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HARVARD UNIVERSITY
e
Library of the

Museum of

Comparative Zoology

VOLUME 80, NUMBER 313 SEPTEMBER 8, 1981

Paleontology, Taphonomy and Paleoecology

of the
Palmarito Formation (Permian of Venezuela)

by
Peter R. Hoover

Paleontological Research Institution
1259 Trumansburg Road
Ithaca, New York, 14850 U.S.A.

Library of Congress Card Number; 81-83795

Printed in the United States of America
Allen Press, Inc.
Lawrence, KS 66044 U.S.A.

CONTENTS

BAUS ETA Ctra ss oetay be veze sarees sual says, si'ie's 6/3 ar nten gp epiva'a al sishccehavetr'e lereteveys
NOMEN gooocsssonconase coondaDOOOODONNOOdOGODOOUODEDNN
ES OV ARTETIGIS: 4g foo os sabe ona nee pepcodmare sos onas Du
LTMOCMEHOM epascesoobocdoe boopapepanD ese pdeboucontuDEor
The Palmarito Formation
IRECIONAIESC LUMO amc trrerracre etter Pelevereierletalete aie svave cersioreieverskeiere
EW SCONIGA BS CUEN Garay ccckeresearieretetereeiecisherersueieseueccusinne Co eerateiete
Biostratigraphic) Correlation’ 9-2. <<<. <2-- 0+ 3-0 a=
Lithic and Faunal Analysis
ITTOCMCTON “eecodgococaapneeusncoboodoDonnanEononoec[
ithic Description) Mechniques) see cci-lllse nee ae clio
BAUM AL MIE SUS sae epec crags 7a ene csc arc ereie eferelaiare/eyaveterstat ays ie, or cyexayeve
MAP NOMOM VaMeerct iret conererorererelololorelelciesotstate evscerers.cniererate
PARTIEOWSY woodcdeeacooedsdnaanoopnnaonedsaadeaeet
Collecting Localities
MEOGALI ty) Tay svesesare-sysicytistai sveresiedisiais spew ee) sisieidierevs simvesaee is
IL@VCANNT 2” Sipe cs Coe URS OO OOOO Taine ner areas
| Lrovers [ais he Staemte SoS One mid ee Ce a icc eae oer reo
MBO Pali ty 4 totes cta:c/ocsyniars suey anche Sree sais we sree sseyero areas
MEO CALL 750 Nevetos re. 3: x7x tsi ceo ecetesarehshavessysqsiesov co ei vv otevs Sats zisrare
I LOVATO, On oa eneas soopopode oy an oemaUoomoneos soemnaa ae
MB OC ALLEY Aimer raee trea aer hc raens oontish Sakeieserene cect ee lots are
MBOC ALLY A Ome ester ysr saeco fete acues susp sistaysteiah sy aversnwe crepe eiayare wicteeNO
MBO CALEY) ILO) ares: axe where rescinvwtes sis cavsvoisrs: sxassievele oeiarsaievars eevee eis
ME QC ALA ya ete ces areca tages ayes es aise Ysieieseses wos E aie ee wid eases
MBO Alby AUS ie cece states cassatescinve. ov oreinpetek ari eucledanmncavs: axes Skat aevereene
Depositional/Environments) 2c} -aceieme cise ele ceree ee
Organism/Substrate Relationships ....................----+
REEMA DUR ALLO bar nescecysTsictcke nesters etter elernys ie eres taeia ernie ayes ss
Samplin ge ficiencysINdexa mace secession eiiey=
Introduction to Systematic Paleontology

Ehilosophicali€onsiderations’ @2.0--52- sss 062022626 one

Format

TMETMINOLO SY ers v/s tate ole stersrs stains olocie se oma s «Mieke Siolonie sie s¢ 38
hy peyREPOsitomles! crimes ercieiemnrecieinerriericre 39
Measurementsieeccrresser octane en eet orci ae oe 39

Brachiopod Systematic Paleontology

Hamily;CraniidaesMenke pane eee ee eee eee ere 39
Family Schizophoriidae Schuchert and LeVene ........... 40
EamilyDerbyiidae'Stehlin=-m--sceeenece etre eee cee 41
RamilyiMeekellidae)Stehlig --ssacaeeriicecein cece iiie ie taere 47
Family Rugosochonetidae Muir-Wood ..................-. 49
Family Aulostegidae Muir-Wood and Cooper ............. 55
Family Cooperinidae Pajaud .....................2.0005 57
Family Rhamnariidae Muir-Wood and Cooper ............ 59
Family sMarginiferidae:Stebli) ease cee eerie eer 62
Family Paucispiniferidae Muir-Wood and Cooper ......... 66
Family Linoproductidae Stehli ....................0.220. 70
Family Retariidae Muir-Wood and Cooper ............... 72
Family Echinoconchidae Stehli .........................-- 74
HamilyaDictyoclostidae:Steblin wasencne saci cetera 74
Family Lyttoniidae)Waagen) <.--.-4.-.-. sees = ose ene 82
Family Pontisiidae Cooper and Grant .................... 84
Family uncertain (Rhynchonellacea) ..................... 87
Family sRetziidaeiwaagent a eeree-ta cece ae ceenen 88
Kamily; AthyrididaesMc@oyin.-e 4. aceecce ace ceases 93
Family Ambocoeliidae George ......................005 96
RamilysBlythidaeybredeniksmaseeiceecceeee cee 98
RamilysSpinifendacs kone eee reer eeer nr ticereereteeeere 100
Family Reticulariinidae Cooper and Grant ............... 102
Family Dielasmatidae Schuchert ........................ 104
Family Pseudodielasmatidae Cooper and Grant ........... 105
Family Cryptonellidae Thomson .....................--- 106
ReferencesiCitediiracmemierewicterhierscirerataciciete citer teeter 109
PIAteS 3 oc eisetateere eit yet eee ees See 117
Tn OX: Fares acsrcucrererey corel feteens ouerarcicee tones oy evseavnretcl sere eve eneeetat reno 128

LIST OF ILLUSTRATIONS

Text-figure

ils

Maps showing location of eleven Palmarito Formation

fossil assemblages

. Similarity coefficient matrix for brachiopod genera in

Palmarito Formation fossil assemblages
Dendrogram showing similarities in brachiopod gener-
ic composition among Palmarito Formation fossil
assemblages mermrire iit t either tiie:
Brachiopod occurrences and taphonomic indices in
eleven collecting localities within the Palmarito Forma-
tion
Habitat-type distributions for species and individuals
in Palmarito Formation brachiopod assemblages ...
Permian Ratio for brachiopods, calculated for well-
known localities of marine Permian fossils, plotted
Against latitud clare rene rere artiste yeni aie
Permian Ratio and Sampling Efficiency Index for
nine Palmarito Formation and 35 Road Canyon For-

mation articulate brachiopod assemblages

. Sampling Efficiency Index for Permian articulate

brachiopod assemblages, calculated for well-known
collecting localities, plotted against latitude ........
Shape variation of dorsal valves of four samples of
Cooperina from the Permian of West Texas and

Venezuela

. Comparison of shell form of two population samples

of Echinauris bella Cooper and Grant (1975)

. Scattergrams of dimensions of two population sam-

ples of Hustedia hyporhachis n. sp. from Venezuela
and one population sample of Hustedia consuta

Cooper and Grant (1976b) from West Texas

Page

Bee PN Mea va Ter oper ove seusishet ibe desiete ole foldout inside back cover

Ww
tr

Table

LIST OF TABLES

. Occurrences of brachiopod genera in Palmarito For-

mation fossil assemblages

. Comparison of brachiopod generic composition of

the Palmarito Formation and of selected Permian

biostratigraphic units in the West Texas region

. Comparison of brachiopod generic composition of

Palmarito Formation fossil assemblages and (or) as-

semblage groups, with West Texas stratigraphic

. Genera and families of Arnold collection Palmarito

Formation brachiopods identified by H. M. Muir-
Wood and P. R. Hoover

. Results of rock constituent analyses of Venezuelan

marine Permian rocks containing appreciable num-

bers of silicified fossils

. Habitat-type classification of Palmarito Formation

brachiopod genera
Familial affinities of Palmarito Formation brachio-
POU BENET Aa Aaj cree. ces sorts ev euesseesoiet ete elle eee
Permian Ratio and Sampling Efficiency Index of Pal-
marito Formation articulate brachiopod assem-
EV Coh SEomnnCa Doma e Oe mOnnSacno Amano SDS a0o0
Measurements of dorsal valves of Cooperina inex-
pectata Termier, Termier and Pajaud (1966) from
locality 6, Palmarito Formation ...................
Statistics calculated from measurements of dorsal

valves of two species of Cooperina Termier, Termier

and Pajaud (1966)

Page

60-61

Bue (F/G MUS. COMP. ZOOL,

LIBRARY

‘TOLUME 80, NUMBER 313 SEPTEMBER 8, 1981

Paleontology, Taphonomy and Paleoecology

of the

Palmarito Formation (Permian of Venezuela)

by
Peter R. Hoover

PALEONTOLOGICAL RESEARCH INSTITUTION

Officers
IPRESTDBNIT. | Vie cls cteatenca acne eit ooo old Se ent onan ote aes orate JOHN POJETA, JR.
VICE-PRESIDENT Ds potest ce ee el ce ss ok arson a ayn cch oe rolls oe ee eerie Bruce M. BELL
SECRETARY Ath EOS NAUGAY Sisal ea aeic pes hime any AOR aerate PHILIP C. WAKELEY
TREASURERO Na) fe ere ee crete chee auieT ae elsTe Se oem te nero Micketae E. JOSEPH FARRELL
ASSISTANT UNREASURER octets: cm foe opie cio p eyasinciansccns sie a trap aieele JOHN L. CISNE
DIRECTORY 310 can ora eer eae ars hans sisi vik er Me ue eer ae eke) oan Oe eee ee PETER R. HOOVER
DIRECTORVUEMERITUS. ots. cuties oxac sieekee ie taecine ene KATHERINE V. W. PALMER
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PALEONTOLOGY, TAPHONOMY AND PALEOECOLOGY OF THE
PALMARITO FORMATION (PERMIAN OF VENEZUELA)

By
PETER R. HOOVER

Paleontological Research Institution
1259 Trumansburg Road
Ithaca, New York 14850 USA

ABSTRACT

The Palmarito Formation of the Venezuelan Mérida Andes is late Early and early Late Permian (Roadian—Wordian) in age,
and contains a well-preserved, diverse fauna including many forms of a distinctly Tethyan aspect. Its carbonate sediments were
deposited in a variety of marine, warm-water shelf environments, under variable energy conditions. Values of both diversity
(as Stehli’s Permian Ratio) and sampling efficiency (as his Sampling Efficiency Index) for Permian brachiopods are enhanced by
bulk collections of rock containing silicified fossils. On a global scale, the observed southward decline in sampling efficiency is
chiefly a result of less intensive study of faunas in southern regions. No parameter relating substrate character to faunal
composition was found. The brachiopod fossil fauna includes 32 genera of which three (Stauromata, Costicrura, and Anapty-
chius) are new, 44 species of which 12 (Derbyia auriplexa, Derbyia deltauriculata, Dyoros acanthopelix, Stauromata esoterica,
Xenosteges minusculus, Rugatia intermedia, Spinifrons grandicosta, Collemataria venezuelensis, Hustedia hyporhachis, Cos-
ticrura minuta, Aneuthelasma globosum and Anaptychius minutus) are new, and two subspecies of previously described species,
one of which (Peniculauris subcostata latinamericana) is new. Internal structures of a new chonetacean brachiopod genus are
developed by application of new serial peel reconstruction techniques.

RESUMEN

La Formacion Palmarito de los Andes Meridenos de Venezuela es de edad Permico Inferior alto a Superior bajo (Road-
ian—Wordian), y contiene una fauna diversa y bien preservada, incluyendo muchas formas de un aspecto distintivamente Teth-
iano. Sus sedimentos calcareos fueron depositados en una variedad de ambientes marinos, de aguas calidas y someras, debajo
de varios condiciones energéticas. Los valores de diversidad (expresada como la *‘Permian Ratio’’ de Stehli) y de la eficiencia
de muestreo (expresada como su ‘Sampling Efficiency Index’’) fueron mejorados para los braquidpodos Pérmicos por colec-
ciones masivas de rocas que contienen fosiles silicificados. En una escala global, la declinacion que se observa hacia el sur en
la eficiéncia de muestreo se debe principalmente al estudia menos intensivo de faunas en las regiones septentrionales. No se ha
podido hallar ningun parametro que relacione el caracter fino del sustrato a la composicion faunistica. La fauna fosil de bra-
quiopodos incluye 32 géneros, de los cuales tres (Stauromata, Costicrura y Anaptychius) son nuevas, 44 especies de las cuales
12 (Derbyia auriplexa, Derbyia deltauriculata, Dyoros acanthopelix, Stauromata esoterica, Xenosteges minusculus, Rugatia
intermedia, Spinifrons grandicosta, Collemataria venezuelensis, Hustedia hyporhachis, Costicrura minuta, Aneuthelasma glo-
bosum y Anaptychius minutus) son nuevas, y dos subespecies de especies previamente descriptas, de las cuales una ( Peniculauris
subcostata latinamericana) es nueva. La estructura interna de un nuevo geénero de braquidpodos (Chonetacea) es descubierta
por la aplicacion de una nueva técnica por laminas seriadas.

ACKNOWLEDGMENTS

Financial and logistic aid from the following
sources, without which this dissertation could not
have been completed, is gratefully acknowledged:
Ministerio de Energia (Direccion de Geologia), Re-
public of Venezuela; Geological Society of America
Penrose Bequest Research Grants 1566-72, 1685-73,
and 1804-74; Sigma Xi Grants in Aid of Research in
1973 and 1974; National Science Foundation Research
Grants GA16827 and GA26210 (awarded to F. G. Steh-
li); Smithsonian Institution Research Foundation Pre-
doctoral Fellowship (1974-1975).

For expediting and aiding my field work from their
positions in the Ministerio de Energia, in Caracas and
in Mérida, I am indebted to the following persons:

Dra. Cecilia Martin, Dr. Alirio Bellizzia, Dr. R. Gar-
cia-Jarpa, and Dr. Peter Motiscka. I would like to ac-
knowledge the friendship and unfailing help which I
received from many of the people of Venezuela, es-
pecially Don Luis Maria Molina y Vega, of Canagua,
Estado Mérida. I would also like to thank those who
helped me in the field: Rito Altube, Clodomiro Garcia,
Alfonso Mendes, Domingo Molina, Leovijildo Molina,
Vicente Molina, Antonio Mora, Pastor Mora, Silberio
Mora, Antonio Rondon, Abundio Rivas and Jesus
Uzcategul.

I also wish to thank Rex Doescher (Dept. of Paleo-
biology, USNMNH, Smithsonian Institution, Wash-
ington, DC, U.S. A.) for his help in locating necessary
references.

6 BULLETIN 313

Thanks are due to the hard-working paleontologists
who took their time to identify non-brachiopod ma-
terial from the Palmarito Formation: Olgerts L. Kark-
lins (OLK), of the U.S. Geological Survey, Washing-
ton, D.C., identified bryozoans, W. M. Furnish
(WMEF), B. F. Glenister (BFG), and C. S. Lee (CSL),
of the University of Iowa, Iowa City, Iowa, identified
cephalopods; the late A. G. Smith (AGS), of the Cal-
ifornia Academy of Sciences, San Francisco, Califor-
nia identified chitons; C. T. Scrutton (CTS), of New-
castle-upon-Tyne, England identified corals; the late
J. J. Burke (JJB), of the Cleveland Museum of Natural
History, Cleveland, Ohio, identified crinoids; Porter
M. Kier (PMK), of the National Museum of Natural
History, Washington, D.C. identified echinoids; Ray-
mond C. Douglass (RCD), of the U.S. Geological Sur-
vey, Washington, D.C., identified foraminifera; Ellis
L. Yochelson (ELY), of the U.S. Geological Survey,
Washington, D.C. identified gastropods; I. G. Sohn
(IGS), of the U.S. Geological Survey, Washington,
D.C., identified ostracods; N. D. Newell (NDN), of
the American Museum of Natural History, New York,
New York identified pelecypods; J. K. Rigby (JKR),
of Brigham Young University, Provo, Utah identified
sponges; C. K. Chamberlain (CKC), now of the Cities
Service Co., Denver, Colorado, identified trilobites.
Drs. Peter Jung and Rene Panchaud of the Naturhis-
torisches Museum of Basel, Switzerland kindly pro-
vided me with casts of important type materials. Dr.
J. Howard, of the Skidaway Institute of Oceanogra-
phy, Savannah, Georgia, kindly provided X-radio-
graphs of rock samples.

I am indebted to P. O. Banks, L. Burkley, S.
Franks, J. Helwig, G. Klar, P. McCall, and J. Murphy
of Case Western Reserve University, Cleveland,
Ohio, and R. G. Shagam of the University of the Ne-
gev, Beer-Sheva, Israel, for stimulating discussions on
many aspects of Central and South American geolog-
ical problems.

The ‘*‘Take a Brachiopod to Lunch”’ bunch of the
National Museum of Natural History (Department of
Paleobiology) and the United States Geological Sur-
vey (Paleontology and Stratigraphy Branch), including
G. A. Cooper, J. T. Dutro, Jr., M. Gordon, R. E.
Grant, R. B. Neuman, and B. R. Wardlaw are here
collectively thanked for many intellectually stimulat-
ing and (or) provoking discussions.

Drs. F. G. Stehli and R. E. Grant acted as co-ad-
visors through the course of this study, and helped
knead the manuscript drafts into professionally read-
able thesis form. Drs. R. E. Grant and J. W. Wells
reviewed the revised manuscript. I would like to ex-
tend my profound thanks to these individuals for their
aid and comments.

This work is dedicated to my wife Caroline, for re-
maining sympathetic to me and my chosen profession.

INTRODUCTION

For several years paleontologists and biologists
have been interested in the global diversity patterns
of marine organisms, particularly those that can be
used in interpretation of the fossil record (Stehli, 1957;
Fischer, 1960; Stehli et al., 1969; Waterhouse and
Bonham-Carter, 1975). Stehli (1971) has related lati-
tudinal taxonomic diversity gradients to the distribu-
tion of families of thermally-tolerant cosmopolitan,
and thermally-sensitive endemic Permian articulate
brachiopods. He found measured diversity to be high-
ly variable, and devised a statistic, the Permian Ratio,
that minimized diversity variations caused by inade-
quate sampling. This ratio is defined as:

= C
Cc

where > = the total number of brachiopod families
identified, and C = the number of globally cosmopol-
itan families identified at that locality. By making the
number of cosmopolitan forms less significant, the sta-
tistic increases the significance of the endemic (and
thermally-sensitive) forms recovered. Permian Ratio
values (see Text-fig. 6), plotted against latitude, in-
crease from the poles toward a maximum near, but
north of the present Equator. Some low-latitude sta-
tions have anomalously low Permian Ratio values.
Stehli also observed that sampling efficiency, as mea-
sured by the percentage of possible global cosmopol-
itan families recovered at any locality, declined toward
the south from about 30° North latitude. A potentially
fruitful line of investigation was to try to determine,
through the study of new collections, if anomalously
low Permian Ratio values at a selected equatorial sta-
tion were due to sampling inadequacy, and, if so, in
what ways sampling could be improved. I also hoped
to explain why otherwise cosmopolitan families were
missing.

Central and South America are comparative un-
knowns, in terms of Permian brachiopods. South of
Mexico, well-documented Permian brachiopod faunas
of Tethyan aspect are known only from Guatemala
and from the Titicaca region of Peru and Bolivia. For-
mal description and illustration are necessary prere-
quisities for use of a fauna in diversity studies, as they
enable an investigator to verify taxonomic assign-
ments for himself. Between Guatemala, at 16° North
latitude, and Peru, at 7° South latitude, numerous fau-
nas had been reported in faunal lists, but none had
been comprehensively treated. When the opportunity
for study there arose, I undertook a rigorous system-

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 7

Mérida
State

Qda

El Palmar

ee
approx. | km

watercourse mule trail

V5 1°21'w

settlement O

collecting @
locality

to Mucuchachi
weveeeeeP Mucuchachi

Text-figure 1—Maps showing location of the eleven Palmarito Formation fossil assemblages collected for this study.

atic, taphonomic and paleoecologic survey of the fos-
sils, especially the brachiopods, of the Permian Pal-
marito Formation of the southwestern Venezuelan
Andes, at approximately 8° North latitude.

During the rainy season—June and July—of 1971 a

reconnaissance expedition to the type area of the Pal-
marito Formation was undertaken. This area is located
about 250 kilometers south of the city of Mérida, Ven-
ezuela (Text-fig. 1), and at that time was reached by
jeep, mule and foot from that city. Samples from as

8 BULLETIN 313

many fossiliferous exposures as possible were taken:
the main purpose was to find those exposures that
promised optimal sampling, by means of collection of
silicified fossils. Forty-one localities sampled during
that field season yielded about 500 kilograms of rock
and fossils that was returned to the United States for
study. During the remainder of that year and the two
following, specimens were prepared, and the most
promising localities earmarked for re-collection. The
next field season—March through April, 1973—came
at the end of a protracted dry season in Venezuela,
making access to localities easier than it had been pre-
viously, and many of the logistic hardships encoun-
tered in 1971 were eased. Nine of the original 41 lo-
calities were re-sampled in bulk: several additional
samples that looked promising were taken as well.
Approximately 1300 kilograms of fossil-bearing matrix
from the Mérida Andes was returned from the 1973
season. No mapping was undertaken, because field
time was limited, and because preliminary mapping
had already been done by agencies of the Venezuelan
government.

The results of the study are several. The brachiopod
specimens used in preparation of Arnold’s 1966 faunal
list for the Palmarito Formation were re-examined. It
was determined that the brachiopod diversity had been
overestimated and that many identifications not only
were incorrect but also biostratigraphically mislead-
ing. Examination of Arnold’s collections, in combi-
nation with those made by the author, showed the unit
to be largely of latest Early Permian (sensu Grant and
Cooper, 1973) rather than Permocarboniferous age, in
the type area.

Examination of all available fossil assemblages re-
covered from the author’s collections showed that the
Palmarito fauna is truly Tethyan in aspect and that its
previously reported temperate character was probably
largely a result of the comparative rarity of the hard
substrates necessary for the attachment of many en-
demic Tethyan brachiopod forms. The decline in Sam-
pling Efficiency Index southward from about 30°
North was determined to be in great part a result of
less intensive study of those faunas, but no definitive
test of causal relationships could be made. Attempts
to find a quantitatively measurable parameter that
could relate substrate character and faunal composi-
tion were unsuccessful, but one character tested—silt/
clay ratio of insoluble residues—may be an indicator
of energy regime (Hoover, 1976b). The Palmarito as-
semblages sampled are inferred to have been depos-
ited in a variety of warm-water shelf environments,
from beach or bar to level bottom below wave base.

The entire fauna is reported in the form of faunal

lists, while the brachiopod fauna is identified, de-
scribed and figured, and is discussed in terms of its
biostratigraphic, paleoecologic, taphonomic and pa-
leogeographic significance. The brachiopod fauna in-
cludes 32 genera of which three are new, 44 species
of which 12 are new and 2 subspecies of previously
existing species, one of which is new.

THE PALMARITO FORMATION

REGIONAL SETTING

It is generally agreed that late Paleozoic marine sed-
iments in the Western Hemisphere were deposited in
a geosynclinal basin or series of basins. The form of
this trough, however, is unclear, although several hy-
potheses have been proposed. These may be separated
into two groups, whose basic difference lies in the
disposition of the present Caribbean Islands. In Perm-
ian continental reconstructions, these troublesome
fragments, for which no Late Paleozoic paleomagnetic
data are available, most commonly have been placed
within a reduced Caribbean Sea. For example, the hy-
potheses of Carey (1958) and Freeland and Dietz
(1971) place most of Mexico in the position of the pres-
ent Gulf of Mexico in pre-drift time, and rotate the
pre-Mesozoic Yucatan and Central American base-
ment blocks to produce a Late Paleozoic continental
mass in the Gulf Region. In the last decade, another
family of hypotheses has arisen that seem to require
less strain on both imagination and the laws of physics.
Hamilton (1966), Walper and Rowett (1972) and van
der Voo et al. (1976), assume an opposite sense of
rotation of the region which appears as an overlap in
the ‘Bullard Fit’’ (Bullard et al., 1965), and place the
resultant southern tip of Mexico off the west coast of
South America. This produces a more intimate pre-
Mesozoic connection of the southern Appalachian,
Ouachita, Mexican-Central American and northern
Andean geosynclinal belts, which in turn helps to ex-
plain the great faunal similarity of the Palmarito and
its stratigraphic equivalents in North America. Paleo-
magnetic studies necessary to test the sense of rotation
of the critical Central American and Caribbean frag-
ments have not been made, as rocks of suitable age
and type have not been examined from many parts of
that region (Hicken er al., 1972). Itis hoped that future
paleomagnetic studies, in combination with pertinent
Upper Paleozoic faunal studies such as this one, will
provide data that can be used in such a test.

Permocarboniferous sediments were deposited over
a great area of Central and South America, but this
time was not one of extensive oceanic development,

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 9

relative to the Early Paleozoic. In addition, known and
studied exposures of marine Upper Paleozoic rocks in
the area are rather limited. Many parts of the region
have been affected by severe diastrophism since
Permian time, so that much Upper Paleozoic sedi-
mentary section has been removed by uplift and con-
sequent erosion, or faulting. Great thicknesses of fos-
siliferous strata have been metamorphosed to the
degree that fossils can no longer be recognized and
identified. Without such aids, the depositional age of
the units cannot be determined directly.

Many known fossil localities in the region are not
fully exploited, in part due to poor accessibility, thick
vegetative cover, high degree of slope and rapid
weathering. Until recently, little detailed geological
investigation had been carried out in many of these
areas, except in connection with petroleum company
operations. Recent literature syntheses and the work
of national geological surveys or ministries of mines,
in combination with the International Stratigraphic
Lexicon project, have aided in the resolution of many
of these problems.

Though on present latitudinal coordinates, Texas
lies north of the Equator and far from exposures of
the Palmarito, it is a proper place to begin a more
detailed regional discussion. The Permian strata of
West Texas and adjacent New Mexico have been stud-
ied assiduously since Shumard (1858, 1859) made his
original reports. Most portions of the diverse fauna
have been reported in monographic form. The bra-
chiopods alone have been treated in four monographic
studies (Girty, 1909; R. E. King, 1931; Stehli, 1954;
Cooper and Grant, 1972, 1974, 1975, 1976a, 1976b,
1977). Because of this concentrated and detailed
study, and the vast amount of comparative material
available (over 72 tons of matrix collected and pro-
cessed since 1939 at the USNM alone), the West Tex-
as sections have become a Western Hemisphere stan-
dard for both faunal comparison and stratigraphic
correlation in the Lower, and lower Upper Permian.
Stratigraphic terminology used in later discussions fol-
lows that of Cooper and Grant (1972).

Palmarito-equivalent strata are known from many
areas in Mexico (Lopez-Ramos, 1969), along the
course of the Paleozoic geosyncline that follows the
axis of that country. Lopez-Ramos reported 28 studied
marine Permian localities in Mexico, extending from
Sonora in the north to Chiapas in the south. The sed-
imentary histories of the exposures differ, tending to
support the separation of these areas during the Late
Paleozoic.

Two sections in Mexico have received rigorous fau-
nal treatment. Cloud (in R. E. King et al., 1944) stud-

ied the exposures at Las Delicias, Coahuila, where the
section consists of limestones, mudstones, sandstones
and conglomerates, and spans the Permian from Wolf-
campian to apparent Ochoan-equivalents. Over 3000
m of section are exposed. Cooper et al. (1953) ex-
amined the marine Permian exposures at E] Antimonio
in western Sonora. Strata of Word age exposed there
are about 500 m thick.

The basinal complex in Mexico continues through
Guatemala and British Honduras and may extend into
the Caribbean along the trend of the Cayman Ridge
and Bartlett Trough (Dengo and Bohnenberger, 1969).
Although these southernmost Permian marine expo-
sures in Central America have been known since the
pioneer studies of Sapper (1937), relatively few have
been investigated paleontologically. Stehli and Grant
(1970) reported a diverse brachiopod fauna from the
Chochal Limestone, of the Department of Huehuete-
nango, Guatemala, that shows close similarities to the
Palmarito fauna. This unit, now placed within the re-
gionally more applicable Santa Rosa Group (Clemons
et al., 1974) has been correlated with the Leonard
Formation of the West Texas area, on the basis of
brachiopods (Stehli and Grant, 1970), fusulinids (Hen-
best, in Roberts and Irving, 1957; Kling, 1960) and
ammonoids (Glenister, pers. comm., 1974). Hoffstet-
ter (1960) reported a Permian fauna from the Macal
Series of the Santa Rosa Group of Belize, but pre-
sented only a faunal list. No Upper Paleozoic marine
rocks have been reported from the Caribbean virga-
tion. Following the apparent structural trend into the
South American continent, the first rocks of this char-
acter encountered are those of the Palmarito Forma-
tion. The Palmarito, like many Permian Tethyan units
in the Western Hemisphere, consists of a predomi-
nantly clastic, terrigenously-influenced lower shaly
member and a predominantly marine upper limestone
member, which ranges in age from Late Leonardian
to Early Guadalupian. Rocks of similar lithic character
from the Sierra de Perija in Colombia (Trumpy, 1943),
contain a fauna of sponges, foraminifera, crinoid re-
mains, brachiopods, gastropods and cephalopods
(Burgl, 1973). To the writer’s knowledge only the fo-
raminifera (Miller and Williams, 1945) and cephalo-
pods (Thompson and Miller, 1949) of this area have
been systematically treated in the literature. Expo-
sures of questionable Permian age have been reported
from other areas within Colombia (Burgl, 1973; Stehli,
pers. comm., 1974), but none has yielded significant
faunal data.

Upper Paleozoic marine rocks of the Macuma For-
mation are known in one outcrop and one well in the
Cutucu Mountains south of Quito, Ecuador. A fauna

10 BULLETIN 313

of Pennsylvanian age including brachiopods, bryozo-
ans, and crinoid remains was recovered from the lower
part of the unit (Dozy, in Tschopp, 1956) and two
Pennsylvanian foraminifera were recovered from the
lower part of the thicker upper member (Baggelaar in
Tschopp, 1953). The uppermost 150-200 m of the unit
has yielded a brachiopod-bryozoan fauna to which
Goldschmid (in Tschopp, 1953) assigned a latest Penn-
sylvanian to Early Permian age. Stehli (pers. comm.,
1974) has mentioned the existence of Permian red beds
in Ecuador, but no other marine strata are known.

The Upper Paleozoic section is relatively complete
in Peru. Mississippian, Pennsylvanian and Permian
strata have been identified (Newell, Chronic ef al.,
1953) but only the Pennsylvanian and Permian are de-
monstrably marine. Mississippian strata previously re-
ported (Murphy in Megard ef al., 1971) as marine,
have, on reconsideration (Murphy, pers. comm.,
1974) been assigned to the Pennsylvanian. The Penn-
sylvanian marine strata are equivalent in age to the
Itaituba Formation of Brazil.

The Copacabana Group in Peru as well as in much
of Bolivia and adjacent Argentina and Chile, has pre-
viously been considered equivalent in age to some
lower portions of the Palmarito (Newell, Chronic et
al., 1953; Arnold, 1966).

Outside the above areas, the record of holomarine
Permian in South America is poor. Between 50° and
52° South latitude, in the Madre de Dios Archipelago
of Chile, fusulinids that indicate an age ranging up into
the Permian have been recovered from a thick (ca.
5000 m) series of limestones (Cecioni, 1956; Douglass
and Nestell, 1976). Cecioni reported the presence of
a rich and well-preserved fauna in addition to the fo-
raminifera, but included no descriptions or illustra-
tions. Meyerhoff (1970) considered this unit to docu-
ment deposition in warm water and thus to be an
extension of the Permian Tethyan belt. Such a con-
clusion appears unwarranted on the basis of fusulinid
evidence alone, as fusulinids themselves are not in-
dicators of warm-water conditions (Ross, 1967; Dun-
bar, 1973).

There were, in addition to the marine deposits in
what might be termed the Upper Paleozoic Andean
geosyncline, other contemporary marine deposits,
within and between the relatively stable cratonic areas
of South America. Local submergences and incursions
at cratonic borders periodically allowed minor sedi-
mentary deposits to accumulate. Itaituba-equivalent
(mid-Pennsylvanian) strata are apparently widespread
in parts of Brazil, Argentina, Paraguay and Uruguay,
but Palmarito-equivalent beds (which do not overlap
with Itaituba-equivalents) are not nearly so ubiqui-

tous. None has been noted in cratonic areas north of
southern Brazil. Parts of the Passa Dois Series of Ar-
gentina contain Permian marine strata (Frakes et al.,
1969) but their associated faunas, closely associated
with glacial deposits, are clearly of Boreal affinities.

Palmarito-equivalent strata are widely but system-
atically distributed in the Western Hemisphere. Pre-
Mesozoic continental configurations may have been
such as to place some now separate localities relative-
ly closer together. It is tempting to think that such pre-
drift configuration hypotheses might be tested using
faunal diversity data, but present analytic refinements
cannot sufficiently reduce the noise level in the data.
The new hypotheses do, however, aid in explanation
of the great similarity in faunal composition found in
many of the faunas within the Western Hemisphere
marine Permian, because their present great latitudinal
spread is most likely a Mesozoic artifact brought about
by continental plate movements.

HISTORICAL SETTING

The first investigator to consider the relatively un-
deformed Paleozoic strata of the Venezuelan Andes
in detail was Christ (1927), who reported on the geo-
logic section exposed along the trail from Mucuchachi
to Santa Barbara de Barinas (Text-fig. 1). Christ di-
vided strata of from Archaean to Tertiary age into six
series. Of these, only three, the Mucupati, Palmarito
and Lomita Series, are pertinent here. Christ sent the
Palmarito Series fossils to the museum at
Basle, Switzerland, where they were studied and later
reported on by Gerth (in Gerth and Krausel, 1931).

Specimens referred to Fusulina and Spirifer were
the only ones described and illustrated, a dubious dis-
tinction which they have, with a single exception
(Hoover, 1975), maintained to the present day. Gerth
(p. 524) recognized the presence of silicified fossils
(“‘teilweise verkieselte Fossilien’’) in the unit, but nev-
er mentioned that these might provide a better sam-
pling of the fossil fauna. He concluded that, on the
basis of correlations with Bolivia and Asia, the Pal-
marito Series could not be younger than Late Carbon-
iferous.

Englemann (1935) cited three more Palmarito local-
ities along the Transandean highway in the state of
Tachira, but contributed nothing further to the stratig-
raphy, lithology or paleontology of the unit. Schuchert
(1935) reviewed work on the unit to date and con-
curred in the view that it was of Late Carboniferous
age. Hedberg and Sass (1937) dedicated a single two-
line sentence to the presence of fusulinids in a lime-
stone in the upper reaches of the Rio Palmar, Zulia

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 11

state. This appears to have been the first mention of
possible Palmarito equivalents in the Sierra de Perija.

In the following year a dispute began which con-
fused the picture of the Venezuelan Upper Paleozoic
for several years. The Palmarito in the type section
was both under- and overlain by coarser-grained red-
dish sedimentary rocks. The only fossils commonly
found in either of these sandy units were in the lime-
stone cobbles that locally formed a basal conglomerate
within the overlying Lomita Series. Fusulinids, com-
mon in these cobbles, may have been the basis for
Christ’s assignment of a questionable Permian age to
the bottom of the Lomita Series. The lithologic simi-
larity of the Mucupati and Lomita Series made the
Palmarito Series easy to identify (the only non-redbed)
in the type area, but also, in this area where strati-
graphically continuous exposures were exceptional, it
encouraged confusion of the sandy units.

This may be what started the controversy over the
age of the Mucupati Series. Kehrer (1938) collected in
the type area of the Palmarito and Mucupati Series in
the 1930’s. During this trip he collected fossils from
‘“‘various localities in the sandstones within Christ’s
Mucupati Series.’’ A poorly preserved molluscan fau-
na indicated to him and to Kehrer, “‘Cretaceous . . .
rather than Devonian age for the Mucupati Series.”
(Kehrer, 1938, p. 50)

Oppenheim (1937) complicated the situation by sup-
porting Kehrer’s age for the Mucupati and renaming
this Cretaceous unit the Sabaneta Group. Christ’s Lo-
mita Series became the “‘Red Formations,” hardly a
distinctive name in that area, and one which happily
has not been repeated in the literature. To these units
he assigned a Lower Jurassic to Cretaceous age. He
had apparently not known the exact details of Keh-
rer’s work, because he based the post-Paleozoic age
of his Sabaneta Group on the absence of diagnostic
Paleozoic marine fossils and on the presence of plant
remains. Ktindig (1938) mentioned Kehrer’s ideas
about the Cretaceous age of the Mucupati Series, “‘in-
officially [sic.] called the Sabaneta Group,”’ but cited
(p. 29) an exposure of the Palmarito Series that
showed transitional contact with his underlying Sa-
baneta Series (=Mucupati of Christ, 1927).

Because no definite locality for Kehrer’s collections
was given, and no lithic data other than that cited
above was available, the problem probably can never
be completely resolved. The existence in such a tec-
tonically complex region as the type area of the Pal-
marito of a fault sliver of a much younger, lithologi-
cally similar unit, surrounded by Sabaneta strata, is a
distinct possibility. Alberding (1956) may have settled
the Mucupati/Sabaneta controversy by suggesting that

the term “‘Mucupati’’ be considered invalid, since in
the literature it consisted of at least two units of dis-
tinct ages, in fault contact. Because it had originally
been considered Devonian (Christ, 1927), and has re-
cently been shown to be of Carboniferous and Permian
(Pierce et al., 1961) as well as Cretaceous (Aguar-
diente and Tomon Formations of Sutton, 1946) age,
its stratigraphic utility was indeed compromised.

Kehrer (1938) presented a suite of fossils from the
Palmarito Series that had been collected along a new
trail between Palmarito and Sabaneta. He inferred that
there was a high probability that a large portion of the
Palmarito in the type area was of Permian age, perhaps
extending down into the Late Carboniferous in its low-
er portions. Kehrer noted the great similarity of the
Sabaneta to the Giron Series (an apparent equivalent
to Christ’s Lomita Series, introduced by Hettner,
1892). He assigned an Early Carboniferous age to the
Sabaneta.

Schaub (1944) mentioned the occurrence of fusulin-
ids of ‘“‘schwagerinoid”’ type in loose blocks of lime-
stone that formed part of the basal conglomerate of
the La Quinta Formation and described them as hav-
ing been derived from the Palmarito Formation. In his
opinion, the wall structure of the fusulinids indicated
Middle Pennsylvanian to Permian age.

The Upper Paleozoic in Venezuela is not confined
to the Mérida Andes. Liddle (1946), in his book on the
geology of Venezuela and Trinidad, included the sec-
ond major review article on the Palmarito. He dis-
cussed in detail work he had done along the Rio Ca-
chiri in the Sierra de Perija (state of Zulia). There he
described a section about 500 m thick, principally mi-
caceous shales and sandstones, with a basal conglom-
erate. The uppermost 17 to 25 m of this section was
reddish-stained dark limestone, containing crinoid co-
lumnals, Rhombopora or Alveolites, and an uniden-
tified spiriferoid brachiopod. He assigned the section
to the “‘Upper Permian”’ and correlated it with the
Palmarito Formation of the Mérida Andes. The age of
this unit is still in question, because the locality is
difficult to pinpoint, and because field relationships in
the Sierra de Perija are far from clear. Gonzales de
Juana (1951) suggested that only the uppermost red-
dish limestone should be attributed to the Palmarito,
and that the rest of the sequence was better referred
to as a Sabaneta equivalent (of Permocarboniferous
age). De Rivero (1956) suggested that the redbeds
might represent the La Quinta Formation, in fault con-
tact with the overlying Palmarito Limestone, as sug-
gested by the presence of limestone blocks in the basal
conglomerate of the redbeds. Hea and Whitman (1960)
also placed this portion within the La Quinta Forma-

tion. Liddle mentioned as indirect evidence of the
presence of Permocarboniferous in the Sierra de Pe-
rija, float containing Dictyoclostus liddlei Harris, in
the Cano del Oeste of the Rio Cachiri, and fusulinids
in the upper reaches of the Cano Pescado, an affluent
of the Rio Palmar. The former is not referable to any
Palmarito dictyoclostid genus, and probably is not of
Permian age. The fusulinids may have been the same
as those mentioned by Hedberg and Sass (1937).

Sutton (1946) discussed the Palmarito of the type
area in the Mérida Andes, and measured the thickness
of the unit as 1800 m. He did not, however, differen-
tiate the Sabaneta from the Palmarito, which explains
the great thickness given.

Thompson and Miller (1949) described fusulinids
and cephalopods from both the Palmarito and apparent
time-equivalent strata in Colombia. These were ap-
parently the same units, though in different localities,
as those described by Trumpy (1943) from Colombia.
Gonzales de Juana (1951) formalized the formational
status of the Palmarito, and designated outcrops of
sparsely fossiliferous dark limestones near the city of
Mérida (state of Mérida) as Palmarito equivalents.
From some of his samples from that area, Sellier de
Civrieux (1951) identified, in association with Para-
fusulina, a species of the foraminiferan Globivalvuli-
na, which he considered most similar to forms from
the Upper Guadalupian of West Texas.

Pierce et al. (1961) discussed eleven marine fossil-
iferous Paleozoic localities from the southeastern sec-
tor of the Mérida Andes. Though most of these were
already in the literature, all were enhanced by the de-
tailed attention given them. Most localities were in
structurally deformed areas, and although the fauna
recovered in any single place was usually smaller than
that in the relatively undeformed type area, the com-
bined faunal listing is both impressive, and suspect.
On the bases of fusulinid and other faunal evidence,
the age of the unit is from mid-Pennsylvanian to early
Late Permian. Measured sections yielded formational
thicknesses from 200 to about 1200 m. The only sec-
tion other than those in the type region from which a
diverse Palmarito fauna was reported was the Carache
area in the state of Trujillo.

Shell and Creole (1964) mentioned the Palmarito
Formation in a long article dealing mainly with older
units in the Mérida Andes. They did not take issue
with previous conclusions about the age or extent of
the Palmarito, but did mention that on the basis of
palynological investigations, the Sabaneta Formation
was largely of Permian age, with only the lower part
of possible Carboniferous age.

Arnold (1966) described the Sabaneta sequence

2 BULLETIN 313

from several localities in the Mérida Andes. He de-
tailed the lithologic characters observed in all sections,
and arrived at age assignments that do not disagree
materially with those of previous investigators. Exten-
sive faunal lists given for three localities are based on
samples taken in connection with the measurement
and detailed description of stratigraphic sections.

Shagam and Hargraves (1970), in an investigation of
Permocarboniferous redbeds (Sabaneta and Mérida
facies) in the Mérida Andes, considered the Sabaneta
to underlie the Palmarito in its entirety, rather than
contacting it diachronously, as had been suggested by
Arnold. This concept was discussed further by Sha-
gam (1972).

Interest in the Palmarito over the last decade has
not been centered on its faunal composition, but rather
on its precise stratigraphic relationships and correla-
tions, as these relate to the Paleozoic and subsequent
development of the Andean region. At present there
are two opposed hypotheses concerning Paleozoic
sedimentation in this region. One, proposed by Arnold
(in Shell and Creole, 1964; Arnold, 1966) suggested
that Paleozoic sedimentation there occurred in two
time periods, separated by a period of uplift, non-de-
position and some deformation. The first of these sed-
imentary cycles he called the Lower Paleozoic cycle,
which included the deposition of the Caparo Forma-
tion and its northern lateral equivalent, the Mucu-
chachi Formation, in Ordovician and early Silurian
time. Unconformably overlying these, the Permocar-
boniferous continental Sabaneta Formation and its lat-
eral shelf facies equivalent, the Palmarito, were de-
posited.

The opposing hypothesis of W. R. Smith (in Shell
and Creole, 1964; see also Shagam, 1968; Martin B.,
1968; Shagam and Hargraves, 1970; Shagam, 1972)
showed a lower Paleozoic sedimentation cycle during
which the Caparo, El Horno and Mireles Formations,
among others, were deposited. This episode was fol-
lowed by emergence during the Devonian and Missis-
sippian. A second Paleozoic sedimentation cycle,
roughly within the same basin, included the Mérida,
Mucuchachi and Sabaneta facies, lateral equivalents
of roughly the same age, overlain by the northern and
southern facies of the Palmarito Formation, with the
intervening basinal facies of Palmarito-equivalent age
missing.

These two models differ mostly in the age assign-
ment of the Mucuchachi Formation, a sparsely fossil-
iferous sequence of shales, phyllites and slates. In the
latter explanation the Palmarito southern facies covers
a longer time span than does the northern, implying
a transgression of the Palmarito marine environment

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 13

from south to north, during Late Pennsylvanian time.
It also shows a short hiatus within the Palmarito sec-
tion in the south, and between the Palmarito and Mé-
rida facies in the north, representing a period of non-
deposition and (or) erosion, near the Pennsylvanian—
Permian boundary.

The concept of the Palmarito Formation has under-
gone remarkably little alteration since Christ’s first
formal description, while the section around it has
been considerably changed. This is probably due to
several causes. The type area of the formation is re-
mote, and few direct observations have been made
since 1927. Fossils are considered to provide an ob-
jective means of determining relative position in a time
scale, and while the Palmarito is replete with well-pre-
served fossils, with two exceptions (Gerth and Krau-
sel, 1931; Hoover, 1975), none have ever been de-
scribed and figured. Thus, the real affinities of the
fossils remain poorly understood. The Palmarito is
lithologically conspicuous, as it is naturally defined by
under- and overlying redbed units. In other areas it is
less distinctive lithologically, but can be recognized
easily when fossils are present. To field geologists
working in the Mérida Andes, recovery of fusulinids
indicates the presence of the Palmarito Formation.
The extrapolation of this philosophy to the other mac-
rofossils found in association with the fusulinids has
led to problems in correlation, especially with the Per-
mocarboniferous units exposed in the Sierra de Perija.
Typical Palmarito shelf faunas have not been reported,
to my knowledge, from the Venezuelan portion of the
Sierra de Perija. That units of a similar age do exist
close by in Colombia has been established by fusulinid
and cephalopod evidence.

BIOSTRATIGRAPHIC CORRELATION

No attempt at biostratigraphic correlation of the Pal-
marito fossil fauna with non-Western Hemisphere
Tethyan Permian faunas is here attempted. The simi-
larity of the Venezuelan forms to those from West
Texas is so striking that more far-reaching correlation
would in essence be a global correlation of West Texas
rather than Venezuelan forms; an exercise of dubious
significance, considering the comprehensive works on
this subject already presented by others (e.g., Cooper
and Grant, 1972; Grant and Cooper, 1973).

The brachiopod fauna of the Palmarito Formation
includes at least 32 genera and 44 species, of which 3
genera, 12 species and a single subspecies are de-
scribed here as new. The names used in classification
of these taxa are drawn from study of the available
literature, but lean heavily on a recent monograph on
the West Texas brachiopods (Cooper and Grant, 1972,

1974, 1975, 1976a, 1976b, 1977). This seems justified
by the following: (1) Grant and Cooper (1973) have
demonstrated the existence of trans-longitudinal ‘‘pro-
vinciality’’ in the Upper Permian: regions within
which correlation is enhanced and between which cor-
relation is difficult. There is no reason to doubt that
such divisions extend lower in the section. (2) The
West Texas sections appear to be the most continuous
and accessible expanse of Permian strata in the West-
ern Hemisphere, and are considered the standard for
the hemispherical marine Permian. (3) The diverse
fauna recovered there during the past hundred or more
years of study can better elucidate age and facies re-
lationships of the Palmarito Formation than can geo-
graphically closer, yet less well understood faunas in
Central and South America, such as the Copacabana
Group of Peru and Bolivia (Newell, Chronic, ef al.,
1953; Samtleben, 1971) and the Chochal of southeast-
ern Mexico, Guatemala and British Honduras (Stehli
and Grant, 1970; Kling, 1960).

Because my study was primarily faunal in emphasis,
sampling localities were selected to (1) lie within the
lithologically-defined boundaries of the Palmarito For-
mation and (2) contain a high concentration of re-
coverable fossils, preferably silicified. Low on the list
of priorities (and probabilities) was knowledge of the
exact stratigraphic position of a sample within a mea-
sured section. The collection area has been mapped
ona small scale, and at least one stratigraphic section
has been competently measured in the vicinity of the
type section (Arnold, 1966), but the mapping is sche-
matic, and the section offers few recognizable land-
marks for use in sample location. The true stratigraph-
ic position of individual samples can rarely be
determined in the field.

Although it has been stressed (Grant and Cooper,
1973) that age determinations should ideally be made
on the basis of the entire preserved fauna, only the
brachiopods are extensively employed here. The bio-
stratigraphic significance of the remainder of the fauna
is dealt with briefly at the end of this section.

As a first step in correlation, the brachiopod genera
of the Palmarito Formation were compared with those
recovered from each of several of the well-defined
stratigraphic units of West Texas. Data for the latter
were derived from Cooper and Grant (1972, 1974,
1975, 1976a, 1976b, 1977) and from collections at the
National Museum of Natural History (Washington,
D.C.). The Otsuka Coefficient* was used as a standard

* The number of items (genera) shared by the two units com-
pared, divided by the square root of the product of the number of
items in each unit.

14 BULLETIN 313

of comparison, because it appears to reduce the bias
inherent in comparing samples of different sizes (for
discussion of the various binary coefficients which
might have been employed, and their attributes, see
Cheetham and Hazel, 1969). The use of the genus as
a standard in this and following comparisons for cor-
relative purposes follows the rationale of Grant and
Cooper (1973, p. 573). The results of the above com-
parison appear in Table 2. This shows that although
all similarity levels are low, the highest level of simi-
larity lies between the Palmarito Formation and the
Road Canyon and Cathedral Mountain Formations of
West Texas.

In Table 1, one can readily appreciate the great dif-
ference in brachiopod generic composition between
Locality 6 and all other Palmarito Formation localities.
This suggested the desirability of determining how
many distinctive generic assemblages of brachiopods
existed within the Palmarito Formation. To do this I
calculated the similarity in generic composition of bra-
chiopod assemblages at sampled localities within the
Palmarito, and then systematically compared these
groups with brachiopod assemblages from finer strati-
graphic subdivisions in the better-known West Texas
region. Again using the Otsuka Coefficient, the genera
recovered at each locality were compared to those
from every other locality, and the results were plotted
as a similarity matrix (Text-fig. 2). While this matrix
contains all the information needed to determine the
degree of similarity among the localities, it lacks visual

Text-figure 2.—Similarity coefficient matrix for brachiopod gen-
era in Palmarito Formation fossil assemblages. Large numbers rep-
resent localities; smaller numbers are Otsuka Coefficient x 100.

Table 1.—Occurrences of brachiopod genera in Palmarito For-
mation fossil assemblages. x = presence; — = absence.

Localities

Genera LQ Bin 4a Se 164 To 8 LOPS

Acosarina x
Anaptychius x
Anemonaria DX x

Aneuthelasma x

Chonetinetes x x x
Cleiothyridina - -—- X =- = = = = = = =
Collemataria x

Composita
Cooperina x
Costicrura x
Derbyia =—= xX X = X
Dyoros x — =
Echinauris ES ax See
Holotricharina x
Hustedia x x x
Kutorginella a a
Meekella - -—- XK K = =
Neophricadothyris xX - =- = = =
Neospirifer XxX - —- X - =
Oligothyrina x x
Paucispinifera x
Peniculauris x x

Petrocrania x

Pontisia x x7 Ds
Ramavectus =
Rugatia X =
Spinifrons - -
Spiriferellina
Stauromata X= =| X =| = KO eee
Texarina x
Xenosteges x

Total Genera 10° 19) 11 a 10 SiS yeni oees

x xX X &X

Di XS Xo OX eX
| | xX X
[Se eoxXerares aos
|

|
x
|
|
x
x
x
x xX X &X

Table 2.—Comparison of brachiopod generic composition of the
Palmarito Formation and of selected Permian biostratigraphic units
in the West Texas region. Values are expressed as Otsuka Coef-
ficient x 100; N = total number of genera included in given bio-
stratigraphic unit.

Palmarito
Forma-
tion, all
localities
[N = 31]
Capitan and Bell Canyon Fms. (Guadalupian) 29
incl. all mbrs. [N = 73]
Cherry Canyon, Getaway & Word Fms., 32
incl. all mbrs. (Lower Guadalupian) [N = 81]
Road Canyon Fm. (Upper Leonardian) 41
[N = 88]
Cathedral Mountain Fm. (Leonardian) 38
[N = 83]
Skinner Ranch, Taylor Ranch, Hueco and Hess Fms. 33

(Upper Wolfcampian) [N = 81]

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 15

-100

Text-figure 3—Dendrogram showing similarities in brachiopod generic composition among Palmarito Formation
fossil assemblages. Figure derived by weighted-pair grouping of similarity coefficient matrix shown in Text-figure 2.

clarity. To overcome this problem, the matrix was
‘clustered,’ using the weighted-pair grouping method
(Bonham-Carter, 1967; Text-fig. 3). The limitations of
the method employed, which include an imposition of
hierarchal structure on the data, and the lesser signif-
icance of clustering when the units compared (locali-
ties) consist of small numbers of items (genera) (Stehli
and Wells, 1971), have been recognized, and are con-
sidered balanced by the more immediate visual intel-
ligibility provided by the dendrogram. To appreciate
the distortion imposed on the similarity matrix at low
levels of association, it should be noted, by comparing
Table 1 and Text-figure 3, that while localities 2 and
5 consist of a single genus each, locality 5 appears
more similar to most others than does locality 6, which
contains ten genera.

From the dendrogram, four localities or groups of

localities were selected to be used as units for further
comparisons. The first group included localities 1, 4,
7, 8, 10 and 11: the second, third and fourth groups
were localities 3, 13 and 6, respectively. Localities 2
and 5 were not considered because of the negligible
fauna recovered. The four Palmarito groups were
compared to six stratigraphic entities in the West Tex-
as region (Table 3). While most of the similarity of
Palmarito brachiopods to Lower and Middle Leonar-
dian Texas forms comes from the first group, that
group’s closest association is with the Road Canyon
Formation fauna. The closest associations of the other
three groups are with West Texas strata younger than
Road Canyon: localities 3 and 6 with the Willis Ranch
Member of the Word Formation and locality 13 with
the Road Canyon Formation and the China Tank
Member of the Word Formation.

16 BULLETIN 313

The brachiopod fauna as a whole (Table 7) has large-
ly Late Leonardian or Early Guadalupian affinities.
This is in strange contrast to the faunal aspect pre-
sented by Arnold (1966); based on identifications by
H. M. Muir-Wood (Table 4). My own reassessment of
the brachiopod genera present in this collection (Table
4) is strikingly different, and profoundly affects the
apparent familial composition of that suite (see dis-
cussion under ‘‘Permian Ratio’’). Arnold stated (p.
2378) that Dr. Muir-Wood had indicated the age of the
unit to be Early Permian. A comparison of the genera
she reported with those from several West Texas
stratigraphic units, again using the Otsuka Coefficient,
showed the greatest faunal similarity with the Udde-
nites-bearing shale zone that lies at the base of the
Wolfcampian Series (Hoover, 1976a, pp. 61, 127).

Brachiopods, though more intensively studied in
this report, do not constitute the entire Palmarito fossil
fauna. The other fossils recovered include bryozoans,
cephalopods, chitons, corals, crinoids, echinoids, fu-
sulinids, gastropods, ostracods, pelecypods, sponges
and trilobites. These elements were forwarded to qual-
ified workers for examination. The bryozoans, chi-
tons, corals, crinoids, echinoids, ostracods and
sponges present no more diagnostic stratigraphic in-
formation than terms ranging from ‘‘Upper Paleozoic”’
to “‘Lower Permian,” but center about the latter de-
gree of refinement.

Cephalopods were recovered from several of the
Palmarito localities sampled. Drs. Furnish and Glen-
ister, of the University of Iowa, and one of their stu-
dents, Dr. Chunsun Lee, kindly identified various
coiled nautiloids from locality 1, and orthocone nau-
tiloids like Mooreoceras from several localities. Of
greater biostratigraphic importance, however, were
the identification of Perrinites hilli at locality 4, and
another locality (Field No. PRH-71-VE-12) nearby.
This form was described by Miller and Williams (1945)
from the Perija Peninsula of Colombia, and is similar
to specimens from the Chochal Limestone in Guate-
mala (collected by F. G. Stehli) and in Chiapas, Mex-
ico (collected by Millereid). A Late Leonardian age
is most likely for the deposits containing this form.
Lee (1975) has identified (at loc. 10) Martoceras sub-
interrupta, a form previously reported only from the
Upper Artinskian [Baigendzhinian] of the Urals,
roughly equivalent in age to the Cathedral Mountain
Formation of West Texas (Waterhouse and Piyasin,
1970).

Evidence from the fusulinids (Douglass, pers.
comm., 1975) tends to support these ages. Fusulinids
were recovered from two localities in the Palmarito:
one, a short but indeterminate distance down section
from locality 4, and the other from locality 6. Those

Table 3.—Comparison of brachiopod generic composition of Pal-
marito Formation fossil assemblages and (or) assemblage groups,
with West Texas stratigraphic units. Values expressed are Otsuka

Coefficient x 100; N = total number of genera included.
Palmarito Formation
Fossil Assemblages
1,4,7,8
10 & 11 3 13 6
[N=20] [N=9] [N=8] [N=10]
Word Formation 24 22 19 25
Appel Ranch Mbr.
[N = 56]
Word Formation 28 23 19 26
Limestone Lens between
Willis Ranch and Appel
Ranch Mbrs. [N = 53]
Word Formation 25 25 18 28
Willis Ranch Mbr.
[N = 63]
Word Formation 26 21 23 20
China Tank Mbr.
[N = 62]
Road Canyon Formation 38 721 23 20
[N = 88]
Cathedral Mountain 34 22 19 21

Formation [N = 83]

from the former locality were similar to Parafusulina
durhami, and to Schwagerina setum, but differ from
the latter in their larger proloculus and the presence
of cuniculi. These characters suggest a Leonardian age
for rocks at that locality. Those from locality 6 proved
to be a new species of Parafusulina, similar to P.
sellardsi, but slightly less advanced than that form,
and indicative of latest Leonardian or possibly earliest
Wordian age.

Most of the gastropods (Yochelson, pers. comm.,
1975) indicated an age of Late Pennsylvanian or Perm-
ian, but one, Cylicioscapha, from locality 11, is typical
of rocks equivalent in age to the Road Canyon or Word
Formations of West Texas.

The pelecypods appear North American in aspect,
and one, Schizodus canalis, which appears at Pal-
marito localities 1 and 8, appears elsewhere only in
Road Canyon Formation age-equivalents, supporting
a latest Leonardian age for the lower portions of the
Palmarito (Newell, pers. comm., 1975).

Trilobite fragments recovered from localities 10 and
13 were identified (Chamberlain, pers. comm., 1975)
as species of Anisopyge, which appears in the Leo-
nardian and Guadalupian of North and Central Amer-
ica.

In summary, most of the biostratigraphic indicators
recovered point to a Late Leonardian or earliest Gua-_|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 17

dalupian (Roadian to Wordian World Stage of Grant
and Cooper, 1973) age, though there are indications
(fusulinids and ammonites) that locality 10 may be
somewhat older (Baigendzhinian World Stage of Grant
and Cooper, 1973).

LITHIC AND FAUNAL ANALYSIS
INTRODUCTION

All localities from which fossils were collected for
this study were visited during July 1971 and April
1973. All lie within, or in close proximity to the type
section of the Palmarito Formation, in the Arzobispo
Chacon district of the state of Mérida, Republic of
Venezuela (Text-fig. 1).

Lithic Description Techniques

Due to the variety of rock types collected, several
methods of lithic description were employed. All rocks
were described in the field, and the usual field char-
acteristics noted. These included geographic and
stratigraphic position, where these could be deter-
mined, thickness and attitude of beds, color, gross
mineralogy and bedding characters, fossil content and
extent of exposure or outcrop. At localities 1 and 2 no
further description was possible, since the rock was
so friable that it could not be transported intact to the
laboratory. A slab approximately 0.5 cm thick was cut
from rocks taken from localities 3, 4, 5, 6 (block C),
7, 8, 10, 11 and 13. The plane of the cut was oriented
normal to bedding if the latter could be ascertained.
Both sides of the slabs were polished and X-rayed.
The X-radiographs were used as aids in the determi-
nation of depositional texture. The slabs, oiled or wet-
ted, were also examined with a binocular microscope.
Where possible (locs. 3, 4, 5, 6 (block C), 7, 10, 11
and 13) a representative chip (approximately 1 x 2
cm) of each rock type was made into a doubly-polished
thin section, using the techniques of Moreland (1968).
These sections, used in determinations of microstruc-
ture, mineralogy and depositional texture, were ex-
amined with a standard petrographic microscope. The
slides were also analyzed by X-ray diffraction, to de-
termine approximately the relative proportions of cal-
cite, dolomite and quartz present. Rocks containing
silicified brachiopod fauna were subjected to a rock
constituent analysis to test correlation of lithic and
paleoenvironmental parameters. Results were sum-
marized by Hoover (1976b). A by-product of the anal-
ysis was the discovery that the dark color of many of
the rock samples was due to hydrocarbon infiltration.
When the samples were dissolved large oil slicks
formed on the liquid and container surfaces and the

Table 4.—Genera and families of Arnold collection Palmarito
Formation brachiopods identified by H. M. Muir-Wood and P. R.
Hoover. Familial assignments follow the usage of the Treatise (Wil-
liams et al., 1965). See Hoover (1976a) for more detailed identifi-
cations.

Genera Identified

by H. M. Muir-Wood Family Assignment

Meekella vis terete Meekellidae
EISSOGHONCLESMR CE ae Chonetidae
INQGAPOWAED. soscconsseceoonas Chonetidae
Quadrochonetes .............. Chonetidae
AVONIG Whine. whe naar ae Overtoniidae
WAM ATE coscseocosneoodD us Marginiferidae
E.Ghinaurismereer renee eee Marginiferidae
Kozlowskiaienccrcreenince Marginiferidae
Productus rere ener Productidae
Bathy my OniGuaree eerie Echinoconchidae
Waagenoconcha ............. Echinoconchidae
YUTESANIG” Fete e centers eae Buxtoniidae
Aritiqualoniaaey- ria Dictyoclostidae
Reniculaurisae. cee eee Dictyoclostidae
FRU GOH oie co ais jeje itovateersiaree nets Dictyoclostidae
MNMIAAT: Sonbonssuado00o00D Dictyoclostidae
‘Cancrinella a ene ene Linoproductidae
UStediat Peper neki eee Retziidae
COMmpoOsitaies Stine es Ge Athyrididae
INeospiniferns Hosmer Spiriferidae
Phricodothyrisi suerte Elythidae

I DHALIKY ead Ooo aOR OOO So oe Dielasmatidae

Genera Identified

by P. R. Hoover Family Assignment

Meekellan C205 sheen einis sera Meekellidae

Dy Ors: -ti5,50): <a hearse Chonetidae
‘Holoticharina@e seer eerie Overtoniidae
GRIN GUIS. permies eiove nts tee Marginiferidae
iKutorcinellammerrmnn cece Marginiferidae
Echinoconchidae eee Echinoconchidae
IRAMGVECIUSH ANP eee Buxtoniidae
ReniGulauristese Peer Dictyoclostidae
I GIEGQIELTE® tee ca ose GakOOr OD Ooo Dictyoclostidae
SPUNUTONS.. rorerescnecse severest lcioe Dictyoclostidae
INPAHIOHAUE ssseadancosondodo Linoproductidae
(RAUGISDINICL Gy ae eee Linoproductidae
Hustediay (earn tn poctnns Retziidae
COTIOSTA sooccosooagaseasuae Athyrididae
INGOQYMAYOP scccoodcaccoeeoa4e Spiriferidae
Neophricadothyris ............ Elythidae

insoluble residues were much lighter in color. Solid
residues (carbonized plant fragments, pyrite) indica-
tive of a euxinic depositional environment were not
recovered.

The descriptive terminology used follows two
schemes: compositionally, the carbonates are char-
acterized by the Folk (1962) classification; in terms of
depositional texture the Dunham (1962) classification
is employed.

18 BULLETIN 313

Faunal Lists

Although a resume of the brachiopod fauna of each
locality appears as a part of Text-figure 4, a separate
presentation within the discussion of each locality
gives a better concept of the entire bed assemblage.
The number following each brachiopod species indi-
cates the minimum number of individuals that could
have provided the number of valves and shells ob-
served. The initials in parentheses accompanying oth-
er taxa refer to the individuals who were kind enough
to provide identifications within their own areas of ex-
pertise (see ““Acknowledgments’’). Where no other
information is given, the identification is mine.

Taphonomy

In recent years there has been increasing interest in
the taphonomic history of fossil organisms and their
remains (e.g., Lawrence, 1968; Boyd and Newell,
1972; Erdtmann and Prezbindowski, 1974). Post-death
processes contribute in great measure to the final as-
pect of the fossil assemblage as seen by the investi-
gator. Although Boyd and Newell define taphonomy
as ‘‘mode of entombment,”’ I consider it to include all
post-death alterations in the remains of a once-living
organism, including not only its interactions with liv-
ing organisms and with the chemical and physical en-
vironment, but also changes wrought by the investi-
gator during sampling and preparation.

The mode and extent of breakage of fossils, by
whatever means or cause, is often held to be signifi-
cant in inferring the environment of deposition of fos-
sils (e.g., Waterhouse and Piyasin, 1970). Observa-
tions of recent shelf benthos would indicate that
bioturbation might be a significant disruptive influ-
ence, but Thayer (1979) suggests that the high diver-
sity of sessile benthos adapted to life on soft substrates
may be related to a smaller number of bioturbating
organisms, and hence a lower incidence of bioturba-
tion below the Permo-Triassic boundary. The environ-
ment of deposition is, however, only one place where
that destruction may occur. The bumps, jars and abra-
sions of aqueous transport and the packing of fossils
during deposition must account for some of the ob-
served shell injuries. Compaction of the unconsolidat-
ed or partially consolidated sediment column places
stresses on the enclosed shells that may result in
crushing or breakage. Later tectonic movements, ac-
companied by slippage, flow or breakage, can, in fos-
siliferous rocks, easily break the enclosed fossils.
Such broken fossils may later be recemented in their
crushed forms by precipitates from fluids passing
through the rocks. Fossils are often broken during col-

lection; a common expression of this is the decorti-
cation of calcareous fossils that are cracked out of a
calcareous matrix. During etching, crushing of silic-
ified specimens by each other, the surrounding rock
or insoluble residues, or by the buildup of carbon diox-
ide gas within the shells, is not uncommon. For all of
the above reasons it is important that the paleontolo-
gist who would be a paleoecologist be interested in,
and report to colleagues on the methods under his
(her) control that were used in the various stages of
collection and preparation, in order to assess the dam-
aging effects those operations may have had on the
fossils described.

Boyd and Newell (1972) discussed a Permian assem-
blage consisting largely of silicified pelecypods, as-
sumed to have been originally composed of the same
aragonitic or high-magnesium calcite shared by most
of their modern relatives. These chemically unstable
remains were altered in ways that are rarely duplicated
among roughly contemporary brachiopods, because
the latter are thought to have been composed in life
of more stable low-magnesium calcite. Chave (1964)
and Lawrence (1968) have dealt at length with the
chemical causes and preservational implications of
differences in carbonate shell mineralogy. The artic-
ulate brachiopods, among carbonate-shelled Permian
marine invertebrates, are the most likely candidates
for preservation, in terms of chemical stability of orig-
inal shell material.

As my study deals largely with silicified fossil as-
semblages, at least a cursory discussion of silicifica-
tion seems in order. The mechanism of silicification is
unclear, although it has been suggested (Emery and
Rittenberg, 1952; Siever, 1962) that changes in the par-
tial pressure of CO, and in pH that accompany the
decomposition of organic soft tissues in sea water or
interstitial fluids could provide a proper chemical re-
gime for replacement of calcite by silica or vice versa.
Palmarito fossils provide evidence that at least two
distinct silicification mechanisms operated there. Ap-
parently the percentage of magnesium replacing cal-
cium in the mineral calcite, and the crystal structure
of the two forms of calcium carbonate (calcite and
aragonite) play a part in determining the susceptibility
of original carbonate shell to either or both dissolution
and replacement by silica during diagenesis (Chave,
1964). As a result of diagenetic changes, the extent of
magnesium substitution in the calcite lattice may
change within a single shell, so that a variable suscep-
tibility to silicification exists. When this is so, silicifi-
cation may be incomplete or selective, and fossils like
those of Echinauris cf. E. lappacea Cooper and Grant
(1975) (loc. 8), may be formed. In these (see PI. 5, figs.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 19

18, 19) the exterior of the ventral valve and a mold of
the inside of the dorsal valve are silicified. The hollow
interior of the fossil is lined by drusy silica, and retains
no vestige of original organic structure. Boyd and
Newell (1972) suggested an alternative origin of such
fossils. They invoke geode-type infilling of voids in
semi-consolidated or consolidated sediments by silica-
bearing solutions. Another mode of silicification in-
volves the filling of such a leached-out void by cal-
careous micrite, which is subsequently silicified. This
process forms natural casts composed of numerous
discrete grains, rather than continuous opaline silica.
The micrite apparently enters these voids via partings
along bedding, breaks in the consolidated sediments,
or via erosionally re-exhumed extremities of the voids
themselves. Both types of silicification have been ob-
served in Palmarito Formation fossils. Only the first
occurs commonly among the articulate brachiopods,
the other being largely limited to the molluscs.
Several kinds of data were collected to assess the
importance of the energy regime of the depositional
environment, and other taphonomic factors in produc-
ing the breakage observed in any assemblage. Relative
numbers of dorsal and ventral valves, and articulated
shells of each species recovered were noted (see Text-
fig. 4). The minimum number of individuals to which
the observed valves might be attributed was noted as
an aid in determining the significance of each count.
Waterhouse and Piyasin (1970) and Sheehan (1978)
have noted that such numbers and the valve ratios
derived therefrom can be quite misleading unless fur-
ther qualified. The architecture of Permian brachio-
pods was so variable that shells of different genera
were differentially resistant both to breakage and dis-
articulation after death. Most productids probably dis-
articulated quite readily after death, there being little
skeletal hinge structure to keep the valves together.
In addition, the dorsal valve in this group tends to be
less massive and more fragile than its ventral coun-
terpart, and is more commonly broken or missing. The
globose spiriferidines (e.g., Hustedia, Composita,
Neophricadothyris) are commonly found articulated,
since their complex articulatory hinge structure was
sufficient to keep the valves together under consider-
ably greater current or wave activity. Most other types
of brachiopods fall between these two extremes. Sub-
jective estimates of wear on shell were made, both
from whole specimens and polished thin sections.

Paleoecology

Taphonomy and paleoecology are really two parts
of the same inferential process: the study of taphon-
omy permits the selective removal of some of the bias

that hinders complete understanding of the paleoecol-
ogy of a fossil assemblage. Many authors have rec-
ognized and defined fossil communities, and in doing
so have relied heavily on the relative abundances of
the various species present. They have stressed that
there must be convincing evidence of in situ deposi-
tion, before inferences concerning community type
can be drawn, but Lawrence (1968) among others, has
stressed that transportation is probably not nearly so
important a factor as simple preservation. He esti-
mated that 40 to 70 percent of a living community may
be elminated from the fossil record by non-preserva-
tion alone. Thayer (1979) however, suggests there may
be less postmortem non-preservation in Paleozoic than
in modern benthic deposition. The extremely complex
taphonomic histories of the various Palmarito fossil
assemblages have probably altered, in no recognizably
systematic way, the percentage composition of the
original living community. For this reason no attempts
were made here to analyze the significance of relative
abundances of fossils unless these numerical abun-
dance differences were striking.

Exposure of the Palmarito in isolated exotic blocks
makes comparisons of large-scale lateral or vertical
changes in species or assemblages impossible. Even
within the type and reference sections of the forma-
tion, one cannot be certain of the original relative
stratigraphic position of samples, because severe
structural deformation has taken place. Paleoauteco-
logical reconstructions here are limited to compari-
sons, however distant, with living representatives of
the phylum, inferences from preserved morphology
and associated organisms and sediments. Most of
these subjects are covered in the individual systematic
discussions. Within the Palmarito samples some pa-
leosynecological inferences can be drawn. These are
discussed under “‘Permian Ratio”? and ‘‘Sampling Ef-
ficiency Index.”’

COLLECTING LOCALITIES

Locality 1 consists of one wall of the stream bed
near the head of a small stream locally known as the
Quebrada de Portachuelo (Quebrada Queveda of Ar-
nold, 1966), roughly 100 m downstream (up section)
from the highest redbed layer of the Sabaneta For-
mation, which is the base of the Palmarito Formation
(see Text-fig. 1). The rock exposed is a petroliferous,
dark gray, fossiliferous, fissile siltstone, containing
occasional small lenses of silty limestone. A block of
about one cubic m, which had slipped down from the
wall and lay close to its base in the stream bed, formed
the actual site of collection. Fossils were removed by
hand from the weathered rock over an area of about

20 BULLETIN 313

one square m, through a stratigraphic thickness of
about one-half m. They were preserved entirely by
calcite permineralization, and all were dark gray to
black in color. Although the friability of the rock pre-
vented the return of bulk samples to the laboratory,
field examinations allowed determination that the rock
was compositionally a biomicrite. Draping of sedi-
mentary laminae around more resistant skeletal grains
(crinoid stems, ramose bryozoa) indicated that soft-
sediment deformation had taken place, and that in
terms of depositional texture the rock was a pack-
stone. The crushed shells of many of the more fragile
fossils confirmed this. Fossil collections returned to
the laboratory were cleaned using an S. S. White Air-
brasive, and delicate structures were developed using
common mechanical techniques. Among the fossils
recovered from the locality were:

BRACHIOPODS
Anemonaria? cf. A. sublaevis (King).....-....++++++++++++- 1
Composita cf. C. pilula Cooper and Grant ................. l
Echinauris cf. E. liumbona Cooper and Grant .............. 5
I GUD ARS beectoone GOD DRE onmecning wen castonHmmasaMnecan 1
Kutorginella cf. K. umbonata (Muir-Wood and Cooper)..... . 1
Neophricadothyris cf. N. crassibecca Cooper and Grant..... 7
Neospirifer venezuelensis (Gerth) ...........-...22.0..005-- 4
Peniculauris subcostata latinamericana n. ssp. ........---+-- 29
Rugatiaioccidentalisa (NEWDEnLY) martin eit eater ritter 33
Stauromataresorericam- Pens anGiSperayvess t-iieliel ese) al eta tele 9
BRYOZOA

Timanotrypa? sp. (OLK)
indeterminate ramose, encrusting and fenestellid forms

CEPHALOPODS
(WMF; BFG)
coiled nautiloids aff. Titanoceras-Metacoceras-Fordiceras
CORALS
(CTS)
Lophophyllidium aages (Jeffords)
indeterminate lophophyllidiids?
ECHINODERMS
Haertocrinus? sp. (calyx plate) (JJB)
columnals
GASTROPODS
(ELY)
Straparollus (Euomphalus) sp. indet.
?Taosia sp. indet.
PELECYPODS
(NDN)

Megadesmus cf. gryphoides
Schizodus canalis Branson

Most brachiopods and other fossils were severely
crushed, but the fragments were rarely dispersed. This
crushing was most commonly dorsoventral in the bra-

chiopods, but occurred in many other orientations.
The rarity of fragment dispersion suggests that the de-
structive mechanism was loading and compression of
soft sediment prior to lithification, rather than current
or wave action. The dark color of the rock at this and
most other Palmarito localities is probably entirely the
result of hydrocarbon infiltration (see discussion under
‘“‘Lithic Description Techniques’’), and no inferences
of euxinic conditions in the depositional environment
are made. The high percentage of muds which make
up the rock might ordinarily be taken as evidence of
a low energy regime in the depositional environment,
but the asymmetry of the valve distributions of the
brachiopods (Text-fig. 4) suggests that moderate wave
or current energy conditions were present. The abun-
dant bryozoans may have served as baffles to currents
near the bottom, trapping finer sediments and provid-
ing protected places where organisms adapted to qui-
eter habitats could thrive. Many of the brachiopods
show traces of a diverse epifauna, of which only a
very few body fossils have been preserved. Biotur-
bation by vagile organisms (gastropods, pelecypods),
in addition to current activity and post-depositional
loading, may have contributed to shell breakage (but
see Thayer, 1979, for arguments opposing this). None
of the fossils shows much abrasion, suggesting that
asymmetry of the valve distributions is a function of
current activity within the local environment rather
than transport from outside. The total assemblage
does not appear to have been severely crowded, as no
shell asymmetry indicative of growth under crowded
conditions was observed that could not be attributed
to taphonomic processes or a natural proclivity of the
organism for such a mode of growth (e.g., Hustedia).
The depositional environment is interpreted as having
been close to the life environment of the organisms
preserved, and to have been located in shallow, warm
water of moderate current activity, probably below
wave base.

Locality 2 lies in the Quebrada de Portachuelo,
about 100 m downstream (up section) from locality 1
(Text-fig. 1). The rock from which the fossils were
collected is a petroliferous dark gray shale, with thin
(ca. 5 cm thick) intercalated lenses of calcareous silt-
stone. Although the rock was so friable that no sam-
ples could be transported intact to the laboratory for
sectioning or slabbing, the rock could easily be called
a biomicrite in compositional terms. There is evidence
of soft-sediment deformation, in the dorsoventral
crushing of many fossils, and the resultant deposition-
al texture could be termed a wackestone or incipient
packstone, depending on the local fossil density. The
actual collecting site lay directly within the side wall

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 21

of the stream bed: the size of the area collected was
about one m parallel to and one-half m normal to bed-
ding. All fossils collected were preserved by calcite
permineralization, and in addition were heavily infil-
trated by hydrocarbons, giving them a uniformly dark
color. The shale proved unusually adherent, and con-
sequently considerable amounts of material were
cleaned by etching in 52% hydrofluoric acid, using an
adaptation of a technique developed for ostracods by
Sohn (1956). This dissolved the siliceous shales and
converted the calcite shells to fluorite. The resulting
pseudomorphs were semi-transparent (Pl. 2, figs. 17—
22) and allowed inspection of some internal details,
but the conversion to fluorite unfortunately also in-
volved an increase in (crystal) unit cell size, so that
specimens over about 1 cm in length were invariably
broken, while smaller specimens were commonly de-
corticated. Among the fossils recovered were:

BRACHIOPODS
DYOROS: CAMA VALE WG Gos. Sugaasoausewe Soon OOO ODDO SeCoOn 120
indeterminate productidine fragments ...................... 3
ECHINODERMS
columnals
OsTRACODS
(IGS)

Acratia? sp.

Bairdia (sensu lato) spp.
Cavellina sp.

Ceratobairdia? sp.

Healdia sp.

Hollinella spp.

indeterminate ostracods (3 types)

Most of the brachiopod fragments have been dor-
soventrally crushed, probably as a result of soft-sed-
iment compaction by loading. The valve distribution
(Text-fig. 4) is symmetrical, indicating that although
some shells were disarticulated, few if any were de-
stroyed. Most of the disarticulation probably resulted
from hydrofluoric acid etching and concomitant size
increase. Examination of specimens in the rock before
etching revealed few if any disarticulated specimens,
other than those produced by splitting of the shale.
There is no evidence of the sort of wear that would be
incurred in transport from outside the environment of
deposition. That environment is interpreted as having
been in shallow water of low current energy, with a
soft substrate. The absence of pediculate or cemented
brachiopods may indicate that the initial grain size of
the carbonate sediment was very small, so that no real
support for a holdfast organ like a pedicle existed. This
inference may in turn be supported by the overwhelm-
ing dominance of a single form whose flattened valves
made it peculiarly adapted to life on a soft substrate.

Locality 3 lies within the Quebrada de Portachuelo,
at the brink of the first high (over 5 m drop) waterfall
encountered when proceeding downstream from the
head of the stream (Text-fig. 1). Samples were col-
lected over a lateral distance of one m through a strati-
graphic interval of about one m. The rock, assignable
to the Upper Palmarito limestones as conceived by
Arnold (1966), occurs in thick to massive beds, sepa-
rated by partings of medium gray calcareous siltstone.
The limestones are dense, petroliferous, dark gray
silty limestones, compositionally biomicrites. The
rocks do not appear to have been compacted by soft-
sediment deformation as have some others in the Pal-
marito, and in terms of depositional texture are wacke-
stones. In addition to calcareoous and silicified skel-
etal grains, clasts include sand- and silt-sized anglular
quartz and rock fragments, and numerous small sili-
ceous spheres. These latter may be of volcanic origin.
Much of the rock is laminated, and included within
the laminae are numerous euhedral dolomite rhombs.
Cracks of probable tectonic origin cutting both rock
and fossils have been filled by calcite. All fossils col-
lected from this locality were silicified and were pre-
pared for study by hydrochloric acid etching. The
quality of the silicification is very good, and no geode-
fillings or micrite envelopes of the type described by
Boyd and Newell (1972) were observed. Among the
fossils recovered were:

BRACHIOPODS

Cleiothyridina cf. C. nana Cooper and Grant ............... 2
Composita cf. C. pilula Cooper and Grant ................. 3
Derbyiaispe re ee aii re Re ee eee 2
LEAN I KIQOTATAND We. Ss socounsnccavosovenooneboonacec 20
MeekellaiskenoidesiGitt\vmerrer ore eee nee eee eee 33
Oligothyringesp se sce coerce ee ie COC eee 34
Pontisia cf. P. stehlii tumidosa Cooper and Grant........... 33
SPIN rOns.)) Cla. SeisrandicOsta MeSPaekice amie 1
Spiriferellinarct. Swnilli(Girty) eerste eee ee aeeee 29
BRYOZOA
(OLK)

indeterminate fistuliporids

CORALS
(CTS)

indeterminate solitary rugose forms

ECHINODERMS

columnals

GASTROPODS
(ELY)

Anomphalus n. sp.

