ii
ral Si ies
eT bs if
wy .
oar aly
é i) u y mae
bi a
act
“
oe
HARVARD UNIVERSITY € Library of the
Museum of
Comparative Zoology
Gilbert Dennison Harris (1864 - 1952)
Founder of the Bulletins of American Paleontology (1895)
@
Anencar
Begun in 1895
ulletins of
OLUME 106, NUMBER 345 JUNE 3, 1994
Silurian Radiolarian Zonation for the Caballos Novaculite,
Marathon Uplift, West Texas
by
Paula J. Noble
Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York, 14850 U.S.A.
PALEONTOLOGICAL RESEARCH INSTITUTION
Officers PRESIDENTS. «4502 sore Eee Se eee ee ee J. THOMAS DuTRO, JR. MIGCESPRESIDENTT. 3 eto sens) is are ee ya Ed en eanee JOHN C. STEINMETZ SEGRETAR Via: fortd sacl rene se ets eee ea ee ees HENRY W. THEISEN SREASURER GE oor See Orme ee Oo ESOC es eee. ANNIKA FARRELL TO TRECTORS seh cei es eee ee ee ee te ee WARREN D. ALLMON Trustees R. TUCKER ABBOTT (to 6/30/96) SAMUEL T. PEES (to 6/30/95) Bruce M. BELL (to 6/30/96) RICHARD E. PETIT (to 6/30/96) CARLTON E. BRETT (to 6/30/95) GARY ROSENBERG (to 6/30/96) ANN F. Bubb (to 6/30/94) JAMES E. SORAUF (to 6/30/94) WILLIAM L. CREPET (to 6/30/94) JOHN STEINMETZ (to 6/30/94) J. THOMAS DuTRO. JR. (to 6/30/96) SUSAN B. STEPHENS (to 6/30/96) ANNIKA FARRELL (to 6/30/95) HENRY W. THEISEN (to 6/30/95) ROBERT M. LINSLEY (to 6/30/95) RAYMOND VAN HoutTteE (to 6/30/94)
PETER MCLAUGHLIN (to 6/30/95)
BULLETINS OF AMERICAN PALEONTOLOGY
and
PALAEONTOGRAPHICA AMERICANA
WARREN. DY AUEMONE «.).o/ Ba nl Oa Sim Cent OE ee ee eran EDITOR
Reviewers for this issue JON C. AITCHISON CHARLES D. BLOME
A list of titles in both series, and available numbers and volumes may be had on request. Volumes 1—23 of Bulletins of American Paleontology have been reprinted by Kraus Reprint Corporation, Route 100, Millwood, New York 10546 USA. Volume | of Palaeontographica Americana has been reprinted by Johnson Reprint Corporation, 111 Fifth Ave., New York, NY 10003 USA.
Subscriptions to Bulletins of American Paleontology may be started at any time, by volume or year. Current price is US $50.00 per volume. Numbers of Palaeontographica Americana are priced individually, and are invoiced separately on request.
for additional information, write or call:
Paleontological Research Institution 1259 Trumansburg Road Ithaca, NY 14850 USA
(607) 273-6623 FAX (607) 273-6620
(@) This paper meets the requirements of ANSI/NiSO Z39.48-1992 (Permanence of Paper).
MCZ LIBRARY
ILUME 106, NUMBER 345 JUNE 3, 1994
Silurian Radiolarian Zonation for the Caballos Novaculite,
Marathon Uplift, West Texas
by
Paula J. Noble
Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York, 14850 U.S.A.
ISSN 0007-5779 ISBN 0-87710-434-6 Library of Congress Catalog Card Number: 94-654807
Printed in the United States of America Allen Press, Inc. Lawrence, KS 66044 U.S.A.
TABLE OF CONTENTS
Abstract :
Acknowledgments
Introduction . ,
Regional Setting and Structural Eramew one oes ihe cyte wen teenies ates
Caballos Novaculite
Sample Localities. . .
Previous Work :
Method of Sample Brepaion’
itects of ereservation Bias! s. 46 c..2e- sie tees ese Be Oh been fot me aren eS aes
Radiolananezones ofthe Gaballos Novaculite) .2 222.2466 smels see iene eel
ROtasphacnid i SuperzOne (RO) ee ese: see cele cucscree siephers ie eacteet ste iene eyemeres : :
Zone |. Palaeoactinosphaera (?) asymmetrica Lares Creme Tone 2 Zone 2. Praespongocoelia Taxon Range Zone erie icbie ac dage tae itay acetone apsievege hs Zone 3. Praespongocoelia—Stvlosphaera (2) magnaspina Partial Range Zone .. . Zone 4. Stylosphaera (?) magnaspina Taxon Range Zone. Perera Zone 5. Rotasphaeracea—Devoniglansus unicus Partial Range Zone .............
Zone 6. Devoniglansus unicus—Pseudospongoprunum (?) tauversi Interval Zone ............. 000 cece eee eee eee
Chronostratigraphic Assignment Comparison with Other Silurian Radiolarian Faunas Southern Urals, Kazakhstan . Cornwallis Island, Canadian Pachisciare Japan ... ; Be a Peas: i: ae Re ies PIER 2 ee Kurosegawa aiectonic Zane Hob ede eerste Assemblage |. Secuicollacta ? exquisita Agemblice ae Assemblage 2. Pseudospongoprunum tazukawaensis Aecembinre Assemblage 3. Pseudospongoprunum sagittatum Assemblage ........... Soch Assemblage 4. Devoniglansus unicus Assemblage ................... Settsreas ts 2 Fukuji Area, Gifu Prefecture so fols| Spnpttertea soda ataysen sasha Guat eyaeye: eee BoRRe = Fusalfanus osobudaniensis Assemblage . . - PT Cn Oe ero e ee
Praespongocoelia (Spongocoelia) par ar epone merlin (Spongocoelia) kamitakarensis Aecemblare es
Zadrappolus yoshikiensis Assemblage : seta ore te.epevettaiesays easier Stylosphaera ? sp. A-Stvlosphaera ? sp. B Aecomblage 5 Stvlosphaera ? sp. C Assemblage Systematic Paleontology : : : a EAC Introduction |. t OE Corie! Be As Radiolarian Species Goncent 5 Ric Oa GO MA ieee Morphological Terminology Relationship Between the Rotasphaeridae and Pscudorotaephacnidae Class Actinopoda Subclass Radiolaria be LE HOSS Oe ieee Seer Order Polycystida Suborder Spumellariina Superfamily Rotasphaeracea . Family Rotasphaeridae Genus Rotasphaera Genus Secuicollacta. Family Pseudorotasphaeridae ........ 6 esto iets OR ere aCe Genus: Pseudorotasphaera’ 2... 2.2.2 .csie-- esse Aine A nel Shen ae Superfamily Spongodiscacea ...... ; sbsete ieee s seman Family Sponguridae .- Genus Pseudospongoprunum.... Genus Devoniglansus Superfamily Incertae sedis Family Inaniguttidae Genus I/nanihella Genus Fusalfanus ; Genus Oriundogutta ............ Genus Zadrappolus ....... Bie conn ies a ban ee Family Palaeoactinosphaeridae Genus Palaeoactinosphaera................-. Genus Stylactinosphaera .
Family Palacoscenidiidae io. 2/52 er sree OE eos cee ae 37
GENUS GOOADOAI UII asic oD ice CS oe ee TOO EEE OSS EC 37
Genus Oldsworthittne. .2cdacc seis Gite tem novos fs ook ON Te OTS TE ES Oe eee 37
Family: Incentac:Sedis ss osc. u .tysy saeco che coy eu yy 2 scan once epee papers Pee Tee UO eo 37 GOnUSHBIDVIOSPON BIG) Foc. ctas waco desta Soe s Eee rte apse RES PE eT ee 37
Genus: PraesponZOcoelia’: & iasye le. oe Seis rmccs mane 8 AS Teo oo ee ee 38
GENUS" Cen OSD NGO Giese iacs ots areca oR Sasa diay Sere AAA pee RT OE ee 38
GENUS ESL TOSD AGEN s.r srayovsipacsl aS aye eaabis xcs SITS reas snl FTO ee 39
Appendix: Radiolarian)Sample!Descriptions:.. <<, «c.ccca.sa 0 se See nd sin ster oer Wah as are eee ee ee oe 39 FREfErEN CES! CLS fre pena cePet Sy ofa oir aP ERG SS ASL ov SSS ESPON TSH Sve SP EY SSP gy CPN eR see 41 PV At eS ie yore oe zpsrnys aya Re Sees ce sche Phe eve fea aya tesyena fo aus ouc's zp ysutece cla ap ade; <iese bn Suey ebspereuneySTISI& ce eiey eg aT SR tree 44 tl ea eee CC eee errr tne eet eerie aera ete SOT aE EGE MEE AREA AG eRe RIEU ROMA el oe nocouocguance 53
Text-figure Page lenocality:map'for the Marathoniuphift -< 1.25552) sass ocieneoteee ase eset Se e E e S 6 2. Generalized stratigraphy of the Paleozoic Ouachita Front rocks exposed in the Marathon uplift ............................-. a 3:; Eocality:map showing outcrop’ pattern of the’Caballos\Novaculites.-.-<-2 492 02s 4.s-19er 6s sade cee ee ae eee 7 4. Lithostratigraphy of the Caballos Novaculite west of the Dagger Flat Anticlinorium.........................--00----00------ 8 5. Stratigraphic cross section of the lower chert and shale member of the Caballos Novaculite showing lithology and sample
|S) 0-10) 1 peer a eee en peepee pace ee ee ee es Se Se aE A ae oe edo ae SadoGoavercess 10 6. Radiolarian biozonation for the lower chert and shale member of the Caballos Novaculite showing ranges of primary and secondary NAY: 0 <<) th 20, ¢: Ua eee eee eee ee eee ee oes eae ee ee oe ee Sao RRNA eG Sel Peon or Gace ase ce cocooces= 12 7. Correlation of local radiolarian zones in the Marathon uplift with radiolarian assemblages described from Japan and Kazakhstan 15 8. Schematic diagram showing skeletal elements of the Rotasphaeridae ............... 0.00 c cece ccc ecceeceesteusevetevseenees 18 9. Schematic diagram showing skeletal elements of the Pseudorotasphaeridae................0 0 0c cece cece cee eeeeeveeeusevaes 18 lO Schematic'diagram\of the: genera‘inithe family) Inaniguttidae..... ...7-eeeiass soe nee eo eee eee 29 LIST OF TABLES
Table Page 1. Radiolarian taxon occurrence chart for the lower chert and shale member of the Caballos Novaculite...... fold-out inside back cover) 2: Skeletallmeasurements for Rotasphaera becKwithensiS’ 2 2c oe es 0c soe cas ne « dace ose ee eee dee ae cee eee 20 35 Skeletallimeasurements' for Rotasphaeraidelicata 05.222 ee. sees) ie ieee oe eee oe 21 4. Skeletal measurements for Rotasphaera marathonensis ....... so: isha Gr tts fd 3 Glace aC ace na SSSI Ores Ce eee ee 21 5. Skeletal measurements for Rotasphaera nuda ....... gl lgusta/ene ig: Sudte, ereiegue) 8) 8.8 08 Stole Woe. 4,2 Soe-e suiaue pes AIC asa OSCE eee 21 6. Skeletal measurements for Rotasphaera quadrata . - ae Reese Li soph oe aa gy eveyev'ugns,avavescyayate elena anyats Cleese eee 22 7. Skeletal measurements for Rotasphaera robertsorum........ ere eee F Sta. o03 gays teen debe tekeaei ge OSE fee Ee oe 22 8. Skeletal measurements for Secuicollacta cassa? . . : Meer cme macre és ee) over doors Se ianere St Saas Lee eee 23 9. Skeletal measurements for Secuicollacta foliaspinella aif te Lepsius okey ces gs cou trey ie Vokst use yspeesh chose iatayaces ease apa A ee ee 24
10. Skeletal measurements for Secuicollacta (?) platyspina BSc Sear ieee susaceserbse.gye.everugte oe eterere tue Bees Se eee 24
11. Skeletal measurements for Secuicollacta solara..... ates ence beala( sini mabe ly oes yStorendva one eeaeyle Ok ghehe Sapo Ae 24
2" Skeletallimeasurements for Pseudorotasphaera hispidas... =... suassadesdeeen seen. teen een een eee 26
13. Skeletal measurements for Pseudorotasphaera communa ee ost eee ons, tt ahs AG dsl edya.ciss a. toler eeaeaavaeebaey aids ee EEE Ee 26
14. Skeletal measurements for Pseudorotasphaera lanceolata ...... oe sis sirbigiS See Sh0i’ (eo eheir iefentiracs enaeS yo eRe ee eS ie ee ee 26
15. Skeletal measurements for Pseudorotasphaera (2) robustispina . RS eee otis fahayayc Savana (oak avdraltapatnal caro tee 27
16. Skeletal measurements for Pseudorotasphaera (?) rotunda ...... Been Ea Rees a2 Se ERs rs 8 omar Pa)
17. Skeletal measurements for Pseudospongoprunum (?) tauversi. . é afin ¥ Fins. 8 SiG ers) owls TAR Sreveenoaye et Rel leo ORS Sree 28
18. Skeletal measurements for Oriundogutta (?) kingi Pee oer si ave cavavohayls: eioyeve fayh ganeh egeesaspece as ioes ben get ea Ree Ree 31
19. Skeletal measurements for Oriundogutta (?) varispina....................--.. ee ne ee AR ie - 32
20. Skeletal measurements for Zadrappolus lunaris .............. oe eiats aie Saye bi9: pithy eRe Gibe Sgyea ede p ORS EIR eee 32
21. Skeletal measurements for Palaeoactinosphaera antica . . . eee eee Hemera ees Pea. IO os so vendes 34
22. ‘Skeletal’ measurements for Palacoactinosphaera aSVMMetric.. 4.024.144.6044 4ste eee eee eee ee 34
23. Skeletal measurements for Palaeoactinosphaera barricki ....... o. Brdrd.3 418.16 -SURT abs bdr eis ¥r8 SPEBSIS DIES ARNIS STL 34
24. Skeletal measurements for Palaeoactinosphaera (?) crucispina. . . siatdhinaterevace Gistotave eee Gree eee ee eee 35
25. Skeletal measurements for Palaeoactinosphaeralelegantissim@ 2 s.20).422.52-4 2662 e see eee eee eee eee eee 35
26. Skeletal measurements for Palaeoactinosphaera (?) octaspina ...... Ree ats Done oboe sob DS Gacea 36
27. Skeletal measurements for Stylactinosphaera prima.............. ee ee eae a Gte Ane Oc on oon etou oon Gabeoo neue 36
28. Skeletal measurements for Bipylospongia rudosa ..... ens oes a) bus. @rand eaceverelare muaeiaabeyaic ate emir aan dere 37
29. Skeletal measurements for Praespongocoelia fusiforma ........... deans brig bode vie ay Sestenenele se ete area aha one eae Se eee 38
S02 Skeletalimeasurements) for Stylosphaerai(?) masnaspindes 52. 4.4.2 nee ee ee 39
SILURIAN RADIOLARIAN ZONATION FOR THE CABALLOS NOVACULITE, MARATHON UPLIFT, WEST TEXAS
PAULA J. NOBLE
The University of Texas at Austin Department of Geological Sciences Austin, TX 78712!
ABSTRACT
This paper presents a local biozonation for Silurian radiolarians recovered from the Caballos Novaculite, Marathon uplift, Texas. Six measured sections representing 25-30 m of strata from the western half of the uplift have yielded abundant and moderately well-preserved radiolarian assemblages that can be subdivided into six biozones. The Rotasphaerid Superzone (Ro), contains the four oldest zones 1, 2, 3, and 4, and is defined by the first and last appearances of the superfamily Rotasphaeracea. The base of this superzone has not yet been determined in the Marathon uplift. All taxa chosen for this biozonation are commonly occurring, distinctive, robust forms that can be correlated from section to section, thereby meeting the criteria for establishing a practical and widely applicable biostratigraphic scheme.
Three conodont assemblages co-occur with the radiolarians and show the youngest zone to be no younger than Pridolian (Late Silurian). The oldest zone, Zone 1, is at least as old as Ludlovian and may be as old as Wenlockian (Early Silurian). Further chronostratigraphic calibration is needed to constrain the ages of these radiolarian zones better.
Taxa from the Ro Superzone bear strong resemblance to Silurian radiolarian assemblages from the Canadian Archipelago and Southern Urals, and are identical to forms described from the Fusalfanus osobudaniensis through Stylosphaera ? sp. C assemblages from the Fukuji Area, Gifu Prefecture, Japan. Several taxa in the lower part of Zone 6, above the Ro Superzone, are identical to those in the Devoniglansus unicus assemblage from the Kurosegawa Tectonic Zone, southwest Japan. The widespread geographic distribution of these assemblages suggests that it may be possible to generate a global radiolarian biozonation for the Silurian period.
Various biostratigraphically useful Silurian radiolarians are described in this paper. One new superfamily, three new families, six new genera, and 28 new species are described. The new superfamily Rotasphaeracea includes the new families Rotasphaeridae and Pseudorotasphaeridae. Within the Rotasphaeridae are the genera Rotasphaera, n. gen. containing R. beckwithensis, n. sp., R. delicata, n. sp., R. marathonensis, n. sp., R. nuda, n. sp., R. quadrata, n. sp., and R. robertsorum, n. sp., and Secuicollacta Nazarov and Ormiston, containing S. cassa ? Nazarov and Ormiston, S. foliaspinella, n. sp., S. solara, n. sp., and S. (?) platyspina, n. sp. Within the Pseudorotasphaeridae is Pseudorotasphaera, n. gen., containing P. communa, n. sp., P. hispida, n. sp., P. lanceolata, n. sp., P. (?) robustispina, n. sp., and P. (?) rotunda, n. sp. The new family Palaeoactinosphaeridae contains Stylac- tinosphaera, n. gen., with S. prima, n. sp., and Palaeoactinosphaera, n. gen. containing P. antica, n. sp., P. asymmetrica, n. sp., P. barricki, n. sp., P. (?) crucispina, n. sp., P. elegantissima, n. sp., and P. (?) octaspina, n. sp. Other new taxa described are Pseudospongoprunum (?) tauversi n. sp., Praespongocoelia n. gen., containing P. fusiforma, n. sp. and P. parva Furutani, Bipy- lospongia, n. gen. containing B. rudosa, n. sp., Stylosphaera (?) magnaspina, n. sp., Oriundogutta (?) kingi, n. sp., Oriundogutta (?) varispina, n.sp., and Zadrappolus lunaris, n. sp. Systematic revisions of the following taxa also are included: Genus Secuicollacta Nazarov and Ormistonm and its type species, Secuicollacta cassa, Family Inaniguttidae Nazarov and Ormiston and its genera Inanigutta Nazarov and Ormiston, /nanihella Nazarov and Ormiston, Fusa/fanus Furutani, Zadrappolus Furutani, and Oriun- dogutta Nazarov and Ormiston, in addition to Spongocoelia parvus Furutani, Fusalfanus osobudaniensis Furutani, and Pseu- dospongoprunum, Wakamatsu et al.
ACKNOWLEDGMENTS
Field work in west Texas was funded by grants from the Geological Society of America, the Geology Foun- dation at The University of Texas at Austin, the Gulf Coast Association of Geological Societies, and Sigma Xi. Publication funds were provided by the Owen- Coates Fund of the Geology Foundation at The Uni- versity of Texas at Austin. The Gretchen L. Ble- chscmidt grant received from the Geological Society of America and the Hendricks grant received from the American Association of Petroleum Geologists helped
‘Current Address: Geology Department, California State Uni- versity Sacramento, Sacramento, CA 95819-6043.
finance a visit to Nagoya University for the study of the type Silurian radiolarians deposited by Dr. H. Fu- rutani and Mr. H. Wakamatsu. I am greatly indebted to Drs. S. Mizutani and S. Kojima and to Mr. K. Su- giyama and Ms. H. Nagai of Nagoya University for their assistance with the collections. I thank Jim Hayne and Ike Roberts of the Paisano Cattle Company, Travis and Polly Roberts of the Roberts Ranch, Gage Hol- land, Ann, and Mark Daugherty of the Gage Ranch, and Bob McKnight for permitting access to field areas. This manuscript was greatly improved by the com- ments and criticisms provided by the reviewers, Jon C. Aitchison and Charles D. Blome. I also thank Rich- ard E. Casey, Martin B. Lagoe, Brian K. Holdsworth, William R. Muehlberger, and Emile A. Pessagno, Jr.
6 BULLETIN 345
OUACHITA MTNS
GULF OF MEXICO
SOLITARIO
MEXICO fea
Text-figure 1.—Locality map for the Marathon uplift showing its position at the southwestern extent of the Ouachita Front, Big Bend region, west Texas. Shaded area denotes outcrop areas of the Ouach- ita Front.
for helpful discussions and useful suggestions on earlier drafts of the manuscript, and thanks to Laura Brock who assisted me in the field.
INTRODUCTION
Paleozoic radiolarian studies is a relatively young field that has grown over the last decade into a dynamic area of research with valuable biostratigraphic and pa- leoecologic application (Jones and Murchey, 1986). In the early 1980’s, biozonal schemes were first intro- duced for Late Devonian and younger rocks (Hold- sworth and Jones, 1980; Ishiga et a/., 1982). Since that time, an increasing number of detailed Late Paleozoic radiolarian studies have been published (e.g., Won, 1983; Nazarov and Ormiston, 1985; Cheng, 1986). In contrast, early Paleozoic radiolarians have remained relatively unstudied, with the ranges of taxa uncertain and poorly dated. As a consequence, there are large gaps in the existing Paleozoic biozonations and no comprehensive radiolarian zonation exists for the Si- lurian through Middle Devonian.
The few published works on Silurian radiolarians have documented unique and diverse assemblages which show potential for generating a useful biostrati- graphic scheme for the early Paleozoic. Silurian radi- olarians have been described from Japan (Furutani, 1990; Wakamatsu et a/., 1990; Aitchison, 1991), Aus- tralia (Aitchison, 1990), the Canadian Archipelago (Goodbody, 1986; Renz, 1988), and Kazakhstan (Na- zarov, 1975). Several workers have been able to place their assemblages in a stratigraphic context, yet a num-
ber of the studies are detailed accounts of taxa from isolated samples, or samples collected from poorly ex- posed and faulted sections. Although these studies are good surveys of the potential diversity of early Paleo- zoic faunas, they provide limited biostratigraphic in- formation. The data presented herein from the Mar- athon uplift are critical to the development of a comprehensive early Paleozoic biostratigraphic scheme because they have been collected from a number of structurally continuous measured sections where stratigraphic relationships between radiolarian assem- blages can be recognized.
REGIONAL SETTING AND STRUCTURAL FRAMEWORK
The Marathon uplift exposes deformed Cambrian through Pennsylvanian marine sedimentary strata be- lieved to have been deposited in a parautochthonous basin located along the rifted southern paleocontinen- tal margin of North America (Arbenz, 1989). These rocks are exposed in a topographic depression, the 3500 square km Marathon Basin, located approximately 50 km north of Big Bend National Park (McBride, 1989). The basin is rimmed by Cretaceous carbonates to the east, south, and west, and by the Permian Glass Moun- tains to the north-northwest. The Marathon uplift is part of a larger feature, the Ouachita orogenic belt, a sinuous, mainly subsurface belt that extends from the Big Bend Region of Trans-Pecos Texas to east-central Mississippi (Flawn ef a/., 1969; Text-figure 1). The Ouachita orogenic belt was deformed synchronously with the Appalachian System in the Carboniferous— Permian Ouachita orogenic phase caused by the con- vergence of proto-North America (Laurasia) with Gondwana (Ross, 1979). Rocks of the Ouachita oro- genic belt crop out only in the Marathon uplift, Per- simmon Gap area, and Solitario uplifts of west Texas, and in the Ouachita Mountains of Oklahoma and Ar- kansas.
