were  collected  intertidally  in 
Dunstaffnage  Bay,  Oban,  and  cementation  was  simulated  using  an  epoxy  resin  (Araldite 
Rapid  - Ciba  Geigy)  to  fix  the  shell  by  one  valve  to  large  blocks  of  substratum.  These  ‘cemented’ 
Mvti/us  fed  normally  and  even  produced  superfluous  byssus  threads  and  hence  behaved  identically 
to  the  byssate  individuals.  Many  byssate  individuals  were  daubed  with  epoxy  in  order  to  monitor 
any  inhibitory  effect  on  predator  behaviour  (e.g.  masking  metabolite  cues  from  the  prey):  no  such 
effect  was  apparent.  Treated  and  untreated  specimens  were  eaten  in  equal  proportions. 

The  experiments  were  run  in  outdoor  running  seawater  tanks  (1-5  x 0-8  m),  each  set  up  with  a 
random  distribution  of  the  byssate  and  ‘cemented’  prey.  A number  of  individuals  of  Asterias 
ruhens , Cancer  pagur us  or  Carcinus  maenas  were  introduced  into  each  tank,  having  previously  been 
starved  for  at  least  four  days.  Regular  observations  were  made  on  the  feeding  behaviour  of  the 
predators  and  any  prey  item  taken  was  replaced  with  an  identically  attached  individual.  Hence  the 
relative  numbers  of  prey  types  were  held  constant. 


RESULTS 

If  cemented  and  byssate  prey  were  indistinguishable  to  predators,  one  might  expect  that  they  would 
be  eaten  in  the  proportions  in  which  they  occur  in  the  tank  (the  null  hypothesis).  The  results  were 
in  fact  very  different:  a much  higher  proportion  of  prey  taken  was  byssate  (see  Text-fig.  1).  Chi- 
squared  one-sample  analysis  of  these  results  reveals  that  the  preference  for  byssate  prey  over 
cemented  was  highly  significant,  rejecting  the  null  hypothesis  for  Asterias  and  Cancer  (P  <g  0-001), 


| Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  455-460.| 


© The  Palaeontological  Association 


456 


PALAEONTOLOGY,  VOLUME  34 


TOTAL  NO. 

NO. 

NO. 

NO. 

NO. 

PREDATOR 

PREY 

EXPECTED 

BYSSATE 

CEMENTED 

PULLED 

P 

TAKEN 

OF  EACH 

EATEN 

EATEN 

FREE 

Asterias  rubens 

121 

60.5 

95 

11 

15 

«0.001 

Cancer  pagurus 

132 

66 

96 

7 

29 

«0.001 

Carcinus  maenas 

27 

13.5 

19 

4 

4 

<0.05 

text-fig.  1.  Experimental  results  of  choice  trials.  Statistical  analyses  by/2.  (All  ‘cemented’  prey  that  was  pulled 
free  was  treated  in  analysis  as  ‘cemented’.)  The  null  hypothesis  that  byssate  and  cemented  prey  are  equally 
vulnerable  to  predation  is  rejected  for  Asterias  and  Cancer  (P  0 001),  and  for  Carcinus  (P  < 0 05).  The  use 

of  the  binomial  test  confirms  this  significance. 


and  for  Carcinus  (P  < 0 05).  Binomial  analysis  was  also  employed  in  order  to  verify  the  significance 
and  produced  similarly  significant  levels.  A number  of  the  ‘cemented’  bivalves  were  pulled  free  and 
eaten.  Statistically  these  were  treated  by  including  them  with  eaten  ‘cemented’  prey,  as  Feifarek 
(1987)  has  demonstrated  that  during  predation  in  the  natural  environment  the  right  valve  of 
Spondylus  americanus  may  be  broken  from  the  substratum. 

Observations  showed  that  prey  types  were  encountered  according  to  their  relative  numbers  in  the 
tank.  Rejection  of ‘cemented’  prey  was  rapid,  the  predator  moving  on  to  tackle  another  individual. 
Some  of  the  predators  employed  unorthodox  methods  of  entry  into  the  ‘cemented’  mussels.  Instead 
of  chipping  in  the  manner  described  by  Elner  and  Hughes  (1978),  Carcinus  snipped  along  the 
ligament  between  the  two  valves  without  damaging  them;  Asterias  broke  valves  in  three  instances. 
Hancock  (1965)  has  also  reported  Asterias  damaging  mussels  that  were  difficult  to  open. 


DISCUSSION 

Both  predator  groups  used  in  this  experiment  need  to  manipulate  their  prey  to  feed.  Chelate 
crustaceans  use  the  chelae  to  assess  the  size  of  their  prey  and  to  locate  weak  points  for  attack.  The 
rock  lobster  Jasus  edwardsii , feeding  on  detached  Ostrea  lutraria , first  holds  the  prey  vertically  and 
then  reverses  it  (Hickman  1972).  In  the  tanks  both  Cancer  and  Carcinus  were  observed  to  grasp  the 
prey  items  in  the  master  chela,  rotating  them  around  before  pressure  was  applied  to  crush  the  valves. 
Asterias  encountering  Mytilus  moves  the  prey  so  that  the  ventral  valve  margins  ol  the  shell  are 
opposite  its  own  oral  region.  Asteroids  feed  on  bivalves  by  pulling  the  two  valves  apart  with  their 
arms  and  inserting  stomach  lobes  in  between  the  valves  into  the  prey,  thus  feeding  extraorally.  In 
assuming  the  classic  humped  feeding  position,  the  asteroid  pulls  the  bivalve  into  a vertical  position. 

These  results  may  be  interpreted  in  terms  of  optimal  foraging,  as  described  by  Krebs  and  Davies 
(1981 ),  whereby  predators  are  shown  to  choose  prey  that  maximize  the  energy  yield  against  energy 
expended  to  locate  and  subjugate  it.  The  ‘cemented’  bivalves  are  less  easy  to  manipulate  than  are 
those  attached  by  a flexible  byssus.  Hence  the  effort  required,  and  thus  energy  expended  by  the 
predator,  is  higher  when  dealing  with  cemented  prey.  Where  byssate  and  cemented  prey  have  the 


HARPER:  PREDATION  AND  BIVALVE  CEMENTATION 


457 


same  energy  yield,  it  is  preferable  in  terms  of  net  energy  gain  for  the  predator  to  take  the  former. 
The  unorthodox  feeding  methods  employed  by  some  of  the  Aslerias  and  Carcinus  may  reflect  a 
‘ learned ' response  to  deal  with  suboptimal  prey.  Cunningham  ( 1 983)  reported  that  Carcinus  maenas 
has  a very  rapid  learning  ability  of  altered  feeding  tactics. 

Anecdotal  evidence  from  the  literature  further  demonstrates  the  advantages  conferred  by 
cementation  on  predation  resistance.  Octopus  dolfleini  prefers  not  to  eat  the  cemented  rock  scallop, 
Hinnites  giganteus , despite  its  presence  close  to  the  den  (Hartwick  et  al.  1981),  whilst  crustaceans 
feeding  on  oyster  spat  are  able  to  take  a larger  size  of  detached  than  of  attached  spat  (Mackenzie 
1970;  Elner  and  Lavoie  1983).  Feifarek  (1987)  detached  Spondylus  americanus  and  transplanted 
them  into  shallow  water  where  they  suffered  a much  higher  mortality  than  on  the  reef.  He 
attributed  this  to  a higher  vulnerability  in  shallow  water,  but  it  may  equally  well  be  interpreted  as 
due  to  the  decreased  predator  resistance  of  loss  of  attachment.  Seastars  cause  extensive  damage  to 
oyster  shell  fisheries  (Galtsoff  and  Loosanoff  1939),  but  commercially  spat  are  detached  at  a very 
early  stage  in  order  to  facilitate  their  harvest. 

Although  it  is  clearly  possible  for  predators  to  eat  cemented  bivalves,  the  difficulty  of 
manipulation  compared  with  byssally  attached  bivalves,  with  their  more  flexible  attachment,  makes 
them  less  energetically  favourable  prey.  It  would  seem  intuitively  obvious  that  a bivalve  which 
becomes  adapted  for  cementation  will  be  selected  for  over  evolutionary  time. 


IMPLICATIONS  IN  THE  FOSSIL  RECORD 

More  than  sixteen  families  of  bivalved  mollusc  have  or  have  had  representatives  with  the  ability  to 
cement  to  a hard  substratum.  Adaptations  for  cementation  appear  to  have  been  acquired 
independently  in  over  twenty  clades.  Some  groups,  for  example  the  oysters  and  the  extinct  Mesozoic 
rudists,  have  been  extremely  successful  over  geological  time. 

It  is  traditional  to  view  the  habit  as  an  adaptation  to  life  in  a turbulent  environment  (Kauffman 
1969;  Yonge  1979).  Many  byssate  bivalve  groups,  however,  also  flourish  in  high  energy  conditions, 
for  example  the  Mytilacea  and  the  Arcacea.  Udhayakumar  and  Karande  (1986)  have  surveyed  the 
relative  strength  of  adhesion  of  various  biofouling  organisms;  they  showed  that  the  force  required 
to  break  the  byssus  threads  of  Myti/us  edulis  is  considerably  more  per  unit  area  than  to  sunder 
Crassostrea  cuculata.  Byssate  attachment  has  a number  of  other  advantages:  the  possibility  of 
seasonally  variable  attachment  strength  (Price  1980);  voluntary  detachment  for  mobility, 
including  secondary  larval  settlement;  and  the  ability  to  reattach  if  dislodged  accidentally. 
Cementation  denies  such  advantages.  In  fact  Nicol  (1978)  can  determine  ‘no  compelling  reason  to 
become  shell  cemented'. 

Apart  from  the  Pseudomonotidae,  some  of  which  cemented  in  the  Carboniferous  (Newell  and 
Boyd  1972),  cementation  in  bivalves  is  a post-Palaeozoic  habit.  Text-figure  2 shows  the  temporal 
distribution  of  the  first  independent  appearance  of  the  cementing  bivalve  groups.  It  appears  that  the 
Late  Triassic  and  Jurassic  were  key  times  in  the  evolution  of  the  habit.  This  pattern  is  strikingly 
coincidental  with  the  first  appearance  of  many  durivorous  predator  groups  during  the  Mesozoic  and 
their  diversification  thereafter  - the  Mesozoic  Marine  Revolution  (MMR)  described  by  Venneij 
(1977,  1987).  Palmer  (1982)  has  postulated  that  the  increase  in  shelly  epifauna  in  hardground 
communities  during  the  Mesozoic  may  be  due  to  predation  rather  than  to  scour  resistance.  Many 
notable  niolluscivores  appeared  during  that  time  (see  also  Text-fig.  2).  Although  asteroid 
echinoderms  evolved  in  the  early  Palaeozoic,  it  is  suggested  that  it  was  not  until  the  Triassic/Jurassic 
that  the  asteroids  attained  the  suckered  tube  feet  and  the  eversible  stomach  necessary  for  extraoral 
feeding  (Blake  1981 ; Gale  1987).  This  ability  to  feed  by  prising  the  valves  apart  and  extruding  the 
stomach  into  the  prey  has  made  the  modern  seastars  most  voracious  niolluscivores.  Palaeozoic 
seastars  undoubtedly  fed  upon  bivalved  molluscs  (Clark  1912),  but  probably  only  as  scavengers. 

Gastropods,  in  particular  the  drilling  muricids  and  naticids,  are  also  notable  niolluscivores. 
Drilling  in  these  gastropod  groups  becomes  prevalent  from  the  Albian  and  Aptian  stages  of  the 
Cretaceous  (Taylor,  Cleevely  and  Morris  1983;  Taylor,  Morris  and  Taylor  1986),  although  Fiirsich 


458 


PALAEONTOLOGY,  VOLUME  34 


APPEARANCE  OF  THE 
MOLLUSCIVOROUS  HABIT 
Shell  breaking  in  - 
mammals 


Gulls  & Waders 


Naticid  & Muricid 
gastropods 


Stomatopod  Crustacea 

Rays  & Skates 

Extraoral  feeding  in 
asteroids 

Brachyuran  crabs 
Pycnodontiform  & 
Seminotiform  fish 
Crushing  cephalopods 
Homaridean  lobsters 


Placodonts 


My 

20 

TERTIARY 

40 

60 

80 

CRET. 

100 

120 

140 

160 

JURASSIC 

18C 

20C 

220 

TRIAS 

240 

260 

PALAEO- 

ZOIC 

28C 

300 

EVOLUTION  OF  CEMENTATION 

Chlamys  pusio 

Etheriidae 


-Myochamidae  & 
Cleidothaeridae 


~Hinnites 


Chamidae 


◄  Chondrodontidae 

<  Prohinnites 


-’Rudists' 


<  Eopecten 

^ ' Spondylidae 

◄  Lithiotidae 

4 Dimyidae  & Atreta 


'Gryphaeidae, 
Ostreidae,Plicatulidae 
& Terquemiidae 


-Pseudomonotidae 


text-fig.  2.  On  the  right  is  the  temporal  distribution  of  the  first  appearance  of  the  cemented  habit  in 
independent  clades  in  which  the  habit  has  been  acquired,  based  on  Skelton  et  al.  (in  press),  figure  5 (data 
derived  from  personal  records,  Newell  (1969),  Waller  (1978),  Stenzel  (1971),  Skelton  (1978),  Newell  and  Boyd 
(1972)  and  Kennedy  et  al.  (1970)).  The  timing  of  the  appearance  of  various  molluscivorous  groups  over 
geological  time  is  plotted  to  the  left,  modified  from  Vermeij  (1987). 


and  Jablonski  (1984)  report  possible  gastropod  drill  holes  from  the  Triassic.  It  seems  likely  that  this 
mode  of  predation  which  involves  little  manipulation  would  not  be  hampered  by  cementation.  Their 
appearance  in  the  Cretaceous  is  not  marked  by  further  proliferation  of  cemented  taxa.  However, 
further  experiments  are  envisaged  using  gastropod  predators. 

The  experimental  evidence  described  here  gives  a strong  suggestion  that  the  appearance  of  many 


HARPER:  PREDATION  AND  BIVALVE  CEMENTATION 


459 


cemented  bivalve  taxa  at  the  same  time  as  the  start  of  the  MMR  may  not  be  coincidental.  If  not 
a primary  selective  force  favouring  the  initiation  of  cementation,  then  the  increased  predator 
resistance  must  at  least  have  been  a valuable  evolutionary  spin-off. 


Acknowledgements . The  staff  of  the  S.M.B.A.  laboratories  at  Dunstaffnage,  in  particular  pr  Alan  Ansell  and 
Mr  Clive  Comely,  are  gratefully  acknowledged  for  their  help,  supply  of  Asterias , Cancer , Carcinus  and  tank 
space.  Dr  Peter  Skelton  and  Mr  J.  Alphey  are  thanked  for  their  enthusiastic  comment,  whilst  Professor  G.  J. 
Vermeij  is  thanked  for  his  comments  on  an  earlier  version.  Dr  David  Harper  of  Sussex  University  is  gratefully 
acknowledged  for  verifying  the  statistics.  This  work  is  part  of  a NERC  studentship. 


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e.  m.  harper 

Department  of  Earth  Sciences 
The  Open  University 
Milton  Keynes  MK7  6AA 


Typescript  received  9 March  1990 
Revised  typescript  received  29  March  1990 


MORPHOLOGIC  PATTERNS  OF  DIVERSIFICATION: 
EXAMPLES  FROM  TRILOBITES 

by  MIKE  FOOTE 


Abstract.  The  morphologic  diversification  of  the  Trilobita  is  investigated  using  a Fourier  description  of  the 
cramdia  of  Cambrian  and  Ordovician  trilobites  from  North  America.  Morphologic  diversity  increases  from  the 
Early  Cambrian  to  the  Middle  Ordovician,  but  does  not  correlate  well  with  patterns  of  generic  or  familial 
diversity.  Suprageneric  taxa  of  trilobites  are  shown  objectively  to  represent  morphotypes.  Morphologic 
dispersion  among  suprageneric  taxa  and  the  distinctness  of  these  taxa  both  increase  from  the  Cambrian  to  the 
Ordovician.  This  result  agrees  with  patterns  based  on  hypostomal  morphology  (Whittington  1988a,  19886), 
and  therefore  is  not  an  artifact  of  using  cranidial  morphology.  These  patterns  are  caused  by  the  origination 
of  new  higher  taxa,  not  evolution  within  established  higher  taxa.  Higher  taxa  tend  to  retain  the  same 
morphology  once  established,  rather  than  diverging  gradually.  In  this  respect,  higher  taxa  may  be  said  to  have 
sudden  origins.  The  origination  of  higher  taxa  may  be  linked  to  the  opening  of  new  adaptive  zones,  particularly 
in  the  Early  Ordovician,  following  widespread  extinctions  of  trilobites. 

The  fossil  record  clearly  indicates  that  evolutionary  change  is  not  evenly  distributed  over  time,  but 
is  concentrated  in  episodes  of  evolutionary  radiation.  For  the  Metazoa  at  least,  the  early 
Phanerozoic  represents  the  most  important  of  these  episodes.  Yet,  despite  its  significance,  a limited 
number  of  approaches  has  been  used  to  study  this  great  diversification,  most  notably  the  analysis 
of  taxonomic  data  (e.g.  Valentine  1969;  Erwin  et  al.  1987).  Often  implicit  in  the  analysis  of 
diversification  by  ‘taxon  counting’  is  the  assumption  either  that  morphologic  diversity  can  be 
measured  by  taxonomic  diversity,  or  that  the  number  of  taxa  reflects  the  number  of  objectively 
discernible  morphotypes.  Valentine  (1969),  for  example,  used  the  assumption  that  the  separation 
among  groups  at  a higher  taxonomic  level  usually  represents  a larger  morphological  divergence  than 
that  among  groups  at  a lower  level  in  order  to  draw  conclusions  about  community  evolution  from 
temporal  patterns  in  the  appearance  of  groups  at  various  taxonomic  levels. 

Although  we  know  that  taxonomic  data  and  morphologic  data  often  correlate,  taxonomic  and 
morphologic  approaches  are  not  simply  redundant.  If  taxa  are  consistently  defined,  then  taxonomic 
data  can  tell  us  about  the  number  of  biological  units  at  a given  time.  But  if  we  want  to  know  the 
nature  of  these  units,  how  they  originate,  and  how  they  evolve  once  established,  morphologic  data 
are  clearly  necessary.  Since  form  represents  the  raw  data  of  palaeobiology,  it  is  important  to 
document  significant  events  in  the  history  of  life  from  the  standpoint  of  morphology. 

Because  the  events  of  the  early  Phanerozoic  diversification  are  concentrated  in  the  Cambrian  and 
Ordovician,  documenting  patterns  of  morphologic  evolution  associated  with  this  radiation  requires 
a well  preserved  fossil  group  that  is  diverse  and  abundant  during  these  two  periods.  Trilobites  are 
clearly  the  group  of  choice.  Although  all  skeletonized  metazoan  phyla  were  present  by  the 
Ordovician,  some  75  % of  known  Cambrian  species  were  trilobites,  while  trilobites  account  for  23  % 
of  described  Ordovician  species  (Raup  1976).  It  is  the  availability  of  trilobites,  rather  than  any 
intrinsic  property  such  as  complexity,  that  makes  them  useful  for  a case  study  in  diversification. 

This  study  has  two  principal  objectives:  (1)  to  document  patterns  of  morphologic  diversification 
in  the  Trilobita  during  the  Cambrian  and  Ordovician;  and  (2)  to  investigate  morphologic  dispersion 
within  and  among  suprageneric  taxa  of  trilobites  in  order  to  determine  the  taxonomic  level(s)  at 
which  morphologic  diversification  is  concentrated.  Although  this  paper  focuses  on  trilobites,  it  is 
important  to  keep  in  mind  that  trilobites  provide  only  a case  study.  It  is  hoped  that  the  results  may 
yield  generalizations  regarding  morphologic  radiation  when  compared  to  information  from  other 


(Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  461-485.] 


© The  Palaeontological  Association 


462 


PALAEONTOLOGY,  VOLUME  34 


groups  of  organisms  and  other  times  in  the  history  of  life.  Finally,  while  it  is  interesting  and 
important  to  test  hypotheses  regarding  the  mechanisms  and  processes  of  evolution,  it  is  necessary 
first  to  document  patterns  in  the  rough.  Therefore,  although  ecological  and  evolutionary  processes 
will  be  discussed,  the  following  analysis  is  largely  exploratory. 


MATERIAL  AND  METHODS 

Morphometric  foundations 

The  consideration  of  large  scale  patterns  of  morphologic  evolution  requires  the  establishment  of  a 
morphospace,  i.e.,  a multidimensional  lattice  of  morphologic  variables  in  which  biological  forms 
can  be  consistently  and  objectively  represented.  This  involves  (1)  the  selection  of  an  aspect  of  form 
(some  part  or  parts  of  an  organism),  and  (2)  the  means  to  describe  that  aspect  of  form.  The  choice 
of  the  part  of  the  organism  can  be  justified  a priori  (e.g.  on  ecological  grounds),  or  a posteriori  if 
patterns  of  evolution  based  on  a subset  of  morphology  seem  concordant  with  patterns  based  on  a 
more  extensive  set  of  features. 

For  trilobites,  the  cranidium  is  appropriate  for  studying  large  scale  evolutionary  patterns.  First, 
it  is  well  preserved  and  recognizable  through  time  and  across  nearly  all  taxonomic  lines.  Second,  it 
has  ecological  significance  in  reflecting  the  size  and  orientation  of  sensory  structures  such  as  eyes, 
the  style  of  moulting,  and  the  attachment  of  feeding  appendages.  Finally,  as  shown  below,  patterns 
of  cranidial  evolution  are  concordant  with  subjective  assessments  based  on  gross  morphology  and 
hypostomal  morphology. 