Apachella aff. A. franciscana (Chronic)
Apachella sp. indet.

?Cibecuia sp. indet.

22 BULLETIN 313

Dichostasia complex Yochelson
Discotomaria cf. D. basisulcata Batten
Discotropis sp.

?Lamellospira sp.

Orthonema sp. indet.

Straparollus (Euomphalus) sp. indet.
““Strobeus”’ sp. indet.

Worthenia sp. indet.

new genus of high-spired gastropods
?pleurotomariaceans (2 genera)

SPONGES
(JKR)

Colospongia sp.

Cystothalamia sp. (nov.?)

Defordia cf. densa Finks
Girtyocoelia cf. dunbari King, 1943
Girtyocoelia n. sp.

The valve distributions of brachiopods with equiv-
alently durable dorsal and ventral valves are notice-
ably symmetrical (Text-fig. 4). There was probably lit-
tle transport: the fossils lived near where they were
buried. Although the fossils were extensively frag-
mented, most of this can be attributed to post-burial
taphonomic processes. Cracks that pervade the rock
were formed after lithification and are probably of tec-
tonic origin. During etching, the secondary, crack-fill-
ing calcite between separated portions of many shells
was dissolved and the valves when recovered, were
broken.

The sea floor here is interpreted as a combination
of hard and soft substrates. Initially it had a soft mud
bottom. Some of the brachiopods recovered (Com-
posita, Cleothyridina, Hustedia, Spinifrons?) are
clearly adapted to life on such a substrate. The settle-
ment of such potentially large siliceous sponges as
Defordia, probably initially on the living or dead shells
of the above brachiopods, provided larger areas of
hard substrate to which other forms might attach. In-
deed, numerous specimens of Meekella and Spirifer-
ellina (both pediculate forms: see Schiimann, 1969)
have been recovered partially overgrown by sponge
tissue near the beak, suggesting that these forms lived
attached to the sponges. The dark color of the lime-
stone is probably entirely the result of hydrocarbon
infiltration, and not of euxinic conditions in the de-
positional environment, but the presence of dolomite
rhombs in some sedimentary laminae may indicate
that the water there had been somewhat hypersaline,
and that access to open ocean water was limited. If
negative evidence can be admitted, no open water
forms such as ammonoid cephalopods were found in
the residues, and none was observed in polished slabs
or sections. In addition, none of the vagrant pelecy-
pods found at other Palmarito localities were re-

covered. The environment of deposition is interpreted
as having been one of moderate to low current energy,
in warm, shallow water, possibly with restricted ac-
cess to the open ocean.

Locality 4 lies within the Quebrada de Portachuelo
about 100 m upstream (down section) from locality 3
(Text-fig. 1). The area sampled comprises about 2 m
laterally and one m normal to bedding. The rocks are
exposed in the side wall of the stream bed, and lie
almost vertical. They consist of thin- to medium-bed-
ded silty limestones, intercalated with thin-bedded cal-
careous siltstones. Compositionally a biomicrite, in
terms of depositional texture the rock would be clas-
sified as a packstone. In addition to the large numbers
of calcareous and silicified skeletal grains present, the
rock contains many sand- and silt-sized siliceous
spheres, which may be of volcanic origin. Also present
are abundant fine, needle-like calcitic forms that are
interpreted as calcareous and (or) calcified (originally
siliceous) sponge spicules. Large bodies (up to 10 cm
in largest diameter) of consolidated sediment with thin
silicified rinds occur commonly within otherwise lam-
inar limestones. The finer sediments outside are
draped and compressed around them, but this may be
due to the weight of these large bodies rather than to
loading by overlying sediments. Recovered fossils are
partially or totally silicified, the former being the more
common. Although many calcareous fossils were also
present, none was recovered, as the fossils were pre-
pared for study by etching in dilute hydrochloric acid.
No silicified micrite envelope casts were found. Since
the limestones here were among the muddiest encoun-
tered, etching was quite slow, and the few mm of de-
calcified silt produced during a week’s etching. were
removed from the dried block using an S. S. White
Airbrasive unit. Among the fossils recovered were: -

BRACHIOPODS
Chonetinetes cf. C. varians Cooper and Grant .............. 3
Composita cf. C. pilula Cooper and Grant ................. 11
Derbyiarauriplexagne Spiye-trtets steler-i-talser ete teeta 2
Derbyia cf. D. complicata Cooper and Grant ............... 1
Der byia isp re yctsistercteleis casrersieiste isis ieee eet eh one 1
Echinauris cf. E. liumbona Cooper and Grant .............. 13
Holotricharina hirsuta Cooper and Grant.................-. 8
Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ....- 14
MeekellaiskenoidesiGitty, eictes scatter ota teen eee 6
Neospirifer venezuelensis (Gerth) ..........2..0s0eeeeeeeeee 1
Rugalia intermedia ny Species ciseisieeeieeiekeieieleite eee 2m
SPIO AI Sie Sa ARAGON NS Bob oncasoooccageeconusece- 1
Stauromata esoterica n. gen. and sp. ..........+--eeeeeeeee 1
BRYOZOA

indeterminate ramose and fenestellid forms

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 23

CEPHALOPODS
(WMF; BFG; CSL)

Perrinites hilli

ECHINODERMS

columnals

GASTROPODS
(ELY)

Goniasma sp. indet.

Palaeostylus sp. indet.

“Worthenia’’ cf. W. corrugata H. Chronic
new genus aff. Taosia

PELECYPODS
(NDN)

Parallelodon sp.

The only brachiopods from which substantial num-
bers of complete shells were recovered were those
which could have lived comfortably on a soft muddy
substrate. The valve distribution of Meekella (Text-
fig. 4) is unusual. At locality 4, mostly dorsal valves
were recovered, in contrast to locality 3, in which sub-
equal numbers of both valves were found. It is inferred
that the population of Meekella sampled at locality 4
grew and lived elsewhere, and that the disarticulated
dorsal valves were transported a short distance to this
soft-substrate burial environment. The fragmentation
or relatively poor preservation of many of the fossils
cannot be entirely attributed to either partial silicifi-
cation or faulty preparation, but rather to transporta-
tion of dead shells from elsewhere. This suggests that
the deposit is largely allochthonous. Judging from the
fine sorting and coarsely graded bedding seen in thin
section and polished slab, the environment of depo-
sition was one of moderately strong current and (or)
wave action, although the alternation between thin,
fossil-barren siltstones and thin, sparsely fossiliferous
silty limestones, and the lack of abrasive wear on most
fossils indicate that the duration of high energy con-
ditions was not long. Soft sediment deformation ap-
pears to have been minimal here, that observed being
mostly around the numerous bodies of consolidated
sediment, here interpreted as rip-up clasts, which
could have produced load structures, such as draped,
compressed sedimentary laminae, by virtue of their
own weight. These are interpreted as having been de-
posited in shallow, warm water, above a soft sub-
Strate, but near to the area from which the fossil debris
recovered was derived. The rip-up clasts and the pres-
ence of disarticulated valves of such relatively strong-
ly articulated brachiopods as Meekella indicates that
a moderately strong current regime of short duration
(‘storm’’) would be a likely agent of transportation
and production of rip-up clasts. Similar deposits in the

Ordovician of Quebec (Bretsky and Bretsky, 1975),
the Devonian of New York (Bowen, Rhoads, and
McAlester, 1974) and the Jurassic of Morocco (Ager,
1974) have been interpreted as having been caused by
storms.

Locality 5 consists of a large (ca. eight cubic m)
exotic boulder that lies along the mule trail between
E] Portachuelo and Palo Quemado, about one-quarter
the distance from the former to the latter (Text-fig. 1).
Several sample blocks were removed from the surface
of this boulder. The block lies within exposures of the
Sabaneta Formation, and was clearly derived from in-
accessible Palmarito Formation outcrops upslope. The
rock is a medium-gray, massive, petroliferous lime-
stone which in the field appeared to contain numerous
large silicified productids. Accordingly, large amounts
of the rock were collected. Unfortunately the silicifi-
cation was poor and only a single identifiable specimen
of a brachiopod was recovered. In polished slab the
rock is essentially featureless, with only the occasional
randomly oriented, partially silicified shell standing
out. In thin section however, one can see that most of
the dark coloring present is caused by infiltrated hy-
drocarbons, and that most of the grains present are
not silicified. With the exception of the few stringers
of coarse silt- and clay-sized material, the sedimentary
grains are of sand-size or larger. Most are skeletal in
origin, but rare dolomite rhombs are present in the
sand-sized fraction of the sediment. Compositionally
the rock would be a calcarenite; in terms of deposi-
tional texture a packstone. Many intergranular bound-
aries are fused, and numerous stylolites have appar-
ently served as pathways for hydrocarbon migration.
Among the fossils recovered in etching or observed in
polished slab or thin section were:

BRACHIOPODS
Peniculauris subcostata latinamericana n. ssp. ............. 1

CEPHALOPODS

indeterminate large orthocone and coiled nautiloids

FORAMINIFERA

(RCD)
Geinitzina sp.
Globivalvulina sp.
Pachyphloia sp.
indeterminate textulariid
GASTROPODS
(ELY)

Apachella sp.

Bellerophon (?Pharkidonotus) sp. of Yochelson, 1960
Naticopsis cf. N. obla us Winters

Orthonema sp. indet

Palaeozygopleura sp. indet.

24 BULLETIN 313

Straparollus (Euomphalus) sp. indet.
Taosia sp. indet.
“Yunnania”’ sp. indet.

The rock appears to have been somewhat compact-
ed, probably by the same force that compacted the
assemblages at localities 1, 2, 7, and 11, but here the
sediments (calcareous sands) were mechanically com-
petent and reacted to the stress by the welding of some
grain boundaries and the formation of stylolites. The
rarity of fine particle sizes and the moderately good
sorting of the calcareous grains in the sand- and gravel-
size fractions indicate that this rock may have origi-
nated as a bar deposit. Certainly high energy condi-
tions are indicated, to abrade and sort the fragments
to this degree. The larger silicified fossils present (bra-
chiopods, cephalopods, gastropods) are interpreted as
having been derived from some outlying environment,
in much the same way that pelecypods are washed
onto well-sorted modern beaches. The absence of
much terrigenous material in the rock suggests that
either the adjoining land was of low relief, or that this
was a bar rather than a beach deposit. The environ-
ment of deposition probably lay within wave base, in
very shallow water, and indeed may have been in part
emergent. The dolomite present may indicate limited
access to open ocean environments. The absence of
sedimentary structures characteristic of beach or bar
sands may be due to extensive bioturbation by the
gastropods (or other organisms that have not been pre-
served as fossils).

Locality 6 consists of a rolled exotic block located
beside the mule trail that connects El Portachuelo and
Mucuchachi. This trail closely follows the eastern
flank of the Quebrada de Portachuelo (Text-fig. 1). The
entire block comprises about two cubic m. When first
discovered (1971) the block was almost entirely cov-
ered by vegetation, and only a small sample was re-
moved from its top. Laboratory recognition of its pe-
culiar fossil fauna prompted re-collection of large
samples from the bottom (block A), middle (block B),
and top (block C) when I revisited the locality in 1973.
All three levels appeared in the field to be framework-
supported, thick-bedded, petroliferous, light gray to
tan silty limestones, bearing numerous finely silicified
fossils. These limestones were separated by incon-
spicuous, thin (ca. 1 cm thick) siltstone partings. The
fossils were recovered from all blocks by hydrochloric
acid etching. Beyond valve separation of shells of the
easily disarticulated productaceans, little taphonomic
alteration has disrupted the fossil assemblage. None
of the fossils shows signs of abrasive wear, and most
asymmetric valve distributions are explainable by
either differential structural stability of the two valves

involved, or by susceptibility of the valves to current
transport. Thin-section and polished slab analysis
shows all three blocks to be compositionally spicular
biomicrites, and, in terms of depositional texture,
wackestones or boundstones. Among the fossils re-
covered from the three blocks were:

BLock A
BRACHIOPODS

Anaptychius minutus ngen.andSp. eee en eee eee 24
Aneuthelasma)globosum 0: (Sp) ...2=- -)-12e ace ee eee eee 15
GCollemataria venezuelensis| 0) Sp.) errr ee eee 45
Cooperina inexpectata Termier, Termier and Pajaud......... 57
Gosticruratminutan. (gen. and isp. sa -).te ee eee 20
lHustediavhyporhachisim= spy -aatedeee en eee ee eee 13
Petrocrania teretis Cooper and Grant ..................205- 11
XENOStEZES MINUS CUIUS De SD) 1.1022 eee eee eee 36

BRYOZOA

indeterminate ramose and fenestellid forms

GASTROPODS
(ELY)

Holopeiform gastropod indet.

New genus aff. Orthonema

New genus of high-spired gastropods
Pleurotomariacean gastropod indet.

PELECYPODS
(NDN)

Pegmavalvula gloveri Newell and Boyd

SPONGES
(JKR)
Defordia cf. densa Finks
Guadalupia(?) sp.
BLock B
BRACHIOPODS

Anaptychius minutus n. gen. and sp.............-2+-22+e0e> 6
Aneuthelasma globosum 1s Sp. os. see eee ee eee eee 24
Cooperina inexpectata Termier, Termier, and Pajaud ........ 13
Costicruraiminuta ms gens andispy =... 2-. 42-2 e eee 6
Hustediathyporhachisimsps ... 42-5 «+ 2221 2- eeeeeee 4
Rhynchonellacea, family uncertain......................05- 2
XCHOSLESESWIMINUSCULUS Mn SPieaiedsncicl-isiee keene 5

BRYOZOANS

indeterminate ramose and fenestellid forms

CORALS
indeterminate solitary rugose forms
FUSULINACEANS
(RCD)
Parafusulina cf. P. sellardsi
GASTROPODS
(ELY)

Orthonema sp.
Platyworthenia sp.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER DS

New genus aff. Taosia
New genus of high-spired gastropods

PELECYPODS
(NDN)

Pegmavalvula cf. gloveri Newell and Boyd

SPONGES
(JKR)

Defordia cf densa Finks
Guadalupia cf. williamsi King

VERMES
(ELY)

two or more forms of Spirorbis or similar attached worm tubes

BLock C

BRACHIOPODS

FAA DIY CHIUS MINUTUS Me/SeNs ANd SPs .c.c wo oe occre sarees 21
mAneuthelasma globOSuMm MN. SPs w:- yee) < 101s. 0 esters oie) 2 212 s/eyels he 38
Cooperina inexpectata Termier, Termier, and Pajaud ........ 99
MOsncr uy ayninulaan fen: and Speen ince ce cciecicieis ees ee 30
BIEL DNIGES D earete roe ays tosey sists fey ois, sie one ekovanis eps: oyoseis @88 vee en eles 1
Hchinauris bella Cooper and Grant ..................-:-..- 1
BTESECALCYILY D OFLA CHISUTICIS) sueestets eieeevedai oi. oiaceelevs es. Facies ole) oe 20
fmetrocrania teretis Cooper and Grant .....5.....22..500:--.- 2
Rhynchonellacea, family uncertain......................... 4
MCHOSTE SESIIMINUSCHUIUSIM: ISP s/s a)o eins a) eyaicl sis eie,ie sees oe cide 130
BRYOZOA

indeterminate ramose and fenestellid forms

CoRALS

indeterminate solitary rugose corals
small fragment of tabulate coral ?Acaciapora sp. (CTS)

GASTROPODS
(ELY)

2Orthonema sp. indet.

Holopeiform gastropod indet.

New genus of high-spired gastropods
Pleurotomariacean gastropod indet.

OsTRACODS
(IGS)
Cavellina? sp.
Hollinella sp.
Roundyella sp.
indeterminate bairdiids
PELECYPODS
(NDN)
Acanthopecten sp.
Girtypecten sp.
SPONGES
(JKR)
Defordia cf. densa Finks
VERMES
(ELY)

two or more forms of Spirorbis or similar attached worm tubes

Although the faunules recovered from the three
blocks at locality 6 are similar, they are not identical.
Numbers of brachiopod individuals probably better
reflect intensity of picking of the acid-insoluble resi-
dues than real diversity: relative numbers of individ-
uals within the faunules may be more significant. All
three blocks contain faunas that are largely adapted to
life on a hard substrate. The tiny Costicrura is similar
to Cruricella Grant (1976) from Thailand. Grant (1976,
pp. 189-190) suggests that that small pediculate form
lived closely appressed to a hard substrate, so closely
indeed that in order to open its valves it would have
had to relax its pedicle. When solidly fixed, beaks of
both valves would have been in contact with the sub-
strate, making shell gape impossible. Costicrura may
well have shared this habit. Certainly it is found only
in association with extensive hard substrates such as
those provided by the sponge Defordia. Few free-liv-
ing brachiopods are present in the assemblages. Only
those generally conceded to be among the hardiest of
Tethyan forms (e.g., Hustedia) lived on the soft sub-
strate in this assemblage, and most others adapted to
that substrate were probably derived from outside.
Most of the brachiopods lived above the sea floor,
attached to sponges. The three blocks sampled at lo-
cality 6 probably represent three microenvironments
within a larger incipiently biohermal environment.
Block A is best characterized by the presence of the
lyttoniid Collemataria, which appears nowhere else
in the Palmarito Formation. Block B contains numer-
ous specimens of Parafusulina, which is absent from
both blocks A and C. Block C is characterized by the
pelecypods Acanthopecten and Girtypecten, rather
than Pegmavalvula, which appears in the other two
blocks. The basic substrate is apparently the same in
all three places: a soft substrate of biomicrite upon
which sponges and clams have provided a secondarily
hard surface. It would be tempting to suggest that a
factor like salinity, energy, or depth differences was
responsible for these apparently discontinuous distri-
butions, but it is more likely to have been a complex
combination of such factors. It is likely that the three
microenvironments were contemporaneous and later-
ally discontinuous, patterns that are reflected in ver-
tical section. The fine calcareous biomicrite that forms
the basic soft substrate here probably settled out when
moderately strong currents struck such effective baf-
fles as the fenestellid bryozoans and anastomosing
sponges. These currents were probably the agent that
produced the asymmetrical valve distributions (Text-
fig. 4) in all but the most tightly articulated forms (e.g.,
Anaptychius). The environment of deposition is inter-
preted to have been in shallow, warm water, of mod-

26 BULLETIN 313

erate current activity. The lack of noticeable amounts
of terrigenous material suggests that it was not near
a shoreline of high relief. It appears to have been in
a less restricted area than that represented by locality
3, as it lacks the dolomite rhombs so prevalent there.

Locality 7 was a paving stone in the mule trail be-
tween Palo Quemado and Mucuchachi, about 1 km
northwest of Palo Quemado, and about 200 m toward
Palo Quemado from the small chapel locally known as
Capilla de la Santa Cruz de Palmarito (Text-fig. 1).
This is on the old trail connecting Mucuchachi and
Santa Barbara de Barinas, and the locality lies within
the type section of the Palmarito Formation as defined
by Christ (1927). Although out of place there, the rock
sampled is definitely from within the formation. The
outcrop from which it was derived, however, could
not be located. The block was about one m square and
one-fourth m thick, and consisted of a dark gray, pet-
roliferous, fossiliferous, fissile, very silty limestone.
Field examination using dilute HCl discovered no
silicified fossils, but crackouts were so promising that
a large amount of material (almost the entire block)
was collected. Preparation was entirely by mechanical
methods. In thin-section and polished slab examina-
tions, the rock proved to be heavily infiltrated by hy-
drocarbons that probably accounted for most of its
dark color. Within the sand and silt fractions there was
primitive sorting, and some thin graded beds (on the
scale of the thin-section), but in general the rock was
poorly sorted. Compositionally a biomicrite, it con-
tained large numbers of apparent sponge spicules and
abundant angular skeletal and quartz grains and rock
fragments scattered through the micritic groundmass.
The rock showed signs of having suffered soft-sedi-
ment deformation: laminar fine sediments draping over
clasts, crushing normal to bedding, and considerable
apparent recrystallization and welding at intergranular
boundaries had taken place. In terms of depositional
texture the rock is a packstone. Few brachiopods
showed an asymmetrical valve distribution (Text-fig.
4). Among the fossils recovered from this locality
were:

BRACHIOPODS

PACOSATIMANES Dae inie cern ere er acini taietetcrecn ter accuser ts l
Composita cf. C. pilula Cooper and Grant ...............--. 6
Echinauris cf. E. liumbona Cooper and Grant .............. 93

Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 1
MeckellaiskencoidesaGuty. ner eieaeciaiekeieciateni leer: 1

Neophricadothyris cf. N. crassibecca Cooper and Grant ..... 150
Neospirifer venezuelensis (Gerth) ...............scseeseeees 16
Rugatia occidentalis (Newberry) .........2 000 cece eee e ee ees I
Stauromataves CLericamn. CEN sand iSP ete: eyetetervanne et neler ats 16

BRYOZOA

indeterminate fenestellids

CORALS
(CTS)

Lophophyllidium sp.

ECHINODERMS

columnals

Although there is some disarticulation of the fossil
brachiopod shells recovered at locality 7, the large
percentage of fine micritic matrix seems to indicate
that the environment of deposition was one of rela-
tively low current energy. Most of the breakage or
distortion of shells observed can be attributed to soft-
sediment deformation, probably due to sedimentary
loading. Shells are not severely abraded: both primary
and secondary layers of most shells can be discerned
in thin-section. The abundance of angular quartz and
rock fragments suggests that the depositional environ-
ment was close to a shoreline of moderate relief, in
shallow, warm water.

Locality 8 lies in the side wall of the mule trail con-
necting Palo Quemado and Mucuchachi, about 200 m
toward Mucuchachi from a small chapel locally known
as Capilla de la Santa Cruz de Palmarito (Text-fig. 1).
This is on the old Santa Barbara de Barinas—Mucu-
chachi mule trail, within the type section of the Pal-
marito Formation as defined by Christ (1927). The vol-
ume sampled here was about one-half cubic m. The
rock at this locality had been totally leached of soluble
carbonates to a depth of over one m, so that although
the rock would texturally be a wackestone, or in com-
positional terms a biomicrite, it contained no calcite
or dolomite. Fossils from this strange matrix were re-
covered in surface collections and by cutting them
from the dried silt residues with the aid of dental tools |
and an S. S. White Airbrasive unit. Most specimens
were silicified, but many leached calcareous individ-
uals left beautifully detailed molds. These were col- —
lected if they represented rare forms or added signif-
icant features to those taxa represented by silicified
specimens. In addition to the fossils, numerous large —
bodies (up to 10 cm in largest diameter) of consoli- |
dated sediment, with thin silicified rinds, occurred —
commonly within the surrounding finer laminar sedi- —
ments. Pinching and compression of these finer lami- |
nae was probably due to loading either by these large |
clasts themselves, or by the accumulated sediment j
column, while the sediments were still relatively plas- |
tic. Among the fossils recovered were: |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 27

BRACHIOPODS
Chonetinetes cf. C. varians Cooper and Grant .............. 3
Composita cf. C. pilula Cooper and Grant ................. 76
‘DASE CDA BATE OS s.b 6 space OE CRD GOUEr a UtOe OOD De SHED oT.C l
Derbyia cf. D. complicata Cooper and Grant ............... 4
Echinauris cf. E. liumbona Cooper and Grant .............. 11
Holotricharina hirsuta Cooper and Grant .................-- 4
DMG VOTED OSS copo.chinn sosanierdadopdapsooeanecoood 1
LEMS CGH Os sooericls bodn.c0 0b DEORIOCOOR Ee HC On mt Oba tc Meret ]
Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 16
Wieekellaiskenoides | GIIty’< .fjsi2 fo ieae «oss erence Sis sss. 01sieieee peieieceys 3
Neophricadothyris cf. N. crassibecca Cooper and Grant..... 42
Neospirifer venezuelensis (Gerth) ...............0.220eeeee 1
Paucispinifera? cf. P. sulcata Cooper and Grant ........... 4
Pontisiasstenlit) Cooper and! Grant; 3. 4..22.6 0-22 +25-+ ones nec 6
INE UCT TAIN Goa sobba cosa shaeLouees Ganon onOo aoe 30
BUF LOTSA CIAIGOST ANN SP eiayelator-vonesausyeleiet oooh 2i- ctr kel eustsiose 4
Stauromata esoterica n. gen. and sp. ..........2.-.02-e0e es 3
BRYOZOA

indeterminate ramose and fenestellid forms

CORALS
(CTS)

Lophophyllidium sp. aff. L. spinosum Jeffords

ECHINODERMS

indeterminate cidaroid (echinoid) spines and plates (PMK)
columnals

GASTROPODS
(ELY)

Kinishbia sp.

Meekospira sp. indet.

Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic
New genus allied to Orthonema

PELECYPODS
(NDN)

Schizodus canalis Branson

SPONGES
(JKR)

indeterminate sponges

Soft sediment deformation in the rock at locality 8
was probably quite minor, and limited to that occur-
ring below the large bodies that are here interpreted
as storm-derived rip-up clasts. Most shell breakage
observed can be explained by either or both transpor-
tation and abrasion near the site of deposition (Text-
fig. 4). The only brachiopods at all well preserved are
those (e.g., Neophricadothyris, Composita, Derbyia)
that appear to be adapted to life on a soft substrate.
Many of the valves of Neophricadothyris however,
consist solely of beaks, suggesting that the more fra-
gile portions of the valves were abraded away. High
energy pre-depositional current or wave activity must
be invoked to account for the condition of these fos-

sils. The environment of deposition is inferred to have
been in shallow, warm water near wave base, in an
area affected by periodic storms.

Locality 10 is situated along the mule trail that con-
nects El Portachuelo and Palo Quemado (Text-fig. 1).
The rock is exposed in and on both sides of the trail
itself, about 100 m south of the house locally known
as ‘Altamira’ (owned in 1971 by Silvestre Gutiérrez).
Although several m in extent, this exposure is prob-
ably a large exotic block, as most surrounding rocks
are reddish and greenish sandstones referable to the
Sabaneta Formation. The block itself consists of rath-
er thin (S—15 cm thick) beds of a slightly silty dark
gray limestone, separated by thinner (ca. 1 cm thick)
partings of gray siltstone. The collection area covered
about two m laterally and one m normal to bedding.
Both lithologies are abundantly fossiliferous. Domi-
nant forms recognized in the field are the brachiopods
Hustedia and Derbyia. These fossils and many others
are finely silicified, and were prepared for study by
etching in dilute hydrochloric acid and removal of the
dried decalcified silt residues with an S. S. White Air-
brasive unit. Some of the globular forms (e.g., Hus-
tedia) contained silicified laminar geopetal structures.
Some cephalopods, gastropods and pelecypods were
preserved as apparent silicified micrite envelopes. In
thin-section and polished slab the rock is clearly a
biomicrite, with occasional thin bands of fine sandy
material. The shells do not appear to have been com-
pacted by soft-sediment deformation, and although the
rock is grain-supported in places, it contains a consid-
erable percentage of mud. In terms of depositional tex-
ture it is a wackestone. Some shell breakage occurred
as a result of decalcification during etching of crack-
fillings of tectonic origin. Among the fossils recovered
were:

BRACHIOPODS
ANEMONGTIa SUDIGEVISA (SINE) aes ae cerca 29
Composita cf. C. pilula Cooper and Grant ................. 5
Derbyiadeltaunicilataanespa reer eer ree erecta eeeer 34
Holotricharinat spy Av aamecet ctrl: anita ¥reeeaaree 1
Hustediathyporhachishnaspyeereeeee ee eee eee eee eS)
Pontisiasstehiis Coopemand) Grantee -eere ee ee eoere ee eerere 4
Rhynchonellaceay familyuncertainiys.-eee eee eee ae eee 5
Rugatiaintermediawns Spence dao eens eee eee 1
BRYOZOA

indeterminate ramose and fenestellid forms
“Lyropora”’ sp.
CEPHALOPODS

Mooreoceras-like orthocone nautiloid (WMF; BFG)
Martoceras subinterrupta (Krotov, 1885) (CSL)

28 BULLETIN 313

CORALS
(CTS)

Lophophyllidium sp. cf. L. pelaeum (Jeffords)
?Acaciapora sp.

ECHINODERMS

columnals

GASTROPODS
(ELY)

?Ananias sp. indet.

Apachella sp. indet.

Bellerophon sp. indet.

Euphemites aequisulcatus H. Chronic

Euphemites cf. E. exquisitus Yochelson

Glyptospira sp. indet.

Kinishbia sp.

Naticopsis sp. indet. (2 subgenera)

Onycochilus sp. indet.

Orthonema sp.

Retispira sp. indet.

“Soleniscus’> sp. indet.

Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic
Worthenia sp. indet.

New genus of high-spired gastropods

New genus of high-spired gastropods with changing spire angle

PELECYPODS

(NDN)
Pseudomonotis sp.
Sanguinolites sp.
TRILOBITES
(CKC)

Anisopyge perannulata (Shumard) Girty, 1909

The shells from this locality have suffered very little
from post-depositional soft substrate deformation. The
dark color of the rock, like that of most Palmarito
lithologies, is due to interstitial infiltration by hydro-
carbons that is clearly secondary. Although there is
some breakage and separation of the easily disarticu-
lated productids, the extremely delicate dorsal valves
of such forms as Anemonaria are often preserved in
their entirety (Text-fig. 4). This suggests that current
activity was not strong in or near the depositional en-
vironment, and that the assemblage is mostly a bio-
coenose. The attitude of many fossils (e.g., Derbyia,
Hustedia, Lophophyllidium) suggests that this locality
represents at least in part an only slightly disturbed
living assemblage. The fossil assemblage consists en-
tirely of forms adapted to life on muddy substrates,
and there are no cemented forms. The presence of
geographically widespread nektonic forms (the ceph-
alopod Martoceras subinterrupta and the Mooreocer-
as-like orthocone nautiloid) suggests that there was
access to the holomarine environment, and that local-
ity 10 lay offshore from any local reef-like develop-

ment. Most specimens of the paucispiniferid Anemo-
naria were recovered during the etching of a single
small block. This is interpreted to indicate that the
spatial distribution of such forms was discontinuous
and patchy, since postmortem transport would have
entailed more breakage and wear than is observed in
these delicate forms. Derbyia too seems patchily dis-
tributed, but not in so clear cut a manner as Anemona-
ria. Specimens of Hustedia appear discontinuously
distributed as well: some individuals of both it and
Derbyia are markedly atypical or asymmetrical, indi-
cating growth in dense populations, yet some blocks
collected contain few individuals of either. The diver-
sity of gastropod types and the presence of trilobite
remains suggest a vigorous infauna whose bioturba-
tory activities may have contributed to some of the
valve fragmentation observed. The environment of
deposition, and for most of the organisms preserved,
the life environment, is interpreted as having been in
shallow, warm water below wave base, on a soft mud-
dy bottom, with clear access to open ocean, and rel-
atively far offshore.

Locality 11 consists of several exotic blocks lying up
a steep slope from a disused mule trail that connects
the small settlhements of El Portachuelo and Santa
Rosa (Text-fig. 1). It lies on the west flank of the Que-
brada Palmar, near the head of that stream. The rocks
are repeated intercalations of thin- to medium-bedded,
dense, dark gray, petroliferous fossiliferous silty lime-
stones and thinner, fossil-poor calcareous siltstones.
The contacts between limestone and siltstone are
somewhat undulatory but are persistent as far as they
can be traced (tens of m in some of the largest blocks).
There are two distinct lithic types within the limestone
itself, which are revealed in thin-section and polished
slab: one is a relatively unfossiliferous biomicrite,
which is poorly sorted and in places laminar; the other
is a very fossiliferous muddy calcarenite, and textur-
ally is locally either a packstone or grainstone. Most
of the clasts in both rock types are skeletal in origin:
those in the grainstone are considerably more rounded
and abraded. The fossils recovered were all silicified,
many of them imperfectly. Silicified micrite envelope
casts of chiton plates, cephalopods, gastropods, and
pelecypods are common. The assemblage was pre-
pared for study by etching in dilute hydrochloric acid,
and subsequent removal of the dried silt residues using
hand tools and an S. S. White Airbrasive unit. The
asymmetry of valve distributions and general condi-
tion of the fossils indicates that there had been con-
siderable taphonomic abrasion, if not transportation.
Among the fossils recovered were:

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 29

BRACHIOPODS

Anemonaria? cf. A. sublaevis (King) ...........2-0200e005> 4
Composita cf. C. pilula Cooper and Grant ...............-- 6
Derbyia cf. D. filosa Cooper and Grant .................5-- 9
Echinauris cf. E. lappacea Cooper and Grant............... 20
NOE ARS hws ep adaoncopae ono boDmoooobmod aDcopoMe 1
PIUSICAICNILY POF RACHISAN ESD ease tier-t-\- ate steteveterasierc ict ners sera 43
Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 5
MEE KEN CASKenoid ess GiltVecrteiesy-/-\sarciteislvors tere siorchtele e etelets crcl 1
PoniusiaysteniinGooper and Grant \-)1-)- tse << ieteli< oie eteler al 17
Rhamnariidae cf. Ramavectus Sp. .......... 0 cece eee eens 1
THEO THONEAHOMG SisccosenoddesseeoosuouobbadonDoDDDO 4
Spinifrons? cf. S. grandicosta n. Sp. ... 1.00... e cece eee 7
MEXATING ACen WOrGeNsis) (KING) = yers ee ale sees eles eins ee 5
BRYOZOA

indeterminate ramose and fenestellid types

CEPHALOPODS
(WMF; BFG)

Mooreoceras-like orthocone nautiloid

CHITONS
(AGS)

indeterminate chiton plates

CORALS
(CTS)

Lophophyllidium sp.

ECHINODERMS

columnals

GASTROPODS
(ELY)

Anomphalus sp. indet.

Apachella aff. A. franciscana (Chronic)

Apachella sp.

“Colpites”’’ sp. indet.

Cylicioscapha sp.

Glyptotomaria sp. indet.

Glyptospira sp. indet.

holopeiform gastropod indet.

Kinishbia sp.

?Meekospira sp. indet.

Onycochilus sp. indet.

Orthonema sp.

Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic
Taosia sp.

new genus aff. Taosia

new genus allied to Orthonema

new genus of high-spired gastropods

open-coiled vermitiform pleurotomariacean, genus new

PELECYPODS
(NDN)

Astartella sp.

Aviculopecten sp.

Guizhoupecten sp.

Nuculopsis sp.

Parallelodon sp.

Pegmavalvula cf. gloveri Newell and Boyd
Pseudomonotis sp.

Pseudopermophorus sp.
Sanguinolites sp.
Streblochondria sp.

SPONGES

(JKR)

Colospongia sp.
Cystothalamia sp. (nov.?)
Defordia cf. densa Finks
Girtyocoelia sp.
Haplistion cf. H. aeluroglossa Finks, 1960
hexactinellid root tuft
Wewokella (?) sp.

Most specimens of the diverse fauna recovered from
this locality come from the relatively thin packstone-
grainstone layers, which consist almost entirely of se-
verely abraded skeletal fragments. Far less worn, bro-
ken or abraded shells are found outside of these layers:
the faunal composition of the muddier portions is es-
sentially the same as that in the packstones, but fossils
are far less abundant. This suggests that the more fos-
sil-rich layers are simply localized concentrations de-
rived from the same environment, the result of pe-
riodically elevated energy conditions. The silty layers
that intervene between the limestones, however, are
almost barren of fossils, and contain only an occa-
sional Hustedia or Composita, brachiopods that are
almost ubiquitous in the Palmarito (Text-fig. 4). These
siltstone laminae are interpreted as fines that have
been winnowed out of the packstone-grainstone lay-
ers. The shells found in the siltstones are probably
those generalist forms that first settled on the soft sub-
strate when the energy regime had returned to lower
levels.

The fauna as preserved is one of the most diverse
in the Palmarito, but no one element is dominant. It
appears that most of the forms have been derived from
another life environment and are here allochthonous.
Although no rip-up clasts such as those seen at local-
ities 4 and 8 were observed, some of the rocks seen
here (the packstone-grainstone layers and siltstones)
could be ascribed to the local winnowing action of
periodic storms, which would segregate the skeletal
debris and micritic matrix on the sea floor. Preserved
portions of an apparently diverse assemblage of bio-
turbators (chitons, gastropods, some pelecypods) may
have aided in comminution of skeletal debris, but can-
not be responsible for the sorting observed. The en-
vironment of deposition is interpreted as having been
in shallow, warm water, near wave base, over a soft
substrate, in an area subject to periodic storms.

Locality 13 consists of a large (ca. 100 kg) rounded
exotic block which lay beside the mule trail connecting
El Portachuelo and Mucuchachi, about 200 m toward

30 BULLETIN 313

El Portachuelo from locality 6 (Text-fig. 1). No expo-
sures of similar rocks could be located on inspection
of the surrounding area. The boulder showed no ob-
vious bedding laminations, and was a dense, dark gray
to black, petroliferous, silty limestone, without the
siltstone partings common to most other samples col-
lected in this study. In polished slab examination,
there were suggestions of bedding along which hydro-
carbon infiltration had proceeded. Thin-section ex-
amination showed the rock to be compositionally a
biomicrite, with dolomite rhombs in addition to skel-
etal clasts, and in terms of depositional texture a
wackestone. It had not been secondarily compacted
as had many other Palmarito samples, and the fossils
recovered from it were without exception exquisitely
preserved by fine silicification (see Pl. 4, fig. 55). All
recovered fossils were prepared by etching in dilute
hydrochloric acid, and removing the small quantity of
adherent silt residues using an S. S. White Airbrasive
unit. Valve distributions of some easily disarticulated
productaceans like Echinauris were markedly asym-
metrical (Text-fig. 4). This may in part be explained
by the comparative fragility of the dorsal valve in such
forms. Most other valve distributions were symmet-
rical. Among the fossils recovered were:

BRACHIOPODS
Chonetinetes cf. C. varians Cooper and Grant .............. 4
Composita cf. C. pilula Cooper and Grant ................. 8
DerbyiaiauripleXxdaneisp wert La irik ete 7
OEM Sos goossosene gob susbo po omnonooEbogbouEnAeSToEB Od 4
Echinaurisibella) Cooperand! Grant = eee se tere tere) -t=y-t)s 377
FET OLOTICRATINGESD WAG eect een senate tlaitret l
Hustediavhyporhachisans Speanai ea eae eee ala 89

OligothyrinaQvgsp were esas AN Ie eee REN els 2
SH OOO GTA NCO SOs sbeooguccssced¢oonsccvconupod de 2

BRYOZOA
indeterminate fenestellids
CHITONS
(AGS)
indeterminate chiton plates
CORALS

indeterminate solitary rugose form

GASTROPODS
(ELY)

Anomphalus sp. indet.

Apachella sp.

Discotropis sp. of Yochelson, 1960
cf. Donaldina sp. indet.
Glabrocingulum sp. indet.
Glyptospira sp. indet.

Goniasma sp. one

Goniasma sp. two

Kinishbia sp. indet.

Meekospira sp. indet.
Naticopsis sp. (new subgenus)
Orthonema sp.

Taosia sp.

?Worthenia sp. indet.
holopeiform gastropod indet.
low-holopeiform gastropod
open-coiled ?pleurotomariacean
high-spired genus indet.

new genus of high-spired gastropods
sinistral gastropod indet.

PELECYPODS
(NDN)
Sanguinolites sp.
Pseudomonotis sp.
TRILOBITES
(CKC)

Anisopyge ?inornata Girty (in Lee and Girty, 1909)

The exquisite preservation of such delicate spinose
forms as the Echinauris and Holotricharina here sug-
gests that deposition took place under conditions most
favorable for fine preservation (rapid burial in soft sed-
iment, perhaps under reducing conditions). The lack
of breakage by soft sediment compaction suggests that
the rocks were deposited close to the end of Palmarito
deposition, and that the overlying column of marine
sediments was thin. The symmetric valve distribution
(Text-fig. 4) of most faunal elements suggests that ta-
phonomic alteration was minimal. The comparative
fragility of the dorsal valve of the Echinauris easily
explains the asymmetric distribution seen in that form.
The ventral valve is protected from breakage by a for-
est of spines that almost completely surrounds it.
Muir-Wood and Cooper (1960, p. 45) suggested that
some accumulations of marginiferids (like Echinauris
here: see PI. 4, fig. 55), that included shells in almost
every possible orientation, may have been biocoeno-
ses. The spines covering the ventral valve hang over
the commissure to such a great extent that the shell
would have been supported above the soft substrate,
and able to carry on life processes in clear water, in
almost any position. It may be that the hollow, mantle-
filled spines also served as springs to cushion the jars
and blows encountered as the shells were rolled about
the sea floor by currents. The comparatively large
number of specimens of this form collected here is
probably best explained by the manner in which the
spines of Echinauris entangle one another. Obviously
this sort of habit led to localized and discontinuous
populations on the sea floor. Pre-lithification breakage
of the entire fossil assemblage at this locality was mi-
nor. The environment of deposition is interpreted as
having been a soft-substrate bottom, with little relief,
below wave base in warm water, perhaps restricted

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 3]

from ready access to open ocean conditions. The pres-
ence of chitons, gastropods, certain pelecypods and
trilobites suggests the presence of an infauna that may
in part have been responsible for any shell disarticu-
lation that occurred. Bioturbation, if present (see
Thayer, 1979), was extensive, as few traces of bedding
laminae, and no burrows or feeding traces now re-
main.

DEPOSITIONAL ENVIRONMENTS

Pierce et al. (1961) and Arnold (1966) have dem-
onstrated that the Sabaneta and Palmarito Formations
(or facies) are records of a marine transgression from
southeast to northwest across the Mucuchachi depo-
sitional basin in Permian time. The Sabaneta repre-
sents the continental facies of this transgression and
the Palmarito the marine facies. None of the rocks and
fossils analyzed here indicate deposition in other than
marine conditions, but some (locs. 3, 5 and 13) indicate
that access to open ocean may have been restricted
locally. Almost all the assemblages are characteristic
of soft, muddy substrates. In only three (locs. 3, 5 and
6) are there indications of other conditions. In the en-
vironment of locality 5, energy conditions were prob-
ably too severe to allow settlement of attached forms
on the winnowed calcarenite substrate, but at locali-
ties 3 and 6, hard-bottom assemblages colonized
sponge substrates. At locality 3, hypersaline condi-
tions may have prevented optimal development of the
full potential of brachiopod diversity provided by or-
ganic hard substrates in the Tethyan realm. At locality
6, however, holomarine conditions were present, and
greater diversity could develop. The faunal differences
in the three samples from that locality are probably
due to a variety of causes, notably the patchy distri-
bution that is characteristic of tropical organisms. The
periodic storms inferred from sediment characters in
the Upper Palmarito Formation may have acted as
environmental stresses deterrent to bioherm formation
on the scale of those seen in the age-equivalent Ca-
thedral Mountain and Road Canyon Formations of the
West Texas region.

ORGANISM/SUBSTRATE RELATIONSHIPS

Stehli (1971) suggested that in tropical regions soft-
substrate environments may act as a secondary stress,
after temperature, limiting the distribution of some
Permian Tethyan articulate brachiopods. One object
of my study was to determine if there were some ob-
jectively measurable parameter that could be related
meaningfully to the character of the substrate on
which these brachiopods lived. A measure of the size-
frequency distribution of sedimentary particles was

one logical possibility (Hoover, 1976b). The easily
measured sand/silt ratio was not employed, since in
the Palmarito the sand and coarser particles commonly
are skeletal in origin, and are variably silicified. Some
are lost in etching, so that the weight percent of re-
coverable sand is meaningless as a measure of original
sediment grain-size distribution. A potentially more
useful parameter that appeared likely to remain intact
through lithification and diagenesis was the ratio be-
tween silt- and clay-sized particles in the hydrochloric
acid-insoluble residues. The silt/clay ratio should re-
flect substrate character as a partial record of the en-
ergy regime and (or) current activity. A higher energy
regime or episodic activity should leave a lithic record
with a higher silt/clay ratio than that of a quiet envi-
ronment or episode, since higher energies would pref-
erentially remove the finer particles. The only Pal-
marito rocks useful for such studies were those that
contained appreciable numbers of silicified fossils. It
was assumed that silicification equally affected all
sizes of fine particles, so that the insoluble residues
remaining after etching would reflect in a consistent
way the size-distribution of the parent sediment. It
was also assumed that originally non-carbonate fines
were either minor, or had the same or similar size-
frequency distributions as the calcareous sediments,
and that the percentage of clay-sized particles agglom-
erating to form silt-sized particles was approximately
the same in both insoluble residues and parent sedi-
ment.

Much of the Palmarito is characterized by repeated
intercalations of thin limestones and thinner shales.
Where possible both lithic types were sampled at each
collecting locality, and analyzed separately. Analytical
techniques and calculations were discussed by Hoover
(1976a).

In most Palmarito localities an interesting result of
the analysis was that shales had higher silt/clay ratios
than the limestones they separated (see Table 5).
Everywhere that this relationship held, the shales con-
tained much less diverse brachiopod assemblages than
did the limestones. In places where this relationship
did not hold (locs. 6A and 10) the shale assemblage
was equally as diverse as that of the surrounding lime-
stone. The shales (assuming the silt/clay ratio does
indeed reflect energy conditions) are thus interpreted
as having been produced by the winnowing effect of
localized higher energy conditions. The few fossils
found within them are the most common forms (Hus-
tedia and (or) Composita), which apparently either
could live under rather harsh conditions, or were the
first to resettle the free substrate when energy condi-
tions returned to lower levels. The shale at localities

32 BULLETIN 313

6A and 10 is interpreted as the result of a change in
sedimentation rate, rather than energy conditions,
which would not change the size-distribution of the
substrate grains or materially alter the habitat of the
brachiopods that lived there. The intercalated lime-
stones and shales of the Palmarito suggest a periodic-
ity of such higher energy episodes. Ager (1974: Juras-
sic of Morocco), Bowen, Rhoads, and McAlester
(1974: Devonian of New York), and Bretsky and Bret-
sky (1975: Ordovician of Quebec) noted similar de-
posits and interpreted them as storm deposits. Tending
to support this contention for the Palmarito are the
apparent rip-up clasts seen in the limestones of assem-
blages 4 and 8 (see ‘“‘Lithic and Faunal Analysis’).

It was originally hoped that the silt/clay ratio might
be correlated with brachiopod habitat type, which
should in turn be controlled in part by substrate. To
this end, the Palmarito brachiopod genera were sep-
arated into three classes by habitat type: pediculate,
free-living and cemented (Table 6). The percentage of
the total bed assemblage in each class was calculated
(for both species and individuals) and plotted on a tri-
angular diagram (Text-fig. 5). The proper position of
some genera in this admittedly simplistic division is

Individuals

Text-figure 5.—Habitat-type distributions for species and individ-
uals in Palmarito Formation brachiopod assemblages. Localities are
numbered. F = free-living, supported on soft substrate by spines or
shell; P = attached to hard or soft substrate by functional pedicle;
C = cemented or closely appressed to hard substrate; E = entire
brachiopod fauna (all localities).

Table 5.—Results of rock constituent analyses of Venezuelan
marine Permian rocks containing appreciable numbers of silicified
fossils. See Hoover (1976a) for discussion of calculations and ana-
lytical techniques. L = limestone analysis; S = shale analysis;
Rep. = replicate analysis.

Percent Percent

Local- Soluble Insoluble % Silt/

ity and Carbonate Inorganic % Clay Silt/Clay

Gross and (sand- (insoluble Ratio
Lithol- Organic size or and (by

ogy Fraction coarser) inorganic) weight)

3, 91.9 6.7 0.9/0.5 1.86
35 49.9 48.8 1.0/0.3 3.73
4, qe 18.0 5.0/1.9 2.56
4, 66.5 253 6.6/1.6 4.64
Shy 97.5 0.5 1.1/0.9 ieil7/
6A, 89.2 6.8 2.3/1.6 1.42
6A, (Rep.) 89.8 6.5 2.1/1.6 1.27
6As 70.6 17.9 6.9/4.6 1.50
6C,, 87.4 7.9 2.9/1.8 1.65
10, 87.9 Sy 4.0/2.8 1.43
10, 65.2 22.9 5.9/6.0 0.99
11, 87.0 10.3 1.8/0.9 1.90
iil 67.5 19.6 9.3/3.6 2.56
13) 94.9 1.3 PN 1.22

questionable. Schiimann (1969) has shown that many
of the Orthotetacea, including such Palmarito forms
as Meekella and Derbyia, were not cemented to the
substrate but rather attached by a short byssus-like
pedicle, which penetrated the ventral beak through

numerous tiny holes. These two genera are here ar- ©

bitrarily assigned to the pediculate class.
Text-figure 5 emphasizes the difference in taxonom-

ic and habitat-type composition between the incipi- —

ently biohermal fauna at locality 6 and all others in the
Palmarito. As can be seen by a comparison of the silt/
clay ratios (Table 5) and the habitat-type diagrams
(Text-fig. 5), there is no correlation between the two.
Within the variation attributable to experimental error
(Hoover, 1976a), the silt/clay ratio of soft-bottom as-
semblages such as locality 10 are identical to those
from the demonstrably hard-bottom incipiently bio-
hermal assemblages of locality 6. It is difficult to dif-
ferentiate soft- from hard-bottom assemblages on se-

dimentological grounds in carbonate rocks. It appears _
that, at least in the Palmarito, hard bottom assem-
blages arise on soft substrates, by initial growth of
populations of large sponges (e.g., Defordia sp.).
These forms were able to grow, once established on |

a comparatively small hard substrate such as a shell, |

and to increase in size far beyond the margins of the |
original attachment surface. They could grow out |
along the surface of soft substrates and project upward |
into the water column as well. They thus provided |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 33

Table 6.—Habitat-type classification of Palmarito Formation bra-
chiopod genera. Pediculate = attached to the substrate by a func-
tional pedicle during most or all of life; Cemented = anchored by
ventral valve, ventral beak, or rhizoid spines, usually to some
“‘hard’’ surface; Free = lying loose on the substrate, there sup-
ported by the ventral valve, commonly also by specially oriented
spines or processes.

Pediculate Cemented Free

Acosarina? Collemataria Anemonaria

Anaptychius Cooperina Chonetinetes
Aneuthelasma Petrocrania Dyoros
Cleiothyridina Ramavectus? Echinauris
Composita Xenosteges Holotricharina
Costicrura Kutorginella
Derbyia Paucispinifera?
Hustedia Peniculauris
Meekella Rugatia
Neophricadothyris Spinifrons
Neospirifer Stauromata
Oligothyrina?

Pontisia

Spiriferellina

Texarina?

niches for several phyla of attached forms (including
several families of endemic Tethyan brachiopods)
which could not otherwise survive in a soft-substrate
environment. Thus the hard-bottom niches that many
of the Tethyan brachiopods occupy are not reflected
by measurable parameters of the sediment grain-size
frequency distribution, nor do these seem to correlate
with the distribution of the sponges, which act to es-
tablish greatly enlarged hard substrate areas.

It is instructive to compare the thermally-based lat-
itudinal distribution of Permian articulate brachiopods
to their habitat types. The Road Canyon Formation of
West Texas (roughly equivalent in age to the Palmarito
{see Biostratigraphic Correlation]) contains 34 families
of articulate brachiopods. Of these, 16 are globally
cosmopolitan, while 18 are limited mostly to low lat-
itudes. Slightly less than half of the cosmopolitan fam-
ilies are adapted to life on a soft substrate, and no
cemented forms are truly cosmopolitan in their Perm-
ian distribution. Among the Tethyan endemic families,
however, one-third are cemented in habitat-type, and
only a single free-living family is represented (in the
Road Canyon assemblages sampled). Thus the high
familial diversities recorded in many Permian Tethyan
fossil brachiopod assemblages reflect the presence of
organic hard substrates that provided the necessary
niche space for diversification.

PERMIAN RATIO

Stehli (1971, 1973) related the thermally-controlled
latitudinal taxonomic diversity gradient to the distri-

bution of families of thermally-tolerant cosmopolitan
(Boreal and Austral) and thermally-sensitive endemic
(Tethyan) Permian articulate brachiopods. He found
16 families that had been recovered from most Perm-
ian brachiopod faunas, all over the world. These he
designated Cosmopolitan Dominant families. They
were (according to the classification used in the Trea-
tise [Williams ef al., 1965]): the Schuchertellidae,
Orthotetidae, Chonetidae, Marginiferidae, Echinocon-
chidae, Buxtoniidae, Dictyoclostidae, Linopro-
ductidae, Stenoscismatidae, Rhynchoporidae, Athy-
rididae, Spiriferidae, Spiriferinidae, Bachythyrididae,
Elythidae and Dielasmatidae (Stehli and Grant, 1971,
p. 504). The difference between the number of families
of Permian brachiopods recovered from a locality and
the number of Cosmopolitan Dominant families re-
covered there, divided by the latter number, Stehli
termed the ‘‘Permian Ratio”’ for brachiopods (1970, p.
3330). This ratio was employed instead of pure diver-
sity in discussions of latitudinal diversity variations,
as it reduced somewhat the sampling bias inherent in
some of the collections, and acted as a temperature-
sensitive indicator. A value for the Permian Ratio was
calculated for each known brachiopod fauna, and plot-
ted against latitude (Stehli, Douglas and Newell, 1969,
fig. 2; Stehli, 1970, fig. 16; Text-fig. 6). Recent latitudes
are used in preference to any of several paleomagnet-
ically-based paleolatitudinal frameworks, (1) to pro-
vide direct comparison with relevant previous papers
(e.g., Stehli, 1970), and (2) to avoid the controversy
that would follow the use of any one of the paleomag-
netic schemes currently in favor (cf. Habicht, 1979;
Scotese et al., 1979). My usage of a recent latitudinal
coordinate should in no way be construed as a denial
of the sea-floor spreading and continental drift hy-
potheses. Although there is considerable spread in the
values, there is clearly a trend upward from the pole
toward a maximum close to the present equator. The
fauna of the Palmarito, as it was known prior to this
study (i.e., from Arnold, 1966; Pierce et al., 1961),
provided the data for point | in Text-figure 6.

This fauna was not included in Stehli’s figures, as
he had used only those which were described and fig-
ured, so that he might personally ascertain familial
assignments. It happened by chance that the speci-
mens on which Arnold’s faunal list had been based
came (via the identifier (Dr. H. M. Muir-Wood) and
Dr. A. J. Boucot) to be in the collections of the Na-
tional Museum in Washington, D.C. Dr. Muir-Wood’s
identification labels still accompany the specimens.
Conditions were thus ideal for a taxonomic re-evalu-
ation of the fossils (Hoover, 1976a).

Each identified brachiopod in the Arnold Collection

34 BULLETIN 313

PERMIAN

10 RATIO

80 70 60 50 40 30

LATITUDE

O
O
@O
Oy ee) O
O
O
O
O
O
SOUTH

——

A —[P
20 10 (0) 10 20 30 40

Text-figure 6.—Permian Ratio for brachiopods, calculated for well-known localities of marine Permian fossils, plotted against latitude. Point
@) represents the Palmarito fauna as reported by Arnold (1966); point @ represents that collection as re-examined herein; point ® represents
the entire suite of Palmarito Formation brachiopods available for this study. Data were derived from Stehli, 1970; Samtleben, 1971; Stehli,

pers. comm., 1973; this study.

was re-examined and identified in the light of knowl-
edge gained through study of my own collections.
Considerable generic reassignment resulted (see Table
4) and a second, revised value for the Permian Ratio
of the fauna was calculated, and plotted as point 2 of
Text-figure 6.

The classification used throughout this study is, at
the family level, very close to that of Cooper and
Grant (1972, 1974, 1975, 1976a, 1976b, 1977). In order
that the Permian Ratio values calculated for the entire
fauna might be comparable with those previously cal-
culated, the taxa presented in this study were reas-
signed at the family level, to accord with the Treatise
classification (Table 7). This third value for the Perm-
ian Ratio for Palmarito brachiopods is plotted as point
3 in Text-figure 6. One of the goals of this study was
more rigorous definition of the inflection point of the
curve in the plot of Permian Ratio vs. Latitude (see
Text-fig. 6). The addition of two or three points to the
curve cannot accomplish that. This portion of the
study shows however, that the Permian Ratio of such
tropical faunas as the Palmarito can be enhanced by

more comprehensive collecting, and that the brachio-
pod fauna, in terms of familial diversity, is Tethyan in
character, and not temperate as had been suspected
(Newell, pers. comm., 1972).

I also wanted to determine the source of the dra-
matic increase in the apparent taxonomic diversity of
the Palmarito brachiopod fauna shown in Text-figure
6. Table 8 shows Permian Ratio values for both Dr.
Muir-Wood’s and my own analyses of Arnold’s col-
lections, as well as for individual collecting localities
in the present study. It is striking that, of the twelve
non- Cosmopolitan Dominant families in the entire
fauna, eight are represented in a single locality (local-
ity 6) and that only three of these appear elsewhere in
the formation as presently known. Without the chance
discovery of this block (which probably would not
have been sampled in a normal stratigraphic study, as
it is patently out of place and not located within a
measurable stratigraphic section), the Permian Ratio
value for the entire fauna would have been drastically
reduced (see Table 8).

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

Table 7.—Familial affinities of Palmarito Formation brachiopod
genera. Both the familial assignment used in the Systematic Pa-
leontology section of this study and that used in the Treatise (Wil-
liams et al., 1965) are given. [ ] surround the probable family as-
signment of genera described since 1965. Inarticulate brachiopods
(e.g., Petrocrania) are not used in calculation of Permian Ratio or
Sampling Index.

Family in Family in

Genus this study Treatise
Petrocrania ....... (QRINGES socdsasassee Craniidae
Ascosarina? ....... Schizophoriidae ...... Enteletidae
IDERDYIG) voc cme. oven DETDYIIGACw eilreciciers- Orthotetidae
Meekella .......... Meekellidae ......... Meekellidae
DN @O9. dapaocoobeue Rugosochonetidae .... Chonetidae
Stauromata ....... Rugosochonetidae .... [Chonetidae]
Chonetinetes ...... Rugosochonetidae ....[Chonetidae]
Xenosteges ........ Aulostegidae ......... Aulostegidae
(GOOPENING .5..0-2 65: Cooperinidae ........ [Strophalosiidae]
Ramavectus? ...... Rhamnariidae ........ Buxtoniidae
Echinaurus ........ Marginiferidae ....... Marginiferidae
Echinoconchidae ... Echinoconchidae ..... Echinoconchidae
Anemonaria ....... Paucispiniferidae ..... [Linoproductidae]
Paucispinifera? . Paucispiniferidae ..... Linoproductidae
Holotricharina ..... Linoproductidae ..... [Overtoniidae]
Kutorginella ....... Retamidae™ peer eee Marginiferidae
Peniculauris ....... Dictyoclostidae ...... Dictyoclostidae
LTSEOVETE (50 ett RRR Dictyoclostidae ...... Dictyoclostidae
SPIRO GI Saae oboe Dictyoclostidae ...... Dictyoclostidae
Collemataria ...... leyttoniidael eeereeeec [Lyttoniidae]
POTS Cat eteeetneee Pontisidae eeecesceeee [Wellerellidae]
HIMSTCCIC sce... - RGWAERO soccadcopnes Retziidae
Cleiothyridina ..... Athyrididae .......... Athyrididae
Composita ........ Athyrididae .......... Athyrididae
(COSGTTIGe! Sooo ueane Ambocoeliidae ....... [Ambocoeliidae]
Neophricadothyris . Elythidae ............ Elythidae
INGOSPIFIfEr ...---- +> SIMIC S socsscaces Spiriferidae
Spiriferellina ...... Reticulariinidae ...... Spiriferinidae
Aneuthelasma ..... Dielasmatidae ........ [Dielasmatidae]
Oligothyrina? ...... Pseudodielasmatidae .. Labaiidae
Anaptychius ....... Cryptonellidae ....... [Mutationellidae]
WEXATING?) ..iviewic cs Cryptonellidae ....... (Cryptonellidae]

SAMPLING EFFICIENCY INDEX

Stehli (1970, p. 3327) and Stehli and Grant (1971, p.
504) presented as a rough measure of the efficiency of
sampling (for Permian articulate brachiopods) the ratio
of the number of Cosmopolitan Dominant families
found, to the number expected (16). It is instructive
to look at the sampling efficiency index (SEI) in com-
bination with the Permian Ratio (PR), as they are
closely related (see Text-fig. 7). This figure shows the
poor sampling efficiency in the Palmarito relative to
the intensively investigated (roughly age-equivalent)
Road Canyon Formation of the West Texas region.

A rough estimate of the advantage of silicification
over calcareous permineralization as a mode of pres-
ervation can be gained by looking at the SEI of oth-
erwise similarly constituted assemblages in the Pal-

>)
n

Table 8.—Permian Ratio and Sampling Efficiency Index of Pal-
marito Formation articulate brachiopod assemblages. Families are
assigned according to the Treatise classification (Williams ef al.,
1965; see Table 7).

Cosmo-
politan Sam-
Total Domi- pling
Number nant Perm-_ Effi-
of Fami- Fami- ian ciency
Assemblages lies lies Ratio Index
Arnold Collection
(as identified by Muir-Wood) 14 10 0.40 0.63
Arnold Collection
(as identified by Hoover) 12 9 0.33 0.56
locality 1 7 6 0.17 0.37
locality 2 1 1 0.00 0.06
locality 3 8 4 1.00 0.25
locality 4 7 6 0.17 0.37
locality 5 1 1 0.00 0.06
locality 6 11 3 2.67 0.18
locality 7 8 6 0.34 0.37
locality 8 12 8 0.50 0.50
locality 10 7 4 0.75 0.25
locality 11 11 6 0.83 0.37
locality 13 8 5 0.60 0.31
Entire Fauna 24 12 1.00 0.75
Entire Fauna 19 12 0.58 0.75
(less loc. 6)
30 r
] O,
2.04
@
e
o ° 2
104 O; eek 8 °
a eaten St @ ‘ene 8 |
PERMIAN 4 10 @ @ r
RATIO é4 (e) e e r
13 e@ Q e
4 Og r
44
| O; Qy e
24
a,
OE Pa pe RAO ERSOMMEEGOI UG70™ au aeEsO

SAMPLING EFFICIENCY INDEX

Text-figure 7—Permian Ratio and Sampling Efficiency Index for
nine Palmarito Formation (Venezuela) and 35 Road Canyon For-
mation (West Texas) articulate brachiopod assemblages. Open cir-
cles = Palmarito Formation assemblages (numbered); solid cir-
cles = Road Canyon Formation assemblages; A = Arnold collection
as re-examined herein; B = entire Palmarito Formation collection;
C = Palmarito Formation assemblages, except assemblage 6; D =
35 Road Canyon Formation assemblages.

36 BULLETIN 313

marito (Table 8; see ‘‘Biostratigraphic Correlation’’).
While it should be noted that no one locality is very
efficiently sampled, the maximum SEI attained by
silicified assemblages, such as that at locality 8 (=0.50)
is not equalled by the non-silicified assemblages (locs.
1 and 7 = 0.37), even though these were as diligently
sampled (according to a subjective estimate of effort
expended). For faunal sampling, the collection of large
amounts of silicified faunas wherever found within a
unit is superior (in terms of the SEI) to the strictly
stratigraphic attack, where samples of all exposed
rocks are taken in a single or several sections, but
along as continuous exposures as possible. In addition
to making collections of that sort, those interested in
the biostratigraphic implications of a fauna might do
well to make collections of promising float blocks. It
has been demonstrated that the SEI obtained by a
combination of these methods is superior to that ob-
tained by using a single one (my collection total SEI =
0.75; Arnold’s collection total SEI [re-examined] =
0.56).

Four Cosmopolitan Dominant Permian articulate
brachiopod families were not identified in any of the
Palmarito material available for study: the Schuchert-
ellidae, Stenoscismatidae, Rhynchoporidae and
Brachythyrididae. Rhynchopora, the only Permian
rhynchoporid genus, was reported by Pierce et al.
(1961) in the Carache area of the state of Trujillo, Ven-
ezuela, but since neither specimens, illustrations nor
descriptions were given, this occurrence cannot be
considered valid data for this study. The inherent un-
reliability of even generic identifications in faunal lists
is emphasized not only by my re-examination of the
Arnold Collection (Hoover, 1976a), but also the fact
that, to most investigators, such a list is relatively use-
less unless accompanied by the name of the person
responsible for it.

A few of the specimens from locality 6 that were
assigned to ‘“‘Rhynchonellacea, family uncertain’’ bore
some resemblance to stenoscismatids. There were,
however, no preserved interiors, or vestiges of the
anterolateral stolidium characteristic of the family, so
that not even tentative assignment to that group could
be made. The majority of the inferred substrates en-
countered in the Palmarito (soft-bottom) are inter-
preted as suitable for the establishment of populations
of stenoscismatids, so that some other factor (resulting
in nOn-occurrence, non-preservation or non-collec-
tion) must be responsible for their absence.

Although several small apparent juvenile orthote-
taceans were found at localities 3, 4 and 6, only one
appeared to exhibit the recurved erismata of the

Schuchertellidae. The small size and coarse silicifi-
cation of this single specimen, however, made even
tentative assignment to that family unjustified.

Several Tethyan brachythyridid genera are known
in the Western Hemisphere, but their occurrence is
almost entirely limited to North America. The family
is known from other continents, however, and is wide-
spread in the Boreal and Austral regions. Four genera
are known in the West Texas region: Eliva, Elivina,
Eridmatus and Spiriferella. Of these only Spiriferella
occurs in rocks of an age thought to be equivalent to
the Palmarito strata (Roadian) and there it occurs in
only two of 34 localities surveyed. Perhaps, as Grant
(1976) has suggested, connections with Boreal popu-
lations of Spiriferella were closed at this time, pre-
venting easy access to the south. In Mexico the genus
is known from the Monos Formation, thought to be a
time-equivalent of the Word Formation of West Texas
(Cooper et al., 1953). It has not been recovered further
south in the Americas, and it may be that it is not truly
cosmopolitan in its distribution.

There are several possible reasons for the apparent
non-occurrence of certain Cosmopolitan Dominant
families. Stehli and Grant (1971, p. 505, text-fig. 3;
reproduced here in Text-fig. 8) note that the SEI de-
creases southward across latitude, beginning this de-
cline at about 30° North latitude. They suggest that
this phenomenon may be due to “‘deeper tropical
weathering, less intensive study and the increase of
small, difficult to collect forms in the Tethyan assem-
blage.”’ The first of these suggested reasons at least is
not applicable to the Palmarito. Locality 8 consists of
rocks so deeply weathered that although the limestone

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204 O
UNORTAE T T a T T T T T T Tole ear Siew
90 60 30 0) 30 60 90
LATITUDE

Text-figure 8.—Sampling Efficiency Index for Permian articulate —

brachiopod assemblages, calculated for well-known collecting lo-
calities, plotted against latitude. Point ® represents the Palmarito
Formation brachiopod assemblage as reported by Arnold (1966);
point @) represents that collection as re-evaluated herein; point @)
represents the entire suite of Palmarito brachiopods available for
study. Data from Stehli and Grant, 1971; this study.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 37

depositional fabric and texture remain intact, they
contain no soluble carbonate whatsoever. Yet this lo-
cality provided the highest SEI of any in the forma-
tion, and was represented by the greatest number of
brachiopod families. Some tiny forms may have been
lost, but in the silty limestones so common in the ma-
rine Permian of Central and South America, extensive
natural leaching provides good opportunity for the for-
mation of external and internal molds. At locality 8,
some of the calcite in the specimens had been silic-
ified, so that preservation is in the form of external
and internal molds and silica replacements.

Less intensive study is a real factor: many southern
hemisphere exposures are not only relatively poorly
exposed and remote, but are far from major study cen-
ters. The high SEI’s reported to the north of 30° North
probably reflect two things. The Boreal Permian bra-
chipod fauna consists to a great extent of large, easily
recovered, commonly preserved, massive forms, due
to the proclivity (suggested by Stehli and Grant, 1971,
p. 507) for such forms to be characterized by late ma-
turity, slow growth and individual longevity, so that
faunas composed largely of Cosmopolitan Dominant
families could easily be fully sampled (16 out of 16).
Tethyan faunas from the Boreal/Tethyan boundary
down to about 30° North lie within the area where the
great majority of persons interested in the study of
such forms live, and (with the exception of Australia
and New Zealand), the combination of good exposures
and interested investigators is not present south of that
latitude. Less intensive study may also be a result of
the different modes of sampling, discussed above,
which can significantly alter both the Permian Ratio
and Sampling Efficiency Index.

In contrast to Boreal or Austral ones, Tethyan as-
semblages certainly do include smaller, more delicate
forms. Collection of silicified assemblages, however,
should (as in the Palmarito) allow recovery and rec-
ognition of the tiniest, most delicate brachiopods
(e.g., Costicrura minuta, loc. 6; see PI. 8, figs. 41, 44).

There are other possibilities. Using the Palmarito as
an example, we may compare assemblages from pres-
ent-day tropical regions to those from temperate re-
gions of the Western Hemisphere (West Texas).
Against the nearly total exposure, moderately steeply-
dipping beds and relatively high relief, and relatively
easy access and short travel distance from research
centers of the West Texas exposures, contrast the
structurally complicated, vegetatively overgrown, dis-
tant, relatively less accessible beds of equivalent age
in Venezuela. It has been suggested (McCall, pers.
comm., 1975) that the decline may be due to the equa-

torward decrease in eurytopic forms. Bulk sampling
and the use of the family as the taxonomic base should
reduce a large part of such bias.

Warme (1969) has remarked that “‘regardless of the
geometry of spacing [of samples] it is unlikely that any
sample of reasonable size will include all individual
species living in a given [tropical] habitat.’’ This of
course becomes less applicable at higher taxonomic
levels until at the family level one should be able to
sample all families present within a more modest sam-
ple size. But what is this optimum sample size? Grant
(1971) has shown that the number of species of silic-
ified brachiopods identified in the Road Canyon For-
mation of West Texas increased directly in proportion
to the amount of rock collected. He unfortunately
gives no data as to how much was collected from each
locality, but has assured me (Grant, pers. comm.,
1975) that the average exceeded the 50-100 kg range
of samples from the Palmarito. In the Palmarito it was
often impossible to sample even this much at a single
locality, due to the logistics of removing and trans-
porting that much material.

Cooper (pers. comm., 1975) has remarked that in-
dividual bioherms in the West Texas Permian tend to
have highly individual fossil faunas at the species
level, thus tending to support Warme’s contentions in
the fossil record. In the Palmarito, only locality 6
could be considered as incipiently biohermal, as con-
trasted to the commonness of these structures in the
Road Canyon Formation, its closest West Texas cor-
relative (see ‘‘Biostratigraphic Correlation’’). I sus-
pect many more as yet uncollected such deposits may
exist within the Palmarito exposures. The chance,
however, of collecting all such deposits is smaller than
that of collecting all types of biostromes or incipient
bioherms in a more accessible, better exposed situa-
tion. Thus the second of Stehli and Grant’s suggested
reasons for lowered sampling efficiency in the south-
ern hemisphere is probably largely responsible for that
decline. Although such a decline is reversible, through
intensive work and a more faunally-oriented sampling
program (see Text-fig. 8, points 1, 2 & 3), it is ques-
tionable whether that reversal would ever become fi-
nancially or physically feasible.

INTRODUCTION TO
SYSTEMATIC PALEONTOLOGY

PHILOSOPHICAL CONSIDERATIONS

The concept of the species, the basic unit of tax-
onomy, has been succinctly defined, for living organ-
isms, in terms of reproductive capability. In the fossil

38 BULLETIN 313

record, however, our frequent inability to distinguish
individual time planes confidently in the rocks often
means that rather than dealing with contemporaneous
distinct species, we are concerned with variably-sized
segments of evolving lineages. Since evolution,
whether it moves gradually or in a saltatory fashion,
is a process in which both organisms and their inter-
relationships change, the species concept becomes in-
creasingly abstract as our power of time-resolution
decreases. The most common unit of sampling in the
fossil record is the formation. Shaw (1964), among
many others, has demonstrated that formation bound-
aries may be diachronous, and that the distribution of
fossils within such a unit is not necessarily isochron-
ous. Inherent in the common belief that in paleontol-
ogy we are indeed dealing with organisms divisible
into species analogous to biological species, is the as-
sumption that the evolutionary change taking place in
a lithic unit or units is small: our gauge of this change
is, and must be morphologically based.

The paleontologist today would normally concede
that he (she) tries in some measure to think of the
fossils he studies as once-living organisms. This be-
comes a basic problem in classification: should one
attempt somehow to approximate the range of varia-
tion implied in the biological species concept, or
should one describe and differentiate morphological
variants? In the case of the Permian brachiopods one
might think there would be little choice. A vast ma-
jority of these organisms represent stocks that have
no modern representatives. Soft parts are rarely pre-
served and their form is rarely indicated. Yet the ax-
iom of the working paleontologist to “‘think of fossils
as once-living organisms’’ leads us to infer soft parts
to clothe these partial skeletons.

One possible solution to this problem would be to
give strictly morphologically-based taxa special sorts
of names. This has been done in the study of mio-
spores and ichnofossils, but, although desirable, it
seems an impractical solution to the problem faced by
the invertebrate paleontologist.

Brachiopods exhibit homeomorphy to a great de-
gree, i.e., a Mississippian and a Permian productid
brachiopod, or two geographically distant Permian
brachiopods may exhibit strikingly similar external or
internal characters. The inter-relationships of paleon-
tology and biostratigraphic and evolutionary studies,
however, may require that such forms be given dis-
tinct names that have more temporal and spatial than
morphological foundations (for a fuller discussion of
this problem, see [among others] Bell, 1950).

In sum, a morphological classification would be sim-

pler in terms of describing objects, if no further use
was to be made of them. We cannot do this because
we do envision inferential uses of fossils. We thus
make the apparently valid assumption that forms suf-
ficiently separated in time cannot represent close ge-
netic relatives (because this might suggest retrograde
evolution within a lineage, and we assume that exact
retrograde evolution is highly unlikely) and that the
conspecificity of geographically distant forms is sus-
pect. A practical justification of this assumption is bio-
stratigraphy. Genera or species with large gaps in their
temporal distributions are biostratigraphically trouble-
some.

At any time, only a limited number of brachiopod
morphologies can exist in the niches available. Tem-
poral homeomorphs, while a systematic and biostrati-
graphic problem, can be useful in making paleoeco-
logical inferences, as the they may imply adaptation
of (assumed) different stocks to similar environmental
conditions.

Morphospecies, at least species of Permian brachio-
pods described here, have different ranges of varia-
tion. In the “‘Comparison”’ sections following, each
species is carefully differentiated from others in its
genus, to justify its claim of morphologic uniqueness.
A more important reason for this intellectual exercise
is to show how closely one form may be morpholog-
ically (and, by inference, genetically) related to
another.

Species names are simply handles for convenient
discussion of time segments of evolving lineages.
More often than not, real evolutionary significance lies
with groups of several, rather than single species. As —
an entire lineage becomes better understood, specific
names as such become less significant or necessary.

FORMAT

In general the taxonomic hierarchy above the family
level is simply stated, and generally follows the clas-
sification scheme of Cooper and Grant (1972, 1974,
1975, 1976a, 1976b, 1977). Simple diagnoses of families
and subfamilies are considered sufficient here. De-
tailed generic descriptions are included only for new
taxa. Individual species are always considered in de- —
tail.

TERMINOLOGY

The jargon words peculiar to brachiopod systemat- |
ics, as for any other descriptive art, are numerous, |
and hopefully more precise than the word-combina- |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 39

tions they replace. Those used here follow Muir- Wood
and Cooper (1960), the Treatise (Williams et al., 1965)
and the recent monographic study of the West Texas
Permian brachiopods (Cooper and Grant, 1972, 1974,
1975, 1976a, 1976b, 1977).

TYPE REPOSITORIES

The initials of the type repositories cited in the fol-
lowing text are explained below:
USNM = National Museum of Natural History,
Smithsonian Institution
Washington, D.C. 20560, U.S.A.

MMH = Ministerio de Minas e Hidrocarburos (now
Ministerio de Energia)
Direccion de Geologia
Caracas, Venezuela

NMB = _ Natiirhistorisches Museum Basel

Basel, Switzerland

MEASUREMENTS

The measurements of the brachiopods presented in
the following section are standard except where oth-
erwise defined, and follow the usage of Muir-Wood
and Cooper (1960, pp. 18-20). In the tables of mea-
surements, various subscripts have been employed as
qualifications:

b = broken: Used where the shell is broken at one
or both extremities of a linear measurement. Unless
further qualified, measurements so marked should not
be taken as typical.

c = crushed: Used where complex breaks and (or)
obvious distortions of the shell, not explainable in
terms of the organism’s life processes, have occurred.
Unless further qualified, measurements so marked
should be considered atypical.

e = estimated: Used when the author has estimated
the measurement, based on reasonable restoration of
breakage, crushing or other distortion.

h = half-measurement: Used in the measurement of
bilaterally symmetrical features (e.g., hinge width of
a productid) when one extremity is damaged. The
measurement made is one-half that given in the table.

BRACHIOPOD SYSTEMATIC PALEONTOLOGY
Phylum BRACHIOPODA Dumeril, 1806
Class INARTICULATA Huxley, 1869
Order ACROTRETIDA Kuhn, 1949
Suborder CRANIIDINA Waagen, 1885
Superfamily CRANIACEA Menke, 1828

Family CRANIIDAE Menke, 1828

Discussion.—The Craniidae are the only inarticulate
brachiopods that are commonly recovered by the hy-
drochloric acid etching technique. Their original cal-
citic composition probably accounts for their silicifi-
cation in common with the articulates.

Genus PETROCRANIA Raymond, 1911
Diagnosis.—

Attached, pedicle valve thin; brachial valve conical, ornament of
concentric growth lines, in some simulating ornament of host; char-
acterized by pair of sigmoidal dorsal vascula lateralia, secondary
canals branching off laterally; posterior adductors larger than an-
terior, margin of valves not thickened. (Rowell, 1965, p. H290)

Type Species.—Craniella meduanensis Oehlert,
1888, p. 102.

Occurrence.—Petrocrania has been recovered from
rocks ranging in age from Middle Ordovician through
Permian in Europe, North America and Asia. It is un-
common in the Permian, but this is probably in part
due to lack of both interest and recognition.

Comparison.—Among Permian Craniidae, Petro-
crania differs from Crania Retzius (1781) and Phil-
hedra Koken (1889) which bear ornament of radial
costellae, Lepidocrania Cooper and Grant (1974),
which bears strongly lamellose concentric ornament
with rare spines, and Acanthocrania Williams (1943),
which bears a roughly radial ornament of short spines,
in its nearly smooth ornament of concentric growth
lines.

Discussion.—The inarticulate brachiopods play a
very small part in the total brachiopod fauna in the
Upper Paleozoic. One reason they are overlooked is
that their stratigraphic range is commonly great: as
biostratigraphic indicators they are comparatively
poor.

Petrocrania teretis Cooper and Grant
Plate 1, figures 1-6

Petrocrania teretis Cooper and Grant, 1974, p. 250, pl. 28, figs. 17—

25.
Description.—

Small, smooth, variable cones with rounded sides and anterior:
posterior side usually straight. Cones varying from nearly flat to
high and misshapen, usually low; beak off center, from one-third to
two-fifths of length from posterior margin. Posterior slope gentle;
median region somewhat swollen and having steeper sides than the
long anterior slope. Surface smooth except for slight irregularities
inherited from host. Anterior adductor scars larger than posterior
adductors which are marginal. (Cooper and Grant, 1974, p. 250)

40 BULLETIN 313

Measurements (in mm).—

Thick-
Length Width ness

LOCALITY 6, BLOCK A:

USNM 220974 (dorsal valve) Detke DPT 0.7
USNM 220975 (dorsal valve) 3h5) 38) 1.2
USNM 220976 (dorsal valve) 3.8 4.0 é
MMH-DG-501 (dorsal valve) 4.2 4.6 1.2
USNM 220977 (dorsal valve) 4.5 4.7 1.0
USNM 220978 (dorsal valve) 5.6 6.2 0.32,

LOCALITY 6, BLOCK C:

USNM 220979 (articulated valves) 3.3 3%
USNM 220980 (articulated valves) 4.3 4.5 165

Occurrence.—Petrocrania teretis Cooper and Grant
occurs in the West Texas region where it was first
described from the Cherry Canyon and Word For-
mations of Early Guadalupian age. In the Palmarito
Formation it has been recovered in the assemblages
at locality 6, blocks A and C, where it is rare. An
Early Guadalupian age for these Palmarito assem-
blages is not inconsistent with other biostratigraphic
indicators.

Diagnosis.—Small, subcircular, depressed conical
Petrocrania.

Types.—Figured Specimens: USNM 220975, USNM
220979; Measured Specimens: USNM 220974-220980,
MMH-DG-501.

Comparison.—P. teretis may be distinguished from
P. diabloensis Cooper and Grant (1974) and P. exas-
perata Cooper and Grant (1974) by its smaller size,
and from P. septifera Cooper and Grant (1974) by its
lack of a dorsal median septum. The vascula lateralia,
said by Rowell (1965, p. H290) to characterize the ge-
nus, cannot be discerned in either Venezuelan or West
Texas individuals referred to P. teretis.

Discussion.—In contrast to the long ranges and con-
sequent stratigraphic uselessness of many of the in-
articulate brachiopods, P. teretis appears to be easily
recognized by its small size and smooth exterior, and
is comparatively restricted in its time range. The spec-
imens recovered from block C of locality 6 (USNM
220979, USNM 280980) consist of articulated valves.
Although this is the first occurrence of a Petrocrania
ventral valve in the Western Hemisphere, its signifi-
cance is minor since the conjoined valves cannot
readily be separated.