Two stages of deposition are recognized in the Mar- athon uplift on the basis of sediment composition and rate of deposition; a slowly deposited pre-orogenic stage and a more rapidly deposited syn-orogenic (flysch) stage (Thomson and McBride, 1964). The rocks deposited during the pre-orogenic stage are Cambrian-earliest Mississippian and are characterized by extremely low rates of deposition producing approximately 1000 m of shales, chert, limestone, and minor sandstone over a 200 million year period (Text-figure 2). The syn- orogenic stage, starting in the late Mississippian, 1s characterized by high rates of deposition producing a thick clastic wedge of approximately 4000 m thickness deposited in only 60 million years (McBride, 1989). Paleocurrent indicators and overall geometry of the syn-orogenic strata indicate that the dominant source
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 7
Formation
Conglomerate
(IBSPTRSEAS is Limestone pees <EREEEEES Siltstone/ SSISISISS Sandstone ECR veiietelt — Novaculite poets | BS coremcace, Bedded chert Formation edded che => Poe sf = poets | B pn sh > Sececerr ale —J RosnaSenEl | o2 SESEESEoS zo sesso ig seserese 3 co | Pennsylvanian Dimple ar =a Limestone -_ 4h £ Se ee o) -———-
Tesnus Formation
[__Devonian Caballos Novaculite Maravillas oor Formation = Woods Hollow Ordovician Shale
Ft. Pena Fm
Marathon Limestone fy : sererstointelea] Cambrian Dagger Flat [77] Sandstone [--.-.-.-.| ——————
Text-figure 2.—Generalized stratigraphy of Paleozoic Ouachita Front rocks exposed in the Marathon uplift. The pre-orogenic se- quence was deposited along a rifted passive margin, whereas the flysch sequence was deposited syn-orogenically during the Ouachita orogeny.
MUCH UE
of terrigenous clastic debris, in particular, the source for the Tesnus and lower Haymond, came from the southeast (McBride, 1966; Cotera, 1969). Some of the clastic input during the syn-orogenic stage, however, did come from the north and northwest. A northern
EASTERN DOMAIN
SOUTHERN DOMAIN
8 km
Text-figure 3.—Locality map showing outcrop pattern of the Ca- ballos Novaculite in gray, modified from King (1937). Heavy gray dotted line separates structural domains of Muehlberger (1978). Measured sections: PH = Payne Hills, PH2 = Payne Hills II, SS = Sulphur Springs, MC = Monument Creek, MA = McKnight, EB = East Bourland, WH = Wood Hollow. See Appendix for the precise location of each section.
source is proposed for the Dimple Limestone, a cal- carentite sandwiched in between the Tesnus and Hay- mond formations (Thomson and Thomasson, 1969), and olistostromal blocks that occur in the base of the Tesnus Formation in the western basin margin can be traced to North America (McBride, 1978). The size of the Tesnus olistoliths also indicates that the basin had to be in close proximity to continental North America to allow for their transport.
The rocks exposed in the Marathon uplift have been folded and thrusted into a series of anticlinoria- syn- clinoria and imbricate stacks of thrust sheets trending NE and showing transport to the NW (King, 1937; Flawn et al., 1961). The structural grain is well illus- trated by the outcrop pattern of the Caballos Novac- ulite (Text-figure 3). Three structural domains are rec- ognized in the uplift based on the deformational style and the rheology of the rocks exposed (Muehlberger, 1978; Muehlberger and Tauvers, 1989). The western
8 BULLETIN 345
upper chert and shale member (DC5)
upper novaculite member (DC4)
lower chert and shale member (DC3)
studied Y interval
lower novaculite member (DC2)
lower chert (DC1)
Text-figure 4.—Lithostratigraphy of the Caballos Novaculite west of the Dagger Flat Anticlinorium. Unit abbreviations follow Mc- Bride and Thomspon, 1970. See Text-figure 2 for an explanation of the lithologic symbols.
domain is characterized by exposures of tightly-folded, pre-orogenic strata overlain by a thin (1000 m) se- quence of syn-orogenic strata, whereas the eastern do- main exposes thick (3000 to 5200 m) sequences of broadly-folded syn-orogenic strata. The southern do- main consists of imbricate stacks of thrust sheets, com- posed principally of syn-orogenic strata. Within the western domain, Muehlberger and others have been able to estimate degree of structural shortening; the strata west of the Dagger Flat Anticlinorium have been shortened by approximately 2:1 and the Dagger Flat Anticlinorium has been shortened by as much as 6.2:1 (Coley, 1987; Muehlberger 1990, 1991).
CABALLOS NOVACULITE
The Caballos Novaculite is the youngest unit de- posited during the pre-orogenic stage. It is a highly condensed biosiliceous unit that is underlain by the Late Ordovician Maravillas Limestone and overlain by the late Mississippian to Pennsylvanian Tesnus For- mation. The formation is lenticular in shape with a maximum thickness of 210 m but generally ranges between 65 and 150 m (McBride and Thomson, 1970). The Caballos Novaculite is subdivided into five mem- bers, each consisting of one of two lithologies; medium- bedded spiculitic novaculite and rhythmically bedded chert and shale (Text-figure 4). The novaculite mem- bers are commonly milky-white, highly resistant, bench-and ridge-forming units. Both the lower and up-
per novaculite members vary in thickness and in some areas are entirely absent. Their characteristic white col- or is derived from the near absence of clay or impurities (Folk, 1965; McBride and Thomson, 1970). The chert and shale members are slightly less resistant than the novaculite, forming slopes and ridges. They consist of rhythmically bedded varicolored chert, shale, and por- celanite that contain varying amounts of clay, iron oxides and other impurities. The chief biogenous com- ponents in the chert and shale members are radiolar- ians, although some spiculitic beds occur. The upper- most member becomes progressively shalier up section and grades into the lower olive to black colored shales and siltstones of the Tesnus Formation.
The recovery of Silurian radiolarians and conodonts provides important biostratigraphic control for the Ca- ballos Novaculite. Until recently, the Caballos had yielded only a small amount of biostratigraphically useful information, chiefly in the form of conodonts recovered from the uppermost member of the for- mation (Graves, 1952; Barrick, 1987). The lower half remained undated and it was unclear whether the Si- lurian was present at the base of the Caballos in con- densed form (e.g., Thomson and McBride, 1964; McGlasson, 1967), or if it was missing, cut out at a disconformity at the Maravillas-Caballos boundary (e.g., Baker and Bowman, 1917; King, 1937). The bio- stratigraphic data presented herein answers this long- standing question by providing the first documentation of Silurian strata in the Marathon uplift. Silurian con- odonts and radiolarians recovered from the lower chert and shale member show that half of the formation is Silurian. The Caballos Novaculite is therefore shown to be a long-lived record of siliceous sedimentation, uninterrupted by significant pulses of clastic input, that spans from the Silurian through the earliest Mississip- pian, a period of over 70 Ma.
The improved age control afforded by radiolarians and conodonts makes several important contributions to the regional geology. First, it allows the members of the Caballos to be correlated more precisely to Si- lurian—Devonian North American continental shelf deposits in the subsurface of west Texas (Noble and Barrick, 1991; Noble, 1993a) and in doing so, helps to provide a clearer picture of the Silurian—Devonian de- positional history along the southern paleo-continental margin of North America. Second, understanding the relationship between shelf and basinal facies may help answer questions concerning the environment of de- position of the Caballos Novaculite. The factors con- trolling deposition of the novaculite members has been a subject of considerable interest and debate; interpre- tations have ranged from deposition in a peritidal set- ting (e.g., Folk, 1973; McBride and Folk, 1977) to de- position in a deep marine setting (e.g., Thomson, 1964;
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 9
McBride and Thomson, 1970; Folk and McBride, 1976; McBride and Folk, 1977). Work in progress that com- bines detailed biostratigraphy with sedimentology and paleoecology may shed further light on this subject. Third, the biozones have the potential to aid greatly in the structural interpretation of complex parts of the basin where stratigraphic relations have been obscured by folding and faulting. For example, the absence of the lower novaculite member in parts of the Payne Hills at the western basin margin has been previously interpreted to be caused by structural attenuation (McBride, 1978). Biostratigraphy of the areas in ques- tion show that the absence of the lower novaculite is not structurally controlled but caused by a facies pinch- out of the lower novaculite (Noble and Barrick, 1991; Noble, 1993b). Further fine-tuning of these biozones and calibration with chronostratigraphic data will cre- ate a powerful tool which can be applied to understand better the structural styles and depositional history of the Marathon uplift during the Silurian—Devonian.
SAMPLE LOCALITIES
The data set for this study comes from seven mea- sured sections of the basal 10 to 25 m of the lower chert and shale member of the Caballos Novaculite. These sections were chosen for their stratigraphic con- tinuity and completeness. Additional sections were sampled during the reconnaissance process but are not included in this report because of their structural com- plexity and uncertain stratigraphic position. All sec- tions occur in the western part of the uplift, westward of the Dagger Flat Anticlinorium (Text-figure 3). Little data were recovered eastward of the west limb of the Dagger Flat Anticlinorium (ridge containing WH sec- tion), due in part to poor exposure and poor fossil recovery, and in part to lack of access to private prop- erty. Radiolarians are sufficiently abundant, distinc- tive, and well-preserved to allow for the recognition of six biozones which can be traced from section to section across the basin. All biozones described occur within a minimum of two measured sections. Locality and sample descriptions are found in the Appendix.
Samples were collected during six field excursions conducted from November of 1987 through September of 1990. A reconnaissance trip in November of 1987 determined that fossiliferous samples could not be rec- ognized reliably in the field. Whereas radiolarians are sometimes visible in the field with the aid of a 14x hand lens and appear as glassy spheres, radiolarians in the Caballos samples are seldom visible. Some glassy spheres were observed in hand specimen, but labora- tory work later identified them as cristobalitic lepis- pheres, not fossils. Other samples that appeared to be barren of radiolarians in the field produced well-pre- served specimens when processed in the lab.
Since fossils could not be observed in the field, a variety of sampling strategies were employed to max- imize fossil recovery. Some sections were sampled in great detail on a bed-by-bed basis over several meter intervals (e.g., Payne Hills I] section) and other sections were sampled by collecting composite samples of two to four adjacent beds at 50 cm intervals to increase chances of recovery. Composite samples are indicated by a “‘c” following the sample number (Text-figure 5). Some of the productive sections that were sampled by the composite method were later re-sampled for single bed samples (e.g., Monument Creek). Access to parts of the field area became restricted in 1989 and limited the amount of re-sampling. Limited access was allowed for a finite number of excursions in 1990, during which I focused on collecting from unsampled and under- sampled localities.
Composite sampling, while necessary to insure fossil recovery, is potentially problematic because it may condense two or more temporally distinct assemblages into one sample. If composite assemblages combine strata equivalent to a long time interval they can ar- tificially extend stratigraphic ranges and may falsely portray an overlap of ranges for taxa that do not ac- tually overlap in time. Composite sampling effectively reduces the resolution of the data set and limits the degree of biostratigraphic subdivision possible. De- spite the fact that half of the samples are composites, the lower chert and shale can be finely subdivided and successfully correlated biostratigraphically. Should fu- ture access be permitted, additional re-sampling by the single-bed method can be used to test further for the mixing of assemblages in composite samples and may serve to allow for an even greater degree of biostrati- graphic resolution.
PREVIOUS WORK
Aberdeen (1940) described 32 new species of radi- olarians from thin-sections of the Caballos Novaculite. The studied material came from two samples collected by P. B. King from the Santiago Member of the Ca- ballos Novaculite. The Santiago Member originally re- ferred to the rhythmically bedded chert and shale that overlies the novaculite. The name Santiago Member is no longer in use, since it has been demonstrated that two distinct novaculite horizons exist throughout much of the basin. Aberdeen provides no precise locality information, but based on the forms illustrated in her work, the samples appear to be from the lower half of the lower chert and shale, within the Rotasphaerid Superzone.
It is difficult to incorporate Aberdeen’s taxonomic scheme into the one employed in this paper. Aber- deen’s taxa were described entirely from cross-sec- tional views in thin-section, and many are not recog-
BULLETIN 345
10
Wood Hollow
MC Monument Creek
PH Payne Hills
ae} i= a a5 rey i @ q wu
Ss Sulphur Springs
Te Se ae &
nyUsIER
MA McKnight
1
uli
g
ga
407c
403 40 }00 399 398 397
"S. g'g g.2 5 2
/ if
7
ba} 8
“2
. Y i We AGA:
o Bll
unzoned
Zone
396c
SIS
S \ 3 3\
°
=
Fe ee Bean
212¢
it
LA Pseudospongoprunum tauversi
FA &LA Stylosphaera (?) magnaspina
FA Devonglansus unicus
LA Rotasphaeracea LA Praespongocoelia
Arenaceous
chert
oy Limestone eee Conglomerate
Wavy bedded
chert
== Shale
Bedded
[ira] Novaculite =|
chert
FA Praespongocoelia
FA Palaeocactinsphaera asymmetrica
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 1]
nizable in matrix-free samples. The cross-sectional view of radiolarians seen in her thin-sections is inadequate for descriptive taxonomy, as it provides no view of surface textures and does not allow for the determi- nation of the number and symmetry of spines. Aber- deen’s type specimens from the Caballos were exam- ined by Riedel and Foreman (1961) who more accurately located each type specimen in thin-section with the aid of an England Finder, a gridded 3” = 1” glass slide divided into 1 mm squares. Riedel and Fore- man noted the relative abundance of all taxa that they were able to locate and provided useful sketches of several taxa they observed in thin-section. Wherever possible, Aberdeen’s taxa have been incorporated into the taxonomic scheme presented here. Synonymies are discussed for those taxa which can be reliably deter- mined to be conspecific with the taxa described herein.
METHOD OF SAMPLE PREPARATION
All samples were recovered from radiolarian cherts by etching in dilute hydrofluoric acid for a 24 hour period (Pessagno and Newport, 1972). Individual ra- diolarians liberated from the matrix by the dilute etch- ing were washed and sieved at 63 and 108 micron fractions. Some samples were cleaned by heating in 30% hydrogen peroxide for five minutes. The hydrogen peroxide bath proved destructive to specimens in the less well-preserved samples and was only used when necessary on well-preserved faunas. Radiolarians were picked from dried residues and identified with the aid of reflected light, transmitted light, and scanning elec- tron photomicroscopy. All photos were taken using a Jeol JSM-T330A scanning electron microscope and a Nikon polarizing microscope with photomicrographic attachment. Measurements were made with the aid of an objective micrometer mounted in the occular of a Wild reflected-light microscope.
EFFECTS OF PRESERVATION BIAS
Radiolarian assemblages recovered from the Cabal- los Novaculite are preservationally biased towards the more robust forms. Typically, radiolarian assemblages extracted from siliceous lithologies have a strong pres- ervational bias because of the diagenetic effects of cher- tification and the destructive chemical extraction tech- nique that employs hydrofluoric acid to liberate the fossils from the siliceous matrix (Blome and Reed,
1993). Radiolarians extracted from limestones and carbonate or phosphatic concretions are generally much better preserved that those recovered from siliceous rocks (Blome and Albert, 1985; Blome and Reed, 1993), yet volumetrically, most Paleozoic radiolarians occur in siliceous lithologies such as porcellanites, cherts, siliceous mudstones, or argillites. Some delicate spic- ular taxa characteristic of well-preserved Silurian as- semblages recovered from limestones and concretions are rare in the Caballos samples, and because of their sporadic occurrence, are not used as marker taxa in this biozonal scheme.
An important consideration in erecting any bio- stratigraphic scheme is its applicability. The radiolar- ian biozonation presented herein is designed specifi- cally for use on siliceous rocks. All taxa chosen are robust, distinctive, common, and short-ranging, there- by meeting the requirements for practical application to siliceous rock units. Their potential application to calcareous rocks or phosphatic concretions is untested and may be limited, however, because of the marked differences caused by differential preservation.
Preservational biases may also play a significant role in how the taxonomic framework is initially erected. Internal structure and wall construction are two char- acteristics which are considered to be critical in deter- mining the phylogenetic relationships of Spumellariina (Pessagno, 1977). It is often difficult to analyze the internal structures when working with chert residues. Radiolarians are frequently filled with microcrystalline quartz or chalcedony which obliterates the delicate in- ternal structure (Pl. 4, fig. 5) and only rarely, are the internal structures preserved. Considerable attempts have been made to find specimens that have the in- ternal structure preserved. Wherever possible, reflect- ed light microscopy has been used to illustrate these features better (Plates 8, 9). Quite frequently, the in- ternal structure is reflected in external features, such as in the number and symmetry of spines. Taxa whose internal structures could not be determined have been provisionally classified at higher taxonomic levels us- ing other external skeletal characteristics.
RADIOLARIAN ZONES OF THE CABALLOS NOVACULITE
A number of biohorizons, defined by either the first or last appearance (FA or LA) of a distinct and robust taxon, have proven useful in biostratigraphic correla-
—
Text-figure 5.—Stratigraphic cross section of the lower chert and shale member of the Caballos Novaculite showing lithology and sample horizons. Samples with a “‘c’”’ following the number are composite samples of 2 or 3 adjacent beds within a 30 to 130 cm interval. Lines of correlation are the radiolarian biohorizons (first and last appearance datums) used to construct the local biozonation. Cross section is hung on the base of the lower chert and shale member. See Text-figure 3 for location of individual measured sections.
12 BULLETIN 345
ZONE ZON NUMBER BIOZONE
Devoniglansus unicus - Pseudospongoprunum (?) tauversi
Devoniglansus unicus - Rotasphaera
Stylosphaera (?) m
Praespongocoelia - Stylosphaera (?) magnaspina
Praespongocoelia
Palaeoactinosphaera asymmetrica
Rotasphaerid Superzone (Ro)
|
ABBREV.
PRIMARY MARKER TAXA
SECONDARY MARKER TAXA
O. (?) varispina
| Se Tess Ee
Z. yoshikiensis
P. (?) tauversi
Spumellarian St. (?) magnaspina indet. sp. A
P. asymmetrica P. (?) crucispina
Rotasphaeracea F. osobudaniensis S. prima
Text-figure 6.—Radiolarian biozonation for the lower chert and shale member of the Caballos Novaculite showing ranges of primary and secondary marker taxa. Relative abundances are shown for selected marker taxa. Asterisk (*) denotes the stratigraphic position of conodont
samples | and 2. Shaded area represents an unzoned interval.
tion of the lower chert and shale. Seven of these bio- horizons are used to define the bases and tops of six radiolarian zones (Text-figure 5). At present, the ra- diolarian biozonation presented herein is strictly a lo- cal correlation tool designed to biostratigraphically correlate the lower chert and shale with the most useful and reliable criteria available. It has not been tested outside of the Marathon uplift in order to determine if there are stratigraphic gaps or variations in taxa dis- tribution. As further data on Late Silurian radiolarians is gathered, the zonal scheme presented herein can be compared to other locally devised zonal schemes in order to build a comprehensive Silurian radiolarian biozonation with geographically widespread applica- tion.
All zones are defined in accordance with the Inter- national Guide to Stratigraphic Nomenclature (ISSC, 1976; ISSC in press). Two of the zones are taxon range zones and four of the zones are types of interval zones. Principle marker taxa used in defining each zone ap- pear in Text-figure 6 along with secondary marker taxa. The occurrence of all taxa described in this paper can be found in Table 1. The basis for the chronostrati- graphic calibration of these zones is discussed in the section entitled Chronostratigraphic Assignment. The definitions of the types of zones used herein, as defined by the ISSC (in press), are as follows:
Taxon Range Zone.—The body of strata representing the known range of occurrence of specimens of a particular taxon.
Interval Zone.—The body of fossiliferous strata be- tween two specified biohorizons. The base or top of an interval zone may be the lowest occurrence of a taxon, the uppermost occurrence of a taxon, or any other distinctive biostratigraphic feature (biohori- Zon).
Lowest-Occurrence Zone.—An interval zone repre- senting the strata between the lowest occurrences of two specified taxa.
Partial Range Zone.—An interval zone that partitions the range of a taxon so that the base is defined by the uppermost occurrence of one taxon and the top is defined by the lowermost occurrence of a second taxon; the ranges of the boundary taxa do not over- lap. The name for a Partial Range Zone may be derived from the names of the boundary taxa or or from the name of the taxon whose range was par- titioned.
The use of interval zones whose identification relies on the absence of distinctive taxa is controversial. A Partial Range Zone is one such zone that is distin- guished from underlying and overlying taxa by the absence of the boundary taxa. Absences are not always
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 13
a reliable means of correlation because they can be controlled by preservation and paleoecologic con- straints. Two Partial Range Zones are used herein bea- cause they are believed to be the most useful means of biostratigraphic subdivision for the interval of study. The boundary taxa for these Partial Range Zones have been chosen specifically because they are first and last occurrences of robust, commonly occurring taxa. These taxa are sufficiently robust so that they would be less affected by preservational biases than most other taxa with which they co-occur. They are the most distinc- tive and easily identified biohorizons recognized in the lower chert and shale and are the most useful criteria available for biostratigraphic correlation.
ROTASPHAERID SUPERZONE (RO)
This zone is defined by the presence of the Rotas- phaeracea. The base of this zone is not recognized in the Marathon uplift. The top is defined by the last appearance of members of the Rotasphaeracea. Four biozones can be recognized within the Rotasphaerid Superzone; two taxon range zones, and two interval zones (Text-figure 6).
Zone 1: Palaeoactinosphaera (?) asymmetrica Lowest Occurrence Zone (Pa) (Equivalent to Rol Zone of Noble and Barrick, 1991)
The base of this zone 1s defined by the first appear- ance of Palaeoactinosphaera (?) asymmetrica, n. sp. The top is defined by the first appearance of Praespongo- coelia, n. gen. Taxa that are common but not restricted to this zone are Palaeoactinosphaera (?) crucispina, Nn. sp., Bipylospongia rudosa, n. sp., Stvlactinosphaera prima, n. sp., Pseudorotasphaera hispida, n. sp., Pseu- dorotasphaera lanceolata, n. sp., and Fusalfanus oso- budaniensis Furutani, 1990. The upper part of this zone 1s distinguished from the lower part of Marathon uplift Zone 2 only by the absence of Praespongocoelia.
Age: Silurian (Wenlockian—Ludlovian)
Zone 2: Praespongocoelia Taxon Range Zone (Pr) (Equivalent to Ro2 of Noble and Barrick, 1991)
The base and top of this zone are defined by the first and last appearance of the genus Praespongocoelia. Three species of Praespongocoelia occur within the zone, two of which are described in this paper; P. parva Furutani, 1990 and P. fusiforma, n. sp. Fusalfanus osobudaniensis, Palaeoactinosphaera (?) crucispina, Bipylospongia rudosa, and Stylactinosphaera prima make their last appearance in the lower part of this zone, and Palaeoactinosphaera (?) octaspina, n. sp. makes its first appearance towards the top of this zone. Other taxa which are common, but not necessarily restricted to this zone, include Palaeoactinosphaera
elegantissima, n. sp., Pseudorotasphaera (?) robustis- pina, n. sp., Rotasphaera marathonensis, n. sp., Pa- laeoactinosphaera barricki, n. sp., Rotasphaera beck- withensis, n. sp., Pseudorotasphaera hispida, n. sp., and Pseudorotasphaera (?) rotunda, n. sp.
Age: Silurian (Wenlockian—Ludlovian)
Zone 3: Praespongocoelia—Stylosphaera (?) magnaspina Partial Range Zone (Pr—Sm)
This zone represents a portion of the range of the Rotasphaeracea. Its base is defined by the last appear- ance of Praespongocoelia and the top by the first ap- pearance of Stylosphaera (?) magnaspina, n. sp. Zad- rappolus tenuis Furutani, 1990 makes its first appearance near the base of this zone and becomes very abundant at the top. Many of the taxa occurring in this interval occur in both underlying and overlying zones. Common taxa include abundant Rotasphaera and Pseudorotasphaera, such as R. quadrata, n. sp. and Ps. communa, n. sp., and a progressive increase towards the top of the zone in the abundance of In- aniguttidae, particularly Zadrappolus Furutani, 1990.
Age: Silurian (Wenlockian—Ludlovian)
Zone 4: Stylosphaera (?) magnaspina Taxon Range Zone (Sm) (Equivalent to Ro3 of Noble and Barrick, 1991)
The base and top of this zone are defined by the first and last appearance respectively, of Stylosphaera (?) magnaspina. Also present is a three spined spumel- larian (listed in Table 1 as Spumellarian indet. sp. A) and abundant Inaniguttidae, such as Oriundogutta (?) kingi, n. sp. and Zadrappolus tenuis. Rotasphaera and Pseudorotasphaera are present but are an insignificant part of the assemblage. This interval is very thin and is represented by only two samples in the Marathon uplift.