For  nearly  all  Cambrian  and  Ordovician  trilobites  the  cranidium,  or  ‘central  dorsal  portion  of 
cephalon  bounded  laterally  by  facial  sutures'  (Harrington  el  al.  1959,  p.  0119),  is  easy  to  define  and 
identify.  In  the  case  of  marginal  sutures  (e.g.  Harpina,  Trinucleacea),  the  lateral  bounds  of  the 
cranidium  can  be  identified  with  the  lateral  margin  of  the  cephalon.  In  some  cases  (e.g.  some 
Phacopina)  the  facial  suture  is  not  functional,  but  can  nevertheless  be  identified.  The  only  difficulty 
is  with  olenellids  and  some  agnostids,  which  lack  a facial  suture.  For  purposes  of  this  study  the 
cranidium  in  such  cases  is  operationally  defined  as  if  the  cephalon  were  bounded  by  a marginal 
suture.  This  solution  is  purely  operational,  and  the  ‘cranidium’  so  defined  obviously  does  not  have 
the  same  biologic  significance  as  the  true  cranidium.  However,  it  seems  that  for  these  few  exceptions 
it  would  be  unwise  to  discard  an  otherwise  very  useful  morphologic  system.  It  should  be  noted  that 
in  the  material  studied  here,  the  number  of  specimens  without  a definable  cranidium  is  less  than  2% 
of  the  total  sample  size.  Therefore  it  is  unlikely  a priori  that  this  limitation  would  present  a serious 
bias. 

The  question  of  morphologic  evolution  involves  the  consideration  of  descent  with  modification. 
Therefore,  one  would  ideally  hope  to  recognize  a set  of  homologous  points  or  features  that  could 
be  defined  consistently  among  all  taxa  at  all  times.  This  is  difficult  for  the  cranidium,  since  the  suture 
is  a continuous  feature  with  few  discrete  landmarks.  (Of  course,  the  cranidial  midline  or  axis  itself 
is  an  homologous  feature,  but  it  alone  enables  little  morphologic  description.)  Considering  other 
parts  of  the  trilobite,  homologous  points  may  be  identified  within  certain  groups,  for  example  fringe 
pits  in  trinucleids  (Hughes  1970)  and  tubercles  in  encrinurids  (Temple  and  Tripp  1979).  However, 
such  features  cannot  be  meaningfully  recognized  on  all  trilobites. 

Given  this  limitation,  it  is  necessary  to  consider  shape  per  se.  This  has  previously  been  done  by 
considering  sets  of  linear  measures  (e.g.  Ashton  and  Rowell  1975;  Rowell  et  al.  1982),  but  the  utility 
of  this  approach  generally  depends  on  restricting  the  analysis  to  a relatively  small  group  of 
trilobites.  In  this  study,  shape  was  quantified  by  a Fourier  description  of  the  closed  curve  that 
represents  the  projected  outline  of  the  cranidium.  (This  method  is  discussed  in  detail  elsewhere 
(Foote  19896),  and  only  cursory  treatment  will  be  given  here.)  The  glabella  is  an  important 
biological  feature,  since  it  reflects  cephalic  segmentation,  as  well  as  a feature  of  much  utility  in 
taxonomy.  However,  because  it  is  often  difficult  to  identify  consistently,  especially  in  many  of  the 


FOOTE:  TRILOBITE  DIVERSIFICATION 


463 


taxa  with  effaced  forms,  such  as  the  Asaphacea  and  Scutelluina,  its  morphology  was  not  considered 
in  this  study.  The  cranidium  provides  only  a limited  assessment  of  morphology,  but  it  is  necessary 
to  sacrifice  detail  for  the  sake  of  a large-scale  analysis  such  as  that  presented  here  (see  also  Raup 
1966,  1967).  For  work  at  finer  scales,  the  cranidial  outline  would  clearly  be  inadequate. 

Following  the  guidelines  of  Shaw  ( 1957,  p.  194),  the  cranidium  is  placed  in  a standard  orientation. 
The  cranidium  is  oriented  with  the  palpebral  lobe  horizontal,  or,  if  this  is  not  possible,  with  the  axial 
furrows  horizontal.  With  very  convex  forms,  the  chord  to  the  palpebral  lobe  or  axial  furrow  is  used 
to  orient  the  specimen  (Shaw  1957,  p.  194).  This  standard  orientation  allows  comparison  among 
many  diverse  forms,  and  thus  has  an  advantage  over  using  presumed  Tife  positions’,  which  vary 
from  group  to  group,  and  in  many  cases  are  not  known.  The  error  associated  with  orienting  and 
measuring  specimens  has  been  shown  to  be  small  (Foote  19896). 

The  projected  outlines  of  cranidia  were  drawn  with  a microscope  and  camera  lucida.  These 
drawings  were  digitized  electronically  and  shape  analysis  was  performed  on  the  stored  images.  As 
described  previously  (Foote  19896),  12  Fourier  coefficients  contain  approximately  99%  of  the  shape 
information  contained  in  the  cranidial  outline.  These  12  coefficients  were  used  as  morphometric 
variables,  forming  the  basis  of  a 12-dimensional  morphospace.  In  order  to  allow  equal  weighting 
of  the  variables,  the  data  were  standardized  as  x'  = (x  — x)/s,  where  x is  the  original  variate,  .v  is 
its  mean,  s is  its  standard  deviation,  and  x'  is  the  standardized  variate.  (Standardization  was  used 
rather  than  a method  such  as  the  percent-range  or  percent-maximum  transformation,  since  these 
last  two  techniques  rely  on  single,  observed  values  [minimum  and/or  maximum].  In  general,  such 
single  values  are  expected  to  be  more  heavily  influenced  by  sampling  than  statistics  of  the  entire 
population  [the  mean  and  standard  deviation],  which  are  more  reliably  determined.)  In  order  to 
allow  comparisons  among  stratigraphic  intervals,  all  data  were  standardized  at  once,  rather  than 
one  interval  at  a time. 

The  definition  of  the  outline  is  straightforward  except  when  there  are  spines.  These  spines  are  of 
two  types:  (1)  those  that  actually  form  part  of  the  cranidial  margin  (e.g.  genal  spines),  and  (2)  those 
that  are  not  part  of  the  margin  but  project  out  over  it  (e.g.  occipital  spines).  Because  spines  of  the 
first  type  actually  define  the  outline  of  the  cranidium,  these  were  included.  Spines  of  the  second  type 
were  excluded,  i.e.,  the  cranidial  outline  was  drawn  as  if  the  projecting  spine  were  not  present. 

Scope 

This  study  is  limited  to  the  Cambrian  and  Ordovician.  Although  the  Cambrian  and  Ordovician  do 
not  contain  the  major  part  of  the  total  diversity  of  most  skeletonized  marine  animals,  the  majority 
of  trilobite  abundance  and  diversity  is  concentrated  in  these  two  periods.  Thus,  the  analysis 
documents  most  of  the  evolutionary  history  of  the  trilobites. 

To  keep  the  study  tractable,  sampling  is  limited  to  North  America.  Because  the  analysis  presented 
here  is  at  a coarse  taxonomic  level  (the  evolutionary  history  of  superfamilies,  suborders  and  orders), 
biogeographic  changes  alone  would  seem  unlikely,  a priori , to  cause  the  observed  patterns.  It  is 
shown  below  that  patterns  documented  with  North  American  trilobites  are  concordant  with  those 
subjectively  determined  using  more  extensive  distributions  of  trilobites.  Therefore,  with  respect  to 
the  questions  addressed  here,  the  evolution  of  trilobites  in  North  America  is  representative  of  the 
evolution  of  the  global  trilobite  fauna.  Furthermore,  but  perhaps  less  significantly,  provinciality 
appears  not  to  change  from  the  Cambrian  to  the  Ordovician  (Valentine  et  al.  1978 ; Sepkoski  1988). 

Preservation 

Trilobites  are  frequently  sheared,  compressed,  or  crushed.  For  character  recognition,  identification, 
and  systematics,  this  may  not  present  severe  problems.  However,  morphometric  analysis  requires 
either  undistorted  material  or  material  that  is  consistently  distorted.  Consistent  distortion  is  nearly 
impossible  to  obtain,  so  one  must  use  undistorted  material.  For  this  reason,  sampling  was  limited 
almost  exclusively  to  carbonates.  Fossils  in  carbonates  are  generally  not  appreciably  distorted,  even 
though  the  rocks  themselves  may  be  compacted  (Shinn  et  al.  1977).  Some  well  preserved  cranidia 
are  used  from  non-carbonate  rocks  (e.g.  some  chert  nodules),  but  the  vast  majority  of  specimens  are 


464 


PALAEONTOLOGY,  VOLUME  34 


from  carbonates.  (This  lithologic  restriction  implies  that  the  material  represents  an  environmentally 
biased  sample.  However,  the  coarse  scale  of  the  analysis,  as  well  as  the  fact  that  the  patterns 
documented  here  are  consistent  with  other  work  involving  a broader  range  of  environments  (see 
below),  suggest  that  this  bias  is  unlikely  to  be  the  cause  of  the  observed  patterns.) 

Sampling 

Historically  there  has  been  one  group  of  systematists  that  worked  primarily  on  Cambrian  trilobites 
and  another  group  on  post-Cambrian  forms  (Whittington  1954;  Fortey,  pers.  comm.).  Thus, 
Cambrian  and  Ordovician  genus  concepts  are  unlikely  to  be  comparable,  and  sampling  simply  from 
a list  of  genera  might  impart  a bias.  One  possible  solution  to  this  problem  is  to  sample  strictly 
randomly.  This  introduces  an  unknown  amount  of  error  or  bias  reflecting  collecting  methods.  The 
magnitude  of  this  bias  should  decrease  as  the  size  of  collections  and  the  number  of  collectors 
increases.  Therefore,  material  for  this  study  was  drawn  from  large  museum  collections,  both 
stratigraphic  and  systematic  (at  the  United  States  National  Museum,  the  Museum  of  Comparative 
Zoology  (Harvard  University),  and  the  Yale  Peabody  Museum).  While  museum  collections  are  not 
strictly  random  subsets  of  all  available  fossils,  they  probably  represent  a more  random  sampling 
than  would  a list  of  genera  or  species. 

Specimens  were  chosen  randomly  from  museum  collections  by  looking  through  every  drawer 
known  to  contain  trilobites  and  selecting  every  specimen  that  was  sufficiently  well  preserved  to  allow 
morphometric  description.  The  number  of  usable  specimens  in  the  combined  collections  of  the  three 
museums  is  in  the  hundreds  to  thousands. 

Random  sampling  presents  problems  of  its  own.  Groups  of  species  tend  to  show  right-skewed 
abundance-frequency  distributions.  That  is,  there  are  many  species  with  a low  abundance  and  a few 
species  with  a high  abundance  (e.g.  Koch  1987).  It  is  therefore  likely  that  completely  random 
sampling  would  force  patterns  to  be  dominated  by  a few  abundant  species.  In  order  to  circumvent 
this  problem,  sampling  was  arbitrarily  limited  to  a maximum  of  three  specimens  per  species  per  time 
horizon  per  locality.  (To  avoid  cumbersome  working,  I will  hereafter  use  the  phrase  'per 
population’  without  implying  the  same  meaning  for  'population'  that  a neontologist  uses.)  In  this 
way,  some  degree  of  intra-populational  variability  is  quantified,  but  the  overdominance  of  very 
abundant  species  is  avoided.  (Because  data  from  many  time  planes  are  stratigraphically  lumped  to 
increase  sample  sizes  (see  below),  it  is  possible  for  more  than  three  specimens  from  a species  to  occur 
within  the  data  of  a single  stratigraphic  interval.)  Each  datum  in  this  study  represents  a single 
cranidium  selected  as  described  above.  Total  sample  size  is  560,  representing  over  250  genera  and 
over  400  species.  A list  of  genera  and  species  used  in  this  study,  and  the  Fourier  coefficients  for  all 
specimens,  were  given  by  Foote  (1989u). 

Clearly  some  taxonomic  bias  remains  with  this  method  of  sampling,  since  it  implicitly  assumes 
that  species  represent  some  real  and  consistent  unit.  If  a 'true’  species  is  finely  split  into  many 
nominal  species  then  more  sampling  is  permitted  from  this  species  than  from  a species  which  is  not 
oversplit  in  this  way.  Since  it  is  possible  (see  above)  that  Cambrian  species  are  more  finely  split  than 
Ordovician  species,  one  would  expect  the  morphologic  differences  among  related  Cambrian  species 
to  be  systematically  less  than  among  related  Ordovician  species.  However,  the  data  do  not  indicate 
this  bias.  It  is  shown  below  that  the  morphologic  difference  among  specimens  within  higher  taxa 
does  not  systematically  increase  through  time.  Thus,  although  the  analysis  cannot  be  said  to  be 
completely  free  of  taxonomic  bias,  whatever  bias  may  be  inherent  at  the  species  level  does  not 
appear  to  have  a great  effect. 

Stratigraphic  division 

The  traditional  stratigraphic  division  of  the  Cambrian  into  Lower  Cambrian,  Middle  Cambrian,  and 
Upper  Cambrian  (e.g.  Lochman-Balk  and  Wilson  1958;  Robison  1964)  is  adopted  here  (Table  1). 
A recent,  comprehensive  correlation  of  Ordovician  formations  of  the  United  States  (Ross  et  al. 
1982)  divides  the  Ordovician  into  the  Ibexian,  Whiterockian,  Mohawkian,  and  Cincinnatian  Series. 
Because  of  the  large  hiatus  in  the  Whiterockian,  sample  size  for  this  series  is  very  low.  It  would  be 


FOOTE:  TRILOB1TE  DIVERSIFICATION 


465 


table  I . Stratigraphic  division  and  sample  sizes.  Ages  and  durations  in  parentheses  based  on  Sloan  (in  press). 
Others  based  on  Sepkoski  (1979)  and  Ross  et  al.  (1982).  Ages  in  millions  of  years  before  present,  rounded  to 
nearest  million  years.  Durations  in  millions  of  years. 


Interval 

Age  at  base 

Duration 

Sample  size 

Silurian 

435 (438) 

Ordovician  3 

465 (454) 

30(16) 

73 

Ordovician  2 

485  (477) 

20  (23) 

127 

Ordovician  1 

504(504) 

19(27) 

1 16 

Upper  Cambrian 

518 (527) 

14(23) 

125 

Middle  Cambrian 

540(554) 

22  (27) 

86 

Lower  Cambrian 
(trilobite-bearing) 

562 (577) 

22 (23) 

33 

useful  to  have  a subdivision  of  the  Ordovician  that  involved  roughly  comparable  intervals  of  time 
and  comparable  sample  sizes.  I have  therefore  divided  the  Ordovician  into  three  informal  intervals, 
Ordovician  1,  Ordovician  2,  and  Ordovician  3 (Table  1).  (It  is  shown  below  that  using  the 
conventional  division  into  Ibexian,  Whiterockian,  Mohawkian,  and  Cincinnatian  Series  does  not 
alter  the  evolutionary  patterns  documented  here.)  Ordovician  1 is  defined  as  that  the  interval  from 
the  base  of  the  Ordovician  approximately  to  Ross’s  Zone  N,  near  the  middle  of  the  Whiterockian 
(c.  middle  of  the  Llanvirnian).  (The  placement  of  the  boundary  between  Ordovician  1 and 
Ordovician  2 is  somewhat  arbitrary,  since  it  lies  within  an  interval  that  is  barren  with  respect  to  data 
collected  here.  This  barren  interval  reflects  the  major  unconformity  between  the  Sauk  and 
Tippecanoe  sequences  (Sloss  1963).  All  the  trilobites  studied  are  either  clearly  from  the  lower  part 
of  the  Whiterockian  or  the  upper  part,  but  not  from  the  middle.)  The  top  of  Ordovician  2 coincides 
with  the  Blackriverian/Rocklandian  boundary  (c.  middle  of  the  Caradocian),  and  the  top  of 
Ordovician  3 coincides  with  the  Ordovician/Silurian  boundary. 

The  ages  given  in  Table  I are  not  known  with  certainty,  and  reflect  the  time  scale  given  by 
Sepkoski  (1979)  for  the  Cambrian,  and  Ross  et  al.  (1982)  for  the  Ordovician.  The  apparently  long 
duration  of  Ordovician  3 may  appear  to  present  problems,  but  it  should  be  noted  that  most  of  the 
data  for  Ordovician  3 (63  out  of  73  specimens)  are  pre-Cincinnatian  and  so  lie  within  roughly  the 
first  half  of  Ordovician  3.  An  alternative  chronology  (dates  in  parentheses  in  Table  1)  of  the 
Cambrian  and  Ordovician  (Sloan  in  press)  yields  interval  durations  that  are  rather  different  (and 
less  variable)  than  those  based  on  Sepkoski  (1979)  and  Ross  et  al.  (1982).  (For  the  dates  presented 
here,  the  Whiterockian  is  arbitrarily  divided  in  half.)  Because  this  study  does  not  use  absolute  ages 
(e.g.  to  calculate  evolutionary  rates),  the  finer  details  of  dating  are  of  minor  importance. 

Classification  of  specimens  into  suprageneric  taxa 

The  genealogies  of  trilobites  are  generally  not  sufficiently  well  known  that  all  suprageneric  taxa 
represent  natural  groupings  (e.g.  Bergstrom  1973;  Fortey  and  Chatterton  1988).  No  claim  is  made 
here  that  every  taxon  used  is  a clade.  However,  it  is  reasonable  to  assume  for  the  sake  of  discussion 
that  higher  taxa  are  rough  approximations  to  monophyletic  groups.  Eldredge  (1977,  p.  320) 
expressed  the  opinion  that  ‘many,  if  not  most’  superfamilies  as  defined  in  Harrington  ( 1959)  ‘seem 
reasonably  homogeneous’,  i.e.  ‘more  or  less  monophyletic’.  This  seems  more  reasonable  for  some 
taxa  (e.g.  Trinucleacea)  than  others  (e.g.  Ptychopariacea)  (Fortey  and  Chatterton  1988). 

For  the  purposes  of  analysing  variability  within  and  among  higher  taxa  of  trilobites,  the  level  of 
the  superfamily  is  used.  This  taxonomic  level  generally  allows  reasonably  large  sample  sizes,  and  in 
many  cases  superfamilies  appear  to  represent  morphotypes.  The  classification  used  is  primarily  that 
of  the  Treatise.  Although  this  classification  is  by  no  means  perfect,  it  is  often  presented  as  the 
closest  thing  to  a consensus  (e.g.  Clarkson  1986).  Modifications  to  the  Treatise  classification  were 
based  on  later  work  by  Fortey  and  Owens  (1975)  (Proetida),  Lane  and  Thomas  ( 1983)  (Scutelluina), 


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and  Fortey  and  Chatterton  (1988)  (Asaphina).  The  families  Lecanopygidae  and  Plethopeltidae  were 
included  in  the  Proetida.  These  forms  had  not  been  sufficiently  studied  by  Fortey  and  Owens  (1975) 
to  determine  their  affinities,  but  they  are  linked  with  other  proetids  in  the  Treatise.  Genera  named 
after  the  publication  of  the  Treatise  were  generally  classified  according  to  the  author’s  taxonomic 
assignment.  Where  suprageneric  classification  is  not  given  but  an  author  expresses  belief  in  a certain 
relationship,  that  relationship  was  used  for  suprageneric  assignment. 

In  cases  where  no  superfamilies  are  defined  (e.g.  Redlichiina),  suborders  are  treated  as  if 
consisting  of  a single  superfamily;  thus,  these  suborders  are  treated  as  taxa  of  rank  equivalent  to 
that  of  superfamilies.  Similarly,  where  no  suborders  are  defined  (e.g.  Odontopleurida),  the  order  is 
treated  as  if  consisting  of  a single  superfamily.  Of  the  560  specimens  used,  303  (541  %)  are  assigned 
to  established  superfamilies,  99  ( 1 7-7  % ) are  assigned  to  suborders  treated  here  as  superfamilies,  and 
158  (28-2%)  are  assigned  to  orders  treated  here  as  superfamilies.  Sample  sizes  for  the  higher  taxa 
range  from  1-50  and  are  given  in  Foote  (1989c/).  The  known  stratigraphic  range  for  the  higher  taxa 
correlates  well  with  the  stratigraphic  range  represented  in  this  study  (Foote  1989c/). 

The  higher  taxa  are  analysed  as  groups  irrespective  of  their  position  in  the  taxonomic  hierarchy. 
For  example,  if  the  Proetida  were  best  considered  a suborder  of  the  Ptychopariida,  or  the 
Remopleuridacea  a superfamily  within  the  Ptychopariina  rather  than  within  the  Asaphina,  this 
would  have  absolutely  no  bearing  on  the  analysis.  In  addition,  reassignment  of  specimens  to 
different  families,  genera  or  species  would  leave  the  analysis  unaffected  as  long  as  they  remained 
within  the  same  suprafamilial  taxon.  An  analysis  (not  presented  here)  using  the  suborder,  rather 
than  the  superfamily,  as  the  fundamental  higher  taxonomic  unit  yielded  results  in  agreement  with 
those  presented  here. 


DATA  ANALYSIS 

Diversification  within  the  Trilobita  as  a whole 

Before  looking  at  the  evolution  of  higher  taxa  of  trilobites,  it  is  useful  to  determine  the  patterns 
of  morphologic  diversity  for  the  trilobites  as  a whole.  Text-figure  1 shows  all  data  plotted  in  a 
two-dimensional  principal-component  space,  based  on  the  correlation  matrix  of  the  original 
12-dimensional  morphospace  of  Fourier  coefficients.  (These  two  principal  components  summarize 
approximately  63%  of  the  variability  among  specimens  contained  in  the  12-dimensional 
morphospace.)  The  principal  components  are  used  for  graphical  purposes  only;  later  calculations 
are  based  on  the  complete,  twelve-dimensional  Fourier  space.  Inspection  of  Text-figure  1 reveals  a 
clear  increase  in  morphologic  dispersion  or  variability  through  time. 