Material.—
Articu- Ven-
lated Dorsal tral Type of
Locality Valves Valves Valves Preservation
6 (block A) — 11 — fine silicification
6 (block C) 2 — — fine silicification

Class ARTICULATA Huxley, 1869
Order ORTHIDA Schuchert and Cooper, 1932

Suborder ORTHIDINA
Schuchert and Cooper, 1932

Superfamily ENTELETACEA Waagen, 1884

Family SCHIZOPHORITIDAE
Schuchert and Levene, 1929

Genus ACOSARINA Cooper and Grant, 1969

Type Species.—Acosarina dorsisulcata Cooper and
Grant, 1969, p. 2, pl. 5, figs. 19-23.

Diagnosis.—Small Schizophoriidae with rectimar-
ginate to sulcate anterior commissure and low ventral
median septum.

Occurrence.—Acosarina has been recovered in the
West Texas region alone, in beds ranging in age from
latest Pennsylvanian (Gaptank Fm.) to Guadalupian
(Word Fm.). It is likely that its geographic range might
further be extended, since it probably includes many
forms previously described as Rhipidomella Oehlert
(1890) or Orthotichia Hall and Clarke (1892).

Comparison.—Acosarina is assigned to the Ente-
letacea on the basis of its punctate shell, ornament of
tubular costellae, and juxtaposition of ventral median
septum and dental plates. Among Permian genera, its
fairly wide hinge and fully developed palintropes in
both valves distinguish it effectively from Rhipido-
mella, while its short dental plates and low, elongate
ventral median septum differentiate it from Orthoti-
chia. It is distinguished from Schizophoria King (1850)
by the conservatism of internal structures in the ven-
tral apex.

Acosarina? sp.
Plate 1, figures 7-9

Description.—Small, somewhat rostrate schizopho-
riid, having relatively wide, straight hingeline, round- —
ed outline, and hollow tubular costellae. Ventral in-
terarea high, with narrow delthyrium. Ventral interior |
having dorsally directed teeth, triangular in section,
supported anteroventrally by short dental plates. Thin —
median septum arising at apex, widening and becom-
ing higher anteriorly, terminating anterior to ends of |
dental plates.

Dorsal valve unknown.

Measurements (in mm).—

Hinge Mid-

Length Width Width Height

LOCALITY 7
USNM 220981 11.0, 8.0), 10.3), 4.8.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 41

Occurrence.—The single partial ventral valve here
tentatively assigned to Acosarina was recovered from
locality 7. It was first recognized on the basis of its
tubular costellae. Its more diagnostic interior details
were later mechanically prepared.

Diagnosis.—Schizophoriid ventral valve with fairly
wide hinge, tubular costellae, short dental plates and
long, low median septum.

Types.—Figured and Measured Specimen: USNM
220981.

Comparison.—(see generic discussion) The Palma-
rito specimen is only provisionally assigned to the ge-
nus because it is unknown whether the relative
strength of dental plates and median septum in the
ventral valve were altered during preparation, and be-
cause only a single partial ventral valve was found.

Discussion.—This specimen cannot unequivocally
be assigned to Acosarina: indeed, on strictly morpho-
logical grounds, it could be ascribed to Orthotichia.
The known stratigraphic range of Orthotichia in West
Texas extends only through the Bone Spring Forma-
tion (Leonardian), while that of Acosarina in the same
area extends through the Lower Guadalupian Word
Formation. The majority of the fauna preserved at lo-
cality 7 is most similar to uppermost Leonardian
(Roadian) faunas in the West Texas area (see Table
3). In view of the great overall similarity between the
Texas and Venezuelan Permian faunas, the differing
ranges of the two genera there, and the present simi-
larity of ventral valve internal arrangements of the
Palmarito specimen to Acosarina, it is tentatively as-
signed to that genus.

Material.—
Articu- Ven-
Local- lated Dorsal tral Type of
ity Valves Valves Valves Preservation
7 — — 1 calcite permineralization

Order STROPHOMENIDA Opik, 1934
Suborder STROPHOMENIDINA Opik, 1934
Superfamily DERBYIACEA Stehli, 1954
Family DERBYIIDAE Stehli, 1954
Subfamily DERBYIINAE Stehli, 1954

Genus DERBYIA Waagen, 1884

Type Species.—Derbyia regularis Waagen, 1884, p.
594, pl. 53, figs. 1, 2, 4. Genolectotype by Hall and
Clarke (1892).

Diagnosis.—Derbyiinae having prominent single
ventral median septum directly joined near sub-pseu-
dodeltidial apex, without dental plates or spondylium.

Occurrence.—Derbyia has been recovered from
most of the world’s continents, and may be said to
have a cosmopolitan distribution in the Early Permian,
although its specific diversity is quite low in Boreal
regions. The genus is known from Mississippian
through Permian rocks, though it reaches its peak of
specific diversity in the Late Pennsylvanian and Perm-
ian.

Comparison.—The character of the ventral median
septum readily distinguishes Derbyia from other
Permian genera of the Derbyiinae. In Licharewiella
Sokolskaya (1960), the ventral median septum is con-
tinuous anteriorly with a high transverse ridge; in
Nothopindax Cooper and Grant (1974), the septum
does not reach the valve floor. Outgrowths of the den-
tal ridges onto the median septum of Derbyia may
produce a shallow secondary ‘‘spondylium,’’ which
should not be confused with the primary spondylium
of the Orthotetidae.

Discussion.—A complete and exhaustive discussion
of the history and relationships of the genus Derbyia
is presented elsewhere (Cooper and Grant, 1974, p.
289ff.), and it would be pointless to enlarge greatly
upon it here. There are, however, certain asepcts of
species assignment within the genus that must be dealt
with.

Presence or absence of secondary plications, which
has been used even in supraspecific distinctions [e.g.,
Derbyia (Plicatoderbyia) Thomas (1937)], appears in
itself to have no taxonomic significance even at the
specific level (Cooper and Grant, 1974; Cooper, 1975),
such features being present in several otherwise well-
differentiated species of Derbyia. The outline and rel-
ative dimensions (shape) are important taxonomic
features at the species level, although many species
exhibit considerable variation around a norm. Certain
species [e.g., Derbyia laqueata Cooper and Grant
(1974)] are defined as having rather wide ranges of
variation in shape. Perhaps of more widespread usage
in specific differentiation is primary surface ornament.

Ornamentation in Derbyia consists chiefly of cos-
tellae of various sizes and cross-sectional shapes. A
misleading specific character is the density of costel-
lation, which, as measured, is a gauge of both the size
and the density of packing of the costellae. An addi-
tional problem is that this feature is commonly mea-
sured in terms of number of costellae in a five mm
distance. Although the distance from the beak at
which the measurement is taken is commonly stated

4? BULLETIN 313

as well, the number of costellae reported can vary
considerably depending on the orientation of the line.

Interior details are quite variable in many Orthote-
tidina, yet may also be considered in specific diagno-
ses. This practice is only reliable when a large suite
of conspecific specimens is available for study. It fol-
lows that reliable specific identifications within the ge-
nus can only be made when suitably large collections
are available, unless the taxon is externally quite dis-
tinctive (e.g., Derbyia auriplexa, n. sp.).

Derbyia auriplexa new species
Plate 1, figures 30-36

Etymology of Name.—L. auri = ear; L. plexus =
braided.

Description.—Medium-sized for genus, thin-walled,
unequally biconvex shell; dorsal valve more convex
than ventral. Extremely auriculate, widest at hinge.
Lateral margins constricted anterior to ears, diverging
anteriorly to about midvalve; anterior commissure
rectimarginate in dorsal or ventral aspect. Definite
dorsal sulcus, arising just anterior to umbo, continuing
to anterior margin, commonly interrupted by humps
or dimples. Ornament of fine costellae (17-18 in five
mm at 10 mm distance from dorsal umbo) increasing
anteriorly by intercalation; costellae acute in section,
anteriorly sinuous. Concentric growth lines generally
absent, but strongly overlapping concentric growth la-
mellae sporadically developed, producing step-like
breaks in surface. Surface secondarily ‘‘braided,”’
with alternating humps and dimples. Costellae may
arise, die out, split or coalesce on dimples or hollows,
strengthening “‘braided”’ effect.

Ventral valve low, planar to rounded triangular in
lateral aspect, irregularly rounded in anterior aspect;
greatest height about one-fourth shell length anterior
of beak. Interarea apsacline, dorsoventrally striate,

generally low, triangular, but commonly produced
ventrally in beak area; pseudodeltidium long, narrow,
triangular in outline, rounded to flat-topped in dorsal
aspect, having smooth crest without median longitu-
dinal groove.

Dorsal valve convex in lateral aspect, convex to
bilobate in anterior aspect. Umbo low, rounded, pro-
duced slightly posterior to hingeline.

Ventral interior having strong, anteriorly directed
hinge teeth, triangular in cross-section, supported pos-
teriorly by anteriorly divergent dental ridges. Low
broad median swelling on underside of pseudodeltid-
ium, dividing secondary spondylium into two parts.
Long, thin, high median septum, scimitar-shaped in
lateral aspect, having high point at about midlength,
arising in delthyrial apex at junction of sub-pseudo-
deltidial median ridge and dental ridges, extending an-
teriorly about one-third to one-half valve length. Mus-
cle scars large, ovate, smooth to striate, without callus
rims. Interior otherwise smooth, but reflecting gross
exterior ornament of dimples and humps.

Dorsal interior having large cardinal process sup-
ported by long, thin erismata that bend slightly laterad
near dorsal ends. Low anteroventrally cuspate denti-
fers crossing entire outer faces of erismata; thin bra-
chiophores, square in lateral aspect, extending a few
mm anteriorly from erismata, just dorsal of dentifers.
Myophore bilobate, deeply cleft mesially, each lobe
having posterior median slit, internally crenulate to
denticulate distally. Chilidial plates low, disjunct, sep-
arated by deep anteroposterior groove. Dorsal inter-
area very low, having short swellings, which may
function as fulcral plates, just laterad of chilidial
plates. Low, distinct angular myophragm, flanked by
ovate, striate to flabellate muscle scars, arising below
cardinal process, continuing anteriorly about one-
fourth shell length.

Measurements (in mm).—

Height
or
Hinge Mid- Thick- Surface
Length Width Width ness Length Material

LocaLity 13

USNM 220982 27.0. 41.6y. 31.4, 15.5 — (articulated valves)

(holotype)

USNM 220983 34.5 60.0), 41.0, 14.0 50.0 (dorsal valve)

USNM 220984 34.6), 64.0), 37.6, 9.0, — (ventral valve)

USNM 220985 38.8 63.0, 38.6 19.0 57.0 (dorsal valve)

USNM 220985 45.0, 60.0), 47.0), 12.7 _ (ventral valve)

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 43

Occurrence.—D. auriplexa was recovered in good
condition only from locality 13. Several partial ventral
interareas and shell fragments with the characteristic
bumpy ornament were recovered from locality 8. A
single dorsal valve was recovered from locality 4. Lo-
calities 8 and 13 are poorly defined stratigraphically
but locality 4 is well-defined as within the Upper Lime-
stone Member of the Palmarito Formation.

Diagnosis.—Derbyia of moderate size with strongly
braided, bumpy ornament and well-defined exagger-
ated ears.

Types.—Holotype: USNM 220982; Figured Speci-
mens: USNM 220982, USNM 220983, USNM 220984;
Measured Specimens: USNM 220982-220985.

Comparison.—The only form closely related to D.
auriplexa is D. cincinnata Cooper and Grant (1974),
from the Cathedral Mountain and Road Canyon For-
mations (Leonardian) of West Texas. D. cincinnata
is in general not auriculate, and none of the specimens
of that species in the National collections shows the
uniformly extreme auriculation of the Venezuelan
form. Internal features of the two species are quite
similar, though they vary in a manner typical of the
genus. They share the characteristic external orna-
ment.

Discussion.—A Leonardian-equivalent age for the
portion of the Upper Palmarito Formation that con-
tains D. auriplexa is not inconsistent with other lines
of faunal evidence.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
4 1 1 — fine silicification
8 a — 1 fine silicification
13 1 6 4 fine silicification

Derbyia cf. D. complicata Cooper and Grant
Plate 1, figures 10-16

cf. Derbyia complicata Cooper and Grant, 1974, p. 296, pl. 81, figs.
4-38; pl. 88, figs. 1-6.

Description.—Medium-sized, small- to medium-
sized for genus, planoconvex to slightly biconvex,
quadrate, commonly auriculate shell having mesially

indented anterior margin and distinct dorsal sulcus.
Hingeline straight, commonly widest part of shell.
Surface ornament of alternating costellae and costae,
commonly one costa to every four or five costellae.
Costae best developed on visceral lobes of both
valves, absent nearer hinge and within dorsal sulcus.
Commonly seven costae on each side of dorsal sulcus
and a like number on ventral valve, a single one mesial
there. Costae and costellae crenulate, produced dis-
tally, forming crenulate and irregularly serrate mar-
gins. Costae of markedly uneven strength.

Ventral valve planar to weakly convex, with slight
to pronounced auriculation. Greatest height at or just
anterior to beak. Interarea apsacline, triangular, flat
to slightly concave, smooth to faintly dorsoventrally
striate, having triangular delthyrium apically filled by
distinct small pseudodeltidium. Pseudodeltidium
smooth, lacking median groove or prominence.

Dorsal valve moderately convex, broadly bilobate,
greatest height at about midvalve.

Ventral interior having strong, anteriorly directed
hinge teeth, triangular in section, supported posterior-
ly by distinct rounded dental ridges. Low, slender
median septum arising anterior to delthyrial apex and
extending to about one-fourth shell length. Muscle
scars indistinct, smooth, flanking median septum. Sur-
face smooth, but having deep radial furrows mirroring
external costae, extending from distal margins of mus-
cle attachment area to commissure. Anterolateral mar-
gins somewhat serrate.

Dorsal interior having small cardinal process sup-
ported by anteriorly divergent erismata; erismata
curving slightly posteriorly at distal ends. Dentifers
low, subtle, produced anteroventrally as relatively
large thin brachiophores. Myophore bilobate, cleft
mesially, with short, internally crenulate slits on pos-
terior faces of lobes, producing effective quadriloba-
tion; posteriorly U-shaped in section. Chilidial plates
comparatively large, triangular, overhanging low, nar-
row dorsal interarea posteriorly, and bases of my-
ophoral slits anteriorly. Short median keel lying be-
tween chilidial plates in median groove of cardinal
process. Surface generally smooth; many radial striae
reflecting exterior costellae. Muscle scars indistinct,
smooth, flanking low median rise that is an internal
expression of exterior sulcus.

44 BULLETIN 313

Measurements (in mm).—

Height
or
Hinge Mid- Thick-
Length Width Width ness Material
LocaLity 4
USNM 220986 12.8 19.0, 17.1 4.3 (dorsal valve)
LocaLity 8
USNM 220987 15236 26.6), 18.9, 4.5. (ventral valve)
USNM 220988 DIES 30.2, 30.3 10.7 (articulated valves)

Occurrence.—D. complicata has been recovered
only from the Cathedral Mountain and Road Canyon
Formations in the West Texas region. In the Palmarito
Formation D. cf. D. complicata is rare: a single artic-
ulated specimen and several partial ventral valves
were taken from locality 8, while a single partial dorsal
valve was found at locality 4. The Leonardian age in-
dicated by similarity of the two forms is not inconsis-
tent with other biostratigraphic indicators for those
two Palmarito localities.

Diagnosis.—Small auriculate Derbyia with strong
and unequal crenulate costellae and radial plications.

Types.—Figured and Measured Specimens: USNM
220986-220988.

Comparison.—D. cf. D. complicata may be recog-
nized best by its auriculate hinge, weakly to strongly
crenulate, uneven radial ornament, and well-devel-
oped chilidial plates. It is clearly differentiable from
other Palmarito forms of the genus: Derbyia auriplexa
n. sp. has clearly non-crenulate radial ornament with
superposed ‘“‘braiding’’ of humps and dimples; D.
deltauriculata n. sp. has more regular, non-crenulate
costellae; Derbyia cf. D. filosa Cooper and Grant
(1974) is much larger. In the West Texas collections
from which D. complicata was first described, it
seems most closely related to D. laqueata Cooper and
Grant (1974), D. texta Cooper and Grant (1974) and
D. crenulata Girty (1909). The first is admitted by its
authors to be ‘‘one of the most variable and least uni-
fied of the Glass Mountains species of Derbyia’’ (Coo-
per and Grant, 1974, p. 306). Some specimens in the
Glass Mountains share the development of primary
and secondary radial ornament, but none exhibit cren-
ulation of that ornament. D. texta is commonly small-
er and more compact that D. complicata, and its radial
ornament tends to be somewhat coarser, and compli-
cated by its more obvious concentric ornament. D.
crenulata often bears two sizes of radial ornament, but
the costae are all of roughly the same strength, in con-
trast to their uneven expression in D. complicata.

Discussion.—Vhe form of the pseudodeltidium of
the Venezuelan form is questionable; it is only pre-

served as a small triangular plate in the apex of one
of the Palmarito specimens. It may well have originally
been larger and more prominent.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
4 — 1 — fine silicification
8 1 — 3 fine silicification

Derbyia deltauriculata new species
Plate 1, figures 17-28

Etymology of Name.—Gr. delta = the Greek letter
A = an equilateral triangle; L. auriculatus = auricu-
late; eared.

Description.—Small to medium sized for genus,
thin-walled planoconvex to unequally biconvex shells
having straight hingeline and broad dorsal sulcus.
Commonly but not invariably widest at hinge; outline
semicircular, quadrate, cardioid or irregular common- —
ly modified by attachment. Shell commonly auriculate;
ears small, equilaterally triangular. Surface finely cos-
tellate (13 costellae in 5 mm at 20 mm from dorsal
beak, increasing to 18-19 in 5 mm in zones of inter-
calation), costellae commonly alternate in size, in-
creasing anteriorly by intercalation in no systematic
pattern. Costellae distinct, having straight sides and
rounded crests, of various sizes along any growth line.
Concentric ornament commonly limited to overlap-
ping lamellae, best expressed on distal portions of
valve.

Ventral valve planar to slightly convex, having api-
cal cicatrix of attachment. Greatest height at or just
anterior to beak. Beak pointed, produced slightly pos-
terior to hinge. Interarea flat to slightly concave,
smooth, with surficially undifferentiated apparent peri-|
deltidium and narrow rounded pseudodeltidium, latter
bearing consistent distinct median groove; dorsopos-'
terior surface of pseudodeltidium thus appearing bi-,
lobate. Anterior margin of pseudodeltidium straight or’

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 45

concave, with or without median salient correspond-
ing to supra-pseudodeltidial median groove.

Dorsal valve moderately to strongly convex. Ante-
rior commissure straight or slightly indented; greatest
height at about midvalve.

Ventral interior having strong anteriorly directed
hinge teeth, triangular in section. Dental ridges, nar-
rower than teeth, running from distal edge of tooth
base to delthyrial apex. Subpseudodeltidial median
ridge present, commonly produced anteriorly as sa-
lient, beyond anterodorsal pseudodeltidial margin.
Median septum long, slender, scimitar-like, highest
point commonly opposite anterior ends of hinge teeth.
Muscle scars flabellate, anteriorly raised on slight
pads, commonly with lobate rims, flanking median
septum to its anterior termination. Remainder of in-
terior surface smooth, except crenulate or radially
grooved at anterolateral margins.

Dorsal interior having relatively small cardinal pro-
cess supported by short, fragile, laterad-curving eris-
mata. Dentifers short, low. Chilidial plates disjunct,
robust, reflexed over very low dorsal interarea. Lat-
eral extensions of chilidial plates acting as fulcral
plates. Cardinal process myophore bilobate, having
short median cleft, each lobe bearing slit on posterior
face. Myophore posteroventrally U-shaped in section,
effectively quadrilobate. Low, broad, indistinct me-
dian rise, separating indistinct smooth muscle scars,
reflecting exterior sulcus. Anterior and lateral margins
radially grooved to crenulate. Remainder of interior
surface smooth to faintly striate, striae mirroring ex-
ternal ornament.

Measurements (in mm).—

Hinge Mid-

Length Width Width Height Material

Loca.iry 10
USNM 220989 — 20.2 19.2 4.0
USNM 220990 14.1 28.6, 20.0 5.1
USNM 220991 USE2) E2510) | 2220) 6:4
USNM 220992 16.5 30.8, 27.2, 4.5
USNM 220993 20.9 35.3 27.1 4.8
(holotype)

(ventral valve)
(dorsal valve)
(dorsal valve)
(ventral valve)
(ventral valve)

Occurrence.—This species was recovered only from
locality 10, where it is abundant.
Diagnosis.—Medium-sized auriculate Derbyia with
transverse outline, regular alternating straight costel-
lae and distinct broad dorsal sulcus.
Types.—Holotype: USNM 220993; Figured Speci-
mens: USNM 220991, USNM 220993-220996; Mea-
sured Specimens: USNM 220989-220993.
Comparison.—Derbyia deltauriculata n. sp. is eas-
ily distinguished from the other Palmarito species of

that genus: from D. cf. D. complicata Cooper and
Grant (1974) by its smooth costellae; from D. auri-
plexa n. sp. by its evenly costellate surface; from D.
cf. D. filosa Cooper and Grant (1974) by its small size.
The common Bolivian Permian species, D. buchi
(d’Orbigny, 1842) is easily distinguished by its more
circular outline, coarser radial ornament, and the rar-
ity of auriculation in that form. In all characters but
auriculation, D. deltauriculata closely resembles the
North American species D. crassa (Meek and Hay-
den, 1858), especially some forms from the Permian
(Wolfcampian) of Kansas. Specimens collected by G.
A. Cooper in 1953 from the Florena Shale Member of
the Beattie Limestone (USNM Acc. No. 199311) show
striking similarities to the Palmarito species. They are
not so auriculate, but are more so than the typical D.
crassa. This form, not formally identified or described,
may be intermediate between D. crassa and D. delt-
auriculata, and is easily distinguished from the several
subspecies of D. crassa erected by Dunbar and Con-
dra (1932) by its auriculation.

Discussion.—The type of D. crassa is of unknown
stratigraphic position, but specimens referred by Dun-
bar and Condra (1932) to this species are from units
in the North American mid-continent which are from
mid-Desmoinesian to mid-Virgilian in age. The speci-
mens intermediate in auriculation between D. crassa
and D. deltauriculata mentioned above are of mid-
Wolfcampian age equivalent strata. It may be that au-
riculation is a character which developed in the D.
crassa stock during the Upper Paleozoic, but there are
at present insufficient data to make more than this

suggestion.
Material .—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
10 4 26 30 fine silicification

Derbyia cf. D. filosa Cooper and Grant
Plate 2, figures 1-6

cf. Derbyia filosa Cooper and Grant, 1974, p. 300, pl. 82, figs. 1, 2,
11-36.

Description.—Large, planoconvex to biconvex
shells having straight hingeline; greatest height at or
just anterior to umbo. Outline semi-circular. Greatest
width at or just anterior to hingeline; slightly auriculate
or not. Ornament of fine costellae of roughly uniform
height, acute in section, separated by flat-bottomed
troughs. Costellae arising at beak and increasing an-
teriorly by intercalation, in four to five unsystemati-

46 BULLETIN 313

cally distributed generations; from 10 to 16 costellae,
commonly 11 to 12, in a five mm distance. Surface
may be secondarily dimpled, bumpy or braided, more
commonly distally.

Ventral valve beak asymmetrically produced and
pursed or not, having apical cicatrix of attachment that
may or may not obscure radial ornament. Interarea
flat, triangular, apsacline, anteroposteriorly faintly
striate. Convex pseudodeltidium, filling most of del-
thyrium, exhibiting smoothly concave anterior margin
and concentric growth lamellae.

Dorsal valve commonly gently, rarely strongly con-
vex, greatest height at or posterior to midvalve. Umbo
produced slightly beyond hingeline.

Ventral interior having strong hinge teeth, triangular
in section, directed anteriorly, buttressed interiorly by
long dental ridges; ridges diverging anteriorly at about
30° on inner face of interarea. Vault of pseudodeltid-
ium having low, rounded, median longitudinal ridge,
merging posteriorly with larger base of median sep-
tum. Rounded, excavate bilateral fossae (=secondary
spondylium of Cooper and Grant, 1974) formed at
junction of sub-pseudodeltidial median ridge, dental
ridges and median septum. Median septum high, thin,
extending anteriorly only to anterior margin of diduc-
tor muscle scars. Muscle scars smooth, indistinct; in-
terior surface otherwise smooth.

Dorsal interior having large cardinal process and
long thin erismata. Latter bearing low dentifers that
do not extend dorsad to hinge. Hinge sockets well-
defined by dentifers, erismata, hingeline and low broad
swelling on lateral slope of erismata anterior to den-
tifers. Lateral lobes of cardinal process joined dorsad
to broad disjunct chilidial plates. Plates, separated by
deep mesial groove, anterodorsally overhanging re-
duced dorsal interarea as thin reflexed lips. Cardinal
process myophore bilobate ventrally, lateral lobes
deeply excavate anteroposteriorly on dorsal faces;
lobes U-shaped in posterior aspect. Inner faces of
myophoral slits crenulate to denticulate, with definite
lipped rims. Large muscle field, apparently smooth or
striate and contained by erismata; may be divided by
low, rounded median ridge, in some specimens ex-
tending up onto cardinal process shaft.

Measurements (in mm).—

Hinge
Length Width Height Material
Loca.iry 11
USNM 220997 — 77.0; 15.2 (ventral valve)
USNM 220998 60.9 85.0), —_— (ventral valve)

Occurrence.—In the West Texas region where it
was first described, D. filosa has been recovered from
the Road Canyon, Word and Cherry Canyon Forma-
tions, of Late Leonardian and Early Guadalupian age.
In the Palmarito Formation it is known only from lo-
cality 11. A Late Leonardian to Early Guadalupian
age for the beds at that locality is not inconsistent with
other biostratigraphic indicators.

Diagnosis.—Large Derbyia having weak, relatively
widely spaced costellae and a strong, reflexed bilobate
chilidium.

Types.—Figured Specimens: USNM 220998221001;
Measured Specimens: USNM 220997-220998.

Comparison.—D. filosa is characterized by its flat-
tish ventral valve, strong, relatively uncrowded cos-
tellae, auriculate hinge and short plates which join the
median septum to the dental ridges. While the Pal-
marito form shares most of these characters, the
expression of the ears cannot be ascertained in the
extremely limited number of complete specimens
available, and the costellae seem uniformly weaker
than those of West Texas D. filosa. The Venezuelan
form may be distinguished from most other species of
Derbyia by its large mature size and its relatively
widely spaced costellae; its prominent bilobate re-
flexed chilidium distinguishes it from otherwise similar
forms like D. informis Cooper and Grant (1974), D.
nasuta Girty (1909) and D. pannucia Cooper and
Grant (1974).

Material.—
Articu-

Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
11 1 8 4 medium-grained

silicification
Derbyia sp.

Plate 1, figure 29

Discussion.—Specimens of both juvenile and adult
Derbyia exhibiting the diagnostic single ventral me-
dian septum, but lacking either sufficiently good pres-

ervation or adequate numbers of specimens for spe- —
cific identification were recovered from localities 3, 4, —
6 (block C) and 13. Mature specimens (beak area of ©
a single ventral valve) were found only at locality 4. _

All other material was complete or partial valves,
mostly ventral.
Types.—Figured Specimen: USNM 221002.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 47

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
3 — 2 — fine silicification
4 — 1 1 fine silicification
6 —_ — 1 fine silicification
(block C)
13 _ 3 4 fine silicification

Family MEEKELLIDAE Stehli, 1954
Genus MEEKELLA White and St. John, 1867

Type Species.—Plicatula striato-costata Cox, in
Owen, 1857, p. 568, pl. 8, fig. 7.

Diagnosis.—Meekellidae in which the dental plates
meet the floor of the ventral valve without joining.

Occurrence.—Meekella has been recovered from all
the Americas, Europe, Asia and parts of southeast
Asia. It is known from uppermost Desmoinesian to
Upper Guadalupian equivalent rocks, although its
most cosmopolitan distribution was reached in the
Lower Permian, when its range extended to the edges
of the Boreal realm (Stehli and Grant, 1970). It has not
been recovered from Africa or Australia, and it is ex-
pected that future studies will maintain its largely
Tethyan affinities.

Comparison.—Meekella is the only genus of the
Meekellidae to be recovered from the Palmarito. It
may easily be distinguished from most other meekellid
genera by the internal details of the ventral valve, and
from Niviconia Cooper and Grant (1974) by the rela-
tive conservatism of its articulatory and visceral sup-
portive apparatus.

Discussion.—Meekella is represented in the Pal-
marito by a single, variable species that is identified
on the basis of several very small suites of specimens.
Cooper and Grant (1974, p. 352) have succinctly sum-
marized one great difficulty in identification of species
of Meekella: ‘‘Species of Meekella ... are highly
variable.’ Interior details, while important for generic
differentiation, are notoriously unreliable in specific
taxonomy, since both cardinal process and dental ap-
paratus change so remarkably during the course of
ontogeny of a single individual. Exterior details used
extensively in specific identifications may be masked
Or missing in some specimens, and indeed may appear
only in certain growth stages of the animal. Taxonom-
ically significant parameters of many species of Meek-

_ ella vary over wide ranges, the norm of which is dif-

ficult to determine without the aid of a large number

of specimens. The poor preservation of small numbers
of specimens of the Venezuelan forms thus allow spe-
cific identification in only a single case.

Meekella skenoides Girty
Plate 2, figures 7-16

Meekella skenoides Girty, 1909, p. 206, pl. 30, figs. 8, 9; R. E. King,
1931, p. 56, pl. 7, figs. 6-8; Newell, Rigby er al., 1953, pl. 21, fig.
1; Cooper and Grant, 1974, p. 370, pl. 99, figs. 40-41; pl. 101,
figs. 9-13; pl. 104, figs. 1-10; pl. 108, figs. 6-10; pl. 115, figs. 1-
32; pl. 116, figs. 1-8.

Meekella difficilis Girty, 1909, p. 206, pl. 30, fig. 10 (non R. E.
King, 1931, p. 53, pl. 4, figs. 16, 17; pl. 5, fig. 1).

Description.—Medium to large-sized, small to me-
dium-sized for genus, moderately to strongly bicon-
vex, inequivalved, having high conical ventral and
bowl-like dorsal valves. Outline transversely oval to
subcircular; commonly widest at about midlength.
Hingeline short, straight; commissure rectimarginate,
serrate. Surface ornament of fine costellae (commonly
five in a one mm distance); costellae increasing ante-
riorly, commonly by intercalation, rarely by splitting.
Oblique-sided angular plicae, superposed on costellae,
arising about eight mm from dorsal or ventral um-
bones, increasing anteriorly in width and height, not
number; very rarely bifurcating, six to eight on each
flank, from 13 to 16 per valve. Plicae strongest at an-
terior margin, becoming obsolete posteriorly and lat-
erally.

Ventral valve shallow to deep, most commonly
deep, up to two-thirds as high as wide, cone-like, hav-
ing apical to subapical cicatrix of attachment; greatest
height commonly just anterior to beak. Interarea
small, high, smooth, triangular to curved triangular,
commonly symmetric in small, apparent juvenile spec-
imens, commonly asymmetric in larger, apparently
more mature individuals. Triangular delthyrium com-
pletely filled by pseudodeltidium that is laterally
bounded by striae at delthyrial margin and has a dis-
tinct rounded monticulus with mesial groove. Anterior
margin of pseudodeltidium straight, concave if broken.

Dorsal valve swollen, commonly one-half as high as
wide; greatest height at one-third to one-half valve
length from beak. Slightly auriculate, tiny triangular
ears extending as thin plates to lateral extremities of
ventral interarea.

Ventral interior having distinct median sub-pseu-
dodeltidial groove and strong, anteriorly directed
hinge teeth, supported by dental ridges. Dental ridges
strong, supported posteriorly by thin dental plates:
plates arising, keel-like, near anterior ends of teeth.
Dental plates straight, converging but not meeting be-

48 BULLETIN 313

fore contacting floor of valve; not modified, except
anteroposteriorly striate toward anteroventral extrem-
ities in larger individuals. Surface smooth, anteriorly
plicate, reflecting exterior ornament. Muscle attach-
ment field smooth, indistinct, even in large specimens.

Dorsal interior having long cardinal process that
arises normal to plane of valve. Bilobate myophore
recurved sharply posteriorly; lobes slit posterodorsal-
ly; slits arising one-half way up vertical shaft, con-
tinuing to distal end of myophore. Myophore mesially
cleft, lobes separate but closely appressed about one-
half distance up myophore. Shaft supported dorsally
by very thin erismata that diverge anteriorly at about

50° in plane defined by their anterior edges. Posterior
face of myophore grooved dorsad to cleft; mesially
cleft keel present in some specimens. Dentifers pres-
ent as comparatively large alate extensions on sides
of erismata, extending ventroposteriorly as slender,
pointed brachiophores. Proximal ends of dentifers
cleft, having fulcral plate fused to palintrope. Subcar-
dinal cavity deep, commonly smooth, having low,
rounded but distinct median ridge arising abruptly just
anterior to umbo and terminating anterior to distal
ends of erismata. Remainder of surface broadly pli-
cate, mirroring exterior ornament.
Measurements (in mm).—

Height
Hinge Maximum or Thick-
Length Width Width ness Material

Loca.irty 3

USNM 221003 7.4 6.5 10.4 6.5 (articulated valves)

USNM 221004 11.8, 6.5 12.6 Wile (articulated valves)

USNM 221005 15.4 9.1 13.1 16.5 (articulated valves)
LocaLity 4

USNM 221006 26.3, 27.6 33.5. Tee) (dorsal valve)

USNM 221007 30.3, 20.9), 32.4, 10.7 (dorsal valve)

Occurrence.—Meekella skenoides is known in the
West Texas area from the Road Canyon, Cherry Can-
yon, Word, Bell Canyon and Capitan Formations of
Late Leonardian and Guadalupian age. In the Palma-
rito Formation it is recognized at localities 3, 4, 7, 8
and 11, while a single partial dorsal valve was re-
covered in float in the Quebrada de Portachuelo (Field
No. PRH-71-VE-23). Specimens which may be refer-
able to the species were described as Meekella sp.
(Stehli and Grant, 1970 [p. 27, pl. 7, figs. 37—40]) from
the Chochal Limestone (Leonardian) of Guatemala.
The Late Leonardian or Guadalupian age of the West
Texas specimens does not contradict the ages of the
above Palmarito assemblages as based on other bio-
stratigraphic indicators.

Diagnosis.—Medium-sized to large Meekella with
strong angular plications averaging twelve in number.

Types.—Figured Specimens: USNM 221003-—221005,
USNM 221007—221011; Measured Specimens: USNM
221003—221007.

Comparison.—Meekella skenoides is characterized
by its moderate size (rarely more than 50 mm wide),
regular sharp plications arising near the beak, small
ears, separate dental plates and proportionately high

interarea. Of the species of Meekella which reach a
comparable size, only a few are similar. M. occiden-
talis (Newberry, 1861) is distinguished by its larger
size, more prominent auriculation, and more uniform- ©
ly divergent costellae. M. prionota Cooper and Grant
(1974) possesses a prominent dorsal sulcus, a feature
that is rarely observed in M. skenoides, but is never
so strongly expressed. M. skenoides attains a smaller
maximum size than does M. magnifica Cooper and
Grant (1974). Smaller individuals of M. skenoides
might be mistaken for M. attenuata Girty (1909), but
typical specimens of that species are less deep and
have fewer costae. The auriculate cardinal extremities
of M. calathica Cooper and Grant (1974) immediately
distinguish it from M. skenoides. |
Discussion.—The small maximum size attained by
individuals recovered from Palmarito locality 3 may —
in part be the result of current sorting. The species is _
here commonly found firmly attached to sponges, and |
the largest specimens are commonly quite fragmented. |
Breakage of larger specimens of this fragile thin--
shelled form would seem inevitable in a strong current!
regime.
Material.— |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 49

Articu-
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation
Field No. — 1 — fine silicification
PRH-71-VE-23

3 9 24 24 fine silicification

4 1 5 — fine silicification
7 1 — — calcite permineralization

8 — 2 3 fine silicification

11 —

— coarse silicification

Superfamily CHONETACEA Muir-Wood, 1962
Family RUGOSOCHONETIDAE Muir-Wood, 1962

Diagnosis.—Small to large Chonetacea; shell rarely
thickened; externally smooth, capillate, costellate or
lamellose, rarely rugose. Median fold and sulcus var-
iably developed; dorsal interarea may be reflexed.
Spine row at variable angles to hinge, spinules usually
developed. Median, lateral and commonly accessory
septa developed in dorsal valve. Alveolus well-devel-
oped, deep; brachial ridges prominent. Adductor scars
smooth or rarely dendritic; no accessory adductors.

Discussion.—The original diagnosis of the Rugoso-
chonetinae, of the family Chonetidae Muir-Wood
(1962), was far less comprehensive than the above.
Cooper and Grant (1974) elevated the taxon to family
rank, citing as justification the marked differences in
internal structure between the rugosochonetids and
earlier Paleozoic chonetaceans, especially in the na-
ture of the cardinal process. That family diagnosis is
here expanded to include forms like Stauromata new
genus, which, except for certain internal details, are
well within the range of variation of the Rugosocho-
netidae as previously recognized.

Subfamily RUGOSOCHONETINAE Muir-Wood, 1962

Diagnosis.—Small to moderately large, transverse,
smooth to costellate, usually having ventral sulcus;
spine row oblique; chilidium and pseudodeltidium
usually present. Ventral interior having short posterior
median septum and low, commonly anterospinose
median ridge; surface strongly papillose. Dorsal inte-
rior having deep alveolus, usually well-developed; an-
deridia commonly protuberant; median septum long;
adductors smooth; lateral regions usually strongly en-
dospinose.

Discussion.—The subfamily includes the Late Pa-
leozoic genera Rugosochonetes Sokolskaya (1950),
Dyoros Stehli (1954), Eolissochonetes Hoare (1960),
Leurosina Cooper and Grant (1975), Lissochonetes
Dunbar and Condra (1932), Mesolobus Dunbar and
Condra (1932), Neochonetes Muir-Wood (1962),

Quadrochonetes Stehli (1954), Stauromata new genus
and Sulcataria Cooper and Grant (1969). Dyoros and
Stauromata are recognized in the present collections.

Genus DYOROS Stehli, 1954

Type Species.—Chonetes consanguineus Girty,
1929, p. 409, figs. 8, 9.

Diagnosis.—Wide-hinged smooth Chonetacea with
sulcus varying from deep to barely visible, the pedicle
valve and visceral region usually strongly fringed by
spines on the anterolateral side.

Occurrence.—Dyoros to date has been recognized
only in the western United States, where it occurs in
units that range in age from Leonardian to Guadalu-
pian, although the type species, D. consanguineus
(Girty, 1929) has been reported from the Wolfcampian
Skinner Ranch Formation. A single dorsal valve
(USNM 163553) from the Chochal Limestone (Leo-
nardian) of Guatemala, described as ‘‘Neochonetes
sp.’’ (Stehli and Grant, 1970), is more properly placed
in Dyoros, on the basis of its distinct median sulcus
and internal anterior spinose fringe in the dorsal valve.

Comparison.—Dyoros differs from Leurosina Coo-
per and Grant (1975) and Neochonetes Muir-Wood
(1962) in its possession of a definite median deflection,
and from Lissochonetes Dunbar and Condra (1932) in
the stronger expression of its internal details, partic-
ularly endospines. It differs from Eolissochonetes
Hoare (1960), Mesolobus Dunbar and Condra (1932),
Quadrochonetes Stehli (1954), Rugosochonetes So-
kolskaya (1950) and Sulcataria Cooper and Grant
(1969) in its distinct anterior endospinose fringes in the
dorsal valve. Stauromata new genus, though quite
similar to Dyoros, is distinguished by its unique an-
teroventral endospinose palisades.

Discussion.—Cooper and Grant (1975) have recog-
nized three groups of species of Dyoros in the West
Texas area, to which they have assigned the rank of
subgenera: Dyoros (Dyoros), distinguished by its
strong ears and deep sulcus; Dyoros (Lissosia), dis-
tinguished by its strong ears and reduced sulcus; Dy-
oros (Tetragonetes), distinguished by its reduced ears,

nearly vertical sides and strong sulcus. Although the
form of Dyoros here described is closest to D. (Tet-
ragonetes), it is felt that an unequivocal assignment of
the Venezuelan forms to a particular subgenus of Dy-
oros is unwarranted.

Dyoros acanthopelix new species
Plate 2, figures 17-26

Etymology of Name.—Gr. akantha =
pelyx = bowl.

Description.—Small, rectangular to transverse au-
riculate shells having straight hingeline and small tri-
angular ears. Commissure rounded rectangular to
semicircular in outline; not straight anteriorly, com-
monly having very broad dorsal fold and ventral sul-
cus. Well-preserved surfaces smooth, some poorly
preserved, slightly decorticated individuals having ra-
dially disposed taleolar traces. Concentric growth
lines not conspicuous in early growth stages; overlap-
ping lamellae often present in later shell accretions.

Ventral valve convex, having greatest height near
midvalve. Three to five posterolaterally directed hinge
spines, oriented at about 30° to hinge on either side of
low beak. Interarea low, apsacline, slightly concave,
faintly dorsoventrally striate. Narrow, crescentic,
hood-like pseudodeltidium filling apex of small trian-
gular delthyrium.

Dorsal valve concave to planar. Interarea very low,
commonly one-half height of ventral interarea, ana-
cline to hypercline. Chilidial plates disjunct, covering
portions of exterior sides and base of myophore.

Ventral interior having short ventrolaterally direct-
ed hinge teeth, unsupported by dental plates. Rounded
to subcircular boss-like thickening of posteriormost
median septum bearing two or more vertical grooves
corresponding in position to lobes of myophore. Me-
dian septum narrow, bladelike anteriorly, thicker and
higher near midvalve, there bearing stout endospines
or tubercles on crest. Septum commonly ending short
of anterior margin. Diductor scars oval, longitudinally
striate or smooth, anterolaterally bounded by large
endospines; spines apparently set on low rounded
ridge or platform, reflecting form of brachial ridges of
opposite valve. Inner surfaces of anterior and lateral
margins and ears covered by numerous small pustules,
in radial rows nearer margins.

Dorsal interior having short, stout cardinal process,
supported by thin outer socket ridges, broad inner
socket ridges and broad anderidia. Anterior margins
of outer socket ridges diverging slightly from hinge-
line. Inner socket ridges straight, widening anterolat-
erally. Cardinal process shaft short, thick; myophore
bilobate, effectively quadrilobate, each lobe mesially

thorn; Gr.

BULLETIN 313

striate on posteroventral surface. Median septum thin,
arising from junction of anderidia just anterior to deep
submyophoral alveolus, continuing anteriorly just be-
yond midvalve, there thickened and commonly bear-
ing small tubercles on crest. Broad anderidia arising
from beneath inner socket ridges, extending antero-
laterally to near midvalve, terminating in cluster of
distally oriented endospines. Smaller endospines cov-
ering area with low rounded brachial ridges that ex-
tend anteriorly and laterally to valve margins. Brachial
ridges indistinct, some marked by narrow zone of en-
dospines arising at deep hollow between inner socket
ridge and anderidium, spines increasing in size as
ridges curve around just anterolateral of anterior end
of median septum.
Measurements (in mm).—

Hinge Mid- Thick-
Length Width Width ness
LocaLity 2
USNM 221012 3.5 Salty 4.4 1.0
USNM 221013 5.0 Te] 6.9 1.3
USNM 221014 5.0 8.2 7.6 1.1
USNM 221015 Sal 6.5 6.4, 1.6
USNM 221016 a2 7.4, 6.6 1.4
USNM 221017 5.8 7.8, 8.0, 233
USNM 221018 5:9 10.8, 8.4 1.2
USNM 221019 6.0 8.8, 8.0 1.6
USNM 221020 6.2 8.8 8.5 1.6
USNM 221021 6.3, 10.4, 9.9 E7/
USNM 221022 6.9 10.2 9.3 Ne7/
USNM 221023 Ue? 10.5 93 2.1
USNM 221024 Hell 10.8), 10.0 2:9)
USNM 221025 7.8 11.0), 10.9 1.9
(holotype)
USNM 221026 OF 11.7 12.5 3.3
USNM 221027 9.1, 12.1, 11.4, 2.9
USNM 221028 9.2 11.3 11.2 3.0
USNM 221029 9.4 14.7), 13.1 3.3
USNM 221030 9.5 14.3 12.9 2.3
USNM 221031 9.5 13.6, 14.6 3.2
USNM 221032 10.5 17.8 IS) 7 3.7

Occurrence.—Dyoros acanthopelix appears in the
present collections only at locality 2.

Diagnosis. —Medium-sized, thin, quadrate Dyoros
having strongly endospinose ventral interior and
strongly tuberculate anteriorly elevated ventral medi-
an septum.

Types.—Holotype: USNM 221025; Figured Speci-
mens: USNM 221012, USNM 221019, USNM 221025,
USNM 221026, USNM 221031, USNM 221033-
221035; Measured Specimens: USNM 221011—221032.

Comparison.—Dyoros acanthopelix is easily distin-
guished from the other Palmarito chonetaceans: from
Stauromata esoterica n. gen. and sp. on the basis of

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 51

its smaller size, less pronounced fold and sulcus de-
velopment, and the striking interior details of the latter
form, and from Chonetinetes cf. C. varians Cooper
and Grant (1975) on the basis of the squarer outline,
more globose form and more conservative ventral in-
terior exhibited by that form.
D. acanthopelix may be distinguished from many of
the other species of the genus on the basis of its au-
riculate, but not acuminate or alate outline. These in-
clude D. (Dyoros) angulatus Cooper and Grant
(1975), D. (Dyoros) attenuatus Cooper and Grant
(1975), D. (Dyoros) endospinus Cooper and Grant
(1975). D. (Dyoros) extensiformis Cooper and Grant
(1975), D. (Dyoros) extensus Cooper and Grant
(1975), D. (Dyoros) intrepidus Cooper and Grant
(1975), D. (Dyoros) hillanus (Girty, 1909), D. (Dy-
oros) robustus Cooper and Grant (1975), D. (Dyoros)
transversus Cooper and Grant (1975) and D. (Lisso-
sia) vagabundus Cooper and Grant (1975). It may be
differentiated from all species of Dyoros except D.
(Dyoros) magnus Stehli (1954), D. (Dyoros) planiex-
tensus Cooper and Grant (1975), D. (Dyoros) tenuis
Cooper and Grant (1975), D. (Lissosia) parvus Coo-
per and Grant (1975) and the species of D. (Tetrago-
netes) on the basis of its quadrate form, and from D.
(Dyoros) magnus and D. (Tetragonetes) giganteus
Cooper and Grant (1975) on the basis of its smaller
size. It may be distinguished from D. (Dyoros) con-
sanguineus (Girty, 1929), D. (Dyoros) convexus Coo-
per and Grant (1975), D. (Dyoros) vulgaris Cooper
and Grant (1975), D. (Lissosia) concavus Cooper and
Grant (1975), D. (Tetragonetes) auriculatus Cooper
and Grant (1975), D. (Tetragonetes) quadrangulatus
Cooper and Grant (1975), D. (Tetragonetes) solidus
_ Cooper and Grant (1975), D. (Dyoros) subliratus (Gir-

ty, 1909) and D. (Tetragonetes) subquadratus Cooper
and Grant (1975), on the basis of its profile: thinner
| than those deeper, more globose forms. It is distin-
| guished from all other species of Dyoros in the ex-
_ traordinary development of ventral endospines. These

are arranged in dense patches anterior to the adductor

muscle field and along the crest of the enlarged, an-

teriorly elevated median septum. D. (Dyoros) endo-
_spinus also has large ventral endospines, but in that
_ form the spines are located more posteriorly, and are
| much longer and thinner than those in D. acantho-
pelix. D. (Dyoros) transversus also exhibits exagger-
_ ated endospinose development in its ventral valve, but
_ the spines in that form are located along the boundary
between the visceral cavity and the ears, instead of
| anterior to the muscle fields, as in D. acanthopelix.
D. (Tetragonetes) strigosus Cooper and Grant (1975)
exhibits random scatterings of endospines anterior to

the ventral adductor field, but no distinct elevated or
tuberculated ventral median septum.

Of the three subgenera of Dyoros proposed by Coo-
per and Grant, D. acanthopelix is probably most
closely allied to species of D. (Tetragonetes). Two
diagnostic characters of that group in the West Texas
region are the lack of strong endospines and the de-
velopment of a strong sulcus in the ventral valve.
Since the first of these criteria clearly is not satisfied
and since the second is difficult to ascertain, due to
the dorsoventral crushing common in individuals from
locality 2, I have placed the new form within the genus
Dyoros (sensu lato).

Discussion.—Specimens of D. acanthopelix in sev-
eral ways foreshadow individuals of Stauromata eso-
terica n. gen. and sp. The clusters of endospines on
the ventral valve floor anterior to the adductor attach-
ment scars in D. acanthopelix could, through the
course of ontogeny, develop into the comparatively
massive anteroventral endospinose palisades seen in
S. esoterica. Since, however, there is no direct evi-
dence to indicate the comparative immaturity of any
of the forms herein assigned to D. acanthopelix, such
suggestions cannot be formalized to the extent of in-
cluding one form in the synonymy of the other.

Material.—

Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
2 85 34 35 calcite permineralization

(fluoritized in
preparation)

Genus STAUROMATA new genus

Etymology of Name.—Gr. stauromatos = pali-
sades.

Description.—Slightly to highly concavo-convex
transverse shell having straight hingeline, strong ven-
tral sulcus and broad dorsal fold. Outline symmetri-
cally trapezoidal, sides tapering anteriorly. Commis-
sure W-shaped in ventral aspect, straight in anterior
aspect. Beak low; hinge spines at low angles to hinge.
Shell smooth to faintly capillate; finely pitted if de-
corticated.

Ventral valve convex, greatest height at or just pos-
terior to midvalve. Interarea low, wide, apsacline.
Hood-like crescentic pseudodeltidium filling small tri-
angular delthyrium.

Dorsal valve moderately concave, greatest depth
near mid-valve. Lateral margins reflexed dorsally,

52 BULLETIN 313

sloping to planar ears. Interarea anacline, reflexed; tri-
angular secondary interarea present. Chilidial plates
conjunct, smooth. Small, spinelike chilidial boss pro-
truding dorsally beyond interarea.

Ventral interior having small anteriorly directed
hinge teeth, triangular in section. Delthyrial apex filled
by boss-like secondary shell material, median boss
merging anteriorly into median septum. Septum con-
tinuing anteriorly, merging into median ridge. Smooth
posterior adductors, dendritic anterior adductors.
Deeply excavate apparent diductor attachment scars,
fringed mesially and posteriorly by high anterodorsally
directed palisades of coalesced endospines.

Dorsal interior having inner and outer socket ridges
and strong anderidia. Anderidia anteroventrally free,
terminally endospinose. Alveolus deep. Adductors
smooth. Thin median septum arising anterior to alveo-
lus, broadening anteriorly. Apparent marginal rim of
coalesced endospines around visceral disk.

Type Species.—Stauromata esoterica new species.

Diagnosis.—Rugosochonetinae having deeply ex-
cavate apparent ventral diductor attachment scars,
fringed by palisades of coalesced endospines.

Occurrence.—Stauromata new genus is known
only from the Palmarito Formation, at localities 1, 4,
7 and 8.

Comparison.—Stauromata is externally homeo-
morphous with many species of the genera Choneti-
nella Ramsbottom (1952) and Dyoros Stehli (1954), but
its exaggerated internal characters serve to clearly dif-
ferentiate it from either of those genera. Of the two,
it is probably more closely related to Dyoros, but the
striking palisade-like development of coalesced en-
dospines is thought sufficient to warrant a new generic
designation.

Discussion.—Specimens of Stauromata from local-
ities | and 7 were first erroneously assigned to Cho-
netinella, on the basis of external characters, although
this assignment was not formalized through publica-
tion. Later preparation revealed the internal features
that allowed recognition of the greater similarity to but
clearcut difference from, the genus Dyoros.

Stauromata esoterica new species
Plate 2, figures 33-37; Plate 3, figures 1-25;
Plate 4, figures 1, 2

Etymology of Name.—Gr. esoterikos = inside.

Description.—Small to medium-sized, average-sized
for genus, slightly to highly concavo-convex, trans-
verse shell having straight hingeline, strong ventral sul-
cus and dorsal fold. Outline symmetrically trapezoi-

dal, sides tapering anteriorly. Commissure W-shaped
in ventral aspect, straight in anterior aspect. Beak low,
flanked by five to seven spines that lie at low angles
to hingeline. Shell faintly capillate, finely pitted if de-
corticated. Pits rounded to radially elongate, randomly
scattered, in radial rows, or in radial and concentric
rows.

Ventral valve convex, greatest height at or just pos-
terior to midvalve. Visceral lobes high, rounded, di-
verging anteriorly at about 30°, intervening sulcus aris-
ing just anterior to beak. Interarea low, wide,
apsacline. Hood-like crescentic pseudodeltidium fill-
ing small triangular delthyrium.

Dorsal valve moderately concave, greatest depth
near midvalve. Sharp median fold arising one-fourth
shell length anterior to beak. Lateral margins reflexed
dorsally, sloping to planar ears. Interarea anacline,
reflexed; triangular secondary interarea present. Chi-
lidial plates conjunct, smooth. Small spinelike chilidial
boss protruding dorsally beyond interarea.

Ventral interior having small anteriorly directed
hinge teeth, triangular in section; entire beak and in-

terarea supported by low rounded swelling originating ©
in delthyrial cavity and running below interarea to-—

ward lateral extremities. Delthyrial apex filled by boss-

like secondary shell material; median boss merging |

anteriorly into broad median septum. Septum continu-

ing to anterior margin of adductors, at about one-—
fourth shell length, there becoming thin, blade-like

median ridge, extending almost to anterior margin.
Posterior adductors small, ovate, smooth, covering
lateral surfaces of posteriormost median septum on

slightly thickened shell plate, lapping slightly onto

valve floor. Anterior adductors ovate to triangular,
dendritic to cuspate, on slightly raised portions of
valve floor, lapping onto median septum. Apparent
diductors deeply excavate, striate; fringed by palisade

of coalesced endospines. Remainder of surface finely

papillose, granulose to endospinose; endospines stout-

er anterior to end of median septum, on radial ridges’

nearer lateral margins.

Dorsal interior having narrow outer and broad inner
socket ridges; long, strong, anteroventrally free and
endospinose anderidia. Cardinal process myophore
quadrilobate. Alveolus deep, steep-sided posteriorly,
gradually sloping anteriorly. Dorsal adductors small,

smooth. Thin median septum arising a short distance

anterior to alveolus, broadening anteriorly, terminat-
ing short of anterior margin in cluster of endospines..
Apparent marginal rims of coalesced endospines
around visceral disk, gradually sloping mesially,
abrupt distally. |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

Measurements (in mm).—

Hinge Mid- — Thick-
Length Width Width ness
LocaLity 4
USNM 221036 11.0 21.0 13.0 4.5 (ventral
valve)
Loca.ity 1
USNM 221037 11.6 DHES® 17/59/ 4.7.
LOcALITy 7
USNM 221038 11.3 20.0 17.6 4.8.
USNM 221039 11.4 20.8 16.4 4.8.
USNM 221040 11.8 20.0 16.5 5.0,.
(holotype)
USNM 221041 12.6 19.0 16.7, 5.6
USNM 221042 14.1 20.5 17.6 7.4,

Occurrence.—as for genus.

Diagnosis.—as for genus.

Types.—Holotype: USNM 221040; Figured Speci-
mens: USNM 221036, USNM 221039, USNM 221040,
USNM 221043-221045; Measured Specimens: USNM
221036-221042.

Comparison.—Stauromata esoterica is the only
known species of the genus. It may, however, be
closely related to species of the genus Dyoros, espe-
cially D. acanthopelix n. sp., which resembles an hy-
pothetical immature form of S. esoterica. No speci-
mens of §. esoterica were recovered in which the
endospinose development was not fully expressed. D.
acanthopelix, with its ventral valve lined by endo-
spines, would make a suitable precursor to S. esoter-
ica. Since they do not occur together, however, no
suggestion of more than chance resemblance can be
made at this time.

Discussion.—Very few of the present specimens of
_S. esoterica were silicified. Ordinary mechanical prep-
aration with a needle failed to delineate sufficiently the
internal features of the new form. In order to clarify
the relationships of internal structures in both valves,
twenty serial acetate peels of a single set of articulated
valves (USNM 221045) were made. Instead of being
oriented in the usual fashion, normal to plane of com-
missure, the sections were made parallel to the com-
missural plane. This was done so that finished sche-
‘matic reconstructions could simulate conventional
interior views of the valves. An attempt, largely suc-
cessful, was made to keep a 0.15 mm spacing between
successive sections. The peels were projected, at 10x
magnification, onto 1.5 mm thick sheets of Plexiglas,
using a photographic enlarger, and pertinent details

inked thereon. Using reference marks to ensure their
|
|

tn
Ww

proper juxtaposition, a stack of sections were bolted
together and photographed in stereo, to give an illu-
sion of depth to the reconstructions. The peels, mag-
nified x2, and the schematic reconstructions of both
valve interiors, magnified x4, are presented as Plate
3. Although not all interior details are clear, one may
distinguish the endospinose anterolateral fringes and
median septum of the dorsal valve, and the palisade
development of the ventral valve. In addition, it is
readily apparent that the laterally expanded distally
endospinose anderidia of the dorsal interior extend
posterior to the ventral palisades. Whether this jux-
taposition is an artifact of taphonomic crushing, or
represents an operational life relationship is unknown.
It seems likely that the combination of dorsal and ven-
tral endospines formed an impressive barrier across
the posterior portion of the valve. The function of this
barrier might be speculated upon a great length. One
obvious possibility is that of a structure to control and
direct incurrent and excurrent flow. Another possible
function might be body wall and (or) lophophore sup-
port. Arguments in favor of one or another of these
possibilities should probably wait until the study of
additional sections clarifies the relationships of the
various structures observed.

Material.—
Articu-
Local- lated Dorsal Ventral Type of

ity Valves Valves Valves Preservation

1 4 = 5 calcite permineralization
4 — — 1 medium silicification

1 14 — 2 calcite permineralization
8 — 2 medium silicification

Subfamily CHONETINELLINAE Muir-Wood, 1962
Genus CHONETINETES Cooper and Grant, 1969

Type Species.—Chonetinetes reversus Cooper and
Grant, 1969, p. 4, pl. 3, figs. 1-7.

Diagnosis.—Small, wide-hinged Chonetacea having
the fold and sulcus best developed in the umbonal re-
gion and with subconical mounds of taleolae on each
side of the visceral region toward the anterolateral
margins.

Occurrence.—Species assigned to the genus are
known, to date, from the Road Canyon and Bell Can-
yon Formations (uppermost Leonardian and Upper
Guadalupian) of the West Texas area.

Comparison.—Chonetinetes is easily distinguished
from Chonetina Krotov (1888), by its smooth exterior
and single median septum. It differs from Chonetinella
Ramsbottom (1952) in its smaller size and its incom-

54 BULLETIN 313

plete ventral sulcus, which becomes weaker anterior-
ly.

Discussion.—This report constitutes the first known
occurrence of the genus in South America.

Chonetinetes cf. C. varians Cooper and Grant
Plate 2, figures 27-32

cf. Chonetinetes varians Cooper and Grant, 1975, p. 1285, pl. 477,
figs. 54-S8.

Description.—Small, medium-sized for genus, con-
cavo-convex, auriculate rugosochonetids having semi-
circular to subquadrate outline; widest at hinge. Sides
sloping, width slightly greater than length. Surface ap-
parently smooth, pseudo-costellate when decorticated
(pseudo-costellae numbering eight in 1 mm distance at
about midvalve). Very slight dorsal fold and ventral
sulcus. Commonly six hinge spines on either side of
beak.

Ventral valve high to globose, greatest height at
about midvalve. Lateral commissure having slight dor-
sad flexure just anterior to well-defined ears. Interarea
low, wide, apsacline.

Dorsal valve concave, having dorsad flexure just
anterior to ears; lowest point mesial. Interarea re-
flexed, anacline to hypercline.

Ventral interior having large, anteriorly directed

hinge teeth, triangular in section, unsupported by den-
tal plates. Boss of callus shell material, anteriorly
rounded, filling delthyrial apex, merging ventrally and
anteriorly into short median ridge. Ridge low, rather
broad, notched where it meets valve floor, continuing
anteriorly to about one-third valve length as low me-
dian myophragm, dividing well-defined, inset, ovate,
smooth to striate muscle attachment scars. Remainder
of surface finely papillose, papillae in radial rows near-
er margins.

Dorsal interior having mesially slit, quadrilobate to
hexalobate cardinal process myophore, subcircular in
posterior aspect, lateral and ventral lobes posteriorly
slightly cuspate. Slight chilidial boss as spinelike pro-
trusion from dorsal extremity of myophore. Deep,
well-defined submyophoral alveolus. Hinge sockets
deep, well-defined by small, swollen outer socket
ridges and large laterally widening inner socket ridges
that diverge slightly from hingeline. Anderidia distinct,
low, anteriorly bearing a few stout endospines. Me-
dian septum arising at alveolus, continuing anteriorly
as low rounded ridge, becoming narrower and more
marked opposite and anterior to ends of anderidia, ©
ending at or slightly anterior to midvalve. Muscle at-
tachment scars indistinct. Remainder of surface finely ©
papillose, radially striate where decorticated.

Measurements (in mm).—

Height
Hinge Mid- or Thick-
Length Width Width ness Material

LOcALITy 4

USNM 221047 5.5 10.2 73 2.3 (articulated valves)

USNM 221049 6.0. 10.8h¢ 9.0, Dall (ventral valve)

USNM 221053 6.6 10.2, 7.0, 2.5 (ventral valve)
LocaLity 8

MMH DG-S508 5.0, 8.0, 7.0 2.0 (articulated valves)

USNM 221048 6.0 10.0 8.0 PHD) (articulated valves)

USNM 221051 6.5 9.6 Tee 2.0 (ventral valve)
Loca.ity 13

USNM 221046 PUSS 5.0 35) 0.8 (ventral valve)

USNM 221050 6.2, 11.4 8.4, Pes (ventral valve)

USNM 221052 6.5, 10.2, WSs DT (ventral valve)

USNM 221054 8.2 13.8, 9.7 3.0 (dorsal valve)

USNM 221055 8.3, 12.2 7.6. 5 (ventral valve)

Occurrence.—Chonetinetes cf. C. varians has been
recovered from localities 4, 8 and 13 in the present
collections from the Palmarito Formation. In the West
Texas area, C. varians is known only from the three
lower members (Hegler, Rader and Lamar) of the Bell
Canyon Formation (Late Guadalupian), though the in-
dividuals most similar to the Venezuelan specimens
are limited to the Hegler Member. This age is younger

than that obtained from other parts of the fauna at.
those localities. |

Diagnosis.—Small, moderately convex Choneti-
netes, resembling C. varians Cooper and Grant (1975)
but lacking the strong ventral sulcus of that species. |

Types.—Figured Specimens: USNM 221048, USNM.
221051, USNM 221056; Measured Specimens: USNM_
221046—221055, MMH DG-S08. |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 55

Comparison.—Chonetinetes cf. C. varians is easily
distinguished from all other Palmarito chonetaceans
by its concavo-convex form, its smaller size and far
more conservative interiors. Sfauromata esoterica n.
gen. and sp., is larger, less globose, and has a more
endospinose interior. The same may be said for Dy-
oros acanthopelix n. sp., although the interior orna-
ment of that form is not so striking as that of S. eso-
terica. It is more difficult to distinguish it from West
Texas species of Chonetinetes.

C. varians may be distinguished from C. angusti-
sulcatus Cooper and Grant (1975) on the basis of the
very small size and narrow ventral sulcus of the latter.
It may theoretically be distinguished from the type
species of the genus, Chonetinetes reversus Cooper
and Grant (1969), by having a strong ventral sulcus.
Most of the West Texas specimens assigned to C. var-
ians do have such a feature, but some, including a
figured paratype of the species (USNM 153677b) do
not. Specimens from locality 732a [Hegler Member of
the (Capitanian) Bell Canyon Formation] consist in
part of essentially asulcate forms, of which the cited
paratype is one. In these asulcate forms the dorsal
valve does not exhibit the subconical taleolar mounds
flanking the median septum that are supposedly char-
acteristic of the genus. It is these atypical forms that
are here identified with the Palmarito specimens, not
the majority of more typical West Texas C. varians.

Discussion.—Since the characters of minor sulca-
tion and dorsal valve interior conservatism are best
expressed in the earliest representatives of the
species, it would be tempting to suggest that they rep-
resent a genetic variant, perhaps worthy of a new spe-
cific designation. C. varians is, however, such a rare
form, that no such conclusions can confidently be
drawn.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
4 1 — 2 fine silicification
8 2 1 1 fine silicification
13 — 2 4 fine silicification

Suborder PRODUCTIDINA Waagen, 1883
Superfamily AULOSTEGACEA
Muir-Wood and Cooper, 1960

Family AULOSTEGIDAE Muir-Wood and
Cooper, 1960

Subfamily ECHINOSTEGINAE
Muir-Wood and Cooper, 1960

Genus XENOSTEGES Muir-Wood and Cooper, 1960

Type Species.—Xenosteges adherens Muir-Wood
and Cooper, 1960, p. 112, pl. 10, figs. 1-13.

Diagnosis.—Nearly smooth Aulostegidae, generally
of small size, having rhizoid spines only and promi-
nent, commonly elevated brachial ridges and dorsal
adductor scars.

Occurrence.—Several species of Xenosteges are
known from the West Texas area in rocks ranging in
age from Late Wolfcampian to Late Guadalupian
(Capitanian). Two specimens questionably assigned to
the genus have been reported from Thailand (Water-
house and Piyasin, 1970) in rocks correlated to the
Cathedral Mountain Formation of the West Texas area
(Grant, pers. comm., 1974).

Comparison.—Xenosteges is easily distinguished
from other genera of the Echinosteginae by its total
lack of ornament spines, all spines being of rhizoid
habit and involved intimately in the attachment of the
shell to the substrate. Strophalosiella Likharev (1935)
lacks ornament spines as well, but it is finely costellate
on both valves, while Xenosteges is lamellose to
weakly rugose. Xenosteges may be distinguished from
the similarly aspinose strophalosiid genus Heteralosia
R. H. King (1938) by the presence of teeth and sockets
in that form. It is distinguished from another small
aulostegacean, Atelestegastus Cooper and Grant
(1975), by the consistently narrower hinge and fine
ornament spines of that form.

Discussion.—Xenosteges, by virtue of its total lack
of ornament spines and its lamellose to weakly rugose
ornament should be readily recognizable in Permian
faunas. One obstacle to this recognition may be its
small size. If the Thai specimens are indeed improp-
erly assigned to the genus, its absence outside the
Western Hemisphere Tethyan realm may indicate that
the genus is longitudinally as well as latitudinally en-
demic.

Xenosteges minusculus new species
Plate 4, figures 3-18

Etymology of Name.—L. minusculus = diminu-
tive.

Description.—Small to minute, very small for ge-
nus, unequally biconvex to concavo-convex, having
wide straight hinge. Operculiform dorsal valve deeply
inset into marginally flanged cup-like ventral valve.
Outline subcircular to semicircular. Umbonally ce-
mented to substrate; circlet of rhizoid attachment
spines along ventral hinge and umbo. Few propping
spines higher up anterolateral slopes of ventral valve.
Surface smooth or concentrically wrinkled. Attach-
ment plane at variable angles to plane of commissure,

commonly approaching or exceeding 90° in mature
specimens.

Ventral valve deep, cuplike, with wide flange sur-
rounding smaller dorsal valve. Flange commonly
everted to approximate plane of commissure. Umbo
commonly flattened, thinned or missing. Interarea
very low, having tiny open delthyrium. Ears variably
expressed, tapering gradually anteriorly into flanges.
Commonly widest at midvalve, slightly less wide at
hinge; deepest at midvalve. Flanks gradually sloping
anteriorly and laterally, cut off abruptly posteriorly at
attachment scar.

Dorsal valve commonly subcircular to semicircular
in outline. Immature valves convex; mature valves
commonly concavo-convex, having convex umbonal
region, raised margin and intervening concentric fur-
row. Surface concentrically wrinkled and dimpled; no
spines. Posteromesial projection of lophidium closing
delthyrium of ventral valve. Ears small, very thin, tri-
angular.

Ventral interior having triangular median umbonal
rise, providing attachment for paired adductor mus-
cles. Thickened marginal ridge extending from either
side of delthyrium toward flanges, longitudinally
grooved; groove articulating with corresponding ridge

BULLETIN 313

in dorsal valve. Hinge spines hollow, bases open,
communicating to exterior.

Dorsal interior having prominent marginal ridges
arising at base of cardinal process, slightly thickened
posteriorly to form ridges that articulate with grooves
in marginal ridges of ventral valve. Ridges continuing
around entire valve in some specimens, anteriorly
commonly expressed as abrupt dorsad deflection of
valve surface. Cardinal process on stout, short shaft,
bilobate or secondarily quadrilobate; myophore lobes
closely appressed or splayed. Submyophoral alveolus
present, produced anteriorly as shallow furrow; fur-
row healed anteriorly to produce narrow, anteriorly
raised median septum. Septum terminating posterior
to midvalve, often as pointed projection above valve
floor. Septum flanked posteriorly by paired inset pos-
terior adductor scars; surfaces of scars commonly tilt-
ed posteriorly from plane of valve floor. Brachial
ridges of productoid type, given off horizontally, com-
monly elevated and strong, terminating in circular
mounds at or posterior to midvalve. Interior surface —
otherwise smooth, except anteriorly endospinose in
some specimens. Endospines small, apparently in a
few concentric rows near margins.

Measurements (in mm).— |

VENTRAL VALVE

DorsAL VALVE

Ventral

Hinge Maximum Hinge Maximum Thick- Valve

Length Width Width Length Width Width ness Height
USNM 221057 2.3 De, 2.5 1.9 1.8 2.0 0.8 1.2

USNM 221058 Ths 2.5 3.0 2.7» 2.0 DES 1.0 1.7
USNM 221059 2.8 2.8 3.4 25 2. 2.8 1.0 1.2
USNM 221060 3°56 3.2 4.1 2.5 2.5 2.8 1.7 3.0
USNM 221061 BF2 4.0, 4.0 2.7 3.6), 3.1 1.2 2.0
USNM 221062 3.5 4.4 5.1 2.9 322 3.5) 2.3 3.7
(holotype)

Occurrence.—Xenosteges minusculus has been re-
covered only from locality 6. It is common in block A,
rare in block B and abundant in block C.

Diagnosis.—Very small Xenosteges having reduced
ears, strong dorsal interior marginal ridges and round-
ed, posteriorly set brachial ridges.

Types.—Holotype: USNM 221062; Figured Speci-
mens: USNM 221057-221059, USNM 221062—221071;
Measured Specimens: USNM 221057—221062.

Comparison.—Xenosteges minusculus is easily dis-
tinguished from all other known species of the genus
by its smaller overall size, the largest specimen being
slightly over five mm in its largest dimension. In ad-
dition, it is distinguished from X. adherens Muir-
Wood and Cooper (1960), X. anomalus Cooper and
Grant (1975) and X. trivialis Cooper and Grant (1975)

by its relatively narrow hingeline, compared to those
prominently auriculate forms. It lacks the ventral sul-
cus of X. magnus Cooper and Grant (1975), and is
more equidimensional than the commonly elongate X.
umbonatus Cooper and Grant (1975). Of the described
species of Xenosteges, X. minusculus probably most
closely resembles X. quadratus Cooper and Grant -
(1975), from which it differs in the smaller, more me-
sially appressed brachial ridges and the umbonally ©
concave dorsal valve of that form. |

Discussion.—Xenosteges minusculus is the first re- |
ported occurrence of the genus outside of the West i
Texas area, with the exception of two specimens from’
Thailand questionably assigned to the genus (Water-
house and Piyasin, 1970).

Material.— |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

Articu-
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation
6 (block A) 13 23 11 fine silicification
6 (block B) 3 2 1 fine silicification
6 (block C) 15 115 74 fine silicification

Family COOPERINIDAE Pajaud, 1968
Subfamily COOPERININAE Pajaud, 1968

Genus COOPERINA
Termier, Termier and Pajaud, 1966

Type Species.—Cooperina inexpectata Termier,
Termier and Pajaud, 1966, pp. 332-335.

Diagnosis.—Cooperininae bearing spines on both
valves, flangelike dorsal submarginal ridge, short but
prominent dorsal anteromedian ridge and elevated,
excavate adductor platforms.

Occurrence.—Cooperina is known in rocks of Penn-
sylvanian and Permian age, from every continent but
Africa, Australia and Antarctica. Its occurrence ap-
pears to be limited to the Tethyan realm during the
Permian. It first appears, reported as Leptalosia spon-
dyliformis White and St. John (1867) [in Dunbar and
Condra (1932)], in the Pawnee Formation (Laberdie
Limestone Member) of Late Desmoinesian age, from
Oklahoma. It is next seen in Thailand, in the Early
Permian of Ko Muk, as C. polytreta Grant (1976). C.
triangulata Cooper and Grant (1975), from the Lower
Wolfcampian of the West Texas area is another Early
Permian form. C. parva Cooper and Grant (1975) is
found at various localities in the Leonardian of West
Texas, while C. subcuneata Cooper and Grant (1975),
is at present limited to the Upper Leonardian of that
area. C. inexpectata has been recovered from various
localities from the Guadalupian of West Texas, and
| from locality 6, blocks A, B and C in this study of the
| Palmarito Formation. A form recognized as belonging
to the genus has been recovered from the Upper Perm-
| ian Zechstein of Germany (Grant, 1976, p. 89).
_ Comparison.—Cooperina is with great difficulty
distinguished from Ansehia Termier and Termier
(1970), and indeed the two genera are probably closely
related. Only the apparent absence of dorsal spines
and the latest Permian (Dzhulfian) age of the Cambo-
dian genus support the idea that they are distinct taxa.
A definitive decision must await development of the
internal details of Ansehia. Atelestegastus Cooper and
Grant (1975), lacks any ornament spines or an antero-
median ridge in the ventral valve interior, and pos-
sesses a characteristic wide flange around the cup-like
ventral valve, surrounding the inset dorsal valve. Fa-

nn
—

lafer Grant (1972), is easily distinguished by its prom-
inent muscle platform and its calcified ptycholophous
brachidium in the dorsal valve.

Discussion.—Cooperina was originally suggested
(Pajaud, 1968) as the ancestor to extant thecidian bra-
chiopods (e.g., Thecidellina). Subsequent studies
(Cooper and Grant, 1969; Grant, 1972; Cooper and
Grant, 1975; Grant, 1976) have demonstrated its prop-
er placement within the Productidina.

Cooperina inexpectata
Termier, Termier and Pajaud
Plate 4, figures 19-37

Cooperina inexpectata Termier, Termier and Pajaud, 1966, p. 332,
fig. 1; Cooper and Grant, 1969, pl. 3, figs. 14-27; Cooper and
Grant, 1975, p. 824, pl. 210, figs. 1-61; pl. 212, figs. 11-22.

Description.—Small to minute Cooperina having
straight hingeline, deeply concave ventral valve and
convex to concavo-convex dorsal valve. Rhizoid at-
tachment spines in circlet around ventral umbo and on
ears of ventral valve; crudely parallel rows of exterior
ornament spines; common on ventral valve, rare on
dorsal valve. Plane of commissure horizontal to ver-
tical, with respect to substrate, becoming more verti-
cal with growth.

Ventral valve outline ovate to subquadrate in dorsal
aspect. Umbonal region commonly modified or miss-
ing, depending on form of substrate. Attachment
spines densely packed, conforming to substrate; or-
nament spines straight or slightly curved, commonly
at low angle to surface, inclined toward plane of com-
missure. Interarea moderately high, commonly 0.15 of
shell length (Range: 0.11 to 0.21 in 12 specimens),
commonly orthocline to apsacline, very thin, over-
hanging posterior margin of dorsal valve to form
grooved hinge insertion. Broad ears gradually tapering
anteriorly, in dorsal aspect producing egg-shaped out-
line of visceral cavity. Thickened lateral and anterior
margins forming rim around inset dorsal valve margin.
Anterior margin, rounded, straight or very slightly in-
dented mesially.

Dorsal valve subquadrate, elongate rectangular or
rounded in outline, with or without slight anteromesial
indentation. Surface smooth to wrinkled, convex pos-
teriorly, concave anteriorly in more mature individu-
als. Ears tiny, thin, delicate, acuminate triangular.

Ventral interior deeply concave, of variable form
depending on attachment surface; umbonal region
commonly flattened or missing. Muscle scars indis-
tinct, on either side of low umbonal mound or broad
ridge. Umbonal mound merging anteriorly and dor-
sally into low, variably expressed median ridge. Ridge
broadening anteriorly, continuing to anterior margin,

58 BULLETIN 313

effectively dividing valve into two lobes, and articu-
lating with anteriorly divided anteromedian ridge of
dorsal valve.

Dorsal interior having thin, flangelike submarginal
ridges, arising laterally at base of cardinal process,
running just inside valve margins to reach highest
point at about midvalve, there turning anteromesially
and becoming lower toward the anterior margin, there
continued as a single row of small, low pustules.
Ridges re-arising mesially, recurving posteriorly to
conjoin near midvalve as high, anterodorsally grooved
median ridge. Median ridge gradually sloping ante-
riorly, sharply cut off posteriorly, merging into distinct
narrow median furrow nearer hingeline. Submarginal
ridges commonly (49 of 59 specimens) highest poste-

rior to highest point of anteromedian ridge; submar-
ginal ridges commonly (in 52 of 59 specimens) lower
than anteromedian ridge; neither relationship corre-
lated to growth stage. Delicate bilobate cardinal pro-
cess myophore set on short slender shaft, shaft at an-
gle to valve plane, allowing insertion below ventral
interarea. Myophoral lobes moderately splayed, dor-
soposteriorly cleft, producing effective quadriloba-
tion. Thin, obliquely-oriented adductor platforms set
in posterolateral corners of valve, attached laterally to
inside walls of submarginal ridges and posteriorly to
valve floor, merging posteriomesially into broad,
ridge-like bases of cardinal process shaft. Brachial
ridges poorly defined, elongate.
Measurements (in mm).—

VENTRAL VALVE

DorsAL VALVE

Inter-
Total Maximum area Hinge Maximum Thick-
Length Width Height Length Width Width ness
LOCALITY 6
(block C)
USNM 221072 1.8 1.8 0.2 1.4 0.6 1.5 0.4
USNM 221073 23 1.9 0.3 2.0 1.0 1e7/ 0.8
USNM 221074 2.6 2 0.3 De, les Dp) 0.3
USNM 221075 2) 2.8 0.4 2.6 1.2 23 1.2
USNM 221076 a2 2.8 0.5 2.3 1.4 D2 1.1
USNM 221077 33-3) 3.4 0.5 2.5 1.7 2.6 1.1
USNM 221078 3.4 2.4 0.5 DES ia 2.3 11-33
USNM 221079 3.4 3.1 0.7 2.4 1.6 2.3 1.6
USNM 221080 3.4 3.5 0.6 2.6 1.7 B03 2.0
USNM 221081 3t5 3.0 0.5 2.5 1.8 22. 1.6
USNM 221082 3.6 2.9 0.6 2S 123 2.2 2.0
USNM 221083 3.6 3.0 0.6 2.6 1.4 2.3 1.6

Occurrence.—Cooperina inexpectata is known
from rocks of Guadalupian age in the West Texas area.
The specimens herein described constitute the other
known occurrence of the species. Individuals have
been recovered only from locality 6, blocks A, B, and
C. They are common to abundant in blocks A and C,
but are rare in block B.

Diagnosis.—

Rectangular to square Cooperina having long curved ornament
spines, a broad attachment area on the pedicle valve and strongly
elevated median ridge in the brachial valve. (Cooper and Grant,
1975, p. 825)

Types.—Figured Specimens: USNM 221075, USNM
221079, USNM 221084, USNM 221086, USNM
221092, USNM 221104, USNM 221112, USNM
221117, USNM 221118, USNM 221121, USNM
221132, USNM 221142-221146. Measured Specimens:
USNM 221072-221142.

Comparison.—Cooperina inexpectata is easily dis-
tinguished from the only other Palmarito brachiopod

of similar form and size, Xenosteges minusculus n.—
sp., by its more elongate form and its strikingly dif-
ferent interior details. It may be distinguished from
other species of Cooperina with somewhat more dif- —
ficulty. It is distinguished from C. swbcuneata Cooper
and Grant (1975) by the narrow hinge and conspicuous ~
brachial pits in that form. It is generally larger and less
triangular than C. triangulata Cooper and Grant (1975) |
and has ornamental spines, which that form lacks. It”
is similarly distinguished from C. spondyliformis —
(White and St. John, 1867). C. parva Cooper and —
Grant (1975) bears close resemblance to juvenile and
apparently neotenous (large but with low dorsal me- |
dian and submarginal ridges) individuals of Cooperina ©
inexpectata from the Palmarito Formation, but is not
placed in synonymy here because the two species do!
not overlap in many taxonomic characters in the West!
Texas area where they were defined. i

Discussion.—The dorsal valve of Cooperina, prob- |
ably less affected by local environmental variables i

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 59

(substrate type, site of attachment, etc.) than the ven-
tral may be defined in outline by three measurable
variables: hinge, or minimum width, maximum width,
and length. Some concept of the shape variability of
the species can be gained through a plot, on a trian-
gular diagram of these variables, normalized to 100%
(Text-fig. 9). This diagram shows four variability
fields. The point within each defines the position of
the mean of the indicated variable: the polygon sur-
rounding that point extends one standard deviation to
each side of the mean, and the dotted line surrounding
the polygon is a measure of the range of variation of
the form described. The data on which the illustration
is based are presented as Table 9. The numerical trans-
formations employed are summarized in Table 10.

In terms of outline of the dorsal valve, the four
forms are clearly related. There is considerable over-
lap between the Venezuelan forms (C & D), which are
here considered as different ontogenetic stages of the
same species. There is no overlap between the ranges
of variation in shape of the two West Texas forms (A
& B), but it is readily apparent that they are related
in much the same manner as are the Venezuelan
forms, though not so closely.