Age: Late Silurian (Ludlovian—Pridolian)
The following zones overlie the Rotasphaerid Su- perzone:
Zone 5: Rotasphaeracea—Devoniglansus unicus Partial Range Zone (Ro—Du)
This zone represents a portion of the range of the genus Zadrapplous. The base is defined by the last appearance of the Rotasphaeridacea and the top is de- fined by the first appearance of Devoniglansus unicus Wakamatsu ef a/., 1990. This zone includes abundant Inaniguttidae, such as Oriundogutta Nazarov, 1988, Zadrapplous yoshikiensis Furutani, 1990, Zadrappolus tenuis Furutani, 1990, Zadrappolus cf. Z. spinosus Fu- rutani, 1990, and spongy Spumellariina (PI. 5, figs. 13, 14) of uncertain affinity.
Age: Late Silurian (Ludlovian—Pridolian)
14 BULLETIN 345
Zone 6: Devoniglansus unicus—Pseudospongoprunum (?) tauversl Interval Zone (Du) (Equivalent to PRol and PRo2 combined of Noble and Barrick, 1991)
The base of this zone is defined by the first appear- ance of Devoniglansus unicus Wakamatsu et al., 1990 and the top is defined by the last appearance of Pseu- dospongoprunum (?) tauversi, n. sp. Pseudospongopru- num (?) tauversi makes its first appearance near the base of the zone and D. wnicus makes its last appear- ance in the middle of the zone. Other characteristic taxa include Oriundogutta (?) varispina, n. sp., Zad- rappolus lunaris, n. sp., and Zadrappolus spp.
Age: Late Silurian (Ludlovian—Pridolian)
CHRONOSTRATIGRAPHIC ASSIGNMENT
It is rare to find other biostratigraphically useful fos- sils co-occurring with radiolarians in Paleozoic sili- ceous sequences. In the Caballos Novaculite, cono- donts and radiolarians co-occur in the same sample in rare instances, and provide the only means of inde- pendant chronostratigraphic calibration. As a conse- quence, the chronostratigraphic assignment for the de- scribed radiolarian zones is crude. It is based on calibration with three conodont assemblages and by comparison with other documented occurrences of Si- lurian radiolarians (Text-figure 5). Conodonts were found to co-occur in abundance with three radiolarian- bearing samples collected in the vicinity of the Mon- ument Creek section by Dr. Jim Barrick of Texas Tech University. All conodont identifications were made by Dr. Barrick (Noble and Barrick, in prep.). Sample res- idues were mailed to me for radiolarian identification.
Conodont sample | occurs in Zone 3, the Praespon- gocoelia—Stylosphaera (?) magnaspina Zone, and is in- terpreted to be Wenlockian—Ludlovian based on the presence of Dapsilodus praecipuus Barrick, 1977, D. sparsus Barrick, 1977, Walliserodus sp. indet., and Kockelella absidata Barrick and Klapper, 1976. Ra- diolarians identified in this sample are Cenosphaera hexagonalis Aberdeen, 1940, Zadrappolus spinosus Furutani, 1990, Rotasphaera beckwithensis, n. sp., Se- cuicollacta solara, n. sp., and Pseudorotasphaera sp. indet.
Conodont sample 2 occurs at the top of Zone 6, the Devoniglansus unicus—Pseudospongoprunum (?) tau- versi zone, and is interpreted to be Ludlovian—Prido- lian based on the occurrence of Ozarkodina eostein- hornensis ?, Belodella sp. indet., and Dapsilodus obliquicostatus Bransen and Mehl, 1933. Radiolarians identified in this sample are Cenosphaera hexagonalis Aberdeen, 1940, abundant Oriundogutta (?) varispina,
n. sp., rare Pseudospongoprunum (?) tauversi and Pa- laeoactinosphaera (?) octaspina ?.
Conodont sample 3 occurs several meters above the top of Zone 6 and is interpreted as Pridolian based on the presence of Dapsilodus obliquicostatus and a species of Belodella possessing a “fan” which is formed by denticles on the side of the cusp.
COMPARISON WITH OTHER SILURIAN RADIOLARIAN FAUNAS
Several detailed works describe Silurian radiolarians from Kazakhstan, Japan, and the Canadian Archipel- ago. A comparison of each of these faunal assemblages to the Caballos Novaculite assemblages follows and a preliminary correlation appears in Text-figure 7.
SOUTHERN URALS, KAZAKHSTAN
Nazarov (Nazarov, 1975, 1988; Nazarov and Or- miston, 1984) described radiolarians from lower Lud- lovian multicolored shales and cherts along the Sak- mara River that contained Oriundogutta (?) kingi, n. sp. (identified as Jnanihella macroacantha Rist, 1892) and Secuicollacta cassa (Nazarov and Ormiston, 1984). Both S. cassa and Oriundogutta (?) kingi occur within the Rotasphaera Superzone of the Marathon uplift. The Urals material is not extensively figured and only a preliminary comparison can be made (Text-figure 7). Chronostratigraphic assignment of this section to the Ludlovian is based on the graptolites Monograptus marri Perner, Peltalograptus tenuis (Barrande), and Streptograptus sp. indet. which were identified by T. N. Korenj (Nazarov, 1975).
CORNWALLIS ISLAND, CANADIAN ARCHIPELAGO
Radiolarians have been recovered from micritic graptolite-bearing limestones of Llandoverian—Wen- lockian age (Holdsworth, 1977; Goodbody, 1986, 1988; Renz, 1990). Accurate age control is based on grap- tolites and conodonts. Multiple samples from mea- sured sections have been recovered and show an ex- ceptionally well-preserved fauna rich in rotasphaerids, undescribed Palaeoactinommids, and delicate spicular Palaeosceniidids. In addition to the rotasphaerids, the Cornwallis Island material have Cenosphaera hexa- gonalis Aberdeen, 1940, and Goodbodium Furutani, 1990 in common with the Marathon uplift material. No forms resembling Praespongocoelia n. gen. or Bi- pylospongia n. gen. have been recovered from Corn- wallis Island. Their absence may be explained: 1) by a possible older age for the Cornwallis Island material, or 2) by paleoecologically controlled distribution of the robust spongy taxa. Estimates of paleogeographic re- constructions place Cornwallis Island approximately 30 degrees north of the Marathon uplift (Scotese and
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 15
Furutani, 1990, Japan
This Paper
D. unicus - P. (?) tauversi
Rotasphaeracea - D. unicus
Se egeye ee
“J Praespongocoelia - SS ee S. (?) magnaspina Z.yoshikiensis RS
Praespongocoelia
Fusulfanus P. asymmetrica osobudaniensis
Rotasphaerid Superzone (Ro)
Wakamatsu et al, 1990, Japan
\ So : N
S.parvus- 3 S. kamitakarensis NN SS
S:? exquisita
Nazarov, 1988, Kazakhstan
LATE SILURIAN
|. tarangulica- S. cassa
EARLY SILURIAN
Llandovery
Text-figure 7. —Correlation of local radiolarian zones in the Marathon uplift with radiolarian assemblages described from Japan and
Kazakhstan.
McKerrow, 1990), so both possibilities are equally likely.
JAPAN
By far, the most extensive work on Silurian radio- larians appears in studies by Wakamatsu et al. (1990) and Furutani (1990) from two regions in Japan. Ra- diolarians have been recovered from measured sec- tions of partially dismembered siliceous and tuffaceous shale sequences from the Kurosegawa Tectonic Zone (Wakamatsu et al., 1990) in southwestern Japan, and from the Fukuji Area, Gifu Prefecture, central Japan (Furutani, 1990). Local radiolarian assemblages were described for each region and are discussed below.
Kurosegawa Tectonic Zone
Four distinct assemblages described by Wakamatsu et al. (1990) are interpreted to be of Silurian age. Struc- tural dismemberment of the Kurosegawa sections and poor chronostratigraphic control have made the strati- graphic relationships between assemblages difficult to interpret. The Devoniglansus unicus assemblage has been interpreted to be younger than the Pseudospon- goprunum sagittatum assemblage (Wakamatsu et al., 1990), yet comparison with the stratigraphically intact
assemblages of the Marathon uplift indicates that the P. sagittatum assemblage may be younger than D. un- icus assemblage (Text-figure 7). A description of the four assemblages and correlation to the Marathon bio- zones follows.
Assemblage 1. Secuicollacta ? exquisita Assem- blage.—This assemblage is poorly preserved and only a few taxa are described, none of which are particularly diagnostic. It contains Secuicollacta exquisita Waka- matsu et al., 1990, a poorly preserved rotasphaerid with 10 or more rod-shaped primary spines and rem- nants of secondary spines, and a specimen of Good- bodium. Based on the presence of Secuicollacta, this assemblage occurs within the Rotasphaerid Superzone. The absence of inaniguttids, such as Zadrappolus spp., and Praespongocoelia spp. suggests that it may possibly be equivalent to Zone | of the Marathon uplift or older. Whereas absences of taxa are not always reliable as a means for biostratigraphic correlation, the Zadrap- polus spp. and Praespongocoelia spp. are robust taxa that survive in poorly preserved samples at least as well as the rotasphaerids. It is doubtful that their ab- sence would be controlled by preservational bias. Fur- thermore, these Zadrappolus and Praespongocoelia are not unknown from the Kurosegawa tectonic zone. Wa-
16 BULLETIN 345
kamatsu et a/. (1990) reports them from other samples in the area, making a strong case for this sample to be correlative to Marathon uplift Zone | or older. Assem- blage 1 comes from the G2 Formation which is re- ported as being of late Llandoverian to Wenlockian age, based on trilobites and conodonts.
Assemblage 2. Pseudospongoprunum tazukawaen- sis Assemblage. —This assemblage contains rotas- phaerids and Pseudospongoprunum tazukawaensis Wakamatsu et a/., 1990 which may be conspecific with Praespongocoelia parva Furutani, 1990 (see systematic description). At present, this assemblage is tentatively correlated to the middle part of the Marathon uplift Zone 2, the Praespongocoelia Zone, and is limited to those horizons containing P. parva. The age of this assemblage is reported as middle Wenlockian—middle Ludlovian, based on corals, conodonts, and trilobites.
Assemblage 3. Pseudospongoprunum sagittatum Assemblage.—This assemblage contains Pseudospon- goprunum sagittatum Wakamatsu et al., 1990 and a variety of non-rotasphaerid Spumellariina. Pseudo- Spongoprunum sagittatum is similar to Pseudospongo- prunum (?) tauversi, n. sp. and the presence of the non- rotasphaerid Spumellarians in the P. sagittatum assemblage is consistent with the interpretation that they are the same assemblage. (See the species descrip- tion of P. (?) tauversi for a detailed comparison of the two taxa.) There is no age control for this assemblage other than that stratigraphically, it falls between Upper Silurian and Middle Devonian strata. If this assem- blage is equivalent to the P. (?) tauwversi Zone, then the age can be determined as Late Silurian based on the conodont control in Marathon uplift.
Assemblage 4. Devoniglansus unicus Assem- blage.—This assemblage is low in diversity and con- tains Devoniglansus unicus as well as Helioentactinia ? prismspinosa Wakamatsu et al., 1990. First-hand ex- amination of type material from this assemblage shows it to be equivalent to the D. unicus Assemblage in the Marathon uplift. Helioentactinia ? prismspinosa has the same cortical wall structure as /nanigutta and be- cause the authors could not discern an internal spicule within the medullary shell, they tentatively placed it in the genus Helioentactinia Nazarov, 1975. This spe- cies also co-occurs in the D. unicus assemblage in the Marathon uplift. There is no age control for this as- semblage in Japan, yet the authors have presumed it to be Early Devonian based on its dissimilarity with other described Silurian faunas. Conodonts indicate the age of D. unicus is no younger than Pridolian (Late Silurian) in Zone 6 of the Marathon uplift.
Fukuji Area, Gifu Prefecture
Four radiolarian assemblages are described from tuffaceous shales exposed in the Ichinotani and Oso-
budani Valleys (Furutani, 1990). Age control is based solely on comparison to other Silurian radiolarian as- semblages; no independent chronostratigraphic cor- relation exists, although the abundance of tuffaceous material indicates a strong potential for future geo- chronometric calibration.
Fusalfanus osobudaniensis Assemblage.—This as- semblage is defined by the presence of F. osobudan- iensis Furutani, 1990 and 1s characterized by abundant Fusalfanus, Rotasphaera (Secuicollacta), Goodboa- ium, and Entactinosphaera. Fusulfanus osobudanien- sis is found both in Zone | and the lower part of Zone 2 of the Marathen uplift. In Zone 2, it is found in co- occurrence with Praespongocoelia fusiforma, n. sp., whereas in the Fukuji Area, the ranges of F. osobu- daniensis and Praespongocoelia do not overlap. It is therefore presumed that the lower part of Zone 2 is either not present or was not sampled in the Fukuji Area and that the F. osobudaniensis assemblage is cor- relative only to Zone | in the Marathon uplift.
Praespongocoelia (Spongocoelia) parva—Praespon- gocoelia (Spongocoelia) kamitakarensis Assem- blage.—This assemblage is characterized by the pres- ence of Praespongocoelia parva Furutani, 1990 and P. kamitakarensis Furutani, 1990 Rotasphaera spp., and Zadrappolus spinosus Furutani, 1990. All but P. kam- itakarensis are identified in Zone 2, the Praespongo- coelia Zone of the Marathon uplift. This assemblage is considered equivalent to the upper part of Zone 2. The lower part of Zone 2 contains P. fusiforma and F. osobudaniensis, neither of which were reported from this zone.
Zadrappolus yoshikiensis Assemblage.—This as- semblage is characterized by Zadrappolus yoshikiensis Furutani, 1990, Z. tenuis Furutani, 1990, Futobari sol- idus Furutani, 1990, and F. morishitai Furutani, 1990, but these taxa also are shown to occur in Stylosphaera ? sp. A-Stylosphaera ? sp. B assemblage. Taxa belong- ing to Rotasphaera is also reported from this assem- blage. Zadrappolus yoshikiensis and Z. tenuis make their first appearance in the upper part of Zone 3 in the Marathon uplift, but are not considered diagnostic because they range through Zone 4 and into Zone 5. The Z. yoshikiensis assemblage may be be correlative to the upper part of Marathon uplift Zone 3, yet it may also be correlative to the uppermost part of the Ro- tasphaera Superzone above Zone 4. At present, there are insufficient data to demonstrate whether the Z. yvoshikiensis assemblage is stratigraphically below the Stylosphaera ? sp. A—Stvlosphaera ? sp. B assemblage.
Stylosphaera ? sp. A—Stylosphaera ? sp. B Assem- blage.—This assemblage is characterized by the dis- tinct Stylosphaera ? sp. B Furutani, 1990 which pos- sesses bladed to grooved robust, bipolar spines, and by the thinner-spined Stylosphaera ? sp. A Furutani,
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 17
1990. Species of Zadrappolus and Futobari character- istic of the Z. yoshikiensis assemblage are also reported. This assemblage is considered equivalent to Zone 4 of the Marathon uplift. Stv/osphaera ? sp. B is synony- mous with S. (?) magnaspina, n. sp., characteristic of Zone 4, and Zadrappolus spp. are also common in Zone 4. Rotasphaerids occur in Zone 4, yet are not reported in this assemblage. Zone 4 rotasphaerids are rare, small, and were initially overlooked in the Mar- athon uplift material. It is possible that they also may be present in the Fukuji area material in minute num- bers. Furutani interprets this assemblage to be younger than the Z. yoshikiensis assemblage because the spine morphology of Stylosphaera ? sp. A and B resembles that of younger Middle and Late Devonian faunas, however, no stratigraphic evidence supports or refutes this interpretation. It is equally likely that this assem- blage may occur below the Z. voshikiensis assemblage because Z. yoshikiensis taxa occur both above and be- low S. (?) magnaspina in the Marathon uplift. The age of this assemblage was presumed to be Devonian, based solely on the presence of radiolarians with bladed spines, because Middle and Late Devonian radiolarian assem- blages contain abundant forms with bladed spines. Correlation of this zone to Zone 4 of the Marathon uplift suggests its age is no younger than Late Silurian.
Stylosphaera ? sp. C Assemblage. — Stylosphaera? sp. C Furutani, 1990 is the only species reported from this assemblage. It bears strong resemblance to Sty/os- phaera ? sp. B, and may be more or less equivalent. Both Stylosphaera ? sp. B and C appear to have robust grooved spines and fall within the intraspecific varia- tion observed in S. (?) magnaspina, n. sp. Fusalfanus, Zadrappolus, and Cenosphaera hexagonalis Aberdeen, 1940 are also reported from this assemblage, indicating that it is probably close in age to the Stvlosphaera ? sp. B assemblage.
SYSTEMATIC PALEONTOLOGY INTRODUCTION Radiolarian Species Concept
The species concept varies greatly among radiolarian specialists, the largest differences existing between pa- leontologists and neontologists. Living species of ra- diolarians reproduce sexually and their classification follows the biological species concept where genotypic variation between non-interbreeding populations is considered the fundamental criteria for distinguishing between species. Studies of living radiolarians involve the integration of reproductive biology with the study of comparative physiology, ecology, and molecular bi- ology (e.g., Holland and Enjumet, 1960; Petrushev- skaya, 1971). These studies show that the phenotypic expression of the skeleton does not necessarily reflect
genotypic distinction at the species level. Critical dis- cussions by Shaw (1969) and Riedel (1978) of the ap- plicability of the species concept to paleontology point out the subjectivity involved in binomial classification. By necessity, fossil taxa are classified entirely on the basis of skeletal morphology, thereby making their re- lationship to biologic species at best speculative.
The term morphospecies has been used by some (e.g., Pessagno et a/., 1984; Blome, 1984) to serve as a reminder that identifying fossil groups on the basis of skeletal morphology is distinct from considering them as species in a biologic sense. Morphospecies are, in essence, a collection of shapes which are interpreted to have some other relationship such as a phylogenetic, biostratigraphic, or ecologic relationship. The rela- tionship reflected in the taxonomic scheme is generally the one of greatest interest or importance to its author. For example, a classification scheme designed for bio- stratigraphic utility might be considered artificial from a phylogenetic standpoint. It may not be the most ap- propriate manner of classification to show phylogenetic relationships and should not be expected to.
In the case of Paleozoic radiolarians, little is known about their phylogenetic relationships or ecologic con- straints. Biostratigraphically, Paleozoic radiolarians are shown to be extremely useful. Consequently, the prin- cipal goal in erecting this taxonomic framework is to describe a number of characteristic radiolarian mor- phospecies shown to have biostratigraphic utility. The characters that distinguish taxa, however, follow Rie- del’s philosophy of being characters purported to have phylogenetic significance, and may help in establishing phylogenetic relationships. The following criteria have been used as a general guideline for subdividing taxa at the various hierarchical levels: Family level: internal structure, such as the presence of a medullary shell or an internal spicule; Genus level: mode of cortical and medullary wall construction, spine distribution; Spe- cies level: degree of sphericity, development of pore network, pore shape, spine shape, spine size, and num- ber of spines. These criteria are consistent with those used by other Paleozoic workers (Nazarov, 1988; Cheng, 1986; Furutani, 1990) who interpret them to reflect phylogenetic relationships better than a classi- fication based solely on shell symmetry and geometry.
The morphologic characters used to identify radio- larian morphospecies herein are those that are easily identifiable, insuring that the taxonomic scheme can be used by others. The criteria chosen are those that are easily recognizable using standard micropaleon- tological techniques of reflected light and scanning electron microscopy. All taxa described are common (greater than 5% of the specimens in at least | sample). Distinct taxa that are not found in sufficient abundance (less than 5 specimens) to study adequately are figured
18 BULLETIN 345
primary spine
primary spine unit TR
secondary rod
secondary spine , primary rod
Text-figure 8.—Schematic diagram showing skeletal elements of the Rotasphaeridae.
but not formally described. Characteristics that are dif- ficult to recognize (e.g., internal skeletal characteris- tics), or are fragile and not always preserved, are avoid- ed so taxa can be consistently identified. Differential preservation can alter the appearance of specimens by removing certain features, such as delicate spines. A wider latitude of variation in secondary spines is al- lowed in many of the morphospecies than might nor- mally be considered when working with material which is consistently well-preserved.
All holotypes are assigned U.S. National Museum specimen numbers (labeled USNM), and will be stored there for reference. Paratypes will be stored at the Tex- as Memorial Museum at the University of Texas at Austin (labeled TMM). A formal diagnosis appears for all new taxa and for all amended taxa. An informal description is provided for previously described taxa.
Morphological Terminology
A number of new groups of radiolarians are intro- duced herein and require the erection of new termi- nology to describe them. The terminology describing Rotasphaeracea n. superfam. follows that introduced by Holdsworth (1977) to describe the ‘rotasphaerids,’ and that used by Furutani (1990) to describe species of Secuicollacta Nazarov and Ormiston, 1984. The skeletal elements for Rotasphaeracea are illustrated in Text-figures 8 and 9. The following new terms are in- troduced:
1. “Primary spine unit” refers to a single primary spine and the primary rods emanating from its base in a spoke-like fashion (Text-figure 8). Furutani (1990, p. 49) refers to this feature as a “spine unit consisting of a main spine and some bars radiating from the base of the spine.”
2. “‘Primary rod” refers to the rods emanating from the base of the primary spines (Text-Figures 8, 9) and is equivalent to the feature Furutani (1990, p. 49) refers to as a “bar.” Furutani’s use of the term “‘bar”’ is not adopted herein because the term “‘primary bar’ has a separate meaning in spumellarian terminology and re- fers to the extension of the primary spine inside of the cortical shell.
primary spine
secondary rod primary rod
secondary bar
primary bar
medullary structure
Text-figure 9.—Schematic diagram showing skeletal elements of the Pseudorotasphaeridae.
3. “Secondary rod” (Text-figures 8, 9) refers to the shorter rods that are not part of the primary spine unit but instead connect the primary rods together to help form the cortical meshwork.
4. “‘Tenting” is defined as the degree that the pri- mary rods deviate from a plane perpendicular to the primary spine. When the primary rods diverging from the primary spine all lie in a plane, the spine base is not considered tented. If the primary rods diverge out of the plane in a conical fashion, much like the legs of a tripod, the spine base is considered to be tented.
The following new terms are introduced to describe features observed in Pseudospongoprunum Wakamat- su et al. and in Palaeoactinosphaeridae n. fam.:
1. “Collar pores” refer to the pores that encircle a primary spine on the cortical shell.
2. “Collar grooves” refer to grooves that run lon- gitudinally up a primary spine, starting from a collar pore at the base.
RELATIONSHIP BETWEEN THE ROTASPHAERIDAE AND PSEUDOROTASPHAERIDAE
This paper introduces several widely distributed yet previously undescribed families of Spumellariina. Two of the more important groups considered are the Ro- tasphaeridae and the Pseudorotasphaeridae. These two families share a distinct cortical shell morphology, the rotasphaerid structure (Text-figure 8), and are consid- ered to be one of the more characteristic components of Late Ordovician and Silurian radiolarian assem- blages. All Spumellariina that exhibit the rotasphaerid structure are grouped into the superfamily Rotasphaer- acea. The first Rotasphaeracea described (Holdsworth, 1977) lack any type of internal structure, which has lead me to interpret the mode of shell construction as arising from the coalescence of rays emerging from multiple primary spine centers (Text-figure 8). Rotas- phaeracea lacking internal structures are classified in the family Rotasphaeridae. It has become apparent
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 19
through the examination of some broken specimens, however, that some forms exhibiting the rotasphaerid structure also have an internal structure. From the out- side, some of these forms easily pass for rotasphaerids. In addition to the rotasphaerid structure, the number and placement of spines, development of the cortical meshwork, and development of secondary spines all are similar to that of the rotasphaerids. All taxa with an internal structure and the rotasphaerid structure on the cortical shell are placed into the family Pseudo- rotasphaeridae.
Preservational problems prevent the nature of the Pseudorotasphaeridae internal structure from being fully described at this time. In those specimens in which the structure can be seen, it appears to vary from a doubled shell to a loose inner framework connected to the cortical shell by thin bars that join at the base of the primary spines and at other points on the cortical shell (Text-figure 9). A broken specimen showing the internal structure was examined with scanning electron microscopy (PI. 4, figs. 1, 2) and revealed that primary bars connecting the internal structure to the primary spine appear to be hollow tubes, whereas the secondary bars connecting to the cortical shell appear to be thin- ner solid rods. Future study of material with better preserved internal structures may further clarify the relationship between the Pseudorotasphaeridae and the Rotasphaeridae.