Just  a few  morphologically  extreme  specimens  could  strongly  affect  one’s  visual  impression  of  this 
pattern.  It  is  therefore  useful  to  remove  the  influence  of  extreme  specimens.  For  each  stratigraphic 
interval  the  morphologic  centroid  is  determined.  An  envelope  is  then  constructed  which  contains  the 
80%  of  the  data  lying  closest  to  the  centroid  (in  the  principal-component  space)  (Text-fig.  2).  Thus, 
the  most  extreme  20%  of  the  data  are  excluded.  Note  that  the  figure  80%  is  an  arbitrary  one,  and 
this  is  not  meant  to  be  a robust  statistical  method  for  the  removal  of  outliers.  The  point  is  to  remove 
the  effects  of  extreme  forms  without  the  assumption  or  belief  that  they  ‘don’t  belong’.  It  is  dear 
from  Text-figure  2 that  the  apparent  increase  in  overall  dispersion  is  not  the  result  of  a few  extreme 
specimens. 

That  morphologic  variability  depicted  in  this  way  tends  to  increase  is  in  agreement  with  what  one 
would  expect  from  a subjective  assessment  of  the  diversity  of  trilobite  form.  Comparing  the  diversity 
among  post-Cambrian  phacopids,  asaphids,  trinucleids,  proetids,  and  odontopleurids  to  the 
diversity  among  Cambrian  corynexochids,  redlichiids  and  ptyhoparioids,  the  picture  presented  in 
Text-figures  1 and  2 should  come  as  no  surprise.  Nevertheless,  the  quantitative  documentation  of 
this  pattern  is  important  and  useful  for  at  least  two  reasons.  First,  it  allows  a degree  of  confidence 
that  is  greater  than  that  permitted  by  a subjective  impression,  no  matter  how  keen.  Second,  it  allows 
more  detailed  evolutionary  questions  to  be  addressed,  such  as  the  taxonomic  level  at  which  the 
diversification  is  concentrated  (see  below). 


PC  2 PC  2 


FOOTE:  TRILOBITE  DIVERSIFICATION 


467 


2 - 

1 - 

0 - 
CM 

a.i- 

-2  - 

-3  - 

-4  - 
-6 


LOWER  CAMBRIAN 


N = 33 


-4 


a o 


□ rm 

□ w 


— I 

-2 

PC  1 


-6 


-2 

PCI 


text-fig.  I Trilobite  cranidia  plotted  in  principal-component  space.  Standardized  scores  for  the  first  (PC  1) 
and  second  (PC  2)  principal  components  are  shown.  Each  point  represents  a single  specimen.  Sample  sizes 

given  by  N. 


468 


PALAEONTOLOGY,  VOLUME  34 


-6  -4-2  0 2 

PC  1 


text-fig.  2.  Envelopes  surrounding  the  80%  of  the  specimens  lying  closest  to  the  centroid  for  each  respective 
stratigraphic  interval.  Axes  as  in  Text-figure  1.  Abbreviations:  LC,  Lower  Cambrian;  MC,  Middle  Cambrian; 
UC,  Upper  Cambrian;  Ol,  Ordovician  1 ; 02,  Ordovician  2;  03,  Ordovician  3. 


Even  disregarding  our  knowledge  of  the  fossil  record  of  trilobites,  such  an  increase  in  variability 
may  be  expected.  As  Stanley  (1973)  and  Gould  (1988)  have  argued,  if  a clade  or  lineage  begins  its 
history  with  a certain  morphology,  it  is  the  null  expectation  that  morphologic  variance  will  increase 
as  new  and  different  forms  evolve.  It  is  intriguing  that  morphologic  variability  continues  to  increase 
into  Ordovician  2,  even  though  generic  and  familial  diversity  are  greatest  in  the  Middle  to  Upper 
Cambrian  and  decline  through  the  Ordovician  (Sepkoski  1982,  1984,  and  unpublished  generic  data). 
Even  under  conditions  of  decreasing  taxonomic  diversity,  an  increase  in  morphologic  dispersion 
may  be  the  null  expectation  if  we  consider  morphologic  evolution  as  a ‘diffusive  process’.  The  total 
range  of  morphospace  occupied  could  tend  to  increase  even  if  the  number  of  biologic  units 
occupying  that  morphospace  decreased. 

Preliminary  analysis  of  higher  taxa 

The  morphometric  methods  established  above  allow  further  questions  to  be  addressed  concerning 
the  morphologic  evolution  of  the  trilobites.  How  does  the  gross  pattern  of  diversification  correlate 
with  patterns  among  higher  taxa?  Does  diversification  proceed  at  many  scales,  and  is  the  increase 


FOOTE:  TRILOBITE  DIVERSIFICATION 


469 


CM 

g.i 


-2 


_ ORDOVICIAN  2 

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ORDOVICIAN  3 

< < *3  **  * , 

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PC  1 PC  1 


text-fig.  3.  Scatterplots  of  the  80%  of  the  specimens  for  each  group  lying  closest  to  the  group  centroid.  Only 
groups  with  five  or  more  specimens  are  shown.  Axes  as  in  Text-figure  1.  Key:  Lower  Cambrian:  A, 
Corynexochida ; □ , Eodiscina;  Olenellina;  O.  Ptychopariacea ; Middle  Cambrian:  A,  Corynexochida ; □, 
Marjumiacea;  O,  Ptychopariacea;  0.  Solenopleuracea ; Upper  Cambrian:  B.  Anomocaracea ; i . 
Illaenuracea ; A-  Komaspidacea;  □,  Marjumiacea;  Raymondinacea ; A,  Proetida;  O.  Ptychopariacea;  0. 
Solenopleuracea;  Ordovician  1 : i , Asaphacea;  M Cheirurina;  □,  Conocoryphacea ; >K  Cyclopygacea ; A- 
Komaspidacea ; 0.  Olenacea;  A-  Proetida;  O.  Scutelluina ; Ordovician  2:  Cheirurina ; □,  Odontopleurida ; 

A.  Proetida;  Remopleuridacea ; O.  Scutelluina;  A.  Trinucleacea;  Ordovician  3:  i , Asaphacea;  other 

symbols  as  for  Ordovician  2. 


470 


PALAEONTOLOGY,  VOLUME  34 


in  dispersion  evident  within  higher  taxa  as  well?  Do  higher  taxa  represent  morphotypes,  as  was 
implicitly  assumed  above? 

The  dispersion  within  and  among  higher  taxa  is  depicted  graphically  in  Text-figure  3.  Here,  only 
the  80%  of  the  specimens  lying  closest  to  the  morphologic  centroid  (in  principal-component  space) 
for  each  group  are  presented.  As  above,  the  purpose  of  this  culling  procedure  is  to  remove  the  visual 
effect  of  extreme  specimens.  To  keep  the  graphs  simple,  only  groups  with  sample  sizes  of  at  least 
five  are  plotted.  Two  patterns  are  evident  here: 

I There  is  no  obvious  tendency  for  within-group  dispersion  to  increase  through  time.  (Note  that 
the  scatterplots  for  different  intervals  are  drawn  at  different  scales.)  At  all  times  there  are  groups 
encompassing  a large  range  of  morphology,  as  well  as  morphologically  more  restricted  taxa.  This 
is  true  even  though  some  of  the  higher  taxa  are  at  the  level  of  the  order. 

2.  The  separation  among  groups  clearly  increases  through  time.  This  pattern  is  most  striking 
when  the  Cambrian  as  a whole  is  compared  to  the  Ordovician  as  a whole,  but  the  trend  is  also 
evident  within  the  Ordovician.  Cambrian  trilobites  are  difficult  to  partition  into  suprageneric  groups 
that  correspond  to  well-defined  morphotypes,  while  at  least  some  Ordovician  taxa  correspond  to 
morphologically  well  defined  units.  This  is  in  accord  with  previous  observations  (e.g.  Rasetti  1954, 
1961;  Palmer  1958;  Whittington  1966).  It  is  likely  that  if  more  dimensions  (i.e.  morphologic 
variables)  were  added  to  this  analysis,  the  Cambrian  groups  would  become  easier  to  discriminate. 
However,  the  fact  that  discrimination  has  historically  been  relatively  difficult  suggests  that  the 
difference  between  the  Cambrian  and  the  Ordovician  is  real. 

Dispersion  within  groups  shows  no  obvious  trend,  while  dispersion  among  groups  increases.  This 
suggests  that  the  overall  morphologic  diversification  among  the  trilobites  is  tied  to  patterns  at  higher 
taxonomic  levels.  This  is  not  meant  to  imply  that  there  are  superfamily-level  evolutionary  processes 
that  differ  fundamentally  from  evolutionary  mechanisms  within  populations. 

Quantitative  analysis  of  higher  taxa 

The  patterns  depicted  in  two  dimensions  appear  striking,  but  should  be  quantified  in  the  12- 
dimensional  space.  I emphasize  that  all  subsequent  analyses  in  this  paper  are  based  on  the  complete , 
12-dimensional  Fourier  space , not  the  principal-component  space.  This  quantification  requires  the  use 
of  multivariate  measures  of  dispersion.  There  has  been  much  discussion  about  how  to  measure 
morphologic  dissimilarity  (e.g.  Van  Valen  1974;  Ashton  and  Rowell  1975;  Atchley  et  al.  1982; 
Cherry  et  al.  1982).  In  principle,  variances  (e.g.  Pearson  1926)  and  covariances  (e.g.  Atchley  et  al. 
1982)  should  be  taken  into  account  when  describing  morphologic  distances  among  groups.  In 
practice,  however,  it  has  been  found  that  simple  distance  measures  that  do  not  consider  variances 
and  covariances  are  more  reliably  estimated  (Atchley  et  al.  1982;  Cherry  et  al.  1982).  Atchley  et  al. 
(1982)  point  out  that  simple  distance  measures  may  be  more  precise  (i.e.  more  reliably  estimated) 
but  may  be  further  from  the  morphologic  ‘truth’.  For  purposes  of  this  study,  it  is  more  important 
that  distance  measures  be  reliable  so  that  they  can  be  compared  among  taxa  and  among  times. 
Therefore,  simple  Euclidean  distance  is  used  here  as  a measure  of  morphologic  dissimilarity.  If  there 
are  p variables,  then  the  Euclidean  distance  between  two  specimens  is  given  by 


d12  = 


(Xn-Xj2)* 


Lj-l 


(1) 


where  Xn  and  Xj2  are  the  values  of  variable  j on  specimens  1 and  2. 

Three  dispersion  indices  were  defined  for  the  12-dimensional  Fourier  space.  W is  the  weighted 
mean  of  all  within-group  distances,  and  gives  a measure  of  the  morphologic  variability  within  higher 
taxa.  (Methods  of  weighting  are  discussed  below.)  A is  the  weighted  mean  of  the  distances  among 
group  centroids,  and  provides  a measure  of  the  morphologic  variability  among  higher  taxa.  (The 
group  centroid  is  an  imaginary  point  representing  the  average  morphology  of  the  group,  i.e.,  the 
arithmetic  average  for  each  of  the  variables  measured  on  all  specimens  within  a group.)  Intuitively, 
it  seems  that  the  less  dispersion  there  is  within  taxa  and  the  greater  the  distance  among  taxa,  the 


FOOTE:  TRILOBITE  DIVERSIFICATION 


471 


better  defined  or  more  distinct  those  taxa  are.  Therefore,  discreteness,  D,  is  defined  as  A/W.  D is 
qualitatively  similar  to  Mahalanobis’  generalized  distance,  D 1 (Davis  1986,  p.  486).  D differs  from 
Mahalanobis’  D 2 in  that  it  does  not  take  into  account  variable  correlations  (which  may  not  be 
reliably  estimated  for  small  sample  sizes  (Atchley  et  al.  1982;  Cherry  et  al.  1982)),  and  does  not 
assume  a homogeneous  variance-covariance  structure. 

In  computing  IV,  the  number  of  pairwise  comparisons  increases  with  the  square  of  the  group 
sample  size  rather  than  with  the  sample  size  itself.  This  implies  that  large  groups  contribute 
disproportionately  to  the  average  distance.  A method  of  weighting  was  used  to  correct  for  this. 
Within-group  distances  were  weighted  so  that  each  group  contributes  to  W according  to  its  sample 
size  rather  than  the  number  of  comparisons  made  within  that  group.  This  method  of  weighting  is 
explained  below. 

If:  G is  the  number  of  groups;  ni  is  the  number  of  specimens  in  group  z (z  = 1, ; G'  is  the 
number  of  groups  with  ni  > 1 (i.e.  the  number  of  groups  in  which  comparisons  can  be  made);  c,  is 
the  number  of  pairwise  comparisons  in  group  z (equal  to  zz((zz;.  — l)/2;  N is  the  total  number 
specimens;  N'  is  the  total  number  of  specimens  in  groups  with  nt  > 1 (i.e.  the  total  number  of 
specimens  in  groups  in  which  comparisons  can  be  made);  dtjk  is  the  Euclidean  distance  between 
specimens  j and  k in  group  z;  and  d \ is  the  mean  of  all  pairwise  distances  within  group  z,  (equal  to 
dijk/cd ; then  W is  defined  as  follows: 

W=~i:dini  (2) 

1=1 


where  the  sum  is  only  over  those  groups  where  n-  > 1 . 

If  A were  computed  without  weighting,  then  a group  with  a large  sample  size,  i.e.  a group  whose 
centroid  is  very  reliably  determined,  and  a group  with  a small  sample  size,  i.e.  a group  whose 
centroid  is  less  reliably  determined,  would  make  the  same  contribution  to  the  average  distance 
among  groups  (and  therefore  to  the  determination  of  discreteness,  D).  A method  of  weighting  was 
used  so  that  each  group  contributes  to  A in  proportion  to  its  sample  size.  Thus,  groups  whose 
position  in  morphospace  is  better  determined  have  greater  weight.  This  is  explained  below. 

If:  i V,  G,  and  ni  are  defined  as  above;  z7  is  the  average  group  sample  size  (equal  to  N/G);  M is 
the  number  of  comparisons  among  groups  (equal  to  G(G—  1 )/2);  and  d(}  is  the  distance  between  the 
centroids  of  groups  i and  j ; then 


A = 


1 

2/zM 


G G 

V V 

i=l j=i+ 1 


dn{ni+nj). 


(3) 


W,  A,  and  D were  computed  for  each  of  the  six  stratigraphic  intervals.  Two  questions  were 
addressed  regarding  temporal  changes  in  dispersion  indices.  First,  does  the  Cambrian  as  a whole 
differ  from  the  Ordovician  as  a whole?  This  approach  stresses  the  transition  from  the  Cambrian  to 
the  Ordovician.  Second,  is  there  a monotonic  trend  in  the  dispersion  indices?  This  approach  stresses 
the  continuity  of  the  patterns.  Some  means  of  comparing  these  dispersion  indices  among  the 
intervals  is  needed.  This  involves  the  estimation  of  how  well  constrained  the  indices  are,  i.e.  the 
estimation  of  the  standard  error. 

Jackknifing  (Sokal  and  Rohlf  1981,  p.  795)  was  used  to  obtain  unbiased  estimates  of  W,  A,  and 
D and  to  determine  the  variability  associated  with  these  estimates.  By  this  method  one  group  is 
omitted  and  W,  A and  D are  recomputed.  (Because  W is  not  defined  for  a group  with  a sample  size 
of  one,  it  is  recomputed  only  if  the  group  omitted  has  a sample  size  greater  than  one.)  If  G,  is  the 
number  of  groups  in  the  zth  interval,  then  a pseudovalue,  Ys,  is  calculated  as  Yj  = Gi(Y)  — (Gi  — 1 ) 
(Xj),  where  A is  the  original  value  (i.e.  W,  A,  or  D),  and  X-  is  the  value  calculated  when  the  /th  group 
is  omitted.  (When  calculating  pseudovalues  corresponding  to  W,  G-  is  substituted  for  Gt.)  Each 
group  is  left  out  in  turn,  and  the  mean  of  all  the  Yj  provides  an  unbiased  estimate  of  A.  The  standard 
error  of  the  Yj  provides  an  unbiased  estimate  of  the  standard  error  of  A. 


472 


PALAEONTOLOGY,  VOLUME  34 


table  2.  Dispersion  indices  and  their  standard  errors.  In  this  and  all  subsequent  tables,  G is  the  number  of 
higher  taxa  relevant  to  the  calculation  of  A and  D,  G is  the  number  of  higher  taxa  relevant  to  the  calculation 
of  W,  and  SE  stands  for  ‘standard  error’.  Abbreviations:  LCAM,  Lower  Cambrian;  MCAM,  Middle 
Cambrian;  UCAM,  Upper  Cambrian;  ORD1,  Ordovician  1;  ORD2,  Ordovician  2;  ORD3,  Ordovician  3. 


Interval 

G 

G' 

W 

SE 

A 

SE 

D 

SE 

LCAM 

6 

4 

2-57 

0-62 

2-33 

0-72 

0-90 

0-20 

MCAM 

9 

6 

2-40 

0-50 

2-47 

0-39 

0-94 

0-39 

UCAM 

14 

10 

2-62 

018 

2-39 

0-28 

0-91 

0 12 

ORD1 

10 

10 

2-82 

0-37 

3-80 

0-41 

1 34 

0-06 

ORD2 

10 

9 

3-55 

0-76 

5-39 

116 

1 46 

0-40 

ORD3 

8 

8 

2-14 

0-26 

3-98 

0-49 

1 84 

0-22 

text-fig.  4.  Unbiased  estimates  of  within-  and  among-group  dispersion  plotted  against  stratigraphic  position. 
Error  bars  give  one  standard  error  on  either  side  of  dispersion  index.  Abbreviations  as  in  Text-figure  2. 


The  unbiased  estimates  of  W,  A , and  D are  given  with  their  standard  errors  in  Table  2 and  are 
shown  in  Text-figure  4.  A method  of  comparing  values  through  time  is  needed.  One  could  use 
parametric  statistical  approaches,  for  example,  making  multiple  comparisons  among  the  values,  or 
using  the  standard  errors  for  analysis  of  variance.  Using  the  standard  errors  estimated  with 
jackknifing  is  analogous  to  treating  each  pseudovalue  as  if  it  were  a single  observation.  Non- 
parametric  statistical  approaches  are  developed  below,  but  this  same  approach  is  used:  each 
pseudovalue  is  treated  as  a single  datum. 


FOOTE:  TRILOBITE  DIVERSIFICATION 


473 


To  test  for  differences  between  the  Cambrian  and  the  Ordovician,  the  Kruskal-Wallis  statistic, 
H (a  non-parametric  analogue  to  analysis  of  variance),  was  computed  (Sokal  and  Rohlf  1981, 
p.  430).  This  method  treats  each  observation  (pseudovalue)  as  a ranked  variate.  For  example,  there 
are  57  observations  (pseudovalues)  computed  for  the  analysis  of  d.  In  a ranking  from  lowest  to 
highest,  the  six  observations  for  the  Lower  Cambrian  have  ranks  of  30,  2,  1,  14,  47,  and  41, 
corresponding  to  the  pseudovalues  calculated  when  the  groups  Eodiscina,  Corynexochida, 
Ptychopariacea,  Solenopleuracea,  Olenellina,  and  Redlichiina,  respectively,  are  omitted.  In  the 
statistical  testing  of  H , the  distribution  of  ranks  among  categories  (i.e.  stratigraphic  intervals)  is 
compared  to  the  distribution  expected  for  a random  partitioning  of  ranks.  H is  distributed 
approximately  as  /2  for  a random  partitioning  (Sokal  and  Rohlf  1981,  p.  432). 

To  test  for  monotonic  changes  in  the  dispersion  indices,  Kendall’s  rank  correlation  coefficient,  t, 
was  computed  (Sokal  and  Rohlf  1981,  p.  602).  The  observations  are  ranked  as  above,  and  each 
stratigraphic  interval  is  ranked  from  lowest  to  highest.  Statistical  tables  were  constructed  by 
randomization.  For  example,  in  the  testing  of  A there  are  six  intervals  with  6,  9,  14,  10,  10,  and  8 
groups,  respectively.  Thus  the  total  number  of  observations  is  57.  The  ranks  1 to  57  are  randomly 
assigned  to  the  six  intervals  with  the  constraint  that  the  number  of  ranks  assigned  to  each  interval 
be  equal  to  the  actual  number  of  observations  in  that  interval,  r is  then  computed  for  the 
randomized  ranks.  This  procedure  is  repeated  1000  times  to  construct  a distribution  of  values  of  r 
that  would  be  expected  by  chance  (Table  3).  If  an  observed  value  of  r exceeds,  say,  95%  of  the 
values  obtained  by  randomization,  this  observed  value  is  considered  significant  at  p = 0-05  and  a 
monotonic  trend  is  inferred.  For  the  data  studied  here  and  for  the  culled  data  sets  discussed  below, 
distributions  of  r were  constructed  and  compared  to  the  normal  approximation  (Burr  1960;  Sokal 
and  Rohlf  1981,  p.  606;  Rohlf  and  Sokal  1981,  p.  77)  (Table  3).  Inspection  of  the  results  reveals  that 
the  distributions  constructed  by  randomization  are  generally  conservative  for  statistical  testing,  i.e., 
the  null  hypothesis  of  lack  of  monotonicity  is  less  likely  to  be  rejected. 


table  3.  Critical  values  of  r,  the  rank  correlation  coefficient,  generated  by  randomization.  ‘Tables’  refers  to 
other  tables  in  the  text  to  which  these  values  are  relevant.  ‘Indices’  refers  to  dispersion  indices  in  the  relevant 
tables  for  which  these  values  are  used.  Subscripts  for  r refer  to  the  significance  levels  generated  by 
randomization,  /’-values  give  the  corresponding  significance  level  obtained  using  the  normal  approximation. 