LENGTH (%)

= ne
| MIN. WIDTH (%) 31 27 23 19 15

Text-figure 9.—Shape variation of dorsal valves of four samples
of Cooperina from the Permian of West Texas and Venezuela. Field

surrounded by ------ = Cooperina inexpectata from West Texas;
field surrounded by ------ = Cooperina parva from West Texas; field
surrounded by —:—-—:— = mature Cooperina inexpectata from
Venezuela; field surrounded by —— = apparent immature Coop-

erina inexpectata from Venezuela. (Within each field, the coded line
surrounds all data points; the polygon defines one standard devia-
tion on each side of the mean for all three variables; the point within
each polygon is the mean for all three variables. Data are summa-
|rized in Tables 9 and 10.)

One possible resolution of this situation might be to
designate three species: C. inexpectata, as typified by
the West Texas forms (field A), C. parva, again typ-
ified by West Texas specimens (field B), and a new
Venezuelan species of Cooperina. This strategy is not
employed because there is no obvious morphological
difference between C. inexpectata of West Texas and
the mature Venezuelan forms that cannot be explained
in terms of normal infraspecific variation. Since forms
transitional between juvenile and mature individuals
are observed in the Venezuelan collections, it is rea-
sonable to combine them as a single species. It cannot
be determined whether the juvenile ontogenetic stage
seen in Venezuela is genetically related to the appar-
ently neotenous species of C. parva of West Texas.
It is, however, reasonable to consider similar mor-
phologies in fossils as representing ontogenetically
distinct but genetically conspecific organisms in one
place and time, while they represent genetically dis-
tinct species in another. Geographic and temporal sep-
aration are recognized factors in speciation.

Family RHAMNARIIDAE Muir-Wood and
Cooper, 1960

RHAMNARIIDAE cf. Ramavectus sp.
Plate 4, figures 38, 39

cf. Ramavectus Stehli, 1954, p. 327 ff.

Types.—Figured Specimen: USNM 221147.

Discussion.—A single poorly preserved specimen
recovered from locality 11 is questionably referred to
Ramavectus. It is largely decorticated, the only re-
maining shell material being several pieces of ventral
valve surface, the ventral beak and the proximal por-
tion of the dorsal umbo. The umbonal region has been
silicified as a unit, so that the form of the cardinal
process is lost. Grinding the umbonal region did not
reveal the presence of the large median septum char-
acterisitc of Tschernyschewia Stoyanov (1910). The
absence of a distinct cicatrix of attachment suggests
that it does not belong in either Rhamnaria Muir-
Wood and Cooper (1960), Spuriosa Cooper and Grant
(1975) or Juresania Frederiks (1928), externally simi-
lar forms. In addition, most species of Rhamnaria are
smaller, and none bears the distinctive regularly
spaced elongate spine bases on the ventral valve that
in Ramavectus, and the Palmarito specimen, suggest
periodically interrupted costae. The specimen might
be mistaken on casual inspection for a large species
of Bathymyonia Muir-Wood and Cooper (1960), but
the presence of a true interarea in the Palmarito form
clearly removes it from the Echinoconchidae.

60 BULLETIN 313

Table 9.—Measurements of dorsal valves of Cooperina inexpectata Termier, Termier and Pajaud (1966) from locality 6, Palmarito For-
mation.

SMRH = Submarginal Ridge Height

MRH = Median Ridge Height

SMRD = Distance from highest point on submarginal ridge to anteriormost point of shell, measured parallel to shell length.

MRD = Distance from highest point on median ridge to anteriormost point on shell, measured parallel to shell length.

Hinge Minimum Maximum
Length Width Width Width SMRH MRH SMRD MRD
(block A)
USNM 221084 2.4 1.0 1.0 2.6 0.6 1.0 1.3 1.1
USNM 221085 2a 1.0 1.0 2.2 0.6 0.5 1.1 0.7
USNM 221086 2.1 1.4 1.3 2.0 0.7 1.1 1.6 1.1
USNM 221087 2.1 1.4, 1.3, 2.1 0.6 0.7 ED 1.0
USNM 221088 Dal 1.5 3 2.0 0.7 1.0 1.4 1.0
USNM 221089 D2 0.9 0.9 1.9 0.4 0.7 12 0.7
USNM 221090 2.2 1.4 1.2 2.0 0.6 0.8 0.9 0.7
USNM 221091 2.2 1.4, 1.1, Dl 0.6 0.7 1.4 0.9
USNM 221092 2D. 1.3 1.2 2.2 0.7 0.9 122 0.8
USNM 221093 2.2 1.4 13} 2.4 0.9 0.9 1.2 1.0
USNM 221094 23 isa 1.6 2.3 0.6 1.0 1.3 1.0
USNM 221095 23 1.2 152 2.4 0.6 0.9 0.8 1.0
USNM 221096 2.3 1.3, 113} 2.4 0.8 1.3 1.6 1.1
USNM 221097 233) 2.1h 1.9, 2.6 0.7 0.7 1.4 1.1
USNM 221098 2.4 1.6 1.5 2.2 0.7 1.0 1-5) 1.0
USNM 221099 2.4 2.0 1.6 Deg) 0.7 0.9 1.1 EV }
USNM 221100 2.4 0.9 0.9 2.3 0.6 0.9 [3 1.3
USNM 221101 2.4 1.3 1.1 23 0.6 0.9 1.6 ilcil
USNM 221102 2.4 1.3 i1.3) 2.3 0.6 iol 1.3 1.0
USNM 221103 2.4 1.3 1.3 2.4 0.7 1.1 1.2 0.9
USNM 221104 2.4 1.3 1.3 2.4 0.8 ito 1.6 1.4
USNM 221105 2.4 1165) 1.4 DES 0.7 1.0 1.3 1.2 |
USNM 221106 2.4 1.6 (les) 2S 0.9 1.1 iL) 1.4 }
USNM 221107 2.4 1.0 1.0 2.6 0.6 1.0 1.3 1e1 |
USNM 221108 2S 1.8 1.4 2.0 0.6 0.9 1.8 0.9 |
USNM 221109 DES 1.4, es) 29) 0.7 1.1 1.9 13
USNM 221110 2S 1.0 1.0 2.4 1.0 1.2 i133 151
USNM 221111 2.5 1.5 1.4 2.4 0.8 1.2 1.2 12
USNM 221112 DES 1.4 13) 2.5 0.9 1.5 eS 12 i
USNM 221113 3) 1.8 1.4 DES 0.6 1.0 1.6 ila
USNM 221114 2.5 1.9 1.8 2.6 0.7 1.0 iL) 1:2
USNM 221115 2.6 eS) ity 2.3 0.6 0.7 1.6 1S
USNM 221116 2.6 1.8, 1.8), Del 0.8 1.0 FD IBS)
(block C)
USNM 221117 1.4 1.0 0.9 1.7 — 0.1 _ 0.5
USNM 221118 1.6 1.3 1.3 1.9 0.4 0.3 0.9 0.3
USNM 221119 1.8 1.4 1.3 DD 0.2 0.1 _ 0.6
USNM 221120 1.9 1.3 1.1 2.0 0.3 0.7 1.1 0.7
USNM 221121 1.9 1.5 1.5 2.1 0.4 0.6 1.3 0.6
USNM 221122 2.0 1.4, 1.2, 2.3 1.1 0.9 1.4 0.8
USNM 221123 Dy 1.4), 1.4, 1.9 0.8 0.9 1.2 0.8
USNM 221124 ep) 1.5 1.3 1.9 0.6 0.7 1.0 0.6
USNM 221125 2.2 1.1 1.1 YG) 0.3 0.6 1.5 0.8
USNM 221126 2.2 1.5 1.4 252 0.6 0.7 118) ile
USNM 221127 2.2 1.05» 1.0pn 2.4 12 1.2 1.1 0.9
USNM 221128 ED 1.8, led 2.4 0.6 0.6 1.3 1.1
USNM 221129 2.3 1.8, 1.4, 2.3 0.6 0.9 1.4 0.9
USNM 221130 253 i163} 1.3 3} 0.7 0.9 Nez 0.8
USNM 221131 2.3 s1-5) 1-5) 2.4 0.7 1.1 1.3 1.0
USNM 221132 DES, 1.9 1.8 2.6 0.4 0.7 1.4 0.8
USNM 221133 2.4 1.0 1.0 223 0.8 1.2 ile? 1.0
USNM 221134 2.4 1.6 1.6 2.4 0.8 1R2 1.6 1.1
USNM 221135 2.4 1.4 1.4 2.6 1.0 1.1 (lez) 1.0

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

Table 9.—Continued.

SMRH = Submarginal Ridge Height
MRH = Median Ridge Height

SMRD = Distance from highest point on submarginal ridge to anteriormost point of shell, measured parallel to shell length.
MRD = Distance from highest point on median ridge to anteriormost point on shell, measured parallel to shell length.

Hinge Minimum Maximum

Length Width Width Width SMRH MRH SMRD MRD
USNM 221136 2.4 i E7/ 2.6 1.0 1.4 71 2
USNM 221137 2.5 1.8, 1.7, 2.5 0.6 0.9 1.4 1.1
USNM 221138 755) 1.8), 1.4, 2.6 0.6 0.9 iss) 1.0
USNM 221139 2.5 1.6 1.6 2.6 0.6 1.2 1.3 i 72
USNM 221140 2.6 hail 1.1 2.9 0.9 1,72 1.0 1.2
USNM 221141 Dell aa 1.9 2.6 0.9 1.1 1.5 ile
USNM 221142 2.8 Dal 1.9 2a3) 0.6 1.0 1.7 1.0

Table 10.—Statistics calculated from measurements of dorsal valves of two species

of Cooperina Termier, Termier and Pajaud (1966).

Cooperina inexpectata
Mature individuals from West Texas
9 specimens
[USNM 152637a-i]

Cooperina parva
Mature individuals from West Texas
6 specimens
[USNM 152638a—c; USNM 152639d, e, g]

| Cooperina inexpectata
Mature individuals from Venezuela
53 specimens

USNM 221133-221142]

Cooperina inexpectata
Apparent juvenile individuals from Venezuela
6 specimens
[USNM 221117-221121, USNM 221132]

[USNM 221084-221116; USNM 221122-221131;

Measured Calculated Value

Parameter Statistic (in mm)
Hinge Width mean 2.30
standard deviation 0.59

range 1.3-3.0
Maximum Width mean 3.14
standard deviation 0.65

range 2.0-4.2
Length mean 3.46
standard deviation 0.71

range 2.3-4.5
Hinge Width mean 1.28
standard deviation 0.29

range 1.0-1.8
Maximum Width mean 1.95
standard deviation 0.35

range 1.5-2.4
Length mean 1.40
standard deviation 0.11

range 1.2-1.5
Hinge Width mean 1.35
standard deviation 0.27

range 0.8—2.1
Maximum Width mean 2.34
standard deviation 0.21

range 1.9-2.9
Length mean 2.35
standard deviation 0.17

range 2.0-2.8
Hinge Width mean 1.32
standard deviation 0.31

range 0.9-1.8
Maximum Width mean 2.08
standard deviation 0.31

range 1.9-2.6
Length mean 1.82
standard deviation 0.31

range 1.4-2.3

62 BULLETIN 313

The roughly triangular outline, small ears, bunch of
fine spines along the hinge, short hingeline, distinct
interarea and peculiar spine arrangement clearly sug-
gest placement of this form within the Rhamnariidae,
but do not permit more than tentative assignment to
the genus Ramavectus.

Superfamily PRODUCTACEA Gray, 1840
Family MARGINIFERIDAE Stehli, 1954
Subfamily COSTISPINIFERINAE
Muir-Wood and Cooper, 1960

Genus ECHINAURIS Muir-Wood and Cooper, 1960

Type Species.—Echinauris lateralis Muir-Wood and

Diagnosis.—

Costispiniferinae ornamented by spines and spine ridges on ped-
icle valve and spines and dimples on brachial valve, lateral halteroid
spines long and extended laterally. (Cooper and Grant, 1975, p.
1000)

Occurrence.—The various species assigned to the
genus Echinauris have been recovered from rocks
ranging in age from earliest Wolfcampian to Early
Guadalupian equivalents. It has been reported from
West Texas (Muir-Wood and Cooper, 1960; Cooper
and Grant, 1975), Guatemala (Stehli and Grant, 1970),
Greece (Grant, pers. comm., 1974), Tunisia (Termier
and Termier, 1957), Pakistan (Grant, 1968), Nepal?
(Waterhouse, 1966), China (Chao, 1927), Thailand
(Waterhouse and Piyasin, 1970; Grant, 1976) and Ti-
mor (Broili, 1916).

Comparison.—Echinauris is distinguished from El-
liottella Stehli (1955) and Oncosarina Cooper and
Grant (1969) by the lack of dorsal exterior spines in
the latter forms; from the Asian genus Haydenella
Reed (1944) by the paucispinose ventral valve of that
form; from Costispinifera by the greater spine density
and anterior ventral costation of that form; from Both-
rionia Cooper and Grant (1975) by the fold-sulcus de-
velopment and ventral marginal rim of that form. The
most readily apparent diagnostic characters of Echi-
nauris are the aspinose “‘denuded”’ ventral umbonal
region, the centripetally-directed dorsal spines, and
the absence of strong radial ornament on either valve.

Discussion.—Echinauris has not been reported from
Australia, southern Africa, or either polar region. In
the Permian, it appears to have had a Tethyan (‘“‘trop-
ical’’ to ‘‘subtropical’’) distribution.

Echinauris bella Cooper and Grant
Plate 4, figures 40-55; Plate 5, figures 1—2

Echinauris bella Cooper and Grant, 1975, p. 1003, pl. 326, figs. I-
58; pl. 410, figs. 9-13.

Description.—Small, less than average-sized for ge-
nus, concavo-convex shells; ovate outline interrupted
by ventral ears. Commonly widest at hinge, but ears
delicate, commonly broken or missing. Umbo swollen,
greatest height at hinge. Both valves spinose; spines
long, slender, curving. Anterior margin commonly
evenly rounded, rarely slightly sulcate, straight in an-
terior view. Surface smooth, having faint concentric
wrinkles or faint low costae, produced anterior to
spine bases and quickly becoming obsolete anteriorly.

Ventral valve convex, having small apical cicatrix
of attachment; umbo commonly overhanging long
straight hingeline. Umbonal slopes of mature speci-
mens bearing spine bases but no spines; delicate um-
bonal spines present in attached (cemented) juveniles.
Interarea missing, but weak, very low ginglymus spo-
radically developed. Single row of posteroventrally
directed small spines along hinge; one to several ir-
regular rows of spines ventral to hinge. Cluster of long,
halteroid spines arising at break in slope of flanks, just
ventral to, but not on ears; directed laterally, ventro-
laterally, and posteroventrolaterally. Ears narrow, tri-
angular, set at a sharp angle to body, not bearing >
spines. Ornament spines sheathing remainder of valve, —
arising in roughly concentric rows normal to shell sur-—
face, turning abruptly anterodorsally following shell”
surface; last few generations curving dorsoposteriorly |
Over anterior margin. Weak low costae, arising at
spine bases, becoming obsolete anteriorly.

Dorsal valve concave, semi-circular in outline, hav-
ing sloping flanks; commonly auriculate, ears thin, del-
icate, rarely preserved; reflexed, lying in plane of com-_
missure. Spinelike lophidium, anterodorsally directed, —
projecting slightly beyond hinge. Surface pitted or
very rarely bearing numerous short, very fine erect.
spines, anteriormost spines centripetally directed.
Paired tufts of more commonly preserved, long cen-
tripetally-directed straight or slightly curving spines
arising on ears and arching over vault of valve.

Ventral interior having deep umbonal cavity with
low apical longitudinal ridge; ridge in articulated
valves lying between lateral lobes of cardinal process.
Elongate, anteriorly broadened adductor scars faintly
impressed in median valve floor, flanked posteriorly
by small, more equidimensional diductor scars. Ears
slightly concave, abruptly separated from body cavity
by coarsely crenulate ridges.

Dorsal interior having characteristic W-shaped car-
dinal process myophore, each lobe U-shaped poste-
riorly. Lobes appressed dorsally, moderately splayed
ventrally; posteroventral extremities somewhat angu-!
lar. Myophore set on short stout shaft; shaft bearing
median ventral furrow. Weakly crenulate low marginal

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 63

ridges arising at base of shaft, running laterally, rarely
continuing to anterior margin. Thin, low breviseptum
running anteriorly from furrow of cardinal process
shaft, terminating about midvalve. Anterior extremity
pointed, free of valve floor in mature specimens, in
gerontic specimens having expanded, spatulate, ven-
trally directed tip. Anteriorly broad, triangular, ap-
parently smooth anterior adductor muscle scars flank-
ing median breviseptum, somewhat raised on
platforms. Posterior adductor scars smooth, small,
elongate oval, somewhat inset into valve floor. Bra-
chial ridges given off horizontally, commonly faintly
raised, rarely endospinose anteriorly, endospines low.
Valve surface very finely pustulose, pustules in radial
rows nearer anterior and lateral margins.
Measurements (in mm).—

Dorsal
Valve Hinge Mid-
Length Length Width Width Height
Locatity 13
USNM 221148 4.5 3.8, 4.0, 4.6 2.0
USNM 221149 Se 4.7 5.0, 6.5, 23
USNM 221150 5.8 5.3 5.0, 6.1 2.7
USNM 221151 6.8 5.8 7.0, 8.0 3.6
USNM 221152 8.0 6.5 7.5» 8.7 39)
USNM 221153 8.2 TAO) 7.4, 9.2, 5.0
USNM 221154 8.5 7.0 8.6, 8.9 5.9
USNM 221155 8.6 6.1 6.7, 8.6 5.0
USNM 221156 8.7 6.5 OIE 9.0 525
USNM 221157 8.9 7.0 9.4, 8.7 5.6
USNM 221158 9.0 We2e 8.2, 9.2 5.6
USNM 221159 9.0 7.0 7.0, 9.6 5.6
USNM 221160 9.1 6.9 8.2, 9.1 4.8
USNM 221161 92 6.6 8.9, 8.6 6.7
USNM 221162 9.3 7.0 10.2, 10.0 5.6
USNM 221163 9.6 7.0 8.5, 8.2, 6.0
USNM 221164 9.6 6.7 9.3, 9.0 So)
USNM 221165 9.6 US) 10.0, OFF, Sel
USNM 221166 10.0 6.5 9.8, 9.2, 6.2
USNM 221167 10.0 Bell 10.0, 10.5 6.0
USNM 221168 10.2 6.9 8.6, 7.9 6.3
USNM 221169 10.3 8.0, 10.6, 9.4 6.9
USNM 221170 11.0 etl 9.0, 9.0 fei
USNM 221171 ESS US¥: 10.9, 11.7 7.0
USNM 221172 12.7 8.4 11.7, 11.1, 6.6

Occurrence.—Echinauris bella is found in the West
Texas area in the Cibolo and Road Canyon Formations
of Late Leonardian age. In the Palmarito Formation
it has been recovered from locality 13, where it is by
far the most abundant brachiopod. A single well-pre-
served dorsal valve of E. bella was recovered from
locality 6, block C.

Diagnosis.—Small Echinauris, with length and
width nearly equal, but hinge commonly greater than
midwidth, and scattered spines.

Types.—Figured Specimens: USNM 221173221183;
Measured Specimens: USNM 221148-221172.

Comparison.—The diminutive size of E. bella ef-
fectively separates it from E. boulei (Kozlowski,
1914), E. interrupta Cooper and Grant (1975), E. ir-
regularis Cooper and Grant (1975), E. lappacea Coo-
per and Grant (1975), E. lateralis Muir-Wood and
Cooper (1960), E. liumbona Cooper and Grant (1975),
E. magna Cooper and Grant (1975), E. productel-
loides Cooper and Grant (1975), E. subhorrida (Meek,
1877) and E. subquadrata Cooper and Grant (1975) of
the West Texas area. The heavy and sparsely distrib-
uted spines of E. crassa clearly differentiate that form
from E. bella. The spinose brachial ridges best devel-
oped in E. venustula Cooper and Grant (1975) are
missing from E. bella, thus distinguishing that form.
The Guatemalan species E. huehuetenanguensis Steh-
li and Grant (1970) is somewhat larger, and more trans-
verse than E. bella. The Asian species E. opuntia
(Waagen, 1884) and the Chinese species E. jisuensis
(Chao, 1927) are both larger forms than E. bella. The
three species E. circularis Cooper and Grant (1975),
E. parva Cooper and Grant (1975) and E. venustula
exhibit several characters in common: narrow ventral
hinge, as compared to the midwidth; variable density
and directional development of long thin endospines
along the anterior portions of the brachial ridges. Al-
though the latter character was mentioned in a dis-
cussion of E. bella (Cooper and Grant, 1975, pp. 1003,
1005), I was unable to discover it in specimens referred
to the species in the National collections.

Discussion.—The Palmarito forms are assigned to
the species E. bella, although there are important dif-
ferences between them and populations of the species
in the West Texas area where it was first described.
Text-figure 10 shows variability in form of the ventral
valve in samples of E. bella from West Texas and
Venezuela, as described by their length, midwidth and
height. Although there is considerable overlap of the
variability fields of the two samples, the North Amer-
ican form has greater length and midwidth compo-
nents, while the Venezuelan specimens are propor-
tionally higher. This is in part due to the higher
proportion of juvenile specimens in the West Texas
sample, but even with this bias recognized, the West
Texas forms are a bit more transverse than their Ven-
ezuelan counterparts. In addition the West Texas
forms have finer, more slender spines on both valves
and tend to be shallower than the Venezuelan speci-
mens. Spine diameter may be a parameter which is
covariant with the substrate encountered by the set-
tling spat (Grant, pers. comm., 1974). Judging from
the development of the median breviseptum of the

64 BULLETIN 313

dorsal valve and the muscle attachment impressions

in both valves, none of the E. bella from West Texas

appear to have reached the same ontogenetic age as

that seen in many gerontic Venezuelan specimens.
Material.—

Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
6 (block C) — 1 —_ fine silicification
13 83 50 294 fine silicification

Echinauris cf. E. lappacea Cooper and Grant
Plate 5, figures 3-12

ef. Echinauris lappacea Cooper and Grant, 1975, p. 1010, pl. 336,
figs. 1-31; pl. 476, figs. 1-18.

Description.—Small to medium-sized, average-sized
for genus, concavo-convex shells; outline transversely
oval to transversely rectangular; commonly widest at
hinge. Ears small, triangular, delicate, set off from
visceral cavity. Umbo low, only slightly swollen, not
incurved over hingeline, without apical cicatrix of at-
tachment. Both valves bearing spines of various sizes.
Anterior margin commonly rounded to slightly in-
dented in dorsal aspect; straight in anterior aspect.

Ventral valve deeply convex; greatest height com-
monly at midvalve. Umbonal slopes bearing spine bas-

HEIGHT (%)

eee eee es

- s
MID - WIDTH (%) 46 42 38 34

Text-figure 10.—Comparison of shell form of two population sam-
ples of Echinauris bella Cooper and Grant (1975). Dotted lines in-
dicate statistics derived from measurements of a West Texas sam-
ple; solid lines indicate statistics derived from measurements of a
Venezuelan sample; © indicates the mean of the distribution; the
polygon surrounds one standard deviation on each side of the mean
for all three variables; the ovoid form surrounds all pertinent data
points.

es but no spines. Low ginglymus present. Several ir-
regular rows of spines ventral to hinge and on ears.
Spines irregularly scattered over remainder of surface;
more densely packed on lateral than mesial slopes,
quincunxially arranged or in roughly concentric rows.
Spine bases anteriorly somewhat elongate, suggesting
costae. Slight mesial sulcus developed in larger spec-
imens.

Dorsal valve concave; greatest depth anteriorly.
Surface dimpled and spinose. Spines in dense wedge
radiating anterolaterally from umbo, corresponding in
position to break in slope between ears and visceral
cavity; also on ears. Less densely packed, more slen-
der, centripetally directed spines on remainder of
valve exterior. Slight anteromesial fold developed in
larger specimens.

Ventral interior unknown.

Dorsal interior having ‘‘ginglymus,’’ perhaps artic-
ulating with negative structure in ventral valve, and
pointed small lophidium. Cardinal process small, com-
pact, broad-based, W-shaped in posterior aspect, hav-
ing disjunct, vertically oriented bladelike lateral lobes
and higher, broader ventromesial lobe. Lateral ridges
diverging from hinge, continuing only to lateral mar-
gins. Alveolus not observed. Cardinal process merging
anteriorly into broadened breviseptum; breviseptum
separating two pairs of narrowly elongate muscle at-
tachment scars. Muscle scars anteriorly raised on plat-
forms; surfaces minutely crenulate, sloping postero-
laterally. Breviseptum continued anterior to muscle
scars as narrow, bladelike ridge, terminating in an-
teroventrally directed point just anterior to midvalve.
Remainder of interior surface otherwise minutely pus-
tulose.

Measurements (in mm).—

Dorsal
Valve Hinge Mid-
Length Length Width Width Height
Loca.ity 11

USNM 221184 9.6 8.0 10.2, 11.6 6.2
USNM 221185 10.5 8.8 13.5 11.2 7.8
USNM 221186 10.5 8.7 12.1, 11.5 7.9
USNM 221187 Sy 8.5 9.45. 11.8 TAA)
USNM 221188 12.0 10.3 16.5), 15.0 i?
USNM 221189 12.9pe 10.656 17.0pe 15.5 8.9
USNM 221190 13.5 11.1 16.35. 15.2 WED

Occurrence.—E. lappacea is known only from the
Road Canyon Formation of the West Texas area. In
the Palmarito fauna E. cf. E. lappacea has been re-
covered only from locality 11. A Late Leonardian age
for this unit is not inconsistent with other faunal evi-
dence.

|
|
|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 65

Diagnosis.—Subrectangular Echinauris with low
umbonal region, not overhanging hinge, coarse scat-
tered ornament spines and thick mat of spines on dor-
sal valve.

Types.—Figured Specimens: USNM 221185, USNM
221188, USNM 221191-221193; Measured Specimens:
USNM 221184—-221190.

Comparison.—Echinauris cf. E. lappacea is easily
distinguished from E. bella Cooper and Grant (1975),
E. circularis Cooper and Grant (1975), E. crassa Coo-
per and Grant (1975), E. huehuetenanguensis Stehli
and Grant (1970), E. parva Cooper and Grant (1975)
and E. venustula Cooper and Grant (1975) by its larger
size, and from E. magna Cooper and Grant (1975), E.
subhorrida (Meek, 1877), E. subquadrata Cooper and
Grant (1975) and E. sp. Stehli and Grant (1970) from
the Chochal Limestone of Guatemala, by its smaller
size. It is distinguished from E. lateralis Cooper and
Grant (1975) by its wider hinge, from E. boulei (Koz-
lowski, 1914) by the pronounced ventral costation of
that form, and from E. huehuetenanguensis, E. inter-
rupta Cooper and Grant (1975), E. liumbona Cooper
and Grant (1975) and E. productelloides Cooper and
Grant (1975) by the more swollen, incurved umbo of
those forms. Of the West Texas forms it most closely
resembles E. irregularis Cooper and Grant (1975),
from which it differs in its lower umbonal region and
more transverse outline. It differs from E. opuntia
(Waagen, 1884), from the Salt Range, in its lower
umbo and less pronounced ventral costae.

Discussion.—The Palmarito specimens cannot def-
initely be assigned to the species E. lappacea, because
they lack the dorsal endospines characteristic of the
species in the West Texas area from which it was first
described, because no ventral interiors are available
for comparison, and because the suite of specimens is

too small to give a fair representation of the range of

variation that may be present.

monly having greatest width anterior to hinge. Umbo
commonly swollen, produced considerably posterior
to hinge. Trail long; greatest height commonly anterior
to midvalve. Ears small, delicate. Both valves sparsely
spinose; dorsal spines very delicate, rarely preserved.
Distinct broad ventral sulcus; indistinct dorsal fold.
Commissure straight in anterior aspect.

Ventral valve deeply convex; tightly spiralled.
Umbo high, apex slightly overhanging hinge; umbonal
slopes steep; ears small, at sharp angle to body of
shell. Median sulcus arising anterior to umbo, con-
tinuing to anterior margin. Broad band of spines run-
ning up break in slope between ears and umbonal
slopes; scattered on flanks; in cluster just ventral to
ears, and continuing around anterior margin. Umbo
and posterior umbonal slopes non-spinose to sparsely
spinose; spines rare in sulcus except anteriorly, low
obsolete spine ridges there producing faint costation.

Dorsal valve broadly concave; greatest depth at
midvalve, commonly markedly transverse. Ears small,
delicate; set at sharp angle to body; rarely preserved.
Ornament of concentric rugae and dimples; delicate
spines present, but rarely preserved.

Ventral interior having two pairs of muscle scars in
umbonal apex; mesial pair narrow, elongate, appar-
ently smooth, set on slight callus platform. Smaller
elongate lateral pair of smooth scars set slightly pos-
teriorly, not on platforms. Ear baffles developed:
slightly raised, interiorly striate; striae directed pos-
teroventral-anterodorsal. Ears slightly concave. Re-
mainder of surface finely pustulose.

Dorsal interior having large trilobate cardinal pro-
cess myophore with short shaft. Two pairs of elongate
triangular adductor scars flanking posterior portion of
narrow breviseptum; breviseptum terminating near
midvalve. Rough row of large endospines across an-
terior portion of the valve anterior to breviseptum, but
indented posteriorly to meet end of breviseptum. Bra-

Material.— chial ridges indistinct.
; Measurements (in mm).—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation Dorsal :
Valve Mid-
11 19 1 — coarse silicification Length Length Width Height
LOcALITy 4
USNM 221211 11.6, 9.1. 14.1 7.4,
O a A 221212 14.5 2.0. Bre Se
Echinauris cf. E. liumbona Cooper and Grant ee 51013 19.9, - : st i 5 ae
Plate 5, figures 13-19 ) pa ma tt cw ay
LOCALITY 7
cf. Echinauris liumbona Cooper and Grant, 1975, p. 1012, pl. 337, USNM 221205 12.5 10.5 14.1 De
figs. 1-36. USNM 221206 13.9 TS 16.2 9.9
ca bate 2 : 3 USNM 221207 14.9 11.8 14.4 9.3}
Description.—Medium-sized, average-sized for ge- USNM 221208 15.0, 114, ise 10.9..
nus, slightly to markedly transverse, concavo-convex USNM 221209 16.Or. 11.0, 15.2 9.4.
shells; outline subpentagonal to sub-trigonal; com- USNM 221210 ith. 12.9, 17.8 11.4,

66 BULLETIN 313

Measurements (in mm).—Continued

Dorsal
Valve Mid-
Length Length Width Height
LOCALITY 8

USNM 221194 11.6 10.3 15.4 7.6
USNM 221195 12.5 10.8 16.8 8.0
USNM 221196 13.Spe 11.3 16.5 9.1
USNM 221197 13.8 10.9 22.2, 9.By6
USNM 221198 14.5. 12.4, 18.0, 9.0.
USNM 221199 14.9 11.4 1Se2) 9.3
USNM 221200 15.4 ES 18.4 9.8
USNM 221201 16. 1p. ES 18.2 10. 1p.
USNM 221202 16.4 Pn 21.0, 10.1).
USNM 221203 16.64. 13.5. 20.0 11.7,
USNM 221204 16.8 1235 17.1 10.9

Occurrence.—Echinauris liumbona occurs in the
West Texas area only in the Road Canyon Formation,
of Late Leonardian age. In the Palmarito fauna it has
been recovered at localities 1, 4, 7 and 8. It is uncom-
mon to rare at localities 1, 4 and 8 and common to
abundant at locality 7. A Late Leonardian age for the
Palmarito localities in which it occurs is consistent
with biostratigraphic evidence provided by other fau-
nal elements.

Diagnosis.—Subrectangular to transverse Echi-
nauris with nearly naked umbonal regions, few spine
ridges, emarginate anterior and swollen umbo.

Types.—Figured Specimens: USNM 221203, USNM
221204, USNM 221213; Measured Specimens: USNM
221194—221213.

Comparison.—E. liumbona may be distinguished
from E. bella Cooper and Grant (1975), E. circularis
Cooper and Grant (1975), E. crassa Cooper and Grant
(1975), E. irregularis Cooper and Grant (1975), E. par-
va Cooper and Grant (1975), and E. venustula Cooper
and Grant (1975) by the smaller average size of ap-
parent mature individuals of those forms, and from E.
boulei (Kozlowski, 1914), E. magna Cooper and Grant
(1975), E. subhorrida (Meek, 1877) and E. subquad-
rata Cooper and Grant (1975) by the larger average
size of apparent mature individuals of those forms.
The comparatively wide hinge of E. interrupta Cooper
and Grant (1975), E. lateralis Cooper and Grant (1975)
and E. productelloides Cooper and Grant (1975) ef-
fectively distinguishes E. liumbona from those forms.
E. cf. E. liumbona from the Palmarito Formation
lacks the clusters of spine bases on the dorsal ears that
are characteristic of E. lappacea Cooper and Grant
(1975). On the Venezuelan form, the band of spines
below the ventral ears that extends across the anterior
margin, is one of its characteristic features. E. cf. E.

liumbona is outwardly similar to forms described as —

Echinauris sp. (Stehli and Grant, 1970, p. 32, pl. 8,
figs.

form to allow a more definitive comparison. The spec-
imens here referred to E. liumbona also bear external
resemblance to an undescribed form (Wardlaw, pers.
comm., 1975) from the Gerster Formation (Wordian
of Nevada). That form, assignable to the Paucispini-
feridae, is generally more spinose, and possesses a
complete marginal ridge and well-defined zygidium in
the dorsal valve.

Discussion.—The Palmarito specimens tentatively
referred to Echinauris liumbona have been recovered
from four localities within the Palmarito Formation.
At localities | and 7, the specimens are preserved by
calcite permineralization. Consequently, while well-
preserved, they are difficult to prepare in internal de-
tail. The forms from localities 4 and 8 are silicified,
and internal details may be seen somewhat more clear-
ly. The silica replicas of locality 8 are quite coarsely
silicified, and fine details are commonly obscured. No
dorsal interiors were observed, but details were elu-
cidated from partially decorticated shells in which the
interior details were expressed in internal molds. At

locality 4, however, preservation was fine. A single |

partial dorsal valve was recovered, which, although

apparently incompletely silicified, showed a typical

omega-shaped costispiniferine cardinal process myo-

phore, without development of a zygidium.
Material.—

Articu-
Local- lated Dorsal Ventral Type of

ity Valves Valves Valves Preservation

1 5 _ — : F A Get

4 4 1 9 calcite permineralization
casts, with some adherent
silicified shell

y 93 > a calcite permineralization

8 10 — 1

casts, with considerable
amounts of adherent
silicified shell

Family PAUCISPINIFERIDAE
Muir-Wood and Cooper, 1960

Discussion.—The elevation of the Paucispiniferidae
to family rank (Cooper and Grant, 1975) places it on
equal footing with the Linoproductidae and the Mar-
giniferidae, with each of which it shares many char-
acteristics. The marginal ridge development of the
Marginiferidae is commonly found in association with
the zygidium, which feature is taken as the most sa-
lient diagnostic character of the family Paucispinifer-

19-28) from the Chochal Limestone of Guate- |
mala. There are, however, too few specimens of that —

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 67

idae (e.g., in Paucispinifera). Which of the morpho-
logic characters displayed by a shell shall be
designated as “‘genetically controlled’? and which
“environmentally controlled’’ is, in consideration of
forms with no living representatives, largely subjec-
tive. Internal characters are generally considered to
be less affected by environmental variability than are
external features, but this is not invariably so. In sum,
the assignment of all small Productacea bearing a zy-
gidium to the Paucispiniferidae is consciously subjec-
tive, and morphologically based. It is hoped that this
provisional classification may be refined by more ob-
jective future work.

Genus ANEMONARIA Cooper and Grant, 1969

Type Species.—Marginifera sublaevis R. E. King,
1931, p. 89, pl. 23, figs. 1Sa—c (non figs. 13, 14, 17 =
Anemonaria inflata Cooper and Grant, 1969, p. 8, pl.
5, figs. 28, 29)

Diagnosis.—

Outline subrectangular, widest at hinge, ears extended; profile
deeply concavo-convex; trail with distinct sulcus. Surface nearly
smooth except for numerous indistinct costellae on trail; spines few;
1 row on each lateral slope, scattered individual spines on trail and
visceral disc. Pedicle valve interior with small sessile cardinal pro-
cess with broad zygidium; breviseptum reduced. (Cooper and
Grant, 1969, p. 8)

Occurrence.—Anemonaria is known from the Bone
Spring, Cathedral Mountain and Road Canyon For-
mations of the West Texas region. In the present study
it has been recovered from localities 1, 10 and 11. The
ages represented by the occurrences of the West Tex-
as forms are not inconsistent with the other biostrati-
graphic indicators for those Palmarito localities.

Comparison.—Anemonaria is externally similar to
several genera of the Marginiferidae, but differs from
all in its possession of a zygidium. Its regularity of
form differentiates it from Polymorpharia Cooper and
Grant (1975), while its more subdued radial ornament
and distinctive spine pattern distinguish it from Lio-
sotella Cooper (in Cooper et al., 1953). In its fine,
obsolescent ornament, Anemonaria Cooper and Grant
(1969) resembles two species of Paucispinifera, P.
costellata Cooper and Grant (1975), and P. sulcata
Cooper and Grant (1975), in each of which the orna-
ment is somewhat more strongly expressed than in
Anemonaria. It may be that these forms are more
closely related to Anemonaria than their generic as-
signment would indicate.

Discussion.—The genus Anemonaria was originally
based on the type species Anemonaria inflata Cooper
and Grant (1969). Various forms which R. E. King

(1931) had named Marginifera sublaevis, but not the
holotype of that species, were included in the syn-
onymy of A. inflata. Later studies of King’s material
showed that the holotype of M. sublaevis was, after
all, conspecific with A. inflata. Therefore, by the rules
of nomenclature A. inflata, became a junior synonym
to A. (M.) sublaevis. Cooper and Grant (1975), there-
fore so named the species when they described it:
Anemonaria sublaevis (R. E. King, 1931).

Anemonaria sublaevis (R. E. King)
Plate 5, figures 20-27
Marginifera sublaevis R. E. King, 1931, p. 89, pl. 23, figs. 1S5a—c,
?16a, b, 19 (non figs. 13, 14, 17).
Anemonaria inflata Cooper and Grant, 1969, p. 8, pl. 5, figs. 28, 29.

Anemonaria sublaevis (R. E. King) Cooper and Grant, 1975, p.
1103, pl. 408, figs. 1-26.

Description.—Medium-sized, average sized for ge-
nus, having transverse rectangular to subpentagonal
outline and prominent triangular ears; widest at hinge.
Umbo small, low; posterior and anterior slopes steep;
greatest height at midvalve. Surface ornament of low,
obsolescent costellae; concentric rugae on ears.

Ventral valve deeply convex, with no delthyrium.
Ginglymus low, poorly developed. Ears flat, in plane
of commissure, separated from visceral slopes by sin-
gle row of halteroid spines. Additional halteroid spines
sparsely distributed over anterior and lateral slopes of
valve. Spines very rare along hinge or on ears. Entire
surface bearing very low obsolescent costellae; cos-
tellae about six in a five mm distance at midvalve,
rarely increasing anteriorly by intercalation; becoming
more apparent anteriorly. Commissure straight in an-
terior aspect. Anterior margin broadly sulcate, sulcus
arising anterior to umbo and continuing to commis-
sure.

Dorsal valve concave; greatest depth anterior to
midvalve. Surface generally smooth, non-spinose, but
anteriorly faintly costellate, costellae approximating
in size those of opposite valve. Ears small, triangular,
set at sharp angle to visceral slopes. Small rounded
triangular lophidium surmounting low, variably devel-
oped zygidium. Margin anteromesially indented, an-
teriorly producing low broad fold.

Ventral interior having indistinct, apparently striate,
paired diductor scars. Lateral walls of umbonal cavity
slightly swollen, bearing shallow horizontal grooves;
grooves articulating with zygidium of opposite valve.
Distinct marginal ridge arising in umbo, continuing
around shell near margin, evident anteriorly as low
step on interior surface of trail; crenulate across ears
on larger specimens. Inner surface smooth in smaller

68 BULLETIN 313

specimens; in larger specimens bearing faint costellae
which mirror external ornament.

Dorsal interior having small, stout cardinal process
without shaft; myophore omega-shaped to triangular
in posterior aspect, with small dorsally reflexed me-
dian lobe and broad lateral lobes. Mesial portions of
lateral ridges at base of cardinal process produced pos-
teriorly to form edge of zygidium, articulating with
grooves in ventral umbo. Muscle scars indistinct,
paired, narrowly elongate. Marginal ridges continu-
ous, arising at base of cardinal process, surrounding
visceral disc, distally geniculate across ears, distally
gradually sloping anteriorly and laterally. Surface an-
teriorly and laterally faintly costellate; ornament more
pronounced in larger specimens.

Measurements (in mm).—

Hinge Mid-

Length Width Width Height Material

Loca.ity 10

USNM 221214 12.0 10.7, 17.4, 6.7, (ventral valve)
USNM 221215 12.1, 13.3, 18.0, 5.2, (dorsal valve)
USNM 221216 13.7, 16.3, 20.1, 7.0, (dorsal valve)
USNM 221217 13.8 16.8, 18.7 8.9, (ventral valve)
USNM 221218 15.7 24.0, 22.1, 10.7, (ventral valve)

Occurrence.—Anemonaria sublaevis is known from
the Bone Spring, Cathedral Mountain and Road Can-
yon Formations of the West Texas region. In the Pal-
marito Formation it has only been recovered from lo-
cality 10, where it is rare. An Early Permian age, based
on its occurrence in North America, is not inconsistent
with other biostratigraphic indicators in the assem-
blage at locality 10.

Diagnosis.—Medium-sized Anemonaria having
slender halteroid spines and broad ventral sulcus.

Types.—Figured Specimens: USNM 221216—221220;
Measured Specimens: USNM 221214—221218.

Comparison.—Since A. sublaevis is the only
species of the genus, no infrageneric comparison is
necessary. It may be distinguished from any of the
species of Hystriculina Muir-Wood and Cooper
(1960), which it resembles in exterior ornament, by its
larger size and presence of a zygidium. It may be dis-
tinguished from species of Liosotella Cooper (in Coo-
per et al., 1953) by the coarser ornament of those
forms. It is probably very closely related to Paucispi-
nifera sulcata Cooper and Grant (1975), from which
it differs only in its more subdued radial ornament,
and to Paucispinifera costellata Cooper and Grant
(1975), which is distinguished by the high ridge bound-
ing its ventral apical muscle scars. It is easily distin-
guished from other similar forms in the Palmarito:

none of the Marginiferidae bear a zygidium. In addi-
tion, Echinauris bella Cooper and Grant (1975) is
smaller, has more spines on the ventral valve, and
bears dorsal spines as well, while Echinauris cf. E.
lappacea Cooper and Grant (1975) bears on each dor-
sal ear a thick brush of centripetally-directed thin
spines. The smaller umbo of Echinauris cf. E. lium-
bona Cooper and Grant (1975) in combination with
other, less obvious characters, immediately distin-
guishes it from A. sublaevis.

Discussion.—As stated above, Anemonaria sublae-
vis appears most closely related to Paucispinifera sul-
cata. A slight suppression of the costellae of the latter
would produce the appearance of the former. The Pal-
marito form is assigned to A. sublaevis with the de-
cided reservation that the classification system is, with
regard to these forms, beginning to reveal its arbitrary
nature to a great extent. There appears to be a contin-
uous range of variation in radial ornament between A.
sublaevis and P. sulcata, though, with a single excep-
tion (in the Road Canyon Formation of West Texas), —
they do not co-occur in a single bed in any region. It
is hoped that future studies of specimens from single ©
localities, showing a more complete range of infra-
population variation of these rare forms, will aid in
clarification of their relationships.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
10 4 4 25 fine silicification

Anemonaria? cf. A. sublaevis (R. E. King)
Plate 5, figure 28

cf. Anemonaria sublaevis (R. E. King) Cooper and Grant, 1975, p.
1103, pl. 408, figs. 1-26.

Types.—Figured Specimen: USNM 221221.

Discussion.—Four fragmentary specimens from lo-
cality 11 and one ventral valve from locality 1 exhibit ©
the characteristically subdued costellate exterior of -
Anemonaria sublaevis (R. E. King) and are of the —
proper size, shape and spine arrangement to warrant
such specific assignment. No complete dorsal valve —
has been recovered, however, in the absence of which —
the presence or absence of a zygidium cannot be as-
certained. Hence these specimens are only question-
ably assigned to the genus and species.

Material.—

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 69

Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation

1 1 — —
11 3 — 1

calcite permineralization
internal casts, with
considerable adherent
silicified ventral

valve shell material

Genus PAUCISPINIFERA Muir-Wood and
Cooper, 1960

Type Species.—Paucispinifera auriculata Muir-
Wood and Cooper, 1960, p. 320, pl. 122, figs. 1-16.

Diagnosis.—Usually transversely rectangular, zy-
gidium-bearing shells with poorly developed radial or-
namentation.

Occurrence.—Paucispinifera is known from the
West Texas area, in formations ranging in age from
Late Wolfcampian (Bone Spring Fm.) to Late Gua-
dalupian (Bell Canyon Fm.). A large species occurs in
the Guadalupian (Waagenoceras zone) of Las Deli-
cias, Coahuila, Mexico. In the Palmarito fauna it has
been recovered only from locality 8.

Comparison.—Paucispinifera is distinguished from
all genera outside the Paucispiniferidae by its having
a zygidium in the dorsal valve. Of the Paucispiniferi-
dae it is in general most closely related to Liosotella
Cooper (in Cooper et al., 1953), though certain
species of Paucispinifera may bear closer resem-
blance to other paucispiniferids. Liosotella is com-
monly strongly costate on both trail and visceral disc,
Whereas Paucispinifera commonly is variably orna-
mented longitudinally along the shell surface.

Discussion.—Within the Paucispiniferidae, Ane-
monaria Cooper and Grant (1969), Liosotella and
Paucispinifera appear to constitute a plexus of forms
which exhibit an almost continuous range of variation
in radial ornament. Future studies of large samples of
these forms are likely to reveal even more extensive
intergradation than is now evident. Two Palmarito
forms, Paucispinifera? cf. P. sulcata Cooper and
Grant (1975) and Anemonaria sublaevis (R. E. King,
1931) are here considered similar at the conspecific or
subspecific level, a relationship which their present
generic assignments do not indicate. The number of
specimens available for comparison in the Palmarito
| fauna, however, is insufficient to warrant placement

of Anemonaria in synonymy.

Paucispinifera? cf. P. suleata Cooper and Grant
Plate 5, figures 29-32

cf. Paucispinifera sulcata Cooper and Grant, 1975, p. 1137, pl. 418,
figs. 1-51; pl. 475, figs. 21, 22.

Description.—Medium-sized, small for genus, hav-
ing transverse rectangular to subpentagonal outline
and prominent triangular ears; widest at hinge. Umbo
small, low; posterior and anterior slopes steep; great-
est height at midvalve. Surface ornament of closely
spaced costellae (commonly six in 5 mm at midvalve).
Costellae weak on umbo, stronger anteriorly.

Ventral valve deeply convex, delthyrium obsolete.
Ears flat, slightly concave; separated from visceral
slopes by single row of halteroid spines. Additional
halteroid spines sparsely distributed over anterior and
lateral slopes. Spines very rare along hinge and on
ears. Entire surface bearing closely spaced costellae;
costellae increasing anteriorly by intercalation. Oc-
casional stronger costellae arising abruptly at halteroid
spine bases, continuing anteriorly to margin. Commis-
sure straight in anterior aspect. Anterior margin dis-
tinctly sulcate; sulcus broad, commonly V-shaped,
arising close to umbo and continuing to commissure.

Dorsal valve concave; greatest depth anterior to
midvalve. Surface faintly costellate, costellae stronger
anteriorly, spaced as on opposite valve. Ears large,
triangular, set at obtuse angle to umbonal slopes.
Small triangular spine surmounting apparent zygid-
ium. Margin anteromesially indented, producing low
broad fold anteriorly only.

Ventral interior unknown.

Dorsal interior having small trilobate cardinal pro-
cess with short shaft. Elongate triangular muscle scars
flanking slender breviseptum; breviseptum terminating
at midvalve. Row of small endospines anterior to end
of breviseptum, extending across valve. Brachial
ridges given off horizontally, lightly impressed.

Measurements (in mm).—

Dorsal
Valve Hinge Mid-
Length Length Width Width Height

LOCALITY 8
USNM 221222 7/3} 15.2 20.0, SESS 10.3,
USNM 221223 17.9 1335 29.40, 20.4 11.3
USNM 221224 18.3 h. 15.656 25.26, D226 10.2

Occurrence.—Paucispinifera sulcata, in the West
Texas region where it was defined, occurs only in the
Road Canyon Formation (Leonardian). The form here
questionably assigned to the species has been re-
covered in the Palmarito fauna from locality 8 where
it is rare. A Leonardian age for this locality in the
Palmarito is not inconsistent with other biostratigraph-
ic indicators.

Diagnosis.—Small Paucispinifera? with numerous
costellae and a wide deep sulcus.

70 BULLETIN 313

Types.—Figured Specimens: USNM 221222-221223;
Measured Specimens: USNM 221222-221224.

Comparison.—Apparent mature individuals of P.
auriculata Muir-Wood and Cooper (1960), P. inter-
media Cooper and Grant (1975), P. rara Cooper and
Grant (1975) and P. tumida Cooper and Grant (1975)
are larger in size than are similar ontogenetic stages
of P. sulcata, while ‘‘mature’’ specimens of P. inden-
tata (Girty, 1909) are smaller. P. costellata Cooper
and Grant (1975), which has radial ornament of the
same scale and form as P. sulcata, bears a distinctive
shelf surrounding the muscle attachment scars of the
ventral apex. P. latidorsata (Girty, 1909), P. quadrata
Cooper and Grant (1975), P. spinosa Cooper and
Grant (1975) and P. suspecta Cooper and Grant (1975)
have coarser radial ornament. P. transversa Cooper
and Grant (1975) is far more transverse in outline. P.
rectangulata Cooper and Grant (1975) is more square
in outline, and more geniculate in lateral aspect. P.
magnispina Cooper and Grant (1975) bears much larg-
er halteroid spines. P. parasulcata Cooper and Grant
(1975) has a very small ventral umbo, which projects
little beyond the hingeline. Anemonaria sublaevis (R.
E. King, 1931) is very similar to P. sulcata, yet may
be distinguished by its less well-defined radial orna-
ment. The presence of a zygidium in the dorsal valve
effectively distinguishes P.? sulcata from other Pal-
marito productaceans, except Anemonaria sublaevis.

Discussion.—see discussion of Anemonaria sublae-
vis.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
8 4 = — internal casts [dorsal

valves]; medium-grained
silicification
[ventral valves]

Family LINOPRODUCTIDAE Stehli, 1954
Subfamily LINOPRODUCTINAE Stehli, 1954

Genus HOLOTRICHARINA Cooper and Grant, 1975

Type Species.—Holotricharina hirsuta Cooper and
Grant, 1975, p. 1175, pl. 444, figs. 1-49; pl. 445, figs.
9-15; pl. 446, figs. 42-45.

Diagnosis .—

Linoproductidae related to Grandaurispina but having two sizes

of spines on the pedicle valve, non-costellate pedicle valve, but a
capillate brachial valve. (Cooper and Grant, 1975, p. 1175)

Occurrence.—Holotricharina occurs in the Cathe-
dral Mountain and Road Canyon Formations (Leo-
nardian) of the West Texas area. In the Palmarito For-
mation it has been recovered from localities 4, 8 and
13. A Leonardian age for these localities is not incon-
sistent with biostratigraphic evidence from other fau-
nal elements in the Palmarito.

Comparison.—Holotricharina may be distinguished
from most Overtoniidae by its distinctively linopro-
ductid cardinal process, and by the presence of fine
capillae on the dorsal valve. The linoproductid Grand-
aurispina Muir-Wood and Cooper (1960) has a more
regular spine arrangement, and lacks the dorsal radial
ornament of Holotricharina. Both Holotricharina and
Grandaurispina have laterally directed clusters of hal-
teroid spines arising below the ventral ears, but those
of Grandaurispina are distinctly coarser than the larg-
er body spines, whereas those of Holotricharina are
of about the same size. Holotricharina may be distin-
guished from all Linoproductidae except Grandauri-
spina by the presence of two distinct kinds of spines,
and by the absence of any radial ornament on the ven-
tral valve. The regularity of spine arrangement sets
apart the overtoniid Krotovia Frederiks (1928), as well
as the Asian Permian overtoniids Comuquia Grant
(1976) and Stictozoster Grant (1976). The Asian Perm-
ian genus Dyschrestia Grant (1976) is externally prob-
ably closest to Holotricharina, but its less transverse
outline, a cardinal process of more marginiferid than
linoproductid aspect and the lack of a dorsal brevisep-
tum clearly distinguish it from Holotricharina.

Discussion.—The two characters diagnostic of the
genus, dorsal radial capillae and a linoproductid car-—
dinal process are present only in the dorsal valve.
There is only a single fragmentary, apparently imma-
ture dorsal valve in the entire Palmarito suite of Holo-
tricharina. Nevertheless, the presence of two kinds of
ornament spines, as well as their irregular distribution
suggests assignment of the Venezuelan forms to the
genus Holotricharina.

Holotricharina hirsuta Cooper and Grant
Plate 5, figures 33-42

Holotricharina hirsuta Cooper and Grant, 1975, p. 1175, pl. 444, —
figs. 1-49; pl. 445, figs. 9-15; pl. 446, figs. 42-45.

Description.—Medium-sized, average for genus,
concavo-convex thin shells; outline transversely sub- |
rectangular to subtrigonal, interrupted by ears. Sides |
nearly straight to gently rounded in anterior aspect; |
anterior slope broadly rounded in lateral aspect. An-

terior commissure unfolded. Hinge narrower than |
|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 7\

midwidth; ears small, set at slight angle to body of
shell. Dense cluster of slender halteroid spines along
hinge, on and below ventral ears. Hinge spines di-
rected posteriorly and posteroventrally, others direct-
ed posterodorsolaterally, groups of spines commonly
crossing near ears. Additional suberect, anterodorsal-
ly directed halteroid spines scattered on anterior and
ventrolateral slopes. Finer anteriorly directed recum-
bent ornament spines on slopes and flanks of ventral
valve.

Ventral valve strongly and evenly convex in lateral
profile, flat-topped and steep-sided in anterior profile.
Beak small, pointed, umbo terminating above hinge-
line; umbo moderately swollen posteriorly, protruding
back beyond hingeline. Sulcus rarely developed.

Dorsal valve moderately to deeply concave; greatest
depth at or anterior to midvalve; steeper anteriorly
than laterally. Ears only slightly set off from body of
valve. Surface ornament of closely spaced concentric
rugae; rugae weak mesially and anteriorly, very strong
laterally and posterolaterally. Spines not observed;
surface otherwise apparently smooth.

Ventral interior having large, subcircular, paired
diductor scars developed subapically, bearing rela-
tively widely spaced narrow radial ridges. Surface oth-
erwise smooth.

Dorsal interior having small, slender bilobate car-
dinal process with minute median lobe, only slightly
deflected dorsally, and small shallow alveolus. Muscle
scars paired, apparently elongate suboval, separated
by slender breviseptum; breviseptum extending to
midvalve. Anterior half of valve finely endospinose.

Measurements (in mm).—

Dorsal
Total Valve Hinge Mid-
Length Length Width Width Height
Loca.iry 4
USNM 221225 = 12.7 11.3 10.8 16.7 pe 6.4
USNM 221226 14.8 12.3 11.0 Wi 2be 8.2
USNM 221227 16. Sn 14.1). 19:25. 21-dre 10.3 p56

USNM 221228 16.7 1S alive 19.2.4 2125) Wil
USNM 221229 17.7, 14. le 24.8.1, 26.6cn 10.7p.
Loca.ity 8

USNM 221230 14.5 11.2 13.2b¢ 18.2 7.8
USNM 221231 16.0, 12.4, 14.0), 20.8), 9.8

_ Occurrence.—Holotricharina hirsuta is known from
the Cathedral Mountain and Road Canyon Formations
of the West Texas region. This species was recovered
in the Palmarito Formation at localities 4 and 8. A
Leonardian age for these localities is not inconsistent
with the other faunal evidence available.

Diagnosis.—Medium-sized Holotricharina, some-
what transverse in outline, with numerous spines on
the body.

Types.—Figured Specimens: USNM 221225, USNM
21227, USNM 221228, USNM 221230, USNM
21232; Measured Specimens: USNM 221225-221231.

Comparison.—Holotricharina hirsuta is one of
three known species of the genus, all originally de-
scribed from the West Texas area. It is distinguished
from H. sparsa Cooper and Grant (1975) by the lesser
numbers of spines on that form, and from H.? sp. 1
of Cooper and Grant (1975), by its smaller size. The
Palmarito specimens assigned to H. hirsuta are some-
what larger than most of the West Texas individuals,
but are here considered to be within the range of vari-
ation in size of the species. In addition, the Venezue-
lan examples are commonly more transverse than are
their West Texas counterparts. This in itself might
seem a basis for separation of the Palmarito specimens
as a separate species, but it is considered that a larger
suite of Venezuelan specimens should be studied be-
fore such distinctions are attempted.

A second Venezuelan form, Holotricharina? sp. A,
is much larger than H. hirsuta. Its relationship to H.?
sp. 1 is uncertain, however, since only a single rela-
tively complete specimen of each is known.

Discussion.—Only a single fragmentary dorsal valve
of H. hirsuta was recovered in the present collections.
Small in size, the undifferentiated cardinal process and
presence of a shallow submyophoral alveolus indicate
it to be that of an immature individual. In all other
characters, however, the Palmarito specimens can be
assigned confidently to H. hirsuta.

2)
2

Material.—
Articu-

Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
4 4 — 4 fine silicification
8 3 1 = fine silicification;

internal cast of a
single dorsal valve

Holotricharina? sp. A
Plate 5, figures 43-45

Description.—Medium-sized, large for genus, thin,
convex ventral valve; in general form, outline and
spine arrangement as in H. hirsuta, except umbo
greatly swollen, produced further posterior to hinge-
line.

Ventral interior having slight ginglymus developed
mesially; surface otherwise smooth.

72 BULLETIN 313

Measurements (in mm).—

Dorsal
Total Valve Hinge Mid-
Length Length Width Width Height
Loca.ity 13
USNM 221233 26.5 16.4, 13.2 25.1 16.2bce

Occurrence.—Holotricharina? sp. A is known from
a single ventral valve recovered from locality 13. The
age of the assemblage at that locality, based on other
faunal evidence is latest Leonardian to Early Guada-
lupian.

Diagnosis.—Large Holotricharina? with swollen,
posteriorly produced umbo and two sizes of spines.

Types.—Figured and Measured Specimen: USNM
221233.

Comparison.—Only Holotricharina? sp. 1 Cooper
and Grant (1975) is of sufficiently large size to be con-
fused with H.? sp. A. It may be distinguished by the
presence of three distinct sizes of spines on the ventral
valve, as contrasted to the two sizes seen in H.? sp.
A. It may be that these two species are related more
closely than their designations would indicate. The
difference in type of spinose development would ap-
pear, however, to make this unlikely.

Discussion.—More formal designation of a species
name for this form should await study of additional
specimens of both it and related forms. Although frag-
ments of ventral valve apparently belonging to this
form were recovered at several localities, no recog-
nizable piece of dorsal valve was found. In the absence
of this, an unequivocal generic assignment cannot be
made.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
8 — — fine silicification
fine silicification

1 = Me
13 = =

fine silicification

1
10 — —_— 1
1 fine silicification

Family RETARIIDAE Muir-Wood and
Cooper, 1960

Genus KUTORGINELLA Ivanova, 1951

Type Species.—Kutorginella mosquensis E. A. Iva-
nova, 1951, p. 329.

Occurrence.—Kutorginella is known from latest
Mississippian and Pennsylvanian and Permian strata.

In the Mississippian it has been recognized only in
Europe, while in the Pennsylvanian it is reported from
both Europe and the North American midcontinent.
In the Permian its range extends to include the South
American continent as well (Samtleben, 1971).
Comparison.—Kutorginella may be distinguished
from Tubaria Muir-Wood and Cooper (1960) by the
wider hinge and distinctive long tubiform trail of that
genus; from Thamnosia Cooper and Grant (1969) by
the greater number of spines on species of that genus,
these especially concentrated on the anterior portions
of the trail and on the ears.
Discussion.—Antiquatonia Miloradovich (1945) is
externally quite similar to Kutorginella: indeed, they
differ only in the tubiform trail that may form a diag-
nostic character in the latter genus, but which all too
often is not preserved. Internally, however, the short-
er dorsal lateral ridges and the massive, sessile car-
dinal process clearly distinguish Antiquatonia. Vari-
ation in these very internal characters, however, in
the Venezuelan specimens, indicates the close rela-
tionship existing between the two genera, notwith-

standing their classification in two distinct families. —

Indeed, Sarytcheva (1971, p. 452) suggests that Ku-
torginella was derived in Early Pennsylvanian time
from an Antiquatonia-like ancestor, if not Antiqua-
tonia itself.

Kutorginella cf. K. umbonata
(Muir-Wood and Cooper)
Plate 6, figures 1-10

cf. Retaria umbonata Muir-Wood and Cooper, 1960, p. 231, pl. 70,
figs. 1-15.

ef. Kutorginella umbonata (Muir-Wood and Cooper) Cooper and
Grant, 1975, p. 1030, pl. 343, figs. 18-33; pl. 344, figs. 1-30.

Description.—Medium-sized, average for genus,
subplanoconvex to concavo-convex thin shells with
large body cavity; subtrigonal in outline; hinge equal
to or slightly less than midwidth; distinctly bilobate in
anterior aspect, with gently rounded flanks and dis-
tinct ventral sulcus; broadly domed in lateral aspect,
having steep anterior and posterior slopes. Both
valves geniculate. Umbonal regions strongly reticu-

late; anterior regions distinctly costellate. Valves_

sparsely spinose.

Ventral valve having low umbo, produced a small’

distance beyond hingeline. Ears thin, triangular, pla-

nar to somewhat convex exteriorly, set at acute angle’

to body. Umbo finely reticulate, having rugae stronger |
than costellae; rugae increasing in strength laterally to’
bases of ears, diminishing in strength anteriorly, ob- |
solescent at margin of visceral disc. Costellae fine,’
commonly seven to eight in a 5 mm distance at mid-|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 15

valve; rarely increasing anteriorly by splitting or in-
tercalation. Spines in single row roughly following
hinge; in more distinct row up flanks, not on spine
ridge, definitely mesial to break in slope between body
and ears; scattered over flanks, sulcus and trail, in-
creasing in size anteriorly; arising from crests of cos-
tellae. Distinct sulcus arising just anterior to umbo,
continuing to anterior commissure. Delthyrium tiny,
nearly obsolete.

Dorsal valve without spines, having planar to slight-
ly concave visceral disc margin. Low obscure fold de-
veloped on visceral disc, becoming more distinct on
trail, continuing to anterior commissure. Visceral disc
finely, strongly reticulate; trail evenly, finely costel-
late. Tiny pointed lophidium closing ventral delthyri-
um.

Ventral interior having low, wide ginglymus extend-
ing laterally onto ears. Submarginal ridges non-cren-
ulate, arising in umbo and continuing across bases of
ears as ear baffles; not internally striate. Umbonal
apex having sharp median ridge, separating paired,

striate, anteriorly expanded, rounded triangular diduc-
tor scars; median ridge succeeded anteriorly by raised
callus platform bearing paired elongate dendritic ad-
ductor scars. Diductors large, extending anterior of
ends of adductors. Remainder of surface broadly re-
flecting exterior ornament.

Dorsal interior having variable cardinal process,
with or without short shaft; commonly trilobed, with
expanded median lobe, lobe dorsally deflected and
mesially sulcate. Strong lateral ridges running along
hingeline and across bases of ears as ear baffles; ridges
sharply crested, but not crenulate or internally striate.
Broad base of cardinal process narrowing anteriorly
to form slender breviseptum; breviseptum continuing
to visceral disc margin, posteriorly separating poste-
riorly broad, elongate oval, dendritic adductor scars,
scars raised on callus platforms. Reniform, mesially
concave, lightly impressed, finely pitted areas poste-
rior and lateral to adductors. Remainder of surface
reflecting exterior ornament.

Measurements (in mm).—

Hinge Mid-
Length Width Width Height Material
LocaLity 4
USNM 221234 19.1). 30.06, 11.4, (dorsal valve)
USNM 221235 22. Spe — 30.0. 16.3 (articulated valves)
LocaLirty 8
USNM 221236 18.8 31.0), 6.3 (dorsal valve)
USNM 221237 23.0 — 13.8, (articulated valves)

Occurrence.—Kutorginella umbonata has been re-
covered, in the West Texas region where it was first
described, from the Cathedral Mountain and Road
Canyon Formations. In the Palmarito the form here
referred to the species appears at localities 1, 4, 7, 8
and 11. It is not abundant at any of these localities,
but is commonest at localities 4 and 8. The Leonardian
age of the West Texas forms is not inconsistent with
biostratigraphic evidence available as a guide to the
age of the Palmarito beds in which the related form
occurs.

Diagnosis.—Large Kutorginella with anterior mar-
gin thrown into a broad plication.
| Types.—Figured Specimens: USNM 221234—-221239;
|Measured Specimens: USNM 221234—-221237.

Comparison.—Kutorginella umbonata may be dis-
tinguished from K. robusta Cooper and Grant (1975)
by the larger size and more subtle sulcation of the
latter form; from K. sullivanensis (R. E. King, 1931)
by the distinctive spine distribution of that form; from
K. uddeni Cooper and Grant (1975) by the smaller
lateral spines of that form and its less well-defined

ventral sulcus. K. lasallensis (Worthen in Meek and
Worthen, 1873) is somewhat more strongly costellate
and has stronger, more numerous body spines; K. par-
vispinosa (Stehli, 1954) is a very similar form, but it
is not so distinctly sulcate ventrally. K. swbquadrata
(Cooper in Cooper et al., 1953) and K. occidentalis
(Cooper in Cooper et al., 1953) also lack this distinct
character. K. meridionalis (McKee, 1938) also is less
sulcate and has coarser costellation.
Discussion.—None of the Palmarito specimens
shows the distinctive trail development that is char-
acteristic of the Retariinae. No dorsal valve is pre-
served in its entirety, but the various pieces recovered
allow the formulation of a composite description. The
distinct deep ventral sulcus of the Palmarito form sets
it apart from most other species of the genus, except
K. umbonata. It does not appear to have as great a
development of the anterior marginal ring of dorsal
endospines as is common in K. umbonata in West
Texas. The distinctive row of spines across the flanks,
above the ventral ears, and across the anterior margin
is clearly seen only on a single Palmarito specimen,

74 BULLETIN 313

from locality 1. This specimen is unfortunately se-

verely crushed, and none but exterior details can be

discerned. For the above reasons, in addition to the

comparative rarity of the form in the Palmarito For-

mation, no definite species assignment can be made.
Material.—

Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
: : 7" o calcite permineralization
= a fine silicification; some
internal casts
7 = se | calcite permineralization
8 6 7 10 fine silicification; some
internal casts
11 2 1 3 medium-grained

silicification

Family ECHINOCONCHIDAE Stehli, 1954

ECHINOCONCHIDAE genus indeterminate
Plate 5, figure 46

Types.—Figured and Measured Specimen: USNM
221240.

Discussion.—A single specimen, comprised of the
partial interior of a dorsal valve and the adjacent apical
portion of the ventral valve of an unsilicified, apparent
echinoconchid brachiopod was recovered from an ho-
rizon high in the Palmarito Formation. It was not col-
lected during the present study, but forms part of the
Arnold Collection, now housed in the collections of
the National Museum of Natural History in Washing-
ton, D.C. This collection was assembled in the course
of a chiefly stratigraphically-oriented study under-
taken by H. C. Arnold in 1960 and later formally re-
ported (Arnold, 1966). The specimen, designated as
Ar. 981-R, was identified for that publication as
““? Bathymyonia cf. nevadensis (Meek),’’ by Helen M.
Muir-Wood. It has not, however, been formally de-
scribed.

The myophore and shaft of the cardinal process
have unfortunately been lost. Some diagnostic fea-
tures, however, remain in the dorsal interior. The thin
lateral ridges diverge slightly from the hingeline. The
muscle attachment area appears small and poorly im-
pressed. A thin median septum, flanked on either side
by a broader, low submedian ridge, extends to about
midvalve. Endospines, arranged in distinct concentric
rows beyond the septum, are assumed to reflect an

exterior ornament of concentric bands. The valve it-
self is only slightly concave and appears somewhat
geniculate anteriorly.

The ventral umbo appears to extend considerably
beyond the hinge.

The flattened dorsal valve, protruding ventral umbo,
obscure brachial ridges and most of all the apparent
concentrically banded ornament indicate proper as-
signment of this productacean to the Echinoconchi-
dae.

Measurements (in mm).—

Dorsal
Total Valve Hinge Maximum
Length Length Width Width
USNM 221240 37.4. SES: 29.6, 32:68
(Arnold Coll. Field
No. Ar. 981-R)

Family DICTYOCLOSTIDAE Stehli, 1954

Subfamily DICTYOCLOSTINAE Stehli, 1954

Genus PENICULAURIS Muir-Wood and Cooper, 1960

Type Species.—Peniculauris mckeei Muir-Wood
and Cooper, 1960, p. 280, pl. 100, figs. 1-7; pl. 101,
figs. 1-3 = Aulosteges subcostatus R. E. King, 1931,
p. 94, pl. 25, figs. 5-7.

Diagnosis.—Large semireticulate dictyoclostids
having an irregularly semireticulate visceral disc re-
gion, numerous small body spines on the visceral disc
and trail, and a brush of fairly slender but long halter-
oid spines on the ears. Numerous spines on the dorsal
valve. Cardinal process commonly large, spreading,
strongly trilobed.

Occurrence.—Peniculauris occurs in the West Tex-
as region in beds of from Late Wolfcampian (Skinner
Ranch Formation) to Late Leonardian (Road Canyon
Formation) age. It appears in the Chochal Limestone
(Leonardian) of Guatemala (Stehli and Grant, 1970),
identified as Kochiproductus? sp. (p. 32, pl. 11, fig.
11; pl. 13, figs. 1-7) and as Peniculauris mckeei Muit-
Wood and Cooper (1960) (Stehli and Grant, 1970, p.
32, pl. 11, figs. 7-10). In the Palmarito fauna it has
been recovered from localities 1 and 5. A Late Wolf-
campian to Late Leonardian age is consistent with
other biostratigraphic indicators for these localities.

Comparison.—Peniculauris closely resembles
Kochiproductus Dunbar (1955) externally, but may be

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 75

distinguished from that genus by its lack of an antron
in the base of the dorsal breviseptum, a diagnostic
feature of that buxtontid genus. Peniculauris some-
what resembles Squamaria Muir-Wood and Cooper
(1960), but lacks the auricular cluster of dorsal spines
diagnostic of that genus. Dasysaria Cooper and Grant
(1969), although similar in exterior ornament, lacks the
dorsal spines characteristic of Peniculauris.

Peniculauris subcostata latinamericana
new subspecies
Plate 6, figures 11-20

Peniculauris mckeei Muir-Wood and Cooper, Stehli and Grant,
1970, p. 32, pl. 11, figs. 7-10.

Kochiproductus? sp. Stehli and Grant, 1970, p. 32, pl. 11, fig. 11;
pl. 13, figs. 1-7.

Etymology of Name.—Engl. latin american + a.

Description.—Large, small to average for genus,
subrectangular to transverse in outline, concavo-con-
vex shells; widest at hinge, moderately to highly
domed in anterior aspect, with narrow sulcus and
steeply sloping flanks; anterior and posterior slopes
rounded in lateral aspect; geniculation pronounced.
Ears small, triangular to rounded, concave. Both
valves spinose, ventral valve considerably so.

Ventral valve deeply convex, elongate to trans-
verse; greatest height at venter; ovate to trapezoidal
in outline, quite variable. Beak small, low, raised only
slightly dorsal to hingeline; umbo comparatively small,
projecting short distance posterior to hingeline. Or-
nament of (1) concentric rugae, very strong along
hinge, weaker mesially, weakening anteriorly and be-
coming obsolete at venter, and (2) fine costellae, six
to eight in a 10 mm distance posterior to venter, eight
or more in a 10 mm distance on trail, becoming higher,
wider, more prominent from umbo to venter; at venter
abruptly splitting and thinning, becoming less promi-
nent toward anterior margin; increasing anteriorly in
each region by intercalation or splitting. Spines (1) in
ray originating at beak, diverging slightly from hinge,
spreading onto ears, there expressed as dense tuft of
slender halteroid spines, (2) dispersed over surface of
valve posterior to venter on locally raised intersec-

tions of costellae and rugae, increasing in size from
-umbo to venter, decreasing in size from venter ante-

riorly, very fine on trail, staggered on alternating cos-
tellae. Interspine portions of costellae distinctly lower,
each spine concentrically adjacent to saddle between
spines in next radial row. Trail repeatedly broken

some distance anterior to venter, commonly exhibiting
ten or more overlapping lamellar trails. Ears rounded
or triangular, sides anterior to ears indented or not,
quite variable. Distinct narrow sulcus, arising at umbo
and continuing to anterior margin, somewhat obscured
anteriorly by overlapping trails. Anterior commissure
broadly rounded, slightly indented mesially.

Dorsal valve concave, greatest depth at about mid-
valve, surface finely costellate umbonally, more
coarsely so anteriorly; finely rugose posteriorly, rugae
becoming obsolete anteriorly. Both radial and concen-
tric ornament less pronounced than on opposite valve.
Maximum degree of reticulation at midvalve. Fine
spines apparently present, rarely preserved, located
on intersections of costellae and rugae, as on opposite
valve. Ears gently rounded, concave; valve distinctly
geniculate. Low broad fold, originating in umbonal
hollow, broadening anteriorly, slightly indenting an-
terior commissure.

Ventral interior finely granulose, otherwise un-
known.

Dorsal interior having small, short-shafted, typically
dictyoclostid cardinal process; trilobate, median lobe
of myophore dorsally deflected, mesially sulcate, all
lobes crenulate. Lateral ridges arising at base of car-
dinal process, thinner and flatter laterally, diverging
slightly from hinge, crossing bases of ears as distinct,
somewhat raised, granulose to pustulose ridges, there
expressed as low step in shell surface, step continuing
around visceral disc. Broad base of cardinal process
thinning anteriorly, replaced by narrow, bladelike
breviseptum; breviseptum continuing beyond mid-
valve, terminating in slightly raised, slightly broad-
ened keel. Breviseptum flanked posteriorly by two
pairs of adductor muscle scars. Anterior pair coarsely
dendritic, elongate triangular, broadening anteriorly,
terminating short of brachial ridges; posterior pair
elongate triangular, coarsely dendritic, broadening an-
teriorly, adjoining anterior pair posterolaterally, the
two making a larger, more equilaterally triangular
composite muscle scar. Both marks raised on low cal-
lus platforms. Brachial ridges given off horizontally,
narrowly looped anteriorly. Remainder of surface (1)
irregularly pustulose posterior to brachial ridges, (2)
smooth to obliquely broadly ridged within brachial
ridge field, and (3) covered by low, conical, striate,
anteriorly directed, prostrate endospines mesial, an-
terior and anterolateral to brachial ridges. Endospines
smaller anteriorly, raised on low ridges mirroring ex-
ternal costellae. Exterior fold internally reflected as
anteriorly broadening mesial furrow, containing brev-
iseptum.

76 BULLETIN 313

Measurements (in mm).—

Costae in
Surface Hinge Mid- 10 mm on
Length Length Width Width Height trail

Locatity 1
USNM 221241 3939": 77 59.2, 46.3. 30.0, 9
USNM 221242 42.5 80 60.0), 50.4en 28.3, 8
USNM 221243 44.5. 76 71.6en Sean 26.2, 8
USNM 221244 47.0 82 52.6, 46.2 26.2 8
(holotype)
USNM 221245 48.0 95 50.0, 45.1 833 9

Occurrence.—Peniculauris subcostata latinameri-
cana n. ssp. is known at present only from Central
and South America. Stehli and Grant (1970) reported
it as P. mckeei Muir-Wood and Cooper (1960) and as
Kochiproductus? sp., from the Chochal Limestone
(Leonardian) of Guatemala. In the Palmarito fauna it
has been recovered only from locality 1. A single set
of extremely poorly preserved articulated valves,
questionably referred to the subspecies, was re-
covered from locality 5.

Diagnosis. —Medium-sized, variably shaped Peni-
culauris subcostata having fine costae; costae increas-
ing dramatically in number anterior to venter.

Types.—Holotype: USNM 221244; Figured Speci-
mens: USNM 221242, USNM 221244-221248. Mea-
sured Specimens: USNM 221241-221245.

Comparison.—Peniculauris subcostata latinameri-
cana n. ssp. is distinguished from P. bassi McKee
(1938), P. costata Cooper and Grant (1975), P. imitata
Cooper and Grant (1975) and P. subcostata subcos-
tata (R. E. King, 1931) by the larger mean size of the
costae in those forms; from P. peniculifera Cooper
and Grant (1975) by the smaller size of the mature
individuals of that species; from P. ivesi (Newberry,
1861) by the larger size and wider costae of that form;
from P. transversa Cooper and Grant (1975) by the
more transverse outline, larger ears, generally larger
size and coarser costae of that form.

Some of the West Texas specimens referred by Coo-
per and Grant (1975) to P. subcostata (R. E. King,
1931) show the anterior proliferation of small costae
peculiar to P. s. latinamericana, but not to the extent
or degree exhibited by the majority of the Palmarito
specimens. In addition the sample of the Venezuelan
population shows a far greater degree of variation in
form and outline than do the West Texas samples.
Although there is some overlap in size between the
two samples, it is readily apparent that the mean size
of mature individuals is greater in the West Texas
forms. Due to the extreme crushing suffered by most
of the Venezuelan specimens, comparative measure-

ments are not as impressive or consistent as they
might be. P. s. latinamericana n. ssp. is easily distin-
guished from other Palmarito Dictyoclostinae: from
Spinifrons grandicosta n. sp. by the broader costae
and large anteroventral halteroid spines of that form;
from Rugatia intermedia n. sp. and R. occidentalis
(Newberry, 1861) by the smaller size, coarser orna-
ment and aspinose dorsal valve of those forms.

Discussion.—Peniculauris subcostata, as clearly
elucidated by Cooper and Grant (1975), is in a peculiar
position. The type specimens, a holotype and three
paratypes, all fragmental valves, were mistaken by R.
E. King (1931) for Aulosteges, and were so considered
until additional preparation by Cooper revealed their
dictyoclostid affinities. The type specimens of Peni-
culauris mckeei, now in synonymy with A. subcos-
tatus, constitute a much larger, more representative
suite, yet the rules of taxonomic procedure determine
that comparisons should formally be made with the
primary types, not synonymous forms. The assign-
ment of the Venezuelan forms to P. subcostata latin-
americana, however, is entirely on the basis of com-
parisons made to Muir-Wood and Cooper’s now-
ineligible types and topotypic material, rather than to
King’s primary types.

The Guatemalan specimens here referred to P. s.
latinamericana represent extremes of the range of
variation of the Palmarito representatives. The two
specimens described (Stehli and Grant, 1970, p. 32) as
Kochiproductus? sp. (USNM 163587 and USNM
163588) are of a large form compared to most Palma-
rito specimens, with comparatively coarse costae, yet
they show the anterior proliferation of costae well.
The form and size of the larger specimen (USNM
163587) is similar to Palmarito specimen USNM
221243. The single shell (USNM 163575) described as
Peniculauris mckeei (Stehli and Grant, 1970, p. 32) is
more similar in size and form to a Palmarito specimen
USNM 221245. In the presence of the Venezuelan
material, it is not difficult to consider the Guatemalan
specimens as individuals deriving from the same
species population.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 77

Material.—
Locality Articulated Dorsal Ventral Type of Preservation
Valves Valves Valves
1 3 4 26 calcite permineralization

5 1 _

— coarse silicification

Genus RUGATIA Muir-Wood and Cooper, 1960

Type Species.—Productus (Dictyoclostus) parain-
dicus McKee, 1938, p. 241, pl. 46, figs. 5a—b.

Diagnosis.—Crudely reticulate and irregularly cos-
tate Dictyoclostidae, commonly with a cluster of large
thick halteroid spines on the ears and a few scattered
on the trail slope.

Occurrence.—Rugatia has been recovered from
Permian rocks in the Western United States, Central
America and, with this report, South America. In the
West Texas area where it has been most extensively
studied, it has been recovered from the Neal Ranch,
Skinner Ranch and Bone Spring Formations (Wolf-
campian) and the Cathedral Mountain and Road Can-
yon Formations (Leonardian). One species, R. occi-
dentalis (Newberry, 1861) is known from the Kaibab
Formation (Leonardian) of Arizona, and another, R.
andersoni Stehli and Grant (1970) from the Chochal
Limestone (Leonardian) of Guatemala. Two species,
one of them new, are here reported from the Palmarito
Formation of Venezuela. An Early Permian age for
the localities in which these species were found is not
inconsistent with other biostratigraphic indicators.