Class ACTINOPODA Calkins, 1909 Subclass RADIOLARIA Miller, 1858 Order POLYCYSTIDA Ehrenberg, 1838 Suborder SPUMELLARIINA Ehrenberg, 1838 ROTASPHAERACEA, new superfamily
Diagnosis.—Test composed of a single cortical shell or one cortical and one medullary shell. Cortical shell possesses a rotasphaerid structure, consisting of four or more rods emanating from the base of each primary spine in a spoke-like fashion. Rods from different spine centers coalesce to form the principal meshwork of the cortical shell.
Remarks.—This superfamily is composed of two families, the Rotasphaeridae and the Pseudorotas- phaeridae, both of which possess the rotasphaerid structure on the cortical shell, but differ fundamentally in that the Rotasphaeridae lack a medullary shell. The pseudorotasphaerids possess an irregularly shaped medullary shell and commonly have a thicker cortical shell, due to the advanced development of secondary spines (Pl. 4, figs. 3, 4). Many of the Pseudorotas- phaeridae bear strong resemblance to the Rotasphaer- idae, with exception of the internal structure. Based on this strong external resemblance, they are linked at the superfamily level.
Range and occurrence.—Late Ordovician through Late Silurian, reported from west Texas, the Canadian Archipelago, Kazakhstan, and Japan.
ROTASPHAERIDAE, new family
Type genus. — Rotasphaera, new genus Diagnosis.—Test composed of a single cortical shell formed by the coalescence of six or more primary spine units. Each unit consists of a primary spine more or less perpendicular to five or more straight rods (com- monly six) which radiate from its base in a spoke-like fashion. The rods coalesce from the individual spine units to form a coarse latticed network of large polyg- onal pore frames. Pore framework is further subdivid- ed by the development of secondary rods that connect the primary rods together (Text-figure 8). Remarks.—This group was first described by Hold- sworth (1977) as the informal group ““Rotasphaerids.” The distinct radiating structure of the primary spine units is what Holdsworth referred to as the rotasphaer- id structure. Included in the Rotasphaeridae is Rotas- phaera n. gen. and the genus Secuicollacta Nazarov and Ormiston, 1984 emended herein. These two gen- era differ in the number of primary spines and the degree of development of secondary spines. Secuicol- lacta Nazarov and Ormiston (1984) was originally clas- sified under the Haplentactiniidae Nazarov (1980) be- cause it was interpreted to have an internal spicule and weakly developed cortical shell; two characteristics di- agnostic of the Haplentactiniidae. After examining photographs of the type species, Secuicollacta cassa, | interpret the feature referred to as an ectopically placed spicule to be a rotasphaerid structure, and one of sev- eral primary spine units. Secuicollacta cassa is there- fore, formally reclassified under Rotasphaeridae. Range and occurrence.— Members of the family Ro- tasphaeridae are interpreted to be the most primitive of the Rotasphaeracea. The oldest reported occurrence is from the Late Ordovician (Renz, 1990). These Ro- tasphaeridae possess a single, loosely latticed cortical shell with six or more rod-shaped primary spines and poor secondary bar development. The youngest re- ported occurrence of Rotasphaeridae comes from the Late Silurian of the Marathon uplift, west Texas.
Genus ROTASPHAERA, new genus
Type species.— Rotasphaera marathonensis, new species
Diagnosis.—Shell may be round to polygonal in out- line with six to nine primary spines which are mor- phologically distinct from the secondary spines. Pri- mary spines are commonly blunt-ended or tapered, may exhibit blades or grooves at the proximal end, and are circular in cross section at the distal end. Secondary
20 BULLETIN 345
Table 2.—Measurements (in um) of Rotasphaera beckwithensis. Numbers of specimens measured are in parentheses.
mini- Maxi- mean mum mum
cortical shell diameter 106 84 140 (11) avg. length primary spine 55 37 65 (11) avg. length secondary spine 6 5 9 (7) width primary spine base 20 16 26 (11) width secondary spine base 3155) 3 “ (5S) diameter primary spine unit 51 37 65 (11)
spines are commonly thin nontapered rods or nodes which range from 5 to 50% of the primary spine length.
Remarks.—Rotasphaera is distinguished from Se- cuicollacta Nazarov and Ormiston, 1984, emended herein, by having fewer primary spines and more dif- ferentiation between primary and secondary spine morphology. Many Rotasphaera have seven primary spines which give the shell a hexacubic appearance. Specimens can commonly be oriented so that two of these spines are positioned at opposite poles, and the remaining five occur equatorially. Pore development is also variable. Hexastylus basiporosus (Aberdeen, 1940, p. 136, pl. 21, figs. 6, 9, 13) appears to belong to the genus Rotasphaera, yet its identification at the species level is not possible in thin-section and it is treated as nomen dubium.
Taxa within Rotasphaera are distinguished from each other by variations in the following characteristics:
1. Degree of sphericity and tenting. Non-tented taxa tend to have a spherical outline, like Rotasphaera mar- athonensis, n. sp., whereas tented taxa have a polygonal outline, such as Rotasphaera beckwithensis, n. sp.
2. Number, shape, and size of primary spines.
3. Diameter of primary spine units relative to shell diameter.
4. Degree of secondary rod development. Secondary rod development is directly reflected in the develop- ment of the cortical shell pore network. Taxa with poorly developed secondary rods have angular pores of varying shape and size, such as Rotasphaera nuda, n. sp., whereas those with more extensive secondary rod development have a more regularly shaped pore network and often smaller pores, such as with Rotas- phaera robertsorum, n. sp.
5. Shape and size of secondary spines and their de- gree of development. Secondary spines vary from small nodes to thin rods, yet in all cases secondary spines are substantially smaller and thinner than primary spines. Preservation of delicate secondary spines may be in part preservationally controlled. Therefore, less emphasis is placed on secondary spine development than on other features.
Rotasphaera beckwithensis, new species Plate 2, figures 7-12; Plate 8, figure 4, 5
Diagnosis.—Test subcircular with six to seven pri- mary spines. Primary spines are robust and tapered and measure approximately 50% the cortical shell di- ameter. Six to seven wedge-shaped grooves and alter- nating ridges at base and extend up 15 to 30% of the spine length. Six primary rods extend from spine bases with minor tenting. Diameter of primary spine units are 45% of shell diameter. Secondary rod development is moderate resulting in very angular pores. Secondary spines are thin rods, three to four microns in width, and 25% the length of the primary spine.
Comparison.— Rotasphaera beckwithensis can be distinguished from Pseudorotasphaera communa, n. sp. by its fewer, more robust primary spines, and from R. marathonensis, n. sp. by its subcircular outline and shorter, more tapered primary rods. Secondary spines are thin and delicate and are commonly not preserved, leaving a nodose appearance to the cortical shell.
Measurements.—See Table 2.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—Named for the Beckwith Hills, near the type locality.
Designation of types.—Holotype USNM 466291, paratype TMM 1850TX2.
Range and occurrence.—Silurian, Zones 2 and 3 of the Marathon uplift, west Texas.
Rotasphaera delicata, new species Plate 2, figures 17, 18
Diagnosis.—Subcircular shell with six to seven long, slender primary spines. Primary spines are cylindrical and are approximately 70% the length of the cortical shell diameter. Five to six thin primary rods extend from primary spine base with minor tenting. Diameter of primary spine unit is small, comprising about 35% of shell diameter. Thin, poorly developed secondary rods create a delicate open meshwork of irregularly shaped pores. Secondary spines occur as nodes and commonly are not preserved.
Remarks.—This species is distinguished by its del- icate open meshwork and long slender spines.
Measurements.—See Table 3.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) delicatus = delicate.
Designation of types.—Holotype USNM 466292, paratype TMM 1849TX3.
Range and occurrence.—Silurian, Zone 1 through lower Zone 3 of the Marathon uplift, west Texas.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE Ds
Table 3.— Measurements (in um) of Rotasphaera delicata. Num- bers of specimens measured are in parentheses.
Table 4.— Measurements (in um) of Rotasphaera marathonensis. Numbers of specimens measured are in parentheses.
MInl- MaxXIi- mean mum mum
MInI- mMaxt- mean mum mum
cortical shell diameter 104 88 121 (6) avg. length primary spine 70 65 81 (6) avg. length secondary spine 7 5 8 (3) width primary spine base 17 15 19 (6) diameter primary spine unit 40 Si 47 (6)
Rotasphaera marathonensis, new species Plate 2, figures 1-4; Plate 8, figures 1, 2
Rotasphaerid morphotype A Noble, 1993b, p. 278, pl. 1, fig. 1.
Diagnosis.—Test with circular outline possessing six to seven primary spines. Primary spines are cylindrical, tapering towards the distal third, are blunt-ended, and usually measure slightly more than 50% of the shell diameter. Spine base is composed of five to seven rods with little to no tenting. Primary spine unit diameter measures approximately 35% of shell diameter. Sec- ondary rod development is moderate and pores are moderately large. Secondary spines are well developed thin rods that are approximately 30 to 40% the length and width of the primary spines.
Remarks.—Presence of secondary spines appears to be controlled partly by preservation. Paratypes include forms where spines have broken off, resulting in an altered appearance from the holotype.
Comparison.—Rotasphaera marathonensis differs from Rotasphaera robertsorum by having larger pore frames, and from Rotasphaera beckwithensis by having a more circular outline with non-tented primary spine units.
Measurements.—See Table 4.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—This commonly occurring rotasphae- rid is named for the Marathon uplift.
Designation of types.—Holotype USNM 466290, paratype TMM 1849TX2.
Range and occurrence.—Silurian, Zones 2 through 4, Marathon uplift, west Texas.
Rotasphaera nuda, new species Plate 1, figures 17, 18
Diagnosis.—Small, subcircular shell with six to sev- en cylindrical, slightly tapered primary spines approx- imately 50% the cortical shell diameter. Six to seven faint, shallow grooves are sometimes seen at base of primary spines. Commonly six primary rods with mi- nor tenting extend from each spine base to form coarse angular meshwork with poor secondary rod develop- ment. Secondary spines are not developed.
cortical shell diameter 127 112 154 (9) avg. length primary spine 58 49 65 (9) avg. length secondary spine Wa/ 13 19 (9) width primary spine base 19 18 20 (9) width secondary spine base 6 5 u (7) diameter primary spine unit 45 37 51 (9)
Remarks.— Absence of secondary spines may be a function of poor preservation. In species where sec- ondary spines are poorly preserved, such as Rota- sphaera delicata, they leave nodes or remnants at the point where the secondary spine joins the cortical shell. Very minor nodes are seen at some pore junctures in Rotasphaera nuda. These nodes may indicate very del- icate secondary spines that were not preserved, but is presently speculative.
Comparison.—Rotasphaera nuda 1s similar to Ro- tasphaera quadrata n. sp. but is distinguished by hav- ing a more open pore network with poorly developed secondary rods, and having a less quadrate outline. It differs from Rotasphaera delicata n. sp. by having more robust, shorter primary spines, and a less rounded out- line.
Measurements.—See Table 5.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) nudus = bare.
Designation of types.—Holotype USNM 466293, paratype TMM 1850TX3.
Range and occurrence.—Silurian, Zones | through 3 of the Marathon uplift, west Texas.
Rotasphaera quadrata, new species Plate 2, figures 13-16, 19, 20
Diagnosis.—Test quadrate in outline with six to eight long, cylindrical to slightly tapered primary spines. Pri- mary spines are 60 to 80% as long as the shell diameter. Six of the spines occur orthogonally with additional spines added asymmetrically. Six to seven primary rods extend from each primary spine base and are highly tented, contributing to the shell’s quadrate outline.
Table 5.— Measurements (in unm) of Rotasphaera nuda. Numbers of specimens measured are in parentheses.
minti- Maxti- mean mum mum
cortical shell diameter 108 93 130 (7) avg. length primary spine 53 47 65 (7) width primary spine base 15 14 17 (7) diameter primary spine unit 52 42 56 (7)
bo tN
Table 6.— Measurements (in um) of Rotasphaera quadrata. Num- bers of specimens measured are in parentheses.
mini- — maxi-
mean mum mum cortical shell diameter 86 74 112 (8) avg. length primary spine 58 56 70 (8) avg. length secondary spine 9 5 18 (3) width primary spine base 19 14 20 (8) width secondary spine base 3 2 4 (5) diameter primary spine unit 47 37 56 (8)
Tenting in spine bases forms 6 to seven wedge-shaped grooves alternating with the primary rods at base of spine. Grooves may extend as much as 50% of the primary spine length. Secondary rod development is moderate, resulting in polygonal pore frames. Second- ary spines are short thin rods approximately 20% the length of the primary spines and commonly are not preserved.
Comparison.—This species is distinguished from other species of Rotasphaera by its quadrate shell, high degree of tenting, and long straight spines. It is distin- guished from R. delicata by having thicker pore frames and a more quadrate outline.
Measurements.—See Table 6.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.), quadratus = square.
Designation of types.—Holotype USNM 466294, paratypes TMM 1844TX2, TMM 1857TX1.
Range and occurrence.—Late Silurian, Zone 3 of the Marathon uplift, west Texas.
Rotasphaera robertsorum, new species Plate 2, figures 5, 6
Rotasphaerid morphotype A Noble, 1993b, p. 278, pl. 1, fig. 4.
Diagnosis.—Test circular in outline possessing six to seven blunt-ended primary spines measuring ap- proximately 50% of the shell diameter. Seven to eight primary rods extend from spine bases and are non- tented. Diameter of primary spine units are approxi- mately 30% of shell diameter. Secondary rods are well developed. Secondary spines are thin and rod-shaped and commonly are not preserved.
Remarks.—Well-developed secondary rods in R. robertsorum producing polygonal pore frames that are small and more regularly shaped, relative to of the species of Rotasphaera.
Comparison.—R. robertsorum differs from R. mar- athonensis, n. sp. by having more primary rods per primary spine, better developed secondary rod struc- ture, and smaller pores.
Measurements.—See Table 7.
BULLETIN 345
Table 7.—Measurements (in um) of Rotasphaera robertsorum. Numbers of specimens measured are in parentheses.
mini-— maxi- mean mum mum
cortical shell diameter 110 84 140 (6) avg. length primary spine 52 53 74 (6) avg. length secondary spine 7 5 9 (6) width primary spine base 15 11 19 (6) width secondary spine base 3 2 4 (6) diameter primary spine unit 34 28 37 (6)
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—This species is named in honor of the Roberts family of Marathon Basin for their valuable assistance in geologic investigations in the Marathon uplift for over 50 years.
Designation of types.—Holotype USNM 466295, paratype TMM 18S0TX4.
Range and occurrence.—Silurian, Zones 2 and 3 of the Marathon uplift, west Texas.
Genus SECUICOLLACTA Nazarov and Ormiston, 1984
Type species.—Secuicollacta cassa Nazarov and Or- miston, 1984
Emended diagnosis.—Rotasphaerid composed of a single cortical shell with nine or more, commonly 12, primary spines, slight tenting. Secondary spines may be poorly or moderately developed.
Remarks.—Nazarov and Ormiston (1984) state that Secuicollacta should be classified with ‘*Rotasphaer- ids” of Holdsworth (1977), yet their diagnosis differs substantially from the description of Holdsworth’s “Rotasphaerids.”” Instead, Nazarov and Ormiston (1984) describe Secuicollacta as possessing an ectopi- cally placed spicule consisting of five to seven straight rays with one perpendicular rod-like spine. Secondary development of lattice-work enveloping this spicule is interpreted by these authors as the mode of shell de- velopment. Furutani (1990) describes several new spe- cies of Secuicollacta, notes that his taxa possess mul- tiple primary spine units, and thus believes his taxa confer more with the definition of “‘Rotasphaerids” than with the definition of Secuicollacta. Furutani was uncertain if the type species, Secuicollacta cassa, pos- sessed a single spine unit or multiple primary spine units, however, and made no formal emendation of the diagnosis to match that of the ““Rotasphaerids.** I agree with Nazarov and Ormiston (1984) and Furutani (1990) that Secuicollacta and Holdsworth’s “Rotas- phaerids” are the same. Photos of Secuicollacta cassa are oriented so that one primary spine unit shows prominently (Nazarov and Ormiston 1984, pl. IV, fig.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 23
5: Nazarov 1988, pl. XII, fig. 2; Nazarov and Ormis- ton, in press, pl. 4, fig. 3). Other large spines are visible and they appear to have primary rods emanating from them in a rotasphaerid fashion. I agree with Furutani that the ectopically placed spicule of Secuicollacta is one of a number of primary spine units. Therefore, Secuicollacta should be classified with the Rotasphaer- idae, not the Haplentactiniidae.
Although the type species, Secuicollacta cassa, is a rotasphaerid, the species Secuicollacta amoenitas (Na- zarov, 1988, pl. XVI, fig. 2) is not a rotasphaerid and does not belong in the same genus with Secuicollacta cassa. Secuicollacta amoenitas appears to have an in- ternal structure that fits the original generic description of Secuicollacta, with an ectopically placed internal spicule. It is described from the Tetrentactinia barys- phaera—Ceratoikiscum famenium Zone of Late Fa- mennian (latest Devonian age) and clearly has no re- lationship to the rotasphaerids which make their last appearance in the Late Silurian, 40 Ma earlier. The presence of an eccentric an internal spicule in Secui- collacta amoenitas would justify its classification in the Haplentactiniidae Nazarov, 1980. I am not able to make a formal taxonomic revision of Secuicollacta amoenitas in this paper, however, because I have not examined the actual specimens and cannot adequately describe it from the photographs. Since there is no genus that S. amoenitas fits into, a new genus will need to be erected by someone who has access to material that contains S. amoenitas.
Taxa within Secuicollacta are distinguished from each other by variations in:
1. Number and shape of primary spines. Primary spines may be rod-shaped, like Secuicollacta cassa ?, distally tapered, like Secuicollacta solara, or flattened, like Secuicollacta (?) platyspina.
2. Development of secondary spines and their de- gree of morphological divergence from primary spine morphology.
Range and occurrence.—Silurian, Zones | through 4 of the Marathon uplift, west Texas, Kurosegawa Tec- tonic Zone and Fukuji Area, Japan, southern Urals, Kazakhstan.
Secuicollacta cassa, Nazarov and Ormiston
?Palaeoephippium ? cf. echinatum Nazarov, B.B. 1988, p. 209, pl.
XII, fig. 5.
Emended diagnosis.—Test round in outline with a minimum of ten long, thin, rod-shaped primary spines. Six primary rods emerge from spine bases with minor tenting. Secondary rod development is poor and mesh- work is coarse with large irregularly shaped pores. Sec- ondary spines are weakly developed, short, thin rods.
Remarks.—The original diagnosis of Secuicollactta cassa describes an ectopically placed spicule consisting
Table 8.— Measurements (in um) of Secuicollacta cassa?. Numbers of specimens measured are in parentheses.
MINI- maxi- mean mum mum
cortical shell diameter 141 130 158 (6) avg. length primary spine 58 47 74 (6) width primary spine base 17 14 19 (6)
of five to seven straight rays with one perpendicular rod-like spine. As was discussed in the remarks section under the genus, the feature described as an ectopically placed spicule is interpreted to be one of a number of rotasphaerid primary spine units that was mistaken for an ectopic spicule. Therefore, the emended diagnosis differs substantially from the original but is believed to more accurately describe the actual morphology. A specimen identified as Palaeoephippium ? cf. echina- tum (Nazarov, B.B. 1988, p. 209, pl. XII, fig. 5) is a rotasphaerid that may also be conspecific with S. cassa, but the spines are not sufficiently well preserved to be certain.
Comparison. — Secuicollacta cassa differs from other species of Secuicollacta by its rod-shaped primary spines, and its sparse, thin secondary spines.
Secuicollacta cassa ?, Nazarov and Ormiston, 1984 Plate 1, figures 1, 2
Diagnosis.—Test round in outline with a minimum of 12 long, thin, rod-shaped primary spines. Six pri- mary rods emerge from spine bases with minor tenting. Secondary rod development is poor and meshwork is coarse with large irregularly shaped pores. Secondary spines are sparse nodes.
Remarks.—Specimens of Secuicollacta cassa ? re- covered from the Caballos Novaculite differ slightly from the type specimen of S. cassa by having more poorly developed secondary spines. Unfortunately, only one specimen of S. cassa has been published and it is difficult to determine the latitude of intraspecific vari- ation recognized by the original authors. The lack of secondary spines in the Caballos material is very likely a function of preservation. Secuicollacta cassa ? may be distinguished from other species of Secuicollacta and Rotasphaera by its simple, thin, rod-shaped spines, and poor secondary spine development.
Measurements.—See Table 8.
Range and occurrence.—Silurian, Zones | through 3 of the Marathon uplift, west Texas.
Secuicollacta foliaspinella, new species Plate 1, figures 9-12
Rotasphaerid morphotype B Noble, 1993b, p. 278, pl. 1, fig. 2.
Diagnosis.—Shell circular in outline with 10 or more thin, slightly tapered, blunt-ended primary spines,
24 BULLETIN 345
Table 9.—Measurements (in um) of Secuicollacta foliaspinella. Numbers of specimens measured are in parentheses.
Table 11.—Measurements (in um) of Secuicollacta solara. Num- bers of specimens measured are in parentheses.
mini- — maxi- mean mum mum
mini- — maxi- mean mum mum
cortical shell diameter 143 NAIL 158 (7) avg. length primary spine 53 47 65 (6) avg. length secondary spine 35 28 37 (5) width primary spine base 19 18 20 (7) width secondary spine base 12 9 i7/ (7)
commonly with six primary rods. Primary spines are short, measuring between 30 to 40% of shell diameter, and are not substantially larger than the secondary spines. Spine bases are non-tented. Secondary rod de- velopment is moderate and pores are rounded but ir- regularly shaped. Pore size is highly variable. Some secondary spines are connected in a flange-like fashion. Secondary spines are well developed, blades approxi- mately 60% the length and width of the primary spines.
Comparison.—Secuicollacta foliaspinella is similar to S. itoigawai Furutani, 1990 in that they are both large with well developed primary and secondary spines, and that they are circular to subcircular in outline. They differ in that S. foliaspinella has distinct flanges connecting primary and secondary spines, and primary spines are shorter, blunt-ended and slightly tapered. Primary spines on S. itoigawai are longer, non-tapered, and morphologically more similar to S. cassa.
Measurements.—See Table 9.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) folium = leaf, spinellus = little spine.
Designation of types.—Holotype USNM 466286, paratypes TMM 1850TX1, TMM 1854TX1.
Range and occurrence.—Silurian, Zones 2 and 3 of the Marathon uplift, west Texas.
Secuicollacta (?) platyspina, new species Plate 1, figure 16
Diagnosis.— Large shell with spiked appearance due to 12 or more bladed knife-like primary spines. S1x to seven thick primary rods radiate from each spine base and form several bladed ridges. Secondary spines of
Table 10.—Measurements (in um) of Secuicollacta (?) platyspina. Numbers of specimens measured are in parentheses.
mini--— maxi- mean mum mum
cortical shell diameter 143 130 158 (5)
avg. length primary spine 63 56 67 (5S) avg. length secondary spine 54 47 60 (5) width primary spine base 28 24 35 (5) width secondary spine base 21 19 26 (5)
cortical shell diameter 127 112 140 (8) avg. length primary spine 63 51 74 (8) avg. length secondary spine 41 28 56 (8) width primary spine base 20 18 23 (8) width secondary spine base 13 9 N7/ (8)
similar appearance, yet are smaller (80 to 90% of pri- mary spine length). Bladed secondary spines obscure the pore network, yet pores seem to be angular. Pore diameter is approximately equal to pore frame thick- ness.
Comparison. — Secuicollacta (?) platyspina bears re- semblance to and is most likely a descendant of S. solara,n. sp. It differs from Secuicollacta solara in that all spines are flattened blades, whereas the spines of S. solara are blunt-ended, slightly tapered rods.
Measurements.—See Table 10.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(Gr.) platys = flat, (L.) spina = spine.
Designation of types.—Holotype USNM 466287, paratype TMM 1844TX1.
Range and occurrence.—Late Silurian, Zone 3 of the Marathon uplift, west Texas.
Secuicollacta solara, new species Plate 1, figures 3-8; Plate 8, figures 3, 6
Secuicollacta sp. cf. S. horrida Furutani, 1990, p. 51, pl. 11, figs. 6, 7:
Description.—Test polygonal in outline with 10 to 15 tapered primary spines. Six to seven primary rods with moderate tenting radiate from spine bases. Mesh- work is open and pores are large, irregularly shaped polygons. Secondary spines are well developed and vary in size from 30 to 50% of primary spine size.