Tables 

Indices 

Th>5 

P 

him 

P 

^0  001 

P 

4 

W 

0-215 

0-033 

0-272 

0-0072 

0-347 

00006 

4,  11 

A , D 

0190 

0-037 

0-247 

0-0068 

0-285 

000014 

9 

W,  A,  D 

0-397 

0-021 

0-506 

00034 

0-599 

0-0006 

1 1 

W 

0-235 

0038 

0-286 

0-0062 

0-323 

0002 

As  would  be  expected  from  the  two-dimensional  representations  of  higher  taxa  (Text-fig.  3),  there 
is  no  significant  change  in  within-group  dispersion  through  time  (Table  4).  This  result  holds  whether 
the  Cambrian  as  a whole  is  compared  to  the  Ordovician  as  a whole,  or  whether  all  six  intervals  are 
compared  sequentially  for  monotonic  changes.  Thus,  the  obvious  increase  in  total  morphological 
dispersion  among  all  trilobites  does  not  result  from  the  increase  in  the  diversity  of  forms  within  an 
existing  suprageneric  taxon. 

Also  in  agreement  with  the  view  presented  in  Text-figure  3,  there  is  a significant  increase  in 
among-group  dispersion  (Table  4).  The  Cambrian  as  a whole  differs  from  the  Ordovician  as  a 
whole,  and  the  changes  among  the  six  intervals  indicate  a monotonic  trend.  The  total  increase  in 
dispersion  among  all  trilobites  is  therefore  linked  to  evolutionary  patterns  at  taxonomic  levels  above 
that  of  the  genus.  This  increase  in  among-group  dispersion  may  result  from  either  (1)  the  first 
appearance  of  new  higher  taxa  that  are  morphologically  well  removed  from  their  ancestors,  or  (2) 
the  morphological  divergence  of  established  higher  taxa,  or  some  combination  of  these  two.  These 


474 


PALAEONTOLOGY,  VOLUME  34 


table  4.  Kruskal  -Wallis  statistics  and  Kendall  rank  correlation  coefficients.  In  this  and  all  subsequent  tables, 
* indicates  statistically  significant  at  P < 0-05,  **  means  significant  at  P < 0 01,  and  ***  means  significant  at 
P < 0 001.  All  statistical  tests  in  this  study  are  two-sided. 


Index  H x 


W 0-600  0-029 

A 14-676***  0-325*** 

D 14191***  q-349*** 


alternatives  are  discussed  below.  Finally,  given  the  significant  increase  in  among-group  dispersion 
and  the  lack  of  pattern  in  within-group  dispersion,  the  morphologic  discreteness  of  higher  taxa 
increases  through  time  (Table  4).  This  is  in  accord  with  previous  observations  that  post-Cambrian 
trilobites  are  easier  to  classify  into  suprageneric  taxa  than  are  Cambrian  forms  (e.g.  Whittington 
1966). 

Reality  of  morphotypes 

In  addition  to  investigating  temporal  changes  in  dispersion  among  taxa,  it  is  important  to  determine 
whether,  for  a single  stratigraphic  interval,  the  taxa  have  some  reality  as  morphotypes.  One  way  to 
test  this  is  to  determine  whether  the  discreteness  value  observed  for  a single  stratigraphic  interval 
differs  significantly  from  discreteness  values  that  would  be  expected  for  a random  arrangement  of 
specimens  into  groups.  For  each  interval  there  are  G groups  with  sample  sizes  nt,  i = 1,...,G. 
Groups  were  artificially  constructed  so  that  the  specimens  were  randomly  divided  among  the  G 
groups  with  the  corresponding  sample  sizes.  The  discreteness,  D , was  then  calculated  for  this 
random  arrangement.  One  hundred  unique  randomizations  were  constructed  for  each  stratigraphic 
interval,  yielding  a distribution  of  values  of  D that  would  be  expected  by  chance.  Comparison 
between  observed  values  of  D and  the  distributions  of  randomized  values  for  each  interval  indicates 
that,  with  the  possible  exception  of  the  Lower  Cambrian,  the  arrangement  of  specimens  into  higher 
taxa  is  morphologically  non-random  (Table  5).  Higher  taxa  of  trilobites  are  thus  shown  to  represent 
morphotypes,  at  least  with  respect  to  the  shape  of  the  cranidium. 


table  5.  Number  of  randomized  discreteness  values  greater  than  observed.  Based  on  100  randomizations. 


Interval  N 


Lower  Cambrian 

6 

Middle  Cambrian 

0 

Upper  Cambrian 

0 

Ordovician  1 

0 

Ordovician  2 

0 

Ordovician  3 

0 

Analysis  of  persistent  taxa 

To  determine  whether  new  higher  taxa  are  morphologically  displaced  from  their  ancestors,  or 
established  higher  taxa  move  away  from  each  other  in  morphospace,  all  higher  taxa  that  appear  in 
but  a single  interval  were  first  removed  from  the  data  set,  leaving  all  taxa  that  persist  for  two  or  more 
intervals.  These  remaining  taxa  were  then  arranged  into  sets  of  coexisting,  persistent  taxa  to  form 
smaller  sets  of  data.  Five  such  data  sets  were  constructed  and  analysed  as  above  (Tables  6-10).  The 
rank  correlation  coefficient  was  computed  only  if  the  number  of  stratigraphic  intervals  was  greater 
than  two. 


FOOTE:  TRILOBITE  DIVERSIFICATION 


475 


table  6.  Dispersion  indices  for  Eodiscina,  Corynexochida,  Ptychopariacea  and  Solenopleuracea  in  Lower 
Cambrian  and  Middle  Cambrian. 


Lower  Cambrian 

Middle  Cambrian 

H 

G 

4 

4 

G' 

3 

4 

W (SE) 

2-06  (0-28) 

2-48  (0-55) 

0-50 

A (SE) 

1-42  (0-62) 

212  (0-66) 

0-33 

D (SE) 

0-66  (0-34) 

0-88  (0-32) 

0-08 

table  7.  Dispersion  indices  for  Asaphiscacea,  Crepicephalacea,  Marjumiacea,  Norwoodiacea,  Ptychopariacea 

and  Solenopleuracea  in  Middle  Cambrian  and  CIpper 

Cambrian. 

Middle  Cambrian 

Upper  Cambrian 

H 

G 

6 

6 

G' 

4 

5 

W (SE) 

1-89  (0  06) 

2-62  (0-25) 

4-86* 

A (SE) 

2-21  (0-59) 

1 98  (0-41 ) 

0-41 

D (SE) 

0-79  (0-36) 

0-76(0-17) 

2-56 

table  8.  Dispersion  indices  for  Proetida,  Komaspidacea,  and  Olenacea  in  Upper  Cambrian  and  Ordovician  1 . 

Upper  Cambrian 

Ordovician  1 

H 

G 

3 

3 

G' 

2 

3 

W (SE) 

2-88  (0-39) 

2-81  (0-52) 

0-33 

A (SE) 

1-72  (0-08) 

4-48  (1-56) 

3-86* 

D (SE) 

0-56  (0  14) 

1-75  (0-48) 

3-86* 

table  9.  Dispersion  indices  for  Scutelluina,  Cheirurina,  Proetida,  Asaphacea,  Remopleuridacea  and 
Trinucleacea  in  Ordovician  1,  Ordovician  2,  and  Ordovician  3.  G'  is  equal  to  G for  all  intervals.  H measures 
the  overall  heterogeneity  among  the  three  intervals. 

ORD1 

ORD2 

ORD3 

H r 

G 6 

6 

6 

W (SE)  2-90(0-63) 

3-57  (M3) 

2-30  (0-32) 

1-91  -0-27 

A (SE)  3-90  (0  64) 

4-81  (MO) 

4-46  (0-51) 

0-22  0-21 

D (SE)  1-33(011) 

1 26  (0-28) 

1 92  (0-24) 

3-94  0-428* 

table  10.  Dispersion  indices 

for  Scutelluina,  Odontopleurida,  Cheirurina,  Proetida,  Asaphacea,  Remo- 

pleuridacea  and  Trinucleacea 

in  Ordovician  2 and  Ordovician  3.  G'  is  equal  to  G for  both  intervals. 

Ordovician  2 

Ordovician  3 

H 

G 

7 

7 

W (SE) 

3-48  (0-81) 

2-30  (0-26) 

1-80 

A (SE) 

4-38  (1-07) 

4-13  (0-54) 

0-20 

D (SE) 

1-25  (0-15) 

1-78  (0-24) 

2-55 

476 


PALAEONTOLOGY,  VOLUME  34 


If  established  higher  taxa  diverged  morphologically,  one  would  expect  an  increase  in  among- 
group  dispersion  within  the  subsets  of  persistent  taxa.  This  is  generally  not  the  case.  The  only 
exception  is  the  transition  from  the  Upper  Cambrian  to  Ordovician  1.  Here  a significant  increase 
in  among-group  dispersion  is  marked  by  changes  in  taxonomic  composition  within  the  higher  taxa. 
Komaspidacea  in  the  Upper  Cambrian  is  dominated  by  the  Elviniidae,  and  in  the  Lower  Ordovician 
by  the  Komaspididae.  Perhaps  more  importantly,  the  Upper  Cambrian  Proetida  are  dominated  by 
plethopeltids,  and  the  Lower  Ordovician  Proetida  by  hystricurids.  That  higher  taxa  tend  to  occupy 
a relatively  fixed  place  in  morphospace  is  also  evident  from  inspection  of  Text-figure  3. 

Discussion 

Since  persistent  higher  taxa  do  not  diverge  appreciably,  the  significant  increase  in  among-group 
dispersion  is  tied  to  the  origin  of  new  higher  taxa.  This  might  be  seen  as  an  inevitable  consequence 
of  the  practice  of  classification.  When  forms  show  significant  morphological  divergence,  they  are 
perforce  assigned  to  new  higher  taxa,  leaving  a paraphyletic  residue.  The  phylogenetic  relationships 
among  higher  taxa  of  trilobites  are  not  sufficiently  well  known  to  state  with  certainty  which  groups 
are  paraphyletic.  However,  the  following  discussion  of  higher  taxa  used  in  this  study  suggests  that, 
at  the  least,  we  can  be  confident  that  paraphyly  is  more  prevalent  among  Cambrian  taxa  than 
among  post-Cambrian  taxa. 

Either  Redlichiina  or  Olenellina  would  appear  to  be  paraphyletic.  If  opisthoparian  sutures  are 
primitive,  then  Redlichiina  may  be  seen  as  the  paraphyletic  ancestor  of  Olenellina  (Eldredge  1977). 
If,  on  the  other  hand,  lack  of  dorsal  sutures  is  the  primitive  condition,  then  Olenellina  may  be  the 
paraphyletic  ancestor  of  Redlichiina  (Eortey  and  Whittington  1989).  Eodiscoids  are  probably 
derived  relative  to  polymeroid  trilobites,  and  primitive  relative  to  agnostoids  (Eldredge  1977; 
Fortey  and  Whittington  1989).  This  suggests  that  Eodiscina  is  the  paraphyletic  ancestor  to 
holophyletic  Agnostina.  Lane  and  Thomas  (1983),  in  expressing  their  belief  in  the  relationship 
between  Corynexochida  and  Scutelluina,  left  open  the  question  of  whether  the  corynexochids  are 
a paraphyletic  ancestor  of  Scutelluina,  or  a holophyletic  sister  group. 

Paraphyly  appears  to  be  quite  common  among  the  ptychoparioid  superfamilies.  Robison  (1987, 
p.  231)  believes  that  ‘many  or  most  families  [of  trilobites]  arose  independently  from  an  unspecialized 
stock  (ptychoparian) ...’  As  Eldredge  (1977)  points  out,  most  similarities  among  trilobite  groups 
represent  symplesiomorphies,  and  many  of  the  diagnoses  of  ptychoparioid  superfamilies  in  the 
Treatise  (Harrington  et  al.  1959)  read  like  descriptions  of  a generalized  trilobite.  Of  the 
superfamilies  considered  here,  Asaphiscacea,  Crepicephalacea,  Komaspidacea,  Leiostegiacea, 
Marjumiacea,  Ptychopariacea,  and  Solenopleuracea  seem  to  fit  the  description  of  a generalized 
ptychoparioid  trilobite.  On  the  other  hand,  a few  ptychoparioid  superfamilies  are  characterized  by 
features  that  may  be  seen  as  valid  synapomorphies.  Conocoryphaceans  lack  eyes,  norwoodiaceans 
are  characterized  by  proparian  or  gonatoparian  sutures,  olenaceans  have  free  cheeks  that  are  fused 
or  separated  by  a median  suture,  and  raymondinaceans  are  characterized  by  cedariiform  sutures 
(Harrington  et  al.  1959). 

Phylogenetic  analysis  of  the  Asaphina  (Fortey  and  Chatterton  1988)  suggests  that  paraphyly  is 
much  less  common  in  this  predominantly  post-Cambrian  suborder.  While  Fortey  and  Chatterton 
believe  the  Asaphacea  and  Anomocaracea  to  be  paraphyletic,  Cyclopygacea,  Dikelocephalacea, 
Remopleuridacea,  and  Trinucleaca  appear  to  be  holophyletic  (Fortey  and  Chatterton  1988). 
Although  not  supported  completely  by  formal  phylogenetic  analysis,  it  would  seem  that  other  post- 
Cambrian  taxa  are  quite  homogeneous  and  well  derived,  so  that  they  are  likely  to  be  holophyletic. 
These  include  Harpina,  Lichida,  Odontopleurida,  Phacopina,  Proetida,  and  Scutelluina. 

While  the  greater  prevalence  of  paraphyletic  taxa  in  the  Cambrian  no  doubt  contributes  to 
patterns  of  within-  and  among-group  dispersion,  one  observation  suggests  that  this  bias  is  not  alone 
responsible.  If  taxonomic  practice  forced  among-group  dispersion  to  increase  in  the  way  outlined 
above,  it  could  be  argued  that  the  increase  should  be  rather  regular.  Instead,  there  is  a large  jump 
from  the  Upper  Cambrian  to  Ordovician  1 , and  even  within  the  Ordovician  the  increase  can  be  seen. 
But  within  the  Cambrian  there  is  virtually  no  change  in  among-group  dispersion.  There  is 


FOOTE:  TRILOBITE  DIVERSIFICATION 


477 


something  about  the  distribution  of  forms  in  the  Ordovician  that  allows  systematists  to  define 
groups  in  such  a way  that  newer  groups  are  morphologically  far  removed  and  distinct  relative  to 
older  taxa.  If  the  separation  of  younger  taxa  were  merely  the  result  of  this  taxonomic  artifact,  then 
one  would  expect  to  see  the  pattern  within  the  Cambrian,  if  the  distribution  of  Cambrian  forms 
allowed  this  taxonomic  practice  to  be  exercised. 

Taxonomic  artifact  of  another  sort  must  also  be  considered.  As  discussed  above  and  elsewhere 
(e.g.  Whittington  1954;  Foote  1988),  it  is  possible  that  Cambrian  and  post-Cambrian  genus 
concepts  are  not  wholly  compatible.  The  sampling  methods  employed  here  were  designed  to 
circumvent  this  bias.  However,  if  taxonomic  concepts  were  disparate  at  higher  levels  as  well,  this 
difference  could,  in  part,  cause  the  patterns  seen  here.  The  results  shown  above  could  conceivably 
tell  more  about  changes  in  taxonomic  practice  than  in  the  occupation  of  morphospace.  However, 
changes  in  taxonomic  practice  are  not  independent  of  changes  in  the  distribution  of  forms.  It  seems 
reasonable  to  suppose  that  if  genera  in  the  Cambrian  showed  a distribution  of  forms  that  would 
allow  them  to  be  arranged  into  discrete  suprageneric  taxa,  then  they  would  have  been.  Simply  put, 
the  results  of  this  quantitative  analysis  are  in  agreement  with  what  students  of  trilobites  have  long 
known  regarding  the  distinctness  of  higher  taxa  (e.g.  Rasetti  1954,  1961 ; Whittington  1954,  1966; 
Palmer  1958). 

The  pattern  of  increasing  taxonomic  separation  is  clearly  linked  to  the  overall  morphological 
diversification  of  the  trilobites.  It  is  conceivable  that  Cambrian  forms  are  difficult  to  arrange  into 
discrete  suprageneric  groups  because  the  total  amount  of  morphospace  occupied  is  so  small.  It  is 
also  possible  that  taxonomic  separation  is  high  in  the  Ordovician  because  of  the  influence  of  a few 
extreme  groups.  Ordovician  taxa  in  the  inner  regions  of  morphospace  might  be  similar  in 
distinctness  to  Cambrian  taxa.  If  so,  the  increase  in  average  separation  could  be  caused  by  the  large 
among-group  distances  associated  with  the  morphologically  peripheral  taxa.  However,  the  observed 
pattern  is  not  the  result  of  these  two  factors,  as  shown  by  the  following  analysis. 

The  morphologic  centroid  (in  the  complete,  12-dimensional  space)  was  calculated  for  each 
stratigraphic  interval.  A morphologic  distance  was  chosen  that  defines  a hypersphere  centred  on  the 
Middle  Cambrian  centroid,  and  within  which  90%  of  the  Middle  Cambrian  data  happen  to  fall. 
(This  choice  is  somewhat  arbitrary,  but  is  justifiable.  A much  smaller  volume  would  exclude  too 
much  of  the  Ordovician  data.  For  example,  the  volume  containing  80%  of  the  Middle  Cambrian 
data  includes  only  14%  of  the  data  of  Ordovician  2,  and  therefore  makes  statistical  analysis 
dubious.  On  the  other  hand,  a much  larger  volume  would  include  too  much  data,  and  therefore 
make  the  analysis  nearly  identical  with  that  presented  above.)  The  same  volume  is  placed  in  turn 
in  each  of  the  six  stratigraphic  intervals,  centred  on  the  morphologic  centroid  for  that  interval.  This 
constant  volume  contains  79%  of  the  Lower  Cambrian  data,  90%  for  the  Middle  Cambrian,  77% 
for  the  Upper  Cambrian,  59%  for  Ordovician  1,  44%  for  Ordovician  2,  and  58%  for  Ordovician 
3. 

Analyses  of  the  data  within  the  constant  volume  indicates  the  same  pattern  as  the  unculled  data. 
There  is  no  significant  change  in  within-group  dispersion,  but  among-group  dispersion  and 
discreteness  increase  significantly.  This  implies  that  the  pattern  is  not  caused  by  extreme  taxa,  and 
can  be  detected  at  a smaller  scale.  With  respect  to  taxonomic  practice,  we  can  conclude  that 
Cambrian  forms  are  difficult  to  classify  into  discrete  higher  taxa  not  because  the  total  amount  of 
morphospace  occupied  is  smaller,  but  because  the  Ordovician  morphospace  is  occupied  in  a more 
discontinuous  manner. 

BIASES  IN  DATA  COLLECTION  AND  STRATIGRAPHIC  CLASSIFICATION 

Several  analyses  are  presented  below  to  correct  for  various  potential  biases  in  data  collection  and 
stratigraphic  classification.  These  analyses  involve  subsets  of  data  that  are  culled  from  the  original 
data  set.  Space  limitations  preclude  detailed  presentation  of  results,  but  all  further  analyses  yield 
patterns  in  general  agreement  with  those  presented  above.  More  detailed  treatment  can  be  found 
in  Foote  ( 1 989<ar). 


478 


PALAEONTOLOGY,  VOLUME  34 


General  statement  regarding  data  standardization 

As  explained  above,  all  data  were  standardized  to  allow  for  equal  weighting  of  the  variables. 
Because  the  standardized  variates  depend  on  the  calculated  mean  and  standard  deviation  of  the 
original  variates,  they  will  differ  somewhat  depending  on  whether  the  data  are  standardized  before 
or  after  culling.  The  following  general  guideline  is  used  to  decide  when  to  perform  the 
standardization.  If  the  purpose  of  culling  is  to  correct  for  a bias  that  is  expected  to  'distort'  the 
morphospace,  then  standardization  is  done  after  culling.  (For  example,  oversampling  of  a particular 
group  or  time  period  would  bias  the  mean  and  standard  deviation,  so  standardization  would  be 
done  after  the  oversampled  data  were  removed.)  Otherwise,  data  would  be  standardized  before 
culling. 

Differences  in  sample  size 

It  is  conceivable  that  changes  in  sample  size  could  contribute  to  the  pattern  in  group  separation.  For 
example,  an  increase  in  sample  size  would  increase  the  chance  of  sampling  morphologically  extreme 
forms,  and  this  could  tend  to  increase  the  apparent  dispersion  among  groups.  This  seems  unlikely 
a priori.  The  Upper  Cambrian,  Ordovician  1,  and  Ordovician  2 have  roughly  the  same  sample  sizes, 
but  the  pattern  of  increasing  among-group  dispersion  is  still  evident  if  these  intervals  are  compared 
(Table  2).  Nevertheless,  the  effects  of  this  potential  bias  should  be  treated  explicitly. 

To  do  so,  the  data  were  culled  in  two  ways:  (1)  The  Lower  Cambrian  was  omitted  because  of  its 
very  small  sample  size,  and  from  each  of  the  remaining  five  intervals  73  specimens  (corresponding 
to  the  smallest  of  the  sample  sizes,  that  for  Ordovician  3)  were  chosen  at  random.  (2)  The  Lower 
Cambrian  was  retained,  and  33  specimens  (corresponding  to  the  Lower  Cambrian  sample  size)  were 
randomly  chosen  from  each  interval.  In  both  cases  the  data  were  standardized  after  culling  and  were 
subjected  to  the  same  analysis  outlined  above.  The  results  of  this  analysis  are  in  agreement  with 
those  presented  above,  indicating  that  differences  in  sample  size  are  not  the  cause  of  the  observed 
patterns. 