Comparison.—Rugatia may be distinguished easily
from Antiquatonia Miloradovich (1945), Spinarella
Cooper and Grant (1975) and Dasysaria Cooper and
Grant (1969) by the finer radial ornament of those
forms; from Peniculauris, Spinifrons Stehli (1954) and
Squamaria Muir-Wood and Cooper (1960) by the
presence of dorsal spines in those genera; from Cos-
tiferina Muir-Wood and Cooper (1960), Liosotella
Cooper (in Cooper et al., 1953) and Antiquatonia,
which also have a single row of halteroid spines arising
at the ventral umbo, but in none of which does the
row pass over the surface of the ears themselves, but
rather follows the break in slope between ears and
body; from Reticulatia Muir-Wood and Cooper
(1960), Peniculauris Muir-Wood and Cooper (1960)
and Stereochia Grant (1976) by the stronger reticula-
tion of those forms; from Peniculauris, Reticulatia,
Xestosia Cooper and Grant (1975) and Dasysaria by
their having a thick brush of spines on the ears, al-
though one species of Rugatia, R. paraindica (McKee
1938) does approach this condition. Nudauris Stehli
(1954) has a distinctive ornament of mixed costellae
and costae, not seen in Rugatia. Chaoiella Frederiks

(1933), unlike Rugatia, bears very weak radial orna-
ment.

Discussion.—It is in one sense unfortunate that the
type species of the genus Rugatia should be R. para-
indica. In making this form representative of the ge-
nus, it follows that a trait like the tuft of spines on the
ventral ears will be taken as pervasive in, rather than
indicative of the genus. In actuality however, most
species of the genus do not share this trait, but rather
have a single well-defined row of halteroid spines aris-
ing on the ventral umbo and running out onto the ears.

Rugatia intermedia new species
Plate 6, figures 21-28

Etymology of Name.—L. intermedia = intermedi-
ate.

Description.—Medium to large, large for genus,
concavo-convex transverse shells, trapezoidal in out-
line, widest at hinge, Highly domed, steep-sided in
anterior aspect; steeply sloping anteriorly and posteri-
orly in lateral aspect; both valves strongly geniculate.
Surface sparsely spinose. Umbonal regions and vis-
ceral discs semi-reticulate, having rugae stronger than
radial ornament; anterior and lateral regions strongly
costate. Distinct ventral sulcus; subtle dorsal fold.

Ventral valve deeply convex, having long acuminate
concave ears set at sharp angle to body of shell. Single
row of spines arising at umbo, increasing in size lat-
erally and posteriorly, diverging from hinge at low an-
gle; eight spines on each side of ventral umbo of spec-
imen having hinge width = 46.4 mm. Additional very
fine halteroid spines scattered on flanks and in sulcus;
spines quite large near anterior margin. Costae in-
creasing in size and strength anteriorly.

Dorsal valve concave, geniculate; triangular con-
cave ears set off from excavate visceral disc by low
oblique ridge. Surface dimpled, semireticulate on vis-
ceral disc, faintly rugose laterally and on ears; costae
more evident anterolateral of visceral disc.

Ventral interior having low, wide ginglymus and
open delthyrium. Bases of ear spines open to interior
below ginglymus. Narrow, elongate, dendritic adduc-
tor muscle scars, posteriorly striate, on high platform;
platform median in shell, narrowing anteriorly. Ad-
ductors separating large, anteriorly expanded, striate

78 BULLETIN 313

diductor scars. Adductor platform extending to op-
posite margin of dorsal visceral disc. Surface ante-
riorly and laterally faintly granulose, bearing low fur-
rows reflecting exterior ornament.

Dorsal interior having typical sessile dictyoclostid
cardinal process with broadly trilobate myophore;
median lobe mesially sulcate. Spinelike lophidium,
serving to close ventral delthyrium, produced dorsal-
ly. Lateral ridges serving mesially as articulatory pro-
cesses, following along hinge, becoming low, obsolete

on ears. Broad base of cardinal process narrow ante-
riorly, forming slender bladelike breviseptum; brevi-
septum anteriorly raised, terminating at anterior mar-
gin of visceral disc. Breviseptum flanked posteriorly
by large elongate triangular dendritic adductor scars,
set on callus platforms. Brachial ridges given off hor-
izontally, faintly impressed. Remainder of surface
semireticulate, rugose or costate, mirroring external
ornament.
Measurements (in mm).—

Surface Hinge Mid- Thick-
Length Length Width Width Height ness
Loca.ity 10
USNM 221249 26.3 50. 46.4 32.6 21.6 12.0,

(holotype)

Occurrence.—Rugatia intermedia occurs in the Pal-
marito Formation at localities 4, 8, 10 and 11. It isa
rare element at localities 4, 10 and 11, but common at
8. Similar forms, R. mckeei Cooper and Grant (1975)
of the West Texas region and R. andersoni Stehli and
Grant (1970) from the Chochal Limestone of Guate-
mala, are of Leonardian age. A Leonardian age for the
above localities is not inconsistent with other bio-
stratigraphic indicators.

Diagnosis.—Strongly costate, transverse Rugatia
with a single row of spines on the ventral ears and
distinctly reticulate visceral disc regions.

Types.—Holotype: USNM 221249; Figured Speci-
mens: USNM 221249-221252; Measured Specimen:
USNM 221249.

Comparison.—Rugatia intermedia is easily distin-
guished from R. incurvata (R. E. King, 1931) by its
larger adult size, and from R. paraindica (McKee,
1938) by the larger size and greater number of ear
spines of that form. It is more transverse in outline
and somewhat larger than R. convexa Cooper and
Grant (1975), and both larger and more strongly or-
namented than the other Palmarito species, R. occi-
dentalis (Newberry, 1861). It is probably most closely
related to R. mckeei, which is larger, has fewer spines
on the ears, and bears slightly less marked reticulation
on the umbonal regions, and to R. andersoni, which
is slightly smaller, less transverse, and bears weaker
costae that are less closely packed than on R. inter-
media. It is easily distinguished from other Palmarito
Dictyoclostinae: from Peniculauris subcostata latin-
americana n. ssp. by the larger size, more distinct
ornament and greater spine density of that form; from
Spinifrons grandicosta n. sp. by the dorsal fine and
anteroventral coarse spines of that form.

Discussion.—R. andersoni, R. intermedia and R.
mckeei evidently form a plexus within which specific
distinctions are cloudy. Since the gradation is chiefly
in shape and form, and because the Palmarito speci-
mens are largely fragmented, no ‘‘quantitative’’ esti-
mate of comparative similarity of R. intermedia to one
of the other two species is here attempted.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
4 1 l = fine silicification;
some casts
8 5 3 25 fine to medium
silicification;
some casts
10 1 — — fine silicification

11 1 1 3 fine silicification

Rugatia occidentalis (Newberry)
Plate 6, figures 29-35

Productus costatus Marcou (non Sowerby, 1827), 1858, p. 46, pl.
351i ok

Productus occidentalis Newberry, in Ives, 1861, p. 122, pl. 2, figs.
9, 10; R. E. King, 1931, p. 72, pl. 14, figs. 11, 12, 14 (non fig.
13 = Rugatia paraindica McKee, 1938, p. 239, pl. 46, figs. 1-4).

Productus (Dictyoclostus) meridionalis McKee in Stoyanov, 1936,
p. 523.

Rugatia occidentalis (Newberry), Cooper and Grant, 1975, p. 1082,
pl. 378, figs. 9-13.

non Productus occidentalis Newberry, Girty, 1909, p. 262, pl. 12,
figs. 4a—c [=Liosotella Cooper (in Cooper et al., 1953)].

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 719

Description.—Medium to large, average-sized for
genus, concavo-convex shells, subquadrate to elon-
gate rectangular in outline. Hinge width variable;
slightly less than to slightly more than midwidth.
Steep-sided, flat-bottomed, subrectangular in anterior
aspect; spiral, somewhat geniculate in lateral aspect,
having steep posterior slope and gently rounded an-
terior slope. Surface sparsely spinose. Umbonal re-
gions having faint concentric lirae and faint reticula-
tion; anterior regions broadly costate; costae low,
obsolescent. Variable ventral sulcus developed. Com-
missure straight in anterior aspect, gently rounded in
dorsal aspect. Delthyrium obsolete; low ginglymus
present.

Ventral valve deep, having small, compact, distinct-
ly concave ears. Single row of spines arising at umbo,
increasing in size laterally and posteriorly, diverging
from hinge at low angle; 11 spines on each side of beak
on specimen with hinge width = 39.0 mm. Additional
slender halteroid spines arising on crests of obsoles-
cent costae, scattered on slopes and in sulcus, becom-
ing more robust anteriorly. Costae arising and dying
out anteriorly by intercalation.

Dorsal valve gently concave, with small concave
ears, valve very sparsely spinose, spines rarely pre-
served. Ornament of faint concentric lirae.

Ventral interior faintly granulose near anterior and
lateral margins, otherwise not observed.

Dorsal interior having typical sessile dictyoclostid
cardinal process; trilobed myophore, with large, dor-
sally reflexed, mesially sulcate median lobe. All lobes
corrugate. Lateral ridges short, low, dying out mesial
to ears. Basal boss of cardinal process merging ante-
riorly into long slender breviseptum; breviseptum ter-
minating at anterior end of visceral disc. Anterior ad-
ductor scars elongate, dendritic, diverging anteriorly
from breviseptum; dendritic posterior adductor scars
reniform, concave mesially, located posterolateral of
anterior adductors. Both sets of scars set on slightly
raised callus platforms. Anterior and lateral portions
of valve not seen.

Measurements (in mm).—

Hinge Mid-
Length Width Width Height
Loca.ity 1
USNM 221253 DES 39.0cn 20.86 17.8,
USNM 221254 25.0, 30.0, 27.6, 15.0,
USNM 221255 28.3, 3PM 30.0, 16.5,
USNM 221256 32.8, 34.0cn 30.0, 19.7,

Occurrence.—R. E. King (1931) reported R. occi-
dentalis from various localities in the West Texas area,

in beds ranging in age from Late Wolfcampian to Early
Guadalupian. A subspecies, R. occidentalis parvauris
Cooper and Grant (1975), came from the Cathedral
Mountain Formation (Leonardian) in the same area.
Newberry (1861) collected the type Productus occi-
dentalis from the Kaibab Formation of the Grand Can-
yon region, Arizona, the age of which is Late Leo-
nardian. In the Palmarito Formation this form has
been recovered only from locality 1, for which an Ear-
ly Permian age is not inconsistent with other biostrati-
graphic indicators.

Diagnosis.—Elongate rectangular, steep-sided Ru-
gatia, with small concave ears and subdued ornament.

Types.—Figured Specimens: USNM 221253, USNM
221254, USNM 221256, USNM 221257; Measured
Specimens: USNM 221253-221256.

Comparison.—On the average, mature specimens
of Rugatia occidentalis are larger than similar onto-
genetic stages of R. incurvata (R. E. King, 1931), and
smaller than like stages of R. andersoni Stehli and
Grant (1970), R. mckeei Cooper and Grant (1975) or
R. paraindica (McKee, 1938). A similar form, R. con-
vexa Cooper and Grant (1975), is more tightly spiralled
than R. occidentalis. Although some of the Palmarito
specimens have the very small ears and short hinge of
R. occidentalis parvauris, these appear in the Vene-
zuelan specimens to intergrade with more typical R.
occidentalis, so that assignment to that subspecies is
not there justified. R. occidentalis may be distin-
guished from the other Palmarito species of the genus,
R. intermedia n. sp., by its smaller size, less promi-
nent, smaller ears, and the less pronounced reticula-
tion of the visceral disc regions of both valves. It may
as easily be distinguished from other Palmarito Dic-
tyoclostinae: from Peniculauris subcostata latinamer-
icana n. ssp. by the larger size, more distinct ornament
and greater spine density of that form; from Spinifrons
grandicosta n. sp. by the presence of dorsal fine and
anteroventral coarse spines in that form.

Discussion.—The range of variation of topotypic
specimens of R. occidentalis is not well-known. Be-
cause the Palmarito material is scanty and not well-
defined stratigraphically, it is better to assign the form
to an existing if incompletely understood species, than
to erect another incompletely known species in order
to justify real or imagined differences between the
two.

The Palmarito specimens were all recovered from
a limy shale, and in the process of compaction of that
rock had been extensively crushed. They were not
silicified and were removed mechanically from the en-
closing matrix. Thus it is difficult to ascertain the orig-
inal form of the shell with certainty.

80 BULLETIN 313

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
1 1 1 32 calcite permineralization
7 — = 1? calcite permineralization

Genus SPINIFRONS Stehli, 1954

Type Species.—Spinifrons quadratus Stehli, 1954,
p. 318, pl. 20, figs. 6-10.

Diagnosis.—Large Dictyoclostidae with a tuft of
large spines on the ears, large halteroid spines on the
anterior median part of the trail and slender hair-like
spines on the dorsal valve.

Occurrence.—Spinifrons is known from the Penn-
sylvania and Permian of the United States, though
only a single species of Pennsylvanian age is referred
to the genus (Stehli, 1954, p. 318). In the West Texas
region it appears to be largely limited to Late Wolf-
campian strata, although specimens questionably re-
ferred to Spinifrons spp. have been recovered from
strata as young as Guadalupian. Other biostratigraphic
indicators in the Palmarito Formation suggest that the
age of the Venezuelan representatives of the genus lies
in the Leonardian, if not Guadalupian.

Comparison.—Spinifrons is easily distinguished
from other genera within the Dictyoclostinae: from
Antiquatonia Miloradovich (1945), Spinarella Cooper
and Grant (1975) and Dasysaria Cooper and Grant
(1969) by the finer radial ornament of those genera;
from Squamaria Muir-Wood and Cooper (1960) by the
presence of a brush of dorsal ear spines in that genus;
from Reticulatia Muir-Wood and Cooper (1960) and
Rugatia Muir-Wood and Cooper (1960) by the absence
of dorsal spines of any form in those genera; from all
others by the presence of large halteroid spines, not
only in a dense brush on the ears, but also in a con-
spicuous group anteromesially on the ventral sulcus
and near the ventral anterior margin.

Discussion.—Spinifrons is easily identified if well
preserved: if the dorsal spines and anteroventral hal-
teroid spines are poorly preserved and (or) not ob-
served, recognition of the genus can be very difficult.
The specimens here questionably assigned to Spini-
frons grandicosta n. sp., all poorly or incompletely
preserved, had been initially assigned to the genus
Peniculauris Muir-Wood and Cooper (1960), on the
basis of the preserved spine arrangement. Later rec-
ognition of similarity of form and other diagnostic
characters permitted assignment to Spinifrons.

Spinifrons grandicosta new species
Plate 7, figures 1-10

Etymology of Name.—L. grandis = grand, large +
L. costa = rib.

Description.—Large, larger than average for genus,
concavo-convex transverse shells; subpentagonal in
outline, having small, rounded triangular ears. Ante-
rior commissure gently rounded, not appreciably in-
dented mesially. In anterior aspect moderately domed,
with steep flanks; in lateral aspect tightly spiralled,
geniculate, having steep anterior and posterior flanks
and subparallel visceral disc and trail surfaces. Orna-
ment of rugae and costae producing faintly reticulate
surface posteriorly. Ventral valve spinose; dorsal
valve apparently so, but spines not preserved. Umbo
small, low, not protruding appreciably posterior or
dorsad to hingeline. Slight fold and sulcus develop-
ment.

Ventral valve deeply convex; greatest height at
about midvalve. Ears curving smoothly into flanks.
Surface ornamented by (1) irregular concentric rugae,
arising at umbo, becoming obsolete ventral of hinge,
posterior to venter, (2) irregular costae, weak at umbo,
but increasing in strength anteriorly, increasing in
number by irregular bifurcation and intercalation, or —
arising abruptly anterior of spine bases, continuing to ©
anterior margin; four to five in a 10 mm distance on
trail. Spines (1) in ray divergent from hinge, terminat-
ing laterally in sparse tuft of robust halteroid spines
on ears, (2) as smaller ornament spines scattered over
flanks and sulcus, on crests of costae at intersections
with rugae or not, (3) as large, heavy erect halteroid
spines on crests of costae near anterior margin, con-—
centrated in sulcus and anteromesial portions of shell.
Anterior commissure gently rounded, slightly indented
in dorsal aspect. Minute open triangular delthyrium
present.

Dorsal valve deeply concave; greatest depth at or
slightly anterior to midvalve. Ears slightly set off from
visceral disc by low rounded oblique ridge. Low ob-
solescent rugae, originating at umbo, covering visceral
disc. Obsolescent costae, arising as fine costellae at
umbo, appearing distinctly only on trail, there as broad
folds separated by narrower furrows. Apparent spine
bases scattered over visceral disc and trail, increasing |
in size distally. Anterior margin gently rounded, very
slightly mesially indented. Low fold arising at umbo,
continuing across visceral disc and trail to anterior
margin.

Ventral interior having flattened ears, set off from
visceral cavity by diductor-bounding ridges; ridges ex-
tending about one-half distance across bases of ears. | |
Diductor muscle scars large, elongate triangular, |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 81

striate and flabellate, anteriorly broadening, inset into
valve floor. Diductors separated posteromesially by
narrowly elongate, paired, dendritic adductor muscle
scars, raised on slight callus platforms. Interior of ears
faintly granulose, remainder of surface minutely en-
dospinose, having furrows on trail reflecting exterior
costation.

Dorsal interior having typical dictyoclostid cardinal
process: trilobed, with dorsally deflected mesially sul-
cate median lobe; lateral lobes considerably reduced.
Lateral ridges diverging slightly from hinge; appearing
to continue across ears as low, distinct ridges; contin-
ued at geniculation to about midvalve as low rounded

step in shell surface. Base of cardinal process narrow-
ing anteriorly to form long slender breviseptum; brev-
iseptum continuing to point of geniculation, there ter-
minating in high, very thin blade. Paired, broadly
triangular, dendritic adductor muscle scars posteriorly
flanking breviseptum, slightly raised on thin callus
platforms. Brachial ridges given off horizontally; nar-
rowly looped anteriorly. Surface granulose posterior
to brachial ridges, smoother within brachial ridge
loops; remainder minutely endospinose; endospines
semierect, anteriorly directed, on trail arising from
costae; costae reflecting exterior ornament.
Measurements (in mm).—

Dorsal
Surface Valve Hinge Mid- Thick-
Length Length Length Width Width Height ness
Loca.ity 13
USNM 221258 42.9, —_— = 60.6.1 46. De —
USNM 221259 43.8 90. 33.4 63.6, 48.4 32.6. 15.6,

(holotype)

Occurrence.—Spinifrons grandicosta n. sp. occurs
at locality 13 in the Palmarito Formation. A single ven-
tral valve questionably referred to the species has been
recovered from locality 8. The West Texas form prob-
ably most closely related to S. grandicosta, S. quad-
rata Stehli (1954), is largely limited to the lower Bone
Spring Formation, of Late Wolfcampian age. This age
is older than that inferred for the localities in the Pal-
marito in which S. grandicosta has been identified.

Diagnosis.—Larger than average subquadrate Spi-
nifrons having coarse, extremely irregular ornament,
robust halteroid spines and relatively low profile in
anterior aspect.

Types.—Holotype: USNM 221259; Figured Speci-
mens: USNM 221258-221260; Measured Specimens:
USNM 221258, USNM 221259.

Comparison.—Spinifrons grandicosta is distin-
guished from S. portlockianus (Norwood and Pratten,
1855) and S. delicatula Cooper and Grant (1975) by
the smaller size of the mature specimens of those
species. S. magna Cooper and Grant (1975) is larger,
more quadrate, and has relatively finer halteroid
spines on the ears. The most similar form, S. guadratus
is smaller, more finely and regularly ornamented, more
steeply domed, and has lateral ridges that do not. ex-
tend across the bases of the ears in the dorsal interior.

It is easily distinguished from other Palmarito Dic-
tyoclostinae: from Peniculauris subcostata latinamer-
icana n. ssp. and R. occidentalis (Newberry, 1861) by
the smaller spines on the trail of those forms; from
Rugatia intermedia n. sp. and R. occidentalis by the

smaller size, less quadrate outline, and lack of tufts of
ear spines in those forms.

Material.—
Articu-
Local- lated Dorsal Ventral Type of

ity Valves Valves Valves Preservation

8 1 ~ 3 medium to coarse
silicification

13 1 = 1 fine silicification

Spinifrons? cf. S. grandicosta new species
Plate 7, figures 11-15

Description.—Large, average-sized for genus, con-
cavo-convex transverse shells; subpentagonal in out-
line. Lateral slopes gently rounded, venter slightly in-
dented in anterior view; anterior and posterior slopes
rounded in lateral view. Ears large, rounded, merging
smoothly into visceral mass. Umbo low, small, pro-
truding only slightly dorsal and posterior to hingeline.
Distinct costae arising as costellae at umbo, increasing
anteriorly in size, and in number, by intercalation and
bifurcation; anteriorly of venter quite strong, coarse.
Rugae, distinct posteriorly, becoming somewhat
weaker anteriorly, rather abruptly dying out at venter.
Both valves spinose.

Ventral valve broadly convex, geniculate; greatest
height at or anterior to midvalve; coarsely reticulate
from umbo to venter; rugae abruptly disappearing at

82 BULLETIN 313

venter; costae anterior to venter coarse, four to five
in a 10 mm distance on trail, separated by furrows
about equal in width to costae. Ears broad, slightly
flattened; body not appreciably indented anterior to
ears. Small triangular open delthyrium. Spines (1) in
ray from umbo to ears, (2) as dense tuft of coarse
halteroid spines on ears, (3) as fine spines scattered
over surface of visceral disc on intersections of rugae
and costae. Spines on locally raised portions of costae,
staggered so that no spine is concentrically adjacent
to one on neighboring costa. Spines apparently rare to
absent on trail. Distinct broad mesial sulcus arising at
umbo, continuing to indent anterior commissure. Bro-
ken-off trails common anteriorly, there forming dis-
tinct overlapping lamellae.

Dorsal valve slightly to deeply concave, visceral
disc planar to slightly concave, junction with trail dis-
tinctly geniculate. Ears flattened. Visceral disc finely
reticulate; rugae fine, rather uniform; costae fine um-
bonally, increasing anteriorly in size; in number by
intercalation. Trail broadly costate, there commonly
bearing four to six rounded costae in a 10 mm distance,
costae separated by considerably narrower furrows.
Narrow fold arising anterior to shallow umbonal hol-
low, continuing to, and indenting anterior margin.
Fine, delicate, erect spines scattered over visceral disc
in rough quincunx pattern; absent or not preserved on
trail. Minute lophidium, aiding in closure of ventral
delthyrium.

Ventral interior having raised elongate median cal-
lus platform bearing paired dendritic adductor muscle
scars; platform flanked by larger, anteriorly broad-
ened, radially striate, triangular diductor muscle scars
inset onto valve floor and lateral umbonal walls. Dis-
tinct muscle-bounding ridges, non-crenulate, arising in
umbo, running along posterolateral margins of diduc-
tor scars, extending about one-half way across bases
of ears, overhanging visceral cavity. Distinct curved
ginglymus present. Ears slightly concave, smooth.
Surface otherwise minutely pustulose to finely pitted.

Dorsal interior having typical sessile to semi-erect,
posterior- to posterodorsal-facing cardinal process
myophore; myophore trilobate, with larger median
lobe dorsally deflected, mesially sulcate. Shaft short
to obsolete. Lateral ridges running along hinge, di-
verging from hinge to bend across bases of ears; an-
terior extent or continuation not observed. Broad base
of cardinal process narrowed anteriorly to form slen-
der low breviseptum; breviseptum terminating nearly
opposite anterior margin of dorsal visceral disc in
broadened, raised blade. Paired, dendritic, broadly tri-
angular adductor scars posteriorly flanking brevisep-
tum; scars bounded posterolaterally by low, incipient
secondary septum, this arising from broad base of car-

dinal process. Coarse, raised brachial ridges given off
horizontally from anterior end of adductor scars, nar-
rowly looped anteriorly.

Measurements (in mm).—

Hinge Mid- Thick-
Length Width Width Height ness

Loca.irTy 11
USNM 221261 40, . 30.5, 47.6), _— 13.1,
USNM 221262 — 67.2, 46.5. 34. 19.0,

Occurrence.—Spinifrons? cf. S. grandicosta n. sp.
occurs in the Palmarito fauna at localities 3, 4 and 11.
It is rather rare at localities 3 and 4 and common at
locality 11.

Diagnosis.—Like Spinifrons grandicosta, but aspi-
nose or rarely spinose on the trails.

Types.—Figured Specimens: USNM 221262-—221266;
Measured Specimens: USNM 221261, 221262.

Discussion.—Because it lacked the anteroventral
trail spines diagnostic of Spinifrons, I first assigned
this form to Peniculauris Muir-Wood and Cooper
(1960). Later comparison with specimens assigned to
S. grandicosta, showed great similarities, but no exact
correspondence. In the absence of any traces of ven-
tral trail spines, these forms can only questionably be
assigned to Spinifrons, although they share many of
the specific characters of S. grandicosta.

Material.—

Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
3 l a = fine silicification
4 l - = medium to coarse
silicification
11 7 _— — fine to coarse

silicification

Suborder OLDHAMINIDINA Williams, 1953
Superfamily LYTTONIACEA Waagen, 1883
Family LYTTONIIDAE Waagen, 1883

Discussion.—Worldwide distribution of lyttontid
brachiopods made possible prediction of their pres-
ence in rocks of proper age and lithotype in Venezue-
la. Their previous absence from reports and faunal
lists was probably due, among many other factors, to
the search for fossils chiefly in rocks that preserved
soft-bottom assemblages. The environments repre-
sented by such rocks lacked the hard substrate nec-
essary for the cemented attachment of the lyttontids
(Hoover, 1975).

Genus COLLEMATARIA Cooper and Grant, 1974

Type Species.—Collemataria elongata Cooper and
Grant, 1974, p. 137, pl. 139, figs. 11, 17-20; pl. 170,

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 83

figs. 1-16; pl. 171, figs. 1-18; pl. 172, figs. 1-16; pl.
173, figs. 1-40; pl. 181, figs. 12-15; pl. 183, figs. 22-
23; pl. 191, fig. 10.

Diagnosis.—Usually large Lyttoniidae having pro-
gressive lateral septa, posterior callus flap for attach-
ment, and hinge at margin of cowl.

Occurrence.—Specimens referable to Collemataria
have been reported to date only from the West Texas
area, in rocks of from Wolfcampian (Skinner Ranch
Formation) to Guadalupian (Bell Canyon and Capitan
Formations) age.

Comparison.—Collemataria might best be called
the “‘North American Leptodus,’’ since it includes
many of the Western United States species formerly
assigned to that genus. Many of these species were
removed from Leptodus Kayser (in Richthofen, 1882)
upon recent study of type specimens of the genus that
revealed the presence of a ventral diductor muscle at-
tachment area in that form. This attachment, bounded
by shell plates, is a feature not seen in many of the
American forms. The genus Collemataria was there-
fore erected to house these Leptodus-like forms which
had no well-defined muscle attachment areas.

Collemataria may be distinguished from all Lytto-
niidae except Leptodus and Petasmaia Cooper and
Grant (1969) by the manner of attachment to the sub-
strate. In these three genera, the callus shell growth
above the ventral valve hinge is posterior, forming a
flap, which is reflexed ventrally and joins with the apex
as a secondary site of shell attachment. The other gen-
era of the Lyttoniidae have a similar shell structure,
but it grows anteriorly, forming a cowl, and giving the
entire shell a more conical aspect. Both Leptodus and
Petasmaia have so-called ‘‘dental plates’’ (muscle
field bounding ridges), located at either side of the
midline in the ventral interior apex. While those of
Petasmaia are quite strong and well-defined, those of
Leptodus are less so. Collemataria rarely exhibits any
indication of the scope of its diductor musculature,
beyond the shape and form of its cardinal process.

Collemataria venezuelensis new species
Plate 7, figures 16-23

Lyttoniid specimen of Hoover, 1975, p. 152, text-fig. 2.

Etymology of Name.—Venezuela + L. -ensis = at
the place of.

Description.—Small, commonly low, relatively
broad, ostreiform shells having irregular, concentri-
cally wrinkled exterior. Attached at apex and by
everted posterior callus flap, cicatrix commonly at
considerable angle to plane of shell. Valve floor flat or
concave, with margins commonly flexed dorsally.

Ventral interior having narrow, straight hinge, inset

at junction of valve and relatively large posterior flap;
ventrally bearing small symmetrical articulatory pro-
cesses. No apparent muscle scars or plates defining
muscle field. Seven to twelve, commonly eight to nine
longitudinally compressed, angustilobate to solidisep-
tate septa of subuniform height, having posteriorly
fluted or beaded faces. Posteriormost two to three lat-
eral septa approaching anguliseptate condition. Well-
defined median ridge extending from just anterior to
hingeline as sharp solidiseptate form, commonly me-
sially grooved; narrowly bifurcate anteriorly.

Dorsal valve small, thin, having narrow straight
hinge; commonly bent at high (nearly 90°) angle near
bifurcation to conform to similar deflection in ventral
valve. Surface smooth, rounded, having low median
depression extending anteriorly from hinge to bifur-
cation. Bifurcation persistent, not narrowed or healed
anteriorly. Lateral lobes separate, distinct, not healed
laterally.

Dorsal interior having small, commonly eccentri-
cally positioned, bilobate to quadrilobate cardinal pro-
cess, set on very short shaft. Narrow median ridge
arising at base of cardinal process, doubled or longi-
tudinally grooved and broadening anteriorly up to bi-
furcation. Lobes concave, commonly having inner lin-
ear or beaded marginal rim.

Measurements (in mm).—

Maximum
Length Width Height
LOCALITY 6
(block A)
USNM 221267 16.3, 20.8), 6.8),
USNM 221268 20.1, 20.6, Sth
USNM 221269 26.6, 20.7, 14.0,
(holotype)
USNM 221270 32.4, 24.4, 5.8},

Occurrence.—Collemataria venezuelensis n. sp. has
only been recovered from locality 6, block A. Blocks
B and C from the same locality contain no traces of
the form, indicating its patchy distribution. The most
similar previously described species of the genus, C.
spatulata Cooper and Grant (1974) is known from the
Bell Canyon and Capitan Formations (Guadalupian)
of West Texas. Such an age assignment is not incon-
sistent with that provided by other biostratigraphic in-
dicators for this Palmarito locality.

Diagnosis.—Small Collemataria, having discrete
low lateral lobes and narrow, uniform lateral septa.
Ventral valve cemented to substrate near beak only;
remainder of valve commonly at a high angle to sub-
strate.

Types.—Holotype: USNM 221269; Figured Speci-

84 BULLETIN 313

mens: USNM 221269-221274; Measured Specimens:
USNM 221267-221270.

Comparison.—The Palmarito specimens are easily
differentiated from other species of Collemataria. C.
americana (Girty, 1909) is similar in overall appear-
ance but tends to be larger and to have a more gran-
ulose interseptal area in the ventral interior than does
C. venezuelensis. C. batilliformis Cooper and Grant
(1974) is typically anteriorly constricted, in some cases
to such a degree that the anterior margin is tubiliform.
C. elongata Cooper and Grant (1974) and C. gregaria
Cooper and Grant (1974) are much larger than C. ven-
ezuelensis: the former also differs in its higher lateral
septa, while the lateral lobes of the dorsal valve are
commonly merged in the latter. C. irregularis Cooper
and Grant (1974) in general has a deeper shell, with
greater development of the cowl. C. marshalli (Stehli,
1954) has thick, high lateral septa, quite unlike the
narrow, more uniform ones of C. venezuelensis. C.
platys Cooper and Grant (1974) is commonly cemented
to the substrate over much of its ventral surface, un-
like C. venezuelensis, in which attachment is limited
to the apex and posterior flap, while the remainder of
the shell lies at a considerable angle to that plane. C.
spatulata is commonly somewhat larger and flatter
than C. venezuelensis, though of the West Texas
forms it is the most similar to C. venezuelensis.

Discussion.—The present collection of C. venezue-
lensis consists of just over forty specimens, many of
them fragmentary. Only two sets of articulated valves
were recovered, and only a single set is separable so
that the interior may be examined. Most specimens
are missing much of the lateral and anterior margins.

The remainder of the brachiopod assemblage col-
lected from locality 6, blocks A, B and C consists of
small forms. Some of these may be immature, though
in some cases distinct evidence of maturity is present
(e.g., loop development in Terebratulida). C. vene-
zuelensis is by far the largest brachiopod present, al-
though it is smaller than many previously described
lyttoniids. Although some of the specimens bear ju-
venile characters (predominance of angustilobate, as
opposed to solidiseptate septa; small, commonly bi-
lobate, rather than quadrilobate cardinal process myo-
phore), sufficient numbers of specimens are present to
demonstrate that mature individuals are also repre-
sented.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
6 (block A) 1 10 44 fine silicification

Order RHYNCHONELLIDA Kuhn, 1949
Superfamily RHYNCHONELLACEA Gray, 1848
Family PONTISIIDAE Cooper and Grant, 1976a

Discussion.—This family, created from part of Wel-
lerellidae (sensu lato) includes forms which externally
resemble Wellerella Dunbar and Condra (1932) (sensu
stricto) but lack the dorsal median septum character-
istic of wellerellids. In Wellerella (sensu stricto) how-
ever, this septum is limited to the apical portion of the
valve. In the National collections, some specimens
identified as W. girtyi Cooper and Grant (1976a) have
such a small dorsal median septum that it cannot readi-
ly be discerned; in the same collection, specimens of
Pontisia stehlii Cooper and Grant (1969), an external
homeomorph of W. girtyi, have a ‘“‘median ridge”’ that
rises apically to join the underside of the hinge plate
in the dorsal valve, a condition most atypical for that
genus. Cooper and Grant (1976a, p. 2019) state

In old specimens [of Pontisia] the low [median] ridge often swells
to a boss posteriorly under the hinge plate. This simulates Wellerella
but the boss is never a septum although it may help to support the
hinge plate.

While the Pontisiidae and Wellerellidae appear to
intergrade in terms of development of the median sep- —
tum, they include too diverse a group of forms to be |
considered as a single family. Hence the somewhat
artificial distinction is necessary, to allow recognition
of workable, if not strictly valid family groupings. The
spatio-temporal continuum of organic life may provide
a more-or-less continuous gradation of phenotypes.
When such a data set is incomplete, distinctions ap-
pear clearcut; as sampling becomes more comprehen-
sive however, the sharp edges of differentiation be- |
come somewhat more rounded.

Genus PONTISIA Cooper and Grant, 1969

Type Species.—Pontisia stehlii Cooper and Grant,
1969, p. 13, pl. 4, figs. 7-10.

Diagnosis.—Pontisiids with hinge plate similar to
that of Wellerella but not supported by a median sep-
tum.

Occurrence.—Pontisia is known from North, Cen-
tral and South America, and has been reported in
Thailand (Grant, 1976). Its range almost certainly is |
greater than this, but since familial and generic dis-
tinctions are based upon internal characters, many ©
previously described forms [e.g., Wellerella (sensu —
lato)] cannot properly be reassigned until extensive |
additional preparation has been undertaken. |

Comparison.—Pontisia may be distinguished with |
ease from other genera of the Pontisiidae: Lirellaria |
Cooper and Grant (1976a) is costellate, while Divari- |

|
|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 85

costa Cooper and Grant (1969) has bifurcating costae;
a number of the median costae of the dorsal fold of
Antronaria Cooper and Grant (1976a) are character-
istically depressed; Aphaurosia Cooper and Grant
(1976a) has irregular radial ornament and a more
rounded outline; species of Acolosia Cooper and
Grant (1976a) are commonly smaller and smoother
than those of Pontisia; Anteridocus Cooper and Grant
(1976a) has only rudimentary dental plates, in contrast
to the strong ones seen in species of Pontisia. As stat-
ed above, Pontisia may be distinguished from most
species of Wellerella, by the presence of a dorsal me-
dian septum in those forms. Some species of Pontisia
may resemble Allorhynchus Weller (1910), in that the
radial ornament arises at or just anterior to the beaks,
but the presence of an undivided hinge plate clearly
permits their assignment to Pontisia.

Pontisia stehlii Cooper and Grant
Plate 7, figures 39-48

Pugnoides texanus R. E. King (non Shumard, 1860), 1931, p. 108,
pl. 34, figs. 5-9.

Pugnoides elegans R. E. King (non Girty, 1909) part, 1931, p. 106,
pl. 33, figs. 12, 13; pl. 34, fig. 4 (non figs. 2, 3).

Pontisia stehlii Cooper and Grant, 1969, p. 13, pl. 4, figs. 7-10.

Pontisia stehlii stehlii Cooper and Grant, 1976a, p. 2027, pl. 517,
figs. 21-25, 38-47; pl. 533, figs. 40-61; pl. 534, figs. 1-49; pl. 552,
fig. 14.

Description.—Small to medium sized, average to
large for genus, unequally biconvex, in mature ex-
amples somewhat bulbous, having rounded trigonal to
subpentagonal outline; dorsal valve much deeper than
ventral. Lateral profile subtrigonal; anterior commis-
sure uniplicate; fold low to moderately high, common-

ly beginning about 5 mm anterior to dorsal beak; pro-
file flattened near beak, abruptly convex anteriorly;
sulcus shallow to moderately deep, commonly begin-
ning about 9 mm anterior to ventral beak. Anterior
face commonly rounded in lateral view, rarely slightly
facetted in mature to gerontic individuals. Costae
strong, broad, crowded, commonly angular, less com-
monly rounded in section, separated by angular
troughs of width equal to costae; commonly arising 5
to 7 mm from ventral beak, numbering three to five on
dorsal fold, three to five on each flank; costae on
flanks less pronounced than mesially. Concentric or-
nament absent; growth lines faint, rare.

Ventral valve low, but strongly convex through sul-
cus, slightly convex on flanks; beak sharp, attenuate,
commonly parallel to hingeline; lateral pseudointer-
areas narrow, partly covered by overlap of dorsal
valve. Delthyrium narrow, open, basically closed by
disjunct trapezoidal deltidial plates; pedicle foramen
elongate, oval.

Dorsal valve moderately to strongly convex trans-
versely and longitudinally, more so in mature individ-
uals; non-costate umbo may be slightly indented.

Ventral interior having sides of delthyrium widely
diverging anterior to deltidial plates; teeth elongate,
supported by strong vertical dental plates reaching
floor of valve. Muscle field poorly impressed.

Dorsal interior having undivided but anteriorly
notched triangular hinge plate, bounded laterally by
deep, anteriorly more massive sockets; apparent fal-
cifer crura projecting anteriorly; extremities not ob-
served. Low median ridge on valve floor separating
elongate oval, apparently striate adductor scars.

Measurements (in mm).—

Costal
Origin
Maxi- Number Number Distance
Dorsal Maxi- mum of of from
Valve mum Thick- Costae Ventral Ventral
Length Length Width ness on Fold Costae Beak
Loca.ity 8
USNM 221282 11.3 9.6 10.7 Weil 3 11 6,
USNM 221283 12.1 10.7 12.5 10.6 11 Ss
Locatity 10
USNM 221280 i13}.5}. 11.9, 16.0, 12.4... 3 12 Te
USNM 221281 14.5, 12518 16.2, 12 3 12 Te
Locatity 11
USNM 221275 8.5 _— 8.6 — — 14 6
USNM 221276 8.9, 8.0 8.6 5.0 3 11 6
USNM 221277 9.8 8.6 9.2 3.8 3 11 6
USNM 221278 12.4 10.7 11.1 8.7 5 13 7
USNM 221279 16.1, 14.1, 1S25¢ 12.4, 3 14 Th

Occurrence.—Pontisia stehlii has been recovered in
the West Texas region from rocks ranging in age from
Leonardian (Cathedral Mountain and Road Canyon
Formations) to Early Guadalupian (middle Word For-
mation). In the Palmarito Formation it has been re-
covered from localities 8, 10 and 11. It is not a com-
mon faunal element at any of these localities. A
Leonardian to Early Guadalupian age is consistent
with other biostratigraphic indicators.

Diagnosis.—Large Pontisia having deep dorsal
valve and closely crowded angular costae, but smooth
beaks and umbonal areas.

Types.—Figured Specimens: USNM 221277-221280,
USNM 221283, USNM 221284; Measured Specimens:
USNM 221275221283.

Comparison.—Mature individuals of P. franklinen-
sis Cooper and Grant (1976a), P. nanas (Stehli, 1954),
P. parva Cooper and Grant (1976a) and P. wolfcam-
pensis Cooper and Grant (1976a) are markedly smaller
than similar growth stages in P. stehlii. The low dorsal
valve of P. kingi Cooper and Grant (1976a) easily dis-
tinguishes that species from P. stehlii, and the larger,
coarser and sparser costae of P. costata Cooper and
Grant (1976a), P. magnicostata Cooper and Grant
(1976a) and P. truncata Cooper and Grant (1976a) ef-
fectively distinguish those species. The costae of P.
longicosta (Stehli, 1954) arise much closer to the beaks
than do those of P. stehlii. P. ventricola Cooper and
Grant (1976a) presents a much smoother exterior than
does P. stehlii. P. robusta Cooper and Grant (1976a)
is less globose and more transverse than most speci-
mens of P. stehlii.

P. stehlii is similar to Pontisia sp. Stehli and Grant
(1970) from the Chochal Limestone (Leonardian) of
Guatemala, but differs from that poorly known species
in its more globose form, broader and higher fold and
sulcus, and its somewhat more pronounced ornament.

P. stehlii may easily be differentiated from a small-
er, paucicostate, less globose Pontisia from the Co-
pacabana Formation (Wolfcampian) of the Lake Titi-
caca region, Peru and Bolivia.

Discussion.—It may be considered by some unwar-
ranted to assign the same species name to forms from
such presently distant areas as Venezuela and West
Texas. In this case however, the morphology of indi-

BULLETIN 313

viduals and the variation in samples of populations are
so strikingly similar that such a conclusion is inescap-
able.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
8 6 — — fine silicification
10 3} 1 — fine silicification
11 11 5) 6 fine silicification

Pontisia cf. P. stehlii tumidosa
Cooper and Grant
Plate 7, figures 24-36

cf. Pontisia stehlii tumidosa Cooper and Grant, 1976a, p. 2028, pl.
510, figs. 56-62; pl. 535, figs. 52-66.

Description.—Small- to medium-sized, average for —

genus, subtrigonal to subpentagonal in outline, dorsal
valve deeper than ventral. Sides rounded, greatest
width at or anterior to midvalve; anterior margin mod-
erately rounded to subtruncate; anterior commissure
uniplicate. Beak short, sharply angular, having elon-

gate pedicle foramen and elevated, short, disjunct del- —

tidial plates. Surface variably costate, having from

three to six, commonly three, rounded to subangular —

costae on the dorsal fold, and four on each flank. In-
tercostal furrows narrower than costae.

Ventral valve moderately convex in lateral profile;
broadly and gently convex in anterior profile. Sulcus
originating near midvalve; broad, shallow, poorly to
moderately defined. Tongue moderately strongly ge-
niculated, convex in lateral aspect. Costae commonly
arising about 4 mm anterior to ventral beak.

Dorsal valve moderately convex in lateral view, but
strongly domed in anterior view, having nearly vertical
flanks. Umbonal region gently convex; fold originating
near midvalve, moderately wide, only slightly elevated
above flanks through entire length, flat-crested in ma-
ture specimens.

Interior as for Pontisia stehlii.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 87

Measurements (in mm).—

Costal
Origin
Maxi- Number Number Distance
Dorsal Maxi mum of of from
Valve mum Thick- Costae Ventral Ventral
Length Length Width ness of Fold Costae Beak
LocaLity 3
USNM 221285 4.9 4.4 4.2 322 3 9. 4.
USNM 221286 6.0 aio) Set 4.1 4 13, 4.
USNM 221287 6.7 oul TP 55) 3 13 4
USNM 221288 7.0 6.5 RES 4.6 3 13 4.
USNM 221289 Wes} 6.4 7.4 5.0 4 15 4
USNM 221290 7.3 6.5 Goll Sul 3 14 4
USNM 221291 75 6.5 7.7 5.9 4 13 4
USNM 221292 7.6 6.4 7.9 5.8 3 13 4
USNM 221293 7.6 7.0 7.6 6.0 3 13 4
USNM 221294 8.1, 7.4y 8.5. 6.8. 4 rie 4
USNM 221295 8.6 cS) 8.2 eh 4 14 4
USNM 221296 8.6, 7.6 9.6 6.8 5 16 3\,
USNM 221297 10.5,. 9.3. 13.3 9.3 6 14 4.
Occurrence.—Pontisia stehlii tumidosa occurs in Material.—
the Cathedral Mountain and Road Canyon Formations a
si s) rticu-
(Leonardian) of West Texas. In the Palmarito For- Eee es eA wena Type of
mation the form tentatively referred to this subspecies ity Wakes Walkee Wakes Procemation
has been recovered only from locality 3, where it is 5 7 " 7" AGAR

common. A Leonardian age for that assemblage is not
inconsistent with other biostratigraphic indicators.

Diagnosis.—Rotund and bulbous Pontisia having
costae extended to but not onto the beaks.

Types.—Figured Specimens: USNM 221285, USNM
221286, USNM 221289, USNM 221292, USNM
221295, USNM 221298; Measured Specimens: USNM
221285—221297.

Comparison.—Pontisia stehlii tumidosa is distin-
guished from other West Texas Pontisia species by its
more dense costation and more globular profile. It is
distinguished from P. stehlii stehlii Cooper and Grant
(1969) by its smaller average size, lower fold, shallow-
er sulcus, more convex ventral valve and more exten-
sive costation. The Venezuelan form here referred
tentatively to the subspecies differs from that West
Texas form in having apparent disjunct rather than
conjunct deltidial plates, and by having a slightly more
transverse outline, although this latter feature may in
part be due to crushing.

RHYNCHONELLACEA family uncertain
Plate 7, figures 49-55

Discussion.—A number of small shells, trigonal in
outline and bearing characteristic rhynchonellacean
costation were recovered from Palmarito locality 6,
blocks B & C, and locality 10. The latter differ from
Pontisia stehlii Cooper and Grant (1969), in their
smaller size, more extensive, finer costation, and less
globose profile, and from Pontisia cf. P. stehlii tumi-
dosa Cooper and Grant (1976a) in their more elongate,
more distinctly trigonal outline, and their less globose
profile. Their profile suggests they may be juveniles.
No apical interiors were sufficiently well preserved to
permit determination of familial affinities. The material

88 BULLETIN 313

from locality 6 is so fragmentary (a single ventral valve
is the only unbroken specimen) that taxonomic con-
formity with those from locality 10 cannot be assured.

Types.—Figured Specimens: USNM 221300-221302;
Measured Specimens: USNM 221299-221303.
Measurements (in mm)—

Costal
Origin
Maxi- Bs Distance
Dorsal Maxi mum Number of Costae from
Valve mum Thick- Ventral
Length Length Width ness Ventral On Fold Beak
Loca.ity 10
USNM 221299 5.98 5.4 5) 7/ 3.1 16 4 4
USNM 221300 6.0 5.0 5.0 Soll 14, 3 4.
USNM 221301 6.6 5.8 7.0 4.5 16 4 4.
USNM 221302 6.9 5.9 se) 3.6 16 4 4
USNM 221303 6.9 6.2 6.1 4.0 14 3 4
Material.— Hustedia hyporhachis new species
ee Plate 8, figures 1-18
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation Etymology of Name.—Gr. hypo = smaller; Gr.
6 (block B) = 2 2 fine silicification rhachis = backbone, midrib.
6 (block C) = = 4 fine silicification Description.—Small to medium-sized, average for
10 5 _ _ fine silicification

Order SPIRIFERIDA Waagen, 1883
Suborder RETZIIDINA
Boucot, Johnson and Staton, 1964
Superfamily RETZIACEA Waagen, 1883
Family RETZIIDAE Waagen, 1883

Genus HUSTEDIA Hall and Clarke, 1893

Types Species.—Terebratula mormoni Marcou,
1858, p. 51, pl. 6, figs. 1la—c.

Diagnosis.—

Small, strongly costate ... [Retziidae] with a rostrate pedicle
beak and a flat symphytium. (Stehli, 1954, p. 350)

Occurrence.—Hustedia is known from rocks vary-
ing in age from Mississippian through Permian, in Eu-
rope, Asia, and the Western Hemisphere. In the Perm-
ian its distribution appears to have been tropical to
subtropical: it does not appear in truly Boreal assem-
blages. It is probably the most common brachiopod in
the Palmarito fauna, occurring at localities 1, 3, 6, 8,
10, 11 and 13, and being the dominant faunal element
in assemblage 10.

Comparison.—The family Retziidae is rather poorly
represented in the Upper Paleozoic, only two of nine
genera assigned to it in the Treatise (Williams et al.,
1965) falling within that time range. Only Hustedia
and Thedusia Cooper and Grant (1976b), represent the
family in the Permian. Thedusia is easily distinguished
from Hustedia by its generally smaller size, elongate
beak, bisulcate valves and emarginated anterior.

genus, strongly biconvex; outline elongate suboval,

normally widest at or slightly anterior to midlength; |

commissure serrate, anteriorly bearing low fold and

sulcus; costae commonly rounded to square-topped, —

from 11 to 16, commonly 13 on dorsal valve; median
costa of dorsal valve depressed near beak in juveniles,
anteriorly somewhat broader, more flat-topped than
lateral costae; median trough of ventral valve slightly
wider than lateral troughs, most mature specimens
bearing a very weak median ridge anteriorly; fold and
sulcus development encompassing mesial three to four
costae; growth lines fine, rarely visible, growth lami-
nae weak, normally observed only near anterior mar-
gins.

Ventral valve deepest near midvalve, anterior to
dorsal umbo; beak somewhat long, blunt, suberect to’
erect; foramen round, of normal size, permesothyri-
did; symphytium longitudinally concave.

Dorsal valve deepest just anterior to umbo, com-.
monly posterior to greatest width of shell, commonly

slightly less convex than ventral valve; beak blunt, |

curving only slightly posterior to hinge.
Ventral interior having blunt, transverse teeth; ped-|

icle collar rarely preserved; crests of internal costae’

flat to slightly concave, flanks of internal costae of
anterior third to half of valve bearing one to several.
short lirae that may crenulate anterior margin. I

Dorsal interior having moderately deep sockets;
hinge plate short, only slightly recurved, projecting,
anteroventrally, median portion near base extended as’
short curved ligulate process projecting ao
)
|
}

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 89

trally; median septum very short, low, thin, apically side, axis of spire at right angles to shell length across
confined, extending at most 1-2 mm along valve floor; widest part; costae and intercostal lirae as in ventral
crura short, projecting ventrally; mesial portions of valve.
spiralium not preserved intact, up to ten loops on each Measurements (in mm).—
Dorsal Number of
Total Valve Total Hinge Thick- Dorsal
Length Length Width Width ness Costae

Loca.ity 10

USNM 221304 3.6 7x) 2-9 1.0 1.7 13
USNM 221305 3.9 3.0 3. 1.4 2.2 15
USNM 221306 5.0 4.0 4.0 1.5 3.2 15
USNM 221307 5.1 4.0 4.4 1.7 3.0 13
USNM 221308 523 4.2 4.2 1.6 2.8 13
USNM 221309 5.4 4.2 4.7 1.7 3.4 13
USNM 221310 5.5 4.4 4.8 1.8 3.2 13
USNM 221311 Sh// 4.7 3:3 Noa 3.6 13
USNM 221312 6.3, D2 4.8 1.5 3.8 13
USNM 221313 6.7 5.0 5.0 1.8 3.7 13
USNM 221314 6.8 6.0 5.3 2.2 4.0 15
USNM 221315 7.0 6.0 =) 2.0 4.4 15
USNM 221316 7.0 5.9 6.2 2.0 4.1 15
USNM 221317 7.1 5.8 SD) 1.8 4.2 13
USNM 221318 7.1 529) 5.5 il57/ 4.5 13
USNM 221319 73 6.0 6.3 D5) 4.8 13
USNM 221320 7.4 6.3 6.3 1E7 4.5 13
USNM 221321 7.4 6.5 6.3 1.8 4.6 13
USNM 221322 165) 6.0 4.5 1.8 4.0 13
USNM 221323 7.5 6.0 6.6 ep) S74 13
USNM 221324 We) 6.4 5.6 1.8 4.2 13
USNM 221325 7.6 6.1 6.8 2.0 4.8 11
USNM 221326 7.8 6.1 6.2 2.1 4.9 13
USNM 221327 8.3 6.6 7.1 2.4 5.0 13
USNM 221328 8.5. 7.0 6.4 17 4.8 13
USNM 221329 8.5 7.0 Uc3} 2.4 Sell 15
USNM 221330 8.7 6.8 Tal 2.2 5.5 13
USNM 221331 8.8 7.0 7.1 2.4 5.7 13
USNM 221332 8.8 7.5 Hel DED She 13
USNM 221333 9.0 Ue) 7.8 2.0 5.5 13
USNM 221334 O28 Tede 7.8 Ze 5.7 13
USNM 221335 Oy 7.8 7.8 2.2 5:5 13
USNM 221336 9.3 7.6 Wee? 2.2 Shp) 13
USNM 221337 9.5 Ws) 8.2 es) 6.0 15
USNM 221338 95 7.8 Vell 1.8 5.8 13
USNM 221339 9.6 8.0 8.2 2.2 Sell 13
USNM 221340 9.7 7.8 Hell 2.0. 5.8 13
USNM 221341 OF 8.0 8.3 2.8 6.4 15
USNM 221342 OF7. 8.1 8.4 3.0 6.3 13
USNM 221343 Oi 8.3 7.8 2.0 5.8 13
USNM 221344 9.8 7.8 8.2 23 6.0 13
USNM 221345 10.0 8.0 935 2.2 6.2 13
USNM 221346 10.0 8.2 UP 2.3 6.5 13
USNM 221347 10.3 8.8 9.7 3.0 6.9 15
USNM 221348 10.5 8.7 8.7 Dll 7.1 13
USNM 221349 10.5 8.7 91 2.9 S)s1/ 13
USNM 221350 11.0 OLS) 9.1 2.6 Ze 13
USNM 221351 11.3 9.6 9.1 3:2 6.4 13
USNM 221352 11.3 9.8 TES) 2.8 7.8 13
USNM 221353 11.3 9.8 O51 3.2 7.5 13
USNM 221354 11.4 9.9 10.0 3.1 7.6 13
USNM 221355 11.7 10.1 8.9 Sill ee) 13
USNM 221356 12.0 10.3 9°5 3.0 7.8 13

90 BULLETIN 313

Dorsal Number of
Total Valve Total Hinge Thick- Dorsal
Length Length Width Width ness Costae

USNM 221357 12.1 9.8 9.1 3.4 Ve? iN7/
USNM 221358 1252 10.3 9.6 3.0 7.8 15
USNM 221359 12.4 10.5 9.8 3.4 8.0 13
USNM 221360 25) 10.5 10.1 3303) 8.1 13
USNM 221361 17225) 10.8 10.6 BE 7.9 13
USNM 221362 12.7 11.0 10.5 3:3 8.8 13
USNM 221363 12.9 10.8 11.0 3.2 9.2 13
USNM 221364 12.9 11.1 10.6 3.5 8.1 13
USNM 221365 13.1 11.1 10.6 3.3 8.5 13
USNM 221366 [372 11.2 10.1 8)55) 8.6 13
USNM 221367 13.3 11.1 10.8 3.4 8.4 13
USNM 221368 13.3 11.6 11.2 353 8.9 13
USNM 221369 13.3 11.8 i283} 2.8 8.9 11
USNM 221370 13.4 11.3 10.8 3.5 9.8 13
USNM 221371 13.5 11.7 iVi1.3} 3.7) 8.6 13
USNM 221372 13.5 11.8 11.7 3.4 9.2 13
USNM 221373 13.5 11.4 10.9 3.6 8.4 13
USNM 221374 13.6 11.7 11.5 3.8 9.6 16
USNM 221375 13.8 11.7 11.0 3.6 8.2 14
USNM 221376 13.8 11.8 10.5 aml 10.0 13
USNM 221377 13.8 12.0 11.5 3.4 10.0 13
USNM 221378 14.0 12.0 12.1 3\7/ 9.8 15
USNM 221379 14.2 11.9 11.8 35) 07 13
USNM 221380 14.2 12.1 12.6 317/ 9.8 13
USNM 221381 14.3 12a 10.8 3.0 9.0 13
USNM 221382 14.3 12.2 10.6 32 10.4 15
USNM 221383 14.4 12.1 11.1 33,5) 8.4 13
USNM 221384 14.6 12.6 Lilet 3.2 93) 13
USNM 221385 14.6 7) 11.2 3.4 9.8 13
USNM 221386 14.8 2-7) Mb, 7/ 3.6 10.4 15S
USNM 221387 15.0 12.7 11.7 3.6 10.1 15
USNM 221388 15.0 12.7 13.4 4.5 11.0 13
USNM 221389 15.0 12.9 12.4 4.1 10.6 15
USNM 221390 15.0 13.0 12.9 3.8 9.6 13
USNM 221391 15.0 13.1 10.8 2.6 11.2 13
USNM 221392 152 1-5) 11.5 4.3 10.5 13
USNM 221393 1S 13.0 12.2 3.4 10.2 13
USNM 221394 15.2 13.2 12.3 3).5) 10.7 13
USNM 221395 15.3 12.9 13.2 3.8 12.1 13
USNM 221396 15.5 113}33 12.8 4.4 11.1 15
USNM 221397 15.6 135 ES 4.0 123 13
USNM 221398 15.6 13.5 rt 7/ 2.6 10.3 13
USNM 221399 16.0 13.4 22 4.1 10.7 15
USNM 221400 16.1 13.7 11.9 3}5) 12.1 13
USNM 221401 16.3 14.0 12.8 3.6 11.0 13
(holotype)

USNM 221402 16.4 13.7 3.3 4.3 72

USNM 221403 16.7 14.7 12 4.1 0 3

Occurrence.—Hustedia hyporhachis has been re-
covered from localities 3, 10, 11 and 13 in the Pal-
marito Formation. Juvenile specimens questionably
referable to the species, resembling juveniles from lo-
calities 10 and 13, were recovered from locality 6,
blocks A and C. H. hyporhachis is uncommon in the
assemblages at localities 3, 6 and 11, and common to

abundant in those of localities 10 and 13. At locality
10 it dominates the fauna.

The most closely related West Texas form, H. con-

suta Cooper and Grant (1976b) has been recovered !

from the upper portion of the Cathedral Mountain For-

mation, and from the Road Canyon and Cibolo For- |

mations, all of Leonardian age. Such an age assign-

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 9]

ment is not inconsistent with other biostratigraphic
indicators in the Palmarito faunal assemblages.
Diagnosis.—Average-sized, strongly convex Hus-
tedia, having low, rounded costae and a thin median
ridge in the median trough of the ventral exterior.
Types.—Holotype: USNM 221401; Figured Speci-
mens: USNM 221308, USNM 221324, USNM 221335,
USNM 221339, USNM 221352, USNM 221354,
USNM 221358, USNM 221370, USNM 221386,
USNM 221399, USNM 221401, USNM 221404-
221406; Measured Specimens: USNM 221304-221403.
Comparison.—H. hyporhachis may be distin-
guished from H. crepax Cooper and Grant (1976b),
H. culcitula Cooper and Grant (1976b) and H. trita
Cooper and Grant (1976b) by the absence of striae on
the internal costal flanks in those forms. The smaller
size of mature individuals of H. bipartita Girty (1909,
H. catella Cooper and Grant (1976b), H. hapala Coo-
per and Grant (1976b), H. inconspicua Cooper and
Grant (1976b), H. lusca Cooper and Grant (1976b), H.
narinosa Cooper and Grant (1976b), and H. trisecta
Cooper and Grant (1976b), and the larger size of ma-
ture individuals of H. citeria Cooper and Grant
(1976b) and H. rupinata Cooper and Grant (1976b)
effectively distinguish those species from H. hypo-
rhachis. The smaller average number of costae in H.
cepacea Cooper and Grant (1976b), H. citeria, H.
compressa Cooper and Grant (1976b), H. consuta
Cooper and Grant (1976b), H. decollatensis Cooper
and Grant (1976b), H. opsia Cooper and Grant
(1976b), H. samiata Cooper and Grant (1976b), H.
spicata Cooper and Grant (1976b), and H. tomea Coo-
per and Grant (1976b) and greater average number of
costae of H. cuneata Cooper and Grant (1976b), H.
huecoensis R. E. King (1931) and H. stataria Cooper
and Grant (1976b) distinguish those forms from H.
hyporhachis. The lamellose anterior and short median
costa of H. demissa Cooper and Grant (1976b) effec-
tively distinguishes that form, while the thickened
shell of H. connorsi Cooper and Grant (1976b) distin-
guishes that form. The presence of obvious growth
lines on H. ampullacea Cooper and Grant (1976b), H.
glomerosa Cooper and Grant (1976b), H. hessensis R.
E. King (1931), H. pugilla Cooper and Grant (1976b)
and H. sculptilis Cooper and Grant (1976b) distin-
guishes those species from H. hyporhachis. H. hy-
porhachis differs from all West Texas species but H.
consuta in bearing the thin median lira in the ventral
median exterior trough, and differs from that species
in its lower, more rounded, and somewhat more nu-
merous costae.
H. hyporhachis generally resembles H. grandicosta
(Davidson, 1862) from the Upper Productus Lime-

stone of the Salt Range, but differs, bearing a mesial
ridge in the median ventral exterior trough. It is similar
to H. sicuaniensis Chronic (1949) from the Copaca-
bana Formation of Peru, which appears to have a weak
median ventral mesial lira (Newell, Chronic ef al.,
1953, pl. 17, fig. 7b), but differs from that species in
its posteriorly indented dorsal valve, larger mature in-
dividuals, and the presence of striations on the flanks
of the internal costae, which H. sicuaniensis does not
appear to have (Cooper and Grant, 1976b, p. 2763).

Discussion.—The taxonomically significant features
of the species of Hustedia are commonly quite subtle.
Assignment to species is a difficult task requiring ex-
amination of large population samples, in order to de-
termine the size, form and characteristics of juvenile
and mature individuals, and the ranges of variation of
taxonomically significant characters at various growth
stages and throughout ontogeny. Without such a large
suite, proper placement of isolated specimens within
an ontogenetic framework, and consequently specific
identification, can be seriously hampered. In H. hy-
porhachis, three such characters (length, width, thick-
ness) are related in a systematic manner. Text-figure
11 shows the relationships of these parameters for two
population samples of H. hyporhachis (locs. 10 and
13) and a single sample of H. consuta. It may easily
be seen that there is a linear relationship between
length and width during ontogeny, while the relation-
ship between length and thickness is non-allometric,
thickness increasing little during early as compared to
later stages of ontogeny. The latter relation is subtle,
but can be seen in all three plots, and is a common
ontogenetic strategy in many groups of brachiopods,
indicating that there is some threshold size which must
be attained before substantial increase in the internal
volume of the shell can be initiated.

The difference in dispersion of the plots from local-
ities 10 and 13 may possibly be explained by exami-
nation of the overall character of those assemblages.
At locality 10, H. hyporhachis is the dominant bra-
chiopod present: large numbers of individuals com-
peted for the available living space, and were often
closely crowded together. Such close proximity may
influence the shape of mature shells by randomly lim-
iting directional growth. At locality 13 however, no
such crowding appears to have occurred, although the
assemblage is unquestionably autochthonous. Shells
in such an uncrowded environment would be free to
follow an “‘ideal’’ growth plan, and there would be
less deviation from their standard mode of ontogenetic
development.

The appearance of internal striations on the inter-
costal flanks may be of considerable stratigraphic sig-

92 BULLETIN 313

Text-figure 11.—Scattergrams of dimensions of two population
samples of Hustedia hyporhachis n. sp. from Venezuela and one
population sample of Hustedia consuta Cooper and Grant (1976b)
from West Texas. In all diagrams, the upper vertical axis represents
maximum width; the middle, horizontal axis represents shell length;
and the lower vertical axis represents the maximum thickness. All
measurements are in mm. The dashed lines indicate equidimension-
ality.

nificance. Stehli (1954, p. 351) hypothesized that they
might represent an interlocking straining device, op-
erational at the anterior margin. Cooper and Grant
(1976b, p. 2761), following an informal suggestion by
Stehli, demonstrated that such valve margin crenula-
tions do not interlock in articulated silicified speci-
mens, and in many cases leave large gaps along the
commissure which would not serve well as incurrent
strainers. They suggest that these internal ridges may
have served as seats for attachment of marginal setae
which appear to have been present in many groups of
brachiopods.

These striae appear to have been a rather late de-
velopment in the Retziidae, appearing only in the
Permian forms, and were not well-expressed until the
Leonardian. Those of H. hyporhachis appear to arise
at about midvalve in most cases, and to continue dis-
tinctly to the anterior margin, indicating that they
arose early in ontogeny. This morphological-strati-
graphic relationship tends to support the Leonardian
age indicated by other Palmarito biostratigraphic in-
dicators.

Material.—
Articu-
lated Dorsal Ventral Type of

Locality Valves Valves Valves Preservation

3 19 a 1 fine silicification

6 (block A) 11 2 — fine silicification

6 (block B) 2 2 _ fine silicification

6 (block C) 14 I 6 fine silicification

10 297 33 38 fine silicification

11 30 13 11 medium-grained
silicification

13 81 8 7 fine silicification

Hustedia sp.
Plate 7, figures 37, 38

Discussion.—A single poorly preserved specimen
referable to the genus Hustedia was recovered from
each of localities 1 and 8. No internal details can be
seen, and the surface is insufficiently preserved to al-
low even a count of number of costae. The specimens
are, however, of the same general size and shape as

A. Plot for Hustedia hyporhachis from locality 10, Palmarito
Formation (100 specimens).

mature individuals of Hustedia hyporhachis n. sp.,
although they cannot confidently be assigned to that
or any other species of the genus.

Types.—Figured Specimens: USNM 221407, USNM
221408.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
1 ] oo — calcite permineralization
8 1 — — coarse silicification

Suborder ATHYRIDIDINA
Boucot, Johnson and Staton, 1964
Superfamily ATHYRIDACEA McCoy, 1844

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 93

B. Plot for Hustedia hyporhachis from locality 13, Palmarito
Formations (100 specimens).

Family ATHYRIDIDAE McCoy, 1844
Subfamily ATHYRIDINAE McCoy, 1844

Genus CLEIOTHYRIDINA Buckman, 1906

Type Species.—Spirifer deroysii Leveille, 1835, p.
39 = Athyris roysii Davidson, 1860, p. 84, pl. 18, fig.
8 (by original designation of Buckman, 1906, p. 324).

Diagnosis.—Athyridinae having concentric lamellae
that bear short spines, ventral beak without interarea,
subcircular pedicle foramen that penetrates the apex
of the beak, small dental plates in the ventral interior
and an apically perforate hinge plate in the dorsal in-
terior.

Occurrence.—Cleiothyridina occurs in rocks rang-
ing in age from Late Devonian through the Permian,

C. Plot for Hustedia consuta Cooper and Grant (1976b), locality
707e, Road Canyon Formation, West Texas (42 specimens:
larger dot represents the dimensions of the holotype).

and its distribution is cosmopolitan. In the Permian it
occurs in both Austral and Boreal regions, and is com-
mon in Europe and Asia. It is a rare element in West-
ern Hemisphere Permian faunas, where the species
are generally small and easily overlooked. Two frag-
mentary specimens referable to the genus have been
recovered from locality 3 in the Palmarito Formation.
Comparison.—The Palmarito Formation forms of
Cleiothyridina may easily be distinguished from Com-
posita Brown (1849), the only other co-occurring
athyridine genus, by its characteristic broad lamellar
extensions, arising at the concentric growth lines, and
extending anteriorly as fine solid spines.
Discussion.—Cleiothyridina demonstrates one of
the difficulties inherent in recognizing many of the cos-
mopolitan forms in their Tethyan realm occurrences:

94 BULLETIN 313

genera which are relatively abundant and possess
shells of moderate size in Boreal and Temperate
realms, appear to exist at a competitive disadvantage
at lower latitudes, where they are rare, small and
patchily distributed.

Cleiothyridina cf. C. nana Cooper and Grant
Plate 8, figures 19-25

cf. Cleiothyridina nana Cooper and Grant, 1976a, p. 2136, pl. 650,
figs. 36-49, 84-99.

Description.—Small, small for genus, suboval to
subpentagonal in outline, moderately globose in lateral
aspect, biconvex; greatest width at or anterior to mid-
length, commissure weakly uniplicate; fold low and
rounded, sulcus shallow, limited to anterior portion of
shell; concentric lamellae closely spaced, spinose,
spines better preserved nearer margins, short, closely
spaced; posteriorly bearing fewer and lower spines
and numerous spine bases; growth laminae few and
weak.

Ventral valve moderately convex; beak thick, near-
ly straight; foramen small, round, poorly preserved,
piercing beak at apex; dorsal valve somewhat more
convex, especially posteriorly, bearing small spines as
on ventral valve.

Interiors unknown.

Measurements (in mm).—

Maxi- Height
Dorsal = Maxi- mum of Fold
Valve mum Thick- at Com-
Length Length Width ness — missure
Loca.ity 3
USNM 221409 7.0 6.0 6.5. 5.0 125

Occurrence.—Cleiothyridina nana has previously
been recovered only from the Road Canyon Formation
(Leonardian of West Texas), where it is rare. In the
Palmarito Formation it is also rare. Only a single ju-
venile and a single adult specimen were recovered
from locality 3. A Late Leonardian age for that locality
in the Palmarito is not inconsistent with other bio-
stratigraphic indicators.

Diagnosis.—Very small Cleiothyridina with slightly
folded anterior commissure.

Types.—Figured Specimens: USNM 221409-221410;
Measured Specimen: USNM 221409.

Comparison.—C. nana is effectively distinguished
from C. ciriacksi Cooper and Grant (1976a), C. rara
Cooper and Grant (1976a), C. rectimarginata Cooper
and Grant (1976a) and several undescribed species
from the West Texas region by the slight uniplication
of its anterior commissure. Its commissure is, how-

ever, less strongly uniplicate than that of another West
Texas species, C. pilularis Cooper and Grant (1976a).
C. mulsa Cooper and Grant (1976a) is very weakly
uniplicate, and has vestigial dental plates, compared
to the robustness of those features in C. nana. The
Bolivian species C. intonsa Chronic (1949) is recti-
marginate.

Discussion.—Cleiothyridina cf. C. nana is rare in
the Palmarito Formation. The small size of this form
agrees well with other Western Hemisphere Tethyan
species of the genus. Its rarity in apparently autoch-
thonous collections of silicified material may indicate
that its life distribution was extremely discontinuous,
rather than that the sampling was poor.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
3 2 _ — fine silicification

Genus COMPOSITA Brown, 1849

Type Species.—Spirifer ambiguus Sowerby, 1823,
p. 105, Tab. 376, 4 figs. (by original designation of ©
Brown, 1849, p. 131).

Diagnosis.—Biconvex, streamlined narrow-hinged
Athyridinae lacking interarea or beak ridges, having
uniplicate commissure and proportionately large oval,
epithyridid or permesothyridid pedicle foramen.

Occurrence.—Composita has been reported from
rocks of Devonian through Permian age. In the Perm-
ian it appears to have had a world-wide Tethyan dis-
tribution. Although it occurs sparingly in intermediate
(“‘temperate’’) paleoclimatic zones, it has never been
reported from Boreal assemblages. In the Western
Hemisphere it is known from southern and central
North America, northern Central America and north- —
ern and central South America.

Comparison.—Its longer, more erect beak, larger
pedicle foramen, generally more elongate outline and
lack of surface spines distinguish Composita from the
other co-occurring athyridine genus Cleiothyridina
Buckman (1906). The lack of beak ridges or deltidial |
plates, and the type and position of the pedicle fora- —
men distinguish Composita from Dielasma W. King
(1859). Neophricadothyris Likharev (1934) or Marti-
nia McCoy (1844) have the same sort of outline, but ©
may be distinguished by their trigonal delthyria and |
unperforated beak apices.

Discussion.—Composita, originally separated from |
the genus Spirifer Sowerby (1816), is still of relatively |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 95

hoary antiquity. Although it now houses probably less
than half the species originally assigned to it, due to
refinement of the genus over the last hundred or more
years, the number of species within the genus taxes
the credulity of the average investigator. Various in-
vestigators (e.g., Grinnell and Andrews, 1964; Lutz-
Garihan, 1974) have demonstrated that a continuum
of intergrading forms exists between several of the
better-known species of Composita in North America.
The artificiality of paleospecies assignment is rarely
better exhibited than in Composita.

The brachiopod fauna of the Palmarito Formation
appears to show greatest overall similarity to forms
from the Permian basins of West Texas: therefore it
is among these well-studied and thoroughly investi-
gated faunas that similar species of Composita are
chiefly sought.

Composita cf. C. pilula Cooper and Grant
Plate 8, figures 26-38

cf. Composita pilula Cooper and Grant, 1976a, p. 2159, pl. 657,
figs. 1-39.

Description.—Small, small for genus, subtrigonal,
subovate or subpentagonal in outline, commonly
somewhat elongate, widest anterior to midlength; an-
terior commissure weakly parasulcate; fold standing
only slightly higher than flanks anteriorly, sulcus ex-
pressed anteriorly only; growth laminae weak, widely
spaced over most of shell; stronger, more crowded
nearer margins; latest growth increments of largest
specimens imbricate, forming somewhat inset, corru-
gate face oriented normal to plane of commissure.

Ventral valve strongly convex, radius of curvature
smallest posteriorly; beak short, thick, suberect or
erect; foramen small, periphery narrowly incomplete;
edge of valve flanged or bearing shallow groove in
most mature specimens.

Dorsal valve less strongly convex, greatest height
at or slightly anterior to umbo, but posterior to mid-
valve; valve margins fitting flange or groove of oppo-
site valve.

Ventral interior having slender, sharp, posterodor-
sally recurved pair of hinge teeth; dental plates thin,
subparallel, free of apical walls anteriorly; muscle area
shallowly impressed, pattern normal for genus.

Dorsal interior having small hinge plate, with deep
median notch in many specimens; cardinal process
bilobate, lobes bearing small muscle attachment mark
on anterodorsal faces; adductor muscle attachment
area elongate, narrow, having low median dividing
ridge posteriorly; crura, descending lamellae and spi-
ralia not seen.

Measurements (in mm).—

Dorsal Maximum
Total Valve Maximum _ Thick-
Length Length Width ness
LocaLirty 3
USNM 221411 17.7. 1523 — il.
LOCALITY 4
USNM 221412 11.8 10.2 10.5 8.3
USNM 221413 13.0, 11.5, 10.0, 8.7.
LOCALITY 7
USNM 221414 15.0 12.7 12.5 10.9
USNM 221415 7? 14.8 14.3. 11.8,
USNM 221416 17.5 15.0 16.9 12.0
USNM 221417 18.4 Se2= 16.1 13.6
USNM 221418 21.8 18.5, 18.6 14.6,
USNM 221419 22 18.8, 19.3 16.1
LocaLiTy 8
USNM 221420 5.4 4.6 522 3.0
USNM 221421 6.7 6.2 6.1 4.4
USNM 221422 7.8 6.9 7.1 5.0
USNM 221423 8.5, Use) 7.4 5153}
USNM 221424 10.0. 9.056 8.1, 6.5),
USNM 221425 11.9 10.5 10.0 7.9
USNM 221426 12.44. 11.7 10.4 7.6
USNM 221427 12.5. Nilez/ 10.1 8.2
USNM 221428 12.9 11.1 11.9 8.4
USNM 221429 12.9 11.2 10.6 8.2
USNM 221430 13.1 11.4 11.6 8.1
USNM 221431 13.3 11.3 10.8 8.6
USNM 221432 13.3 11.3 11.5 9.0
USNM 221433 13.5 11.9 12.4 8.4
USNM 221434 14.3). 1Sailre 11.5 G3}
USNM 221435 15.8 13.6 13.0 9.7
Locatity 11
USNM 221436 16.2 13.5 13.8 10.9).
USNM 221437 17.8 15.2 17. 1p. 12.2
Loca.ity 13
USNM 221438 — = sP255) 9.5
USNM 221439 14.9 13.0 11.4 9.7

Occurrence.—Composita pilula, in the West Texas
region where it was first described, has been recovered
only from the Road Canyon Formation (Leonardian).
In the Palmarito Formation it is one of the more ubi-
quitous articulate brachiopods, occurring sparingly in
assemblages 1, 3, 4, 7, 10, 11 and 13 and abundantly
in assemblage 8. A Late Leonardian age for all of these
assemblages is not inconsistent with other biostrati-
graphic indicators.

Diagnosis.—Shell small, outline elongate, beak
short, growth laminae strong near margins, margins
commonly flanged or grooved, fold and sulcus very
weak, commissure weakly parasulcate.

Types.—Figured Specimens: USNM 221420, USNM
221421, USNM 221423, USNM 221425, USNM

96 BULLETIN 313

221431, USNM 221433, USNM 221435, USNM
221437, USNM 221440, USNM 221441; Measured
Specimens: USNM 221411-221439.

Comparison.—Composita cf. C. pilula includes ma-
ture individuals of a smaller size than C. affinis Girty
(1909), C. apheles Cooper and Grant (1976a), C. ap-
sidata Cooper and Grant (1976a), C. cracens Cooper
and Grant (1976a), C. crassa Cooper and Grant
(1976a), C. emarginata Girty (1909), C. enormis Coo-
per and Grant (1976a), C. grandis Cooper (1957), C.
hapsida Stehli and Grant (1970), C. imbricata Cooper
and Grant (1976a), C. prospera Cooper and Grant
(1976a), C. stalagmium Cooper and Grant (1976a), C.
strongyle Cooper and Grant (1976a), C. subtilita (Hall,
1852) and C. subtilita peruviana Chronic (1949), and
of a larger size than those of C. bucculenta Cooper
and Grant (1976a), C. costata Cooper and Grant
(1976a), C. mexicana (Hall, 1857), C. miniscula
Chronic (1949) and C. nucella Cooper and Grant
(1976a). C. cf. C. pilula is generally more parasulcate
than C. minuscula, C. subtilita or C. subtilita peru-
viana, and less parasulcate than C. bucculenta and C.
parasulcata Cooper and Grant (1976a). C. pyriformis
Cooper and Grant (1976a), of the same mature size as
C. cf. C. pilula, has a more distinctly trigonal outline,
while C. emarginata is distinguished by its markedly
emarginate anterior commissure. C. parasulcata,
which occurs in the Road Canyon and younger units
in the West Texas region, is very similar to C. cf. C.
pilula, but, in addition to its greater degree of para-
sulcation, is more distinctly transverse in outline. C.
pilula of the West Texas region tends to be somewhat
more globose than the Palmarito specimens tentatively
referred to the species, and contains dental plates that
are fused to the apical walls along their entire length,
in contrast to their free-standing situation in the Ven-
ezuelan specimens.

Discussion.—Composita is an extremely conserva-
tive genus that contains variable and intergrading
species. A single specimen of Composita could rarely
be identified to species: large samples of populations
are required to determine such taxonomically signifi-
cant parameters as size of mature individuals, modal
shape, outline, and variations in the development of
fold and sulcus. The numerous species erected by
Cooper and Grant (1976a) contain some stratigraphic
input: the Wolfcampian species C. bucculenta con-
tains many individuals which would be indistinguish-
able from those of C. parasulcata or C. pilula. Cer-
tainly in these taxa we are dealing with distinct
populations of closely related brachiopods: whether or
not these populations truly represent distinct biologi-
cal species has not been demonstrated to my satisfac-

tion. It is for this reason that the Palmarito Composita
is only tentatively assigned to C. pilula Cooper and —
Grant.

Material.—
Articu-
Local- lated Dorsal Ventral Type of

ity Valves Valves Valves Preservation

calcite permineralization
fine silicification

fine silicification

calcite permineralization
fine silicification

fine silicification

coarse silicification

fine silicification

oo
RaRRASNH
S || oe ll Se |
ee @aaS ll = all

Suborder SPIRIFERIDINA Waagen, 1883

Superfamily CYRTIACEA Frederiks, 1924

Family AMBOCOELIIDAE George, 1931
Genus COSTICRURA new genus

Etymology of Name.—L. costa = rib; L. crura =
legs, shanks [used to connote affinity to Crurithyris
George (1931)].

Description.—Unequally biconvex, commonly
transverse, having ventral valve deeper than dorsal;
hingeline straight, anterior and lateral margins gently
rounded, cardinal extremities acute to obtuse, anterior
commissure rectimarginate; ventral valve slightly flat-
tened anteromesially, dorsal valve gently rounded in
anterior aspect; valves costate; costae low, rounded,
straight, extending from beaks to margins.

Ventral valve hemipyramidal, considerably inflated,
having high, ventral to apsacline interarea, high, open:
delthyrium, and straight hingeline.

Dorsal valve more flatly convex, low beak rarely
produced posterior to hingeline. Interarea very low,
dorsal to anacline, having small open notothyrium.

Ventral interior without dental plates, median sep-
tum or recognizable muscle attachment scars. Short
simple teeth at anterior edges of delthyrium.

Dorsal interior having simple paired sockets, unsup-
ported by socket plates; cardinal process inset, bilo-
bate, divided by relatively coarse simple median ridge. ©
Crural plates long, delicate, arising from posterior
valve floor anterodorsal of sockets, curving gently an-_
teroventrally and mesially to about midvalve, there’
turning ventrally, closely appressed; a short distance’
anteriorly becoming flattened, broadened, recurving:
laterally toward opposite valve walls, then mesially:
recurved, initiating first whorl of spiralium.

Type Species.—Costicrura minuta new species.

!
|
|

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 97

Diagnosis.—Costate Ambocoeliidae, lacking fold or
sulcus.

Occurrence.—Costicrura has to date been re-
covered only from locality 6, blocks A, B and C, in
the Palmarito Formation of Venezuela. A very small
“ribbed Crurithyris’’ was noticed in acid etch residues
from Permian rocks of Thailand (Grant, 1975, pers.
comm.), but since this was not recovered, its relation-
ship to Costicrura cannot be ascertained.

Comparison.—Costicrura is easily distinguished
from the other Permian ambocoeliid genera Cruri-
thyris George (1931) and Attenuatella Stehli (1954), by
its costate ornament and lack of fold or sulcus. It is
distinguished from the finely costellate genus Wilber-
rya Yancey (1978), by its less globose anterior profile,
its acuminate cardinal extremities, and its coarser ra-
dial ornament.