Remarks.—Some of the larger secondary spines have the appearance of a small primary spine with four pri- mary rods. It is believed that these are secondary spines emerging at a four-way juncture, yet they may possibly be earlier growth stages of primary spines.
Comparison.—Secuicollacta solara is distinguished from Secuicollacta horrida by having slightly thicker, shorter, and more tapered primary spines, and by hav- ing more numerous secondary spines.
Measurements.—See Table 11.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) solaris = sun.
Designation of types.—Holotype USNM 466289, paratype TMM 1849TX1.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE
Range and occurrence.—Silurian, Zones | through 3 of the Marathon uplift, west Texas, Fusalfanus oso- budaniensis Zone of Fukuji Area, Gifu Prefecture, Ja- pan.
Secuicollacta sp. A Plate 1, figure 15
Diagnosis.—Shell polygonal in outline with 10 or more primary spines. Six thick primary rods extend from each spine base with moderate tenting. Secondary rod formation is poor and pore network is coarse and highly angular. Secondary spines are sparse and stubby.
Remarks.—This species exhibits prominent primary rods which appear to have overlapping relief with in- tersecting rods, much like the relief between overlap- ping strands of a ball of twine.
Comparison.—It can be distinguished from S. solara by its prominent primary rods and by its highly angular pores. This species is not formally described because of lack of an adequate number specimens.
Range and occurrence.—Silurian, Zone | of the Mar- athon uplift, west Texas.
Family PPEUDOROTASPHAERIDAE, new family
Type genus.— Pseudorotasphaera, new genus
Diagnosis.— Cortical shell of angular meshwork con- nected to loosely latticed medullary shell. Six to seven robust and commonly grooved primary spines. Five to six rods radiate from the base of each primary spine, as in the Rotasphaeridae, and diffuse into the pore network. The medullary shell is attached to the cortical shell by primary bars extending from the primary spines and by secondary bars extending from other points on the shell cortical shell (Pl. 4, figs. 1 and 2). Spines are heavily grooved at the proximal end and spine bases are tented, commonly giving shells a polygonal outline. Cortical shell may develop secondary spines giving it a three-dimensional, thickened appearance.
Remarks.—The Pseudorotasphaeridae have an ex- ternal appearance which is similar to the Rotasphaer- idae. Primary spines have a rotasphaerid structure with five or six rods emanating from each primary spine base and serving as the framework for the cortical shell. In some cases, resemblance to the Rotasphaeridae is so strong that a positive distinction can only be made by inspection of the internal structure. The thickened, dense cortical shell of many Pseudorotasphaeridae make internal inspection difficult. The internal struc- tures were observed in broken specimes (PI. 8, figs. 10 and 11) and unbroken specimens with relatively thin cortical shells, like Pseudorotasphaera communa (P1. 8, figs. 8, 9, and 12). It is presently unclear whether the rotasphaerid structure is formed in the same man- ner in both the true Rotasphaeridae and the Pseudo- rotasphaeridae.
N wn
Comparison.—In addition to having a medullary shell, the Pseudorotasphaeridae differ from the Rotas- phaeridae by having primary spines that are more heavily grooved, and more diffuse primary rods. Range and Occurrence.—Silurian, restricted to the Ro- tasphaerid Superzone, in the Marathon uplift, west Texas. Pseudorotasphaera may also occur in Japan. An undescribed specimen from the Fukuji area called Se- cuicollacta sp. B (Furutani, 1990, pl. 13, fig. 8) has robust, grooved spines and may be a pseudorotas- phaerid.
Genus PSEUDOROTASPHAERA, new genus
Type species.—Pseudorotasphaera hispida Noble, new species
Diagnosis.—Latticed cortical shell polygonal to sub- circular in outline with six to seven robust, grooved primary spines. Pore frames are angular to subcircular. Each spine base possesses five to six rods which are continuous with the spine ridges. A loosely latticed medullary shell attaches to the cortical shell by primary bars which extend to each primary spine, and by thin secondary bars connecting to other points on the cor- tical shell.
Remarks.—Species of Pseudorotasphaera may be distinguished by differences in cortical shell sphericity, the shape, length and thickness of the primary spines, size of spine base relative to size of the cortical shell, and the shape, thickness, and abundance of secondary spines. Some species appear with a query (?) because although they possess the external characteristics of Pseudorotasphaera, the internal structure could not be verified.
Range and occurrence.—Silurian, Rotasphaerid Su- perzone of the Marathon uplift, west Texas and pos- sibly Japan (see range and occurrence of family).
Pseudorotasphaera hispida, new species Plate 3, figures 5—7; Plate 4, figures 3, 4
Diagnosis.—Test subcircular in outline with six to seven primary spines. Cortical shell is thickened so that pore-frames are ridge-like and sub-angular (PI. 4, figs. 3, 4). Primary spines are extremely robust and tapered. Five to six prominent wedge-shaped grooves and alternating ridges run the entire length of the spine. Width of grooves at spine base is commonly one and a half to two times as wide as ridges. Primary spine units encompass approximately 60% of the cortical shell diameter. Pores are subangular, ranging from 6 to 10 microns in diameter. Cortical surface is covered with thin, short secondary spines which may bifurcate at their termination. Primary bars extend inward from the cortical shell to join an open meshed inner shell.
Remarks.—Specimens may vary in their appear- ance, based on the degree of secondary spine preser-
26 BULLETIN 345
Table 12.—Measurements (in um) of Pseudorotasphaera hispida. Numbers of specimens measured are in parentheses.
Table 14.—Measurements (in um) of Pseudorotasphaera lanceo- /ata. Numbers of specimens measured are in parentheses.
mini-— maxi-
mean mum mum cortical shell diameter 105 93 140 (9) avg. length primary spine 73 56 88 (9) avg. length secondary spine 20 15 30 (8) width primary spine base 33 28 42 (7) diameter primary spine unit 61 56 65 (9)
vation. Subcircular outline is more apparent in spec- imens with poorly preserved secondary spines (PI. 3, fig. 7).
Comparison.—Pseudorotasphaera hispida may be distinguished from P. lanceolata, n. sp. by having shorter primary spines, smaller pores, and from P. (?) robustispina, n. sp. by having a less circular outline.
Measurements.—See Table 12.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) hispidus = hairy, bristly, rough.
Designation of types.—Holotype USNM 466296, paratype TMM 1854TX2.
Range and occurrence.—Silurian, Zones | and 2 of the Marathon uplift, west Texas.
Pseudorotasphaera communa, new species Plate 3, figures 13-18; Plate 8, figures 8, 9, 12
Diagnosis.—Test polygonal in outline with seven primary spines. Spines have five to six grooves and alternating ridges at base which extend 50 to 80% the length of the spine. Ridges which extend into five to six primary rods at base of primary spine diffuse into pore network. Pores are rounded to subangular in out- line, ranging from five to eight microns in diameter. Secondary spines are short nodes. Medullary shell is a coarse, angular latticed polygon, connected to the cor- tical shell by thin primary and secondary bars (PI. 8, figse8s 92):
Comparison. — Pseudorotasphaera communa has an external resemblance to Rotasphaera quadrata, n. sp., but may be distinguished by having primary spines
Table 13.—Measurements (in um) of Pseudorotasphaera com- muna. Numbers of specimens measured are in parentheses.
mini- MaxI- mean mum mum
cortical shell diameter 104 88 140 (15)
avg. length primary spine 76 62 87 (15) avg. length secondary spine 8 5 17 (6) width primary spine base 31 26 42 (15) diameter primary spine unit 58 47 65 (15)
mini- — maxi- mean mum mum
cortical shell diameter 96 88 102 (5S)
avg. length primary spine 99 84 109 (5) width primary spine base 39 37 42 (5) diameter primary spine unit 61 56 65 (5)
that are more strongly grooved, and by having a less quadrate outline.
Measurements.—See Table 13.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) communa = common.
Designation of types.—Holotype USNM 466297, paratype TMM 1844TX3.
Range and occurrence.—Silurian, Zones | through 3 of the Marathon uplift, west Texas.
Pseudorotasphaera lanceolata, new species Plate 3, figures 8-10; Plate 8, figure 7
Diagnosis.—Test polygonal in outline with six to seven robust primary spines. Primary spines have five pronounced grooves that alternate with five bladed ridges and extend the entire length of the spine. Width of grooves at spine base is two to three times width of alternating ridges. Primary spine units cover 60% or more of cortical shell and are approximately as long as the cortical shell diameter. Pore frames are thick- ened and pores are large, ranging 10 to 18 microns in diameter. Only two or three pores occur in between primary spine units. Secondary spines are thin rods that are rarely preserved.
Remarks.—This species is distinguished by its long and extremely robust spines and by its large pores. The cortical area in between the spines commonly accom- modates only two or three pores.
Comparison.— Pseudorotasphaera lanceolata is dis- tinguished from Pseudorotasphaera hispida, n. sp. and Pseudorotasphaera communa, n. sp. by possessing lon- ger, more robust spines, a more polygonal outline, and fewer, larger pores.
Measurements.—See Table 14.
Type locality.—Wood Hollow, Marathon uplift, west Texas.
Etymology.—(L.) lanceolatus = lance-shaped.
Designation of types.—Holotype USNM 466298, paratype TMM 1840TX2.
Range and occurrence.—Silurian, Zones 1 and 2 of the Marathon uplift, west Texas.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 27
Table 15.—Measurements (in um) of Pseudorotasphaera (?) ro- bustispina. Numbers of specimens measured are in parentheses.
Table 16.—Measurements (in um) of Pseudorotasphaera (?) ro- tunda. Numbers of specimens measured are in parentheses.
mini- — maxti- mean mum mum
mini- MaxXi- mean mum mum
cortical shell diameter 114 102 130 (8) avg. length primary spine 60 56 65 (8) avg. length secondary spine 16 9 19 (5) width primary spine base 28 23 33 (8) width secondary spine base 3 3} 4 (5) diameter primary spine unit 42 35 51 (8)
cortical shell diameter 113 91 134 (9) avg. length primary spine 64 54 77 (9) avg. length secondary spine 17 14 17 (7) width primary spine base 22 21 24 (9) width secondary spine base 5) 5 6 (7) diameter primary spine unit 52 40 67 (9)
Pseudorotasphaera (?) robustispina, new species Plate 3, figures 1-4; Plate 4, figure 5
Rotasphaerid morphotype C Noble, 1993b, p. 278, pl. 1, fig. 3.
Diagnosis.—Test circular in outline with six to seven robust primary spines. Primary spines are blunt-ended and conical with five deep wedge-shaped grooves and alternating ridges extending approximately 90% the length of the spine. Primary spine units are composed of five to six primary rods and are non-tented to slightly tented. Diameter of primary spine units makes up about 35% of shell diameter. Primary rods diffuse into pore structure and pores are subrounded, fairly regular in shape, ranging in size from five to ten microns in di- ameter. Thin rod-shaped secondary spines 25 to 35% the length of primary spines are present. Secondary spines are three to four microns wide and are com- monly not preserved.
Remarks.—This species is tentatively placed in the Pseudorotasphaera because the presence of an internal medullary shell has not been confirmed. Reflected light on several specimens shows the vague outline of a polygonal body inside the cortical shell, yet this may be microcrystalline quartz infilling. Plate 4, figure 5 illustrates the common problem of chalcedony filling in the internal cavity of a specimen and illustrates the difficulties in determining the nature of internal struc- ture.
Comparison.—This species is easily distinguished from Rotasphaera marathonensis, n. sp. and Rota- sphaera robertsorum, n. sp. by its robust grooved spines, and from Pseudorotasphaera hispida, n. sp. by having a rounder outline.
Measurements.—See Table 15.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) robustus = robust, spina = spine.
Designation of types.—Holotype USNM 466299, paratype TMM 1849TX4.
Range and occurrence.—Silurian, Zone 2 of the Mar- athon uplift, west Texas.
Pseudorotasphaera (?) rotunda, new species Plate 3, figures 11, 12
Diagnosis.—Test circular in outline with seven to nine robust primary spines. Primary spines are tapered with five to six shallow wedge-shaped grooves and al- ternating ridges at base that extend 10 to 15% along the spine length. Ridges are round and join with cor- tical shell where they extend as primary rods. Primary rods can be traced the length of one or two pore frames before they diffuse into pore network. Pores are round- ed and irregularly shaped, ranging from three to eight microns diameter. Secondary spines are slender rods that are approximately 25% the length and thickness of the primary spines. Secondary spines are commonly broken, giving cortical shell a nodose appearance.
Comparison. —Pseudorotasphaera (?) rotunda bears a strong resemblance to Rotasphaera robertsorum, 0. sp. due to its round outline and the well developed pore framework in the latter. It is distinguished by having primary spines that are more tapered and prox- imally grooved. This species is questionably assigned to Pseudorotasphaera because no specimens were found which adequately show the internal structure.
Measurements.—See Table 16.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) rotundus = round.
Designation of types.—Holotype USNM 466300, paratype TMM 1843TX1.
Range and occurrence.—Silurian, upper Zone 2 and Zone 3 of the Marathon uplift, west Texas.
Superfamily SPONGODISCACEA Haeckel, emend. Pessagno, 1971
Subsuperfamily PPEUDOAULOPHACILAE Riedel, emend. Pessagno, 1971
Family SPONGURIDAE Haeckel, emend. Pessagno, 1973 Type genus.—Spongurus Haeckel, 1887 Remarks.—This family includes genera with a spongy shell that is ovate or subcircular in shape and consists
28 BULLETIN 345
Table 17.—Measurements (in um) of Pseudospongoprunum (?) tauversi. Numbers of specimens measured are in parentheses.
mini-- maxi- mean mum mum
axial diameter cortical shell 176 158 186 (7) equatorial diameter cortical shell 153 130 aa Gh) length long apical spine 83 74 93 «(7) length short apical spine 60 42 6S @)
of multiple concentric spongy layers. This group is distinguished from the spongy Astroentactiniinae Na- zarov, 1975 (such as Copiellintra Nazarov and Or- miston, 1985 and Copicyntra Nazarov and Ormiston, 1985) because no rays prevail through layers from cen- ter to the outer edge of the cortical shell.
Genus PSPEUDOSPONGOPRUNUM, Wakamatsu ef al., 1990
Type species.—Pseudospongoprunum sagittatum, Wakamatsu et al., 1990
Description.—Subspherical to ovate shell spongy shell with two polar spines. Spongy structure filling the in- side of the shell may show weak concentric layering. Two robust spines of unequal length protrude from each pole occurring at an angle near 180 degrees. A ring of 12 to 15 collar pores appear at base of spines. Shallow grooves, termed collar grooves, originate at base of spine at every third or fourth collar pore and run part way up the spine. Presence of grooves at base of spine creates a slight constriction at its juncture with the body of the shell.
Remarks.—The original description of Pseudospon- goprunum states that the spongy infilling lacks sym- metric structures, yet in the species description of P. sagittatum, the authors note that a faint layered struc- ture is rarely observed in the central part of the shell. Therefore, forms that possess concentric spongy lay- ering are tentatively included herein. Pseudospongo- prunum can be distinguished from the genus Copiel- lintra Nazarov and Ormiston, 1985 by lacking a central latticed sphere and possessing well developed polar spines, and from Spongocoelia Hinde, 1899 and Prae- spongocoelia, n. gen. by lacking an internal cavity. Pseudospongoprunum also bears a strong resemblance to Archaeospongopruninae Pessagno, 1973 but has thicker, more evenly tapered spines that are grooved only at the proximal end.
Pseudospongoprunum (?) tauversi, new species Plate 7, figures 13-15
Diagnosis.—Shell ovate consisting of eight or nine concentric spongy layers. A small hollow appears at center, approximately 20% the diameter of the short
dimension of the shell. Two robust spines emerge from poles at an angle of approximately 175 degrees. The longer of the two spines is slightly shorter than the long axis of the cortical shell. Spines are conical and highly tapered. Collar grooves are pronounced and extend no further than half way up the spine.
Comparison.—This species bears superficial resem- blance to Praespongocoelia parvus Furutani, 1990 but may be distinguished by having a different wall struc- ture and spine morphology. Pseudospongoprunum (?) tauversi has multiple concentric spongy layers and a coarser spongy meshwork (larger pores) than the Prae- spongocoelia spp. The spine length is shorter with re- spect to the length of the spongy cortical shell and spines taper more distally. Pseudospongoprunum (?) tauversi bears strong resemblance to Pseudospongo- prunum sagittatum Wakamatsu et al., 1990, but differs in that the spongy meshwork is slightly looser in Pseu- dospongoprunum sagittatum and the concentric spongy layering is more pronounced in Pseudospongoprunum (?) tauversi.
Measurements.—See Table 17.
Type locality. —Monument Creek, Marathon uplift, west Texas.
Etymology.—This species is named in honor of Dr. Peter Tauvers for his contributions to the geology of the Marathon uplift.
Designation of types.—Holotype USNM 466301, paratype TMM 1858TX1.
Range and occurrence.—Late Silurian, Zone 6 of the Marathon uplift, west Texas, ? Kurosegawa Tectonic Zone, Japan.
Genus DEVONIGLANSUS Wakamatsu et a/., 1990
Type species.— Devoniglansus unicus Wakamatsu et al., 1990
Devoniglansus unicus Wakamatsu et a/., 1990 Plate 7, figures 16-20
Description. —Ellipsoidal shell consisting of multiple concentric spongy layers, an apical spine, and a basal pylome which is surrounded by multiple basal spines.
Remarks.—The genus Devoniglansus Wakamatsu et al. is a good example of why the incorporation of age names into species names can be problematic. This distinctive taxon was originally described from the Yo- kokura-yama area of the Kurosegawa Tectonic Zone, Japan. The authors had no precise age control, but presuming the sample to be Devonian, incorporated the age term into the generic name. Conodonts show that Devoniglansis unicus ranges no higher than Late Silurian age in the Marathon uplift. The last occurrence of D. unicus is below the top of the Devoniglansus unicus—Pseudospongoprunum (?) tauversi Zone, which
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 29
Inanigutta Nazarov & Ormiston 1984
6 spines
1 latticed cortical shell
Futobari Furutani 1990 7 or more spines thick spines 1 irregular latticed cortical shell doubled medullary shell
Inanibigutta Nazarov & Ormiston 1987
6 spines
2 latticed cortical shells
Oriundogutta Nazarov & Ormiston 1987
Inaniguttidae
Nazarov & Ormiston 1984
large spherical shell
cortical: irregularly porous/ latticed medullary: polygonal, latticed rod-shaped spines w/ tapered base
10 - 20 spines 1 thick-walled, porous cortical shell
Inanihella Nazarov & Ormiston 1984
irregularly porous inner cortical shell
‘delicate outer cortical shell may have pylome more than 6 spines
Fusalfanus Furutani 1990, emend. herein
irregularly porous inner cortical shell delicate outer cortical shell
pylome on cortex more than 6 spines doubled medullary shell (?)
Zadrappolus Furutani 1990
20 + spines
1 latticed cortical shell doubled medullary shell spines conical to rod-shaped
Text-figure 10.—Schematic diagram of the genera in the family Inaniguttidae Nazarov and Ormiston, 1984.
is no younger than Pridolian and 1s overlain by several additional meters of Silurian strata. The age of the D. unicus assemblage in the Kurosegawa Tectonic Zone was made from inference and unless independant ge- ochronologic data can demonstrate that D. wnicus rang- es considerably higher in Japan than in the Marathon uplift, it is presumed to be restricted to the Silurian.
Range and occurrence.—Late Silurian, Devoniglan- sus unicus assemblage of Kurosegawa Tectonic Zone, Japan; lower half of Zone 6 of the Marathon uplift, west Texas.
Superfamily INCERTAE SEDIS
Family INANIGUTTIDAE Nazarov and Ormiston, 1984, emended herein
Type genus.—Inanigutta Nazarov and Ormiston, 1984
Emended diagnosis.—Spumellarians with one or more cortical shells that are irregularly porous to lat- ticed, and a latticed subspherical medullary shell. Pri- mary bars extend from primary spines on the cortical shell to the surface of the medullary shell, where they
30 BULLETIN 345
branch into four or more rays that are incorporated into the medullary lattice. Primary spines are generally rod-shaped, but have four to six grooves at the base and are tapered proximally. The grooves occur in be- tween blades which are contiguous with pore frames at the base of the spine.
Remarks.—The Inaniguttidae are a biostratigraph- ically important Silurian group. In the Marathon uplift, they become increasingly abundant up-section and comprise the majority of the assemblages in Zones 4 through 7. The Inaniguttidae are distinguished from the other major group of spherical Spumellariina, En- tactiniidae Riedel (1967), by the absence of an internal spicule, and from the Paleoactinosphaeridae, n. fam. by being larger with rod-shaped spines which are ta- pered and grooved only at the base. The cortical shell is commonly thickened, consisting of a three-dimen- sional network of coarse, irregularly shaped, subround- ed pore-frames which, in some forms, approach a spongy texture with an irregular, three dimensional array of pores (e.g., Fusalfanus osobudaniensis Furu- tani, 1990). Late taxa placed in the Inaniguttidae (e.g., Oriundagutta (?) varispina, n. sp.) exhibit a thick but more organized pore framework where the pores pen- etrate from the inner to the outer side of the cortical shell perpendicular to the shell wall. In earlier forms (e.g., Inanihella sp. A), the pores penetrate from inside to outside of cortical shell in a tortuous pathway not perpendicular to the shell wall. Although the degree of organization of the cortical shell appears to be different between earlier and later forms, all are large taxa pos- sessing a similar subrounded to polygonal latticed medullary shell and similar primary spine morphol- ogy.
In highly spinose forms, the lattice shell appears highly three-dimensional due to the mode of attach- ment of the spine bases to the cortical shell. Spine bases are characteristically grooved and highly tapered. The bars occurring in between the grooves branch out and are contiguous with adjacent pore frames. This gives the pore frames a three-dimensional, spiked appear- ance (e.g., Zadrappolous spinosus Furutani, 1990). Therefore, the sphericity of the cortical shell surface appears largely controlled by the abundance of spines. The taxa included in the Inaniguttidae and a brief de- scription of their characteristics appear in Text-figure 10.
Genus INANIHELLA Nazarov and Ormiston, 1984, emended herein Type species.—Helioentactinia bakanasensis Naza- rov 1980, emend. Nazarov, 1988 Emended diagnosis.—Two attached latticed or ir- regularly porous cortical shells surround a spherical latticed medullary shell. The outer cortical shell is del-
icate. Multiple rod-shaped primary bars emerge from medullary shell and extend past cortical shell to form primary spines. Base of primary spines may be grooved.
Remarks.—The emended diagnosis differs from the original in that it restricts the genus to those taxa pos- sessing two latticed cortical shells. The type species possesses two latticed cortical shells, yet another spe- cies previously classified under this genus, /nanihella macroacantha Rust, emended Nazarov (1988), does not and is provisionally reassigned to the genus Or- iundogutta Nazarov, 1988.
Inanihella sp. A Plate 5, figure 16
Description.— Large irregularly porous cortical shell consisting of two interconnected layers. Outer layer is delicate. Latticed spherical medullary shell. Multiple thin rod-shaped spines (25 or more per hemisphere) extend from cortical shell.
Remarks.—This distinct taxon was found in only one sample and was not in sufficient abundance to describe formally.
Range and occurrence.—Late Silurian, Zone 3 of the Marathon uplift, west Texas.
Genus FUSALFANUS Furutani, 1990, emended herein
Type species.— Fusalfanus osobudaniensis Furutani, 1990
Emended diagnosis.— Coarsely porous inner cortical shell which may possess a pylome. A delicate outer cortical shell is developed outside the coarsely porous, delicate cortical shell, but is rarely preserved. Medul- lary shell is latticed. More than six spines per hemi- sphere on cortical shell. Spines are strongly tapered proximally and may be grooved at proximal end.
Remarks.— Whereas the delicate outer cortical shell is seldom preserved, remnants are commonly seen on the distal ends of the primary spines giving the spines a trident-shaped appearance. No pylomes were found on the Marathon uplift specimens, yet most specimens were damaged or recrystallized on one area of the cor- tical shell, allowing for the possibility that a pylome may have been present but is no longer preserved.