Sampling  procedure 

Perhaps  more  significant  than  sample  size  itself  is  the  way  in  which  specimens  were  chosen.  The 
sampling  procedure  described  above  allowed  up  to  three  specimens  per  population  to  be  sampled. 
Systematic  changes  in  abundance  could  bias  the  pattern  of  within-group  variability.  There  are  more 
species  in  the  Ordovician  that  are  represented  well  enough  in  museum  collections  to  reach  this 
‘saturation  point’  of  three  specimens  per  population.  This  partly  reflects  the  diverse  silicified  faunas 
from  the  Ibexian  of  Utah  (Ross  1951)  and  the  Whiterockian  and  Mohawkian  of  Virginia 
(Whittington  1941,  1956,  1959;  Whittington  and  Evitt  1953).  In  general,  replicates  of  the  same 
species  reduce  the  amount  of  within-group  dispersion,  since  replication  results  in  more  within- 
species  comparisons,  i.e.  more  small  distances.  If  this  bias  were  strong  enough  it  would  artificially 

table  1 1.  Dispersion  indices  for  data  set  allowing  maximum  of  one  specimen  per  population.  Abbreviations 
for  stratigraphic  intervals  as  in  Table  2. 


G 

G' 

W (SE) 

A (SE) 

D (SE) 

LCAM 

6 

4 

3-01  (0-72) 

2-42  (0-75) 

0-80  (0-17) 

MCAM 

9 

6 

2-42  (0-51) 

2-48  (0-41) 

0-94  (0-36) 

UCAM 

14 

10 

2-69  (019) 

2-37  (0-27) 

0-88  (0  11) 

ORD1 

10 

9 

3-06  (0-42) 

3-87  (0-45) 

1-26  (0-08) 

ORD2 

10 

8 

3-81  (0-82) 

5-68  (T2) 

1-42  (0-43) 

ORD3 

8 

7 

2-27  (0-31) 

4 12  (0  51) 

1-79  (0-26) 

H 

0-98 

17-49*** 

j 1 

T 

0051 

0-352** 

0-353** 

FOOTE:  TRILOBITE  DIVERSIFICATION 


479 


increase  the  apparent  discreteness  of  the  Ordovician  groups.  To  eliminate  this  bias  the  data  were 
culled  so  that  a maximum  of  a single  specimen  per  population  was  retained.  The  data  were 
standardized  after  culling,  and  analysed  as  above. 

As  would  be  expected,  within-group  dispersion  for  all  stratigraphic  intervals  is  higher  when  the 
replicates  are  removed  (Table  1 1).  Although  this  effect  appears  to  be  greater  in  the  Ordovician,  it 
does  not  significantly  alter  the  patterns  observed.  Of  course,  this  does  not  address  the  issue  of  what 
would  have  happened  had  a different  limit  been  imposed,  say  six  replicates  rather  than  three.  But 
the  small  difference  between  one  and  three  replicates  suggests  that  the  effect  would  probably  have 
been  small.  It  is  likely  that  unlimited  (i.e.  completely  random)  sampling  would  have  a greater  effect, 
but  such  a method  of  sampling  is  difficult  to  justify,  as  explained  above. 

Extreme  data 

There  are  two  types  of  extreme  data  that  could  potentially  affect  the  evolutionary  patterns 
observed:  (1)  specimens  that  are  extreme  relative  to  the  majority  of  specimens  within  a stratigraphic 
interval,  and  (2)  specimens  within  a group  that  lie  at  the  morphological  periphery  of  that  group.  A 
few  extreme  data  of  the  first  kind  in  the  Ordovician  could  conceivably  cause  the  observed  increase 
in  among-group  distance,  but  this  appears  not  to  be  the  case  here.  This  potential  bias  was  implicitly 
tested  above  when  the  data  were  culled  to  exclude  all  specimens  lying  outside  a certain  constant 
volume  in  morphospace.  The  same  patterns  are  seen  near  the  centre  of  morphospace  as  throughout 
the  entire  morphospace. 

Extreme  specimens  within  a group  may  increase  mean  within-group  distance.  To  determine 
whether  such  specimens  have  a strong  effect,  the  data  were  culled  as  follows.  The  morphological 
centroids  were  determined  for  each  group.  The  80%  of  the  specimens  in  each  group  falling  closest 
to  the  group  centroid  were  retained,  and  the  remaining  20%  of  the  data  discarded.  This  procedure 
is  not  intended  to  define  outliers  statistically  but  rather  to  determine  the  effects  of  the 
morphologically  least  ordinary  specimens  within  a group.  It  is  not  claimed  that  the  specimens 
defined  in  this  way  as  "extreme’  do  not  ‘belong’  in  the  data  set,  i.e.,  there  is  no  ‘distortion’  of 
morphospace  by  these  specimens.  Therefore,  the  data  were  standardized  before  culling.  The  results 
indicate  that  none  of  the  dispersion  indices  change  as  a result  of  culling  in  such  a way  as  to  alter 
the  basic  evolutionary  pattern. 

Small  groups 

There  are  several  higher  taxa  that  at  certain  times  are  represented  by  only  a few  specimens. 
Dispersion  statistics  for  smaller  groups  are  generally  less  reliable  (Atchley  et  at.  1982).  One  way  that 
small  sample  size  is  accounted  for  here  is  by  using  dispersion  indices  that  do  not  rely  on  the 
estimation  of  the  covariance  structure  of  the  variables.  In  addition,  small  groups  are  given  less 
weight  in  the  calculation  of  dispersion  indices.  Finally,  as  the  analyses  of  culled  data  presented 
above  indicate,  the  patterns  observed  are  relatively  robust  in  the  face  of  changes  in  sample  size. 
Nevertheless,  it  is  worth  testing  explicitly  for  the  effects  that  small  group  sizes  might  have  on  the 
determination  of  within-  and  among-group  measures  of  dispersion. 

To  do  so,  the  data  were  culled  to  remove  all  groups  with  less  than  an  arbitrary  minimum  of  five 
specimens.  Because  this  culling  procedure  is  intended  to  test  whether  small  groups  represent  an 
unbiased  subset  of  all  groups  rather  than  whether  small  groups  ‘distort’  morphospace,  the  data 
were  standardized  before  culling.  Within-  and  among-group  dispersion  indices  for  the  culled  data 
are  very  similar  to  those  for  the  unculled  data.  Furthermore,  the  pattern  of  secular  changes  in  the 
dispersion  indices  is  unaltered,  suggesting  that  small  groups  do  not  bias  the  results.  There  is  nothing 
intrinsically  different  about  small  groups  relative  to  large  groups  with  respect  to  morphologic 
dispersion. 

Stratigraphic  division  of  the  Ordovician 

Different  aspects  of  sampling  strategy  and  sample  size  appear  to  have  but  minor  effects  on  the 
dispersion  indices  calculated  here.  It  is  possible,  however,  that  the  way  in  which  the  data  are  lumped 


480 


PALAEONTOLOGY,  VOLUME  34 


has  some  influence.  To  test  for  this,  an  alternative  method  for  subdividing  the  Ordovician  was  used, 
namely,  the  four-fold  North  American  standard  of  Ibexian,  Whiterockian,  Mohawkian,  and 
Cincinnatian  series  (Ross  et  al.  1982).  Both  the  unculled  data  and  the  data  culled  to  correct  for 
sample  size  yield  results  in  agreement  with  those  obtained  using  the  three-fold  division  of  the 
Ordovician. 


DISCUSSION 

The  analyses  presented  above  indicate  that  the  observed  patterns  of  within-  and  among-group 
dispersion  are  unlikely  to  result  from  biases  inherent  in  the  methods  of  data  collection  and  analysis. 
It  should  be  noted  that  the  different  data  sets  that  are  analysed  are  not  independent.  Thus,  the 
various  results  do  not  provide  independent  verification  of  the  patterns. 

How  a morphospace  is  defined  is  one  determinant  of  the  patterns  detected  in  that  morphospace. 
This  study  has  drawn  conclusions  about  trilobite  evolution  based  on  the  evolution  of  the  trilobite 
cranidium.  It  might  reasonably  be  asked  what  patterns  would  have  emerged  if  a different  aspect  of 
trilobite  form  had  been  considered.  Two  facts  suggest  that  the  patterns  would  have  been  concordant 
with  those  documented  here.  First,  the  result  that  higher  taxa  in  the  Ordovician  are  more  distinct 
than  those  in  the  Cambrian  is  in  agreement  with  previous  observations  based  on  gross  morphology 
(e.g.  Whittington  1954,  1966).  Many  aspects  of  trilobite  morphology  have  contributed  to  their 
classification  (Harrington  1959).  That  patterns  based  on  the  cranidium  agree  with  the  general 
impressions  of  trilobite  workers  serves  as  an  a posteriori  justification  for  the  choice  of  the  cranidium 
in  defining  the  trilobite  morphospace.  Second,  Whittington  (1988a,  19886)  has  found  that  the 
hypostomes  of  post-Cambrian  trilobites  map  well  onto  suprageneric  groups,  while  Cambrian  taxa 
are  more  difficult  to  characterize  by  their  hypostomes.  This  provides  independent  documentation 
of  the  same  pattern  shown  in  this  study,  but  with  a completely  different  morphological  system. 

Interpretations  of  the  results  of  this  study  are  reliable  only  insofar  as  the  taxa  employed  have 
biological  reality.  The  classification  of  trilobites  is  certainly  not  at  its  acme.  Future  changes  in 
classification  will  clearly  affect  the  fine  details  and  perhaps  even  the  major  features  of  the  patterns 
presented.  This  study  is  not  intended  as  the  last  word  on  the  evolution  of  higher  taxa  of  trilobites. 
But  the  approaches  presented  here  are  valid  for  the  investigation  of  patterns  in  the  occupation  of 
trilobite  morphospace. 

Two  potential  biases  in  the  analysis  need  to  be  considered,  but  cannot  be  dealt  with  by  simple 
culling  of  the  data.  These  are  (1)  variation  in  the  duration  of  stratigraphic  intervals,  and  (2) 
inaccuracies  and  inconsistencies  in  the  definition  of  higher  taxa. 

Because  of  time-averaging,  a greater  variety  of  form  is  likely  to  be  lumped  within  a stratigraphic 
interval  in  proportion  to  the  amount  of  time  represented  by  that  interval.  As  more  time  is  lumped 
into  a single  interval,  the  distinctness  of  higher  taxa  should  decrease  as  time-averaging  causes  them 
to  be  represented  by  a more  variable  array  of  forms.  Thus,  a systematic  decrease  in  the  duration  of 
intervals  higher  in  the  stratigraphic  column  could  artificially  induce  an  increase  in  discreteness.  It 
appears,  however,  that  this  bias  is  not  at  work  here.  The  dates  for  the  boundaries  of  stratigraphic 
intervals  cannot  be  taken  too  literally,  but  neither  the  conventional  time  scale  nor  that  based  on 
Sloan's  work  suggests  a systematic  shortening  of  interval  lengths  (Table  1).  While  there  can  be  no 
doubt  that  the  duration  of  an  interval  must  affect  the  dispersion  indices,  secular  changes  in  these 
indices  are  not  the  result  of  variations  in  interval  length. 

If  there  were  changes  in  taxonomic  turnover  rates,  then  stratigraphic  lumping  could  conceivably 
cause  the  patterns.  Given  intervals  of  equal  duration,  more  variability  would  accumulate  within  a 
taxon  (because  of  time-averaging)  if  turnover  were  more  rapid.  The  rate  of  generic  turnover  in 
trilobites  decreased  from  the  Cambrian  to  the  Ordovician  (Foote  1988;  Sloan  in  press),  but 
Cambrian  taxa  apparently  did  not  accumulate  more  morphologic  variability  within  a stratigraphic 
interval.  Within-group  dispersion  in  the  Cambrian  is  not  significantly  higher  than  in  the  Ordovician. 

If  there  were  inconsistencies  in  the  concepts  of  higher  taxa  such  as  superfamilies,  then  these  could 
conceivably  bias  the  results  of  any  analysis  that  relied  on  higher  taxa  as  defined.  It  is  argued  above 
and  elsewhere  (e.g.  Whittington  1954)  that  the  apparent  differences  between  Cambrian  and 


FOOTE:  TRILOBITE  DIVERSIFICATION 


481 


Ordovician  taxa  are  unlikely  to  arise  from  different  taxonomic  practice  alone.  Nevertheless,  it  would 
be  desirable  to  have  greater  compatibility  among  taxonomic  concepts.  One  approach  would  be 
progressively  to  improve  the  taxonomy  of  trilobites.  As  higher  categories  are  defined  more 
consistently,  different  taxa  at  different  times  can  be  compared  more  meaningfully.  And  as  higher 
taxa  more  closely  approximate  natural  groups,  evolutionary  interpretations  of  patterns  at  the  higher 
taxonomic  level  will  be  more  reliable.  Yet,  there  will  always  be  room  for  improvement. 
Furthermore,  the  very  existence  of  a taxonomy  imposes  structure  on  the  analysis. 

The  finding  that  trilobite  taxa  become  more  distinct  through  time  implies  that  the  gaps  in 
morphospace  become  more  pronounced,  and  the  clusters  in  morphospace  tighter.  As  discussed 
above,  each  specimen  is  represented  by  a single  point  in  morphospace.  If  the  apparent  pattern  is  not 
simply  the  result  of  taxonomic  practice,  then  changes  in  the  occupation  of  morphospace  should  be 
detected  as  changes  in  the  degree  of  clustering  of  these  points.  Several  methods  exist  in  ecology  (e.g. 
Clark  and  Evans  1954),  physical  cosmology  (Peebles  1980),  and  other  fields  to  quantify  the  intensity 
of  clustering  of  points.  Results  based  on  a modification  of  one  of  these  methods  indicate  that 
morphological  clusters  do  become  tighter  from  the  Cambrian  to  the  Ordovician.  Therefore,  the 
patterns  documented  here  are  not  solely  the  result  of  taxonomic  artifact  (Foote  1989a). 

Massive  extinctions  are  potentially  important  in  causing  the  patterns  documented  here.  It  is 
commonly  argued  that  extinctions  can  foster  subsequent  radiations  by  clearing  out  large  areas  of 
ecospace  (e.g.  Valentine  1969;  Colbert  1980,  p.  443).  While  such  radiations  proceed  by  the 
multiplication  of  species,  the  scale  and  tempo  of  radiations  into  relatively  empty  ecospace  result  in 
patterns  detected  at  higher  taxonomic  levels  (Valentine  1969).  The  largest  single  increase  in  the 
separation  among  higher  taxa  of  trilobites  occurs  in  the  transition  from  the  Upper  Cambrian  to  the 
Lower  Ordovician.  (Although  the  difference  in  among-group  dispersion.  A,  between  Ordovician  1 
and  Ordovician  2 is  numerically  slightly  larger,  the  standard  error  associated  with  A in  Ordovician 
2 is  so  large  as  to  make  this  transition  less  striking  [Table  2].)  The  Upper  Cambrian  and 
Tremadocian  both  are  well  known  as  times  of  rapid  turnover  in  the  trilobites  (e.g.  Stubblefield  I960; 
Fortey  1983;  Palmer  1984).  Because  of  the  importance  of  international  correlation,  much  attention 
has  been  paid  to  the  Cambro-Ordovician  boundary  itself  (e.g.  Bassett  and  Dean  1982).  However, 
increased  resolution  (Sepkoski  1979,  p.  223)  and  more  detailed  palaeontological  investigation  have 
shown  that  many  Cambrian  trilobite  families  endure  into  the  Ordovician  (e.g.  Fortey  1 983 ; Westrop 
and  Ludvigsen  1987).  Considering  the  coarse  scale  of  analysis  used  here,  the  exact  temporal 
distribution  of  the  extinctions  is  not  of  the  utmost  importance.  The  extinctions  were  apparently 
sufficiently  significant  to  effect  the  evacuation  of  ecospace,  and  play  a role  in  the  post-Cambrian 
radiation  of  higher  taxa  of  trilobites  (e.g.  Stubblefield  1960). 

The  analyses  presented  above  show  that  morphotypes  become  better  defined  and  morphologic 
gaps  become  more  pronounced  through  time.  Within-group  dispersion  does  not  change  significantly 
from  the  Cambrian  to  the  Ordovician.  The  latter  statement  is  somewhat  misleading,  however. 
Overall  dispersion  and  the  dispersion  among  higher  taxa  do  increase  substantially.  Therefore, 
dispersion  within  groups  decreases  as  a proportion  of  the  total  amount  of  morphospace  occupied. 
There  is  a morphologic  radiation,  but  diversification  at  lower  levels  does  not  keep  up  with 
diversification  at  higher  levels. 

Occupation  of  different  adaptive  zones  by  related  groups  of  organisms  is  often  marked  by 
morphological  differences  among  those  groups  (e.g.  Van  Valen  1971).  The  large  divergence  among 
trilobite  morphotypes  may  indicate  the  colonization  of  new  adaptive  zones.  Valentine  (1969)  saw 
the  Palaeozoic  radiation  as  taking  place  primarily  by  the  subdivision  of  niches,  while  the  Mesozoic 
and  Cenozoic  radiations  involved  the  opening  of  new  adaptive  zones.  The  data  here  appear 
consistent  with  a slightly  modified  view  of  the  Palaeozoic  radiation  (at  least  for  trilobites).  If 
morphotypes  in  some  rough  way  can  be  said  to  approximate  adaptive  zones,  then  the  morphologic 
radiation  of  trilobites  in  the  middle  and  upper  Cambrian,  as  Valentine  (1969)  said,  may  not  proceed 
by  the  opening  of  new  adaptive  zones.  But  the  Ordovician  radiation  of  new  morphotypes  may 
indicate  a change  in  the  mode  of  diversification,  involving  the  opening  of  new  adaptive  zones. 

Higher  taxa  of  trilobites  represent  discernible  morphotypes,  as  shown  by  the  non-random 


482 


PALAEONTOLOGY,  VOLUME  34 


arrangement  of  specimens  into  higher  taxa.  However,  these  morphotypes  need  not  represent 
adaptive  zones.  Raup  and  Gould  (1974)  showed  that  stochastic  simulations  of  morphologic 
evolution  result  in  clades  that  are  morphologically  distinct.  Coherent  morphotypes  are  to  be 
expected  from  genealogical  processes  and  may  say  nothing  about  adaptive  themes.  Similarly,  an 
increase  in  the  total  range  of  morphospace  occupied  may  be  a null  expectation  (Raup  and  Gould 
1974;  Gould  1988). 

How  does  the  morphologic  radiation  of  the  trilobites  compare  to  that  in  other  groups?  Campbell 
and  Marshall  (1987)  analysed  the  diversification  of  the  Echinodermata  in  terms  of  the  origination 
of  new  characters.  They  concluded  that  the  echinoderm  classes  do  not  converge  morphologically 
toward  their  origin,  but  are  distinct  at  their  earliest  occurrence.  Smith  ( 1988)  has  disputed  this  claim, 
arguing  that  it  rests  largely  on  taxonomic  practice.  Runnegar  (1987)  has  expressed  the  opinion  that 
early  molluscan  taxa  are  recognizable  only  in  hindsight  because  they  subsequently  diversified. 
Yochelson  (1979),  however,  believes  that  molluscan  classes  originated  abruptly  as  morphologically 
distinct  units.  That  dilferent  workers  reach  opposite  conclusions  working  with  the  same  material 
suggests  that  new  approaches  to  the  problem  may  be  needed.  In  contrast  to  Campbell  and 
Marshall’s  view  of  the  Echinodermata  and  Yochelson’s  view  of  the  Mollusca,  the  evidence  from 
orders  of  mammals  suggests  that  their  Cenozoic  radiation  has  largely  involved  continued 
morphological  divergence  (Simpson  1953,  p.  226;  Van  Valen  1971). 

As  Campbell  and  Marshall  (1987)  imply,  the  issue  underlying  whether  origins  are  ‘sudden’  is  not 
just  about  differences  in  rates.  It  is  also  important  whether  morphologic  divergence  continues 
throughout  the  history  of  a group,  or  is  concentrated  in  one  or  a few  episodes.  It  cannot  be  argued 
that  trilobite  taxa  are  recognizable  merely  in  hindsight,  after  they  diverge  and  diversify.  Quantitative, 
morphological  evidence  presented  here  demonstrates  that  higher  taxa  of  trilobites,  from  the  point 
in  the  stratigraphic  record  where  they  are  recognizable  as  higher  taxa,  do  not  continue  to  diverge. 
In  this  respect,  the  origin  of  higher  taxa  of  trilobites  may  justifiably  be  regarded  as  ‘sudden’. 


SUMMARY  AND  CONCLUSIONS 

1.  A Fourier  description  of  the  trilobite  cranidium  allows  the  quantitative  documentation  of 
morphologic  diversification  in  the  Cambrian  and  Ordovician. 

2.  Morphologic  variability  in  the  trilobites  as  a whole  increased  from  the  Early  Cambrian  to  the 
Middle  Ordovician,  with  a decline  in  the  Late  Ordovician. 

3.  Diversity  of  form  and  generic  diversity  do  not  correlate  strongly.  Previous  work  indicates  that 
the  latter  showed  a maximum  in  the  Middle  to  Upper  Cambrian,  while  results  presented  here  show 
that  the  former  was  highest  in  the  Middle  Ordovician. 

4.  Morphologic  dispersion  within  higher  taxa  of  trilobites  did  not  change  significantly  through 
time,  although  it  did  decrease  in  proportion  to  the  total  amount  of  morphospace  occupied.  This 
result  is  sensitive  to  the  way  higher  taxa  are  defined. 

5.  Morphologic  dispersion  among  higher  taxa  increased  significantly  from  the  Cambrian  to  the 
Ordovician,  as  did  the  morphologic  distinctness  of  higher  taxa.  This  pattern  resulted  from  the 
origination  of  new  higher  taxa,  not  the  divergence  of  established  higher  taxa.  Patterns  involving 
higher  taxa  are  sensitive  to  the  way  that  higher  taxa  are  defined,  but  are  not  caused  solely  by 
taxonomic  practice. 