Discussion.—It is likely that further occurrences of
Costicrura will be reported from the Permian Tethyan
realm, as more studies of silicified faunas are under-
taken. The extremely small size of the Palmarito
species may be typical of the genus. If so, only picking
of fine size fractions of acid etch residues could yield
specimens of this elusive genus. The small size would,
in addition, preclude recovery of these forms from fau-
nas preserved by other modes than silicification.

Costicrura minuta new species
Plate 8, figures 39-44

Etymology of Name.—L. minuta = small.

Description.—Minute, unequally biconvex, trans-
verse, having straight hingeline; hinge width varying
from slightly less than to slightly more than midwidth,
commonly about one and one-half times as wide as
long. Anterior commissure rectimarginate, lacking dis-
tinct fold or sulcus; ventral valve straight-sided, flat-
crested in anterior aspect, high triangular in lateral
aspect; dorsal valve low, gently and broadly rounded
in anterior and lateral aspects. Both valves costate;
costae extending from beaks to margins.

Ventral valve hemipyramidal, considerably inflated,
having high, ventral to apsacline interarea, high, open
triangular delthyrium, and straight hingeline.

Dorsal valve shallowly convex, low beak produced
slightly posterior to hingeline. Very low, dorsal to an-
acline interarea having small open triangular noto-
thyrium.

Ventral interior without dental plates, median sep-
tum or recognizable muscle attachment scars. Short
simple teeth at anterior edges of delthyrium.

Dorsal interior having simple paired sockets, unsup-
ported by socket plates; cardinal process inset, bilo-
bate, divided by relatively broad simple median ridge.

Crural plates long, delicate, arising from posterior
valve floor anterodorsal of sockets, curving gently an-
teroventrally and mesially to about midvalve, there
closely appressed, turning ventrally, a short distance
anteriorly becoming flattened, broadened, recurving
laterally toward opposite valve walls, then mesially
recurved, initiating first whorl of spiralium.
Measurements (in mm).—

Total Hinge Mid- Thick-
Length Width Width ness

LOcALITy 6

(block A)
USNM 221442 1.1 1.3, 1.6 0.9
USNM 221443 1.2 1.2, 1.7 Hee
USNM 221444 1.2 1.4 1.6 1.0
USNM 221445 1.3 1.5, 1.8 1.1
USNM 221446 1.3 -7/ 1.8 1.2
USNM 221447 1.4 1.6 1.8 1.3
USNM 221448 1.4 7/7 1.9 1.2
USNM 221449 1.4 1.8 1.8 1.2
USNM 221450 1.4 1.8 1.9 1.3
USNM 221451 1.4 1:9 1.8 2

LOCALITY 6

(block B)
USNM 221452 0.9 1.0, 1.3 0.8
USNM 221453 1.5 2.3 Dal 1.4
(holotype)

LOCALITY 6

(block C)
USNM 221454 0.7 0.7 1.0 0.5
USNM 221455 0.7 0.9 1.0 0.5
USNM 221456 0.8 1.1 12 0.6
USNM 221457 0.9 0.9 1.1 0.5,
USNM 221458 1.0 1.2 1.3 0.8
USNM 221459 1.1 1.4 1.6 0.9
USNM 221460 1.1 1.5 1.6 1.0
USNM 221461 ile 115) lea 1.0
USNM 221462 12 1.6 slag 1.1
USNM 221463 1.2 1.4, 1.8 1.0
USNM 221464 1.2, 1.6, 21, 1.2,
USNM 221465 1.4 1.9 1.8 1.3
USNM 221466 1.4, 2 2.0 1:25

Occurrence.—as for genus.

Diagnosis.—Minute Costicrura.

Types.—Holotype: USNM 221453; Figured Speci-
mens: USNM 221453, USNM 221467, USNM 221468;
Measured Specimens: USNM 221442-221466.

Comparison.—C. minuta is the only species of the
genus.

Discussion.—The small ‘‘ribbed Crurithyris’’ men-
tioned above, from the Permian of Thailand, if related
to Costicrura minuta, probably represents a different
species. It is hoped that examination of fine size frac-
tions of Permian acid etch residues will yield compar-
ative material.

98 BULLETIN 313

Material.—
Articu-
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation
6 (block A) 13 5 7 fine silicification
6 (block B) 3 3 _ fine silicification
6 (block C) 16 14 7 fine silicification

Superfamily RETICULARIACEA Waagen, 1883

Family ELYTHIDAE Frederiks, 1924

Genus NEOPHRICADOTHYRIS Likharev, 1934

Type Species.—Squamularia asiatica Chao, 1929,
p. 91, pl. 11, figs. 12-14, by original designation of
Likharev, 1934, pp. 211, 213.

Diagnosis.—Spiriferacea having biramous spines in
concentric rows and the spiral axes coiled postero-
laterally.

Occurrence.—Neophricadothyris is a Permian rep-
resentative of a stock of elythids that range from the
Lower Carboniferous through the highest stage of the
Permian. In the Permian its geographic range is truly
cosmopolitan. In the Palmarito Formation it has been
recovered from localities 1, 7 and 8. It is rare at lo-
cality 1, common at locality 8 and abundant at local-
ity 7.

Comparison.—Neophricadothyris differs from
Squamularia Gemmellaro (1899) in its biramous
spines, narrower, posteriorly directed and more nu-
merous coils of spiralia, and its apparent more evenly
concentric ornament. It differs from Phricadothyris
George (1932), in its posterolaterally, rather than lat-
erally directed spiralia. Martinothyris Minato (1953)
and Nebenothyris Minato (1953) differ in having dental
plates or strong median septa internally, but Maxwell
(1961) has noted that both are invalid on nomenclatural
grounds as well. Condrathyris Minato (1953) is appar-
ently (fide Cooper and Grant, 1976a, p. 2247) a junior
synonym of Phricadothyris.

Pavlova (1965) studied the type species of the genus,
Squamularia asiatica Chao (1929), and determined
that it is not distinct from species of Phricadothyris.
Permophricodothyris Pavlova (1965) was introduced
to accommodate those forms, such as the Palmarito
species, in which the spiral axes are directed postero-
laterally. I concur with Cooper and Grant (1976a, p.
2248) in supporting the validity of Permophricodothy-
ris, but have retained the name Neophricadothyris, in
order that the Venezuelan and West Texas species
may be less ambiguously comparable.

Neophricadothyris cf. N. crassibecca
Cooper and Grant
Plate 8, figures 45-57

cf. Neophricadothyris crassibecca Cooper and Grant, 1976a, p.
2253, pl. 638, figs. 1-33.

Description.—Small to medium-sized, average sized
for genus, strongly biconvex; outline variable, sub-
pentagonal to subelliptical, juveniles commonly trans-
verse, mature individuals commonly more elongate;
greatest width near midlength of shell; commissure
rectimarginate in juveniles, becoming weakly unipli-
cate in more mature individuals; fold very low, not
normally expressed posterior to commissure, sulcus
more prominent, shallow, arising about 10-15 mm an-
terior to ventral beak; concentric lamellae moderately
strong, variable in density, from four to 14 in a 5 mm
distance at about midlength of mature individuals;
each lamella bearing one or two rows of double-bar-
relled spines; growth lamellae unevenly spaced, lo-
cally crowded.

Ventral valve strongly convex, greatest height pos- |

terior to midvalve; beak commonly thickened, blunt,
strongly curved, erect to slightly incurved; interarea
curved, narrow, outlined by poorly defined beak

ridges; delthyrium nearly equilaterally triangular, lat- —

erally bounded by low deltidial flanges, leaving del-
thyrium entirely open.

Dorsal valve less strongly convex; low beak in some
mature specimens partially blocking delthyrium; in-
terarea flat to slightly concave, of moderate height,
broken by low, broad notothyrium; low flanges bound-
ing margins of notothyrium.

Ventral interior having very short, pointed, slightly
hooked teeth; dental ridges weak to moderately
strong, united below delthyrial apex, not obstructing
delthyrium; muscle area weakly to strongly impressed,
elongate subelliptical to heart-shaped (in latter case

bisected by very low narrow median ridge), commonly —

longitudinally striate, migrating anteriorly during on-
togeny; earlier, posterior traces covered by secondary
callus shell material. Adductor marks commonly pres-
ent, diductor marks rarely preserved.

Dorsal interior having comparatively large hinge
sockets, socket ridges having tooth-like swellings an-
teriorly; cardinal process small, poorly defined; heli-
cophores and spiralia not preserved in silicified spec-
imens, but axes of coiling generally divergent toward
posterior, trending from lateral toward posterior ori-

entation during course of ontogeny; muscle area nar- |
row, elongate, weakly striate, sides slightly divergent |

anteriorly, bisected by very low, narrow median ridge.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 99

Measurements (in mm).—

Maxi-

Dorsal Maxi- mum

Total Valve Hinge mum Thick-

Length Length Width Width ness

LocaLity 7

USNM 221469 10.3 8.8 8.4, 11.8 11.7
USNM 221470 11.8 10.8 9.6. 13.1 9.5
USNM 221471 13.5 11.8 8.6, 14.0 9.8
USNM 221472 15.0 13.5 10.7. 16.1 11.3
USNM 221473 15.3 13.8 10.3, 16.1 12.2

USNM 221474 16.8 15.5 10.9, 17.8 13.0
USNM 221475 16.9, 15.5, 11.1, 18.6, 11.9,

USNM 221476 17.5 15.4 9.6. 18.2 V5
USNM 221477 18.7 15.8 11.8, 19.5 13.7
USNM 221478 18.8 119272 10.7. 15.5 13.0
USNM 221479 20.7 18.5 14.6, 20.8 14.6
USNM 221480 = 21.5 19.4 14.2, 21.0 14.8
USNM 221481 21.8 18.8 15.5 21.0 16.1

USNM 221482 22.0 MES 16.0, 21.9 15.8
USNM 221483 23516 19.6, 14.1, 21.0. 17.4,
USNM 221484 =. 23.1 20.0 1523. 24.0 17.1

USNM 221485 24.5 19.3 11.9, 22.4 18.8

USNM 221486 26.2 21.9 16.1, 25.2 18.9

USNM 221487 26.4 22.5 16.8, 24.6 19.5
Loca.ity 8

USNM 221488 — — 14.8 21.8 17.4

USNM 221489 = 25.2 aes) 14.1 20.1 20.2.

Occurrence.—In the West Texas region where it
was first described N. crassibecca occurs only in the
Road Canyon Formation (Late Leonardian). A very
closely related species, N. bullata Cooper and Grant
(1976a), has been recovered from the Bone Spring,
Hess, Cathedral Mountain and Road Canyon Forma-
tions, of from Late Wolfcampian to Late Leonardian
age. In the Palmarito Formation individuals here ten-
tatively referred to N. crassibecca but also similar to
N. bullata have been recovered from localities 1, 7
and 8. An Early Permian age for the assemblages re-
covered from these localities is not inconsistent with
other biostratigraphic indicators.

Diagnosis.—Strongly biconvex, apically thickened
Neophricadothyris having variable outline and orna-
ment.

Types.—Figured Specimens: USNM 221469, USNM
221472, USNM 221479, USNM 221485, USNM
221487, USNM 221488-—221493; Measured Specimens:
_USNM 221469221489.

Comparison.—Neophricadothyris cf. N. crassibec-
ca in the Palmarito Formation is an extremely variable
species. It is easily distinguished from some of the
West Texas species of the genus. N. catatona Cooper
_ and Grant (1976a) is much larger and more transverse,

while N. transversa Cooper and Grant (1976a) is more
uniformly transverse throughout its ontogenetic de-
velopment. Mature individuals of N. conara Cooper
and Grant (1976a) are smaller than those of N. cf. N.
crassibecca while similar ontogenetic stages of N.
guadalupensis (Shumard, 1859) are larger, more com-
monly elongate, and have a flatter dorsal valve and
higher deltidial flanges and dental ridges. Squamularia
guadalupensis R. E. King (1931) included individuals
assignable to two distinct species, N. bullata and N.
conara, and cannot thus be directly compared to N.
cf. N. crassibecca. In the West Texas area, several
characters serve to distinguish suites of N. bullata, N.
cordata and N. crassibecca. The Venezuelan speci-
mens are most similar to the West Texas N. crassi-
becca, but, because they are more variable than
known individuals of that species, they intergrade
more extensively with other similar species. In the
West Texas region, N. crassibecca is distinguished
from closely related species by its small size, pentag-
onal or elliptical outline, crowded concentric lamellae,
each bearing but a single row of double-barrelled
spines, its great biconvexity, and its thickened ventral
umbonal region. In the Venezuelan specimens only
the last of these characters appears to be consistently
different from other known species, except N. cras-
sibecca. This single feature alone is clearly insufficient
for erection of a new species. N. cf. N. crassibecca
differs from the Bolivian Permian Phricodothyris sep-
tata Chronic (1949) in lacking a median septum in the
ventral valve, and from Phricodothyris guadalupensis
peruensis Chronic (1949) in the larger size of its mature
individuals.

Discussion.—Cooper and Grant (1976a, p. 2254)
have suggested that N. crassibecca may indeed be
considered a subspecies of N. bullata. It does seem
very difficult to differentiate in an objective manner
between the various species of Neophricadothyris that
have been erected. Perhaps the feeling that organisms
must evolve through time has led to the expression of
specific differences where only population variation
exists. If, as has been suggested (e.g., Eldredge and
Gould, 1972, pp. 82 ff.) speciation does take place near
the extremes of the geographic range of a species, it
becomes more realistic to consider that the species
bullata, crassibecca and cordata may be separable in
the West Texas region, yet occur within a single pop-
ulation in Venezuela. A similar situation apparently
occurs in the relationship of Texan and Venezuelan
species of Cooperina Termier, Termier and Pajaud
(1966).

Several of the Venezuelan specimens from locality
7 do not follow the common ontogenetic pattern in

100

form development. These more elongate individuals
may be responding to the same sort of crowding pres-
sures noted in population samples of Hustedia hypo-
rhachis n. sp. from locality 10, Palmarito Formation.
Certainly, equivalent positions of faunal dominance
are attained by Hustedia Hall and Clarke (1893) at
locality 10 and Neophricadothyris at locality 7, and to
a lesser degree, at locality 8.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
1 2 — 5 calcite permineralization
7 110 11 40 calcite permineralization
8 6 U 36 fine silicification

Superfamily SPIRIFERACEA W. King, 1846
Family SPIRIFERIDAE W. King, 1846
Subfamily NEOSPIRIFERINAE Waterhouse, 1968

Genus NEOSPIRIFER Frederiks, 1924

Type Species.—Spirifer fasciger Keyserling, 1846,
in Keyserling and Krozenstern, p. 231, pl. 8, figs. 3-
3b (by original designation of Frederiks, 1924, p. 311).
Lectotype = Spirifer fasciger Keyserling, 1846, pl. 8,
fig. 3b (non figs. 3, 3a = species unknown) (by des-
ignation of Cooper and Grant 1976a, p. 2173).

Diagnosis.—Spiriferidae with fasciculate costae,
without scaly, raised growth laminae, and with fine
radial ornamentation weak or absent.

Occurrence.—Neospirifer ranges through Pennsyl-
vanian and Permian strata, and in the Permian has a
cosmopolitan distribution. In the Palmarito Forma-
tion, it has been recovered from localities 1 and 7,
where it is common, and localities 4 and 8 where it is
rare.

Comparison.—Neospirifer is distinguished from
Aperispirifer Waterhouse (1968), an Asian and Aus-
tralian genus, by the absence of any delthyrial plate
in juvenile or early mature stages of that form. Car-
torhium Cooper and Grant (1976a) is distinguished by
its more rounded flanks, consistently triangular ventral
interarea, subelliptical or rarely transverse outline,
and limitation of its costal bifurcations to the posterior
part of the valves. Fusispirifer Waterhouse (1966) is
generally far more transverse, and has much fainter,
lower radial ornament, and a more massive delthyrial
plate. Grantonia Brown (1953), from the Permian of
Southeast Asia and Australia, is generally similar to
Neospirifer but has stronger, less numerous fascicles,

BULLETIN 313

and greatly thickened shells. Gypospirifer Cooper and
Grant (1976a) has more numerous, finer, not distinctly
fasciculate costae, and no real plications of the com-
missure except the median fold itself. Lepidospirifer
Cooper and Grant (1969) differs in having weaker fas-
ciculation, finer costae, scaly ornamentation and a
straighter beak, with the apical plate small, low, and
normally fused to the floor of the valve. Spiriferinaella
Frederiks (1926) differs in having non-fasciculate cos-
tae. Trigonotreta Koenig (1825) bears costae which
bifurcate only once, in an extremely regular fashion,
in contrast to the condition of Neospirifer.

Neospirifer venezuelensis (Gerth)
Plate 9, figures 1-13

Spirifer cameratus Morton var. venezuelensis Gerth in Gerth and
Krausel, 1931, p. 525, pl. 22, figs. 3-4 (non Spirifer venezuelensis
Weisbord, 1926, p. 19, 20, pl. 4, fig. 6).

Neospirifer thescelus Cooper and Grant, 1976a, p. 2189, pl. 609,
figs. 30-48; pl. 610, figs. 1-38; pl. 611, figs. 1-12; pl. 612, figs. 1-
12.

Description.—Large, strongly biconvex; outline ir-
regularly semi-elliptical to subpentagonal or trapezoi-
dal, normally widest at hinge but only slightly alate;
commissure uniplicate medially, slightly undulating
laterally; fastigium narrow, high anteriorly on larger
shells; sulcus deep, broadly V-shaped in cross section,
well-defined laterally by sharp costae. Costae strongly
fasciculate, fascicles forming four to five plications on
either flank of shell, progressively weaker laterally,
commonly with prominent mesial costa arising at
beak, subsidiary costae arising anteriorly by bifurca-
tion, up to eight per fascicle, most on mesial fascicles;
median costa of fastigium bifurcating near beak, con-
tinuing anteriorly as dual crest, bifurcating laterally
only anteriorly. Median costa of sulcus narrowly bi-
furcated near beak, continuing to commissure, other

costa in sulcus produced by lateral bifurcations of sul- —

cus-bounding costae. Fine radial ornament absent;
concentric ornament of fine, closely spaced growth
lines, interrupted by stronger, irregularly spaced
growth laminae, laminae becoming more frequent to-
ward margins.

Ventral valve strongly convex transversely and lon-
gitudinally, greatest convexity posteriorly, shell thick-

ened along hinge in large individuals; beak strongly _
hooked, overhanging open, triangular delthyrium; |

pseudodeltidium apical or absent, rarely preserved;
interarea concave, commonly faintly striate longitu-
dinally, extending to cardinal extremities; edge of
hinge bearing numerous short denticles, apparently
serving as articulatory processes.

Dorsal valve less strongly convex, produced only

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 101

slightly posterior to hinge; interarea low, slightly con-
cave, but equal in width to ventral counterpart; no-
tothyrium wide, low, apex bearing low, longitudinally
finely striate cardinal process.

Ventral interior bearing strong, but very short,
knob-like, anteriorly diverging teeth, supported by
thick, deep dental ridges; ridges commonly converging
toward valve floor; dental plates continuous with den-
tal ridges apically, diverging to intersect floor on either
side of muscle attachment area, in larger shells partly
obscured laterally by secondary shell growth, callus
material also commonly filling apical cones. Muscle
area elongate oval, commonly excavate apically,
slightly elevated anteriorly in larger shells; adductor
marks elongate, narrow, lightly striate longitudinally,
lying along each side of low, thin median ridge; di-
ductor marks large, lateral to adductors. Floor of valve
along hinge pitted and pustulose in irregularly radiat-
ing pattern. Pattern fading anteriorly.

Dorsal interior having widely divergent, thick-
walled hinge sockets, non-functional posteromesial
portions roofed by thin plates. Helicophores, spiralia
not observed. Muscle attachment area elongate, bi-
sected by low, sharp median ridge; exterior plications
strongly reflected on remainder of surface. Median
sulcus (reflection of external fold) bearing narrow shal-
low parallel furrows, running anteroventrally from
midline toward sulcal margins.

Measurements (in mm).—

Dorsal

Total Valve Hinge Mid-_ Thick-

Length Length Width Width ness
USNM 221494 S2e 46. 6956 62, 21,
USNM 221495 58 45 67 pe 60 40,
USNM 221499 48 37 52 55 33
(plastolectotype)
USNM 221500 40 36 60, 60h 30

(plastoparalectotype)

Occurrence.—In his discussion of the Palmarito
Formation Gerth (in Gerth and Krausel, 1931, p. 524)
stated:

. . . Der Fusulinenkalk geht in kalkig-mergelige Lagen tiber, die die
folgenden Fossilien geliefert haben:

Spirifer cameratus Mort. var. venezuelensis Gerth

Seminula argentea Shep.

A fusulinid-bearing limestone occurs high in the Pal-
marito Formation and has been noted both in the type
section and in the reference section established by
Arnold (1966). Specimens of Neospirifer venezuelen-
sis from localities 1, 4, 7 and 8 in the present study
cover most of the stratigraphic extent of the formation.

The form described as N. thescelus Cooper and Grant
(1976a), has been recovered only from the (Late Le-
onardian) Road Canyon Formation of West Texas. A
latest Leonardian age for the cited localities in the
Palmarito Formation is not inconsistent with other
biostratigraphic indicators.

Diagnosis.—Large, thick Neospirifer having strong
costae and prominent fascicles producing plications,
wide hinge but short or absent alae, and a moderately
deep sulcus.

Types.—Lectotype: NHB L4453; Paralectotype:
NHB L4452; Figured Specimens: USNM 221494—
221500; Measured Specimens: USNM 221494-221495,
USNM 221499221500.

Comparison.—N. venezuelensis is easily differen-
tiated from N. cameratus (Morton in Hildreth, 1836),
as a variety of which it was first described, by its much
stronger ornament of both costae and fasciculate pli-
cae. The average size of mature individuals of N. ven-
ezuelensis is greater than that of the West Texas
species N. apothescelus Cooper and Grant (1976a)
and N. formulosus Cooper and Grant (1976a). It is
less alate, or mucronate, than the West Texas species
N. amphigyus Cooper and Grant (1976a), N. bakeri
bakeri R. E. King (1931), and N. bakeri columbiarus
Cooper and Grant (1976a). N. huecoensis R. E. King
(1931) is less strongly uniplicate. N. mansuetus Coo-
per and Grant (1976a), N. notialis Cooper and Grant
(1976a), and N. placidus Cooper and Grant (1976a)
share the lower, less marked radial ornament that is
more characteristic of N. cameratus than of N. vene-
zuelensis. N. neali Cooper and Grant (1976a) is seldom
as long-hinged as is N. venezuelensis, and has a long-
er, more strongly apsacline interarea. The character-
istic dual crest of the fold distinguishes N. venezuelen-
sis from the North American mid-Continent species
N. triplicatus (Hall, 1852) and N. latus Dunbar and
Condra (1932). It is effectively distinguished from Spi-
riferella pseudocameratus (Girty, 1920), commonly
considered a species of Neospirifer, by the pustulose
surface ornament which places that form within the
Brachythyrididae.

Discussion.—Cooper and Grant (1976a) described
the species N. thescelus, understandably having over-
looked Gerth’s (in Gerth and Krausel, 1931) compar-
atively obscure publication of §. cameratus var. vene-
zuelensis. Although the Palmarito suite of N.
venezuelensis is small, such diagnostic characters as
the very strong fasciculate plicae and the dual crest of
the fold demonstrate the synonymy of N. venezuelen-
sis and N. thescelus.

N. venezuelensis was first described on the basis of
specimens provided to Gerth by the collector, Peter

102 BULLETIN 313

Christ, who published the first account (Christ, 1927)
of the Palmarito Formation. The specimens (two syn-
types) are part of the collections of the Basle Natur-
historisches Museum. A holotype was not designated,
possibly because Gerth described the form as a new
variety of an existing species, rather than as a new
species. To clarify future comparisons, I have here
designated these as lectotype (NMB L4453) and para-
lectotype (NMB 14452). The International Code of
Zoological Nomenclature (ICZN, 1961, Art. 45, sect.
d, part ii) clearly states that a variety or form erected
before 1961, if it has inherent geographic significance,
may be considered of infraspecific, rather than infra-
subspecific status, and therefore available for eleva-
tion to specific status when the generic designation is
changed. Casts of the Swiss type specimens have been
included with the present topotypic material as bases
for the descriptions, and are figured here (PI. 9, figs.

8, 9).
Material.—
Articu-
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation
1 2 — 1 calcite permineralization
1 — 1 — internal cast
1 — — 1 external mold
4 — — 1 coarse silicification
7 4 5 12 calcite permineralization
8 1 — — fine silicification
unknown* 2 — _ calcite permineralization

* purchased from child at type locality of Palmarito Formation

Superfamily SPIRIFERINACEA Davidson, 1884

Discussion.—According to the Treatise (Boucot et
al., in Williams et al., 1965, p. H711) the Spiriferi-
nacea consists of a single family including 19 genera
ranging in age from Early Carboniferous to Early Ju-
rassic. Only seven of these occur in the Permian. In
the revision of the superfamily (Cooper and Grant,
1976b, p. 2666), the impunctate forms Odontospirifer
Dunbar (1955) and Spiriferinaella Frederiks (1926)
were removed on that basis. In addition, Paraspirif-
erina Reed (1944) was removed from synonymy with
Callispirina Cooper and Muir-Wood (1951), and re-
designated a valid genus. Three new genera, Metri-
olepis Cooper and Grant 1976b), Arionthia Cooper
and Grant (1976b) and Scenesia Cooper and Grant
(1976b), plus two others, Sarganostega Cooper and
Grant (1969) and Xestotrema Cooper and Grant
(1969), thus brought the total number of Permian spi-
riferinacean genera to 11, which were distributed in

six new families: Reticulariinidae, Crenispiriferidae,
Paraspiriferinidae, Sarganostegidae, Xestotrematidae
and an un-named family containing the single genus
Scenesia. While this arrangement has some draw-
backs (non-spinose Spiriferellina [sensu Frederiks,
1924] are included in the Reticulariinidae, of which a
diagnostic character is that genera included in it bear
large hollow spines on the exterior), it 1s followed
here, since it results from study of faunas very similar
to the Venezuelan ones, and because it is the most
recent comprehensive study of its kind.

Family RETICULARIINIDAE
Cooper and Grant, 1976b

Genus SPIRIFERELLINA Frederiks, 1924

Type Species.—Terebratulites cristatus Schlotheim,
1816, p. 16, pl. 1, figs. la—c, by original designation of
Frederiks, 1924, p. 299.

Diagnosis.—Typically small, transversely rounded,
having flat-crested, low fastigium, few lateral plica-
tions, irregularly spaced growth lines; surface smooth
or having many small low pustules; cardinal process ©
narrow, crural plate broad, forming small apical plat-
form. |

Occurrence.—Spiriferellina is a nearly cosmopoli-
tan Permian genus, having been recovered from both
the Tethyan and Boreal realms. It has not to date been
recognized in Australia or New Zealand.

Comparison.—Spiriferellina is easily distinguished
from the other two Permian Reticulariinidae, Reticu-
lariina Frederiks (1916) and Altiplecus Stehli (1954),
by the conspicuous hollow ornament spines of these
genera, which are never present in species of Spirif-
erellina.

Discussion.—Due to an initial oversight by Fred-
eriks (1924), who named Terebratulites cristatus
Schlotheim (1816) as the type of the genus Spirifer-
ellina, none of Schlotheim’s specimens was cited, and
reference was instead made to descriptions and illus-
trations by Tschernyschev (1902). Frederiks also cited
a Bolivian Permian species, S$. campestris (White,
1874) Kozlowski (1914), since demonstrated (Chronic,
in Newell et al., 1953; Cooper and Grant, 1976b) to
belong in Reticulariina.

With this confusion, Spiriferellina easily became a
catch-all genus for punctate spiriferoids, often without |
regard to comparison with its type species S. cristata.
Campbell (1959) clarified the relationships of some spi-
riferinaceans by redescribing type materials of Punc-.
tospirifer North (1920), Reticulariina and Spiriferel-
lina. Cooper and Grant’s (1976b, p. 2666 ff.))
separation of the former family Spiriferinidae into six,

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 103

new families, each distinguished on clear morpholog-
ical grounds, is clearly a step towards a more system-
atic, if not more realistic treatment of these punctate
forms.

Spiriferellina cf. S. hilli (Girty)
Plate 8, figures 58-71; Plate 9, figures 28-29

cf. Spiriferina hilli Girty, 1909, p. 379, pl. 30, figs. 15—15b.
cf. Spiriferellina hilli (Girty), Cooper and Grant, 1976b, p. 2703, pl.
704, figs. 18-25; pl. 709, figs. 18-71.

Description.—Small, average sized for genus, un-
equally biconvex; subovate to transversely subellip-
tical in outline; hinge wide, cardinal extremities com-
monly rectangular or slightly extended; commissure
plicated by median fold and three to four, most com-
monly three lower plications on each flank; plications
separated by nearly equally wide troughs, all arising
at beaks or along hingeline; median plication widening
anteriorly, in lateral aspect rising slightly above more
tightly curved lateral plications; crest of plication flat-
tened at beak, remaining flattened toward anterior;
sulcus shallow, somewhat quadrate in cross section,
median trough flattened or slightly swollen to form low
ridge. Surface bearing low, rarely preserved pustules
between punctae; spines absent; growth laminae
strong, widely and irregularly spaced, somewhat more
crowded near margins.

Ventral valve moderately deep; beak prominent,
elongate or attenuate, apex bluntly pointed, moder-

ately to strongly curved; interarea broadly triangular,
apsacline, radius of curvature lessening towards apex;
delthyrium triangular, apically bearing short bridge
across median septum; deltidial plates not preserved.

Dorsal valve less strongly convex, fastigium in lat-
eral view nearly straight; beak bluntly pointed, inter-
area low, wide, slightly concave; notothyrium broad-
ly triangular, apex bearing narrow, ventrally striate
cardinal process.

Ventral interior having short, knob-like teeth; dental
ridges moderately strong, tapering anteriorly, con-
verging slightly toward midline of valve; dental plates
short, apical in adults, meeting dental ridges at about
one-half their length; median septum high, very thin,
abruptly sloping anteriorly, extending about one-third
to one-fourth valve length from apex. Muscle marks
on floor of valve and sides of septum insufficiently
well-preserved to distinguish adductors or diductors.

Dorsal interior having wide, open sockets, partially
roofed posteriorly by anterior edge of interarea; socket
ridges thick, slightly elevated anteriorly; hinge plates
attached to socket ridges, strongly deflected dorsally,
converging and fusing along midline to form concave
hinge plate, bisected by cardinal process ventropos-
teriorly, markedly notched anterodorsally; crura ex-
tending anteriorly from hinge plates, bowed outward,
then converging; jugal processes and spiralia not ob-
served. Muscle area elongate, mesial, undifferentiat-
ed.

Measurements (in mm).—

Dorsal
Total Valve Hinge Mid- Maximum Thick-
Length Length Width Width Width ness
Loca.ity 3

USNM 221501 2.4 2.0 2.4 2.4 1.8
USNM 221502 3.2 3:2 4.5 4.7 3.0
~ USNM 221503 3.5 3.2 4.8, 4.8, 3.0
USNM 221504 4.0 3.8 5.4, 5.4, 32
| USNM 221505 4.5 3.9 4.9 5.4, 3.6
USNM 221506 5.3 4.7 5.6, 7.0, 4.8
| USNM 221507 6.1 5.3 _ 6.0 — 4.8
USNM 221508 7.8 6.0 3 US 8.5 3)3)
USNM 221509 8.1 6.7 10.45, USS 10.44, 6.0
USNM 221510 8.0 6.3 10.3), 9.5 10.3, 2

| Occurrence.—Spiriferellina cf. S. hilli has been re-
covered from locality 3 of the Palmarito Formation.

S. hilli is known in the West Texas region from various
localities within the Word Formation (Guadalupian).
Such an age assignment is a bit younger than that in-
| dicated by other biostratigraphic indicators for the Pal-
marito locality, but is not beyond the realm of reason-
able possibility.

Diagnosis.—Transverse to nearly equidimensional
wide-hinged Spiriferellina with moderately flat dorsal
valve.

Types.—Figured Specimens: USNM 221501, USNM
221505, USNM 221506, USNM 221508, USNM
221510—221515; Measured Specimens: USNM 221501 -
221510.

Comparison.—S. hilli may easily be distinguished

104 BULLETIN 313

from S. paucicostata Cooper and Grant (1976b) by the
larger size of mature individuals of that species, and
from S. nuda Cooper and Grant (1976b) and S. cris-
tata (Schlotheim, 1816) by the smaller size of mature
individuals of those species. S. nasuta Cooper and
Grant (1976b) is characterized by a markedly elongate
interarea and ventral beak, while S. vescula Cooper
and Grant (1976b) is much more strongly biconvex.
The Late Leonardian species S$. tricosa Cooper and
Grant (1976b) is very similar to S. hilli, but differs in
the slightly larger size of mature individuals, its wider
hinge and its more abundant pustules. The Venezuelan
form here tentatively assigned to S. hilli differs from
that form in West Texas in its slightly more transverse
outline and its slightly higher fastigium. The outline of
S. cf. S. hilli from the Palmarito is quite variable, with
the hinge equal to or slightly less than the greatest
width of the shell. West Texas species seem less vari-
able, but whether this is ecologically caused or due to
over-splitting of taxa cannot be determined.

Discussion.—As in the Chonetacea, surface orna-
ment is used here as an important diagnostic character
at the generic level. Within any genus, specific differ-
entiation is not unduly difficult. Differences at the ge-
neric level however, are made less concise by the va-
garies of preservation: a hollow spine, if broken off,
may produce either a pustule-like prominence, a rec-
ognizable hollow-spine base, or no trace; differing de-
grees of decortication may produce surface punctae of
differing patterns or sizes. In taxonomic determina-
tions, presence of a morphologic feature is far more
significant than absence.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
3 18 11 10 fine silicification

Order TEREBRATULIDA Waagen, 1883
Suborder TEREBRATULIDINA Waagen, 1883
Superfamily DIELASMATACEA Schuchert, 1913
Family DIELASMATIDAE Schuchert, 1913
Subfamily DIELASMATINAE Schuchert, 1913

Genus ANEUTHELASMA Cooper and Grant, 1976b

Type Species.—Aneuthelasma amygdalinum Coo-
per and Grant, 1976b, p. 2906, pl. 762, figs. 26-61.

Diagnosis.—Dielasmatinae without dental plates
and with inner hinge plates widely separated where
they meet the valve floor.

Occurrence.—The genus Aneuthelasma has been
reported from the West Texas region, where it occurs
in the Capitan and Bell Canyon Formations (Guada-
lupian). The Venezuelan form assigned to the genus
is probably from a somewhat lower level.

Comparison.—Aneuthelasma differs from Dielas-
ma W. King (1859), Dielasmina Waagen (1882), Ec-
toposia Cooper and Grant (1976b), Fletcherithyris
Campbell (1965), Hoskingia Campbell (1965), Plec-
telasma Cooper and Grant (1969), Whitspakia Stehli
(1964) and Yochelsonia Stehli (1961a) by its total lack
of dental plates in the ventral interior. Hemiptychina
Waagen (1882) has an anteriorly plicate commissure,
and Camarelasma Cooper and Grant (1976b) and
Lowenstamia Stehli (1961b) both have inner hinge
plates in the dorsal valve, features that Aneuthelasma
lacks. Three genera known from the Permian of the
Australia-New Zealand area [Gilledia Stehli (1961a),
Maorielasma Waterhouse (1964) and Marinurnula
Waterhouse (1964)], are Dielasma-like terebratuloids
that also lack dental plates. These three have been
combined to form the Gillediidae (Campbell, 1965),
chiefly on that basis. Although Aneuthelasma and
some other Dielasmatidae would logically fit in that
family, I have considered it premature to relocate
these genera without knowing whether hinge structure ©
or presence/absence of dental plates is more signifi-
cant at the generic level. Of the three genera men-
tioned above, Gilledia may be distinguished from
Aneuthelasma by its commonly uniplicate anterior
commissure; Maorielasma, like most of the Dielas-
matidae, has inner hinge plates that combine to form
a septalium, and Marinurnula is a much larger shell,
with a distinct tendency toward folding of the anterior
commissure. Internally the genera of the Labaiidae
[Labaia Likharev (1956), Pseudodielasma Brill’
(1940), Oligothyrina Cooper (1956)] closely resemble
Aneuthelasma. The anterior commissures of the latter
two genera however are distinctly folded. The loop in’
those genera, as it arises from the crural bases, is more
robust, and the two parallel elements are more closely
appressed than is the case with Aneuthelasma. In ad-
dition, the outer hinge plates of the Labaiidae are sec-
ondary, while in Aneuthelasma they are not. Labaia
itself is poorly known: though it does not appear (Li-
kharev, 1956, pl. 72, fig. 3) to be folded, the interior —
is not shown and has only been very broadly defined |
(Stehli, 1965, p. H755).

Aneuthelasma globosum new species
Plate 9, figures 14—27

Etymology of Name.—L. globosus = rotund, glo-'
bose. |

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 105

Description.—Small, small for genus, subtriangular
to suboval to subpentagonal in outline, maximum
width about midvalve. Anterior commissure rounded,
straight. Valves nearly equal in depth. Surface
smooth.

Ventral valve evenly and moderately convex in lat-
eral view; broadly and evenly convex in anterior view,
with somewhat flattened flanks in older specimens.
Beak short, suberect to erect; umbonal region some-
what swollen, swelling absent at midvalve. Sulcus ab-
sent. Foramen small, slightly labiate; beak ridges
strong, rounded. Deltidial plates thin, disjunct, well-
defined.

Dorsal valve broadly convex in lateral and anterior
views. Beak small; umbonal region narrowly swollen,
anterior portion somewhat flattened.

Ventral interior without dental plates, but having a
well-defined, thick pedicle collar; muscle area ovate,
poorly defined. Teeth short, strong, hooked slightly
dorsoposteriorly.

Dorsal interior having strong socket ridges and pos-
terolaterally recurved fulcral plates; outer hinge plates
obsolete; crural bases broad; inner hinge plates very
short to absent, if present widely separated, contacting
valve floor vertically. Descending branches of loop
long, subparallel; transverse ribbon not observed.

Measurements (in mm).—

Occurrence.—Aneuthelasma globosum n. sp. has
been recovered only from locality 6, blocks A, B and
C, in the Palmarito Formation. The other known
species of the genus, A. amygdalinum Cooper and
Grant (1976b), is known from the Capitan and Bell
Canyon Formations in the West Texas Permian.

Diagnosis.—Small, globose Aneuthelasma.

Types.—Holotype: USNM 221520; Figured Speci-
mens: USNM 221516, USNM 221520, USNM 221522,
USNM 221523, USNM 221526, USNM 221529,
USNM 221530, USNM 221533; Measured Specimens:
USNM 221516-221532.

Comparison.—Aneuthelasma globosum is distin-
guished from the other known species of the genus,
A. amygdalinum, by its more rotund form and smaller
size of mature individuals. It may be distinguished
from the superficially similar form Pseudodielasma
brilli Cooper and Grant (1976b) by the slight tendency
of that form toward a uniplicate anterior commissure,
as well as its more narrowly appressed, more robust
crural bases. It differs from internally similar species
of Marinurnula Waterhouse (1964) and Gilledia Stehli
(1961la) in its decidedly equivalved condition and ab-
sence of anterior commissural plication or folding.

Discussion.—A. amgygdalinum is known only from
the Early Guadalupian of the West Texas region. Al-
though possible, it is unlikely, on the bases of other
Palmarito biostratigraphic indicators, that A. globo-

Dorsal sum is this young.
Total Valve Maximum Thick- Material.—
Length Length Width ness
LocaLity 6 Articu-
(block A) lated Dorsal Ventral Type of
USNM 221516 23 20 20 14 Locality Valves Valves Valves Preservation
USNM 221517 3.4, 3.1 eal 1.8 6 (block A) 12 3 3 fine silicification
USNM 221518 3.9, 3.5 3.4 b6 = 6 (block B) 15 9 5 fine silicification
USNM 221519 5.5, 4.7 4.5 3.1 6 (block C) 25 9 13 fine silicification
USNM 221520 6.1 5.5 5.4 3.4
(holotype)
LOcALity 6
(block B)
USNM 221521 2.9 PLD) 23 1S, :
USNM 221522 47 AR 36 29 Family PPREUDODIELASMATIDAE
USNM 221523 5.1 43 3.8 355... Cooper and Grant, 1976b
LOcALitTy 6
(block C) Genus OLIGOTHYRINA Cooper 1956
USNM 221524 3.0 2.6 2.5 1.6 Type Species.—Oligothyrina alleni Cooper, 1956,
99 9) >)
Meise mk cit A se pe p. 526, pl. 61, figs. 33-41.
USNM 221527 37 33 59 1.9, Diagnosis.—Small, with a weakly to strongly intra-
USNM 221528 3.8 33 3.1 4 plicate anterior commissure; folds arising anterior to
USNM 221529 4.0 3.5 3.4 DD) midlength; transverse band not projecting anteriorly.
Peis 221530 4.5 4.0 3.7 2.7 Occurrence.—Oligothyrina is known from rocks
221531 4.5 3.9 3.7» 3.0 . 7 j i
r fr Vv
“SN a ne me iS - anging in age from Middle Pennsylvanian to Early

Permian, in North America. The genus has tentatively

106 BULLETIN 313

been identified from the Chochal Limestone (Leonar-
dian) of Guatemala. It is also tentatively identified at
localities 3 and 13 of the Palmarito Formation, Vene-
zuela.

Comparison.—Oligothyrina is easily distinguished
from Pseudodielasma Brill (1940) by the paraplicate
anterior commissure of that genus, and from Pleure-
lasma Cooper and Grant (1976b) by the costate ante-
rior commissure of that genus, as compared to the
intraplicate commissure characteristic of Oligothyri-
na.

Discussion.—Oligothyrina has not been recognized
in the West Texas region. This is peculiar as few gen-
era present in the Palmarito Formation are neither
‘‘West Texas’’ genera nor new. Its absence there may
in some manner be facies-related, though no hard data
either support or negate that suggestion.

Oligothyrina? sp.
Plate 10, figures 1-4

cf. Oligothyrina? sp. Stehli and Grant, 1970, p. 34, pl. 12, figs. 1-
12; pl. 13, figs. 8-16.

Description.—Small, slightly small for genus,
strongly biconvex, teardrop-shaped in outline; beak
erect to slightly incurved; foramen somewhat telate;
anterior commissure intraplicate to antiplicate; ante-
rior face somewhat truncate. Surface smooth.

Ventral valve evenly convex, greatest depth about
midvalve; median portion of shell somewhat flattened
from about midvalve anteriorly.

Dorsal valve unevenly convex, greatest depth um-
bonal; beak small, narrow, not protruding much be-
yond outline of remainder of valve.

Interiors unknown.

Measurements (in mm).—

Dorsal
Total Valve Maximum Thick-
Length Length Width ness
LocaLity 3
USNM 221534 3.0 Des Del 1.8
USNM 221535 3.8 3.2 2.8 2.4
USNM 221536 4.1 3.6 3.0 3.1
USNM 221537 4.2 3.4 3.3 3.0
USNM 221538 4.4 3.6 3.0 2.9
Loca.Liry 13
USNM 221539 4.4 3.4 3.2 aH
USNM 221540 4.6 3.5 3.5 3.5

Occurrence.—Oligothyrina? sp. is here reported
from localities 3 and 13, of the Palmarito Formation,
Venezuela. Another terebratulid, larger than the Pal-
marito specimens, but also assigned tentatively to the
genus Oligothyrina was reported from the Chochal
Limestone, of Leonardian-equivalent age, of Guate-
mala (Stehli and Grant, 1970, p. 34). The type species
of the genus, O. alleni Cooper (1956), is known only
from North America, where it occurs in Pennsylvanian
strata.

Diagnosis.—Small, strongly biconvex Oligothyri-
na?, with width commonly equal to thickness.

Types.—Figured Specimen: USNM 221539; Mea-
sured Specimens: USNM 221534—221540.

Comparison.—Since the interior of the Venezuelan
form is entirely unknown, it cannot be directly com-
pared to such details in known species of Oligothyri-
na. It is, however, more strongly convex than either
O. alleni or O.? sp. Stehli and Grant (1970), and is
smaller than the latter form.

Discussion.—While the interior details of the Ter-
ebratulida are of great recognized importance in taxo-
nomic differentiation of that group, some distinctions
can nevertheless be made on the basis of external
characteristics, especially in the case of the distinctive
commissural folding of Oligothyrina.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
3 34 — — coarse silicification
13 2 —_— = coarse silicification

Suborder TEREBRATELLIDINA
Muir-Wood, 1955

Superfamily CRYPTONELLACEA Thomson, 1926
Family CRYPTONELLIDAE Thomson, 1926

Subfamily CRYPTACANTHIINAE Stehli, 1965
ANAPTYCHIUS new genus

Etymology of Name.—Gr. ana = not; Gr. pty-
chios = folded.

Description.—Small, subtriangular to subovate to
subpentagonal in outline, having broadly convex ven-
tral and dorsal valves; anterior commissure rectimar-
ginate, unfolded; shell gently rounded in lateral and

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

anterior views; beak suberect; umbonal region flat-
tened, broad in dorsal view, thin in lateral view; beak
ridges distinct, strong, rounded; foramen commonly
open, not labiate, rarely closed by thin disjunct deltid-
ial plates anteriorly in larger shells; surface smooth.

Ventral valve evenly convex, teardrop-shaped in
dorsal view; greatest depth commonly at midvalve;
greatest width commonly anterior thereto; foramen
submesothyridid; umbonal region distinctly swollen in
dorsal aspect; flattened in lateral view.

Dorsal valve evenly but more flatly convex than
ventral, without fold or commissural flexure; valve
subcircular in outline; outline broken by narrow, short
beak, beak protruding short distance into delthyrium;
greatest width and depth about midvalve.

Ventral interior having pair of small, blunt hinge
teeth; edges of delthyrium supported by strong dental
plates; muscle attachment areas posterior, elongate,
poorly differentiated, divided by low broad median
rise; valve floor in larger specimens thickened between
dental plates.

Type Species.—Anaptychius minutus n. sp.

Diagnosis.—Small, rectimarginate, unfolded Crypt-
acanthiinae.

Occurrence.—Anaptychius is known only from lo-
cality 6, blocks A, B and C, of the Palmarito Forma-
tion.

Comparison.—Anaptychius is distinguished from
Cryptacanthia White and St. John (1867) and Gacina
Stehli (1961b) by its rectimarginate, unfolded shell,
and from Glossothyropsis Girty (1934) by that feature
and its lack of a dorsal median septum.

Discussion.—The loop and hinge of Anaptychius
unequivocally link it with the Cryptacanthiinae. I de-
cided to expand the bounds of that subfamily to re-
ceive unfolded shells, rather than to erect a new
subfamily. The small size of this shell may in part
account for its previous obscurity.

107

Anaptychius minutus new species
Plate 10, figures 5—17

Etymology of Name.—L. minutus = minute.
Description.—Minute to small, small for genus, sub-

triangular to subovate to subpentagonal in outline,
having broadly convex ventral and dorsal valves; an-
terior commissure rectimarginate, unfolded; shell
gently rounded in lateral and anterior views; beak sub-
erect; umbonal region flattened, broad in dorsal view,
thin in lateral view; beak ridges distinct, strong,
rounded; foramen commonly open, but partially
closed by thin, disjunct deltidial plates in larger spec-
imens; surface smooth.

Ventral interior having pair of small, blunt hinge
teeth; edges of delthyrium supported by strong, ven-
trally slightly convergent dental plates; muscle attach-
ment areas posterior, elongate, poorly differentiated,
divided by low, broad median rise; valve floor between
dental plates thickened secondarily in larger speci-
mens.

Dorsal interior having low outer hinge plates; inner
hinge plates apparently disjunct in immature speci-
mens, in mature specimens conjunct, slightly raised
mesially and anteriorly, with small elongate apical per-
foration; outer socket ridges obsolete; inner socket
ridges high, thin, flared distally; hinge plate free of
valve floor; median septum absent; muscle attachment
areas elongate, poorly differentiated, separated by
low, indistinct median rise; loop long, cryptacanthi-
form, anteriorly bearing two or three sharp narrow
anteriorly-directed spines on each bout of junction be-
tween descending and ascending lamellae; descending
lamellae diverging slightly from bases, bearing dorsal
cuspate points, joined in young mature specimens by
posteromesially cuspate jugum, jugum apparently re-
sorbed in mature individuals; descending lamellae
closely appressed anteriorly near junction with as-
cending lamellae; ascending lamellae diverging dor-
soposteriorly, broadening, curving around to join as
slightly inclined broad transverse band at midline.

108

Measurements (in mm).—

Dorsal
Total Valve Maximum _ Thick-
Length Length Width ness
LOCALITY 6
(block A)
USNM 221541 1.8 1s) ied 0.9
USNM 221542 2.0 1.6 1.8 0.8
USNM 221543 2.3» 1.9 73511 1.0
USNM 221544 23s 2.0 2.0 1.0
USNM 221545 the 2.3 2.5 1.4
USNM 221546 2.8 23 2.6 1.5
USNM 221547 2.8» 2.4 2.6 1155)
USNM 221548 4.8 3}. 4.3 2.4
LOCALITY 6
(block C)
USNM 221549 4.1) 3.5 3.1 2.1
USNM 221550 4.8 4.1 4.0 2.5
USNM 221551 4.9 4.1 4.0 25
USNM 221552 6.5 5.6 Sk7/ 3.4
(holotype)

Occurrence.—Anaptychius minutus n. sp. is known
only from locality 6, blocks A, B and C of the Pal-
marito Formation. Based on other biostratigraphic in-
dicators, this horizon contains a fauna of latest Leo-
nardian to Early Guadalupian equivalent age.

Diagnosis.—Small Anaptychius.

Types.—Holotype: USNM 221552; Figured Speci-
mens: USNM 221550—221554; Measured Specimens:
USNM 221541-221552.

Comparison.—Anaptychius minutus is the only
species of the genus. It is differentiated from other
Cryptacanthiinae chiefly by its rectimarginate, unfold-
ed commissure and secondarily by its lack of a median
septum. Its small to minute size suggests that it may
be a small species of the genus.

Discussion.—Externally Anaptychius minutus is
very similar to such forms as Dielasmella Weller
(1911), a Mississippian cryptonellid. Internally, how-
ever, its hinge and loop clearly demonstrate its cryp-
tacanthine affiliation.

Material.—
Articu-
lated Dorsal Ventral Type of
Locality Valves Valves Valves Preservation
6 (block A) 18 6 5 fine silicification
6 (block B) 2 4 4 fine silicification
6 (block C) 17 4 3 fine silicification

Subfamily CRYPTONELLINAE Thomson, 1926
Genus TEXARINA Cooper and Grant, 1970

Type Species.—Texasia oblongata Cooper and
Grant, 1969, p. 17, pl. 5, figs. 7-9.

BULLETIN 313

Diagnosis.—Elongate, slender sulciplicate Crypto-
nellacea.

Occurrence.—Texarina has to date been reported
only from the West Texas region, in rocks ranging in
age from Leonardian (Cathedral Mountain and Road
Canyon Formations) to Guadalupian (Cherry Canyon
and Word Formations). An exact external homeo-
morph, Mimaria Cooper and Grant (1976b) (Hetere-
lasminidae) is known from the Sosio Formation of Sic-
ily. It differs from Texarina in having a short loop, no
dental plates and no hinge plate.

Comparison.—Texarina may be distinguished from
Cryptonella Hall (1861), in anterior view, by its more
broadly triangular outline, which is somewhat concave
ventrally, in contrast to the narrow transverse-ellipti-
cal outline characteristic of Cryptonella. The ventral
valve of Cryptonella is rarely so strongly sulcate as
that of Texarina. Heterelasma Girty (1909) and Tex-
arina are very similar. The beak of Heterelasma tends
to be more incurved, and the anterior folding is com-
monly better expressed in Texarina, though it is pres-
ent as well in Heterelasma.

Discussion.—The rare Palmarito specimens are as-
signed tentatively to the genus Texarina not so much
on the basis of their generic characters, but rather be-
cause they are most similar to a species of Texarina.

Texarina? cf. T. wordensis (R. E. King)
Plate 10, figures 18-29

cf. Dielasma problematicum wordense R. E. King, 1931, p. 131, pl.
44, figs. 16a-e.

cf. Texarina wordensis (R. E. King), Cooper and Grant, 1976b, p.
2836, pl. 771, figs. 1, 2; pl. 773, figs. 21-42; pl. 774, figs. 1-56; pl.
775, figs. 55-60.

Description.—Medium-sized, about average-sized
for genus, longer than wide; subtrigonal to elongate
rhomboid in outline, becoming more elongate through
ontogeny; greatest width variable, but commonly in
anterior third of shell in young, near midlength in ma-
ture individuals; sides broadly rounded at maximum
width; anterior margin narrow, only slightly truncated
in lateral view. Anterior commissure broadly unipli-
cate in young, sharply sulciplicate in adult shells. Sur-
face smooth except for anterior shell flexures.

Ventral valve broadly convex in lateral view, great- —

est convexity posterior; anterior profile moderately to
deeply concave, with sides elevated and narrowly
rounded, forming short, steep slopes. Beak suberect
to erect, beak ridges sharp; foramen small. Umbonal

region moderately convex. Sulcus very low, arising on |

anterior slope of umbonal region, broadening ante-
riorly. Anterior commissure emarginate, sulcus there
bearing low costa in adults.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 109

Dorsal valve of adults evenly, gently convex in lat-
eral view, more convex posteriorly in immature spec-
imens; in anterior view narrowly domed and with a
subcarinate keel; lateral slopes steep. Median region
broadly keeled from umbo nearly to anterior margin,
where shallow median sulcus developed, sulcus
bounded by strong rounded costae.

Interiors unknown.

Measurements (in mm).—

Dorsal
Total Valve Maximum Thick-
Length Length Width ness
Locatirty 11
USNM 221555 9.6, 8.6 7.0 4.6
USNM 221556 20.0 18.5 10.8 9.5

Occurrence.—Texarina wordensis occurs in the Ca-
thedral Mountain and Road Canyon Formations of
West Texas. In the Palmarito Formation the speci-
mens tentatively referred to the species have been re-
covered only from locality 11, where they are a rare
faunal element. A Late Leonardian age, based on this
occurrence, is not inconsistent with other biostrati-
graphic indicators in assemblage 11.

Diagnosis.—Narrow, moderately thick Texarina
having subtruncate anterior margin and subcarinate
dorsal valve.

Types.—Figured and Measured Specimens: USNM
221555—221556.

Comparison.—Texarina wordensis may easily be
distinguished from T. oblongata (Cooper and Grant,
1969) by the larger size of mature individuals of that
species, and from 7. paucula Cooper and Grant
(1976b) and T. solita Cooper and Grant (1976b) by the
smaller size of mature individuals of those species. T.
elongata Cooper and Grant (1976b) is much deeper
and in lateral view has a distinctly truncate anterior
margin. 7. parallela Cooper and Grant (1976b) shares
these characteristics with T. elongata, but has nearly
parallel sides that do not narrow appreciably anterior-
ly. In anterior view, the Palmarito specimens differ
from T. wordensis in their somewhat narrower outline
and less marked ventral sulcus.

Discussion.—The Palmarito specimens are tenta-
tively assigned to Texarina since they more closely
resemble a species of that genus than species of other
elongate sulciplicate terebratulid genera. Comparisons
are made to the West Texas form Texarina, rather
than its external homeomorph Mimaria Cooper and
Grant (1976b), since the latter is geographically far
distant from Venezuela, lessening the probability that
it and the Palmarito specimens could be closely relat-
ed.

Material.—
Articu-
Local- lated Dorsal Ventral Type of
ity Valves Valves Valves Preservation
11 4 1 — fine silicification
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tice of New Generic Characters involved in Two Species
of Brachiopoda. Chicago Acad. Sci., Trans., vol. 1, pp.
115-127.

Williams, A.

1953. The Morphology and Classification of the Oldhaminid
Brachiopods. Washington Acad. Sci., J., vol. 43, No. 9,
pp. 279-287, 3 pls.

Williams, A., Rowell, A. J., Muir-Wood, H. M., Pitrat, C. W.,
Schmidt, H., Stehli, F. G., Ager, D. V., Wright, A. D., Elliott, G.
F., Amsden, T. W., Rudwick, M. J. S., Hatai, K., Biernat, G.,
McLaren, D. J., Boucot, A. J., Johnson, J. G., Staton, R. D., Grant,
R. E., and Jope, H. M.

1965. Part H, Brachiopoda, in Treatise on Invertebrate Paleon- —
tology (R. C. Moore, ed.). Geol. Soc. Am. and Kansas —
Univ. Press, 2 vols., xxxii + 927 pp., 746 figs.

Williams, J. S. i
1943. Stratigraphy and Fauna of the Louisiana Limestone of
Missouri. U.S. Geol. Suryv., Prof. Paper 203, 133 pp., 9”

pls.

Yancey, T. E. i
1978. Brachiopods and Molluscs of the Lower Permian Arcturus |
Group, Nevada and Utah. Part 1: Brachiopods, Scaph- i
opods, Rostroconchs, and Bivalves. Bull. Am. Paleontol.,
vol. 74, No. 303, pp. 253-367, pls. 1-10, 6 text-figs.

Yochelson, E. L. |
1960. Bellerophontacea and Patellacea, in Permian Gastropoda |
of the southwestern United States, with notes on Penn-
sylvanian Bellerophonts. Am. Mus. Nat. Hist., Bull., vol.
119, art. 4, pt. 3, pp. 207-294.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER

PLATES

117

118

Figure
1-6.

10-16.

17-28.

30-36.

BULLETIN 313

EXPLANATION OF PLATE |

Petrocraniaiteretis! Coopervamd (Grantee. teciayercto ntfs te ode cose ser es = septs. vaya nvevctovedeyebetatoteneueyeis ietenereravorale che eyelevey=toietel-vof- eee ree eee 39
1-5. Dorsal valve, USNM 220975; 1. exterior view, x1; 2. interior view, x1; 3. exterior view showing smooth exterior
surface, x5; 4. interior view, showing well-impressed muscle scars, x5; 5. lateral view, showing asymmetrical profile,
4; locality 6 (block A).
6. Articulated valves, USNM 220979. ventral view, showing valve overlap, x4; locality 6 (block A).

AN GOSAN UMN? 'S Ps Oe eye fake lovee care feeah spate Suey serena cere er sis 270.0) clapeue¥elteve/ ates opere fepeyVeNc) RES eae eck ot = Vateh Pie ieks gale oteke thee kee aa eee 40

Ventral valve, USNM 220981; 7. interior view, showing development of dental plates and median septum, <1; 8. same view,

showing disposition of teeth, x2; 9. posterior view, showing narrow delthyrium and small triangular teeth, x2; locality 7.

Derbyia civ DsicomplicataiGCooperiand Grants cyege oteyesesatoter 10/21 ose = cavaveveieteceretatere re) ole as=eletarererore vey sled sey tare afetalegayev ate) ole= toe tetee ee ete aa 43

10-12. Articulated valves, USNM 220988; 10. posterior view, showing low dorsal interarea and well-developed chilidium,
x1; 11. dorsal view, showing distinct sulcus and characteristic surface ornament of alternating crenulate costae and
costellae, x1; 12. ventral view, showing low fold and characteristic surface ornament, 1; locality 8.

13-15. Single dorsal valve, USNM 220986; 13. ventral (interior) view, showing broadly divergent erismata, shallowly bifurcate
cardinal process myophore and internal reflection of exterior surface ornament, x1; 14. posteroventral (interior) view,
showing relation of cardinal process to hingeline and development of hinge sockets, x1; 15. posterior view, showing
development of chilidium, 2; locality 4.

16. Fragment of ventral valve, USNM 220987; interior view, showing short median septum, faintly impressed muscle
attachment scars, and interior reflection of exterior surface ornament, x2; locality 8.

Derbyia/deltauriculataimi:Sps | 2f5s)< 5 seers w:cicscctercteteve setts etese se seca oveysusisle ye eyo) obelole euaye ese siete eyo eletels stata e)e eee 44

17-19. Single dorsal valve, USNM 220991; 17. ventral (interior) view, showing moderately well-impressed adductor muscle
attachment scars, distally sinuous erismata, and large deltoid ears, x1; 18. posteroventral (interior) view, showing
relation of cardinal process to hingeline, and development of hinge sockets, x1; 19. posterior view, showing swollen
valve and development of chilidium, x1; locality 10.

20. Dorsal valve, USNM 220990; dorsal view, showing large deltoid ears, characteristic subdued surface ornament and
low cardinal process, x1; locality 10.

21-22. Articulated valves, USNM 220994; 21. posterodorsolateral view, showing relation between the two valves, x1; 22.
ventral view, showing horn coral (possible symbiont) attached to ventral valve, in position to intercept inferred in-
current flow (lateral portion obscured by photographic mounting medium), x1; locality 10.

23. Ventral valve, USNM 220995; dorsal (interior) view, showing deflection of anterior margin and asymmetric interarea,
produced by growth in crowded conditions, x1; locality 10.

24. Ventral valve, USNM 220996; posterior view, showing asymmetry produced by growth in crowded conditions, x1;
locality 10.

25-26. Ventral valve, USNM 220989; 25. posterior view, showing actual size, <1; 26. posterior view, showing low interarea
and mesially grooved pseudodeltidium, x2; locality 10.

27-28. Single ventral valve, USNM 220993 (holotype); 27. dorsal (interior) view, showing long median septum and well-
impressed adductor muscle attachment scars, <1; 28. ventral view, showing large deltoid ears and characteristic
subdued surface ornament, x1; locality 10.

Derby iia pee tarecacc ices atesesstein te teucvee cre em catauch c e0Sed este ace ol asin av ge aa) Olas Pye an beats nanlenetofat chet eter oneaete opete ein at nests saree on 46

Portion of ventral valve, USNM 221002; ventral (exterior) view, showing characteristic surface ornament, x3; locality 6

(block C)

Derbyiatauriplexasn. Sp. cccsve:eisse1o.2chcyod= sevens Ve aves he seh och eve ceifev ofa soledes ol sVee deteuetoheushel ol Selere oa ploneteterenelatctexeraterets fst) stet-eaee Te ee ee 42

30. Fragmentary ventral valve, USNM 220984; interior view, showing internal reflection of exterior ornament, adductor
muscle scars and marginal setal grooves, <1; locality 13.

31-34. Single dorsal valve, USNM 220983; 31. posteroventrolateral view, showing cardinal process, socket development and
auriculation of hinge (anterolateral portion of valve obscured by photographic mounting medium), <1; 32. posterior
view, showing valve profile and relation of cardinal process myophore to erismata, x1; 33. ventral view, showing
adductor muscle marks, erismata, dentifers, and strongly cleft cardinal process myophore, <1; 34. exterior view, show-
ing irregular surface ornament and auriculation of hinge, <1; locality 13.

35-36. Articulated valves, USNM 220982 (holotype); 35. anterior (interior) view, showing juxtaposition of cardinal process
and dental ridges (dorsal side down), * 1.5; 36. posterior view, showing ungrooved pseudodeltidium and distinct dorsal
sulcus, *1.5; locality 13.

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE |

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 2

Figure

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 119

EXPLANATION OF PLATE 2

iO, Deity Gs.WDs fits Coogee andl Grint sossooascsnnonseno0 pboooUoUMooUDOUHoDuCdooNnabcoodGHoodboDHaDoDUSDHDSouoeoSood0S

1-2.

ies)

Apical fragment of large dorsal valve, USNM 221001; 1. posterior view, showing development of hinge sockets and
relationship of cardinal process to hinge, <1; 2. ventral (interior) view, showing development of erismata and dentifers,
deeply cleft cardinal process myophore, and faintly striate adductor muscle attachment scars, <1; locality 11.

Apical portion of ventral valve, USNM 220999; anteroventral view, showing the paired fossae located at the junction
of median septum and dental ridges, < 1.5; locality 11.

Articulated valves, USNM 221000; 4. posterior view, showing relationship between dorsal valve and ventral interarea,
x1; 5. anterior (interior) view, showing relationship of juxtaposed cardinal process and dental ridges, x1; locality 11.
Partial ventral valve, USNM 220998; ventral view, showing large size, fine ornament of costellae, and the irregular
bumpy texture characteristic of larger valves, 1; locality 11.

etm VICCKENAiSK MOINES! GT, | ve fete isis evel cvsv eve) orsecete 1619 Syeye1 6 6 ele cep creer o1OIeySueneteh e tayersici@) elevsyaleie « sreifeese)s) eiestschsteuel cele) o cusiels) <)etvowi stelle eheisi evmrereselesfevedove

7-9.
10.

2
13-15.

16.

Three sets of articulated valves, USNM 221003, USNM 221004, and USNM 221005; posterodorsolateral views of
simulated partial ontogenetic series, showing differential growth of the two valves, all x1; locality 3.

Ventral valve, USNM 221011; dorsal (interior) view, showing relationship of teeth, dental ridges and dental plates,
and internal fold corresponding to pseudodeltidial monticulus, 1.5; locality 3.

Partial ventral valve, USNM 221008; posterior view, showing pseudodeltidium bearing monticulus, and sharp teeth,
2; locality 3.

Dorsal valve, USNM 221007; dorsal (exterior) view, showing costae superposed on fine costellae, x1; locality 4.

Single dorsal valve, USNM 221010; 13. ventral (interior) view, showing long cardinal process and dentifers, and com-
paratively short erismata, x2; 14. posterior view, dorsal side down, showing broad dentifers, elongate, longitudinally-
slit myophore with shallow median cleft and apparent lack of chilidium, x2; 15. posteroventrolateral view, showing
development of cardinal process and dentifers, and relationship of hinge socket to hinge, 2; locality 3.

Articulated valves, USNM 221009; anterior (interior) view, showing juxtaposition of cardinal process and dental plates,
x2; locality 3.

INE) OMY OLOSTACANICHOPELIXGINES Dancap rer acrerey aie sheerreyeve oh ve esses ssuel eT areyey syed ave anal ty chedan ses vey tepaver axe topsteaneueaeredeney oe irae Zoueetien en cdevopee lel ievens ses) mhahscetene toredee

17-20.

21-22.

Four sets of articulated valves, USNM 221012, USNM 221019, USNM 221025 (holotype), and USNM 221031; ventral
views, showing range of variation in size and outline of a simulated partial ontogenetic series, all <1 (photographed
in transmitted light, immersed in glycerine); locality 2.

Two sets of articulated valves, USNM 221025 (holotype) and USNM 221031; 21. ventral (exterior) view, showing
smaller, somewhat inset dorsal valve and oblique spine bases along hingeline; 22. ventral (exterior) view, showing
shadows of endospines on tips of anderidia and anterior end of median septum, as well as anterior endospinose fringe,
both x2; locality 2.

Dorsal valve, USNM 221035; ventral (interior) view, showing comparatively insignificant development of anderidia and
anterior endospinose fringes in an inferred early ontogenetic stage, <2; locality 2.

Fragmental ventral valve, USNM 221034; dorsal (interior) view, showing anteriorly endospinose median septum and
large endospines fringing the adductor muscle attachment areas, <2; locality 2.

Articulated valves, USNM 221026; posterior (exterior) view, showing hood-like crescentic pseudodeltidium and multi-
lobate cardinal process, x2; locality 2.

Partial dorsal valve, USNM 221033; ventral (interior) view, showing long median septum, short lateral septa, strong,
anteriorly endospinose anderidia and anterolateral endospinose fringes, <2; locality 2.

oo? Chonetinetes cf... varians Cooper and Grant cc i5- 20s cw cies ce bloc cic ee visitie » s visiel sisi esis winvele Gitiq cles sees 6s) ae Weise eine aiwies«

27-30.

33-34.

35-36.

37.

Articulated valves, USNM 221048; 27. dorsal (exterior) view, showing size and outline of typical shell, x1; 28. same
view, showing radial ornament, hinge spine bases and surficial pits, x2; 29. ventral (exterior) view, showing radial
ornament, surficial pits and lack of a distinct median sulcus, x2; 30. anterior view, showing lack of a distinct median
fold or sulcus, x2; locality 8.

Dorsal valve, USNM 221056; ventral (interior) view, showing long, anteriorly endospinose median septum, anteriorly
endospinose anderidia and radial rows of minute endospines, x2; locality 8.

Ventral valve, USNM 221051; dorsal (interior) view, showing comparatively large teeth, long median septum and
interior endospines, <2; locality 8.

eo mOtauromata,eSOterican PENANG SP: cise ar. cageys an crewsncne) sce Gyateibis wih cferniee micave tow slew are ene eyarerere he eeeeatevel Me eMe ene esi eh eke ele sla aha evesenerele ©

Articulated valves, USNM 221040 (holotype); 33. ventral view, showing valve outline and surface ornament, x1;
34. dorsal view, showing size and outline of shell, x1; locality 7.

Articulated valves, USNM 221039. 35. lateral view, showing sinuous curvature of commissure; 36. posterior view, show-
ing interareas with hood-like crescentic pseudodeltidium and multilobate cardinal process myophore; both x2; locality 7.
Apical portion of dorsal valve, USNM 221043; ventral (interior) view, showing bases of lateral septa, anderidia and
median septum, and apparent dendritic adductor muscle attachment scars, x2; locality 7.

120

Figure
1—25-

Stauromata esoterica n. gen. and sp.

BULLETIN 313

EXPLANATION OF PLATE 3

1-20. Serial peels of a single set of articulated valves, USNM 221045; sections parallel to plane of commissure, x2;

21-25.

locality 7.

Distance between successive peels as follows:
1-2 0.10 mm
2-3 0.20 mm
344 0.15 mm
4-5 0.15 mm
5-6 0.15 mm
6-7 0.15 mm
7-8 0.15 mm
8-9 0.15 mm
9-10 0.10 mm

10-11
11-12
12-13
13-14
14-15
15-16
16-17
17-18
18-19
19-20

0.20 mm
0.15 mm
0.15 mm
0.15 mm
0.15 mm
0.15 mm
0.45 mm
0.15 mm
0.45 mm
0.15 mm

Schematic reconstructions (as stereopairs) of separated valves of USNM 221045, based on projections of the peels;

all «4.

21-22. Dorsal valve interior, seen from within, showing the prominent endospinose median ridge, anterior endospinose

fringes and distally spinose anderidia.

22-23. Dorsal valve interior, seen through the [transparent] valve from the exterior, showing the relationship of the

distal ends of the anderidia and the anteriorly placed ventral valve endospinose palisades (arrow).
24-25. Ventral valve interior, showing the position of the endospinose palisades (cf. Pl. 4, figs. 1, 2).

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 3

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 4

Figure
iA

3-18.

19-37.

38-39.

40-45.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 121

EXPLANATION OF PLATE 4

Page
Stauromata esotericarn agen canGeSp!,. .<Ppereteper epee ore ot cneves os <i isretstars ye ecenews terete) oles ay aie "ahway ov acetaveusts’ syoyarsve.areuovays avscs a eye csnavsualeve.edere mereuyereisas D2
1. Ventral valve fragment, USNM 221044; dorsal view, showing low ventral median septum, apparently dendritic ad-
ductor muscle attachment scars and coarse endospinose palisades, x2; locality 8.
2. Ventral valve, USNM 221036; dorsal view, showing bases of hinge spines, narrow median ridge and prominent, in-
ternally striate endospinose palisades, <2; locality 4.
XEnOSteSesy MINUSCHIUSSIIESD meer Teeter secrietiae tee tierra: sie cieiereistereeieierieiciel ieisraic ciciterds crriariciacieiamiciicreeaa

3-6. Four sets of articulated valves, USNM 221057, USNM 221058, USNM 221059, and USNM 221062 (holotype); dorsal
views, showing the size range of a simulated partial ontogenetic series, all «1; locality 6.

7-9. Articulated valves, USNM 221062 (holotype); 7. dorsal view, showing smaller dorsal valve inset into larger, distally
flanged ventral valve; 8. ventral view, showing lamellose ornament and lack of ornament spines; 9. anterodorsal view,
showing smoothly curved commissure; all <4; locality 6.

10-14. Five dorsal valves, USNM 221063, USNM 221064, USNM 221065, USNM 221066, and USNM 221067; ventral (interior)
views, showing progressive development, in simulated partial ontogenetic series, of cardinal process, median septum,
brachial ridges, adductor muscle scars, submarginal ridges, and endospines, all x4; locality 6.

15. Dorsal valve, USNM 221068; ventral (interior) view, showing presence of ontogenetically ‘‘mature’’ characters (ex-
pression of muscle scars, brachial ridges) in small specimen, x4; locality 6.

16. Ventral valve, USNM 221069; dorsal view, showing interarea and lightly impressed diductor scars, <4; locality 6.

17. Ventral valve, USNM 221070; dorsal view, showing asymmetric form, marginal flange and interarea, <4; locality 6.

18. Three ventral valves (cemented together), USNM 221071; dorsal view, showing commonly observed apparent life habit,
attached to sponge, x4; locality 6.

CooperinajinexpectatalLermierermierand) Pajaud) icteric sees ee ie casi ionic eleietelei ee eisiceie siete melee escuela le eiiiereleeie = 57

19. Dorsal valve, USNM 221117; ventral view, showing size of small individual of the species, x1; locality 6.

20-24. Five dorsal valves, USNM 221117, USNM 221118, USNM 221084, USNM 221121, and USNM 221132; ventral (interior)

views, showing progressive development of median and submarginal ridges in forms similar to C. parva Cooper and

Grant (1975), x4; locality 6.

Ventral valve, USNM 221144; dorsal (interior) view, showing a small apparent juvenile ontogenetic stage, x4;

locality 6.

26-27. Ventral valve, USNM 221143: 26. dorsal (interior) view, umbo down, showing distal flange and median ridge; 27.
dorsal view, umbo up, showing flat interarea, anterior portion of median ridge, and some ornament spines; both x4;
locality 6.

28. Dorsal valve, USNM 221145; ventral (interior) view, showing the low median ridge and comparatively flat valve of an
apparent young individual, x4; locality 6.

29. Dorsal valve, USNM 221146; ventral (interior) view, showing the high median ridge and curved valve of an apparently
mature individual, x4; locality 6.

30-35. Five dorsal valves, USNM 221092, USNM 221086, USNM 221112, USNM 221104, and USNM 221142; 30-34. ventral
views, showing the range of shape variation observed in Palmarito specimens, all x4; (negative reversed on fig. 31,
USNM 221086); 35. USNM 221142, ventral (interior) view, showing massive quadrilobate cardinal process, deeply set
adductor muscle platforms, strong median and submarginal ridges, and the distally serrate brachial ridges, all indicative
of a gerontic ontogenetic stage, x8; all from locality 6.

36. Articulated valves, USNM 221075; posterodorsolateral view, showing attachment to bryozoan by basal circlet of rhizoid
spines, <8; locality 6.

37. Articulated valves, USNM 221079; anterodorsal view, showing the juxtaposition of dorsal and ventral valves when the
shell is gaping, <8; locality 6.

Rhammariidae’chy Rama veces ssp sty s ers etre lotste ois to es wine Tore eie tea ceebe hie Seve STREET ere ree eee eee een eae tate 59

38. Fragmental articulated valves, USNM 221147; dorsal view, showing low apparent interarea, impression of long narrow
median septum and impressions of numerous endospines, x1; locality 11.

39. Dorsolateral view of specimen shown in Plate 4, figure 38, taken during acid etching (spines later lost); dorsolateral
view, showing the slender ear spines, approx. x0.6; locality 11.

Echinaurisibellaj CooperandtGrantyes jcc c sce Re STee sce cists nso he vata ere ors aor Seale aes cele uote eka touse et venetaters eiciere ie euegnmeves 62

40-42. Three ventral valves, USNM 221175, USNM 221176, and USNM 221177; ventral views, showing simulated partial
ontogenetic series, <1; locality 13.

43-47. Single ventral valve, USNM 221177; 43. ventral view, showing brush of anterior ornament spines and comparatively
bald umbo; 44. dorsal view, showing low, non-swollen umbo and equidimensional shape of the shell; 45. lateral view,
showing the differing orientation of ear spines from those on the anterior slopes of the shell; 46. posterior view, showing
the low umbo, and differing orientation of ear and anterior slope spines; 47. anterior view, showing the extension of the
anterior slope spines well beyond the commissure; all 2; locality 13.

48-49. Single dorsal valve, USNM 221179; 48. dorsal (exterior) view, showing small cardinal process, centripetally directed
spines and dimpled ornament; 49. ventral (interior) view, showing marginal ridges, fragile ear, short median septum,
muscle scars, and development of endospines, x2; locality 13.

50-51. Dorsal valve, USNM 221178; 50. posterior (interior) view, showing quadrilobate cardinal process, muscle attachment
scars and low bladelike median septum; 51. ventral (interior) view, showing cardinal process, muscle scars, marginal
ridges, median septum and brachial ridges; both x2; locality 13.

52. Partial ventral valve, USNM 221182; anteroventrolateral view, showing differing orientation of lateral (ear) and anterior
slope spines, <2; locality 13.

53. Ventral valve fragment, USNM 221173; anterolateral view, showing the great extent to which the anteriormost ventral
spines overreach the commissure, x2; locality 13.

54. Partial ventral valve, USNM 221183; dorsal (interior) view, showing paired, elongate, inset adductor scars, <2; locality 13.

55. Group of articulated and disarticulated specimens, USNM 221174; photograph taken during acid etching process,
showing the fine preservation that indicates this to have been a living position, despite the apparent random orienta-
tion of the shells, x1; locality 13.

ind
tn

122

Figure

1-2

13-19.

33-42.

43-45.

46.

BULLETIN 313

EXPLANATION OF PLATE 5

Echinauris' bella' Cooper and Grants oo\0.0'9 rexsts.siers, = ecave toseuoxehexe eu sysy ev loyeueyo (ave ose suse (Rca, Suan bliauwt 6 (e)enepeste oi oneyeneaenet Mayate kee eT eke eee eee 62

1. Dorsal valve, USNM 221180; ventrolateral view, showing a slightly more robust development of the median septum than
that shown in Plate 4, figure 49, x2; locality 13.

2. Dorsal valve, USNM 221181; posteroventral (interior) view, showing the heavy marginal ridges, muscle scars on plat-
forms, and distally expanded median septum of an apparent gerontic specimen, x2; locality 13.

Echinauris cf-.E;lappacea‘Cooper, and): Grant: «2... .. sjeysj-s2 Scyeyetereie eieteseye ayers steve pesuckersie vere eiessickeere ate eyete = fetatsiel eee iota eet 64

3. Articulated valves, USNM 221185; dorsal (exterior) view, showing thick, centripetally-directed dorsal ear spines, small,
protruding umbo, and transverse profile, x 1.5; locality 11.

4. Articulated valves, USNM 221192; posterodorsolateral view, showing extremely transverse individual, x 1.5; locality 11.

5. Articulated valves, USNM 221193; posterodorsolateral view, showing globose individual, x 1.5; locality 11.

8. Dorsal valve, USNM 221191; 6. dorsal (exterior) view, showing dimpled surface, fragile ear, and quadrilobate cardinal
process; 7. ventral (interior) view, showing prominent muscle scars and long median septum; 8. posterior view, showing
omega-shaped cardinal process myophore and elevated muscle scar platforms; all x1.5; locality 11.

9-12. Articulated valves, USNM 221188; 9. dorsal view, showing bases of dense brush of centripetally-directed ear spines,
low umbo and transverse outline; 10. posterodorsolateral view, showing shape of shell; 11. anterior view, showing slight
ventral sulcus, extremely faint radial ornament, and bases of scattered spines; 12. ventral view, showing low umbo,
transverse outline, and arrangement of sparsely scattered spines; all x1.5; locality 11.

Echinauris:cf. E. liumbona. Cooper and Grant -0.5)6.<.0)< djs ciee 206 « <3 aye ates lstt alspejsisiaiaisys aleiefiserece, es sale seleicle oper a anser eels eee ee eee eee 65

13-17. Associated valves, USNM 221213; 13-15. ventral valve; 13. lateral view, showing arrangement of lateral spines, low
umbo and lateral outline, x1; 14. anterior view, showing anterior profile and apical interior, x1.5; 15. posterior view,
showing low, denuded umbo and hinge spine disposition, x1; 16-17. dorsal valve; 16. dorsal (exterior) view, showing
partially silicified omega-shaped cardinal process, and lack of zygidium, <1; 17. posterior view, showing form of
cardinal process, <4; locality 4.

18. Articulated valves, USNM 221203; dorsal view of negative impression (internal cast) of decorticated dorsal valve,
showing bipartite muscle scars, omega-shaped cardinal process myophore, extent of narrow median septum and develop-
ment of strong anterior endospines, 1.5; locality 8.

19. Articulated valves, USNM 221204; posterior view, showing length of trail, posterior profile, low umbo and a few remain-
ing dorsal exterior ornament spines, x 1.5; locality 8.

Anemonaria‘sublaevis.(R. Es King): sic. efor cia cave vie ie 0 Gis i chere avert 0 5 loco ve le en ever Alle) os eration ole esOTENG ST Spy SY SEROTEC TSEC TTA Sec SE 67

20. Ventral valve, USNM 221217; anterodorsal view, showing slight ginglymus in ventral apex, which accommodates
dorsal zygidium, 1; locality 10.
21-23. Ventral valve (broken and repaired), USNM 221218; 21. ventral view, showing faint low radial ornament and single row
of spines along break in slope between body of shell and ears, x1; 22. dorsal (interior) view, showing crenulate ear
baffle, smooth interior and slight sulcus, x1; 23. ventrolateral view, showing disposition of spine row, x1.5; locality 10.
24-25. Fragmental dorsal valve, USNM 221216; 24. dorsal (exterior) view, showing fine radial ornament, dorsally-facing cardinal
process myophore, and small, but prominent zygidium, x1; 25. ventral (interior) view, showing complete submarginal
ridge, crenulate across ears, muscle scars, and small, prominent zygidium, x1; locality 10.
26-27. Two fragmental dorsal valves, USNM 221219 and USNM 221220; posterior views, showing forms of cardinal process
myophore, both x2; locality 10.