This genus was originally distinguished from /na- nihella Nazarov and Ormiston, 1984, by possessing a spongy inner cortical shell, whereas Jnanihella pos- sesses a coarsely porous cortical shell. The wall struc- ture of the type Fusa/fanus material, however, appears to agree with Jnanihella and is more accurately de- scribed as coarsely porous. Fusalfanus appears to share all of the characteristics of Inanihella except for its medullary shell, which is described as a doubled lattice wall. Photos of the medullary structure of the type specimens are not sufficiently explicit, however, to show
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 31
the doubled wall. Fusalfanus should possibly be treated as a junior synomym for Jnanihella, but further study of the type material of both Fusalfanus and I nanithella is needed before a reclassification can be made.
Fusalfanus osobudaniensis Furutani, 1990 Plate 5, figures 15, 17, 18; Plate 9, figure 1 ?nanihella tarangulica Nazarov and Ormiston, 1984, p. 73, pl. IV,
figs. 3, 4.
Description.—Thick coarsely porous inner cortical shell with traces of a more delicate outer cortical shell and well developed spines. Traces of this outer shell give primary spines a trident-shaped or crown-shaped appearance. A pylome is present on the inner cortical shell. Spines number approximately 15 to 20 on a hemisphere and are grooved at base. Five to six grooves alternate with blades that connect to pore frames at the base of the spine.
Remarks.—Fusalfanus osobudaniensis in the Ca- ballos samples possess the spongy inner cortical shell (Pl. 9, fig. 1), yet no specimens preserving the med- ullary structure were found. Traces of the delicate outer cortical shell are present.
Range and occurrence.—Silurian, Zones | and lower Zone 2 of the Marathon uplift, west Texas; Fusalfanus osobudaniensis Zone of the Fukuji Area, Gifu Prefec- ture, Japan.
Genus ORIUNDOGUTTA Nazarov, 1988
Type species.—Oriundogutta ramificans (Nazarov), 1985
Description.—One porous thick-walled cortical shell surrounds a polygonal to hemispherical medullary shell. Eight to 20 or more spines radiate from cortical shell.
Oriundogutta (?) kingi, new species Plate 6, figures 1, 4 Inanihella macroacantha Rist, 1892, Nazarov, 1988, p. 209, pl. XII, fig. 1.
Inanihella macroacantha ? Riist, 1892, Nazaroy and Ormiston, 1993, p. 34, pl. 2, figs. 6-8.
Diagnosis.—One thick cortical shell with 15 to 20 long robust spines per hemisphere. Spines are highly tapered at proximal end and contain four to five prom- inent grooves alternating with ridges. Spine cross sec- tion at proximal end is quadraradial to pentaradial and medially to distally is circular. Shell is large (ave. 180 microns in diameter). Pore frames are subcircular and thick. Pores measure an average of eight microns in diameter. Medullary shell is polygonal and latticed, connected to cortical shell by rod-shaped primary bars.
Remarks.—Since there is no trace of a delicate sec- ond cortical shell in specimens of Oriundogutta (?) kingi, it cannot be placed in the genus Inanihella. Or- iundogutta (2) kingi fits the generic description of Or-
Table 18.— Measurements (in um) of Oriundogutta (?) kingt. Num- bers of specimens measured are in parentheses.
MmIini- maxi- mean mum mum
cortical shell diameter 176 140 200 (7) width spine at base 26 24 29 (7) width spine at midspine 16 14 18 (6)
iundogutta Nazarov, 1988, which describes a single thick, porous cortical shell. It is only provisionally placed in the genus, however, because the photograph of the type species is out of focus and morphologic details, like pore shape and spine structure are not discernable.
The figured specimen of Jnanihella (Acanthos- phaera) macroacantha Rist, 1892 (Nazarov, 1988, pl. XII, fig. 1) appears to be conspecific with O. (?) kingi and is synonymized herein. Oriundagutta (?) kingi, n. sp. is not the same species, however, as Acanthos- phaera macroacantha Rist, 1892. Acanthosphaera macroacantha Rist (Rust, 1892, p. 147, pl. XIII, fig. 2), described from the Silurian of Cabrieres, possesses a single shell and the drawing, although fairly nonde- script, shows only one shell. I therefore disagree with Nazarov and Ormiston’s identification. The specimen identified as Inanihella macroacantha by Nazarov and Ormiston (1988, 1993) is not 4. macroacantha Rist. Furthermore, 4. macroacantha Rist does not fit the generic description of Inanihella Nazarov and Ormis- ton, 1984 and should not have been transferred into the genus /nanihella.
Comparison.—Oriundagutta (?) kingi is distin- guished from Oriundagutta (?) varispina, n. sp. by pos- sessing more spines per hemisphere and by possessing spines of equal length.
Measurements.—See Table 18.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—This species is named in honor of P. B. King for his pioneer contributions to the geology of the Marathon uplift.
Designation of types.—Holotype USNM 466302, paratype TMM 1851TX1.
Range and occurrence.—Silurian, Zones 2 through 5 of the Marathon uplift, west Texas, southern Urals, Kazakhstan.
Oriundogutta (?) varispina, new species Plate 6, figures 2, 3; Plate 9, figure 4
Diagnosis.—Large, thickened latticed cortical shell surrounding irregularly shaped medullary shell. Six or more thick, robust spines are interspersed with six or more thinner, smaller spines on cortical surface. Ro- bust spines are grooved at the base and highly tapered.
32 BULLETIN 345
Table 19.—Measurements (in wm) of Oriundogutta (?) varispina. Numbers of specimens measured are in parentheses.
mini- — maxi-
mean mum mum diameter cortical shell 212 178 270 (8) diameter medullary shell 49 46 56 (7) avg. width large spine base 56 43 65 (9) avg. width short spine base 15 10 23 (5) thickness cortical shell 21 14 25 (8)
Comparison.—Pore framework of the cortical shell appears to be slightly more organized than the pores present on Oriundogutta (?) kingi, n. sp. Robust spines have a very similar morphology to spines on Oriun- dogutta (?) kingi (Pl. 9, fig. 4) but are more massive and fewer in number.
Measurements.—See Table 19.
Type locality.—Monument Creek, Marathon uplift, west Texas.
Etymology.—(L.) varius = varied, spina = spine.
Designation of types.—Holotype USNM 466303, paratype TMM 1858TX2.
Range and occurrence.—Late Silurian, Zone 6 in the Marathon uplift, west Texas.
Genus ZADRAPPOLUS Furutani, 1990
Type species.—Zadrappolus yoshikiensis Furutani, 1990
Description.—Inaniguttids with single latticed cor- tical shell and doubled medullary shell having ten or more spines per hemisphere. Spines may be rod-shaped, needle-shaped, or conical.
Zadrappolus yoshikiensis Furutani, 1990 Plate 6, figures 14-16
Description.—Spherical, latticed cortical shell with regularly shaped rounded pores. Spines are well ta- pered at the base and possess deep grooves which ex- tend distally nearly halfway up the spine. Spines strongly tapered at base and number 10 to 15 per hemisphere.
Range and occurrence.—Silurian, Zadrappolus voshikiensis assemblage of the Fukuji Area, Japan; Zones 2 through 5 of the Marathon uplift, west Texas.
Zadrappolus spinosus Furutani, 1990 Plate 6, figure 6; Plate 9, figures 9, 11
Description.— Spherical, single latticed cortical shell with numerous (80 or more) cylindrical spines. Spines are slender and tapered near the base.
Comparison.— Zadrappolus spinosus can be distin- guished from other species of Zadrappolus by pos- sessing numerous slender spines.
Range and occurrence.—Silurian, Spongocoelia par- vus—S. kamitakarensis assemblage, Fukuji Area, Ja-
Table 20.— Measurements (in um) of Zadrappolus lunaris. Num- bers of specimens measured are in parentheses.
mini- — maxi- mean mum mum
diameter cortical shell 168 158 183 (6) diameter medullary shell 43 39 48 (4) avg. spine length 38 34 43 (7) avg. width spine base 17 12 22 (7)
pan; Zones | through 3 of the Marathon uplift, west Texas.
Zadrappolus tenuis Furutani, 1990 Plate 6, figures 10, 12, 13
Description.— Thick spherical latticed cortical shell with 20 to 25 spines visible per hemisphere. Spines are long and cylindrical but strongly tapered at proximal end with three grooves near base.
Range and occurrence.—Late Silurian, Zadrappolus yoshikiensis assemblage, Fukuji Area, Japan; Zones 3 to 6 of the Marathon uplift, west Texas.
Zadrappolus sp. aff. tenuis Furutani, 1990 Plate 6, figure 11
Description.—This form is very similar to Zadrap- polus tenuis Furutani, 1990 but differs in being slightly larger and having more robust, less tapered spines.
Range and occurrence.—Silurian, Zone 2 of the Mar- athon uplift, west Texas.
Zadrappolus lunaris, new species Plate 6, figures 7, 8; Plate 9, figure 8
Diagnosis.— Large, spherical latticed cortical shell with approximately 10 spines per hemisphere. Spines short, conical, and tapered distally. Spine bases are approximately 15 to 20 microns in diameter and have five to six alternating grooves and ridges which are approximately 50% of the spine length. Distal half of spines are rod-shaped and circular in cross section. Medullary shell is latticed and polygonal, connected to cortical shell by non-tapering rod-shaped bars. Pore frames are irregularly polygonal, varying from dia- mond-shaped to pentagonal, and measure five to eight microns diameter.
Comparison.— Zadrappolus lunaris can be distin- guished from other species of Zadrappolus by having shorter, fewer spines.
Measurements.—See Table 20.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) lunaris = of the moon.
Designation of types.—Holotype USNM 466304, paratype TMM 1853TX1.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE
Range and occurrence.—Late Silurian, Zone 6 of the Marathon uplift, west Texas.
Zadrappolus sp. A Plate 6, figure 9
Description. —Latticed cortical shell with 20 or more spines per hemisphere. Spines are tapered and short with four to five grooves at base. Grooves extend nearly halfway up spine.
Comparison.—This species bears close resemblance to Z. lunaris n. sp. but can be distinguished by having nearly twice as many spines. An insufficient number of specimens were recovered to formally describe this taxon.
Range and occurrence.—Silurian, Zone 2 of the Mar- athon uplift, west Texas.
Family PALAEOACTINOSPHAERIDAE, new family
Type genus.— Palaeoactinosphaera, new genus
Diagnosis.—Spherical Spumellarians with two con- centric shells, the cortical and medullary shells. The cortical shell is a latticed sphere and the medullary shell is a latticed polygon or sphere. Six to nine primary spines extend from cortical shell. Spines may be con- ical, straight rods, bladed, or grooved.
Remarks.—The palaeoactinosphaerids comprise a significant part of the Caballos assemblages. These taxa represent between 10 to 50% of the specimens in a given assemblage. Presence or absence of secondary spines distinguishes the two genera within.
Genera included.—Palaeoactinosphaera, Stylacti- nosphaera.
Range and occurrence.—Silurian of the Marathon uplift, west Texas.
Genus PALAEOACTINOSPHAERA, new genus
Type species.—Palaeoactinosphaera antica, new species
Diagnosis.—Spherical to subspherical latticed cor- tical shell with six to eight primary spines and no sec- ondary spines. Primary spines may be rod-shaped, grooved, or bladed, and can be arranged either per- pendicular (orthogonally) or non-perpendicular (ec- centrically) to each other. Primary bars extend inward and connect the cortical shell to the medullary shell. Primary bars are rod-shaped or three-bladed. Pore frames on cortical shell are polygonal to subcircular in outline and vary in their degree of regularity. Short nodes always occur at the juncture of pore frames, but are sometimes not well-preserved. Medullary shell may be either spherical or subspherical.
Ww w
Remarks.—Taxa assigned to this genus possess both orthogonally arranged and eccentrically arranged pri- mary spines. This difference in spine arrangement could be considered by some as a generic level distinction, however sufficient similarity exists in cortical wall structure and spine morphology to warrant assignment within the same genus. These forms had been infor- mally grouped under the term ‘“‘Palaeoactinommid” sensu Holdsworth (1977), a term originally coined to encompass all spherical Spumellariina that did not fall into either the rotasphaerid informal group or Entac- tinacea Riedel, 1967. Palaeoactinosphaera bears ex- ternal resemblance to Paleosphaera Renz, 1990 but can be distinguished by the presence of a medullary shell, whereas Paleosphaera consists of a cortical shell and has no medullary shell. Palaeoactinosphaera also bears a strong resemblance to Entactinosphaera Foreman, 1963, of Devonian age and younger. Both have regu- larly latticed cortical and medullary shells and both possess a diverse primary spine morphology that in- cludes bladed and grooved spines. Entactinosphaera differs in that it possesses an internal spicule within the medullary shell. I have searched for an internal spicular structure in all representative species of Pa- laeoactinosphaera and have found no structure pres- ent. Furthermore, early representatives of the Pa- laeoactinosphaera, such as P. asymmetrica, n. sp. (PI. 4, fig. 13), have an irregularly shaped medullary shell which appears to be a coalescence of branching rays emanating from the base of the primary bars. This manner of medullary shell construction resembles the mode of cortical wall construction observed in the Ro- tasphaeriacea and the medullary shell construction of the inaniguttids. The branching medullary shell struc- ture has also been described by Goodbody (1986) in the general grouping he refers to as the ‘‘Palaeoacti- nommids.”
Biostratigraphically, Palaeoactinosphaera is not as useful as Rotasphaeridae, n. fam. and Inaniguttidae Nazarov and Ormiston, 1984. A few species, such as P. elegantissima, n. sp. and P. crucispina, n. sp., are short-ranging and are locally useful as secondary mark- er taxa, yet others, such as P. antica, n. sp., are longer ranging. Additionally, the external morphology of Pa- laeoactinosphaera strongly resembles some Devonian Entactinosphaera and these similarities may make it dificult to distinguish between the two. Palaeoacti- nosphaera is distinguished from genera of the Inani- guttidae by having a latticed cortical shell with more regularly shaped pores, nodes at pore frame junctures, fewer spines, and spines that may be bladed.
Range and occurrence.—Silurian, Zone | through Zone 6 of the Marathon uplift, west Texas; Cape Phil- lips Formation of the Canadian Archipelago.
34 BULLETIN 345
Table 21.— Measurements (in um) of Pa/aeoactinosphaera antica. Numbers of specimens measured are in parentheses.
Table 23.— Measurements (in um) of Palaeoactinosphaera bar- ricki. Numbers of specimens measured are in parentheses.
mini- = maxi- mean mum mum
diameter cortical shell 103 92 is (5) diameter medullary shell 78 70 86 (2) avg. spine length 44 37 52 (5) avg. width spine base 21 17 25 (5)
Palaeoactinosphaera antica, new species Plate 4, figures 15-17
Diagnosis.—Spherical cortical shell with polygonal to subrounded pore frames. Pore frames exhibit nodes at junctures, are six to nine microns in diameter, and are of moderately uniform size. Six stubby, blunt-end- ed primary spines are arranged orthogonally. Primary spines are rod-shaped and slightly tapered at distal end with six poorly developed grooves at base which extend no further than 25% of the way up the spine. Primary spines are of equal length, equal to approximately 50% of the cortical shell diameter. Subcircular medullary shell is latticed and its diameter is approximately 70% of the cortical shell diameter.
Comparison.— Palaeoactinosphaera antica is distin- guished from the other Pa/aeoactinosphaera by having shorter, thinner, rod-shaped spines with less promi- nent grooves.
Measurements.—See Table 21.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) anticus = foremost, ancient.
Designation of types.—Holotype USNM 466305, paratype TMM 1847TX1.
Range and occurrence.—Silurian, Zones | through 5 of the Marathon uplift, west Texas.
Palaeoactinosphaera asymmetrica, new species Plate 4, figures 12-14
Diagnosis.—Latticed subspherical cortical shell with six to Seven spines arranged eccentrically. Spines range from 45 to 60% of cortical shell diameter and are of varying lenghts. Spines are conical, robust, blunt-end- ed, and have five to six grooves and alternating ridges at the base. Grooves and ridges extend 25 to 35% of the way up the spine and are of unequal size. Medullary
Table 22.—Measurements (in um) of Pa/aeoactinosphaera asym- metrica. Numbers of specimens measured are in parentheses.
MInti- MaXI- mean mum mum
diameter cortical shell 147 104 205 (8) diameter medullary shell 42 40 45 (3) avg. spine length 67 56 76 (7) avg. width spine base 35 30 40 (8)
mini-— maxi-
mean mum mum diameter cortical shell 87 82 91 (6) avg. width spine base 18 17 19 (6) avg. spine length S52 59 (6) avg. width spine grooves at base 13 10 15 (6) avg. width spine ridges 3 2.5 3 (6)
shell is latticed and subcircular with a diameter ap- proximately one-third of the cortical shell diameter. Pores are subrounded to polygonal and but are of a uniform size range of five to eight microns diameter. Nodes occur at pore frame junctures.
Comparison.—Palaeoactinosphaera asymmetrica can be distinguished from other Palaeoactinosphaera by its subcircular shape and its robust, conical spines of unequal size.
Measurements.—See Table 22.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(Gr.) asymmetros = without symme- try.
Designation of types.—Holotype USNM 466306, paratypes TMM 1841TX2, TMM 1842TX1, TMM 1846TX1.
Range and occurrence.—Silurian, Zones | and 2 of the Marathon uplift, west Texas.
Palaeoactinosphaera barricki, new species Plate 4, figures 8, 9
Diagnosis.—Latticed cortical shell with six eccen- trically arranged primary spines. Spines are robust, ta- pered, and have four deep grooves alternating with four prominent blades that extend the entire spine length. The grooves are three to four times as wide as the blades. At spine base, grooves penetrate cortical shell to form pores, and ridges bifurcate to converge with the pore frames on the cortical shell. Pore frames are of non-uniform shape and size, ranging from three to ten microns diameter; two adjacent pore frames may vary as much as 50% in size. Pore frames are generally subrounded and nodes occur at pore frame triple-junc- tures. Primary spines are of slightly unequal size and their length ranges from 50 to 75% of the cortical shell diameter. Thin, rod-shaped primary bars connect cor- tical shell to latticed medullary shell. Medullary shell is latticed, subspherical, and its diameter approxi- mately 40% of the cortical shell diameter.
Comparison.—This species is distinguished from Palaeoactinosphaera elegantissima n. sp. by having primary spines with deeper, wider grooves, and by having pore frames with a non-uniform shape and size.
Measurements.—See Table 23.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 35
Table 24.— Measurements (in um) of Palaeoactinosphaera (?) cru- cispina. Numbers of specimens measured are in parentheses.
Table 25.—Measurements (in um) of Palaeoactinosphaera ele- gantissima. Numbers of specimens measured are in parentheses.
mini- — maxli- mean mum mum
mini- maxi- mean mum mum
diameter cortical shell 190 167 196 (9) diameter medullary shell 75 F2 76 (3) avg. spine width 31 24 34 (9) avg. width spine groove UES) 7 8 (9) avg. width spine blade 9 9 10 (9)
diameter cortical shell 126 115 130 (7) avg. spine length 70 63 73 =«(7) avg. width spine base 35 33 36 =—(7) avg. width spine groove at base 7 6 i @) avg. width spine ridge 8 8 8 (7)
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—This species is named in honor of Dr. Jim Barrick for his contributions to improving the chronostratigraphic control of the Caballos Novacu- lite.
Designation of types.—Holotype USNM 466307, paratype TMM 1842TX2.
Range and occurrence.—Silurian, Zones 1? through 3 of the Marathon uplift, west Texas.
Palaeoactinosphaera (?) crucispina,new species Plate 5, figures 11, 12; Plate 9, figure 5
Diagnosis.—Large, spherical latticed cortical shell with large, thickened subcircular pores of varying size. Nodes occur on pore-frames at pore triple-junctures. Six robust, three-bladed spines with deep grooves are arranged orthogonally. Spines are long, non-tapering and triaxial in cross section. Latticed medullary shell is subquadrate with large irregularly shaped pores. Three-bladed primary bars with a triaxial cross section connect medullary shell to cortical shell. Primary bars branch at base and anastomose into pore-frames of medullary shell (Pl. 5, fig. 12). Medullary shell is ap- proximately 50% the diameter of cortical shell.
Remarks.—Palaeoactinosphaera (?) crucispina is a large, robust form which is very distinct due to its large pores and long bladed spines. The pore frames are nodose and subcircular in shape, yet they are substan- tially larger that the pores in other species of Palaeoac- tinosphaera (roughly twice the diameter). The long, nontapering bladed spines are more similar to the blad- ed spines found in Devonian Entactiniidae Riedel, 1967 than to the spine morphology found in other Palaeoac- tinosphaera, yet the internal spicule characteristic of Entactiniidae was not observed in this species.
Measurements.—See Table 24.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) crucis = cross, spina = spine.
Designation of types.—Holotype USNM 466308, paratypes TMM 1846TX2, TMM 1856TX1.
Range and occurrence.—Silurian, Zone | and low- ermost Zone 2 of the Marathon uplift, west Texas.
Palaeoactinosphaera elegantissima, new species Plate 4, figures 10, 11
Diagnosis.—Latticed cortical shell with pentagonal to subrounded pore frames and six robust primary spines. Pores are fairly uniform in shape and size rang- ing from three to eight microns diameter. Nodes occur on pore frames at pore triple-junctures. Spines possess five to six grooves and alternating ridges which extend the length of the spine. Spines are more strongly ta- pered at distal ends, giving a bullet-shaped appearance. Grooves are deep yet narrow and alternate with round- ed ridges which are of approximately equal width to the grooves. All primary spines are of equal length, equal to approximately 60% of the cortical shell di- ameter. Rod-shaped primary bars connect cortical shell to subspherical latticed medullary shell with a diameter of approximately 35% of cortical shell diameter.
Comparison.—This species is distinguished from P. asymmetrica, n. sp. by possessing narrowly grooved spines which are of equal length, by having larger pore frames, and a more circular cortical shell. It also can be distinguished from P. barricki, n. sp. by possessing more narrowly grooved spines, spines of equal length, and more uniform pore frames.
Measurements.—See Table 25.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) elegantissimus = very fine, choice.
Designation of types.—Holotype USNM 466309, paratypes TMM 1850TX5, TMM 1848TX1.
Range and occurrence.—Silurian, lower half of Zone 2 of the Marathon uplift, west Texas.
Palaeoactinosphaera (?) octaspina, new species Plate 4, figure 7; Plate 9, figure 3
Diagnosis.—Latticed spherical cortical shell with pentagonal to subrounded pore frames and eight slen- der primary spines. Pores are fairly uniform in shape and size ranging from five to seven microns diameter. Nodes occur on pore frames at pore triple-junctures. Primary spines of equal length, equal to approximately half of the cortical shell diameter. Spines are slightly tapered and circular in cross section, except at base which is tetraradiate in cross section due to four collar
36 BULLETIN 345
Table 26.— Measurements (in um) of Pa/aeoactinosphaera (?) oc- taspina. Numbers of specimens measured are in parentheses.
mini- maxi-
mean mum mum diameter cortical shell 139 125 149 (7) diameter medullary shell 54 52 56 (2) avg. spine length 49 45 54 (7) avg. width spine base 12 9 14 (7)
pores which extend up the spine to form four grooves and alternating ridges. Grooves and ridges extend dis- tally no further than 10% of the spine length. Primary spines are of approximately equal length, equal to ap- proximately 35 to 40% of the cortical shell diameter. Rod-shaped primary bars connect cortical shell to lat- ticed spherical medullary shell. Diameter of medullary shell is approximately 40% cortical shell diameter.
Remarks.—This species is placed in Palaeoactinos- phaera, n. gen. only tentatively because the medullary shell is spherical. Other Palaeoactinosphaeridae have a subspherical medullary shell; P. (?) octaspina is a late species, however, and increased sphericity of the med- ullary shell may be a derived characteristic. A spherical medullary shell is a common characteristic in Entac- tinosphaera Foreman, 1963, and since the inside of the medullary shell was observed in only one specimen it is possible that P. (?) octaspina is an Entactinosphaera whose internal spicule has not been preserved.
Comparison.—This species is distinguished from Palaeoactinosphaera antica, n. sp. by possessing eight spines which are thinner and slightly longer. It may be distinguished from Palaeoactinosphaera asymmetrica, n. sp. by having a more circular outline, more slender spines, and pore frames which are more uniform in shape and size.
Measurements.—See Table 26.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) octo = eight, spina = spine.
Designation of types.—Holotype USNM 466314, paratype TMM 184S5TX1.
Range and occurrence.—Late Silurian, upper half of Zone 2 through Zone 6 of the Marathon uplift, west Texas.