6.  These  patterns  are  observed  even  in  confined  regions  in  morphospace  and  therefore  do  not 
result  solely  from  the  contribution  of  extreme  taxa. 

7.  The  patterns  do  not  result  from  any  likely  bias  in  data  collection  or  treatment. 

8.  The  cause  for  this  increase  in  morphologic  discontinuity  is  not  clear.  Possible  explanations 
include  (a)  the  expectation  of  a stochastic  process  and  ( b ) radiation  into  new  adaptive  zones.  The 
latter  process  was  facilitated  by  extinctions  in  the  Late  Cambrian  and  Early  Ordovician. 


Acknowledgements . For  guidance,  encouragement,  and  advice  I thank  D.  M.  Raup,  D.  Jablonski,  S.  M. 
Kidwell,  and  J.  J.  Sepkoski,  Jr.  For  discussions,  suggestions  and  criticisms  I thank  T.  Baumiller,  R.  Chappell, 


FOOTE:  TRILOBITE  DIVERSIFICATION 


483 


R.  Cranium,  R.  A.  Fortey,  S.  J.  Gould,  S.  Holland,  J.  Hopson,  M.  Listokm,  R.  Ludvigsen,  D.  McShea,  D. 
Miller,  M.  Morgan,  A.  R.  Palmer,  M.  Patzkowsky,  F.  Richter,  J.  W.  Valentine,  H.  B.  Whittington,  and  three 
reviewers.  For  access  to  museum  collections  I thank : F.  d’Escrivan  and  R.  Eng  at  the  Museum  of  Comparative 
Zoology;  F.  J.  Collier  and  J.  Thompson  at  the  United  States  National  Museum;  and  R.  D.  White  at  the  Yale 
Peabody  Museum.  R.  and  W.  Allmon,  S.  Arafeh,  D.  and  J.  Canty,  F.  and  K.  McGrath,  L.  Novakoski, 
R.  Ross,  K.  Smith,  and  J.  Tingle  generously  provided  lodging  during  museum  visits.  Financial  support  was 
provided  by  the  Geological  Society  of  America,  Sigma  Xi,  a National  Science  Foundation  (US)  Graduate 
Fellowship,  and  the  University  of  Chicago. 


REFERENCES 

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MIKE  FOOTE 

Committee  on  Evolutionary  Biology 
University  of  Chicago 
Chicago,  Illinois  60637,  USA 

Present  address: 

Typescript  received  18  September  1989 
Revised  typescript  received  2 April  1990 


Museum  of  Paleontology 
University  of  Michigan 
Ann  Arbor,  Michigan  48109,  USA 


THE  PALEORHINUS  BIOCHRON  AND  THE 
CORRELATION  OF  THE  NON-MARINE  UPPER 
TRIASSIC  OF  PANGAEA 

by  Adrian  p.  hunt  and  SPENCER  G.  LUCAS 


Abstract.  We  describe  a new  skull  of  the  phytosaur  Paleorhinus  bransoni  from  Palo  Duro  Canyon, 
Randall  County,  Texas.  The  genus  Paleorhinus  (synonyms,  Mesorhinus , Promystriosuchus , Francosuchus , 
Ebrachosuchus,  Mesorhinosuchus , Parasuchus)  contains  four  valid  species:  P.  bransoni  (synonyms  P.  parvus , P. 
scurriensis),  P.  neukami,  P.  magnoculus , and  P.  Iiislopi.  Other  nominal  species  based  on  specimens  that  we 
assign  to  Paleorhinus  are  nomina  dubia.  Paleorhinus  is  a constituent  of  late  Carman  faunas  in  the  western 
United  States  (lower  Dockum  Group.  Camp  Springs  Member  of  the  Tecovas  Formation,  lower  Chinle 
Formation,  Popo  Agie  Formation),  Germany  ( Blasensandstein),  Morocco  (Argana  Formation),  India  (Maleri 
and  Tiki  Formations),  and  Austria  (Opponitzer  Beds).  These  faunas,  together  with  correlative  faunas  which 
lack  Paleorhinus  in  Scotland  (Lossiemouth  Sandstone  Formation)  and  South  America  (upper  Santa  Maria  and 
Ischigualasto  Formations),  encompass  a Paleorhinus  biochron  which  can  be  recognized  across  much  of  the 
Late  Triassic  of  Pangaea.  The  age  of  this  biochron  is  based  on  pollen,  marine  invertebrates,  and  radiometric 
dates. 


Palo  Duro  Canyon  in  Randall  County,  Texas  (Text-fig.  1)  contains  one  of  the  most 
extensive  exposures  of  the  Tecovas  and  Trujillo  Formations  of  the  Upper  Triassic.  These  strata  have 
produced  abundant  vertebrate  fossils  elsewhere  (e.g.  Case  1922;  Murry  1982,  1989;  Chatterjee 
1986),  but  relatively  few  from  Palo  Duro  Canyon  (Schaeffer  and  Gregory  1961;  Schaeffer  1967; 
Long  and  Ballew  1985;  Murry  1989).  These  collections  include  specimens  of  the  phytosaur  Rutiodon 
(Murry  1989).  but  no  material  of  the  generally  older  and  more  primitive  phytosaur  Paleorhinus.  The 
nearest  occurrence  of  Paleorhinus  is  about  200  km  to  the  south  at  Home  Creek,  Crosby  County 
(Case  1922).  Here,  we  report  a new  occurrence  of  Paleorhinus  in  Palo  Duro  Canyon,  which  reveals 
a hitherto  unknown  faunal  level  in  the  Upper  Triassic  of  this  area.  Phytosaurs  are  long-snouted, 
semi-amphibious  vertebrates  which  constitute  the  majority  of  specimens  collected  in  the  Upper 
Triassic  strata  of  western  North  America  (Camp  1930;  Gregory  1962). 

The  Paleorhinus  skull  from  Palo  Duro  Canyon,  Texas  was  discovered  in  1966  by  Nick 
Petruccione  and  David  Hughes,  and  collection  was  supervised  by  Jack  T.  Hughes,  Curator  of 
Paleontology  at  the  Panhandle  Plains  Museum.  The  locality  is  P217  in  the  locality  records  of  the 
Panhandle  Plains  Museum  (UTM  3,874,800  m N/  256,850  m E Zone  14),  and  it  lies  just  north  of 
the  northern  boundary  of  Palo  Duro  Canyon  State  Park,  on  the  west  side  of  Palo  Duro  Creek  in 
Randall  County,  Texas  (Text-fig.  1).  The  skull  was  found  in  a basal  conglomerate  unit  of  the  Upper 
Triassic  strata,  0-25  m above  the  Permian  Quartermaster  Formation  (Text-fig.  1),  which  also 
includes  white  sandstone  and  purple  claystone.  This  conglomerate  represents  the  northernmost 
outcrop  of  the  Camp  Springs  Member  of  the  Tecovas  Formation,  a stratigraphic  unit  that  has 
yielded  a skull  of  Paleorhinus  in  Scurry  County,  Texas  (Langston  1949). 

This  article  discusses  the  taxonomic  status  of  the  new  skull,  which  necessitates  a revision  of  the 
genus  Paleorhinus  and  a consideration  of  all  specimens  assigned  to  this  taxon.  The  widespread 
occurrence  of  this  genus  and  its  limited  temporal  range  make  it  ideal  for  intercontinental 
correlation.  The  final  portion  of  this  paper  discusses  the  definition  and  distribution  of  a Paleorhinus 
biochron  throughout  Pangaea. 


| Palaeontology,  Vol.  34,  Part  2,  1991,  pp.  487-501. | 


© The  Palaeontological  Association 


488 


PALAEONTOLOGY,  VOLUME  34 


text-fig.  1.  Geological  map  of  part  of  Palo  Duro  Canyon,  West  Texas  (after  Matthews  1969),  and  a 
stratigraphic  section  showing  the  Paleorhinus  locality. 

Abbreviations.  The  following  institutional  abbreviations  are  used  in  this  paper:  FMNH  UC,  Field  Museum  of 
Natural  History,  University  of  Chicago  Collection,  Chicago,  Illinois;  MNA,  Museum  of  Northern  Arizona, 
Flagstaff,  Arizona;  MU,  University  of  Missouri,  Columbia,  Missouri;  NMMNH,  New  Mexico  Museum  of 
Natural  History,  Albuquerque,  New  Mexico;  PPM,  Panhandle  Plains  Museum,  Canyon,  Texas;  TTUP,  Texas 
Tech.  University,  Lubbock,  Texas;  UMMP,  University  of  Michigan  Museum  of  Paleontology,  Ann  Arbor, 
Michigan;  UT,  University  of  Texas,  Austin,  Texas. 

SYSTEMATIC  PALAEONTOLOGY 

Class  reptilia  Laurenti,  1768 
Subclass  diapsida  Osborn,  1903 
Order  pseudosuchia  Zittel,  1890 
Suborder  phytosauria  Camp,  1930 
Family  phytosauridae  Lydekker,  1888 
paleorhinus  Williston,  1904 

1904  Paleorhinus  Williston,  p.  696,  fig.  6. 

1910  Mesorhinus  Jaekel,  p.  219,  figs  2-6. 

1922  Promystriosuchus  Case,  p.  49,  fig.  21 ; PI.  11a-d. 

1932  Francosuchus  Kuhn,  p.  123,  figs  5 and  6;  PI.  5,  1 and  2. 

1936  Ebrachosuchus  Kuhn,  p.  77,  fig.  4-5;  PI.  8,  la-e;  PI.  10,  1 and  4. 

1961  Mesorhinosuchus  ( Mesorhinus ) Kuhn,  p.  79. 

1978  Parasuchus  Chatterjee,  p.  86,  figs  1-14. 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


489 


60° 


30° 


0° 


30° 


60° 


text-fig.  2.  Paleorhinus  localities  of  the  Late  Triassic  Pangaean  supercontinent.  1,  Popo  Agie  Formation, 
central  Wyoming  (USA).  2.  lowermost  Petrified  Forest  Member  of  the  Chinle  Formation,  northeastern 
Arizona  (USA).  3,  Camp  Springs  Member  of  the  Tecovas  Formation,  Palo  Duro  Canyon,  West  Texas  (USA; 
see  Text-fig.  1).  4,  lower  part  of  undivided  Dockum  Group,  Howard  County,  Texas  (USA).  5,  Argana 
Formation,  Morocco.  6,  Blasensandstein,  West  Germany.  7,  Opponitzer  Beds,  Austria.  8,  Maleri  and  Tiki 

Formation,  India. 


Type  Species.  Paleorhinus  bransoni  Williston,  1904. 

Included  species.  The  type  species  and  P.  hislopi  Lydekker,  1885,  P.  neukami  Kuhn,  1936,  P.  magnoculus  Dutuit, 
1977.  The  following  named  species  are  based  on  specimens  of  Paleorhinus , but  are  nomina  dubia  : Mesorhinus 
fraasi  Jaekel,  1910,  Promystriosuchus  ehlersi  Case,  1922,  Paleorhinus  broilii  Kuhn,  1932,  Francosuchus  lalus 
Kuhn,  1932,  Ebrachosuchus  angustifrons  Kuhn,  1936,  and  cf.  Francosuchus  trauthi  Huene,  1939. 

Distribution.  Popo  Agie  Formation  of  Wyoming,  lower  part  of  Petrified  Forest  Member  of  the  Chinle 
Formation  of  Arizona,  Camp  Springs  Member  of  the  Tecovas  Formation  and  lower  part  of  Dockum  Group 
(undivided)  of  West  Texas,  Blasensandstein  (Germany),  Opponitzer  Beds  (Austria),  Argana  Formation 
(Morocco),  and  Maleri  and  Tiki  Formation  (India)  (Text-fig.  2).  All  these  stratigraphic  units  are  late  Carnian 
(Late  Triassic)  in  age  (see  later  discussion). 


Revised  Diagnosis.  Phytosaurid  that  differs  cranially  from  others  in  the  following  features:  external 
nares  lie  anterior  to  the  antorbital  fenestrae;  dorsal  margin  of  external  nares  is  inclined  anteriorly; 
orbits  are  dorsally  oriented;  and  quadratic  foramina  are  large. 


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text-fig.  3.  Skulls  of  the  three  common  genera  of  Upper  Triassic  phytosaurs  in  North  America,  mid-late 
Carnian  Paleorhinus,  late  Carnian  Rutiodon,  and  Norian  Pseudopalatus.  a-d,  Paleorhinus  (after  Chatterjee 
1978);  a,  lateral  view;  B,  dorsal  view;  c,  ventral  view';  d,  posterior  view,  e-h,  Rutiodon ; E,  lateral  view  (after 
Case  and  White  1934);  f,  dorsal  view  (after  Case  and  White  1934);  G,  ventral  view  (after  Case  1922);  h, 
posterior  view  (after  Case  1922).  i-l,  Pseudopalatus ; i,  lateral  view  (after  Camp  1930);  J,  dorsal  view  (after 
Mehl  1928a);  k,  ventral  view  (after  Mehl  1922);  l,  posterior  view  (after  Mehl  1928a).  Abbreviations:  an, 
antorbital  fenestra;  en,  external  nares;  o,  orbit;  sp,  squamosal  process;  and,  st,  supratemporal  fenestra. 


Discussion.  Paleorhinus  is  the  least  derived  phytosaur  (Ballew  1989)  because  it  has  external  nares 
anterior  to  the  antorbital  fenestrae  and  a posterior  temporal  arcade  at  the  level  of  the  skull  roof 
(Text-fig.  3).  The  contemporary  Angistorhinus  also  has  a high  posterior  temporal  arcade,  but  this 
genus  has  more  posterior  external  nares.  Phytosaurs  of  generally  younger,  Carnian  age  than 
Paleorhinus , such  as  Rutiodon  (Text-fig.  3),  are  characterized  by  external  nares  above  the  antorbital 
fenestrae,  posteriorly-rounded  squamosal  processes  and  a posterior  temporal  arcade  that  is 
wrapped  around  and  under  the  posterior  margin  of  the  skull  roof  with  small  supratemporal 
fenestrae.  Norian  phytosaurs,  such  as  Pseudopalatus , have  slit-like  supratemporal  fenestrae  and 
posteriorly-elongate  squamosal  processes  (Text-fig.  3). 

Several  genera  are  here  considered  subjective  junior  synonyms  of  Paleorhinus  (see  above).  Later 
discussion  will  indicate  why  we  consider  the  type  species  of  these  genera  to  pertain  to  Paleorhinus. 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


491 


text-fig.  4.  Paleorhinus  bransoni , PPM  P217,  incomplete  skull  from  Palo  Duro  Canyon,  West  Texas,  a,  dorsal 
view.  B,  ventral  view,  c,  drawing  of  dorsal  view.  Abbreviations:  af,  antorbital  fenestra;  f,  frontal;  j,  jugal;  1, 
lachrymal.  If,  lateral  fenestra;  n,  external  nares;  na,  nasal;  o,  orbit;  p,  parietal;  pf,  prefrontal;  po,  postorbital; 
pof,  postfrontal;  q,  quadrate;  qf,  quadratic  foramen;  so,  supraoccipital ; sq,  squamosal;  and,  st,  supratemporal 

fenestra. 


Paleorhinus  bransoni  Williston,  1904 
1904  Paleorhinus  bransoni  Williston,  1904,  p.  696,  fig.  6. 

1928/>  Paleorhinus  parvus  Mehl,  p.  142,  figs  1 and  2;  pi.  37.  I 10;  pi.  38,  1-7;  pi.  39.  1 2,  4. 

1949  Paleorhinus  scurriensis  Langston,  p.  325,  figs  1-3. 

Holotype.  FMNH  UC  632,  skull  (Williston  1904,  fig.  6;  Lees  1907,  fig.  1-7). 

Locality  and  Horizon.  Popo  Agie  Formation  (Upper  Triassic)  at  Squaw  Creek,  southeast  corner  of  Township 
3 South,  Range  1 East,  Fremont  County,  Wyoming. 

Referred  specimen.  PPM  P217,  a partial  skull  (Text-fig.  4). 


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Description  of  referred  specimen.  PPM  P217  is  a phytosaur  skull  that  lacks  the  rostrum  anterior  to  the  external 
nares  and  portions  of  the  maxillae  lateral  to  them,  and  all  palatal  elements  anterior  to  the  posterior  portion  of 
the  basisphenoid.  The  maximum  length  of  the  skull  is  414  mm,  with  a maximum  width  of  357  mm,  which  has 
been  increased  by  flattening  of  the  skull.  The  skull  is  relatively  undeformed,  although  the  basioccipital  has  been 
pushed  forward  about  20  mm,  and  the  ventral  portions  of  the  quadrates  have  been  pushed  posteriorly.  The 
main  deformation  is  the  dorsoventral  flattening  evident  in  the  orientation  of  the  quadrates. 

The  external  nares  are  well  forward  of  the  antorbital  fenestrae,  as  is  the  case  with  ‘ Par asuchus'  hislopi 
(Chatterjee  1978),  Paleorhinus  magnoculus  (Dutuit  1977)  and  Paleorhinus  bransoni  (Lees  1907).  The  antorbital 
fenestrae  are  relatively  small.  Although  the  anterior  margins  of  both  antorbital  fenestrae  are  broken,  the 
curvature  of  the  upper  and  lower  margins  of  the  right  fenestra  indicates  its  original  size.  In  dorsal  view,  the 
posterior  margin  of  the  skull  appears  very  wide,  but  this  is  due  to  dorsoventral  distortion.  The  external  nares 
are  inclined  anteriorly.  The  lateral  temporal  fenestrae  are  roughly  square  in  shape  and  have  dorsal  margins  that 
are  longer  than  the  antorbital  fenestrae.  The  quadratic  foramina  are  large  (19  mm  maximum  diameter)  and 
visible  in  dorsal  view  because  of  the  flattening  of  the  skull.  The  sutural  pattern  is  consistent  with  other 
specimens  of  Paleorhinus  (e.g.  Langston  1949;  Chatterjee  1978). 

PPM  P217  is  assigned  to  Paleorhinus  on  the  basis  of  having  external  nares  anterior  to  the  antorbital 
fenestrae,  external  nares  whose  dorsal  margins  incline  anteriorly,  and  the  possession  of  large  quadratic 
foramina.  This  specimen  is  assigned  to  Paleorhinus  bransoni  because  of  the  small  size  of  the  orbits  (cf.  P. 
magnoculus)  and  inclusion  of  the  jugal  in  the  antorbital  fenestrae  (cf.  ‘ Par  asuchus'  hislopi’.  Chatterjee  1978, 
text-fig.  3 a).  The  only  morphological  difference  between  P.  bransoni  and  P.  neukami  is  in  the  length  of  the 
rostrum,  a feature  not  preserved  in  the  new  specimen.  On  the  relatively  weak  grounds  of  geographic  proximity, 
the  new  skull  is  thus  identified  as  Paleorhinus  bransoni. 


PALEORHINUS  TAXONOMY  AND  DISTRIBUTION 


USA 

Wyoming.  Williston  (1904)  named  Paleorhinus  (type  species  P.  bransoni)  for  a skull  from  the  Popo 
Agie  Formation  at  Squaw  Creek  in  the  Wind  River  Mountains  of  western  Wyoming  (Mehl  19286). 
Williston  (1904)  briefly  described  the  genoholotype  of  P.  bransoni , and  subsequently  Lees  (1907) 
described  it  in  detail.  Mehl  (19156,  19286),  Jaekel  (1910)  and  Langston  (1949)  criticized  several  of 
Lees’  (1907)  interpretations  of  the  structure  of  the  Paleorhinus  skull,  but  did  not  doubt  its  generic 
distinctiveness.  Mehl  (1915a,  19156)  demonstrated  that  an  ilium  assigned  to  Paleorhinus  by  Lees 
(1907)  actually  pertains  to  the  rauisuchian  Poposaurus. 

Mehl  (19286)  described  a second  partial  skull  and  skeleton  of  Paleorhinus  (MU  530),  which  he 
named  P.  parvus , from  the  Popo  Agie  Formation  at  Sage  Creek  in  the  same  area  of  Wyoming  as 
the  type  locality  of  P.  bransoni.  The  skull  and  lower  jaw  of  Paleorhinus  parvus , which  is  now  in  three 
pieces,  show  no  major  differences  from  P.  bransoni.  Mehl  (19286,  pp.  155-156)  cited  principally 
differences  in  the  length  of  the  rostrum  and  the  degree  of  downward  deflection  of  the  rostral  tip  to 
distinguish  P.  parvus.  However,  he  ignored  the  large  size  difference  between  the  skulls  of  the  two 
putative  species.  Colbert  (1947)  documented  that  relative  rostral  length  is  proportional  to  skull  size 
in  phytosaurs.  In  addition,  the  deflection  of  the  rostral  tip  of  the  holotype  skull  of  P.  parvus  is 
probably  the  result  of  post-burial  deformation.  Thus,  we  consider  P.  parvus  a subjective  junior 
synonym  of  P.  bransoni. 

Texas.  Case  (1922)  named  Promystriosuchus  ehlersi  for  a badly  fractured  skull  from  the  Tecovas 
Formation  of  Crosby  County,  Texas.  Subsequently,  Gregory  (1962)  included  this  taxon  in 
Paleorhinus.  ‘ Promystriosuchus ’ differs  from  Paleorhinus  bransoni  in  lacking  a posterior  squamosal 
hook  in  lateral  view,  but  this  could  be  the  result  of  damage  to  the  Texas  skull.  The  holotype  skull 
of  Promystriosuchus  ehlersi  (UMMP  V7487)  is  badly  distorted  and  broken  anteriorly  along  the 
midline  so  that,  in  ventral  view,  the  right  tooth  row  is  directed  ventrally,  but  the  left  tooth  row  is 
oriented  laterally.  Also,  the  lateral  aspect  of  the  left  external  naris  is  visible  along  the  split  midline 
of  the  skull.  Gregory  (1962,  pp.  671-673)  criticized  Case’s  (1922)  diagnosis  of  Promystriosuchus 
ehlersi  in  detail.  We  agree  with  Gregory  (1962,  pp.  672-673)  that  all  the  differences  between 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


493 


Paleorhinus  bransoni  and  Promystriosuchus  ehlersi  cited  by  Case  (1922)  are  either  errors  of 
interpretation  or  are  characters  now  recognized  as  variable  within  phytosaur  taxa.  P.  ehlersi 
apparently  differs  from  P.  bransoni  in  having  a median  narial  septum  which  is  not  visible  in  lateral 
view.  However,  the  holotype  is  so  badly  distorted  and  fractured  that  we  consider  P.  ehlersi  a nomen 
dubium  at  the  species  level,  although  its  holotype  clearly  is  a specimen  of  Paleorhinus. 