Anemonaria? cf; A. sublaevis:(R. EF. Kang)! oc... ese. c.< ej sseseseteseievsie ssebe je ail ef etoile) = eve!s) eVe 01s ete eels je aietededouehe):teheas «\s) fet oie et eet eae 68

Ventral valve, USNM 221221; ventral view, showing subdued radial ornament, disposition of spine row and mesial sulcus, x1;
locality 1.

Paucispinifera? cf. |P:isuleata Cooper amdGrant ool eee ce wee ted el hese) l= aisle) 1= «) svete) =yois © =) eyereleyslolt slay auels}= ole ysiel=ieneteteneteeele eter retaiete 69

29. Articulated valves, USNM 221222; dorsal view, showing partially decorticated dorsal valve and form and disposition
of cardinal process myophore, muscle scars, median septum, brachial ridges and endospines, and suggesting the pres-
ence of a strong zygidium filling the ventral apex, x1; locality 8.
30-32. Articulated valves, USNM 221223; 30. anterior view, showing prominent radial ornament bordering prominent sulcus,
and anterior profile, <1; 31. posterolateral view, showing disposition of spine row, x1; 32. dorsal view, showing
aspinose, radially ornamented dorsal valve, moderately deep umbo, and recurved ears, x1; locality 8.

Holotricharina hirsuta Cooper and Grant jos.e.6.ossj0 6.005 6.65 0:6 wiertid ele eis g loye sieie ose) noses ar evereloua joys ers layo)0 Seka Lecce fe/elaiteke ie ee rn eee 70

33-35. Three ventral valves, USNM 221225, USNM 221228 and USNM 221227; ventral views, showing form and disposition
of ventral spines, concentric ornament, and range of form and shape encountered; all <1; locality 4.

36-37. Ventral valve, USNM 221228; 36. anterodorsal (interior) view, showing radiating ridged muscle attachment scars,
1.5; 37. dorsal (interior) view, showing arrangement of spines on hinge and ears, and muscle scars, x 1.5; locality 4.

38-39. Articulated valves, USNM 221232; 38. ventral view, umbonally excavated, showing apical portion of partially silicified
dorsal valve interior, x 1.5; 39. dorsal view of largely decorticated dorsal valve, showing long, slender median septum,
1.5; locality 8.

40-42. Articulated valves, USNM 221230; 40. dorsal view, showing concave dorsal valve and characteristic irregular con-
centric ornament, x1.5; 41. lateral view, showing outline, x 1.5; 42. posterior view, showing low umbo, wrinkled ears,
and lack of prominent ventral sulcus, x 1.5; locality 8.

Holotricharima?: Spi A. sss isis sistent cevoreseteieney sivas’ 6; te.ot af rese (oy oeeteteteuctee sya /afeceioyai ois laueneley stele hated seetteneLele wenstavere ateae earerore Pep eiclaeere reer een ieee 71

Single, fragmental, dorsoventrally-crushed ventral valve, USNM 221233; 43. dorsal view, showing swollen umbo, spine arrange-

ment and somewhat flanged margin; 44. ventral view, showing spine arrangement and apical interior; 45. lateral view, showing

profile and form and disposition of ornament spines; all <1; locality 13.

Echinoconchidae, genus indeterminate. ./....<:5:<ascestss ocssslerele. cvste cose vlebateysyesvevai sueseytefe 07 ouctete(akelshes meleperetrte ie take yeloses i cietereNeten teeter 74

Fragmental interior of articulated valves, USNM 221240; ventral (interior) view, showing impression of pointed ventral umbo

and most of dorsal interior, with impression of lateral ridges, apparently bipartite median septum and endospines in rough

concentric pattern apparently mirroring inferred external concentric banding, x1; Field No. Ar-981 (Arnold coll.).

| BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 5

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 6

21-28.

| 29-35.

Figure
1-10. Kutorginella cf. K. umbonata (Muir-Wood and Cooper) .............. 00 eee cece cece eee cence cece ueeeeeeeeeeeees

1-2.

2).
10.

11-14.

Rugatia
21-23.

Rugatia
29.

30-32.

83°

34-35.

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 123

EXPLANATION OF PLATE 6

Fragmental articulated valves, USNM 221237; 1. dorsal view, showing shell outline and geniculation, development of
fold and sulcus, thin trail, dorsal exterior ornament and dorsal aspect of cardinal process myophore; 2. lateral view,
showing lateral profile; both x1; locality 8.

Fragmental ventral valve, USNM 221234; 3. posterodorsal (interior) view, showing distinct ventral sulcus, muscle
scars and sharply recurved ear; 4. anterior (interior) view, showing apically constricted median ridge flanked by diductor
scars, and anteromesial dendritic muscle scars on slight platform, as well as sharply demarcated ears; both 1; locality 4.
Fragmental articulated valves, USNM 221235; 5. dorsal view, showing dorsal exterior reticulate ornament; 6. poste-
rior view, showing ventral exterior reticulation; both x1; locality 4.

Fragmental dorsal valve and associated external mold, USNM 221236; 7. posterior view, ventral side up, showing form
of myophore of cardinal process, <2; 8. anteroventrolateral (interior) view, showing anteriorly constricted median
septum, dendritic adductor muscle scars, strongly reticulate visceral disc, strong ridge across ears, and abrupt sub-
marginal geniculation, x1; locality 8.

Fragmental articulated valves, USNM 221239; dorsal view, showing form of cardinal process myophore; x1, locality 8.
Dorsoventrally crushed ventral valve, USNM 221238; ventral view, showing sparsely spinose radial ornament, x1;
locality 1.

20: Peniculauris)subcostata latinamericana N: SSP: 3... <6 ..6 ese ee cence ce cess eee eae s ceeeeetiecieesccuisieeieceieveeecveness

Ventral valve, USNM 221244 (holotype); 11. ventral view, showing anteriorly narrowing costae and size and outline
of shell, x1; 12. ventral view, included for size comparison to following figures, x0.5; 13. anterior view, showing
repeated trails, low umbo and anterior profile, x0.5; 14. posterior view, showing prominent reticulation and brushes of
spines on ears, 0.5; locality 1.

Ventral valve, USNM 221245; lateral view, showing anteroposterior variation in surface ornamentation and lateral
profile, x0.5; locality 1.

Dorsal valve, USNM 221246; 16. posterior view, ventral side up, showing low median septum, prominent lateral
ridges and massive mesially recurved cardinal process myophore, x2; 17. ventral (interior) view, showing short-
shafted cardinal process, strong lateral ridges crossing ears and continuous around visceral disc as low step in shell
surface, long slender median septum, muscle scars, and concentric and endospinose ornament, x0.5; locality 1.
Crushed articulated valves, USNM 221247; dorsal view, showing poorly preserved reticulation of dorsal visceral disc,
x0.5; locality 1.

Partial ventral valve, USNM 221248; dorsal (interior) view, showing raised, dendritic adductor scars flanked by inset,
rounded, striate diductors, x0.5; locality 5.

Portion of ventral valve, USNM 221242: ventral view, showing concentric wrinkling on ear and form and disposition
of ornament spines, 1; locality 1.

niGuitihins Sob cies oacchy soto deceeO rN AAeeS ono nce DOD Oo omic” SoOnaC.ad COS Ree EOS Cn OOS ae ee tee. ae a
Fragmental dorsal valve and external mold, USNM 221250; 21. posterior view, dorsal side down, showing relationship
of cardinal process myophore to adductor muscle scars, x2; 22. ventral (interior) view, showing short lateral ridges,
raised dendritic adductor scars, subdued reticulation and moderate geniculation of the visceral disc, <1; 23. anterior
view, showing raised adductor scars, x1; locality 8.

Portion of ventral valve, USNM 221252; anterior (interior) view, showing poorly impressed diductor scars, adductor
scars on mesial platform, and slight apical ginglymus, <1.5; locality 8.

Articulated valves, USNM 221249 (holotype); 25. ventral view, showing coarse radial ornament and sparsely spinose
exterior of ventral valve; 26. dorsal view, showing form and ornament of dorsal valve and ventral umbo; 27. lateral
view, showing apparently secondarily compressed profile and coarse ornament; 28. posterolateral view, showing dispo-
sition and form of spines running along ears and variation in radial ornament; all x1; locality 11.

occidentalis! (INC WDEILY) Meir rsteset cetera tees ce ere eee acters eee ee Me eee Te ee ae See aoa ee Oe ener:
Crushed ventral valve, USNM 221254; ventral view, showing subdued coarse radial ornament and small spinose ears,
x1; locality 1.

Fragmental (repaired) dorsal valve, USNM 221257; 30. ventral (interior) view, showing shaft of cardinal process and
muscle scars, X1.5; 31. posterior view, showing mesially reflexed dictyoclostid cardinal process, x2; 32. dorsal view,
showing apparent trilobate aspect and rough surface of cardinal process and nearly smooth exterior surface, x2;
locality 1.

Portion of ventral valve, USNM 221253; posterior view, ventral side up, showing disposition of spines from umbo
toward lateral extremities, x1; locality 1.

Portion of ventral valve, USNM 221256; 34. anterior view, showing anterior profile, repeated trails, radial ornament
and spine disposition; 35. anteroventral view, ventral side up, showing subdued radial ornament and form and dis-
position of spines; both x1; locality 1.

124

Figure
1-10.

11-15.

16-23.

24-36.

37-38.

39-48.

BULLETIN 313

EXPLANATION OF PLATE 7

Spinifrons‘grandicosta sn Spsy yarejsis sis oreleo1-. <akaxe fais se) vreneletevstsleye yo) oh -eatatetoyavohehekels <1 aiehaue!abelsie’aic. ceeta eto baeater= heise trate las ietee tree ete taea
1-8. Articulated valves, USNM 221259 (holotype); 1. dorsal view, showing form, outline and size of the shell and the
dorsal exterior ornament, <1; 2. dorsal view, included for size comparison to following figures, x0.5; 3. lateral view,
showing anteroposterior change in surface ornament and lateral profile, 0.5; 4. ventral view, showing somewhat
irregular costation and sparsely distributed spines, x0.5; 5. anteroventrolateral view, ventral valve down, showing
relative valve forms, raised mesial dendritic ventral adductors and larger distal ventral diductor muscle scars, x0.5;
6. anteroventrolateral view, dorsal valve down, showing cardinal process, lateral ridges and median septum of dorsal
valve, x0.5; 7. posterior view, showing form and disposition of spines along hinge and on ears, and reticulate orna-
ment of ventral umbonal area, <0.5; 8. anterior view, showing low, small umbo, raised trail margins, recumbent ears
and repeated trails, x0.5; locality 13.
9. Portion of ventral valve, USNM 221258; ventral view, showing somewhat irregular broad costae and clusters of
spines laterally and anteromesially, <0.5; locality 13.
10. Fragmental ventral valve and external mold, USNM 221260; dorsal (interior) view, showing disposition of muscle
scars, X0.5; locality 8.

Spinifrons? (cf. S- srandicostayaeySPes cee leieiiege clelels ecko eldelareielelaleisoietaitatedolereieieleneielee aeielaieteletatelcieieeisioceielattistektels ete eee

11-13. Three fragmental, partially silicified dorsal valves, USNM 221266, USNM 221264, and USNM 221265; posterior views,
showing range of variation in form of the cardinal process myophore, all 2; locality 11.

14. Fragmental dorsal valve, USNM 221263; ventral (interior) view, showing accessory septa, x1; locality 4.

15. Fragmental articulated valves, USNM 221262; dorsal view, showing dorsal exterior ornament, 0.5; locality 11.
Collemataria’venezuelensisin= (Spi ieee =<) sv-kere sverslaicse eters <iauels eletotaie/e-o ofr o/ heteyatepelolcreteber oicterayeverc\eyate ota\ alec) 1 e)etekcns tenets tate Reece te Reeens enema
16-17. Ventral valve, USNM 221269 (holotype); 16. dorsal view, showing reflexed posterior attachment flap, beaded septa

and encrusting bryozoan; 17. ventral view, showing smooth to lamellose ventral exterior, and attachment cicatrix;
both x1; locality 6.

18-19. Dorsal valve, USNM 221272; 18. ventral (interior) view, showing truncated hinge margin, median ridge and endo-
spinose submarginal ridge; 19. dorsal (exterior) view, showing smooth rounded surface and median groove; both x2;
locality 6.

20. Dorsal valve, USNM 221274; ventral (interior) view, showing obliquely oriented bilobate cardinal process, x2;

locality 6.

1. Dorsal valve, USNM 221273; ventral (interior) view, showing submarginal ridge and anteromesial cleft, «2; locality 6.

2. Two fragmental ventral valves, USNM 221271; anterodorsal views, showing inset triangular hinge area and reflexed

attachment flap, x2; locality 6.

23. Incompletely etched block with two ventral valves, USNM 221270; oblique view, showing concavity of valves, x1;

locality 6.

Pontisia cf. P. stehlii tumidosa Cooper and Grant ........... 00... ccc ccc cn teen ene e eee eeeeeneneees

24-28. Simulated partial ontogenetic series of articulated valves, USNM 221285, USNM 221286, USNM 221289, USNM 221292,
and USNM 221295; dorsal views, showing range of variation in outline and ornament, <1; locality 3.

29-33. Articulated valves, USNM 221295; 29. dorsal view, showing beak, open delthyrium, sharp costae and distinct fold
and sulcus; 30. ventral view, showing distinct flat-bottomed, inset ventral sulcus; 31. anterior view, showing high
ventral tongue and rounded triangular outline; 32. posterior view, showing shallow ventral and deep dorsal valves,
and smooth umbonal regions; 33. lateral view, showing short, flat ventral beak and truncated lateral profile; all
<2; locality 3.

34-36. Apical fragment of dorsal valve, USNM 221298; 34. anterior (interior) view, showing attitude of crura and their rela-
tionship to the cardinal process; 35. ventral view, showing attitude and angle of divergence of crura; 36. lateral view,
showing angular relationship of valve surface, plane of commissure and plane of crura; all <4; locality 3.

[sii SUE ES a hs pa clocHe ro POU OEE O COE OU APO AO CADDoe CONS COOURD DOU GDU nD OOOO OOS OODROOD EMO US ADO OST ODOR ON BOODS TONDO S2

Poorly preserved articulated valves, USNM 221407 and USNM 221408; dorsal views, showing outline and ornament indicative

of the genus, <1; 37. locality 8; 38. locality 1.

Pontisia:stehlii Cooper and! Grant. <<.) 0) y5, 50035, abs) steve eleye ates io olen rove aysieinioas) ls aie he ev syezaroneuere 6. ss)efoasesrelacenekeleyereieleneis yale hel eer eters

39-43. Five sets of articulated valves, USNM 221277, USNM 221283, USNM 221278, USNM 221280 and USNM 221279;
dorsal views of simulated partial ontogenetic series, showing range of variation in shape, form and ornament, x1;
39, 41, 43. locality 11; 40. locality 8; 42. locality 10.

44-47. Articulated valves, USNM 221279; 44. ventral view, showing shell outline and form of beak and sulcus; 45. lateral
view, showing truncated lateral profile; 46. anterior view, showing triangular outline, long ventral tongue, low fold and
deep sulcus; 47. posterior view, showing somewhat distorted outline and smooth umbonal regions; all 2; locality 11.

48. Apical fragment of articulated valves, USNM 221284; anterior (interior) view, showing disposition of dental plates and

crura and lack of apical median septum, x2; locality 10.

Rhynchonellacea, family uncertain < v..2505 ce )sake slob oars op wvnid ate olotay oo alaveee! ais: dealivelavs ‘ete elehecelsVavesehe of vereveianelelckereker oe eitrsen aoe eee tee

49-51. Three sets of articulated valves, USNM 221300, USNM 221302 and USNM 221301; dorsal views of simulated partial
ontogenetic series, showing development of shape, form, and ornament, 1; locality 10.

52-55. Articulated valves, USNM 221301; 52. lateral view, showing profile that is less globose than that of other Venezuelan
Permian rhynchonellaceans; 53. anterior view, showing low fold and broad shallow sulcus; 54. dorsal view, showing
open (?broken) delthyrium and characteristic rhynchonellacean form and ornament; 55. ventral view, showing triangular
outline and wide beak; all x2; locality 10.

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 7

mA tr Af
YAM, G i dj»

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 8

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 125

EXPLANATION OF PLATE 8

Figure Page
n=l, TSP Kaira TS aE)... o.oo os te oO RI CertO ORE CIO OID e Goorin a. cumicid concn a eee amen T COR inias Demonic ite nae ane 88
1-10. Ten sets of articulated valves, USNM 221308, USNM 221324, USNM 221335, USNM 221339, USNM 221352, USNM
221354, USNM 221358, USNM 221370, USNM 221386, and USNM 221399; dorsal views of simulated partial onto-
genetic series, showing range of variation in size and form, x1; locality 10.

11-15. Articulated valves, USNM 221401 (holotype); 11. posterodorsal view, dorsal valve down, for comparison with simulated
partial ontogenetic series shown above, x1; 12. posterodorsal view, dorsal valve down, showing small triangular
interarea, <2; 13. posterior view, showing regular outline and origin of costae at pedicle foramen, x2; 14. lateral view,
showing short ventral beak, equally convex valves, and serrate and anteriorly subtruncate commissure, <2; 15.
anteroventral view, commissure up, showing low median ridge in ventral valve median trough, x2; locality 10.

16. Apical fragment of articulated valves, USNM 221404; anterior view, dorsal side down, showing dorsal articulatory
apparatus, including apical median septum, 2; locality 10.
17. Apical fragment of articulated valves, USNM 221405; anterior view, dorsal side down, showing detail of articulatory
apparatus, x3; locality 10.
18. Portion of articulated valves, USNM 221406; posterodorsolateral view, showing portion of preserved spire and as-
cending and descending lamellae, <2; locality 10.
fey \re © lelothyridimarcres G- MANAalGOOPETRANGLGTANE 5.5.) 5 csave per si=y a stosaon cere cous sie (eatin nf eVox) 5) ones0ua cap eeNealo eel svat kev Ale vosegovevey ov vob orspayanstonater aachole 94

19-23. Articulated valves, USNM 221409; 19. dorsal view, showing size and outline, x1; 20. dorsal view, showing form and
poorly preserved spinose concentric ornament, x2; 21. ventral view, showing outline, x2; 22. anterior view, showing
truncated commissure and development of fold and sulcus, x2; 23. lateral view, showing comparatively globose dorsal
valve and truncate commissure, x2; locality 3.

24-25. Articulated valves of fragmental apparent juvenile specimen, USNM 221410; 24. dorsal view, showing characteristic
anterior spinose ornament; 25. ventral view, showing tear-drop form and spinose ornament; both x4; locality 3.

Es hem COMpOsitarch:, CompilulalCOOPeEn ANG, TANG sc 5eora oseyan-,a2opejnrale,snerencter eter tere tede tere feVe lets leh eso) vow ease 1 fo ee Taps es ave elo eae ISTO I, Saves orators 95

26-32. Seven sets of articulated valves, USNM 221420, USNM 221421, USNM 221423, USNM 221425, USNM 221431,
USNM 221433 and USNM 221435; dorsal views of simulated partial ontogenetic series, showing range of variation in
outline and fold and sulcus development, x 1; locality 8.

33-36. Articulated valves, USNM 221437; 33. dorsal view, showing smooth surface with faint concentric ornament; 34.
posterior view, showing regular profile and low, not incurved beak; 35. lateral view, showing lateral profile and sub-
truncate anterior commissure; 36. anterior view, showing development of fold and sulcus, and close spacing of last
commissural growth increments; all = 1; locality 11.

37. Apical fragment of articulated valves, USNM 221440; anterior view, showing pedicle foramen, dental plates, and
articulatory apparatus, x2; locality 4.
38. Dorsal valve, USNM 221441; ventral (interior) view, showing hinge plate, x2; locality 4.
Swett. (COST AATA TAT TENS TERETE Sis a hie bo CEES See ets ¢ cise GGritid a oc.s Aocta ba Sea aero eo sic Seis on Soe ae eaa ae cate eee ee 97

39-42. Articulated valves, USNM 221453 (holotype); 39. ventral view, showing size of a large individual, x1; 40. dorsal view,
showing transverse profile and distinct ornament of costae, x10; 41. posterior view, showing open delthyrium and
notothyrium and distinct interareas of unequal height, x10; 42. anterior view, showing characteristic surface orna-
ment, deep ventral and shallow dorsal valves and rectimarginate commissure, x10; locality 6.

43. Ventral valve, USNM 221467; dorsal (interior) view, showing straight hingeline and comparatively smooth interior
surface, x10; locality 6.
44. Partially broken articulated valves, USNM 221468; ventral view, showing position and form of crura, sockets and
cardinal process, x10; locality 6.
45-57. Neophricadothyris cf. N. crassibecca Cooper and Grant ......... 0.60 cece ccc nen cee nent een eee este eee e eens eeneennnes 98

45-49. Five sets of articulated valves, USNM 221469, USNM 221472, USNM 221479, USNM 221485, and USNM 221487;
dorsal Micwsrok simulated partial ontogenetic series, showing commonly encountered changes in outline during growth,
x1; locality 7.

50-52. Associated valves, USNM 221489; 50. lateral view of ventral valve, showing tightly incurved beak of apparent mature
to gerontic ontogenetic stage; 51. dorsal view of dorsal valve, showing subpentagonal shape, form and characteristic
oan 52. ventral view of ventral valve, showing more elongate outline and characteristic ornament, all 1.5;
ocality 8.

53. Articulated valves, USNM 221488; posterior view, showing open, rimmed delthyrium and healed commissural injury
of dorsal valve, x 1.5; locality 8.

54. Apical portion of ventral valve, USNM 221492; dorsal view, showing pointed teeth and dental ridges, secondarily
thickened umbonal area, inset muscle scars and flange bordering the delthyrium, <2; locality 8.

55. Apical portion of dorsal valve, USNM 221493; ventral view, showing blade-like bases of helicophores, x2; locality 8.

56. Articulated valves, USNM 221490; lateral view, showing profile of typical specimen, x2; locality 8.

57. Fragmental dorsal valve, USNM 221491; ventral (interior) view, showing proximally roofed hinge sockets, x2;
locality 8.

Sires S PVN Ne MATRA Gigs Se MARINA (CHILL Y,) 9 xvc gos teyors oor sic ane fons oo a5s Jo oe canoe acals ov akevas Mase leita rave oie ovavon olsce ove loaekeioier eps siege boosie cc rsumicree ye Sb meres 103

58-62. Five sets of articulated valves, USNM 221501, USNM 221505, USNM 221506, USNM 221508 and USNM 221510;
rors views of simulated partial ontogenetic series, showing range of variation in size, outline and ornament, x1;
locality 3.

63-67. Articulated valves, USNM 221510; 63. dorsal view, showing narrow beak and open delthyrium bordered by flange;
64. ventral view, showing shell form and outline; 65. posterior view, showing high, smooth interarea, flange-bordered
open delthyrium and small, low dorsal beak; 66. anterior view, showing characteristic ornament, subtruncate commis-
sure, final growth lamellae oriented normal to plane of commissure, and subequally biconvex profile; 67. lateral view,
showing comparative length of dorsal and ventral beaks, and subtruncate anterior commissure; all <3; locality 3.

68. Portion of articulated valves, USNM 221515; anterodorsal view, with most of dorsal valve removed, showing ventral
valve apical median septum, x2; locality 3.

69. Portonrot dorsal valve, USNM 221514; ventral (interior) view, showing hinge sockets and small cardinal process,
x2; locality 3.

70-71. Dorsal valve, USNM 221511; 70. dorsal (exterior) view, showing punctate shell and paucicostate ornament of somewhat
alate individual; 71. ventral (interior) view, showing hinge sockets and socket plates; both x3; locality 3.

126

Figure

BULLETIN 313

EXPLANATION OF PLATE 9

1-13... Neospirifer ‘venezuelemsis: (Gerth jaa :isscsczjs saves sarsvereresarstnteteynievorstore aie wor alae veins lavayernraterstere olskoms lal shefereie Stele eke ls hue steetele ese ene eee

1-7.

13.

Articulated valves, USNM 221495; 1. dorsal view, showing size of a large specimen, 1; 2. dorsal view, showing
curved ventral interarea with open delthyrium, incurved beak, prominent mesial fold and fasciculate costae, x0.5;
3. ventral view, showing persistent ventral sulcus and lateral fasciculate costae, x0.5; 4. anterior view, showing strong
mesial dorsal deflection of commissure, 0.5; 5. posterior view, showing very low dorsal interarea, 0.5; 6. lateral
view, showing typical profile with incurved ventral beak, posteriorly protruding dorsal umbo and truncate anterior
margin, x0.5; 7. posterodorsal view, showing conjoined interareas, <0.5; locality unknown (purchased from child in
type section of Palmarito Formation).

Artificial cast (USNM 221499) of articulated valves (NMB L4453, lectotype); dorsal view, showing size and form of a
type specimen, x1; type section of the Palmarito Formation. (Small black spots are air bubbles in plaster cast and
do not represent shell ornament.)

Artificial cast (USNM 221500) of articulated valves (NMB L4452; paralectotype); ventral view, showing broad sulcus
and pointed ear of a type specimen, x1; type section of the Palmarito Formation. (Small black spots are air bubbles
in plaster cast and do not represent shell ornament.)

Crushed articulated valves, USNM 221494; ventral view, showing conservative lamellose growth lines near valve
margin, <1; locality 7.

Apical portion of ventral valve, USNM 221497; anterior (interior) view, showing open delthyrium, strong triangular
teeth, deeply inset, mesially separated muscle scars, and secondarily thickened shell apex, 0.5; locality 7.

Portion of dorsal valve, USNM 221498; anteroventral view, showing small striate cardinal process, large proximally
filled sockets (distally broken), diagonally striate apparent adductor muscle scars on apical flanks of mesial trough,
and internal reflection of external fasciculate costae, x0.5; locality 7.

Articulated valves, USNM 221496; ventral view of an apparent juvenile ontogenetic stage, x1; locality 8.

Aneuthelasma'globosum Me SPs 5.8.5 cue cexe ascters sesberoge ie eh etecyeetedeheeie eyes ee ol lstelensersaekoleteicveratelatetteTsieiraie a) peter heteiaie es eee eenene 104

14-20.

26-27.

Seven sets of articulated valves, USNM 221516, USNM 221522, USNM 221526, USNM 221529, USNM 221530, USNM
221523, and USNM 221520 (holotype); dorsal views of simulated partial ontogenetic series, showing range of variation
in size and outline, <1; locality 6.

Articulated valves, USNM 221520 (holotype); 21. dorsal view, showing broad ventral beak and subpentagonal shell
outline; 22. ventral view, showing shell outline; 23. lateral view, showing straight commissure and shell profile; 24.
anterior view, showing equally biconvex profile and non-folded commissure; 25. posterior view, showing somewhat
labiate pedicle foramen and broad flat ventral beak; all x3; locality 6.

Portion of articulated valves, USNM 221533; 26. ventral view, showing lack of inner hinge plates and remnants
of short loop arising just below hinge sockets; 27. posteroventrolateral view, showing position of origin of loop in
dorsal valve apex; both x8; locality 6.

Spiriferellina'cf.jS hill (Girty) Pte... eect <feree ite teteeeietor <r ehclorele ola tec ielniaraaieraisteleieisietere attic icielaciet te leita chat eee eet ee

28.

29!

Fragmental ventral valve, USNM 221512; ventral view, showing ornament of overlapping lamellae, seen in some larger
individuals, x4; locality 3.
Portion of dorsal valve, USNM 221513; ventral (interior) view, showing hinge socket and socket plate, <3; locality 3.

PLATE 9

VOLUME 80

BULLETINS OF AMERICAN PALEONTOLOGY

PLATE 10

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80

Figure
1-4.

18-29. Texarina? cf. T. wordensis (R. E. King)

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 127
EXPLANATION OF PLATE 10
Page
CHINA Gas, coornecroscacodotosebpaccS noo ee Gmoodo OD ODOSOUSE COED ROODO OOO OOH beHOOOEGODAeOOUGOGUOeSECOOOboDDEAue 106

Articulated valves, USNM 221539; 1. dorsal view, showing size of a large specimen, x1; 2. dorsal view, showing broad ventral
beak and narrow outline, <3; 3. lateral view, showing short beak and globose profile, x3; 4. anterior view, showing globose
profile and intraplicate commissure, <3; locality 13.

STENTS MIMICS Th, EE BOGE, coceanseoconbenopuMbooooec noccoh oo SoD bacdodondoaDcoCUDDDDODAUODDUA OOS OEONODGOOLOOC

5-10. Portion of articulated valves, USNM 221552 (holotype); 5. dorsal view, showing size and form of a large specimen,
x1; 6. dorsal view, showing subtrigonal outline, rounded commissure and telate foramen, <3; 7. ventral view, showing
subtrigonal outline, <3; 8. lateral view, showing unequally biconvex lateral profile and short, incurved beak, x3; 9. posterior
view, showing telate foramen located in plane of commissure, 3; 10. anterior view, showing rectimarginate commissure,
<3; locality 6.

11. Portion of dorsal valve, USNM 221553; ventral (interior) view, showing complete, apically perforate hinge plate and
origins of loop, <6; locality 6.

12-13. Portion of dorsal valve, USNM 221551; 12. ventral view, showing hinge sockets and distally broken long loop; 13.
ventrolateral view, showing long loop of apparent early ontogenetic stage, with posteroventral flanges, anterior
spinose projections and anteromedian dorsal transverse band (see shadow); both x8; locality 6.

14-16. Fragment of articulated valves, USNM 221550; 14. posteroventrolateral view, showing virtually complete long loop of
apparent mature ontogenetic stage; 15. ventral view, showing relationship between hinge plate and loop; 16. oblique
anterior view, showing relationship between loop and ventral valve articulatory structures, including dental plates;
all x8; locality 6.

17. Fragment of articulated valves, USNM 221554; lateral view, showing apparent late ontogenetic stage, and long loop
without transverse band, x8; locality 6.

18-23. Articulated valves, USNM 221555; 18. dorsal view, showing size and outline of apparent juvenile ontogenetic stage,
x1; 19. dorsal view, showing smoothly rounded fold of dorsal valve, x2; 20. ventral view, showing pronounced
ventral sulcus, x2; 21. anterior view, showing trigonal profile and pronounced ventral sulcus, x2; 22. posterior
view, showing short (?broken) beak and striking trigonal outline, x2; 23. lateral view, showing curved commissure
and characteristic unequally biconvex profile, 2; locality 11.

24-29. Articulated valves, USNM 221556; 24. dorsal view, showing size and outline of apparent mature ontogenetic stage, x 1;
25. dorsal view, showing strikingly elongate, narrow outline and anterior asymmetric folding of commissure, 1.5;
26. ventral view, showing asymmetrically folded commissure and elongate outline, x 1.5; 27. anterior view, showing
asymmetric folding of commissure, 1.5; 28. posterior view, showing low, short (?broken) beak and unequally
biconvex profile, «1.5; 29. lateral view, showing elongate, unequally biconvex profile, «1.5; locality 11.

128 BULLETIN 313

INDEX

Note: Page numbers are in light face, plate numbers are in bold face type; numbers in italics indicate principal discussions.

Gages, Lophophyllidivim ........0-c1ccecceveevceneceneceecnesencce een eeeeenseeeneneene 20
DANG GAIOIA Sl Decoconcran: caeeeecbosaeneuco-oncerncesce-perescecuannoncousnescancomses Zev743
INe oleate \MHITENINS: aooscoceesennocoonespchtecoLceeesoccentioc. Hunacsaqoccoconc cord 39
PAGHTINODECLEL (acacase seaae scence seine sesees daeestnahier =aaert ia an-mesemsie meer asenn seme 25
Sarasa oe as etre ae eene abate cas enna ae lnes= ms tntnsr-naxveacescsaee=ywescrasannnsnnnn cannes 25
MAGAN{NOPE UX OOS acces sane nne enema aennee Direaxs 2), 0; 5173s St AO:
Acolosia Cooper and! Grant. «<<. .-5.n.cscceessavecnsaserasnanvevarsesseseccereneseserns 85
ACOSGriINdl COOPeM ana Ghana nescecawens- cess enavesetscmscnca-isnes=senesen 14,40,41
dorsisulcata Cooper and Grant ............--00-+0seceneeeccncecnesrcossoneeresses 40
TNC TITS ena cace go Re ROC eH SCC OLE EEE DCC SECOOE CEE CRED LEBO CALICO POSE CREDO CERES 33,35
Sp ppanngeoneuendehi obo -BECee FEEere aparece sneese rp -oberccoransr soca Weise 26,40,41, 118
PAGH ALLL ISP eee senog eee ane sce iantngenin oceape ane = a= ae rnmemn sme ielinax snares 21
MUR ERENSEXENLOSTE LE Sime seceeaccete cee nces ar eereece cael ttenameneeecteenceanecsewecas 55,56
MelarOPlossan(Gh-) wi ap lis tiommerte tear tee enecat ass ccnessaseeeanetes: Teese 29
GEQUISUIGAIUS, PUPNEMILES cerenuiecesels--aerver<0-aaemannatematcberescsenrass ess === 28
GffinisS, COMPOSUA <..-.cccs=encnnsseeeeensi===snca=seowondesetnusannlersacerae--1/eaer=s- 96
INIT. cosrosceraescecoo eon 22ceece~ so roa coc caBOOOoTNEnEnOLSosoocosnpoCcOnCHOoToBES 47,57,62
/ NEGA OO E Neresesecnecsssocenscnr apace sc0cc ac aasceeseenoepeneo chee casaocoscenpocBneoae Carey
Aguardiente Formation iL
JNU TECHIES) Saccednedecantosoncoaccubet sence Sdontessena6sc sag JU
HANG, QUIZ OV ATATIEL soncosseoatnoseqen nnbcoanocecoscacodsnncosAOSIOMHaIS 105,106
PAULOF IV TIGIUSMWICILG Geetin caer ae aee centeecee se nemcnedece seta ewot nee 5 8S
AU el LEAS (Sie Nao qoer neeenrepn ch opeceoehy donors syuecceor=3209 . 102
JTS scceenseesaueso-uossecebce can-aoancosonceccacteeeoacecnn HS
Alveolites 11
AIMDIBUUSS PI f Claaaseseaneece seat renee sas ... 94
americana, Collemataria . 84
American Museum of Natural History (New York City, NY. U.S.A.)...... 6
amphigyus, Neospirifer On
CHEAT CAE TEVICIGORE concecencoreerecce Ce cec0cee son sooconoeS TnCoSSOsEcoOARE cceoneteo 91
amygdalinum, Aneuthelasma .. 104,105
DY NTTGRAS SOs TG a ecapscondcaqqanconeo 20a ce JAB OaCDOQESR DCO SOTaSCCoAT ER TageSEOndSOSS 28
Anaptychius n. gen. . . 5,14,25,33,35, 106,107, 10:
MINUIUS N. SP... + ‘5 §,24,25,107,108, 127
/ MWR OS ANE Tel! Lele bi. consonesscesatoocoonincovaossconoosgbiocoodsessnoeeccasta 8,10
andersoni, Rugatia ........... 19)
Anemonaria Cooper and Grant 5,67,68,69
inflata Cooper and Grant.. can (OM
sublaevis (King)............+. . 27,67,68, 69,70, 122
Anemonaria? cf. A. sublaevis (King) ..- 20,29,68,69, 122
Aneuthelasma Cooper and Grant ...... . 14,33,35,104, 105
amygdalinum Cooper and Grant ... 104,105
PIOVOSUIMENENS Dacecasaeeeteees tere §,24,25, 104,105,126

angulatus, Dyoros (Dyoros) 51
angustisulcatus, Chonetinetes 55
PAITESOPY 2 Cy teenctecaveusanseeoeteaencnss = SLO
2inornata Girty .............+-+- A son eit
PPL TUAGIA US NUT ETR OD enesnteeso de enon secon sae coeeeaosnobeeascoceecec none seed 28
ANOTIAIUS; MEN OSLO QOS Ie cave svees sencinactiens suasenencesunnent seUee chee wccrerennencuents 56
Anomphalus

ARSE HIQMMe MMe rand Men eGares-nessen-ceaece--2- aces -ehaachene: seems eaeeneas eas 57
FNC eC ears 5: dace Rc BEES EE Ea COnCt Gio: DUOC ACE ERDE RSE DCEE net ee cea sus scbocc que ece 57
AV gUOTO/IIC, MUOLACOVICH «. 5.sauewas estes cues sane: oases eee sseAseeee cae 17,72,77,80
AnIrOnaonigneooperiand) Grantiees-s.cccscccessontcuce ve nestacdutersoesacecresteccis 85
Apachella

BUA TANCISCONAI(C MTOMNIC) fexinessrotenc ase. ct ere: seem cere secon a Ces 21,29

See Faroe ene dealer crs wsinn tor «dencanteds ines taceyssuaipdscasnstee reas emeereeect 23,29,30

SPN leecsessascccsesecees Iwan dddanducnraupancavaWs teascnvee cen teessee tere peneets 21,28
FADEFISDIFIEDIW ACELDOUSE : 505225 .aanescevcnwacisdees «os cososssdduecsaten de terete 100
PAD HAUrOsImaCOOper aNd iGrant, cacecsaecssercene ons occ cvsenes dena cerscvesactinceesenee 85
PEDHELER IG OIIPOGUG tevwnaicchadioretcescdrvddtccsuassscanaacntancatatneeteet terre 96
DUM ESLEIU ASIN EOSDIFUEl. aaccducacecesccugssancsatcaqncxtossecsante ties e mae 101
PeOPAMCMIAMLSeCOSVNCINAl DELL ci.t cp-cecssreostusscaciscactncceserccstnc cement oT Ee 8
ADMIT PAO INOS esc ce senses sndcvsieslsichecendvenstivrcctddevesvanieesucitonaeneeeee 96
ELLIE CS ATTEOT ETRE ROE Ao: PEPEP PEPPER EEL OPTTT PPPOE AY PUREE Rete Groe te: 101

PAY RONEN A ieseercce cnc. scence<nc eens aceoe= ass enat ene naman neta Meneses ass tae eee 10
ArionthiasGooperand Grant .....<cconeseen<-2seeser see cenen ee entees es eee 102
ATIZOMNAS 8255 cess sein cosecadesccsvereeccdaseazpescces cobteens donsetaae ieee et teneinaaeesaa Ti

Grandi@anvond Toceiicessecsoerctecersaccess sesadiesscotht hee nedee eee eee 79
Arnold HG. .ccc cscs. sss cvceoncectecnescan’sasa05de-detauns caver RCE ee ene eeeea 74
Aumold| (1966) )rsessesen-ssveseeee>eesseeeee 8,10,12,13,16,19,21,31,33,34,36,74, 101
Artinskian/Strata .....2::<.ccrev--.0seeeensssecsrecdeos-nasess0eee tate ee 16
GSiA1iCQ, SQUAMULATIA, 5. 0...050500ae-nrenssaenencsesieosmeceone serene eeeee eer 98
Alstartellaisps) s.cscoscccseseeene- 2 ncapes tive sesso eee Pe 2
Atelestegastus Cooper and Grant ............22-:00ccneeeeeee csosasaes SOR

Athyris roysii Davidson .............. . oF
attenuata, Meekella ............0.2055

Alttenuatellay Stenliiyccesss2-seeseesensses==ee .
attenuatus, Dyoros (DyoroS) ......-....0.0.+ . Sf
AUUIOSIEZES. <2 --.4.-20ccccorpoes o ae

subcostatus King ....... .. 74,76
auriculata, Paucispiniferda ........... -- 69,70
auriculatus, Dyoros)(Letragonetes)) -.c.-2<02-seaee- nen --sceeesestaeeeeeeee ee 51
Cid adee JOXFUMU reeeocneretocescas z 5§,22,27,30,42,43,44,45, 118

Australia ......... . 37,47,57,62,100, 102,104
Aviculopecten sp. repeat: 29
AWVONIG cae fc ssc occas seuseeahe ds taene secede cadences see woneee ne ee to Ro TERA ae 17
Baigendzhinian stage .. eSevossvanen oe

Bairdia (sensu lato) spp. .
bakeri bakeri, Neospirifer
bakeri columbiarus, Neospirifer
Banks, P. O. ...
basiculcata (cf.), Discotomaria

assis Peniculauyis: yesecnceresness eee eee . &
Bathymyonia Muir-Wood and Cooper . 17,59
?Bathymyonia cf. nevadensis (Meek) . 74
batilliformis, Collemataria ..........00.00600- . &
Beattie Limestone, Florena Shale Member . 45
Belize [see British Honduras] ;
Bell (1950) .... 38
bella, Echinauris ........ 25,30,62-64, 65,66,68, 121,122
Bell Canyon Formation 14,48 ,53,69,83, 104,105
Hegler Member ........ . 54,35
Lamar Member ... 54
Rader Member ............... 54
Bellerophon (?Pharkidonotus) sp. 23
?Bellerophon sp. indet. ...... .
BellizziagiAss. cic.s.: oes. sdsive des uch acs. ate. cous lessees aesseen cece eee a

padcbadotoso sco 91
10,13,45,94,102

bipartita, Hustedia
Bolivia ..

Lake Titicaca a. «ca2iicveviisdeacousevanwsivs apleltcnksl tags fetwansese ct ene eeeee eee 6,86
Bone: Spring Pormationy cs .-<ccc-<-<nsnceneesteee<ceseee sees eee 41,67-69,77,81,99
Bonham-Carten (1967) <ccesccceosgssscuiecevvnentece opsveweneeeeanepeaateeeeeeee teem 1S
Bothrionia Cooper andiGrant scce-.+--ccunec ees -aqs: eseere nee terest eeesee ee 62
Boucoty Aw Vi icciehsc.ccmn vamaneedcinecs svete cas tedeces dee ete eee Ree Rene 33
Boucot, Johnson} and) Staton) (1964)) ...........--seccecnsusesouwecsemeereseeeeeee 88,92
Doulei; ECHINGUTIS,...cccewecassth-cakea ve wv aca te cavers Sone ap es ese Eee 63,65,66
Bowen, Rhoads, andiMcAlesteri(1974) <cccse-ceteen/ee seer eemesneeeceeneat 23,32
Boydand! Newell) (1972) = sicsctusns cave cseaeso0sansusueeeees Waeeeaeeeamneseets 18,19,21
BYaZil wee... ccccascececsovsanuae scacsaveeesoscs sacs scess se edeus Geeareaceeen aa ee 10
Bretsky and! Bretsky? (1975). cccecer. «+ 0k cee ere vv'ane need sapesseee steer 23,32
Brigham Young University (Provo, UT, U.S.A.) ............+ssccssssneseseenenes 6
Brill (1940)

brilli; Pseudodi@lasma .... ccs: ccvess 2scece00 ces degnses iscssmng ee eeeece 105
British' Honduras: «.cc.c.sccdevescececeascevs ouesesecsssvcee ste = sreet eee eeeeeeeee 9,13
Broili (1916)

Brown (1849)
Brown (1953)
buccHlental ‘GOMpOsilal wratacerecnsuncpeadecdtestaens a neret sor Candee ee teeta 96
buChi; Der byias ceciceecocascticisscaccvceveaeeasustsovdseauenrssesi sscnscs conaxaeeenamte 45
Buckmiani((1906)).-...cseexesaost «ce ecnsaeestccecncdedeactsvassevesteee nt ee Coe nem 93

PALEONTOLOGY OF THE PALMARITO FORMATION:

shllendlara is (WUSSS)) iessacencdocnesgesebesncasancepsoosnassoncso soe odsa desu secuscnapedasnba 8
PALIN COD NNIGACOLLY MUS twanise seneohscanr atest hitet tetas itanentareenstastateesic 99
STIG EIN (LOTS) eco scteccacaties cs cosieccccssccsavacceccsvsstessscvectedeeseccncrpcarersnceceesse 9
Ree ey SPUN UE eesti ceecrecccuicecsccecstieesccccricscctatenecaeusaseeziceeaeracay 6,20
RSME Vir tcneccor atc sacchocenesecnasce cctecsercarsses(cetevsdeessetdeesteecstigsaventsersreesse 6
BHIIPULIIGQIVICEK ELIA’ 2. ccnccansesscsedecshtedasetvssccsvse scans suacucesescessacesersness 48
California Academy of Sciences (San Francisco, CA, U.S.A.) ............608 6
aluispirina Cooper and Muir-WoOOd)...<.....2....2...ccseecvosecen-suvevssnseraess 102
Bree lsInaa ©GOOper and) Glaniiners- +s ce--scr sce ecccscnecceeeredaaecuarsecvecuvers 104
i" HTID@GTE _2erecdoqnbshaebandbonentoboone <asseeesodeebodaasestnanecocodcedecostocnsecbsaderd 57
(ELAR LL Es IMCOQTTITE DS acesebeosandesarie saodesonrapcceosencmconencaseebeocoagnaccse 101
BEL AI LSAVETEZUCIEIISIS® WS DIN Cle -nactase- ses seacrcechecesaedasencn-necaresenaescsiers 100
—rThopgrell] (0251S) es teeteaecepnaeanssce ac SeseSenelace a MesBEsomnanae iogteseabaasuceoacadoss
Campbell (1965)......
BPD TIDESI US MS PILI ChEUIN Ai ccienscdstaatosesrasietscccisrascree tecesdesesecetasaemiienesaes 102
BEMIS SHES CHIZ OULU Srnsctncmor at cvagccectarecendeene corte se eriencdeccceatcees see cele 16,20,27
MLGI IIE LAP ar rece core ce si cre tericee ce csene sto sje 25s dake Sedans daisiaes seaaeeecnees Severe 17
| DAO) ROTTTEUIO Nga wasecaaseceanedassedescosk ao boss adc oesoeboe nasa Beaneakendbe ecboceees
| ETMT RG TELAT agesteneceacosceoneehdupacneoscoosneceeeapesco rncn
MEER 8) Mee erste tec cocer res ae acon tet onerccas ec aseanzesnovivusecepeatemevepnent ict
__) MIFIRQAVT SIBEL eassetedicndnads Skuasane dad sedao sanhBDeBeBe seme semadacosasco ssec oseboasen
Cartorhium Cooper and Grant
Case-Western Reserve University (Cleveland, OH, U.S.A.) ...........00..2. 6
MELON G NE ODNTICAC OLIV MSiieacnertieccececmcnecse one -lrin- ose cor cme sense stmcien= 99
MPCEE COMERLAST CCI Cmetettncearcciss Soc oce(ean-fesee (ac venette cocoate deiersens eleadiics eae dear desa sss 91
Cathedral Mountain Formation ..................22:-see0ee0 14,16,31,43,44,55,67,
68,70,71,73,77,79,86,87,90,99, 108,109
BR MEN UL? ESP) shane cocci See secs welecns as sb ce vaivers face Se uieiee sashes cteilesusadtsewasecned 21
DINE LILES D SERICR nse ecenen ees esosane cert oe ageeeecies Sielsescseeaansnsslineoas se nterees 25
BRECIO IEC O5G) Mecrtecre test ne crcnec con acucsvoseree cs sauces doses Senne neces Secaewe se cae 10
RPINGCUMEIUSTCCIG .accccc caste os tess secscenscviciesett ose cease iiencoeseszavecstesaaes 91
LUPUTAPARTNOY Ss a oatemenetleneat estes ia meee eet am an ee nanan heen ema 21
Pair benainen Canker ners. couccucasesscedtbassennme aaticasectensinesse canvas clase 6,16,28,30
MUR PAONIE S201) te crcats Be ce cirna ielviice ve ridsmz siovsvatiecntls oae ce duelusiivencinsete lass seacie 62,63
BREESE epee eee ree eeae ono tira gar Neder nests cilawunak Sane teevesl-s pes ie deren ses 98
BARRED LIMES COLIR Stns aa cie ae fe ne dso en se eee Waxea wee Conn one encanta ne
MENUS) rn arena Se ccen caavasausxcaseNeatescecccccencceweavaynaetancverssacnaavecess 18
BPE LOAN PANGAN AZ EN AIO). ccc apsn strane sceceseneevcclusaicaticesersneecuaneweaceta wai 14
Cherry Canyon Formation ......... .. 14,40,46,48,108
MilemNiadresdesDiOSvATCHIPElagO! cret-cesceosce -ucscsescueaanseasssuscececcensss 10
MMI MPR nee ete Ee cn ado caa elon sv cies cecivestis cocysccerk devedeucensseacqress 62,63

Chochal Limestone
Chonetes consanguineus Gan F

Chonetina Krotovy ...............+
Chonetinella Ramsbottom .... SOxkeAeinoec ead
Chonetinetes Cooper and Grant...... ae 33539593), 54,55
angustisulcatus Cooper and Grant es)
reversus Cooper and Grant......... 33555)
varians Cooper and Grant ...... pebeeenoe ea sob)
ef. C. varians Cooper and Grant 22,27, 30,51,54,55, 119
SURLES RM Eocene cee ene SP oc os ces de svatea sass see sti sevasaesacasdede ces claasoecsses 101,102
@hrist((1927) ....... 10,11,26,102
meibecuia sp. indet. ..............+- eee PA
Cibolo Formation : Nex 90
cincinnata, Derbyia 43
circularis, Echinauris 63,65,66
ciriacksi, Cleiothyridina 94
citeria, Hustedia Has 55 Hil
Gities Service Company (Denver, CO, U.S.A.) ...............20eenseeeseeseeceeees 6
Cleiothyridina Buckman 14,22,33,35,93,94
BREEN SIAC OOPEE ANGKGTANE ca coceirsccnes wecltene cen cuuier secede ajeaces nias «mse cane 94
BPELCa SMO DTOMIC seceaeias evans aelencarilereeerios canis suse ceca xcte eecctestoch yo Sessa eae 94
BIISARC OOPEANGUGANG --o.esce-tseecacas nese con cussssee won se cas pecteceseessioese cs 94
Batre OOD ERLANG Granitarscr.serce ster neces oecec crocs cccenans ce jeeneaane seseesere 94
mienG@t7a0) Coopermand) Grant: seccesecsrsessereereesssneeces Shee 21,94, 125
RR Miar ise GOODE. ANG Gian tenets crcvsaneevenscothossn jor sv¥s see reeons es oneree ans 94
BEERS OOPEN ANG Grantirs ocescees secs ress cos sacee snc cos sues deveesasssnecesceaescense 94
Bernrmrareinata Cooper and) Grant, <:sscce. sc or-<- wees cacss soestzarcachiessseeeoss 94
BeHOISHe inal ((L974) eee eee cee we tar erc eres each saree troche sce tenensndeseenese 9
Cleveland Museum of Natural History (Cleveland, OH, U.S.A.) ...........- 6

HOOVER 129
Collemataria Cooper and Grant.. ». 14,25,33,35,82,83,84
americana (Girty) .......2...c.s00e0: edd w. 84
batilliformis Cooper and Grant . re Ot!
elongata Cooper and Grant..... 82,84
gregaria Cooper and Grant..... 8&4
irregularis Cooper and Grant .. 84
(ACT SICAIRU SGN) sébecsooceccoaaccoanokadeee 84
platys Cooper and Grant .................. .. 84
spatulatar@oopenanglGrants sercstrcssee-cseetes seen ant sonce tas contests 83,84
VEMEZUELESIS Ne SP i icrae tenes: seeradeondnenusmen ewenauees 7.210. 5,24,83,84, 124
Golomblalrec ces isectreosaeescensnmetedeatseacedeecd acca smolaneses sacitns ach teemceaeae 912,13
iemma der Penta icacioantscacectiscuarss san susee suse neck eansene ote saese aan neeeees 9,16
ICOlOSPONGIGISP= -oscxsnsncc dee sasooes ca hes aeenes Poors eu utes act oe coc oteee ete eee DDD)
mC OIDILESTAISPS AGEL.) . lecaneresiscsdancwattctteet secs nteneer loonacesee anc acco eteneer 29
COMPLEX DICH OSLASIA™ ccc an ences facesatonee -asere see eten Sete neo ra Seer See 22
COMMPUCALA,s DErDYIAl seedecavesnensecnacsees cone ettcetaentescaecnnanieracenseneree 43,44
(COMmplicatan (Ch:) Denby Gimmie taanataenatensee eae 1 . 22,27,43,44,45,118
Composita Brown. .............00..0000008 14,17,19,22,27,29,31,33,35,93,94,95,96
affinis Girty 96
aphelesn@ooper andy Gran Graurracasee:sosceaces tear ease seca eeeece ei eee 96
‘apsidata |\Gooper and Gran teas: sec-ssencsdaccueceentteauesetceneas cere tates 96
bueculentaiCooperand) Grant-ssseerce-terestnteeaccnearoecnaccceranseeetenetees 96
Costata; CoopeanGuGranite owicceciiecses sewes scoun vs carcteesesteceravenaeicetecan 96
cracens) Cooper andiGranteee-eecascecesaaeas she enaseasrcecacseaieeneseaenreerene 96
CLASSAMCOODEG AltOGbant, sacasnes semester ence cece sae siene ss ce ear on eoeee nema 96
EMARSIN ALAN GIATLY ar emancente ces ence ances caeendcn omar enter once ene ecanee es eenerecere 96
CROLNS COOPE ANG GEANG, ces. scons fe eee eetar e te ee ace een eear ences 96
ST AMAIS COOPER arenes den oae <scrocsncdsinaeee rc oaceenn ced acseevei ane st ase enee scence 96
hapsidagstebliands Grantecsecrcessseseaaseesretet eer aaisenaestenes see eeeeerEneteee 96
EPiDriGatduc OOpel ands GLAU be seennseteaenenente ate sagt eae each secs ee aneer ee 96
mexiGana all) oracesensesce ces coe onsnesi orci tones ony ac sce eacoee sae wet eee ee ones 96
Wmainis Cala’ CRLOMG nes news seine ecsnesccanasssi-cesdtes oasiiceabesees Seance snacseseee 96
nucellasGoopergand) Grantines.csceastsecsest testes sercececeecenecsccereeeestrans 96
parasulcatas Cooper andy Grantaresnn merce enetecerenceeertteeesecee tees 96
pilula Cooper and Grant 95,96
ef. C. pilula Cooper and Grant ...... Since 20=22,26,27,29,30,95,96, 125
PURO OGM COG EUG GTA ~cesaasaaascdoosocsecnacconseseadeocodescconca-coscase 96
[DAO AAD (COKE ETP EWG CHENG. a. inacenacanaeoosnocogoponoseccopctoneudsbass000ds0006 96
Quillen hia COoaer Biel (GENE -poccconcendooedecod soonesecosconeaucosancapocaeees 96
MMOD COOWERAING! GHAI stsceohescoccsansceascnasessupser edesnseebeoneenes co 96
SUD tilial CEL All) ptescsssssecs ce cavescabienavseea nen eee hee sae aero eee rer caaee eee ee 96
peruviana iG RVOMIGC?. cn. .c- nce ecae-Wean-aroeecntncoep ener iaene su teseaaceacheeee 96
COMPTESC A PAUSTECICN sere cuacs smcteomianiiee Waser cae ater estan eaten eee 91
GOMUGUIAEGTAN tere sane aw. sulssxeauies Seshic dane eeosns seresiea dec busee soa coenseasisecees 70
(COME INCA OCG DTTS coctocece:coeccecob: pabbec cobb acon OpeenorgUrecbOCnecnEntOLen 99
CONCAVUS 7s DY OFOSy (EUSSOSIQ) Necseted en aceesensesan essen scaetine sneer eee aes reeset 51
Condrathy ris Minato: ..cc0.ccsnecn ace satniontee si cook en saeete nate ace se docsasenaaees 98
GOMMOPSU, TAUSTCQLG | (oon ncolsenes eee csee selesencnien esto: avs we suanane en sasewercbareesanese epee 91
consanguineus,
CHRONO ES «deers ces cea nndan estrone “a eesaiaanetene se sess ctaeeeuriasnincsecessepeorneeeeane 49
DYOFOS:(UIDY OOS): Fecescece des eee receeas bs oes Sese > Suse a eee debe heOR Co ee EEE ee Sl
COMSULA SELUSLC RIO Auctiea- fants esr aeaee) teeta tee Peete shee nc aes ce eceaeanaeerite 90-93
CONVEX: RUG ALIA trevnccnesacescmsntascaens tae eoescine suche ee ve steasaenna dace ceuaieeear 78,79
ANIME TS 1 OS ETOS: (WBXYOTTOD) eenosccnonrccanc:nanooue ese ssoneacodene SacpEo-ceonbaceseaee SI
Cooper iG Argy oo. cscs oncadere neces sc cee seeeies (eae sectaencs au otea Sas sa ate nies 6,37,45
Coopers (9S 6) meen ccc copper hese an ouer seats sas dee cctnaceeaeua sevaneecns 104-106
COOPEH (LOS) asec sseescine cqecis sents dete <tc Susie wenmeaemeeetancues canesee teaver Su asetecne 96
COOpenQlO7S) ceccee cess sen dctoemeuteer teal t.aneoeeeeeneecnnes cave dspace cn apenas 41
Cooper andiGrant:(1969)). 5 cccsecccsescnsanceesmees 40,49,53,55,57,62,67,69,72,75,
83-85,87, 100,102,104, 108,109
CooperandyGrants (1970) eecnenecccoctecsnenenese eeeceareeteceree saaeecee eeceeeoereee 108
Cooper and Grant (1972) .... 9,13,34,38,39

Cooper and Grant (1974) .
Cooper and Grant (1975) ..

9,13,34,38-41,43-49,82-84
9,13,34,38,39,49,51,54—-58,62-73,76-81

Cooper and Grant ( 1976a) prcectc 9,13,34,38,39,84-87 94-96, 98-101
Cooper and Grant (1976b) . 9, 13,34, 38,39, 88, 90-93, 102-106, 108,109
Gooperiand!Granti(uoi7)i.-c-.cese-- seer ernes besetees -- 9,13534538,39
(Choyoy PETG) ITN ool (CICS) fon ncconeseadsauasssasecsone oechusseorenncannondes 102
Cooper ietial. (1953) sc neseseceesees . 9,36,67-69,73,77,78
Cooperina Termier, Termier, and Exim . 14,33,35,57,58,59,61,99

inexpectata Termier, Termier, and Pajaud ...... 24,25,57-61, 121

130 BULLETIN 313

Cooperina parva Cooper and Grant .............2-2ee0eeeneceeeeeeeees 57-59,61,121
polytreta Grant me es
spondyliformis (White and St. John).............ccceeeeeeeeeeee =. 38
subcuneata Cooper and Grant .............- 57,58
triangulata Cooper and Grant .............. 57,58

Copacabana Formation .......... 86,91

Copacabana Group .............. 10,13

cordata, Neophricadothyris 99

COVTUSALAN Che) ste OFT RENICg i eee erccscecnatcerdiccneseasersceecnascnrne =, 23

costata,

(COTTRGRID « apecna-cSecb PBS COCaCR EAE COTO COORG RCOg: COCERC COC EedOanccoasenmannetennbas 96
IRENICUIGUTES, ccccencscescassestee daa rescaeatpscersetesceasecsceces «vasenscasesdrenavecs 76
IROMUSIQ--e7-42-0- 86

COSIGIUSTUROGUCTUS ce sisson ccs sodseca sce cccees saawecencatesoucsicccnteccaac seo eenetannee 78

costellata, Paucispinifera ..... 67,68,70

‘GCosicrura ma cenecsssescsen-eeees 5,14,25,33,35,96,97
IDUIUL LN SP stone eccunccet ad enecsase seen ceresr Site ons 5,24,25,37,96,97,98, 125

Costiferina Muir-Wood and Cooper eh FUT

Costispinifera Muir-Wood and Cooper.........-....cssececesecsecenseecneceeneeens 62

CVE 9 (CO TI DONIC pres 6c CE COA ORCC ERODE ACOH E COE EEC DECCER NEO NACE GE ODOR OCEDOCCOEE 96

GranianRetZqusi.cercs.ccenec arc ctoc etc nooner c sae see scentec dee aeeiseaduaoess enees 39

Graniellanmeduanensis Oehlert mms scceccosatecetececsnce aeeenen eeaen eer eeee 39

crassa,

(COTE TOS THA cedccbadbeerpppeso cetera -oErDatecceaLoencp ce Conus mace dachee sosesCureesadnend 96
IDYAAISTT he eee seicee RECGSCB-e CDSE PE COE EDU SCE ECO PaSCEE SECO OSCE COBO CE RDO DR OOEE CECE CGE 45
IEGHINGUP IS) (a ieecs cicsceees ke dyseosecs es ie caceck oa da cess sdsncecacvesewtascasaes 63,65,66

CrUSSiDECCAmINCOPAICAAOIRYNisseseatea a eeeee poate eee ear nee 98,99

crasstbecca (cf.), Neophricadothyris ............ 3) sieeco 20,26,27, 98-100, 125

CRENUlata, Der DViG! (occ scccscoxsececvanedss setts ooccvecasesecaeceadaevewscnecceee race iet 44

ROD AX MEALS LEC ie eee once res ae Sete te iene see ve eee ran teeter eee ee eee ee 91

CVISEQUADBS DIM FEL EUG araccests cotnes sens santitpentiifeeua cane anes deeenet sie eee 104

CPISLQIUS> HENEDEALUILCS. 2 -ccvasccscacns=c 207+ s-nda cee eracsenccenceenvett eseatateeenees 102

ONUTI CENA AT Cenc enrens sete aencce eons esee eect aera nee meee e a ence a ceenits Soe Coee 25

Cryplacanihian White and ot. SOHN) 2. scsecec-sscennaenaatcos yr Soaneaseeuusecsvenss 107

Grypromellaptial lMmemtcseerctecs scores tacceet se cack othe ceene wane ietoct Sense cE eeR a 108

QUIETIMNE HELUSTC ONE = vax cece soca oon seegeus Aeee cadec dh sec Bane ue ecner ona aeee eee RE 91

CUNCALG, MAUSIERIQ cc cneteeracce seat sce sedeovse ech toasesweenaonewe aio st tea aseaaeeee Canes 91

COVICHOSCODH Uren acve sear saasc canes ea nee ooo cote eee eset tnne wate ae tee ae anes 16
Sy beoanspansct coade snide cancocanoagesapdbsasnoceunoaacncbesdancubahnccosbunteécoscognctecaunees 29

Cysrornalamia SpuOVs2)) 2ecccccses tosesadousecen-konesa carte cencsncrduevccscacsaeie lene

Dasysaria Cooper, and! Grant: «.<..2s:scnscscasecveseasestcecsccaveevacconeston 75,77,80

Davidson (1860) oo ceeses jecect cee wecesesega ds consanrescncvsssnlccnsseosvsneeesvaevenuedes 93

DAVISON SG 2) notte cs rssce renee ses stuns heocae Poecnnce ostwpe eras cSueeeGne Teme eee 91

DAV IASON (LBB4) econ cee ccerecenecqcucsasersasecsave scvvorcuscesoreanevessrsnvaceuvaceaane 102

GLCONAtEnSIS; AUST ECIG) <2. .c.noccesssacecoseasst4-2otqusiscceske conesisccetasanen tenet 91

DICLONA Caron emer see creas sap ities nicene se ccucuenes eta et scat faa hene ot hia = Sane e See OTE
CE RAEN SA RANKS eoec eect <tnerasassccscsreccheavauvaessanuertadedieacnesueses 22,24,25,29
SP ivecniarosancen ent statan ves ane vonere snes enes cuneacec estes sederen sack ieee tere ene meceerase 32

AElIGAIMION S DIM LONG ver sccss pat cceceds saceeeeese tee new Rage eRe 81

EN AUTICUIAIA, WOEFDYIG! <2. c-neeecassescaseecuddecsseenene: 1 ane §,27,44,45,118

METIS AV CEATESTC UR eos tans ces crea vcsacveosan. cuuticessnesomtceensocece ce ecerteee ee eae 91

Pengo and) Bonnenbergen(1969))" .2.iceccacesccssesessescnere«sccasecuayrasee ee eese 9

CHAT KS (CG) id OF (0) (017 aa ee Br REE OPE CR ECRER-OICBCA ME AEE 22,24,25,29

Derbyia Waagen ...... 14,27,28,32,33,35,41,42, 44-46
auriplexa n. sp. .... . 5,22,27,30,42,43,44,45,118
buchi (d’Orbigny) ......

cincinnata Cooper and Grant ae
complicata Cooper and Grant eh
ef. D. complicata Cooper and Grant

crassa (Meek and Hayden)

crenulata Girty

HEN AUACHIGI“IN SD irccsssresciscatseetseceestece 5,27 ,44,45,118
filosa Cooper and Grant ............... Seaneassreoreees .. 45,46
Chap nlosa Cooper and) Grant ...0.<c.+cecceersccesven 2 29.44,45,46,119

informis Cooper and Grant .....
laqueata Cooper and Grant
nasuta Girty :
pannucia Cooper and Gr: ant
regularis Waagen

x 44
SPvascsscscsscrvccacsiavseesveevaessoee 21,22,25,30,46, 47, 118
Derbyia (Plicatoderbyia) Thomas .. -. AD
De Riveroi(1956)) c..-csc2csvenc-sssce «
deroysii, Spirifer ........ . &
diabloensis, Petrocrania ......... . AG
Dichostasia complex Yochelson . 2a
DictyoclostusliddleiAarriS xan. seen neseessnsscenssnesceneee ee aeesee nee eee eee 12
Diclasmau Wing cewaescstescesce se. 17,94, 104
problematicurm wordenseé King ...-2-<c.++scn2-c0nveneerencarncnsedseeaoss eeeeeeee 108
Dielasmella Weller . 108
Dielasmina Waagen .. . 104
difficilis, Meekella ...... 47
Discotomaria cf. D. Speer Batten J 22
Discotropis sp. ... 30
Divaricosta Cooper and Grant 84,85
Doescher; (Roi e:c-sccccsesncieacencwserscowcns(asiecoesasstineiae se seacen tases aeee era 5
ck Donaldinasp>ndets <2. .5--<<caseac-s«nseren4-sencnes <0 cece eee eeee nee teens 30
dorsisulcata, ACOSQHING «x.s.css00vs ssc s0acsisa0enane=sosesseeeianee nese eee 40
Dotiglass; RC; |PRED] | 2f5.5.-.ceccece<- co+.0es3e= +0 eee eee 6,16,23,24
Douglassand iNestell((1976)) i. -2..cseves---c-e- eemeseosnaavdecedavescee senate 10
Dumeril/ (1806). << sscccecseeeespceceare eee sceueesses dees <c ser aan eee eee ee 39
Dunbar (1955) bscccsccsccocse-sessssdesees -f2=2 scene atetee tac aa rane aon eee 74,102
Dunbar (1973) va. .ccaccssenseacescecuswessscavevenacsuconseea¥eavaenascccneantnenenateeeeee 10
Dunbarand!| Condrai (1932) poe -cscsseceseersscaccssaneeeceaceseeeeeee 45,49,57,84,101
dunbari: (CE:);.\GirtyOCO eli’... s.cec00cs-.c0c<0~s oeeeesncnnva ce sence tere ee 22
Durham (1962) cc. cccs-2ce-hice-acvassonsssccasae vss sesenniccustscnsctstant ee eae 17
durhami,, PArgfUsulinia rr. cece .s-aeerssncnws100=0sseeaesencnceeesass=aeeeseeee nee 16
DTU te as ep Ul eee ennctecpaacbonecoeeecrnanchcenadiann Pacaachaniséccncsccccccoont er 6
Dy orosiStebliss.:-ccccstcocsrecssoeecessescasnetscarn noses 14,17,33,35,49,50, 51-53
acanthopelicn. Spi) Sessaues-seosesceorss ese seems De aa 5,21,50,51, 53,55, 119
Dyoros (Dyoros) Cooper and Grant
angulatus' Cooper and) Grant <...<-.-..00-v2.2<sn.-asnueseeee een eer ee
attenuatus Cooper and Grant <<. ...-<....ssc2secsesecau=dsnax-ehueaeees eet
consanguineus (GItY)).2.ccs--sccnac2--=0ceoneee tev sc-seeeeesseaaae eee ee
convexus Cooper and Grant 2. .c-:...c0eor-sanencsanertsesss-aseeiee eee eee
endospinus Cooper and)Grant <<. 2<.....-0ss<censcaessse==-ae sees
extensiformis Cooper and Grant
extensus Cooper and Grant)... :-- -..00:.<2c<c2.c0edssadansanee- ase
hillanus (Gitty)) x c.ccccvcccccsss sveosase sas soecassstancndesaecasneneseetertaeeeeeeeeeeee
intrepidus Cooper and Grant) <2. <.-.<-.cen.s-eecen sear ante ean nee eee
Magnus Stehli <ce..ccssessccc5xs 6000 sense ececsscoseeeRe vet ee
planiextensus Cooper and Grant
robustus Cooper:and!Grant).......:<<.ce.-<-teceneetopess neon see naeeases eee
Subliratus \(Girty)) o.c2.ces. conceucssscsce cach costae satslne dene tees sean eee ee eeeetnes
tenurs), Cooper and (Grant .22-.. .2..<--200-eene- teen sseeeentae koa
transyersus Cooper and (Grant <2<...-.0.--escs-o><nee-sehs sunning
vulgaris ‘Cooper and!Grant . 2-22... <-<<0sccnae-neeeravenuaensann ieee eae
Dyoros (Lissosia) Cooper and Grant
Concavusy. Coopenand) Grantiyceceerceee eneeedeeseemeeseteeceeaaen
parvus: Cooper‘and (Grant. .....-.:.--.ss0s<<2se=0n0+e=-«race=re-ee kas
yvagabundus Cooperjand!Grant ......c.....<e.<-5 -<cesseeseseine reeset ee
Dyoros (Tetragonetes) Cooper and Grant . 49-51

auriculatus Cooper and Grant
giganteus Cooper and Grant

quadrangulatus Cooper and Grant
solidus Cooper and Grant ........ . oe
strigosus Cooper and Grant

subquadratus Cooper and Grant . Se
Diyschrestia (Grant)... .s.cc0e.<02 1 -eanceanes-eekecinceslanaasneneaece doi eeee eee ee 70
Echinauris Muir-Wood and Cooper ..... .... 14,17,30,33,35,62, 63,66
bella Cooper and Grant ............ . 25,30,62-64, 65,66,68, 121,122

boulei (Kozlowski) .........- 63,65,66
circularis Cooper and Grant 63,65,66
crassa Cooper and Grant............6.. 63,65,66
huehuetenanguensis Stehli and Grant ..............0s00ceeeeeceeeeeeeeeeeees 63,65
interrupta Cooper and Grant ........... 63,65,66
irregularis Cooper and Grant ae ... 63,65,66
BGT TAG on (SI E10) Je peeaereseeec seer accep RCA-e eOSee ACO ACOSCACON CR RED OSCoscCo ue 63
lappacedt Goopeny andi Gran taewesccscesseccensaaeecces send -at=eeskinsseaeeae 63-66
cf. E. lappacea Cooper and Grant ............ Cie 18,29,64,65, 68,122

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 131

lateralis Muir-Wood and Cooper ...............22e0seseeeneeeeeeeees 62,63 ,65,66
MUM Onan COOPER ANGuGrantiy ccsacsecosessesexaastereeeteretoeceeheres es 63,65,66
ef. E. liumbona Cooper and Grant ...... 5} aoseco 20,22,26,27,65,66, 68,122
Pap nda © OOperjcang Grants. ceceecderssecceemcesns- see teseteene ses Mate 63,65,66
GDUPITI CU (\WAALEN) frais sloise vals cstes'sire cys card vubsclsivaee neat aecaehee emote ee ereer 63,65
Pas COOpE ANndiGrant:ccs0ses00n05cecesassacusceetecetsetessacee ewan 63,65,66
productelloides Cooper and Grant..............sssccenseeoneeeeeeeeneees 63,65,66
subhorrida (Meek)...............0.0+5 63,65,66
subquadrata Cooper and Grant .. 63,65,66
venustula Cooper and Grant ... 63,65,66

SJB snc cocetececesemmbos oncosscopesonceconcer .. 65,66
Echinoconchidae, genus indeterminate.. . 74,122
Ectoposia Cooper and Grant . . 104

BE AC Olina ver ocrcencteeec caceseess SLO)
Cutucu Mountains.. RY.
Ouitomwi aeeces Sek 39)

Eldredge and Gould (1972) . ee (99

elegans, Pugnoides ..... 785

El! Horno Formation... 12

ONE eee ee 36

BAR ULN Cimon eee cece scares s nasisnilenuehiey cents nloavesciene 36

BMIATFEU IM OTEN Ue oscars faci nccirdenccenk cs’ sxncsee Sve dus wacansoeg seeaewevaemav ans 62

elongata,

PE MOAI ato cic pin lon ss Sa apinivus op diiussnn scsi se SoanemeanSnanncVannusesmhs 82,84
ICR ANTI MEO e aeRO stats sce cd sx cea'sesksasensscoaccspsueesielshsaeeatbsaceisseeavess 109

PLETE I ELITE OOM DIO SILO ieiatee Satna sracie ca an culees Grace veces sennds sine cc-wsevhie oeeeee 96

BEBE RVEANOURITIONDEL I (952) ccs as ores susnasesssconesiensuisokpacce<ncssaecamnse aapuax 18

BOSELIUS SV OLOSE (LIN OMOS) osaics-s-aes0s.snsenescenaeeacsicascearasceocerasevvassas 51

Samana Newcastle-UpOnaby Ne wes cenaecncesseereee<seereconene erence aoe eeck comes 6

BMRA INIT (L935) etech ce Sarat cas oo spa denne ta dees oss Ses seeee boa satnasetearseoee 10

PTS CC OMDOSU Dine ren senenc oe Bus cen ciens occseeslesacesiesvsscacgeecduiensiieeas sesame 96

PMRTUPC ALOR ETESIELOANE 555 as chap asendensielss-caiuacslaccee> -aseaieecepacesslenserukccaue 49

Brdtmanniand| Prezbindowski ((1974))......0.5.cccn-eveccencneeccsnaeessscnnscreeenes 18

EILEEN Ror: ROMA Soden siccas od aaciraleniinaestiasbiesauizeenbes aeatasbunesecan 36

esoterica, Stauromata 2,3,4 ...... §,20,22,26,27,50,51,52,53,55,119-121

Euphemites
MECMISULGATUESHEAy CHLOMIC | erckessqcssaccea= serena caves sbeeetnesaceecteossneseea 28
EEE CEOXIUISITUESMIOCHEISON sivacies vreau vdacincsestcescecastsusseessansevaunmnasne 28

( SRCUELLE, (HELPER AES = a aconcanoncacoacoccoce-Cadncl-csea- Sea aeaeeanemasoeee 40

BRISTLE SH (Cla ME UDREIMILCSS con cseoscessenancueassoceesssecacssrenctseneeaeseese-c- 28

PERSONS CD YVOrOS DY ONOS) <> .ccncsscasniuweceséunasacenen0seseservesteesctngne+ Sl

BESET SUS LDV OLOSH(D VOLS) herteceacencontoeconncsetisesns sapaaecseroaeessaaseanctesnsee 51

alafer Grant ...........-..- : ay OU

fasciger, Spirifer .. 100

filosa, Derbyia . .... 45,46

filosa (cf.), Derbyia . 29,44,45,46,119

Fischer (1960)... 35 (9

Fletcherithyris Campbell . 104

BOUK (1962) .......0.50..0205 17

PROFAICErAS ....02s205-.00 20

formulosus, Neospirifer ......... elo

Brakes ef al. (1969), ............... oo UO)

mmanciscana (alft.); Apachella ...............00see.-ccesesvee & Biles

MEPLRIILEVISIS WE ONUSIGtcctece ress coccre tierce ct necuecente ces sa SS

BEAK GIES recess a ache cect serine cee cee iecuccuaen as sveeast 10

BEETS: (191 6) perce. cectessccesstocesecerctesceccnscsserseraaeraeteccosoutecsstsemsatoes 102

BARCEL IKSH (1924) pete poncenoe renee rece neceee oie an eeree ee 96,98, 100, 102

BAEK (192 6) irre ceene cosh cocwtu reese cceteeec eta ceucsseusesevcusvecectuscesdisners 100,102

RECESS (L928) cece seeeveccsecccerssvsctetettcs cases ecvensvesnsen eens ineee ones ysuns 59,70

“rail k@ (IEEE) piesa eonaadbs sa cugdackd eahoonct ten eecaade ne Rasaee SecA CAE SEE er ee eaEe enn 77

Beer anidrandlietza (Oi) icceeces cect cbesceesestcennccttee secre seeca teenth ees 8

BOTS HRV PMU [IWVOMUES | rcsccecsssseseseetiesscecesosesseseseesonenee 6,16,20,23,27,29

BRISTLE TA, ALEINOUSE #0: coseece cadets sesineseecci ons dieoeee comer creases eee 100

J CSULTGL aagSSSEISEEG RE Seo TAP BE eR EED RTS DRRUA PRE ae 10

A GHT@ SiG le seeecesotee: coc cc co pBecor PERE E RECUR EE EEE eeper PRE EEPEEReoberete rie cocareoan 107

Gaptank Formation 40

chy gce5

Pencil AL AN ROMME SANA alo noe c sce occ eon thee eee w eee neo ne TR 5

(CEI ICAT ATES ren entre ceaonen oo cCU co IDGLCOPPCCECLOOCDeBOcT DC EOOCOCE ERROR ETE DLP SER rE cre 23
Gemmellaro (1899) 98
GeolopicalliSocietyiofAmentCandccsicaccesneeeiascerssseattacoceteeesensecene smectite 5
(GOTT OTALCI Ne econ hector oo cn ITE none CORCERE EER RECACRrIe ORR RE RCE REA CECEREEEe naccnecn 96,97
GeOn ee] 93D) Aero riee cwitie cenioeie cule eetteauciclus -uvese serdel sucvamaceees cee eeeaek « 98
(CSTE TaN esc gcc bode DEO BEDOe cS COAR EE DEERE CE RERCBDE SnceHOCURE Jac aacee ScucEBHEL eA nbeCRESncad 57
GerstembonmatlOneencscacers svecastacedievssdecusiser acces ee teta eee ees 66
Gerthyandiikaausell((93\l) Weassensensmenestieseccsesncencasactec ascent 10, 13,100
Getawayuhormationy <csccivsedsuesesduiiavensssscosacdedenoudeesscse- dente ee eae oe 14
BiganleuseDYOrOsi MetralOneles)hideacetesde komentar ote tease teeta te tees Sl
(Gillediat Steb lis eesiecsesavcecne sek sotesvacnndesvsesesaecasaiedsueoee Tae es 104,105
(CTTIOTITNSCINCLT coneae ep RC ONCE CCHORCECEOORCEACEE EE RRCEO ERE ERCRC EC ALOReRECLGLocELESEDOCULG 11
CET AUNITES U2) iteceere der ceetere rc eeceeerrer rec eee 9,44 ,46-48,51,70,78,84,91,96, 103,108
(Ginty4(1920) x. Sei ssees sguct dus ccwsrcads 2s Wimees v evee stead. asc sa ae toys de 101
GIR E G29) a dertrseara stares aed oe cise tetaslns su udsnah eeweavorsaasubeser ea eee eae 49,51
Girty (1934)
BintViM Wie llerellG geoiaccstccausiteadecaroriiecwAidacags acd uaa ee 84
Girtyocoelia

cf. dunbari King

DyiSPh wevasasteenes
Girtypecten

SPiveceeccnccaredecunzevesn dee
(Glabrocingulummsponnde tom aesncddeceses-eienseccasoesenendence eee eee eRe

Glenister, B. F. [BFG]...