Genus STYLACTINOSPHAERA, new genus
Type species.— Stylactinosphaera prima, new species
Diagnosis.—Latticed medullary shell surrounded by thickened, spinose cortical shell with six to eight robust primary spines. Rod-shaped primary bars extend from cortical shell to latticed, subrounded medullary shell. Primary spines are conical with shallow grooves and alternating ridges at proximal end. Grooves and alter- nating ridges partially extend up the length of the spine.
Table 27.—Measurements (in um) of Stylactinosphaera prima. Numbers of specimens measured are in parentheses.
mini- maxi- mean mum mum
diameter cortical shell 185 149 242 (7) diameter medullary shell 59 56 65 (3) avg. length primary spine 82 65 93 (7) avg. length secondary spine 35 28 42 (6) avg. width primary spine base 34 28 39 (7)
The cortical shell is covered by numerous secondary spines (20 or more per hemisphere) that are less than 75% the size of the primary spines. Grooves and al- ternating ridges occur at proximal end of secondary spines and partially extend up the spine length.
Remarks.—Stylactinosphaera and Palaeoactinos- phaera have similar primary spine morphology, spine distribution, and medullary shell morphology, but dif- fer in that Palaeoactinosphaera possesses numerous secondary spines that substantially alter the appear- ance of the cortical shell. The secondary spines in Sty- lactinosphaera are numerous and robust so that poor preservation should not completely remove them. Poorly preserved specimens of Styv/actinosphaera have a thickened cortical shell that has an irregular, bumpy appearance and look distinctly different from Pa- laeoactinosphaera, which has uniform pore frames and delicate nodes.
Range and occurrence.—Silurian, Zone | and lower Zone 2 of the Marathon uplift, west Texas.
Stylactinosphaera prima, new species Plate 4, figures 18, 19
Diagnosis.— Large shell with thickened latticed cor- tical shell and numerous secondary spines. Secondary spine development gives cortical shell a thickened, ir- regularly porous appearance and obscures shape and size of pore frames. Eight blunt-ended robust primary spines extend from cortical shell and are grooved at the base. Five to six grooves and alternating ridges extend 25 to 30% of the way up the spine from prox- imal end. Grooves are not of uniform size, one groove being shorter, thinner, and shallower than the adjacent groove, and ridges are approximately equal width. Sec- ondary spines are numerous (25 or more per hemi- sphere) and possess the same conical form as the pri- Mary spines, but are one-half the length and approximately one-third the thickness. Medullary shell is subspherical and latticed and is approximately 30% the diameter of the cortical shell.
Comparison.— Stylactinosphaera prima occurs with Palaeoactinosphaera asymmetrica, n. sp. and has a similar primary spine structure and polygonal med- ullary shell. It differs by possessing a thickened cortical
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 37
shell and by possessing numerous robust secondary spines.
Measurements.—See Table 27.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) primus = first.
Designation of types.—Holotype USNM 466310, paratype TMM 1846TX3.
Range and occurrence.—Silurian, Zone | and lower Zone 2 of the Marathon uplift, west Texas.
Family PALAEOSCENIDIIDAE Riedel, 1967, emended Holdsworth, 1977, emended Furutani, 1990
Genus GOODBODIUM Furutani, 1990
Type species.—Palaeoscenidium flammatum Good- body, 1986
Goodbodium sp. indet. Plate 5, figures 5, 6
Description.—Test possesses four basal spines and four apical spines. Tent-like layer skirts the upper part of the basal spines.
Remarks.—Specimens observed were poorly pre- served. The seemingly solid wall of the tent-like layer may be caused by quartz overgrowth of spinules and lamellae which make up the less solid tent-like shell layer in the type material of Goodbodium.
Range and occurrence.—Silurian, Japan; Canadian Archipelago; the Marathon uplift, west Texas.
Genus HOLDSWORTHUM Furutani, 1990
Type species.—Holdsworthum japonicus Furutani, 1990
Holdsworthum sp A. Plate 5, figure 7
Description.—Two short apical spines and three bas- al spines. Loose net connects basal spines to form an open conical net. A lateral elongate spine (not pre- served in figured specimen) projects from the side of the net and curves downward.
Remarks.—This form possesses a lateral spine and loose netting similar to that in the figured specimens of Holdsworthum (Furutani, 1990, pl. 8, figs. 8-10). It differs only in that no lamellae develop in the proximal part of the net to form a solid shell. Only two specimens were recovered; insufficient material to formally de- scribe this taxon.
Family INCERTAE SEDIS
Remarks.—Included are the genera Bipylospongia, n. gen. and Praespongocoelia, n. gen. that do not com- pletely fit the description of any one family. They share
Table 28.— Measurements (in um) of Bipylospongia rudosa. Num- bers of specimens measured are in parentheses.
mini-) Maxi- mean mum mum
axial diameter cortical shell 215 177 ~=«260; ~(7) equatorial diameter cortical shell 180 149 214 (7) width larger pylome 57 41 68 (5) width smaller pylome 36 31 45. (5)
characteristics with both Actinommidae and Spon- guridae. The genera Cenosphaera Ehrenberg, 1854 and Stylosphaera Ehrenberg, 1854 are also included. They share characteristics with the Actinommidae (Haekel) Riedel, 1967, yet Holdsworth (1977) believes that the Paleozoic Actinommids, or ‘Paleoactinommids,’ are phylogenetically distinct. At present, these taxa are treated as genera Insertae Sedis.
Genus BIPYLOSPONGIA, new genus
Type species.— Bipylospongia rudosa, new species
Diagnosis.—Test ovate consisting of a spongy cor- tical shell with a hollow internal cavity and no med- ullary shell. Two pylomes occur; one at each pole which are often unequal in size. Pylomes are surrounded by five to eight spines or flanges of varying size. Cortical surface may or may not be covered with spongy nodes.
Range and occurrence.—Silurian, Zones 1 and 2 of the Marathon uplift, west Texas.
Etymology.—(L.) bi = two, spongia = sponge (Gr.) pylo = orifice.
Bipylospongia rudosa, new species Plate 7, figures 6-9
Radiolarian genus nova A Noble, 1993b, p. 278, pl. 1, fig. 5.
Diagnosis.—Shell is ovate with two pylomes and covered with coarse spongy nodes. Pylomes are at each pole and are of unequal width. Each pylome is orna- mented with five to eight flanged spinose projections. Shell wall is thick and spongy, averaging 15 microns thickness. Shell is hollow in center.
Comparison.—This species can be distinguished from Devoniglansus unicus Wakamatsu et al., 1990 by hav- ing two pylomes and have a hollow spongy cortical shell, as opposed to the solid spongy cortical shell of D. unicus.
Measurements.—See Table 28.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) ruidus = rough.
Designation of types.—Holotype USNM 466311, paratype TMM 1841TX3.
Range and occurrence.—Silurian, Zones | and 2 of the Marathon uplift, west Texas.
38 BULLETIN 345
Table 29.—Measurements (in um) of Praespongocoelia fusiforma. Numbers of specimens measured are in parentheses.
mini-- maxi- mean mum mum
axial diameter cortical shell 206 1/233 (9) equatorial diameter cortical shell 161 149 177) (9) length long spine DAF, 177 251 (8) length short spine 96 84 M2) AG)
Genus PRAESPONGOCOELIA, new genus
Type species.—Spongocoelia parvus Furutani, 1990
Diagnosis.— Large robust subspherical to ovate shell with two robust bipolar spines. Spines are fat, wide, blunt-ended, and of unequal length. Base of spines have collar grooves and are slightly constricted at base. Shell consists of a single thickened layer of spongy cortical shell approximately 15 microns thick. Cortical shell may be ornamented with short hispid projections. In- terior of shell is hollow; no internal structure has been observed.
Comparison.— This genus bears a strong superficial resemblance to Pseudospongoprunum (?) tauversin. sp. but differs in the wall structure. Spongovalis has mul- tiple concentric layers which fill most of the internal part of the shell whereas Praespongocoelia has a large internal cavity with only one thickened spongy cortical shell. In the event that the internal structure should be obscured by recrystallization, Praespongocoelia can be distinguished by a slightly finer spongy meshwork.
Range and occurrence.—Silurian, Spongocoelia par- vus—S. kamitakarensis Zone of the Fukuji Area, Japan; ? Kurosegawa Tectonic Zone of Japan; Zone 2 of the Marathon uplift, west Texas.
Praespongocoelia parva (Furutani), emended herein Plate 7, figures 1-4
Spongocoelia parvus Furutani, 1990, p. 47, pl. 9, figs. 5-6, pl. 10, figeall Spongocoelia parvus Furutani. Noble, 1993b, p. 278, pl. 1, fig. 6.
Emended diagnosis.—Test subspherical, spines are offset from poles to form an angle approximately 165— 170 degrees. Spines are blunt at end. Smaller spine is 30 to 40% shorter than larger spine. Larger spine is slightly shorter than long axis of cortical shell. Collar grooves extend approximately 10% up the spine and form a distinct constriction at base. Internal structure is poorly preserved in these specimens but shell ap- pears to consist of a single thickened layer with a large internal cavity.
Comparison.—This species is distinguished from Pseudospongoprunum (2?) tauversi by having a less elon- gate cortical shell and slightly longer spines which are not as conical and are blunter at the ends. Size of pores
in spongy cortical shell is slightly smaller than those in P. (?) tauversi.
Range and occurrence.—Silurian, Zone 2 of the Mar- athon uplift, west Texas; Japan.
Praespongocoelia fusiforma, new species Plate 7, figures 11, 12
Spongocoelia sp. nova A Noble, 1993b, p. 278, pl. 1, fig. 7.
Diagnosis.—Test subcircular approaching spindle- shaped, spines are very robust and offset from poles to form an angle approximately 175 degrees. The larger spine is elongate, approximately 3 x the length of the smaller spine, and is 10 to 15% longer than long di- mension of the cortical shell.
Comparison.—This species is distinguished from species Praespongocoelia parva Furutani, 1990 by hav- ing a spindle-shaped cortical shell which is slightly smaller, and by its long polar spine.
Measurements.—See Table 29.
Type locality.—East Bourland Mountain, Marathon uplift, west Texas.
Etymology.—(L.) fusiformis = spindle-shaped.
Designation of types.—Holotype USNM 466312, paratype TMM 1855TX1.
Range and occurrence.—Silurian, lower part of Zone 2 of the Marathon uplift, west Texas.
Genus CENOSPHAERA Ehrenberg, 1854
Type species.—Cenosphaera plutonis Ehrenberg, 1854 (by monotypy)
Cenosphaera hexagonalis Aberdeen, 1940 Plate 5, figure 10; Plate 9, figure 2 Cenosphaera aberdeenae Furutani, 1990, p. 51, pl. 11, fig. 8, pl. 12,
fig. 9. Cenosphaera aberdeenae Furutani. Noble, 1993b, p. 278, pl. 1, fig. 9.
Description.—Single latticed shell with large open pores and robust pore frames. Eight short spines pro- trude and are arranged in pairs.
Remarks.—This taxon occurs in virtually all sam- ples of the Silurian Caballos fauna. It makes its last appearance up-section of the material described in this paper, but does not extend into the Middle and Late Devonian part of the Caballos sections. Slight mor- phological variations can be seen up-section. Younger specimens occurring in Zones 5 and 6 appear to have longer spines and almost imperceivably thinner pore frames than specimens from the older zones.
Furutani (1990) proposes Cenosphaera aberdeenae as a replacement name for C. hexagonalis Aberdeen, 1940. I suspect that Furutani has taken taken this course of action because he thinks the original photos are sufficiently poor and unclear for C. hexagonalis to be
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 39
considered nomen dubium. Aberdeen’s photos are taken from thin-sections and many show only a cross section of the species with little surface detail represented. Cenosphaera hexagonalis has a relatively simple shell construction with large, open pores and it is the only species of Aberdeen’s that I can identify with certainty. Therefore, the replacement name is not necessary; C. hexagonalis is both valid and available.
Range and occurrence.—Silurian, Zones | through 6 and younger (see remarks) of the Marathon uplift, west Texas; Canadian Archipelago; Japan.
Genus STYLOSPHAERA Ehrenberg Type species.—Stylosphaera hispida Ehrenberg, 1854
Stylosphaera (?) magnaspina, new species Plate 5, figures 2-4
Stylosphaera ? sp. B Furutani, 1990, p. 39, pl. 5, figs. 7, 8. Stylosphaera ? sp. C Furutani, 1990, p. 40, pl. 6, figs. I, 2 ° Stylosphaera quasirobusta Aberdeen, 1940, p. 135, pl. 21, fig. 5.
Diagnosis.—Spherical to slightly ellipsoidal cortical shell with two robust, grooved, polar spines. Spines are grooved the entire length and are rounded at distal end. Spine diameter is approximately 50% of cortical shell diameter. Medullary shell is a spherical lattice connected to polar spines by rods.
Remarks.—The internal structure of the medullary shell could not be determined, and it is not known if there is an internal spicule. The presence of such a spicule would place this taxon within Entactiniidae Riedel, 1967. Until the nature of the internal structure is determined, this taxon remains as incertae sedis. Stylosphaera quasirobusta Aberdeen, 1940 may be synonymous with this taxon, yet there is insufficient morphologic detail preserved in the Aberdeen’s syn- type to make a positive determination.
Measurements.—See Table 30.
Type locality.—Payne Hills, Marathon uplift, west Texas.
Etymology.—(L.) magnus = large, spina = spine.
Designation of types.—Holotype USNM 466313, paratype TMM 1852TX|1.
Range and occurrence.—Late Silurian, Zone 4, Mar- athon uplift, west Texas; Osobudani Valley, central Japan.
Spumellarian indet. sp. A Plate 5, figure |
Description.—Latticed cortical shell with three, pos- sibly four, robust triradiate bladed spines. Spines are tapered and sharp-ended. Rod-shaped primary bars attach spherical latticed medullary shell to cortical shell.
Remarks.—The wall structure of cortical and med- ullary shells is very similar to co-occurring species Sty-
Table 30.— Measurements (in um) of Stylosphaera (?) magnaspina. Numbers of specimens measured are in parentheses.
mMIni- maxi- mean mum mum
diameter cortical shell 181 167 196 (6) diameter medullary shell 98 88 112 (3) avg. length primary spine 189 158 237 (5) width spine base 69 60 74 (6) total length $12 474 539 (3)
losphaera (?) magnaspina, n. sp. This suggests that these two may be related. No specimens were found where the inside of the medullary shell could be viewed. Further examination is necessary to determine the na- ture of shell construction.
Range and occurrence.—Late Silurian, upper Zone 3 through lower Zone 5 of the Marathon uplift, west Texas.
Spumellarian indet. sp. B Plate 5, figures 8, 9
Description. —Spherical shell composed of loose, ir- regularly porous meshwork. Diameter of internal cav- ity is approximately 50% of shell diameter with shell wall thickness comprising the other 50%. Eight to ten short conical bladed spines occur irregularly on cortical shell. Bases of spine blades join with meshwork of cortical shell. Pores are large, rounded and are non- uniform in shape and size. Pore size between adjacent pores may differ by a factor of two.
Range and occurrence.—Silurian, Zone 2 and lower Zone 3 of the Marathon uplift, west Texas.
APPENDIX Radiolarian Sample Descriptions
The precise location of the base of each measured section is given in Universal Transverse Mercator (UTM) coordinates and latitude/longitude coordi- nates. Intervals for each sample are given in meters above base of section. Sample numbers are laboratory numbers assigned when samples were processed for radiolarians. Sample numbers that are followed by a ““c”? are composite samples of two to four beds, com- monly adjacent beds, within a 30 to 130 cm interval.
Section name: Payne Hills section
Topographic map: Beckwith Hills Quadrangle (7.5’)
UTM: 13RFD57603975 = base of section, top of lower novaculite
Lat/Long: 30°10'50”N/103°21'47"W
General description: Located on the west limb of an upright south- plunging open syncline in the northwest region of the Payne Hills on the Paisano Ranch. Section dips steeply to the southeast. Caballos Novaculite is approximately 75 m thick with a thin (4 m) lower novaculite and a thin (8 m) upper novaculite. Lower chert and shale member is composed of laminated tan to gray weathering porcel- lanite, chert, and siliceous shale with beds ranging from | to 15 cm thick.
40 BULLETIN 345
322c: Caballos Novaculite. Laminated tan siliceous mudstone al- ternating with medium gray chert beds 1-3 cm thick. Composite of 3 beds within 9.5-10 m
323c: Caballos Novaculite. Laminated tan to pale gray porcellanite/ siliceous shale. Beds 2-3 cm thick. Composite of 3 beds within 13-13.5 m
324c: Caballos Novaculite. Tan laminated porcellanite. Composite of 3 beds within 16.5-17.5 m
325c: Caballos Novaculite. Tan and white chert. Porcellanite lam- inated. Beds 10 cm thick. Composite of 3 beds within 19-19.5 m
326c: Caballos Novaculite. Gray, tan, and white laminated chert/ porcellanite with beds 8-15 cm thick. Composite of 2 beds within 21-21.7 m
327c: Caballos Novaculite. Gray, tan, and white laminated chert/ porcellanite with beds 6-15 cm thick. Composite of 2 beds within 23.5-24 m
328: Caballos Novaculite. Gray, tan, and white laminated chert/ porcellanite bed at 24.5 m
329: Caballos Novaculite. Gray, tan, and white laminated chert/ porcellanite bed at 26.5 m
330: Caballos Novaculite. Gray, tan, and white laminated chert/ porcellanite beds 6-15 cm thick. 2 beds within 28-28.3 m
331: Caballos Novaculite. Gray-white laminated chert bed at 29 m
332: Caballos Novaculite. Gray chert bed 5 cm thick at 31.5 m
Section name: Payne Hills II section (PH2)
Topographic map: Beckwith Hills Quadrangle (7.5’)
UTM: 13RFD57263962 = base of section, lowest exposed bed of Caballos chert
Lat/Long: 30°10'69"N/103°21'00"W
General description: Section of Caballos Novaculite located at the top of the ridge to the east of the road at the pass through the Payne Hills on the Paisano Ranch. Base of Caballos Novaculite and top of underlying Maravillas Limestone is covered. The Caballos is ap- proximately 70 m thick with no lower novaculite and a thin (3 m) upper novaculite. Lower chert and shale member as small thrust faults at the base.
077: Caballos Novaculite. Tan and brown laminated chert. Three beds sampled 1-2 cm thick, 70 cm above base of lowest exposed chert bed (70 cm above base of Caballos?). No novaculite is present in section.
Section name: Sulphur Springs
Topographic map: Rock House Gap quadrangle (7.5')
UTM: 13RFD54503289 = base of section, top of lower novaculite
Lat/Long: 30°07'07"N/103° 21'00”W
General description: Section of west-dipping Caballos Novaculite in western basin margin near Sulphur Springs on the Roberts Ranch. Caballos section is approximately 90 m thick with a thin lower novaculite (6 m) and no upper novaculite. Top of novaculite is conglomeratic with the uppermost beds of white novaculite mpped up and plastically incorporated with granule-sized to cobble-sized lumpy black manganiferous chert. Some brecciation in black chert lumps with cavity infilling of orange ironstone. Lowermost exposed bed of lower chert and shale pinches and swells in what appears to be soft-sediment deformation. Lower chert and shale is tan to gray weathering laminated chert ranging from 2 cm to 15 cm thick. Pinch and swell beds occur throughout the section every few m that appear to be caused by soft sediment deformation.
386: Caballos Novaculite. Dark blue-gray glassy chert with opaque tan pinstripe laminations that pinches and swells. Bed 4 cm thick at 1.5m
391c: Caballos Novaculite. Tan and blue-gray laminated chert and porcellanite. Composite of 3 beds within 12.5-13.5 m
Section name: McKnight (locality 9 of Fig. 0.1)
Topographic map: Marathon Quadrangle (7.5’)
UTM: 13RFD72394365 = base of section, top of lower novaculite
Lat/Long: 30°12'53”N/130°12'33”W
General description: Section of Caballos Novaculite on a poorly exposed low-lying ridge on the northeast corner of the intersection between U.S. highways 90 and 385 on the McKnight Ranch. Lower novaculite is thick (24 m) and is overlain by a poorly exposed se- quence of tan to gray weathering laminated chert and shale beds ranging from 6 cm to 30 cm thick. A 50 cm conglomeratic bed occurs approximately 1.5 m above the base of the lower chert and shale. Pinch and swell beds occur up section at 9 m above the base. Upper novaculite is absent.
430c: Caballos Novaculite. Laminated tan and gray chert beds. Composite within 3-4 m
431c: Caballos Novaculite. Laminated tan and gray chert. Com- posite within 5-5.5 m
432c: Caballos Novaculite. Laminated tan and gray chert. Com- posite within 7-7.5 m
434c: Caballos Novaculite. Laminated tan and blue-gray chert, 15- 20 cm thick beds. Composite within 10.5-12 m
435c: Caballos Novaculite. Laminated tan and blue-gray chert, 15- 20 cm thick beds. Composite within 14.3-15.5 m
436: Caballos Novaculite. White and tan laminated chert bed 20- 30 cm thick at 17 m
Section name: Monument Creek (locality 7 of Fig 0.1)
Topographic map: Beckwith Hills Quadrangle (7.5’)
UTM: 13RFD58623406 = base of section, top of lower novaculite
Lat/Long: 30°07'45"N/103°21'10"W
General description: South to southeast-dipping section of Cabal- los Novaculite approximately 125 m thick exposed along a ridge runing northwest of Road Canyon. Section was measured on a slope along the south side of an intermittent stream drainage. The exposed section of Caballos Novaculite has a thick lower novaculite (38 m) anda thin upper novaculite (4 m). The lower chert and shale member consists of laminated thin-bedded greenish gray chert and porcel- lanite and olive siliceous mudstone with beds between 5 and 15 cm thick. Pale pink weathering siliceous shale occurs from 2.5 to 3 m above the top of the lower novaculite.
090: Caballos Novaculite. Dark gray and light green laminated chert bed 6-8 cm thick at 2 m
355: Caballos Novaculite. Olive green porcellanite bed 6 cm thick at3.5m
356: Caballos Novaculite. Two olive green porcellanite beds 7 cm thick at S-5.2 m
357c: Caballos Novaculite. Green chert beds 12-15 cm thick. Com- posite 10-10.5 m
095: Caballos Novaculite. Gray-green porcellanite bed 6 cm thick at 11.8 m.
097: Caballos Novaculite. Green and white laminated chert beds 2 cm thick at 13.4 m
358: Caballos Novaculite. Green and tan banded chert beds 5 cm thick at 13.9-14 m
882: Caballos Novaculite. Green and tan laminated chert bed 2 cm thick at 14.3 m
359c: Caballos Novaculite. Green laminated chert bed 5 cm thick at 14.6 m
Section name: East Bourland (locality 11 of Fig. 0.1) Topographic map: Simpson Springs Mountain Quadrangle (7.5’) UTM: 13RFD63142862 = base of section, top of lower novaculite Lat/Long: 30°04'45"N/103°18'30"W
General description: West-dipping section of Caballos Novaculite
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 41
approximately 165 m thick on the west limb near the nose of a south-plunging anticline, East Bourland Mountain, on the Paisano Ranch. Lower novaculite is thick (26 m) and the upper novaculite is absent. Lower chert and shale member consists of laminated dark gray to tan weathering chert and porcellanite ranging from 2 to 10 cm thick. The lower few meters are bluish gray.
212c: Caballos Novaculite. Gray-blue and green mottled chert 3-5 cm beds. Composite of 2 beds within 0-0.5 m
213c: Caballos Novaculite. Gray-blue and green mottled chert 3-5 cm beds. Composite of 2 beds within 2-2.5 m
214: Caballos Novaculite. Gray-blue and green mottled chert bed at 3.5m
215c: Caballos Novaculite. Gray and black laminated chert beds 4— 8 cm thick. Composite of 2 beds within 5-5.5 m
216c: Caballos Novaculite. Gray and black laminated chert beds 4— 8 cm thick. Composite of 2 beds within 5.5-6 m
217: Caballos Novaculite. Gray, tan, and black laminated chert and porcellanite bed at 6.5 m
218: Caballos Novaculite. Gray, tan, and black laminated chert and porcellanite bed at 9 m
219: Caballos Novaculite. Gray laminated chert at 11 m
220: Caballos Novaculite. Gray, black, green, and tan chert beds 6- 10 cm thick at 13.5 m
223: Caballos Novaculite. Gray and green chert bed 8 cm thick at 17.6 m
224: Caballos Novaculite. Black and and tan laminated bed 4 cm thick with tanish gray nodules at 18 m
225: Caballos Novaculite. Two beds of laminated green, black, and tan chert 7-10 cm thick at 18.5-18.7 m
226: Caballos Novaculite. Two beds of laminated green, black, and tan chert at 19.4-19.6 m
227c: Caballos Novaculite. Two beds laminated green, dark gray, and tan chert at 20.5 and 21 m
228: Caballos Novaculite. Laminated green, dark gray, and tan chert at 21.5 m
Section name: Wood Hollow (locality 16 of Fig. 0.1) Topographic map: Pena Blanca Mountains Quadrangle (7.5’)
UTM: 13RFD71463001= base of section, top of lower novaculite
Lat/Long: 30°05'26"N/103°13'25”W
General description: West-dipping near-vertical section of poorly exposed Caballos Novaculite on south side of the road by Wood Hollow Tank on the Paisano Ranch. Caballos Novaculite is ap- proximately 80 m thick with a thin lower novaculite (7 m) and a thin upper novaculite (4 m). Lower chert and shale is a dark gray to greenish weathering laminated chert and porcellanite with beds rang- ing from 5 to 20 cm thick. Lower chert and shale member is barely exposed and in a flat area with nearly the same topographic relief as the road.