Langston  (1949)  described  Paleorhinus  scurriensis  from  the  Camp  Springs  Member  of  the  Tecovas 
Formation  at  the  base  of  the  Dockum  Group  in  Scurry  County,  Texas.  The  holotype  (TTVP 
539)  is  a partial  skull  that  is  similar  to  P.  bransoni  in  having  a more  anterior  placement  of  the 
nares  than  in  Promystriosuchus  ehlersi , but  this  is  a variable  feature  within  the  genus  Paleorhinus 
(Gregory  1962).  Langston  (1949,  p.  325)  used  qualitative  criteria  to  distinguish  this  species, 
including  exceptionally  large  palatine  foramina,  moderately  elongate  posttemporal  fenestrae,  and 
dorso-ventral  flattening  of  the  skull.  We  do  not  consider  these  characters  diagnostic,  because  the 
palate  of  most  species  of  Paleorhinus  is  poorly  known,  fenestral  shape  is  subject  to  postmortem 
deformation,  and  most  Paleorhinus  skulls  are  dorso-ventrally  flattened.  We  are  thus  unable  to 
diagnose  P.  scurriensis  as  a species  separate  from  P.  bransoni. 

Six  other  undescribed  skulls  of  Paleorhinus  are  known  from  Texas,  one  from  the  ?lower  Tecovas 
of  Borden  County  (LIT  31213)  and  five  from  the  lower  Dockum  Group  of  Howard  County  (UT 
31100-453,  31100-101,  31100-239,  31100-418,  31025-172;  Gregory  1962;  Shelton  1984).  Shelton 
(1984)  referred  all  these  specimens  to  P.  scurriensis.  However,  as  argued  above,  P.  scurriensis  and 
Promystriosuchus  ehlersi  are  both  conspecific  with  P.  bransoni.  Indeed,  we  have  examined  these 
specimens,  and  conclude  that  all  the  Texas  Paleorhinus  material  represents  one  taxon,  P.  bransoni. 

Arizona.  A small  fragment  of  a Paleorhinus  skull  (MNA  V2698)  has  been  collected  from  the  Downs 
quarry  in  the  lowermost  levels  of  the  Petrified  Forest  Member  of  the  Chinle  Formation  in  Apache 
County  (Murry  and  Long  1989).  This  specimen  has  external  nares  anterior  to  the  antorbital 
fenestrae,  but  cannot  be  identified  beyond  Paleorhinus  sp. 

New  Mexico.  Toepelman  (1916,  fig.  1)  described  a partial  phytosaur  rostrum  from  the  Bluewater 
Creek  Member  of  the  Chinle  Formation  at  Fort  Wingate,  McKinley  County  (Lucas  and  Hayden 
1989)  as  ? Paleorhinus.  However,  this  fragment  is  not  diagnostic  below  the  subordinal  level  (Hunt 
and  Lucas  1989).  Thus,  there  are  no  known  occurrences  of  Paleorhinus  in  New  Mexico. 

Eastern  USA.  Paleorhinus  has  not  been  reported  from  the  Newark  Supergroup  of  eastern  North 
America  (USA  and  Canada).  Historically,  and  recently,  most  phytosaur  specimens  from  the 
Newark  have  been  assigned  to  Rutiodon , regardless  of  how  fragmentary  the  material  is  (e.g.  Olsen 
1989u.  fig.  9.7).  However,  much  of  the  Newark  is  Carnian  in  age,  so  it  is  possible  that  some  of  the 
fragmentary  phytosaur  material  represents  Paleorhinus.  More  complete  specimens  will  be  needed  to 
evaluate  this  possibility. 

Morocco 

Dutuit  (1977)  described  a nearly  complete  phytosaurid  skull  from  the  Argana  Formation  as 
Paleorhinus  magnoculus . This  species  differs  from  other  species  of  Paleorhinus  in  the  enormous  size 
of  the  orbits  and,  possibly,  in  the  exclusion  of  the  jugal  from  the  antorbital  fenestra. 

India 

Huxley  (1870)  used  the  name  Parasuchus  in  a table,  and  this  taxon  was  validated,  and  the  species 
P.  hislopi  named,  by  Lydekker  (1885)  for  fragmentary  reptilian  fossils  from  the  Maleri  Formation 
of  the  Pranhita-Godavari  Valley.  Subsequently,  Huene  (1940)  identified  one  of  these  fragments  as 
a basicranium  of  the  rhynchosaur  Paradapedon.  The  phytosaur  specimens  have  since  been  referred 
to  aff.  Brachysuchus  maleriensis  by  Huene  (1940)  and  to  Phytosaurus  maleriensis  by  Colbert  (1958). 
Gregory  (1962)  concluded  that  the  type  specimens  of  Parasuchus  hislopi  were  generically 
indeterminate.  Chatterjee  (1974)  designated  a phytosaur  rostral  fragment  from  among  the  syntypes 


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PALAEONTOLOGY,  VOLUME  34 


as  the  lectotype  of  Parasuchus  hislopi , but  this  specimen  is  generically  indeterminate,  and  thus  the 
taxon  is  a nomen  dubium.  Virtually  complete  skeletons  of  a phytosaur  have  been  collected  from  the 
Maleri  Formation,  and  other  specimens  have  been  obtained  from  the  Tiki  Formation  of  the 
Son-Mahanadi  Valley  (Chatterjee  1967,  1978).  Chatterjee  (1978)  referred  these  specimens  to 
Parasuchus , but  we  follow  Ballew  (1989)  in  assigning  them  to  Paleorhinus.  Although  the  lectotype 
of  Parasuchus  hislopi  may  be  a nomen  dubium , we  provisionally  use  the  binominal  Paleorhinus  hislopi 
for  all  relevant  specimens  of  ‘ Parasuchus'  pending  a restudy  of  all  the  Indian  specimens.  The  Indian 
species  (P.  hislopi)  apparently  differs  from  other  species  of  Paleorhinus  in  lacking  interpterygoid 
vacuities  in  the  palate. 

West  Germany 

Kuhn  (1932,  1936)  erected  two  genera  and  four  species  of  phytosaurs  from  the  Carnian 
Blasensandstein  at  Ebrach  in  Franconia.  These  taxa,  Francosuchus  broilii , F.  latus , Ehrachosuchus 
angustifrons  and  E.  neukami , are  morphologically  very  similar  to  Paleorhinus.  Indeed,  Gregory 
(1962)  and  Westphal  (1976)  placed  these  taxa  in  a subgenus  Francosuchus  of  the  genus  Paleorhinus. 
Chatterjee  (1978)  considered  the  specimens  Kuhn  described  to  represent  the  genus  Francosuchus , 
which  he  placed  in  a different  subfamily  from  Paleorhinus.  However,  the  only  major  difference 
between  the  Ebrach  specimens  and  other  specimens  of  Paleorhinus  is  rostral  length  (Gregory  1962). 
Francosuchus  broilii  was  originally  reconstructed  with  a short  snout  (Kuhn  1932),  but  Kuhn  (1936, 
p.  65)  later  realised  that  a portion  of  the  snout  was  missing.  The  holotypes  of  F.  latus  (Kuhn  1932, 
fig.  5)  and  E.  angustifrons  both  lack  complete  rostra,  but  that  of  E.  neukami  has  a very  elongate 
rostrum  (Kuhn  1936,  pi.  8,  la-e).  It  is  principally  on  the  basis  of  the  elongate  rostrum  of  E.  neukami 
that  Gregory  (1962)  and  Westphal  (1976)  placed  all  the  Ebrach  phytosaurs  in  a distinct  subgenus 
from  other  Paleorhinus  specimens.  However,  rostral  length  is  a variable  feature  among  phytosaurs 
(Gregory  1962),  and  we  consider  it  a feature  of  taxonomic  value  only  at  the  species  level.  Therefore, 
we  do  not  uphold  separate  generic  or  subgeneric  status  for  Ehrachosuchus  or  Francosuchus. 

Chatterjee  (1978)  considered  Francosuchus  to  be  a separate  genus  on  the  basis  of  the  position  of 
the  external  nares  relative  to  the  antorbital  fenestrae,  which  is  a variable  character  (Gregory  1962), 
and  the  absence  of  posterior  squamosal  processes.  However,  the  Ebrach  skulls  that  have  undamaged 
posterior  margins  exhibit  posterior  squamosal  processes  (Kuhn  1936,  pi.  8,  la;  pi.  10,  5).  Thus,  we 
believe  the  taxonomic  disposition  of  the  Ebrach  skulls  should  be  to  consider  Paleorhinus  neukami 
a distinct  species  based  on  its  elongate  rostrum,  and  to  refer  the  other  nominal  taxa  to  Paleorhinus 
sp.  because  they  lack  diagnostic  features. 

Kuhn  (1936)  established  another  new  phytosaur  taxon  from  Ebrach,  Ebrachosaurus  singularis , 
that  is  obviously  a Stagonolepis-hke  aetosaur,  as  noted  by  Benton  and  Walker  (1985)  (compare 
Kuhn  1936,  pi.  13,  4 with  Walker  1961,  fig.  16,  and  Kuhn  1936,  pi.  11,  1-3  with  Walker  1961,  fig. 
20a-o).  Kuhn  also  identified  a lower  jaw  from  Ebrach  as  Mystriosuchus , a Norian  genus,  but  this 
specimen  is  indeterminate  (Gregory  1962). 

In  1910,  Jaekel  described  a phytosaur  skull,  supposedly  from  the  Buntsandstein  (Lower  Triassic) 
of  Bernberg,  as  a new  genus,  Mesorhinus.  There  are  several  problems  with  this  taxon.  The  holotype 
was  found  to  have  a label  that  read  Trematosaurus  (a  labyrinthodont  taxon:  Jaekel  1910).  The 
specimen  is  undoubtedly  a phytosaur,  but  the  label  with  the  specimen  indicated  that  it  was  from  the 
Early  Triassic,  whereas  all  other  phytosaur  taxa  are  restricted  to  the  Late  Triassic  (Jaekel  1910; 
Gregory  1962).  Also,  the  holotype  was  destroyed  in  the  Second  World  War  (Gregory  1962).  Jaekel 
(1910)  attempted  to  verify  the  locality  data  on  the  label  by  examining  the  matrix  around  the 
specimen  and  concluded  that  it  was,  indeed,  from  the  Buntsandstein,  but  this  cannot  now  be 
checked. 

Kuhn  (1961)  substituted  the  name  Mesorhinosucluts  for  Mesorhinus  because  this  name  was 
preoccupied  by  that  of  a South  American  fossil  mammal  (Ameghino  1885).  Recent  authors  have 
either  considered  Mesorhinosuchus  Kuhn,  1961  ( = Mesorhinus  Jaekel,  1910)  a tentative  synonym  of 
Paleorhinus  (Gregory  1962;  Westphal  1976)  or  as  indeterminate  (Chatterjee  1978).  Mesorhinosuchus 
is  undoubtedly  a phytosaur  (Walker  1968,  p.  11;  contra  Gregory  1962,  p.  675)  of  Pa/eorhinus-\ike 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


495 


morphology.  It  differs  from  all  other  adult  phytosaurs  in  retaining  a small  pineal  foramen  (Jaekel 
1910;  Camp  1930),  although  the  holotype  of  P.  scurriensis  has  a shallow  pit  in  this  region  (Langston 
1949).  Mesorhinosuchus  is  best  considered  as  Paleorhinus  sp.  on  the  basis  of  the  anterior  placement 
of  the  nares.  The  age  of  the  specimen  must  be  considered  indeterminate. 

A ustria 

Huene  (1939)  coined  the  name  cf.  Francosuchus  trauthi  for  a skull  fragment  of  a phytosaur  collected 
in  1905  near  Lunz  (about  1 10  km  southwest  of  Vienna),  Austria.  This  specimen  was  derived  from 
dark  gray  to  black  shale  of  the  lower  part  of  the  Opponitzer  Schichten  (Opponitzer  Kalk  of  some 
authors)  (Trauth  1948,  p.  90).  The  Opponitzer  Schichten  of  the  Northern  Alps  are  a predominantly 
marine-limestone  unit  of  late  Carnian  (Tuvalian)  age  (Janoscheck  and  Matura  1980;  H.  Zapfe, 
written  comm.,  1989).  The  skull  fragment  Huene  named  cf.  Francosuchus  trauthi  clearly  pertains  to 
Paleorhinus  and  thus  establishes  a link  between  the  nonmarine  occurrence  of  Paleorhinus  and 
Triassic  marine  biochronology. 

This  skull  fragment  is  number  1905/13  in  the  collection  of  the  Naturhistorisches  Museum  of 
Vienna  (a  sharp  resin  cast  is  NMMNM  P-12960)  and  was  illustrated  by  Huene  (1939,  fig.  la-c), 
Trauth  (1948,  fig.  14;  pi.  12,  figs  6 and  7)  and  Westphal  (1976,  fig.  7c).  It  is  assignable  to  Paleorhinus 
because  the  external  nares  are  obviously  forward  of  the  antorbital  fenestae  and  lie  on  the  posterior 
portion  of  the  rostrum.  This  specimen,  nevertheless,  exhibits  no  other  diagnostic  characters  and  is 
here  referred  to  Paleorhinus  sp. 


THE  PALEORHINUS  BIOCHRON 

Cope  (1875)  first  used  fossil  vertebrates  to  determine  the  age  of  red  beds  in  the  American  West  that 
we  now  recognize  to  be  of  Late  Triassic  age.  Subsequently,  Huene  (1922a,  19226,  1926)  established 
a crude  biochronology  within  these  red  beds,  based  principally  on  phytosaurs.  Huene  (1926,  pp.  3, 
4)  noted  that  ‘parasuchians  such  as  Palaeorhinus  [sic]...,  having  a supratemporal  fenestra  with  a 
high  posterior  border,  are  relatively  primitive  and  could  not  possibly  be  of  Upper  Triassic  age’  in 
contrast  to  phytosaurs  from  higher  stratigraphic  levels  such  as  ‘ IPhytosaurus  dough ti ” [sic]  which 
he  thought  were  of  Late  Triassic  age. 

Camp  (1930),  in  the  course  of  his  revision  of  the  phytosaurs,  realized  that  Huene’s  two  faunas 
were  both  of  Late  Triassic  age  and  refined  the  biochronology  to  recognize  four  successive  faunas. 
Camp  (1930),  like  Huene  (1926),  realized  that  Paleorhinus  is  more  primitive  than  other  phytosaurs, 
although  he  failed  to  recognize  that  Promystriosuchus  is  congeneric  with  Paleorhinus. 

Gregory  (1962)  published  the  next  revision  of  the  phytosaurs,  and,  in  a series  of  articles  (Gregory 
1956,  1969;  Colbert  and  Gregory  1957),  he  outlined  a worldwide  biochronology  for  the  Late 
Triassic  based  on  vertebrate  faunas.  Gregory  (1956,  1969)  recognized  four  faunas  in  North 
America,  the  oldest  of  which  was  defined  by  the  co-occurrence  of  the  phytosaurs  Paleorhinus  and 
Angistorhinus.  Gregory  (1956,  1969)  correlated  this  fauna  with  the  Blasensandstein  of  Germany. 
Chatterjee  (1978)  and  Ballew  (1989)  subsequently  used  the  occurrence  of  Paleorhinus  to  correlate 
the  Argana  Formation  of  Morocco  and  the  Maleri  and  Tiki  Formations  of  India  with  the 
Blasensandstein. 

Paleorhinus  occurs  with  faunas  that  are  distinct  from  those  of  overlying  or  underlying  strata  and 
which  vary  geographically.  The  phytosaur  Angistorhinus  occurs  in  several  faunas  with  Paleorhinus 
(Popo  Agie,  lower  Dockum,  Argana).  The  co-occurrence  of  the  rhynchosaur  Hvperodapedon  with 
Paleorhinus  in  the  Maleri  Formation  (Benton  1983)  is  strong  evidence  to  suggest  that  the 
Lossiemouth  Sandstone  Formation  of  Scotland  and  the  Wolfville  Formation  of  Nova  Scotia,  which 
also  contain  Hvperodapedon  (Benton  1983;  Olsen  19896),  are  also  of  the  same  age  ( contra  Cooper 
1982).  A complicating  factor  is  that  the  Lossiemouth  fauna  also  includes  the  aetosaur  Stagonolepis 
(Walker  1961;  Benton  and  Walker  1985)  which  occurs  in  North  America  (Calyptosuchus  of  Long 
and  Ballew  1985)  with  post- Paleorhinus  phytosaurs  (Murry  and  Long  1989). 


496 


PALAEONTOLOGY,  VOLUME  34 


The  Ischigualasto  Formation  of  Argentina  and  the  upper  Santa  Maria  Formation  of  Brazil 
contain  the  rhynchosaur  Scaphonyx  which  is  very  similar  to  Hyperodapedon  (Benton  1983)  and  are 
also  probably  of  the  same  age.  The  Ischigualasto,  Santa  Maria,  and  Lossiemouth  Sandstone 
Formations  contain  terrestrial  faunas  that  lack  semiaquatic  taxa  such  as  phytosaurs.  Other  tetrapod 
taxa  that  are  found  in  Paleorhinus- bearing  or  equivalent  faunas  are  aetosaurs  (lower  Dockum  - 
Longosuchus;  Blasensandstein  - Ebrachosuchus ; Maleri  - undescribed;  Ischigualasto/Santa 

Maria  - Aetosauroides ; Lossiemouth/lower  Chinle  - Stagonolepis ),  metoposaurs  (Popo  Agie,  lower 
Dockum,  Blasensandstein,  Maleri,  Argana),  dicynodonts  (Popo  Agie,  Argana,  Ischigualasto),  and 
rauisuchians  (Popo  Agie,  lower  Dockum,  Maleri,  Ischigualasto).  Few  of  these  taxa  aid  in 
correlation  with  the  North  American  Late  Triassic,  but  the  rauisuchian  Poposaurus  occurs  in  the 
Popo  Agie  and  the  lower  Dockum,  and  indistinguishable  metoposaurs  (Hunt  1989c/)  occur  in  the 
lower  Dockum  (. Buettneri  howardensis ),  Maleri  (Metoposaurus  maleriensis ),  Argana  ( Metoposaurus 
azerouali)  and  the  Wolfville  and  Camp  Springs  ( Buettneria  bakeri : Case  1932;  Baird  1986).  In 
addition,  the  dicynodont  Moghreberia  from  the  Argana  (Dutuit  1988)  is  very  similar  to  Placerias 
from  the  lowermost  Chinle  (Camp  and  Welles  1956)  and  they  may  be  congeneric  (Lucas  1990). 
Thus,  the  aetosaurs,  metoposaurs,  dicynodonts  and  rauisuchians  that  occur  in  Paleorhinus-beanng 
strata  or  their  equivalents  are  distinct  from  taxa  in  underlying  and  overlying  strata. 

In  the  western  United  States  and  Germany,  Paleorhinus-bearmg  faunas  are  succeeded  by  faunas 
dominated  by  other  phytosaur  taxa.  There  are  only  two  occurrences  of  overlap  between  Paleorhinus 
and  more  derived  phytosaurs.  At  the  Downs’  quarry  in  the  lower  Petrified  Forest  Member  of  the 
Chinle  Formation  in  northeastern  Arizona,  a single  skull  fragment  of  Paleorhinus  (MNA  V 2698) 
co-occurs  with  the  phytosaur  Rutiodon.  The  remainder  of  the  Chinle  phytosaur  fauna  is  dominated 
by  fossils  of  Rutiodon  and  Pseudopalatus.  At  Home  Creek  in  Crosby  County,  Texas,  Case  (1922) 
reported  the  presence  of  Paleorhinus  (=  Promystriosuchus ),  but,  subsequently,  only  specimens  of 
Rutiodon  have  been  found  in  this  area  (Gregory  1972).  However,  Case  (1922)  did  not  give  exact 
geographic  or  stratigraphic  information  about  his  locality,  and  the  Paleorhinus-bearmg  Camp 
Springs  Member  does  crop  out  in  this  area  (Finch  and  Wright  1983;  Finch  et  al.  1976).  Thus,  the 
two  taxa  of  phytosaurs  may  not  co-occur  in  the  same  fauna  in  West  Texas. 

Paleorhinus  occurs  with  faunas  distinct  from  those  of  overlying  and  underlying  strata  that  can  be 
correlated  throughout  much  of  the  world,  and  this  taxon  exhibits  negligible  stratigraphic  overlap 
with  other  phytosaurs  (Text-fig.  5).  Therefore,  we  recognize  a Paleorhinus  biochron  (Lucas  and 
Hunt  1989)  that  has  biochronological  utility  across  Pangaea. 

The  faunas  that  contain  Paleorhinus  have  been  considered  Carnian  in  age  by  all  recent  authors 
(Murry  1982,  1986,  1989;  Lucas  et  al.  1985 ; Chatterjee  1986;  Olsen  and  Sues  1986;  Lucas  and  Hunt 
1989;  Ballew  1989).  Data  from  palynology  (lower  Dockum,  Blasensandstein),  radiometric  dating 


W-CENTRAL 

WYOMING 

(USA) 


ST.  JOHNS 
ARIZONA 
(USA) 


RANDALL  & 
CROSBY  CO. 
TEXAS  (USA) 


HOWARD  CO. 
TEXAS 
(USA) 


SOUTHERN 

WEST 

GERMANY 


AUSTRIA 


MOROCCO 


CENTRAL 

INDIA 


POPO  AGIE 
FORMATION 


4m 


TRUJILLO  FM. 