Globivalvulina 12
Ses c0 500 2c0dgec650008 99000030 SEC ECAR ASDC ERRORS SaOC EEC HOCECMCbe HHEmOSSCHIRO AS aADOS TAGES 23
globosum, Aneuthelasma
PlOMerOSa EPUSTEC aati retes sca sednentet isu occene oo hegeta eee 91
Glossothyropsis Girty 107
gloveri, Pegmavalvula ... 24
gloveri (cf.), Pegmavalvula.. 25,29
Glyptotomaria sp. indet. .. 029
Gly plospiratspyandetay oes csae nets selee soeecocaes seco eases c= ac oe eee One 28-30
Goniasma
Soe (WC bsoncasbuascaccnssdantonusoncconnonodooLOneoncosononden 30
Seb WOsoccoaanoas 30
Spindetizapee.cestee ee 3,30

Gonzales de Juana (1951)
(Gordon Mie ere seeocsnseecaace

Grandaurispina Muir-Wood and Cooper .............2+.s0.ceceeceecee0eseeeeeeees 70
grandicosta,
De OIL) ec epeP per epOp oa serCRaOONE CBO EECRECEDD Set OOE Ce MoGUSSeRee BS EEE CE Ducacocek Eeone 91

5,27,30,76,78,79,80,81, 82,124
7 ...... 21,22,29}81,82, 124

Spinifrons
grandicosta (cf.), Spinifror

grandis, CompoOsita .............. =e 85396
aGrant yy RoE) ces scccnn cree . 6,37,55,62,63,97
(Granti (1.968) \ieeseeessenee ee 62
(Granth (974) eeeeeee eens bs 37
Grant (1972) wesc eet act: seatcwosaves oases teunecsn sega Se. Woche eee ee 57
Gran tiGl97 6) i weeesecerer seen ee eecweuese 25,36,57,62,70,77,84
Grantiand'Coopen(1973) hice. seccsesaceedececcce.ccesees -. 8,13,14,17
GlaNtOni aU BION Mii s. -en-= sexe ecewesscuceussecuse tees -.. 100
GraygGh840) isi eect reac en. cocn sae ecancoe, sume eecoe eee 62
Grays (USAR) eoees csiwse ante tkenaseoaserawaneneueceuiantes so eee . &4
Greece 62
ignegariaCollemataniae fons cc.civscacsssevereceecsvieetee he 84
Grinnelliandi@Andrewsi((1964))pen-sscee cern ereesteceeeeeeeree eee = r95S
gryphoides (cf.), Megadesmus 20
guadalupensis,
INGophricadothiyristnes::..2.snccccesen coves te eeev vests ee ee 99
(SQM AN ULA AMI. sacle seed ott vane cea eee ek ee ee 99
GuadalupianctawillianisteKang, sauc.cs.-ssessaneeam eee eae 25
Guadalupiaenisprrrssccscceaeckececcsccvecueoue arte oe eee eee eae 24
Guadalupiantstrataiee cc. scscceccssecestevececuss.u ss cuseeeatean ete eae 12,14
Guatemalan artee eee ne ee 6,9,13,16,48,49,62,63,65,66,74,76-78,86, 106
Fuehnietenanpoyscncesrecss te oAonusdee tates suns neeasss tee tee eee eee 9
(GuiZhOUupectenaspree. scese ssi s4cswetanenlixsisnadovsnseeete eed eet 29
Gulf of Mexico
Bartletts Prous hy west cee yore dias Gace iva tedee ee tse RIE 9
(GaymanRid sew eree ce marae caer cee stew cM ae cinteseesistteh ee ee 9

(GypospirifersA Coopermandl Grantycercessssuteeces tener eee eet eee meee aes 100

132 BULLETIN 313

ELabich ty (ioe) merce carcrs a. se netnte ccte aca: cesca sik sxc wen snes shits suet enc metane reese 33
FL QErLOGIINUSS SPe cannes cnesaesvessece roses sanwerssaeversssnrinieesncmrlsinogtssnmansin sae 20
all (S52) eeepc e<nsscccnsccpesewcuseonss 5
IETS) cenocrer oahce nee sngctene bor eeepeeaceeCoobeoTnceccrodaccpsesenpsc SeGcoonagr.ooc
IS ENC GR GYD) Cssisoeconcocancece
iBall atayal (CUES (A) meeesemeasonccoscoce cocoecnocercoren-anacading cosdcerce ane coe 40,41
Halliandi@larkets93) jn cc. ede seenacccn vere cnen sean ede neers aes aeee eras 88,100
IS Fai ter (ORE IR®) ecnceo se oceronce cba ponee done dopaccbocbobonsacncnanescacoscossocconmecncoqneoR 8
WCAPPGI, NEAUSTEME CN een sere 2 danse sean sleneiieanshive sane siapanls«oeeletelan sey apir ees 91
Haplistion cf. H. aéluroglossa: Finks ......scccsccccsset-cnneuescoaeesnenncmnes sen 29
hapsida, Composita 96
Haydenella Reed ........ 62
eavandew hitiniartl (960) lsmecdteecwcs reconnect edenaasecisnaiieennanlysuctretsacetrarete sites! 11
FE ICELE HAUS ot acteemecha ce bebop Se EEC DE REe-PECECNOC FC DCOCHoUOr-cocacererecerneerei-cssnonnces 21
leaked ero peated SSA (UIE BTA) erenecononc-nopnacrinnoovosenaardeobos-oocecoonapersanciaacan 10,12
[RIC IIE IG Sesuoce senccponcecc ue Heo saeer rope eeneore-DaBreMntodninetsicoreccmascecechsaosdsob<sb 6
Te ALA ARTE Ug? \WEETEO | Waseaee BRE eeoe today Ecbee osrOncencecooAnoeracceobbecece siocpaacoec 104
IRIQSS TRO) RPE MTS Ns aoosemcotcanbcosecchase coop sac HOODESDOBEOSUABOBOD HAUDObOREOHOIIOIO3095 14,99
[CRSOTGIGS (RTITAGRA comopcecoticeccoeececnose coor enonenchnpareponseope co sea0dccansocee0005 91
TE EEAATORTEN Ain te pa snesnueren bocterE ne Ocee asco non AE Denacnde ben O-AAREEEEe Rap Eso coker 2000 55
Tele relaSiMaiGinty, seusscacsuerckcecnsecsereceteec ner aner ecenkcsnchakiceecinesoabiaieceecira 108
IE(Sti@r (IEE) ceccanoronver cacoocnoneseongecoTacsohaneaoaboqadhoosonapecbesnoncdbbesdcsa 11
inh ON Gills (WISTIAD cesesccccosneesacosncsceainodocedoooopanoncsoadpacgakusoneaDAcicacapoN AG 8
Ie Olin (IES) ccsesacasoboccasedcensncecopbacecoceacsseeateonencacand scaspaas5osouagecqCud 101
LELGTATG) IDEAS: (UONOOD)) sobocaskoonoonosoonconsoosonnooconppoomacdeependscd iooccodta 51
hilli,
J RTIICTIOS soneacen icp ageDoe PCOCCOCOBEEEOECC CEES COGE EOE RODCEIODAS DCOOGEM ETE OONGOOHDNE 16,23
STE PAGINA’ ccaccecaner crac’ a cencansemnobenbdnsnChadoarnrcoseaoracAvesbanceon 300 103,104
QEEIITE ceenesoerdo-aconceoconndaccncocponsennusseeanscaroccsrnacasomanccoocmemontiascs 103
IIIT (CEs) SS DURENEL MAN siete ace sninara eels selcejeeence cee Ce apanoe 21,103,104, 125
HIT SULG EL OLOIIGHAPINGI weeaqaeneedcaeeccsscese ne seneeeieel SF pono PAPA AD ile Wed
IRGC RUIS (HEAD): ssaccnesocaoacacdensoeacinos dnsagnonsqnobescaoacsonaeomqdsinscosaansgenasGanous 49
TBS WIGS (ESO): nscnanssaseaossobecocecdonnndcoadcascqonepaLcodonto sonooDSnoNoDagAOSECaOIUK, 9
Tee AANA Chile, “Satcnpecepas-aseeneecencer co BeacsnpeceecoSSD ent eaoseeedeoo soa Ececm 21,25
Holotricharina Cooper and Grant ............0..:00eeeeeeeee 14,17,30,33,35, 70,71
insutanGoopenandl Grantieesssseessos.cessecneseseeesens SS ssouns 2 ULZAl, ee
Sinerer (COmyar ENYA (GHENT ccoacoréceaceciencnseanonobosootcccandoosAsarscansazssono 71
TRAIT TO NATIAGR? asgacceemancencdecopccooce decpoduaonoasanaAecancanancossne Sanna noeo20s00 72
SPPsp Osa ieee aera eae vcs ceecaadacsscvarecmums dsbacaae Sites 27,29,30,71,72, 122
S78, Ll oceccoceseccnscocneethookeaceodaadaccncoos cnco. chase Noo conoccuMbaNceBIeccannaDece 71,72
OOVER LOTS)! Gescnnsecer ves see cuencasdeone<-aecememnecsunersurersanecsencaens 10,13,82,83
LOOV eI (UL97Ga) ie oer ove wns extece cuciat ss scene erecncssenseesneess wees 16,31,32,33,36
FIGOME TAG OO We nein sere facet osrcbacxtcrs ts eset i eetesaiiansinceenens ect raneereeee 8,17,31
iHoskingiaiGampbellic-. cos. c-2.csccsecnecs ss ap accieacsa Sotedauenans sovaasxerteenec see eeees 104
IO WaT RY ie sreceetncnsscneanessesudeccedtchecesntscVscn secs sc acessnasceenesuecueeasscsetereee 6
huecoensis,
TMS CUI Bacwances> copes das cseeicatsensnescuceessesscsecssasocdesestsseweteecs torte eoeees 91
IMPOSE), tase cena temas as vecee a asian nak eane sven cae atsccrabacne a iewe=sexee eer ete seen
Hueco Formation ..
TAA OVO AGIO CI Os VRAIS: _ peeecoepscneacuonsacocee<enechannescroncescodcos 63,65
Hustedia Hall and Clarke ...... 14,17,19,20,22,25,27-29,31,33,35,88, 91,100
ampullacea Cooper and Grant .. ae 91
Bipartita GUty civsi...0s.0+--5-- 55 SHI
catella Cooper and Grant 91
cepacea Cooper and Grant 91
citeria Cooper and Grant... 91
compressa Cooper and Grant 91
connorsi Cooper and Grant... sol
consuta Cooper and Grant ... 90-93
crepax Cooper and Grant 91
culcitula Cooper and Grant... 91
cuneata Cooper and Grant ... 91
decollatensis Cooper and Grant....... 91
aemissaucooper and! Grant s:.c..1sn:ccsecseonceseses ere mol
glomerosa Cooper and Grant .............c0cceceeeeeee 91
grandicosta (Davidson) ae “5 SM
RopalonepopermandiGrant) a... cssscseossccsecscocuneasccnasener cee Pree A
HE SBEVINISMIGATIN Sts canaesendsiwiess- sci iss easevanenea neat suseranees oreo TEE 91
huecoensis King Are sadoewebsccasva ste seavau\es a CPaOTErE eee 91
hyporhachis n. sp....... 8 . 5,21,24,25,27,29,30,88-92, 93,100,125
WiconspicuaiGaoper and’ Grant c.csccereeseetececdstcntees ieee 91

lusea\Gooper/and)Granty 2..-0-.<s0scs<ccurserev ess ot secen bees soe>serer eee: eeeene 91
narinosa: Cooperand!Grant:,......-.91,-.-5.-». eee nae 91
opsiaiGoopenand! Grant, t--s.240-ce--asansnencaniies seceeaes sie aneiecsiae eee 91
pupiiias Cooperand) Grant \-- 2. .nn-ac-<cecnn sand sseeeresans seesee < aeeee ean ena 91
nupinata | Cooperand| Grant ...: een -searaaeseesasaieeaenaaaeceh sear teee eae 91
samiata Cooperand|(Grant... .......<:-sc0sn=sa>noenorehesseseseesaanene eee 91
Sculptilis, Cooperiand Grant, .0...2scncansetspersver<ceees-be<haaes Hence 91
SIGUUMIeMSIS \CRTOMIC. copse c--accqnecseaeanyssnasxaneenensunas nee eee eee 91
spicata Cooper andi Grant)... acsesscen-ssncencmeieseetidsars seers tanass teeta eae 91
stataria: Cooper and IGTaMth oo... seeeneneicanoacehenersnsercaneehi eee eee 91
formed |Coopensand) Gramt.< «<0 cs -s<<cneosenn-90) <ehmananceranaems sees eee 91
trisecta‘Cooperiand Grant, -<..<0.<--eccersees-ein--eeaeerttensessee eee tee eee naan 91
trita, Cooperiand |Grant..;..2..0..0cct.c2sc-0s--+>50c0ssendceest eee eases eee 91
SP eke eacane et zad et sa tea sesaene sae Nee heen vances
Huxley (1869)
hyporhachis, Hustedia ......... Bie. §,21,24,25,27,29,30,88—92, 93,100,125
Hystriculina Muit-Wood and Cooper .......2...0..sssecceeeeceeseoccssnecsennsens 68
TO@ZINCU9GL) coe ecw ees vate e = deseo eee sdeoes aecnces Ovect cent emacs eee ean 102
TMNDriCAlAy| COMPOSILA! |. vecpuecscsseon sececc<recovsscesoneenctie: ones Rretnaeee eee eee 96
INCONSPIGUG, TAUSTEAIONe- A ececnncense=<cendnercae seetieecee=ct ane eee eee Reem 91
INCUIVQTA, RURATIC, Grececcvesss:: sees <ccese carvan: steer «scecccns Cpe eee area 78,79
indeyitatd, VRQUGISDIMIPEN lo. cas ne vecasseceeeseees nce oxte ee dere se eee eee ee 70
INEXPECIAIG, (COOPENING ee. seecdseeessensecenseseeesnewe 4 ...... 24,25,57-61, 121
Inflata, ANCMONAMIA! .c.ccamcsseeschice duce ce-seessciscceschienscsee senhe seen Ree eae 67
InfOrMis, DerbyiG! J2..:cices<:-2e-snonecaesvoreccsetei ste qaseaacoseh ee eee eae eee 46
PIN OMNIA, VAMISOPV OE (eawcn ec. acceeUsecscccsen eaves enaessedeasseaseen i eeee se enem 30
intermedia,
IPQUCISPINIfEra” ..2..ccescsoussnuscaeesccusccas tees: sentiteactet\seeaee Ree eee eee 70
RUBAN A’ Seacancuce«seereteceate eee mere (isesean 5,22,27,29,76,77,78, 79,81, 123
THLEFFUPt Gy ECHINGUMIS iamees seen onnenenes ere cae sn 2s sess see eeeee sees eee 63,65,66
InfONSG, (CleiOMMYridina’. .o..0..2.-0.>-.0-sc- ceases encssnseatenase stants eee Stee eee 94
intrepidus!DYyOrOs) (DYOLOS)! cessccnss sec cence ener eros See seco er ese ee eee ee 51
irregularis,
Gollertataria™ vai s.-c. see cesecunessteseeie side nat eect teveest sendenct coset eee eee 84
IECRINGUPIS: cdecac cause clase oeasencas de veseked cansene «seas oe oes Eee eee OR RoR 63,65,66
Itaituba Formation” 225...2.-i...0.cc- seen eecesevsceesecesscaversseecuntedeeee eee 10
IRE Tovey 2t( GIES): Casesspbectincrnnossodaacebanbadosnanonsedocosuctsnosccasaaaanacconnccnss: 72
IvieSi(18611)! wiccsacsccec-wccee cncecccessoe-cccccesndeoccsccenseceeen™ Seetn eee eee eae 78
Wvest, PEniCulauris: cc sic cseacace uses ceeescaeteen cs estoeaceeacen sete eee eee 76
PISUENSISs ECRINGUSIS ae x ctecen= save enon Secon teed apne cee n= ee nae 63
Up 301 Ss sapeacecooraadac so Eccoeuee bec uSnEReEEEOLDCOCADSnOGDODPEnGoCOaOHGanamoSoancadcoanat 6
Juresania’ Frederiks: c2.2c02s-cnecce8te soecaceessscceesse22sceeecntsee ence eee 17,59
kaibabensis (aff.), Straparollus (Euomphalus) ..........00-000cev0eeee serene 27,28
Kai babwRormation ccsrecsncccestcesssnsescaresatnesease seer asenek eReacn ethene
IBIS Sco cococconcaacoe sno co sponoAsDSOoSOShAD wnocaMOAENOOaIOOAASBASHS AAs
Karklins iO; Wo [OW Ritecccieccsesnccesscarcecacesnedeseaneoeneee
IKeehren (1938) mecercsseccesacwes <lose eeelte seeineine sciatic

Keyserling and Krozenstern (1846)
Kier, P. M. [PMK]
Kong, ROE (1931) een
King, R. E., et al. (194)
King, R. H. (1938)
King, W. (1846)...
King, W. (1850) .
King, W. (1859).
KRYA QUE OFTILS) Clie cn ee es ans tielaensine ani lals se olshrsiokin rane eee Senseo eee eee
Kinishbia

Kling (1960) ............
Kochiproductus Dunbar ..
Kochiproductus? sp....
Koenig (1825).......
Koken (1889) .......

KO ZIOWSKI (194) tices. nesters cots seh eessee naa meGnu Nitra pseneseneeee
IKOzlOWSKid\ sc.csvctecs csecstec esti eac ese cossoa ress seetbedesst ceesnas ssi ieee eee

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 13

STAD IEEE) is sycaseeniece nee: contece en cco oecosdeeecor caer rec cc a-oscehc ne Gocopccoe ecco 53
ROOM TERT SF eaneocacceeot oop noseboe009060"000200007000soqx¢bun panna sngnEemncoco 70
PERI TITIN L949) rceracne testi sdeveceniese added doves ssesuecessomencunetencerssncee rests 39,84
BING Pt (L988) pocuvetsccacdasceu ses eesdnuseetscronsceuces cee cdeneec wuss scaemmcecesdecnencse 11
BUNOF PINE A IVANOVA <.-c.uceccordeawccedeascnorweesossvesstessess 14,17,33,35,72, 73
PESCLLE TESTS) (WWW.OLENEN) lege eaeetictee Ace-vtcoddecce acres scaek ces see oneateeeectessriese 2B
PELICION USA CIMICIMCE) Wcaccaeccusensrerdadataconete jlo acantdaconee sovasusenee reece ce 73
PHOSQIHENSISHLVAN OV Ayeaan ce vcceedccsc cs clecesevcosdecsdeveesacddtedce-teeJscacecnacrencce 72
FREI ATTARS (CRYO SO)” chcccereccbeecocthcheee cee cee cer ct SoccACbneb-poce S800 s0000086 73
BEIDISPINOSA) (Stehii) szevsorestensecantacdserddyacdeac nc aeesteceseensaveaereesmene ea ees 73
RaoUs tal COOpentandlGrante crc: -ccsse sca: entrecteds we ce etree ceases tedcccer one 73
BMAP EETAL ANAC OOPEN) be swonsre sv tse co dacs onere ex eeoeiaedltddeeeveces3-eeeaterseasacs 73
RHIAN EMSISH(KING)) cncecesvseeavauserudewucvevvavesderecsssdecdseeerestcerouterstes ts 73
Bement Cooper and: Grant: : 1.020 <cdssedadedeceves sae sad icone rene sataacatcece veneers B
umbonata (Muir-Wood and Cooper) .............2..06...0cecceeeeseeeeueeenes 72,73
ef. K. umbonata (Muir-Wood and Cooper)......... Greece 20, 22526527529)

72-74,123

PUA EAT PTO KARO V ing crite eo aale ve wo awaete aware edoes teavacc vive decsudeevietoneeres eottses 104
1 Li AMOS OTE Sos eccecee enc DS CO LURE EERO REE EO cic cope OCRE Ere OCCREC ERC RCE CCE 22
RRNA, JETT) carpet endennecececco see c JncrE aoonan NS PASE ne NBO CO RScaEcOe 63-66
MepaGedi(Ch:) SE CRINAUIIS) ....2.---<2--<0+0-s0ese2 0-0 Sipecseee 18,29,64,65,68,122
SESE, LRG ENTIT Gheareeeatncbapeace scons acca gONcO One CONE REE POECEE OE RESECER CES 41,44
MEMOMUNLANBONM AMONG 2-6 aces acces ssqcniicsosxcacsteccvs WaGerte censuses crecessececne ss 11
REE STS ULONEIILEU Gacca se nclnagcitesaceteaciorselskescsies Cobenesccdeecsiiesedepacesss 73
BEL UISE CHIN GUIISIPocoseecseweiecocaececss aac seGascndecstcenivasewsnnessreas 62,63,65,66
SMILE CUCIS PINION) 0.024 3. «2 2ecianencnceceuvecvesssousececsecetecssaatusranosans 70
oS. MEG TING eecia lee hese aco cBOR aL BEC EEE CLEC PaO CReOEEr ROCECOLECRE peace Comete nace 101
0 SERGE UL SY oe rns encer ee nse seRHE ace ne ScOnCaad IENEANCpeO-eCC I GOFOR CER SOUE EO 18,19
mec. CS. [CSL] .. 6, 16,23,27
1 32((IOWS))) ere saeracas 16

MEN ALCBHOLMATI ON iy sees c-s8en ooccesceresscensqcescecucsevesauvecensacecceeausecstessecess 9

Leonardian strata ................. 14,15
Lepidocrania Cooper and Grant .. bay SD
Lepidospirifer Cooper and Grant ............... nee 00
Leptalosia spondyliformis White and St. John 57
Leptodus Kayser ............ 83
Leurosina Cooper and Grant 49
Leveille (1835) mee 93
Licharewiella Sokolskaya 41
Liddle (1946) ......... 11
liddlei, Dictyoclostus ie LD)
Likharev (1934) ....... 94,98
Likharev (1935) .. agp)
Likharev (1956) .. ... 104
Liosotella Cooper ............ 67-69,77,78
Lirellaria Cooper and Grant ween AS4
Lissochonetes Dunbar and Condra .. 17,49
MRMBONA, ECHINGUTIS .......c0000ccssecceeecenes . 63,65,66
liumbona (cf.), Echinauris .............000..04. DS cen 26,27,65,66, 68,122
MMEIEAENETIOS TS, Cul te™, Se tee cca Sag oss \ciweasevetecepescsxseawecs duteceia ove 10,11
PERMIAN CUNEO /TLISI AW oacack occuodescsscac«cicesswsiiee isan cosets eiede sees sep SO
BURRS ZC ATI OS) (1 OD) Meese wera ce cea ce secs Acwe Sawa cutde © vce Geese «deben one neeoencl 9
MEEPS SILICA EVIE PPT is oie hc ace ois taes veka ees aaueen codes clans Sieise <eee anaes 28
REMGESRIS CLLOLAS) ole er Se tce ck cece Sas waies dnisioss ane cveckzsvicsveuaneetestvabuipasncuse 20
SemmCiEe Ls PEMEUII(TCLLOLS) |... is <= aes cewssscssis>eaaveeenessoavenacesdsscacsecee 28
SeaEAIORE FSDINOSGIUNCHLOLGS ioe 5>ss<-sex co <evess teed svclssecevecasseessseeesatt 27
Eee Re AE inte sooo cides ssvsiasceviiaviotuevuss ar 26,29
RMEIERESECLI17 AU (SCE MII) Waste Ace SOAR Cc sees ssh ceeanecccessuseccesteesvosmeree eae 104
[8 TEVASHEG EE? coensanaeca st coo Reo EEOE DOS EECREEEC EEE REE PEP RCE TERE Sc eRERe renner 91
SaIaRtreAKAELATIN (OL OA) cts ceca een hee ae ee RR Oe eee 95
APFIEIT CAGES PY Sho, te OPE S Shrigi SREP Sos os curses canewesicuxnscste oes ee ee 27
REM ABE OL AUONw--cbahecres. se eee races noe seeoeeesce cose eee 9
magna,
LTLLATEUTIS sp aha sa asescose eo SRCO ECE EEEEE Eee hore er ae A eae 63,65,66
DHTSRTORDS Petae a bee a Socio scene Renee Ree Be Berean to 81
EE GCOSTO! OP ELOMLLISI Atm ree ee, eee te es aee ake a sistvevcklace on edeunecescstueetees 86
CAA COKE] Aaate eaten tree ner ete cect secccsesswsvicer cece noose net estes 48
MRIS IFELL ME. TUE CTSIITELP ETC poco a vevosuanen vest bine os ene'st sec ek tenes ashe wen ome 70

magnus,
DY OKOSACUDY OF O5))) ovarawecenencececuncwecn: vaveee ieee dood eedsnecdeesesee neserees
MENOSTELESiee. sastadoe ste
mansuetus, Neospirifer ........0..20.00000%
Maorielasma Waterhouse
Mar cou 858) tears ates saci van cites satire ca deus cheeeccckeescareaele
MarviniferaiWaagenttittecsccsce: trace: stceretie ce cooee ce eteaee cece ee aese teen eeee
SUBIGEVIS KAD OR eee aoe COLLET RET EO
Marirurnilag Waterhouse tes-1.ccscose sees scaaescsaiesecenderetcsacereeeertercars
Marshall MCOllermataniay sr Rice esses eae Tee TE
Martin ta) Ce aie cite detec ss Sates ve hee caniev ena eadwene toveeaeee eh oveuceeenauer doemeeet es 5
Me artnB ey (11 DGS) 0 ie es seh os cavitn weeete sen ceeanceetstees dencter ieee 12
Martinia McCoys secon ccc einvaetireis eat vit tate vie ged sae cette onda Was 94
MartinothyrisAMinato! costs Seseeo ree aera 98
Martocerasisubinterrupta (KTOtOy) i sceersseceeste ne ee eeeae aces ene eee 16,27,28
Marxweelli( 961) Masse 5s ortrate weve oi cea cLeeniGaeane vosh ac sedeeemonce cs sure rceteteee 98
McCallie pesiwed 5. crusciwe veer eett tear ect oe 6,37
McCoy (1844) eee eed eroee eters ea eee dan ee 92-94
Mickie (1938) ceases Faeroe cease aaa esse vo sncectucivcstuseeecs over 73,76-79
mekeei,
IRENICULAUPI SIM ec tac se ce seco o ase e ren es Nees de de Ta Uate eee te eee 74-76
IRUQ ATIC: TOseee ee viccee cvs cavs sooace Saas da Rawaestsecan webvevesedeasesad see sdouaoees 78-79
MedUANENSISIAOK Ani ella. mee ies Seas Re EO 39
WE CTH ace an Are AoC eCOCEISBEE COR CE EOS ECICCEAC HOLMER COREE EEG ROncro SoBe 63,65,66
MeeksandiiHaydent(i858))areresscceacascnactcesetseeeanekeenainescsececnseeeereeeerees 45
MeekcandaWiortheni(lSi7ayeiecscs.tccns secoseraaareserere ride dons ce codecmemdaee saaaes 73
Meekella White and St. John .......................5 14,17,22,23,32,33,35,47,48
AILENU Ata i GUt yee Se wes Poets eae aa TET ETON oo noe daa Stes ca aeek ART 48
calathica\Coopeniand'\Granty (iceicetessesecs ns eae caste 48
CF RET S LU ce oA B Rhea pec oder pC DEORE CRC OREDECISCEC OR RCODER EE CROCE eoSece 47
magnifica: Cooper: and) Gran 12... 22e2 002 see2eecetaececuacensescvedesessteacdoetiee 48
occidenttalish(NEWDENTY) iceate recs scree cece te eee a eaeree eon ee on ert aneo tence teas 48
prionotasGoopenand) Grantie: <.cncsces troanseneoese aes eeee ec eaeae eee nese 48
Diets LONGING socdeacoobocconnestepseacadeos 2 ...... 21,22,26,27,29,47-49, 119
SPsheaiseisaccesnr ects see ece een tockne suse veuicrenversadSedevererstosecsevesserereceasee 48
Meekospirayspmindetetevessssecerrtrcccsternnc eecenete eres Stee ae eee 27,30
2Meekospiraisp Hinde tisvzcle.s set -vecwss acseae os 202 sachet sa vans ssosessaceesd seven ties 29
Mesadesmusicht ory phoidesme --tecsseeeeee eter eee 20
Mepard ier alin G97 Iyer. eet tenee ase aces anek race erase oan naaan emote reece een nee 10
Moenides 5 At nsitie cose tiscte aac erare sae de dawe usc oes Raub ISTNOnda a aoe otc seaee eemtee eae 5
Menke (1828) erent te Seah erases vas sees eee eee eee oe ee 39
Meridarfacies sere tacccsiecds rent te ae cen sa gie eee eo ee eee 12513
meridionalis,
POST AG| ITU cea ee RAE RCBEB EE COnCE CBSE ECE COC DSE Cone ESE DESCOCCER CES REE ES OEEC CRORE ASABG 73
Productusi(Dicty Oclostu) Weasssoevenson taco sree er ere heat oot eee eee 78
Mesolobus sDunbariand! Cond raleesss-sses sass reese tteectnceseneaseee at teeneter eee 49
Metacoceraswere sec stasdeder as 20
MetriolepisxCooperandiGrantameesese cere tetee ce mettre eeec eee tees te etter 102
Mexicana NGOompositamesscnetetescesctenn case assess cateceseverneereeee totes 96
Mexican-Central American geosynclinal belt ....................cccecceceeveeece eee 8
Mexico....... : 6,8,9,13
Chiapasiveseee eStescbseneste seanscGwewatbaecs shen atswasen eae sce tee see dcereoes 9.16
Coahuila
Tas vDelicias's 4: 22st: i2e 5 seschscdecsesee se stearate caee eee aoa ee 9,69
Gulitofieessceees ty
Sonora ..... na)

El Antimonio .

Yucatan Peninsula 8
Meyerhoff (1970) ... we 10
Miller and Williams (1945) seca PEUS
Miloradovich (1945) ..............c0sce00 72,77,80
Mimaria Cooper and Grant.............. .. 108,109
Minato: (1953) secre ae seen s ess Secteeeeee eee 98
UNS CLIAMCOMPOSIIEM. conascanen: sesra acon t toons aeetete eee ae 96
minusculus, XENOStE GES .......00.00c0ceeeeceeeeeee 4 %...-) 55245255597, 585121
MNINUl G1 COSIICKUL Qu meeccneatanaessens saesedeeceene 8 ...... 5,24,25,37,96,97,98, 125
MUNULUS PANADLYCHIUS) wensesdass-2sesneseoe-ceseeses NOW ee: 5,24,25, 107,108,127
MirélessRormation.sreccsetteccceosscceesastencusst-ctestss ss cessssesnsesvecrour teens 12
MMH (Ministerio de Energia, Direccion de Geologia, Caracas, Venezue-

Day sod5e Seen tata atone sen c duet scene ceensadecav ses suaesenegudes awaewiy ore aeet we 5,39,40
Molinate Ds fesscgecteac cesses ss aazeacacide coca sens eco sens dude dav ate seaeouscceases te eee 5

134 BULLETIN 313

IM liniaem emcee cee sxncserins se Jasisestseceaccesseeperieeinion BaD
MolinassVe scsc.-2:--:
Molina y Vega, L. M. ..
Monos Formation .....
WRB RABIEGTIN. cascancesenece CHCOCad- EBS RO Ae EUD-COOncLCcecocanOsOnacr civosooeecue
IMO AS J2\s ane =cannS co Scq DAL ERDSCAAB DEO OAD CONgECEDCpOnIoNTo TCC cooRoseobosasosncHANcEsTAntCoo 5
WORDS 1 a occecesiasene snOnae EEO EDO ENA cSRO CSUR CA ABOACIC CODE STONCOLe
WSS 5 Sscencsecocsteos UNC oEDARE CU JoeconcRnghenaprancocedonooogs
Moreland (1968)........
mormoni, Terebratula ..
MOOCCONegesnccesers ets sess
MONTH RD I TTOR AIAG Eorecenccacnrnnrcec soEeeon Heaeriononorecsoca-sneasce carn 72
NOE) Eb, TPs scccetconcnacnenccnde tenors cOCnco SOND OgUeICaOCODEneesenoULOSsmadoceoopemsnacacon 5
Mucuchachi depositional basin ..............sseeseeseeeeeeneereceees 31
IN AUT EVENT FECTED aononcenacenboecoocoocno sc acncconuneshre tcosns-cAnase en rep 1172
IMucuchachiHormationtieseccrssescrcancet secrercartrcer te -ceessncesesseaat ereeenstaee 12
IMNGUPAtI SENS cecece-s saves ccess see se sak saccnscceecacenssc teaseteesancs ses ey LOSI
Muir-Wood, H. M. .. -... 16,33-35,74
Mira WOOdi(1 9552) ace, to esocasessvesuce ver se seteeste rock cheese ines oct Beret ere staoe 106
MMW OOdN (1962) Eee etenes. cneosisan sane weiss eustes acvieemel nem -caceemton ences 49,53
Muir-Wood and Cooper (1960) ............c0ecseeee ees 30,39,55,59,62,66,68-70,
72,74,76,77,80,82
Miullereidicocmettecccsccse: ea tanse mneenncennsnctivetiecasecisiateeteeneeaa 16
mulsa, Cleiothyridina seven 04
Murph ype tocns ce sccter aot win ex cecw ees sive seine Sasol set encee iets aaee ad sselqeecenit de stake 6,10
mana CleOthy ridin die’ icon. so: sc2se0 oo. ce sane se caco's Sectant one seamsceeease eee ase 94
aa (Ge), (HAT BIRCH TCT Beoccoessnsb-0ceocebpanecrondoodcencos Ly ceocde 21,94, 125
MANASS POMNLNSIC: ccs -2se0susese-n 0s dca acest assed oa eoaeuen Neeaens snnceleet amass ewes 86
MAKI OSA MELUSLCCIAG (oc -1 Jaisccunecacusseadaeceeeinsecucores en ade sscndecetenene Tee 91
nasuta,
Derbi Gli ox cece cone on oecscen = seotean nc acu nbeces Waste seod sneseue sedentios pea seeceaeeaee 46
SS DIP IPEN ELINA) esses culos ovate cs oetiase vase sve Sexstessscucereeceab uovceeeeen fas ca teieseees 104
Naticopsis
CHINE ODIGIUS AWANLEIS 11. zecsses-hon cue ease ccnencracestes ences secs eseweeetacereees 23
SDivepiece cas occ ncccrvcescacebeannstavvise dege css cave vase ceacewaey uss ssenehaetemtnesaiawcsas mene 30
SPN C lireren cmcraoe= eece reece ole Mensano any eae eden sce eRe as ee 28
NationalliScience Found atOM 5. -<<<cne<--cacnens- o-cencsinsevop vest vest se nasmuaeseenanees 5
neali, Neospirifer .............
INealbRanchvROrmationiinecsdcectaseret-rccscectesrosssee senet cere teceas
WNebenothyriseMinatol cactecdsceesecnsnescnccceresecehessneatare seals nsee
INCochonetesyMUlil=WOOG vsec.vess-scec cere case staes ence scesee sie oaseen oe eaaeee eee
SP seca eey be cess cic acka ctr vphssansk savas Sezasniavetngaiis a bow tstmaevag ants aaveuea aoe eee

Neophricadothyris Likharev
bullata Cooper and Grant
catatona Cooper and Grant
conara Cooper and Grant
cordata Cooper and Grant ....

Crassibeccai Cooper and Grant: 2cc22: cas <scns4re ses dans vomenasweceanerantewes 98,99
cf. N. crassibecca Cooper and Grant ......... Siensess 20,26,27, 98-100, 125
RUA OIUPENSISA(SHUMAK)) erncesccetectencciretsecc tvenee couse erence aeee 99
transversai Coopenand: Grants... .-.<csscestcs 221 sertvacrascsstouenens creates 99
Neospirifer Frederiks ............. 14,17,33,35,100, 101

amphigyus Cooper and Grant... LOL
apothescelus Cooper and Grant so, LOH
PEER PHUDOREFINDANR oy-8 = cnsns toe atnndoeuedetaes Biase sce Toon ca eee ees ee 101

bakeri columbiarus Cooper and Grant .............00ccc0cecseeeeeeeceeceeueeeee 101
CAITEVAIUSANMOTION) feen coseces: vastarousn oven ees eos ceee aes Ee 101
Hormulosusi@oopeniand Grant, “-..ss.cccossssessstes-veecsss venesnoe ako 101
TUE COLTRI SARA fo ancy ce Sayre x oats dons cae sea Sevuxcac CAR e aT 101
iavusen barandiCondras .--rscecccasaareestsae veces sc nor are ateeeeee dear eet 101

mansuetus Cooper and Grant.
neali Cooper and Grant
notialis Cooper and Grant

.. 101
cL
reOL
Migciauss COOpeniand) Granti:.,., <2. -<crcsscstcn ee eee caesar Cae 101
thescelus Cooper and Grant

WIDE AUISIIEIAN iow ocnstesedsaeciscoesiscestec 101
venezuelensis (Gerth) 526,27, 100-102, 126
Wepalitaeysssstesiicsds>s 62
Neuman, R. B. oh sorties oie dasetiedu@enercanaeeeRetress 6
Nevada ........ Aye : Senda dutvaunc stsleifeetee ieee neeeee 66

MeVadensiss (Chay ZB ALAYINY OMI ca-n oxen deen selects ee seenaricess oe sinean teeta eee 74
Newberry (1861) .................

Newell, N. D. [NDN] ..... . 6,16,20,23-25,27-30,34
Newell Ghronicvefials (949) esecsnesescsecmeemad een asa seams 91,94 ,96,99,102
NewellhiGhronitcversal ® (1953) joc. cnet aseanetixancoacsoncnessen=enesereaneenen 10, 13,91
Newell Rigby enialy(1998)) co acn ne cnaannas ane snnesnign moh aie taee etn 47
New MEXiCO\ 20.4 /ses8e cb ielid cn ceecnesstasnssssede loobancacaszactee tana 9
ING GES ceesencccseoce soSeB ro nco ce Pano od (UO Ce ARDEA San cA cobcescoomecncnaarcaesnots oe 23,32
New Zealand .....-2c.:.c.20+<--« 37,102,104
Niviconia Cooperjand) Grant. .....<20.<<2s0c0<ss00-canceasessenesnies Jaeeneeeeae 47
NMB (Naturhistorisches Museum Basel, Basel, Switzerland) 6,39,102,126
North (1920): s95 tec eeceetie snc cdadticnncs eawlacaieazaccesan ue Cae eee ee 102
Norwood and) /Pratteni(1855)) .<.:..<.:.2..-<cas+0s<ros==>acner stanton cites === eee 81
Nothopindax Cooperiand \Grant...<.<..:2-<.2-<<--=-s=erecer tes eee 41

notialis, Neospirifer
nucella, Composita ...
Nuculopsis sp. ......
nuda, Spiriferellina

Nudauris Stehli .........

Oblatus\(GE:) NGL COPSISY sorcrcccner ces arate sees «eetenes niceeenss eile see eeet eee 23
oblongata,
TOX MING ci sdnecscteacvereSuucenadcestaccescucsctcedtetanee sare teh ee eee eee 109
TGXQSIG) Ro aetececduccadec sx tuveesaeece sen sdaseoeteces ¢snpet i tce hee eae 108
occidentalis,
IKUrorginella ccicccssvecscececssaceuceves secede oe seacesevee estan sdedeere teat eee one
Meekella
Productus
Rugatia
occidentalis parvauris, Rugatia .
Odontospirifer UNDA va.cc-wererceee-ncasensi(oeeds utes eecebseee=s ee ee=- eee eens
Oehlert (1888) os eee .s.beccecces-ocescsveccess cacosesqoseseaeededa aonteee eee aaa
COX (1 (UE) arecononeccencanpoosenarsosace snoobscnccaoccocasnwacbScasiasccsccsnncos aed Le
Oklahoma: ..2 cc. 25 acon. cosnectoes sere sedessccnseveseacnereeateseetes en eee eee
Oligothyrina Cooper
alleni Cooper ...
Oligothyraria rier eee crane orem one: sess saececan onan eesmeneeeee
SDoskeen Se
(Oncosarina Cooperand)| Grants <2r.c-.c..2- one ee eoedte= sere eee sear anee ee eee

Onycochilusvsp: Indets cccc.cccsckcrses ceca eset cn semaresen one ieee eee eee 28,
O pik (1934 )).22.. cc. soetecdveses conven soshentece sso ee }
Oppenheim (1931) es ioc. cece cn sesweccneseceqccseneemeness soreece tenant essen a eee
OD SIG; FIUSLECIG) sc 2cn- cancecenc sce sececctne eres sen trieee onde e ete etn ne ee Ree
opuntia, Echinauris
G2Orbigny;(1842)) i. roeceenesces occ casseninetaccucttcce se eanaece en eee tence F
Orthonema
SP iiss cece ni hec Socgsectee nec sed rte cused do cate eees chaeee ecco encore: coat eee
Gye LS (= ine aaneonsis cacnesendbk bacsconnrackcnone uiacaadbancandcstcioitacsscansrocston
?Orthonema’ Sp. indets <2 ccc. cies seceneseeceececcssstesess « ceee cote ee eee 25
new; genustatt- OrthoOnenia ..-c2e-n- coneocscne res sec es onee teense ene setae eee 24 |
new genus allied to Orthonema . . 7S
Orthotichia Hall and Clarke . 40,41
Otsuka Coefficient................ 13,14,16
Q@uachita’geosynclinall belt <....c22,-.c-scoscces-ceceesnccenteesentneee ee eect eee 8
Owenl(1BS7)) \.cccisercccaercedonuececuseerccdoaveecaccareanticicescher Se nieee tests tae 47
Pachy pRoiaisSp sos. ynavescctecxessnsieayacien vesntendeeae akan ghee eee ee 2B)
Pajaud (1968) ... .
Pakistan; s0scsv sui: scovedeeinssoneudscsetecs ssa oetuadseace aces; soothe ee 62
Paleontological Research Institution (Ithaca, NY, U.S.A.) .....cccccceeeeeeeeee 5
Palagostylus Sp > (Get. .c 0s. cnsests ans «-ne=2snuceas saecesl cas ehsae eee eee 23
Palaeozygopleuratsp. inGetin csescsvensnssewee ise te=s sees ate eee ee 23
Pal miarito Pacis cc. 22e 28s vecee eee: one nemene ents Eietner ie een eee nee 12, 13,31
Palmarito Formation
ArnoldicollectionssNowArs 98l=Re yeueunausieeeres seesedseshenes st eneeeee 74,122
Field!No, .PRB-71-VE=12;...-2.02.sccsssss00suipsssoaacavsscnceaecastheee een 16
Field/No: PRH-71-VE-23. «. ..sccscrcusenecuneessessstnespasscesses doe asee eee 48,49
lOCALItV AE tree oatn ese 14-17,19,20,24,35,52,53,66,67,69,73,74,76,77, |
79,80,88,92,95,96,98,99, 101,102, 122-124
locallity,.2,22:3 .eeecsothasenesac tien ee eeeerc ee 14,15,17,20,24,35,50,51, 119

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 135
HO CALL 3 yaWorec.cceceostisevonessenete 14-17,21,22,31,32,35,36,46-49,82,87,88, CostatasaCoopeciandiGranteesese-eeceseccencemeece nse senstemccNesttd recent esee won e)
90,92—96, 103,104, 106,119, 124-126 BVE STINE W DEITY) Mies axe nsessesnanw enue cnervesunesensrewernbevouwesceunmeceetieencettee 76
NOCANIDY TAY cen vecee«ccceeens =x 14-17,22,32,35,36,43,44,46—49,52-55,65,66,70, mekeei: Muir-Wood and) Coopen ...-c..sc1sscicsccreeestivdectsseresecaserneae 74-76
71,73,74,78,82,95,96, 101,102, 118,119,121-125 DENiculiyeratGOope wand Gran tumencncae eset acceceeseseerserssvencecesessise seme 76
HOGA typ Ssccpecvcs sant ance secsciesacsscvescusssecesece 14,15,17,23,31,32,35,76,77,123 SUDCOSL ALA (UKING) Nenececcnercnciceneeete «pick sane ssecacecsrecesyaavecceeecdesstereees 76
locality 6... 14-17,24,25,30,31,35—37,60,61,88,90,121,124—127 subcostata latinamericana Nn. ssp....... Cixi 5,20,23,75-77,78,79,81,123
block A .. 24,25,31,32,40,56—58,60,83 ,84,90,92,97,98, 105,108,118 subcostata subcostata) (KING) oe ccn neces -eoae-cececs sre nsenes duceeweesesceteee eee 76
BIOCKIB ty acschacsteesvedeececece es 24,25,56-58,83,84,87,88,92,97,98, 105,108 transversauCoope sande Granbrsesencre-sensxsachadcuecermeceteeebaar eeeuecterstire 76
DIOCKS Gato ert ccesesiscvareasssctcss 17,24,25,32,40,46,47,56—58,60,61,63,64, IDENICUII fer, TPEMiGULAUNIS) jescuvcccsuenecesciosenescesesecess cee teeeastaracenaeteet ers 76
83,84,87,88,90,92,97,98, 105,108,118 PENANNUlALA WANISOPN Ql tec scant exccurc esd sueestec sere tee cnancant retaceatcenee ates 28
I@YeETISY 7/ Se -soncmancosceocooRBes:oscu0aD 14-17,24,26,35,40,41,48,49,52,53,65,66, PermiansRatiomeeeerennscsecsecsecsrciescsesscowatdescadetscvaceste recs 5,6, 16,19,33-35
73,74,80,95 ,96,98-102,118-120,125,126 Permophricod Othyrismb.aNlOValecsn-scoet veer saeesseaes eeeee sees seecsesceseaneesesacias 98
NaGality: S/o... .ccesecees 14-18, 26,32,35—37,43,44,48 ,49,52-55,66,69-74,78, Perrinilesnhillinw. sac, coc the seer twe on cee Meee eee see ee nen Se ees tla ae Sen 16,23
81,85,86,88,92 ,95,96,98—-102, 118,119, 121-126 PON reac se seca s wavni vies seapiecsesascn tas enesseeeme esse ccuranct'eutocwedcanedetraas 10,13,91
BOCUIRU BLOM icoc nceaee:canestscewevewes veots 14-17,27,28,31,32,35,45,67,68,72,78, Wak ev TiticaGarss<css7.ccccccassesscuansecteeses secure sodtonvarscenawecs nea taenseassees 6,86
85-92,95,96, 100,118, 122,124,125 Retasmiaias Coopeand Granth nusccdcceneeccadiesrwerssecte sender encase ets 83
HOCality All. sc ceesee: 14-17,24,28,32,35,46,48,49,64 ,65,67,69,72—74,78,82, Petrocrania RayMoOnd) ii-ices.s-c22:<ceseoeks. = seeccecestvcceseeruerrsess 14,33,35,39, 40
85,86,88,90—92 95 ,96,109,119,121-125,127 diabloensis)Cooper:and Grants conc. oc~ ceecesecass ieee eh odes casenaneecetesae 40
HOCAIIRV AIS Mrerateedtat ess .rsses 14-17,29,31,32,35,42,43,46,47,54,55,63,64,70, exasperaraicoopemands Grantunereeacscncecese tesceebeecnens csr seceencatar eens 40
72,81,88,90—93 95,96, 106,118,121,122,124,127 sepliferai@ooper andi Granta 22.22.05 cece sneer saeceue (+ aan sssceteeceees comer seeeste 40
BSP aLeN aL ORS ELLES Gren rescence causa s-Gncnecw ancien sso seca onneetees aciacter semee acres 10,11 teretis' Cooper and Granteerc -neesen ee as cas «screeeer esse Niaestaes 24,25,39,40,118
TBER@LAUGLS 1. oasaepscascaddsagbouo onsedo008 coasndd Soe scdecosEOnoccGobdoeobGbonansadcorincasosd 6 FAITE USE pcensencagnocncaegcot Resoaer karte cA joao adhocu -ereecamnnctoctnncccasustes 39
_ pannucia, LD EY DVI A pemeneeee eeeaice iene ieeenaaac sareecen een eaeee ne cmecthc sete sew eenias 46 Phricodothyris) Gorge iencscsseceescaecsncnecescawaccsccee snevaecsveces scessererser ts 17,98
UTTISARAG — oscssobcos0g0eneagasonoesanb0059000 5+ HospaodesooaboDo pao EdduuCaRhoveDsaoge 12,25 CF optAT INC) TOTS aaaeohcannpneponaseicoonnoesena con cancreodcranopendrriccectoacr-coddacdn 99
UAT Mme ete ec ree dace ck <a orer enc sec osedeccecococewernceeeedthrecscsseans=s 16 Pierceyerval (96) iptesenescs csncecccscossncececasscrsrenecneneastienee 11,12,31,33,36
SCUIGEGISR comcoa Bocpootnnocneec eRaOne ect Once COREE RO REREE ERE OSLER E rene eers4 16 ipilula x COMpOSitay secs se erken essa sce cseieietedetascenseccasicasssvatccer home sents 95,96
Bt, 19, SALATGBH — ossoncgsaesnosocceccucooscoadesaocecoccarenooTak eo LoneebcdouncacucaTaag 24 pilula (Cf.), COMPOSItA ........0cc0ee cece eee (cannes 20-22,26,27,29,30,95,96, 125
ArAQUAYi\.ccss..sccsecesses SS eReS CRG OSE Si same we ewe u ool cassie oiae PRN SMSNES RETO DEE oe cc geet e 10 pilularis =| GleiOthyridian wec-eccescen nec ecosessrccsecmaatttectes deere dae erate 94
INCA COMBE AL Annan eet eeceea seas nares see cieneensenianceaneeteesericecte renee 78,79 DIGGLAUS WING OSDINif Cram c-tccetceseeei sateen ce errerenieamen concurs se reer 101
araindicus, Productus (Dictyoclostus) .....c0..coscccvwsesveveeeverseerouseceas 77 fA LAOS, JOSOKOD (U DIY@TOD) \acaer canoceec inecoeopeabncheepconbsoncceconcosdnece 51
RCC ILE UD ONAN gla aie oa csv wccackcn=seuenccwsvanavccntincssdedeurenckecescs sto 109 platy ssi GOllerntataridincsnencnsadenca 3. ceess aa eecmee ner cce antec ese eeeaeteeee eee
Bai) LE LOMLOMESD amenneer tee eetantensterenc tise seein: svetcennisiarse vee teciecs smmeme sens 23,29 IPlatyWorthentasp sa gend: cecesceseccottaten ee aectnc eon ncine seeenne dacace sec rece eee
BETELSD TIE TIN OMR CEU vestie es dacanc ser seca s accra cenaescnecer scar odecenemecrereececat tes 102 Plectelasma Cooper and Grant
parasulcata, Pleurelasma Cooper and Grant
(CADDIE concareoqandeepanoanobbbeageeokodebe saonco-oodo-eoconcasnacceboooceAcooecadoas 96 (Plicatulatstriato-Costalia) COX. ccnsnc sess saacieeee-meeneene=<ee 47
TAR GIRITIVETE — bcocodcécastaconqooeceedasqag2e-cbaaccapsaccaqaacosecoccuaceasbonceanasc 70 Polymorpharia Cooper and Grant .. 67
parva, polytreta, Cooperina.......... co Ou
SACU DET UI ANTM RO Re soo oo s Sasa eos wceccs uv sla secstuscteassiseesstses §7-59,61,121 Pontisia Cooper and Grant , 86,87
LETT TIES « crsicece pe BOAR CCC OO LRU ARIOCED OC HERR OS OROGCR ROCCE RHO OEAGESE 63,65,66 costatasCooperiand (Grants... -- cee nnne tee soem eer oceans 86
PAPAS Ute Me ee sie aes)e chee cos velo snjpmsiasta wanicloue olde vcd ave Halal Sunbleimclestiaeess nice 86 franklinensis Cooper and Grant 86
parvispinosa, Kutorginella 73 kingi Cooper and Grant mos th)
parvus, Dyoros (Lissosia) S1 longicosta (Stehli) ..............065 coe tH)
BINS ABIDOISESEDICS foe ope cise sls cveu'vicns su cavseeea sen cesceunis setteceounosveaeessRasneseeee 10 magnicostata Cooper and Grant 86
MRISCRCOSIAIA eSPIA PERCU <<<. <cc-asnccse ct caeneesenusteaseccudvdvettoeeeeestectres 104 Maras) (Stehli)kessescs--eeseese see 86
|. Paucispinifera Muitr-Wood and Cooper 14,17,67,69 parva Cooper and Grant ... 86
auriculata Muir-Wood and Cooper 69,70 robustal Cooperands Grantapen-cersascsceessencese cocee sen seeeecaeneaceentaeeece 86
costellata Cooper and Grant stehlii Cooper and Grant ...... 27,29,84,85,86,87,124
indentata (Girty) ............066 SAABE SHAT (Covey oXair BLYG| (Gi ALN a7 cece acnceoopoanoacoennotbeoncososncoocosceeose 85,87
intermedia Cooper and Grant. 70 stehlii tumidosa Cooper and Grant ..............ccceceeeceeeeeeeeeeeeesneees 86,87
latidorsata (Girty) .............66 70 ef. P. stehlii tumidosa Cooper and Grant . 21,86,87, 124
magnispina Cooper and Grant 70 truncata Cooper and Grant... SRE C CORE AOC ORE UPD RecRopreincecrcncacgnco 86
parasulcata Cooper and Grant . 70 ventricola Cooper and Grant ..... 80
quadrata Cooper and Grant 70 wolfcampensis Cooper and Grant . pom, tee)
rara Cooper and Grant.......... 70 SO Anceacanceonoconer eco sos acer crecnen 86
rectangulata Cooper and Grant . 70 portlockianus, Spinifrons . se 81
spinosa Cooper and Grant .... con tAd) prionota, Meekella .......-....e00e000 ees
sulcata Cooper and Grant .. 67-70 problematicum wordense, Dielasma . .-- 108
suspecta Cooper and Grant.... 70 productelloides, Echinauris ........... 63,65,66
transversa Cooper and Grant . 70 Productus Sowerby 17
tumida Cooper and Grant fos, 1D costatus Marcou 78
Paucispinifera? ...........02.+ a) 33535569 COSLALUSWS OW ELDY) noe vosiexcoiam von eslg ote acioh cnompiene alts euniuese ses celecmeites daw eve secs 78
cf. P. sulcata Cooper and Grant 27,69,70, 122 OG cidentalisMNEwWDemy ners: ccc--cecs ore sens soe sce eeaeee scenes deatanee eee aaeeeee 78,79
PGI QARLCXGVING) . occ sccce cnc oeesseseeese Ree l09: Productus (Dictyoclostus)
BERMOV AN (LOGS) IM cos uniccccwseevcuheedorcoesastinessansereelesees . 98 WRERIQIOVIGUS) MOK CG i Fe caxciance ade weiesev ces sommes sneat ene sie ce ome ee erate 78
Pawnee Formation, Laberdie Limestone Member. 57 [DAN AiINdiCUSHMICK COM crear oaeaces desteeenenas azeceet onceoe eae nee ee ee acee eee 77
Beery al lanewacerh se actin con se Genctisnduecceeeseoasess 25 SEOUL LE CCHET TS) idee dSeonacscappesedoonc: ce Jon eorise ost mecdaqos sadder aevoocrocade: 91
Bloveri Newell and) BOY). ..i.c23)ccseicsesxcsscecccctouvesatkerss 24 PLOSP ELA; \ COMPOSI Gyn. noe sane tenesaceare notes Retenece eee edees cde se dames 96
Ef elovert Newelliand| Boyd) ...........0-20....ceneseeceeeseses 25,29 PS CUCOCAIMICY.ALUS™)S PILI CMCL imate en ecsieeenslesen machete seem en een eee eke 101
BEM Chi) EOD AOD AY IIATU IT cece onuccsactasstudats ce wat tosteeeak est eeeaee eee 28 PseudodielasmavBrilligncstsccucecusascaceccasceuecuan ane seaeencsncdtes cases seeeees 104,106
Peniculauris Muir-Wood and Cooper ............ 14,17,33,35, 74,75, 77,80,82 brillieEoopenandy Gran tug 2 cadences een ae neses olen => sain eiss dae Ae eo 105
BRESUBNECISC Ceca ceas act tc wate ae tice soc ee ccteneocganeeailneeteau cess snore diese 76 IPS CUAOMONOLISISD a een teette ha ee ae ca tscn cannlonainen se stneeseetiesecaeea estates 28-30

136 BULLETIN 313

Pseudopermophorus sp.
TRU TEES RTT “seca Resee eee 80 S20 SOUR ECO REDE DOICOLO COO O-C OAc OOK I aIIS 91
Pugnoides
LER LAT SE GLY tee nana acos Scare enn ssate ae nee cane cee tas eaaksien sense sie sc asieletenfeteaar
AIBPAOS USIITS Seca ss8 specs se5e 02ELC CHOROID ROS DU CREDE RESoe cOmenpaceRCocoD DESC
REXANUS RIN Dees mene nes se races ccscthasacs~ acceeecare-sunudersaddduessucenancenracnare=
REZ VBS SIN UIENRG Soansnsbessoes scape sane ee anos subchesancencanosoneceaoonesos
PPUMCLOSDIFIEYRIN OL Nocera acane- ere sex on sae stene contre te ee nem e se ase
pyriformis, Composita

quadrangulatus, Dyoros (TetragOnetes) ......--+.-00cceee reese eet eecn een eeen ees 51
IQUOAI ALA LAUCISDINISENG seccwe-mejetanassavnder jeer Secresiiensen= ems eseethrmr doa 70
quadratus,

SVR LRETRS sche sees HE scace cee eceet oosencbonncconderconnoneneene a aoe seeeee ase ese 80,81

ZOTOSIBEOS 225500 PASCAL O CRO RET DOOLDIEDEOD UII ODEO MELNOT TEAS MONOCSBODO SII SAIOSIES 56
(GIG FTIE NE TTIES SiG 7 Nes gp seearacecn ster rico coeocSncc ase auiaaec So one oasee CCDS IES 17,49
(QUESEE sesecetesecneodecdocc conc O-conoo SneRgoe aS acoSSACEnceCoHecoNSEMneDOgoTeoHOSUE ELC 23,32
RORIAQVECIUSE SOD litesteereae-eaceanacecacastscuncsceseeteserenereatercedanncces 14,17,59
IROIMAVE CLUS 2 wa csveqscakenscecccssucavcesdessscucdsaceencscecses chescedesseceessrsceeste 33,35
Ramsbattorn (L952) bac cpnccnanect etre o-cest mands fee eoe hs vankak vetiex cs One Peeceemates 52553
rara,

Gleiothyridimaveercncss tec oce cosce 7. sedeps ose tecececnnarssnetounewencteeesreseoncts eclece 94

Paucispinifera pone: fA)
Raymond (1911)..............--. ~sw 89
rectangulata, Paucispinifera .. 70
Rectintarcinata Gl eClornyridinGy orcs. secercecssenese cree seen sececter ete seae seco 94
ANS! TEOTMTELEOS!? — ecobeoses soeccascoobocecosctesocesnoconocoaaeococaoccbbecosooorenubos 11
Red (944) corer oi: vv om ssincacsctinsscisnes cian cules cutemeeanaee ess toeaceamees eeeendey 62,102
TPP UNATIS NET DVE hie cen cece rac css nna oats eeenieeeae sence ss aerneea ee eee nen oee rae east 41
Retaria umbonata Muir-Wood and Cooper 72
Reticulariina Frederiks. ............- 102
Reticulatia Muir-Wood and Cooper . 77,80
RELISHIF AGS Pale Cammntiees ce nnc vaenck ween s on chueoancasemennoneoenes reese eokecmeenes 28
RREEZUUSH (L781) Sow -ceeenan soneceniccee=- sous ocoslon corer mee tetas encanta emcce reece tees 39
PEVESSUS EC HONEIUICLES ae ee cninseaencnee sean stec se <eceeecknae ener en eee eae ee see 53,55
Rhanmnaride Muir-W ood and! \COOpen .s......5-.0<rs~secseres«sseve<fe-etetscceneeres 59
Rhamnariidae cf. Ramavectus Sp. ......-...00.c0ce0eee senses dex
Re ipid Ome lasOenlerG cccccs-eo cee awconescuees erate en Tees seat Te
IRROMPOPOFA osu: seus ssencvesetstensi
Rhynchonellacea, family uncertain
HCAMMCHGD OF Caweee acs seer te cen ereeeee
RIC MUMOLE MN (NS S2)ieweeasaseten os cocecuncentueceresdar doaeounneeueunene re ie teee eee cneeees
RAGE o EGR et ccc ctee nc <cowans-ceswecess cauvncnuee tenes wees
RIV AS WAC eaten eece ton cn ct ranstus sodeasuce Suse. soils Satan ees Seed Seen ae Es 5
Road Canyon Formation ...... 14—16,31,33,35,37,43,44,46,48 ,53,63,64,66-71,

73,74,77,86,87,90,93—96,99, 101,108,109

Roadian stage............... ee Ub?
Roberts andilinving (195i)! -.<ce.osscsencsoccenca esc cartexevecencn Maeve wncs cneccanccues %)
robusta,

IRULOV- SINE) tres coc. ces ease ewe naa tsdes vasecie ces so0eete Dade Rent w eo eo 73

POMASIAL canancrce eters scvesesseaecusnasaclecdden det oscucw ue dnceeeee rece eoece eae RCE 86
TODUSIUS MDVOLOSS DY OF OS) iavacacat scacvuvesde sca anuakcoceesteaccesneseeenarereeeeseen 51
ROMG OM Aces csscvedulen dove oot 8s <ncuce sues cponscs sussacnsceacesdsaus asus cteec oot a eeteee eee 5
ROSSI(1967) oecesssscenacasesvocvesusvsreqavencerocasesset ocavesecnssceesoateaenertasedetes 10
Roundyella sp. . ep ARDS
ROWEMNMIGS) esas recess sve <scecsszcciessnencessncaciepsvadesdeeaters cum caeoee sete 39,40
FOV SIU RUA ERY PIS tase cnc ctiy dapeis en vale sviwaeiiewss vats seacseccessnnen Gh eee See 93
Rugatia Muir-Wood and Cooper ...................000e0005 14,17,33,35,77, 78-80

andersoniisteniirandy Grant scscczs-ccece > <5 dencces scacecuseeetee stereos 77-719

convexa' Cooper and) Grant 2cie.cs0se cco iecsseecsccatect Tete eee eee 78,79

incurvata (King) .......

intermedia Nn. Sp. .........-.

MmakeenCooperand Grant: ..ccs.s-.s2-ndevecerccnsvncceasarteer ce eee 78,79

occidentalis (Newberry) .............00.0+ 6 ...... 20,26,76,77, 78-80, 81,123
parvauns Gooperand Grant) 2... ccresccucse-cacvesnere a tecteeer tea eee 79

DOraticas (MCKGE)\..2.5-svscsccvansencscnceacuxs Ceesee tne Ta RR
Rugosochonetes Sokolskaya ..
rupinata, Hustedia

12,31

Sabaneta facies .... Per
12,19,23,27,31

Sabaneta Formation .

Sabanetal Groups: 22 ceseze ae oe cw dele none dene eae aren acuie eee ae ee 1
Sabaneta\Seiies ead tet A nal d eS. 1
Salt Range 2c x2s 2550. Bie dite asc ctce cadens nccenccdeavcveceovyeshpesehesteass eee 1
SaMiataNTUst edi dizew-2) crsevede os v0de oxo dort ods Sev Sedov vdevs eee Code aenE 91 1

Sampling Efficiency Index ................0++e00+» 5,8,19,35-37

Sa MELE Be ral (970) woe mine nee testes tees ase aoe loa e eee 13,34, 72
Sanguinolites sp. .... 28-30
SantavRosalGrovprrestscsasssicedesatenanescearsneencss ewan \
Macal Series ¥i20. 02: e2-c0s set ecse sahee eens deeveccus
Sapper (1937) sod ceewsshs eee oi eae etean saves evce snc ee evade vee teeee es eee pe eee
Sarganostega Cooper and! Grant 22..020.00..cs.venesesseeeeeueernere an ceeeeeeeee
Sarytchevaii(197/1)) cs hese eee Ra cawesscccecnepeeh dost ce eee eee ene 7
Scenesia Cooper and Grant) [Pees cao. seeeeree een eee nese nessa 102,
‘Schaub (1944) iss 2 cde. Sse dvSod sevess coozeescctbes.asccee teehee ee 1g
Schizodus canalis Branson sf 6,20,27
‘Schizophoria*Kinig. .co.se2..eh-doth arse dt eeeh «coe v0 sa vena aoceeae Coe eee 40
Schlotheimi(1816)-%..22. Asie. icdi ater vs ceac see Oe ee 102,104
Schucherti (1913)! sss. REE ek Ricerca en 104
Schuchert (1935) 2.2202. p..220cccestzscdctseasseoseaautevee--2 pate ee 10
Schuchert:and Cooper (1932)... .<.-s:s<0<00----sveanxendav=<20es ses 40°
Schuchert and LeVene (1929).. 40.
Schiimann (1969) .... 22,30
Schwagerina setum . P|
Scotese: ef al. (1979). <..<2-c2s2 cen: cadvecsaneoesnanesnsanvseecqse see eee eae ee eee 33
Seruttons (G21: (GMS) eeec.s 22: sescssassacceeceotsostsescee eee 6,20,21,25: 29
SCUIPHILIS, JAUSCEAIA: (coscn--+snenconensavusanansosesna ens n<srh reas estsnee ena a
Sellardsi;, Parafusulin ..ccscsssseses.<0s.ceeceesseenenassssve¢se-2ee eee 16
Sellardsi (CE); (Parajfusulina ....-2--.deacenseseecuscdeces- esses eee eee eee 24
Sellier deiGivmeux (L951)! cicccecceseczccceceseeesecesaeeecs tesa eee eee eee 12,
Seminula argentea .........

septata, Phricodothyris
septifera, Petrocrania ...

SLUM, SCRWAQETING.....222.cc0cee0.scscacesoescecavecascuuaccussedeusecdees sete
Shagam, .RuiG. ...:...csceeecce cos coneseadacesseos ceed evceuescesaseesseet ee eee
Shagami(1968)! <..2<2.. s0c2cc.cecceee saeco dewssse cosvane soinssaby ce see eee Ree
Shagami(1972), s.232s02.2.:csscscess scene savacecvsscevascssvdazesateee nee
Shagam and Hargraves (1970) 12
Shaw (1964) . a8
Sheehan (1978) ......... . &
Shell. and ‘Creole: (1964). ...c.:ce:ccc.scee-+eerenensceaneedeee eee 12
Shumard) (1858)... /0..ccse020c0<c0ss2-00-cececssabecedenvuesacs <5 -sse oer 9
Shumiard (1859). <:3:<:s.:..cc00<es0000ces0000cqe0dseeosanp scekoee ante eee eee 9,99
Shumard|(1860)) 5... ..s.20+:sseseecs--sv eee 85
SiGily_ fst. aol ent c ee e 108
Sleveri (1962), .sissie-i.scccgecs ssusvscecivstzeeszecesseet ed eee ig
SQM KG won. se2ecceeee ence cus geese cc recenacee «ceaceaiveneseveees tesnsec eee ean
skenoides, Meekella . 2 21,22,26,27,29,47—-49, 119
Skidaway Institute of Oceanography (Soramnain, GA, U.S:A))) ..s2:eeenis
Skinner Ranch) BOrmation).cs-sseee-scseeecoes saves ce veeceneresteneseea 14,49,74,77 83
Smith, Ao'Gi [AGS] ce. coccc- so: sae cnazcntcncacvssteatavss detaas suse eee 6,29,30
Sohn; Ti! G.(IGSY <.:cssc.cesstistteesiaea ee 6,21,25
SORT (1956) ooo o ooo sane eeennsecensstneceenene srencsvcasssenq as deeee eee
Sokolskaya (1950) .

Sokolskaya (1960) ......

“Soleniscus’’ sp. indet. ......

solidus, Dyoros (Tetrag@neteS)) .....<-s0.2-sc=:-+cdeea+0---eescesseeeereeessaeene
SOME LOX AYAMON aa niace rive aeiesieoaalece-cesieuesuniceeariwederh *enteh ated aaa
Sosio/ Formation « ......20:<css.cseseveseeeseeneessnasexcssensh eo- sate eee eee en
Sowerby: (1816)! scsi 5. sccecscsec ce wewe sents sone bes sncawesen cee os cceece se ee ee
Sowerby (1823) .

Sowerby (1827) .......

sparsa, Holotricharina ... ce
Spatulata; Collemataria Jcccvecz-sscsnuseeeeceeese-4eeeennceeen se seee ae
SPiCala, UStCAiIA) <n. ca2<n0 noes casoc team cansencse ees tnn dunes cuneseake< yaaa
Spinarella Cooper’and| Grant © «...<...0cc0s-c-2<<-00«ssanesue-cena=-oueeteaeseeee

NDIA FONSI SCCM ecnendee eer anamed at foxes es staeunseedeateeee

delicatula Cooper and Grant
BrandicOSta 1. SP. .cecccsescerseecseees Tas 5,27,30,76,78,79,80,81, 82.10

PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 137

pene (Coxe ANC GEING ceetosasecnoncesconoonsaccenonsone sosaocScooncecnonAAIAD 81
portlockianusi (Norwood! and) Pratten)) <.0...-20cc.0senececper-«-ceer ses eeceseees 81
FE EGIIA TIO SIG eect eecacee ences nonce ncacaesbeaee none a nse oe saa see Sooeeeg-oriicn 80,81
SS Peete eae ce eee eee toca tee eat eieaaiclaniclsin elses ceva nce ee melee mela suieueie vis'etes 80
BUPIEITL I TOMES Per eae ease cpeecce <n avieiioas-cieiueh Heveas ee cklecceuctwens Nome deeeeesceecsonteecses 22
Cher SERSTAMAIC OST SPs vas sunt ees ire slay eoren'e UP sonnen 21,22,29,81,82, 124
RPI MOSCME AUCISP IIL CLM mnnccecw sees risneseee ences snceneeeineeecoercceesecace stare 70
spinosum (aff.), Lophophyllidium .........c1ecceeenseneenseeneene Ano) PLA
ROHR SSONMTCIION? - Ceaceeacenscbaseceocde sca coc cu cee CEE aA ORROnGoeEEEe en 10,94
ambiguus Sowerby wees 94
cameratus venezuelensis Gerth . . 100
deroysii Leveille 293
fasciger Keyserling ... . 100
venezuelensis Weisbord . 100
PITIfEV Ella. .....cxeecc0sncoee 36
PDS EUAOGAIIEN LUSH (GIKLY) lesceeeoeeaice mamcebiccneeeetttetstst ees coe OI
Spiriferellina Frederiks 14,22,33,35, 102,103
AIDES TISH(WYDILE) eirccnenseconcssceunc smctec sore oer ans cceeeseceens = e02
cristata (Schlotheim) . 104
PSHE GACEN aoe nee sien eee rich 103,104
ef. S. hilli (Girty) . . 21,103,104, 125
nasuta Cooper and Grant ApoE tonSatoass-eococaanccs 104
Mudcs CGOPC KANG GAME: now -o.eecen-ox conececcensere eset sorte dace eterna cto eeeee 104
pnuciscostata Cooper and Grant: cs.cs ccc ceecwsedeeee deus vosexnceronvecoteeeose 104
MICOSMeCOOpe wand) Grant: occc..ccesenewanecewecceweecuncawenedwececvecasecnsededes 104
ieegaritay (Choyoyayere Gas) (GHEE pensaciocsucaonogdesaconaccaospsadapsaauisoosenoDAaOOGeHCHe 104
BUPA EE RIAN SILEY Daren sicicowa ue cnc enc tien the ecec seats ec at Os et eaves Autos 103
MPRA ERICH A GRTCUCTIKS: 0.25. ocaz exc see: coeceusscucszcussniesevedsedteeccemecers 100,102
BP COT DIL eReme ee ee Cee Ne ec Vane Saceencroeeaecesieeel sxvsusitesseveetadmenediod 25
spondyliformis,

OOP CVI Cee rccn dorscca senses ve wemasjicesps scvescOeeessevet ictce cudnt itievevvacuteeeee sees 58
EFI E ON URL MMe cen ce eh es Soe ak Coe Sn Ta ve a sucee es beke reece tres obtener aad ene eee eae 57
BTOSAKCOOPET/ANGLGTAant, coecnxcze scot savsco snes osuindovvessedees see teacutawedeene 59
Squamaria Muir-Wood and Cooper ...........2..0s.c.scesseeeeeenessee 17,75,77,80
PS TATLT ATE \ CERISE) LETIO WM Gre ssogesscocearoaeann obec seas saeeeepreceeacoaoendeee pons 98
BUSHEY COME NAO oN ache nosey osest acess evebuse osstoe sashes cate tuaseteeiecasstcaaeeness 98
RUA AIMPERSISHBAUD eee: ccna: veces: cxasxohosuaesws Cucsdcviveseceaebisdaederwacenets 99
EC IIIT CONDOS it. 5 <nae s ducct enn stWans sess cece <r tee eens Seee de ne hee eee ES 96
REMI AG USLOO! Accra ctnietvercavecracscsy «toseneseuscseonhedheemeeentes erent tetas 91
BEIM LOMIGL GANS G CMY feccsiesiosc cee seas .sccceesiweccssesessieaeees 5,14,33,35,49,51,52
esoterica N. Sp. ........- 253,40 c-=2-« 55 20,22.26;27,50. 91-52) 55 9 dT
MANN ES Chae cence utara d doc auscns cosesenbsecccecadsscnssencdwaeeoute 5,6,9,10, 16,34
BPTI (954) Nees as .icecoevceccdsssacecsssissecaeaeess 9,41,47,49,51,52,59,62,70,73,74,
| 77,80,81,86,88,92,97, 102
BAEC DIN 95S) Rete ccs seecctien vent wstisutcnccvessese usseccescecdeme neater sace cee todeate 62
BaRC IIE S51) eneeoeeeeteceoss ccavssscvssacsvesesevevencasvevcc,cassc dete coeeetoeotttenees 6
MMM ATLI (LOG ha) eatrctaat seers cts o Societe os vdavssiicccadesesdacssnaaet Bae eest eae rareee 104,105
Sts IAUIE (CLOG) Pere eeceacien sone sien tecscesscetss sec aciuwsanecucudecesecens cc Coseees 104,107
RAPHE 9G) ence cette nscecesensstrciacsectine ssvd couse secuvdcesecusvduersinvstecarsteoees 104
BME IGS) ape ts tose ce not Sis oes Pec bases vce ve sn cosics sareedenae cust eee ots 104,106
SLT IGRI)" Si easesncceaeeneeeerceceacbar cascade chs reco ee Eee eee SEE SS)
Mere LE USM a terisceseescecsicccs ees. deacssscctvousvcocvesec-woiesicadeeessdofsasieeatess 6,33
| isla (ICE) ASdse Ras Res apeeeeceeo Ac aeReSeee Rac peeaee eee nin ta nee 33
| Stehli and Grant (1970) ......... 9,13,34,47-49, 62,63 ,65,66,74—-79 86,96, 106
Meme ikanicde Gran GOT) iy cae cacse ts: deca nyseeess scene Nee eee Ont oe oe 33,35-37
Bepebuteer nn AWiellsi(L QM) sinczsccsee eves vceese teas cs oe ssaeeteee eee me is eee 15S
BTBE IAIN (OOD) sete cecee te cece -sacag cvesnexsscicenscccesivessoobums etohereeee 6,33
BRE ePONILISIAkeer cs ccrcesiesocccsesetescasonseensies 5 eas 27,29,84,85,86,87,124
MEME ILTIESCOR II WPROMLS Ion cacxcuctcosiuvesieesinsscasaissceiere ober nee eee oe 85,87
MIBIOILAOSCONEONTUSI Tuges cscs cavvesnsntes toe at teh eh 86,87
Bieniit turmidosa (Cf-), POntisia .....02.c00sscsascsesse0s0see Ms. scent DL, 60,8741 24
RE e roc iii aa Grantaen serfs -cen oy ee De OME Leake Ti
| BELO ZOS Lela GRAN tree caret ates sere asters Accesses aeeeeceoen scans oape ca SMe 70
59
78

Straparollus (Euomphalus)
Eten Sen (2). yKatbabensisibes ChroniGienecersassecresseesseeter eee aaceee 27-29
TD) TOTES eatoate anabascbcne cco HBAS ea Sheer e Rad Scene RPE RERE Ameer RoRcrn oneal 20,22,24
MBE GH OM CT CSSD iplsvsedacous veees saves 2 vase sta Sods sieoe sous vecwae lé tees soeee Se 29
RERULO-COSLALA’ PILCALUI A) mianentcnescerecessascecae sts sc snaehee daceseeonesecwe sasaetes 47

SIFILOSUS MD VOLOS) (ELA ZONELES) weascseasacecccnacsetseedivesureenesustonentetene ee Sl
PUSEFODEUS, USD AMGCD 2 5. cencve sevessnanteh satis anh eae waka syesusanoueuerstetee ete 22
SirOng Mle} GOMPOSILA iz ienczs23 cavavs ea dees setts SesReNTO dese home TO 96
StrophalostellageikhanreViscecsensssccscc seswosecsses seis daedesaaes-seesteteee eee 55
SUDCOST Alay Peni GUlaUriSyccs..c..ssctncsasccsse aowsessceasisadas coaea sia ceeeteettestoee 76
subcostata latinamericana, Peniculauris ...........006 Gees 2 032357577,
78,79,81,123

iSUDCOSfatarSUDCOSIAlG,.PENiCUIAUPiS).ce-s-22ce2scc2deaeateuseeaeeesereene nse seeee 76
SUDGOSTALUS; AUIOSIC DES) czccicces scvdesatn sae odecacabetudadecss sceeeeeecaes sbeeeene 74,76
subcuneata, Cooperina . BeRCEC ORS P I)
subhorrida, Echinauris . ie 63,65,66
SU DINLEnFUpLAy IMANlOCEVAS) eecscccesersseesesscshereeuaeeetarcessedestensecces 16,27,28
sublaevis,

ANGMONAGHIA a-wsscnce.cacdesonsuaestssasenasceeneneasse Sy Scos0d 27,67,68,69,70,122

Marginifera............. go OH
sublaevis (cf.), Anemonaria 20,29,68,69, 122
SUDILALUS yD Y OLS) (DYOFOS) Wicesssesconesccsccactiseceioneoesneeesesecserteeeee teatte SI
subquadrata,

EGRINGUIISparcces eer sesesene areas , 63,65,66

Kutorginella ... 2B
subquadratus, Dyoros (Tetragonetes) . 51
SU Diilita) | GOMPOSILG wo0cc0scneeseeaneeet==s vet 96,
subtilita peruviana, Composita .. con 8)
sulcata, Paucispinifera............ .... 67-70
sulcata (cf.), Paucispinifera’ 27,69,70, 122
Sulcataria Cooper and Grant ... 49
sullivanensis, Kutorginella ........202..00000-s000+ 273
SUSPECIA EL QUCISPINIFENAner-cne cece neeaereeeecetces aco, AY)
Sutton (1946)... sere sco Sze sesuecieandseces feoecette tees ou suc daw dusses oan davevesareoeas 11,12
Switzerlan@) Basel Wnec.ccosgasce ews ease d-ceedscaesdesenevencuuentecs es peweaceearone 10
Taosia

SP INGO tise ve nec cseveeeocenncavencstaceecwoneeen. oes eaceee mueneee ae crest cmecnimederet tee 24
PRAGSIA=Sp winders 2s ssicsashaeseet ines sangsoo eae tee zeatidasecc scence enema er enee 20
NEW PEnuShafie MASA .cscscpccccocecssssde ces seesaetescceeceseccerssnsessente 23,25,29
TaylorzRanch Fonmationherc-c--2e--csscecscores-scescesctessscecececeocesneecsescceee 14
LENUIS$) DY OF OSH (DY OFOS) estaes tance et eeere ree serie ten ent ee es cease tneeeetesete 51
WerebratulaurormonmMancolscesacasteassdteetttteemtecentsasceen tee ateencer nes 88
Merebratulites:cristatus:SChiotheimres-csesseeseesesceressaeseeseecenceace ee eetees 102
LEreliS; PEMOCI ANIA) fececnerdenesss-neceesnescnsecececsesten=

Termier and Termier (1957)
Termier and Termier (1970)

Mermier,, ermier,;and|Pajaud|((1966)essencessceace-teeateeeesseee eee eee eee eee ROO.
LEXANUS PU QNOIAES: be so doce «Pas oaoes eas eae a eee ee 85
Nexarina Cooper and Grant osecesscscensn see ene eden acne reese 14,708,109
elongata, Cooperand! (Grant cc --<.< scarce =ecesaecssecue snes sectecoeescaner <oesteee 109
oblongatai(Cooperiand) Grant) ier as.ser reese sce te ease are nee eee eee 109
parallela’ Cooperand| Grant) |<. sse.caesvcasacesacccmscnantsns nnaeetaehcnesraeeete 109
paucula:Cooperiand) Grant) iscc22s2.-ds-ccanecceeecesenessscoctesssenvesceeeeettse= 109
solitaxCooperiand | Grant s72ceccssat os cecessensseere tsacctess oo oss eee eee 109
Wordensis\ (KANG) sececsosessesseeseretcee oes ees eeee Oot teats area naense eee 108,109
TOXQKiNQD ci sdsus sev deena secseeneteeeaieees ta ced sadacee sed etn cae eee ee RAE BONO)
Chae worden'sisy (King)) tecenetsacesesesnsseoeeneeeenes 10).22> 29,108,109, 127
Texasia oblongata Cooper and Grant 222.22 scccevecencs- soe ccssaeeneeoonee eae 108
texta; "Der byia: osisccciecsenedaaddoccvotseucsstsdooes tee ro eeen tone stent ene eee 44
JRE AT oe mosonemenepaaonr somone moa’ nncboscbonpencr nour pocopanoccnAce 25,55—57,62,84,97
KeOIMUG ssi geitewartinss <wageaeeacenbeeee as acemevsevacceas dantavdgecsews acer tsarveeeteete te 57
Uhamnosia Cooper and: Grantingececenssre saeco eese seeeaace saddens caveenseer ete 72
ha yeri(1GT9) yscz cess saccesae cesecaveas necaczadavessesQeeaetowettenaceeo eee 18-20,31
Thecidellina 57
Dhedusia\Cooperiand: Grant waz ccaccwnandoouen essa eteneedacd- Seas se senor 88
thesGelus iN€OSpiriferr cissccssssecdaaesesnsedadoscesadeestsace asec ses ae eeee 100,101
MhOmMAasi (19311) a sicoree codes sesvsgesees nese eo rss seesaesss wow sada ene does ae neers 41
‘Hhompson:and)Milleri(1949)) Pave. ansvecsevcs-eoessssaseaeena stander reeset 9512
Thomsoni(t926) 23.scieccus cored ech sennescdeger steve eanececesvadeasecee ten seeeen eset 106,108
TUM AN OLY DAPASD ts oc wncsin ete cen saece as desseeeate saosin setecee see eee vas Ceaeee ses 20
JOT) PereBcote chore aceereechoSCO nce EAE aH ceRCACRE EERE CECEP Eigen moresnie nro sec teec coc 62
Titanoceras . 20

RAE ¢ FACUET ETT ppecsencscconcéronnonscenctesosso sabe. -HoSuescaoa canada aandb-as000 ace 91

Over ARE IT Es

Text-figure 4. — Brachiopod occurrences and taphonomic indices in eleven col lecting
localities within the Palmarito Formation. Circles depict the relative proportions of
ventral (white), dorsal (stippled) and articulated (black) valves. The minimum number of
individuals represented by these valves, given in the lower right-hand corner of each
diagram, is equal to the larger of the dorsal or ventral valve count, added to the articulated
valve count.

PREPARATION OF MANUSCRIPTS

Bulletins of American Paleontology currently comprises two or more sep-
arate monographs in two volumes each year. This series is a publication outlet for
significant longer paleontological monographs for which high quality photographic
illustrations and the large quarto format are a requisite.

Manuscripts submitted for publication in this monograph series must
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of text-figures and (or) tables, and a short, informative abstract that includes
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page text-figures should be drafted for reproduction as single column (82 mm;
314") or full page (178 mm; 7”) width, but arrangements can be made to publish
text-figures that must be larger. Any lettering in illustrations should follow the
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the text, and the approximate position of the text-figure in the text should be
indicated. Explanations of plates follow the Bibliography.

Authors are requested to enclose $10 with each manuscript submitted, to
cover costs of postage during the review process.

Collinson, J.
1962. Size of lettering for text-figures. Journal of Paleontology, vol. 36,
p. 1402.

Gilbert Dennison Harris
(1864 - 1952)

Founder of the Bulletins of American Paleontology (1895)

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