UNTERER 

BURGSANDSTEIN 


HAUPTDOLOMIT 


main  body 


OPPONITZER 

SCHICHTEN 


Camp  Springs 
Member 


DOCKUM  GROUP 
(undivided) 


BLASENSANDSTEIN 


LUNZ 

SCHICHTEN 


ARGANA 

FORMATION 


MALERI 

FORMATION 


• PALEORHINUS  OCCURRENCES 


text-fig.  5.  Correlation  of  Upper  Triassic  Paleorhinus-bearing  strata  of  Pangaea.  See  text  for  discussion. 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


497 


(Ischigualasto)  and  marine  invertebrates  (Opponitzer  Beds)  have  the  potential  of  giving  a more 
refined  age  for  these  faunas. 

Paleorhinus  sp.  from  the  Opponitzer  Beds  from  near  Lunz  in  Austria  was  found  associated  with 
an  upper  Carnian  brackish  marine  fauna  (Huene  1939;  Westphal  1976).  This  specimen  thus  can  be 
correlated  into  the  standard  marine  sequence  of  the  Alpine  province,  via  ammonites  and  pollen,  that 
indicate  it  is  of  Tuvalian  age  (late  Carnian:  Janoscheck  and  Matura  1980).  This  ties  the  Paleorhinus 
biochron  to  Triassic  marine  biochronology. 

The  Ischigualasto  Formation  of  the  Ischigualasto-Ischichuca  basin  of  northwestern  Argentina  is 
associated  with  basalt  and  diabases  which  yield  radiometric  ages  with  a mean  of  224  + 5 Ma 
(Gonzales  and  Toselli  in  Valencio  et  al.  1975).  This  date  may  be  judged  as  approximately  mid 
Carnian  in  age  (Forster  and  Warrington  1985),  but  the  spread  of  radiometric  dates  from  the 
Ischigualasto  is  from  early  Carnian  to  early  Norian  (Forster  and  Warrington  1985). 

The  age  relationships  of  strata  of  the  Middle  Keuper  in  Germany  are  somewhat  controversial 
despite  palynological  studies  (Benton  1986).  The  Blasensandstein,  which  contains  Paleorhinus , is 
equivalent  to  part  of  the  Rote  Wand  of  southwestern  Germany  which  has  been  considered  earliest 
Norian  or  early  late  Carnian  in  age  (Fisher  1972;  Fisher  and  Bujak  1975;  Kozur  1975;  Gall  et  al., 
1977;  Schroeder  1982).  We  prefer  the  latter  correlation,  as  we  believe  that  the  unconformity  at  the 
base  of  the  Stubensandstein  may  correlate  with  unconformities  in  other  parts  of  the  world  that 
reflect  a major  eustatic  fall  of  sea-level  at  the  Carnian-Norian  boundary  (Embry  1988). 

Dunay  (1972)  attempted  to  compare  the  palynology  of  the  Paleorhinus  and  ‘ Phytosaurus' 
( Rutiodon ) zones  of  Gregory  in  the  Tecovas  Formation.  However,  Dunay’s  (1972)  samples  from  the 
Paleorhinus  zone  were  from  Crosby  County  where,  as  he  noted,  Rutiodon  is  also  found,  and  there 
are  no  good  locality  data  for  the  older  collections.  Therefore,  he  may  have  sampled  a Paleorhinus 
fauna,  a Rutiodon  fauna,  or  a transitional  fauna  that  contains  both  (cf.  Downs’  quarry).  However, 
Dunay  (1972;  Dunay  and  Fisher  1979)  was  certain  that  the  palynofloras  of  the  Tecovas  Formation 
and  the  overlying  Trujillo  Formation  were  late  Carnian  in  age.  Litwin  (1986)  concluded  that  the 
lower  Chinle  Formation  in  Arizona  that  contains  Rutiodon , a taxon  characteristic  of  post- 
Paleorhinus  strata  in  Texas,  was  also  late  Carnian  in  age.  Palynological  evidence  thus  suggests  that 
the  Paleorhinus  biochron  is  of  late-middle  (middle  Tuvalian),  but  not  latest  Carnian  age. 

Ash  (1980)  reviewed  the  biochronology  of  megafossil  plants  in  North  America  and  proposed  a 
number  of  ‘floral  zones’.  The  only  Paleorhinus- bearing  stratigraphic  unit  that  also  contains 
megafossil  plants  is  the  Popo  Agie  Formation  which  Ash  (1980)  placed  in  his  Eoginkgoites  ‘floral 
zone’  of  middle  Carnian  age.  This  age  determination  was  based  on  palynological  studies  of  the 
Newark  Supergroup  in  Eastern  North  America  (Cornet  1977)  and  vertebrate  correlations. 
However,  Ash  (1980)  only  tentatively  placed  the  Popo  Agie  flora  in  this  zone,  and  the  name-bearing 
taxon  is  only  represented  by  ? Eoginkgoites.  Thus,  we  have  little  confidence  in  assigning  a middle 
Carnian  age  to  the  Popo  Agie  from  the  megafossil  plants.  Instead,  we  conclude  that  the  Popo  Agie 
is  of  late  Carnian  age. 

Dutuit  (1983)  explained  the  cosmopolitan  nature  of  Late  Triassic  faunas  dominated  by 
phytosaurs  and  metoposaurs  as  being  due  to  marine  dispersal  by  these  animals.  However,  there  is 
no  evidence  that  these  animals  lived  in  marine  conditions,  and  there  are  terrestrial  rather  than 
marine  connections  between  most  occurrences  of  these  faunas  (Buffetaut  and  Martin  1984). 
Paleorhinus  was  a cosmopolitan  taxon  in  the  late  Carnian,  but  phytosaur  taxa  in  the  Norian  are 
more  restricted  in  their  distribution  (Ballew  1989).  A similar  situation  is  seen  in  metoposaurs  (Hunt 
19896)  and  these  changes  reflect  increased  provincialization  of  faunas  towards  the  end  of  the  Late 
Triassic. 

Acknowledgements.  We  thank  B.  Harrison  (PPM)  for  allowing  us  to  borrow  PPM  P217,  R.  A.  Long 
(University  of  California  Museum  of  Paleontology)  for  bringing  some  literature  to  our  attention,  H.  Zapfe 
(Osterreich  Akadamie  der  Wissenschaft)  for  information  about  the  provenance  of  cf.  ‘ Francosuchus  trauthi', 
H.  A.  Kollman  (Naturhistorisches  Museum,  Wien)  for  a cast  of  cf.  ‘ Francosuchus  trauthi ’,  two  anonymous 
reviewers  for  their  comments,  M.  J.  Benton  for  editorial  assistance,  and  the  New  Mexico  Museum  of  Natural 
History  for  support. 


498 


PALAEONTOLOGY,  VOLUME  34 


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— and  bujak,  j.  1975.  Upper  Triassic  palynofloras  from  Arctic  Canada.  Geoscience  and  Man,  11, 
78-94. 

forster,  s.  c.  and  Warrington,  G.  1985.  Geochronology  of  the  Carboniferous,  Permian  and  Triassic.  99-1 13. 
In  snelling,  N.  j.  ( ed . ).  The  chronology  of  the  geological  record.  Geological  Society  of  London,  London, 
340  pp. 

gall,  j.-c.,  durand,  m.  and  muller,  e.  1977.  Le  Trias  de  part  d'autre  du  Rhin.  Correlations  entre  les  marges 
et  le  centre  du  bassin  germanique.  Bulletin  du  Bureau  de  Recherches  geologiques  et  minieres,  3,  193-204. 
Gregory,  j.  t.  1956.  Significance  of  fossil  vertebrates  for  correlation  of  Late  Triassic  continental  deposits  of 
North  America.  International  Geological  Congress,  20  (2),  7-25. 

1962.  The  genera  of  phytosaurs.  American  Journal  of  Science  260,  652-690. 

- 1969.  Evolution  und  interkontinentale  Beziehungen  der  Phytosauria  (Reptilia).  Palaontologisches 
Zeitschrift , 43,  37-51. 

- 1972.  Vertebrate  faunas  of  the  Dockum  Group,  Triassic,  eastern  New  Mexico  and  West  Texas.  New 
Mexico  Geological  Society  Guidebook,  23,  120-123. 

huene,  f.  von  1922u.  Neue  Beitrage  zur  Kenntnis  der  Parasuchier.  Jahrbuch  Preussische  Geo/ogische 
Landesanstalt,  42,  59-160. 

1922h.  Kurzer  Ueberblick  fiber  die  triassische  Reptilordnung  Thecodontia.  Centralblatt  fur  Mineralogie, 
Geologie  und  Paldontologie,  1922,  408-415. 

1926.  Notes  on  the  age  of  the  continental  Triassic  beds  in  North  America  with  remarks  on  some  fossil 
vertebrates.  Proceedings  of  the  United  States  National  Museum,  69  (18),  1-10. 

1939.  Ein  primitiv  Phytosaurier  in  der  jungeren  nordostalpin  Trias.  Zeitschrift  fiir  Mineralogie,  Geologie 
und  Paldontologie,  1939,  139-144. 

1940.  The  tetrapod  fauna  of  the  Upper  Triassic  Maleri  beds.  Palaeontologia  Indica , 32,  1-42. 

hunt,  a.  p.  1989n.  Comments  on  the  taxonomy  of  Late  Triassic  metoposaurs  and  a preliminary  phylogenetic 
analysis  of  the  family  Metoposauridae.  293-300.  In  lucas,  s.  g.  and  hunt,  a.  p.  (eds).  Dawn  of  the  age  of 
dinosaurs  in  the  American  Southwest.  New  Mexico  Museum  of  Natural  History,  Albuquerque,  414  pp. 

I989A  The  biochronological  significance  of  Late  Triassic  metoposaurid  labyrinthodonts.  New  Mexico 
Journal  of  Science,  29,  1 17-1 18. 

— and  lucas,  s.  G.  1989.  Late  Triassic  vertebrate  localities  in  New  Mexico.  72-101.  In  lucas,  s.  g.  and  hunt, 
a.  p.  (eds).  Dawn  of  the  age  of  dinosaurs  in  the  American  Southwest.  New  Mexico  Museum  of  Natural 
History,  Albuquerque,  414  pp. 

huxley,  t.  h.  1870.  On  the  classification  of  Dinosauria,  with  observations  on  the  Dinosauria  ot  the  Trias. 

Quarterly  Journal  of  the  Geological  Society  of  London,  26,  32-51. 
jaekel,  o.  1910.  Ueber  einen  neuen  Belodonten  aus  dem  Buntsandstein  von  Bernburg.  Sitzungsberichte 
Gesellschaft  naturforschender  Freunde  zu  Berlin,  5,  197-229. 
janoscheck,  w.  R.  and  matura,  A.  1980.  Austria.  1-88.  In  anonymous  (ed.).  Geology  of  the  European  countries. 
Dunod,  Paris,  433  pp. 

kozur,  h.  1975.  Probleme  der  Triasgliederung  und  Parallelisiering  der  germanischen  und  tethyalen  Trias.  Teil 
II:  Anschluss  der  germanischen  Trias  an  die  internationale  Triasgliedering.  Freiberger  Forschungshefte , 
Reihe  C,  3,  58-65. 

kuhn,  o.  1932.  Labyrmthodonten  und  Parasuchier  aus  dem  mittleren  Keuper  von  Ebrach  in  Oberfranken. 
Neues  Jahrbuch  fiir  Mineralogie,  Geologie  und  Paldontologie,  69B,  94—144. 


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— 1936.  Weitere  Parasuchier  und  Labyrinthodonten  aus  dem  Blasensandstein  des  mittleren  Keuper  von 
Ebrach.  Palaeontographica , Abteilung  A , 83,  61-98. 

— 1961.  Die  Familien  der  rezenten  und  fossilen  Amphibien  und  Reptilien.  Verlagshus  Meisenbacli  KG, 
Bamberg,  79  pp. 

langston,  w.  jr.  1949.  A new  species  of  Paleorhinus  from  the  Triassic  of  Texas.  American  Journal  of  Science , 
247,  324-371. 

lees,  J.  H.  1907.  The  skull  of  Paleorhinus.  Journal  of  Geology , 15,  121-151. 

litwin,  R.  J.  1986.  The  palynostratigraphy  and  age  of  the  Chinle  and  Moenave  formations,  southwestern  USA. 

Unpublished  Ph  D.  thesis,  Pennsylvania  State  University. 
long,  R.  a.  and  ballew,  k.  l.  1985.  Aetosaur  dermal  armor  from  the  Late  Triassic  of  the  southwestern  North 
America,  with  special  reference  to  material  from  the  Chinle  Formation  of  Petrified  Forest  National  Park. 
Museum  of  Northern  Arizona  Bulletin , 54,  35-68. 
lucas,  s.  G.  1990.  Toward  a vertebrate  biochronology  of  the  Triassic.  Albertiana , in  press. 

— and  hayden,  s.  N.  1989.  Triassic  stratigraphy  of  west-central  New  Mexico.  New  Mexico  Geological 
Society  Guidebook , 40.  191-211. 

— and  hunt,  a.  p.  1989.  Vertebrate  biochronology  of  the  Late  Triassic.  28th  International  Geological 
Congress  Abstracts , 2,  335-336. 

— and  morales,  m.  1985.  Stratigraphic  nomenclature  and  correlation  of  Triassic  rocks  of  east-central 
New  Mexico:  a preliminary  report.  New  Mexico  Geological  Society  Guidebook  36,  171-184. 
lydekker,  R.  1885.  Maleri  and  Denwa  Reptilia  and  Amphibia.  Palaeontologia  Indica , Series  4 , 1,  1-38. 
Matthews,  w.  a.  in.  1969.  The  geologic  story  of  Palo  Duro  Canyon.  Bureau  of  Economic  Geology , University 
of  Texas,  Guidebook , 8,  1-51. 

mehl,  m.  G.  1915a.  Poposaurus  gracilis,  a new  reptile  from  the  Triassic  of  Wyoming.  Journal  of  Geology,  23, 
516-522. 

19156.  The  Phytosauria  of  the  Trias.  Journal  of  Geology,  23,  129-165. 

1922.  A new  phytosaur  from  the  Trias  of  Arizona.  Journal  of  Geology,  30.  144-157. 

- 1928a.  Pseudopalatus  pristinus , a new  genus  and  species  of  phytosaur  from  Arizona.  University  of 
Missouri  Studies,  3,  1-22. 

— 19286.  The  Phytosauria  of  the  Wyoming  Triassic.  Denison  University  Journal  of  Scientific  Laboratories, 
23.  141-172. 

murry,  p.  a.  1982.  Biostratigraphy  and  paleoecology  of  the  Dockum  Group  (Triassic)  of  Texas.  Unpublished 
Ph  D.  thesis.  Southern  Methodist  University. 

1986.  Vertebrate  paleontology  of  the  Dockum  group,  western  Texas  and  eastern  New  Mexico.  109-137. 
In  padian,  K.  (ed.).  The  beginning  of  the  age  of  dinosaurs : faunal  change  across  the  Triassic -Jurassic  boundary. 
Cambridge  University  Press,  Cambridge,  378  pp. 

1989.  Geology  and  paleontology  of  the  Dockum  Formation  (Upper  Triassic),  West  Texas  and  eastern 
New  Mexico.  102-144.  In  lucas,  s.  g.  and  hunt,  a.  p.  (eds).  Dawn  of  the  age  of  the  dinosaurs  in  the  American 
Southwest.  New  Mexico  Museum  of  Natural  History,  Albuquerque,  New  Mexico,  414  pp. 

— and  long.  r.  a.  1989.  Geology  and  paleontology  of  the  Chinle  Formation,  Petrified  Forest  National  Park 
and  vicinity,  Arizona  and  a discussion  of  vertebrate  fossils  of  the  southwestern  Upper  Triassic.  29-64.  In 
lucas,  s.  G.  and  hunt,  a.  p.  (eds).  Dawn  of  the  age  of  dinosaurs  in  the  American  Southwest.  New  Mexico 
Museum  of  Natural  History,  Albuquerque,  414  pp. 

olsen,  p.  e.  1989a.  Stop  9.1  : St  Mary’s  Bay,  Rossway,  NS.  135-137.  In  olsen,  p.  e.,  schlische,  r.  w.  and  gore, 
p.  J.  w.  (eds).  Tectonic , depositional  and  paleoecological  history  of  early  Mesozoic  rift  basins,  eastern  North 
America.  American  Geophysical  Union,  Washington,  174  pp. 

19896.  Stop  11.1:  Carrs  Brook  near  Lower  Economy.  149-150.  In  olsen,  p.  e.,  schlische,  r.  w.  and  gore, 
p.  J.  w.  (eds).  Tectonic,  depositional  and  paleoecological  history  of  early  Mesozoic  rift  basins , eastern  North 
America.  American  Geophysical  Union,  Washington,  174  pp. 

— and  sues,  h.-d.  1986.  Correlation  of  continental  Late  Triassic  and  Early  Jurassic  sediments  and  patterns 
of  the  Triassic-Jurassic  tetrapod  transition.  321-351.  In  padian,  k.  (ed.).  Beginning  of  the  age  of  dinosaurs: 
faunal  change  across  the  Triassic-Jurassic  boundary.  Cambridge  University  Press,  Cambridge,  378  pp. 

Schaeffer,  b.  1967.  Late  Triassic  fishes  from  the  western  United  States.  Bulletin  of  the  American  Museum  of 
Natural  History.  135,  287-342. 

— and  Gregory,  j.  t.  1961.  Coelacanth  fishes  from  the  continental  Triassic  of  the  western  United  States. 
American  Museum  Novitates,  2036,  1-18. 

schroeder.  b.  1982.  Entwicklung  des  Sedimentbeckens  und  Stratigraphie  der  klassischen  Germanischen  Trias. 
Geologische  Rundschau,  71,  783-794. 


HUNT  AND  LUCAS:  NON-MARINE  UPPER  TRIASSIC 


501 


shelton,  s.  v.  1984.  Parasuchid  reptiles  from  the  Triassic  Dockum  Group  of  West  Texas.  Unpublished  M.Sc. 
thesis,  Texas  Tech  University. 

toepelman,  w.  C.  1916.  Phytosaur  remains  from  New  Mexico.  Bulletin  of  the  University  of  Oklahoma  103, 
26-28. 

trauth,  f.  1948.  Geologie  des  Kalkalpenbereiches  der  zweiten  Wiener  Hochquellenleitung.  Abhandlungen  der 
Geologie  B un de sans t alt,  26,  1-99. 

valencio,  d.  a.,  mendia,  j.  e.  and  vilas,  J.  f.  1975.  Paleomagnetism  and  K-Ar  ages  of  Triassic  igneous  rocks 
from  the  Ishigualasto-Iscichuca  basin  and  Puesto  Viejo  Formation,  Argentina.  Earth  and  Planetary  Science 
Letters  26,  319-330. 

walker,  a.  d.  1961.  Stagonolepis,  Dasygnathus  and  their  allies.  Philosophical  Transactions  of  the  Royal  Society 
of  London,  Series  B,  248,  103-204. 

— 1968.  Protosuchus , Proterochampsa  and  the  origin  of  phytosaurs  and  crocodiles.  Geological  Magazine, 

105,  1-14. 

westphal,  f.  1976.  Phytosauria.  99-120.  In  charig,  a.  j.,  krebs,  b.,  sues,  h.-d.  and  westphal,  f.  Thecodontia : 
Handbuch  der  Palaeoherpeto/ogie  Teil  13.  Gustav  Fischer  Verlag,  Stuttgart,  136  pp. 
williston,  s.  w.  1904.  Notice  of  some  new  reptiles  from  the  Upper  Trias  of  Wyoming.  Journal  of  Geology  12, 


688-697. 


Typescript  received  31  January  1990 
Typescript  accepted  5 April  1990 


ADRIAN  P.  HUNT  AND  SPENCER  G.  LUCAS 

New  Mexico  Museum  of  Natural  History, 
Post  Office  7010,  Albuquerque, 

New  Mexico  87194-7010,  USA 


I 


NOTES  FOR  AUTHORS 

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m 


Palaeontology 

VOLUME  34  ■ PART  2 


;(x 

77 


CONTENTS 


A spider  and  other  arachnids  from  the  Devonian  of  New  York, 
and  reinterpretations  of  Devonian  Araneae 

P.  A.  SELDEN,  W.  A.  SHEAR  and  P.  M.  BONAMO  241 

Ordovician  graptolites  from  the  early  Hunneberg  of  southern 
Scandinavia 

K.  LINDHOLM  ’283 

Trilobites  from  the  Ordovician  of  Portugal 

M.  ROMANO  329 

Cambroclaves  and  paracarinachitids,  early  skeletal  problematica 
from  the  Lower  Cambrian  of  South  China 

S.  CON  WAY  MORRIS  and  CHEN  MENGE  357 

The  ostracoderm  Phialaspis  from  the  Lower  Devonian  of  the 
Welsh  Borderland  and  South  Wales 

P.  R.  TARRANT  399 

The  rhynchonellide  brachiopod  Eocoelia  from  the  Upper 
Llandovery  of  Ireland  and  Scotland 

E.  N.  DOYLE,  A.  N.  HOEY  and  D.  A.  T.  HARPER  439 

The  role  of  predation  in  the  evolution  of  cementation  in  bivalves 

E.  M.  HARPER  455 

Morphologic  patterns  of  diversification:  examples  from  trilobites 
M.  FOOTE  461 

The  Paleorhinus  biochron  and  the  correlation  of  the  non-marine 
Upper  Triassic  of  Pangaea 

a.  p.  hunt  and  s.  G.  LUCAS  487 


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