395c: Caballos Novaculite. Greenish blue and gray laminated chert beds 3-8 cm thick. Composite of 3 beds within 8-8.5 m
396c: Caballos Novaculite. Greenish blue and gray laminated chert beds 3-8 cm thick. Composite of 3 beds within 8.5—9 m
397: Caballos Novaculite. Two beds of greenish blue and medium gray laminated chert beds 3-8 cm thick at 9.4-9.6 m
398: Caballos Novaculite. Two beds of greenish blue and medium gray laminated chert beds 3-8 cm thick at 9.7-9.8 m
399: Caballos Novaculite. Greenish blue and medium gray lami- nated chert bed at 11 m
400: Caballos Novaculite. Greenish blue and medium gray lami- nated chert bed at 11.6 m
401: Caballos Novaculite. Greenish blue, medium gray, and black laminated chert bed at 12.5 m
403: Caballos Novaculite. Greenish blue, medium gray, and black laminated chert bed at 13 m
407c: Caballos Novaculite. Medium gray and black banded chert (bands 1-3 cm) bed at 14 m
408c: Caballos Novaculite. Gray-green, and black banded chert beds. Composite within 14.5-15 m
409c: Caballos Novaculite. Gray-green and black banded chert beds 7-13 cm thick. Composite within 15-15.5 m
410: Caballos Novaculite. Gray-green and black banded chert beds 7-13 cm thick. Composite within 15.5-16 m
411: Caballos Novaculite. Gray-green and black banded chert beds 7-13 cm thick. Composite within 18-18.5 m
REFERENCES CITED
Aberdeen, E.
1940. Radiolarian fauna of the Caballos Formation, Marathon Basin, Texas. Journal of Paleontology, vol. 14, pp. 129- 139.
Aitchison, J.C.
1990. Significance of Devonian—Carboniferous radiolarians from accretionary terranes of the New England Orogen, eastern Australia. Marine Micropaleontology, vol. 15, pp. 365- 378.
1991. Kurosegawa terrane: disrupted remnants of a low latitude Paleozoic terrane accreted to SW Japan. Journal of South- east Asian Earth Sciences, vol. 6, pp. 83-92.
Arbenz, J. K.
1989. The Ouachita system, in Bally, A. W., and Palmer, A. R. [eds.], The geology of North America—An overview. Geo- logical Society of America, Boulder, Colorado, vol. A, pp. 371-396.
Baker, C. L., and Bowman, W. F.
1917. Geologic exploration of the southeastern Front Range of
Trans-Pecos Texas. Texas University Bulletin, No. 1753, pp. 61-77. Barrande, J. 1850. Graptolites de Boheme. Prague, vi, 74 p., pl. 1-4.
Barrick, J. E. 1977. Mulitelement simple-cone conodonts from the Clarita For- mation (Silurian), Arbuckle Mountains, Oklahoma. Geo- logica et Palaeontologica, vol. 11, pp. 47-68.
1987. Conodont biostratigraphy of the Caballos Novaculite (Early Devonian-Early Mississippian), northwestern Marathon uplift, west Texas, in Austin, R. L. [ed.], Conodonts: In- vestigative Techniques and Applications. British micro- paleontology series, Ellis Horwood, LTD, pp. 120-135.
Barrick, J. E., and Klapper, G.
1976. Mulitelement Silurian (late Llandoverian—Wenlockian) conodonts of the Clarita Formation, Arbuckle Mountains, Oklahoma, and phylogeny of Kockelella. Geologica et Pa- laeontologica, vol. 10, pp. 59-100.
Blome, C. D. 1984. Upper Triassic Radiolaria and radiolarian zonation from western North America. Bulletins of American Paleontol- ogy, vol. 85, No. 318, 88 p.
Blome, C. D., and Albert, N. 1985. Carbonate concretions; an ideal sedimentary host for mi- crofossils. Geology, vol. 13, No. 3, pp. 121-215.
42 BULLETIN 345
Blome, C. D., and Reed, K.
1993. Acid processing of pre-Tertiary radiolarian cherts and its impact on faunal content and biozonal correlation. Geol- ogy, vol. 21, pp. 177-180.
Branson, E. B., and Mehl, M. G.
1933. Conodonts from the Bainbridge (Silurian) of Missouri.
University of Missouri Studies, vol. 8, pp. 39-52, 3 pls. Calkins, G. N.
1909. Protozoology. Lea & Febiger, New York and Philadelphia,
349 p., pls. 14. Cheng, Y. N.
1986. Taxonomic studies on Upper Paleozoic Radiolaria. Na- tional Museum of Natural History Special Publication number |, Taiwan, R.O.C., 311 p.
Coley, K. L.
1987. Structural evolution of the Warwick Hills, Marathon Basin, west Texas. The University of Texas at Austin, unpub- lished M.A. Thesis, 141 p.
Cotera, A. S.
1969. Petrology and petrography of the Tesnus Formation, in McBride, E. F. [ed.], Stratigraphy, sedimentary structures, and origin of flysch and pre-flysch rocks, Marathon Basin, Texas. Dallas Geological Society Guidebook, pp. 66-71.
Ehrenberg, C. G.
1838. Uber die Vildung der Kreidefelsen und des Kreidemergels durch unsichtbare Organismen. Kgl. Akad. Wiss. Berlin, Abh. Jahrg. 1838, pp. 59-147, pls. 1-4.
1854. Das organische Leben des Meeresgrundes: Weitere Mitth- eiling uber die aus grossen Meerstiefen gehoben Guna- Massen; Charakteristik der neuen mikroskopischen Or- ganismen des tiefen atlantischen Oceans. Kgl. Akad. Wiss. Berlin, Ber. Jahrg. 1854, pp. 235-251.
Flawn, P. T., Goldstein, A., King, P. B., and Weaver, C. E.
1961. The Ouachita System. University of Texas Publication
6120, 401 p. Folk, R. L.
1965. Petrology of sedimentary rocks. Hemphill Publishing Company, Austin, Texas, 182 p.
1973. Evidence for peritidal deposition of Devonian Caballos No- vaculite, Marathon Basin, Texas. American Association of Petroleum Geologists Bulletin, vol. 57, pp. 702-725.
Folk, R. L., and McBride, E. F.
1976. The Caballos Novaculite revisited part I: origin of novac- ulite members. Journal of Sedimentary Petrology, vol. 46, No. 3, pp. 659-669.
Forman, H. P.
1963. Upper Devonian Radiolaria from the Huron member of
the Ohio Shale. Micropaleontology, vol. 9, pp. 267-304.
Fortey, R. A., and Holdsworth, B. K.
1972. The oldest known well-preserved Radiolaria. Bollettino della
Societa Paleontologia Italiana, vol. 10, pp. 35-41. Furutani, H.
1990. Middle Paleozoic radiolarians from Fukuji area, Gifu Pre- fecture, Central Japan. Journal of Earth Sciences Nagoya University, vol. 37, pp. 1-56.
Goodbody, Q. H.
| Silurian Radiolaria from the Cape Phillips Formation, Ca- nadian Arctic Archipelago. Proceedings of the Third North American Paleontological Convention, vol. 1, pp. 211- 216
1986. Wenlock Palaeoscenidiidae and Entactintidae (Radiolaria) from the Cape Phillips Formation of the Canadian Arctic Archipelago. Micropaleontology, vol. 32, pp. 129-157.
Graves, R. W.
1952. Devonian conodonts from the Caballos Novaculite. Journal
of Paleontology, vol. 26, pp. 610-612. Holdsworth, B. K.
1977. Paleozoic Radiolaria: stratigraphic distribution in Atlantic borderlands, in Swain, F. M. [ed.], Stratigraphic micro- paleontology of Atlantic Basin and Borderlands. Elsevier Publishing Co., Amsterdam, pp. 281-285.
Holdsworth, B. K., and Jones, D. L.
1980. Preliminary radiolarian zonation for Late Devonian through
Permian time. Geology, vol. 8, pp. 281-285. Hollande, A., and Enjumet, M.
1960. Cytologie, evolution et systematique des Sphaeroides (Ra-
diolaires). Arch. Mus. Hist. Natur. (7e serie) 7:1-134. International subcommission on Stratigraphic Classification (ISSC)
1976. A Guide to Stratigraphic Classification, Terminology, and
Procedure. John Wiley and Sons, New York, 200 pp.
in press. A Guide to Stratigraphic Classification, Terminology, and Procedure. Second edition, to be published independently by the IUGS.
Ishiga, H., Kito, T., and Imoto, N.
1982. Permian radiolarian biostratigraphy. News Osaka Micro- paleontology, Special volume 5, pp. 17-25.
Jones, D. L., and Murchey, B.
1986. Geologic significance of Paleozoic and Mesozoic Radio- larian Chert. Annual Revue of Earth Science, vol. 14, pp. 455-492.
King, P. B.
1937. Geology of the Marathon region, Texas. U.S. Geological
Survey Professional Paper 187, 148 p. McBride, E. F.
1966. Sedimentary petrology and history of the Haymond For- mation (Pennsylvanian), Marathon Basin, Texas. The University of Texas Bureau of Economic Geology Report of Investigations, No. 57, 101 p., 2 pls.
1978. Olistostrome in the Tesnus Formation (Mississippian— Pennsylvanian), Marathon region, Texas. Geological So- ciety of America Bulletin, vol. 89, pp. 1550-1558.
1989. Stratigraphy and sedimentary history of Pre-Permian Pa- leozoic rocks of the Marathon uplift, in Hatcher, R. D., Jr., Thomas, W. A., and Viele, G. W. [eds.], The Geology of North America, The Appalachian—Ouachita orogen in the United States. Geological Society of America, Boulder, Colorado, vol. F-2, pp. 603-620.
McBride, E. F., and Folk, R. L.
1977. The Caballos Novaculite revisited part II: chert and shale members and synthesis. Journal of Sedimentary Petrology, vol. 47, No. 3, pp. 1261-1286.
McBride, E. F., and Thomson, A.
1970. The Caballos Novaculite, Marathon region, Texas. Geo-
logical Society of America Special Paper 122, 129 p. McGlasson, E. H.
1967. Siluro-Devonian of west Texas and southeastern New Mex-
ico. Tulsa Geological Society Digest, vol. 35, pp. 148-164. Muehlberger, W. R.
1978. Notes on the structural domains of the Marathon region. Permian Basin Section, Society of Economic Paleontolo- gists and Mineralogists, Field Conference Guidebook, No. 78-17, pp. 51-54.
1990. Ouachita orogen, Trans-Pecos Texas. Geological Society of America Abstracts with Programs, vol. 22, No. 2, p. 59.
1991. Folded duplex framing Dagger Flat anticlinorium, Mar- athon Basin, Trans-Pecos Texas. Geological Society of America Abstracts with Programs, vol. 23, No. 4, p. 51.
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 43
Muehlberger, W. R., and Tauvers, P. R.
1989. Marathon fold-thrust belt, west Texas, in Hatcher, R. D., Jr., Thomas, W. A., and Viele, G.W. [eds.], The Geology of North America, The Appalachian—Ouachita orogen in the United States. Geological Society of America, Boulder, Colorado, vol. F-2, pp. 673-680.
Miller, J.
1858. Uber die Thalassiocollen, Polycystinen und Acanthometren des Mittelmeeres. Klg. Akad. Wiss. Berlin. Abh., Jahrg. 1858. pp. 1-62, pls. 1-11.
Nazaroy, B. B.
1975. Radiolaria of the lower-middle Paleozoic of Kazakhstan. Akademiia Nauk SSSR, Geologic Institute, Trudy, vol. 275, pp. 1-203.
1988. Paleozoic Radiolaria. Practical manual of microfauna of
the USSR. Leningrad, Nedra, vol. 2, 232 p. Nazaroy, B. B., and Ormiston, A. R.
1984. Tentative system of Paleozoic Radiolaria, in Petrushevska, M. G., and Stepanjants, S. D. [eds.], Morfologiva Ekolo- giya i Evolyutsiya Radiolarii. Eurorad [V symposium vol- ume, October 15-19, 1984, Akademiia NAUK SSSR Eoologieskiya Instiytut, pp. 64-87, pls. IV and V.
1985. Radiolaria from the Late Paleozoic of the Southern Urals, USSR and West Texas, USA. Micropaleontology, vol. 31, No. 1, pp. 1-54.
1993. New biostratigraphically important Paleozoic Radiolaria of the Soviet Union and North America, in Blueford, J.R., and Murcney, B. [eds.], Radiolaria of Giant and Subgiant Fields in Asia. Micropaleontology Press Special Publica- tion, No. 6, pp. 22-60.
Noble, P. J.
1993a. Biostratigraphy and Depositional History of the Caballos Novaculite and Tesnus Formation, Marathon uplift, west Texas. The University of Texas at Austin, unpublished Ph.D. dissertation, 258 p.
1993b. A cosmopolitan Silurian radiolarian assemblage from Texas, Japan, and Australia: Its utility and potential as a biostratigraphic tool. New England Orogen, Australia, NEO 1993 Symposium Volume, University of New England, Armidale NSW, Australia, pp. 275-281.
Noble, P. J., and Barrick, J. E.
1991. A Silurian radiolarian biozonation for the lower chert and shale member of the Caballos Novaculite, Marathon Basin, west Texas, U.S.A. Universita degli studi de Firenze IN- TERRAD VI Abstracts, p. 67.
Perner, J.
1899. Etudes sur les graptolites de Boheme. Raimund Gerhard,
Leipzig, Prague, parts 1-3, 94 p., pls. 1-17. Pessagno, E. A., Jr.
1971. Jurassic and Cretaceous Hagiastridae from the Blake-Ba- hama Basin (Site 5A, JOIDES Leg 1) and the Great Valley Sequence, California Coast Ranges. Bulletins of American Paleontology, vol. 60, No. 264, pp. 1-80.
1973. Upper Cretaceous Spumellariina from the Great Valley Sequence, California Coast Ranges. Bulletins of American Paleontology, vol. 63, No. 276, 102 pp.
1977. Radiolaria in Mesozoic Stratigraphy, in Ramsay, A. T. S. [ed.], Oceanic Micropaleontology. Ch. 9, Academic Press, London, New York, San Francisco, pp. 913-950.
Pessagno, E. A., Jr., and Newport, R. L.
1972. A technique for extracting Radiolaria from radiolarian
cherts. Micropaleontology, vol. 18, No. 2, pp. 231-234.
Pessagno, E. A., Jr., Blome, C. D., and Longoria, J. F.
1984. A revised radiolarian zonation for the Upper Jurassic of western North America. Bulletins of American Paleontol- ogy, vol. 87, No. 320, 51 p.
Petrusheyskaya, M. G.
1971. On the natural system of polycystine Radiolaria (Class Sarcodina). 11 Planktonic Conference Roma 1970, Pro- ceedings, pp. 981-992.
Renz, G. W.
1988. Silurian Radiolaria of the genus Ceratoikiscum from the Canadian Arctic. Micropaleontology, vol. 34, no. 3, pp. 260-267.
1990. Late Ordovician (Caradocian) radiolarians from Nevada. Micropaleontology, vol. 36, no. 4, pp. 367-377.
Riedel, W. R.
1967. Subclass Radiolaria, in Harland, W. B., et al. [eds.], The Fossil Record. Geological Society of London, pp. 291-298.
1971. Systematic classification of polycystine Radiolaria, in Fun- nel, B., and Riedel, W. R., Micropaleontology of the Oceans. Cambridge University Press, pp. 649-661.
1978. Systems of morphologic descriptors in paleontology. Jour- nal of Paleontology, vol. 52, No. 1, pp. 1-7.
Riedel, W. R., and Foreman, H. P.
1961. Type specimens of North American Paleozoic Radiolaria.
Journal of Paleontology, vol. 35, No. 3, pp. 628-635. Ross, C. A.
1979. Late Paleozoic collision of North and South America. Ge-
ology, vol. 7, pp. 41-44. Rist, D.
1892. Beitrage zur Kenntniss der fossilen Radiolarien aus Ges- teinen des Trias und der Palaeozoischen Schichten. Pa- laeontographica, vol. 38, pp. 107-200.
Scotese, C. R., and McKerrow, W. S.
1990. Revised world maps and introduction, in McKerrow and Scotese [eds.], Palaeozoic Palaeogeography and Biogeog- raphy. Geological Society Memoir, No. 12, London, En- gland, pp. 1-21.
Thomson, A.
1964. Genesis and bathymetric significance of the Caballos No- vaculite, Marathon region, Texas. Permian Basin Section, Society of Economic Paleontologists and Mineralogists, Field Trip Guidebook 64-9, pp. 12-16.
Thomson A., and McBride, E. F.
1964. Summary of the geologic history of the Marathon geosyn- cline. Permian Basin Section, Society of Economic Pale- ontologists and Mineralogists, Field Trip Symposium and Guidebook, No. 64-9, pp. 78-85.
Thomson, A., and Thomasson, M. R.
1969. Sedimentology of the Dimple Limestone, in McBride, E. F. [ed.], Stratigraphy, sedimentary structures, and origin of flysch and pre-flysch rocks, Marathon Basin, Texas. Dallas Geological Society Guidebook, pp. 78-85.
Wakamatsu, H., Sugiyama, K., and Furutani, H.
1990. Silurian and Devonian radiolarians from the Kurosegawa Tectonic zone, Southwest Japan. Journal of Earth Sciences Nagoya University, vol. 37, pp. 157-192.
Won, M. Z.
1983. Radiolarien aus dem Unterkarbon des Rheinischen Schie- fergebirges (Deutschland). Palaeontographica, Abt. A, vol. 182, pp. 116-175.
44
BULLETIN 345
EXPLANATION OF PLATE 1
Scanning electron micrographs of Rotasphaeracea (Radiolaria) from the Caballos Novaculite, Marathon Basin,
west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure 12%
Sete cassa ?, Nazarov and Ormiston, 1984 ........ : 2b SS: bhateiex snotty apate eae ala es Sa ee
. Sample 213c, East Bourland Mountain, scale bar = 35i um. . Sample 213c, East Bourland Mountain, scale bar = 50 um.
We Secuicniiagia Solara WDEWASPECIES epee eee ee eee Sooo overeat ete GIS a « Ray A
3. Sample 217, East Bourland Mountain scale bar = 35 um.
4. Sample 323c, Payne Hills, scale bar = 50 um.
5, 6. Sample 215c, East Bourland Mountain, scale bar = 50 um. 7. Holotype (USNM 466289), sample 325c, Payne Hills, scale bar = 50 um. 8. Sample 326c, Payne Hills, scale bar = 50 um.
. Secuicollacta foliaspinella, new species sign Bais couches SG ys, Soins lg SUPER Le EST heise or ote ese eee
9. Sample 219, East Bourland Mountain, ain oe = 50 um. 10. Holotype (USNM 466286), sample 326, Payne Hills, scale bar = 50 um. 11, 12. Sample 325c, Payne Hills, scale bar = 35 um.
. Secuicollacta sp. PE SOA iene ae ec teacdeeircdonoccbboodanoceocace
13. Sample 326c, Bayi Hills, scale bar = 35 um. 14. Sample 325c, Payne Hills, scale bar = 50 um.
. Secuicollacta sp. A. : : ae ety: PE nn one oa nao dor ck ac
Sample 324c, Payne Hills, scale fan = 50 um.
us ecuicollactas(?) platy spina sNeWwsSPeCleS': <aran..<isy-v aes 5 2 Ss evensia ais oe oes cae ee On ee ee ee
Holotype (USNM 466287), sample 219, East Bourand Mountain, vei eee = = 50 um.
+ Rotasphaerainisda:, new Species? 2s ga8 3 Sacwlee a's o steGacieretass ea EE Ee Oe EE ee
17. Holotype (USNM 466293), sample 216, East Bourland Monnet scale bar = 35 um. 18. Sample 325c, Payne Hills, scale bar = 35 um.
PLATE |
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE
EXPLANATION OF PLATE 2
Scanning electron micrographs of Rotasphaeracea (Radiolaria) from the Caballos Novaculite, Marathon Basin,
west Texas.
Figure
Is.
13-16, 19, 20.
17, 18.
The scale given after each figure corresponds to the scale bar in the lower right.
Rotasphaera marathonensis, new species ......... 2.2... ee tees 1. Holotype (USNM 466290), sample 326c, Payne Hills, scale bar = 50 um. 2, 3. Paratypes (TMM 1849TX3), sample 325c, Payne Hills, scale bar = 50 um. 4. Sample 326c, Payne Hills, scale bar = 50 um.
UPR OLASPAGCVAiTODEFISOFUMM NEW 2SDECIES ©. ercinys oie cioss ores) 2 oie cic nas sete Sealers o aie eval sb otave a, Sieveveutue grb .es
5. Holotype (USNM 466295), from coma 216c, East Bourland Mountain, scale bar = 50 um. 6. From sample 326c, Payne Hills, scale bar = 5O um.
Se Rotasphaeralbeckwithensisanew SPEClES sae nrc cir ete so aces at cfeyiene ee) ins the iets oi sisie ee ere ee
7, 10. Sample 217, East Bourland Mountain, scale bar = 50 um. 8. Holotype (USNM 466291), sample 217, East Bourland Mountain, scale bar = 50 um. 9. Sample 324c, Payne Hills, scale bar = 50 um. 11. Sample 325c, Payne Hills, scale bar = 50 um. 12. Sample 327c, Payne Hills, scale bar = 50 um. OLAS PRAChAIGUAAIala me WASDECIES ire ecient a eee cle aie oe Renee eee 13-16. Paratypes (TMM 1844TX2), from sample 219, East Bourland Mountain, scale ie = 35 um. 13, 14 and 15, are rotated views of two specimens. 19. Holotype (USNM 466294), from sample 219, East Bourland Mountain, scale bar = 50 um. 20. From sample 327c, Payne Hills, scale bar = 50 um. Rotaspahera delicata, new species...........................2... 17. Holotype (USNM 466292), eanole 325, Payne Hills, scale bare 50) um. 18. Sample 219, East Bourland Mountain, scale bar = 50 um.
Page 21
i) Ne
46 BULLETIN 345
EXPLANATION OF PLATE 3
Scanning electron micrographs of Spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure Page 1=—4; Pseudorotasphaera'(?) robustispina, NEw SPCCIES « « =). :)-0.6 6 6 iyo ses sere ine 2 res © ee etre eI) eel ole ee ene eee 1, 2, 4. Paratypes (TMM 1849TX4), sample 325Sc, Payne Hills, scale bar = SO um. 3. Holotype (USNM 466299), sample 325c, Payne Hills, scale bar = 50 um. 5-7. Pseudorotasphaera hispida; new SPECIES; «...< 0. <0 cee cree 5 2 esse as wi ew So ess al © © Sew eln oil eee eee ee 25 5. Holotype (USNM 466296), sample 3256, pane Hills, scale bar = 50 um. 6. Sample 323c, Payne Hills, scale bar = SO um. 7. Sample 396c, Wood Hollow, scale bar = 50 um. Specimen 7 has poor preservation of secondary spines. 8-10. Pseudorotasphaera lanceolata, new species : REL tere ae o's wie ac 4¥ie asa aed cc alegre a bata ah den are ee a Or 26 8, 10. Sample 395c, Wood Hollow, scale bar = 50 um. 9. Holotype (USNM 466298), sample 395c, Wood Hollow, scale bar = 50 um. 11, 12. Pseudorotasphaera (?) rotunda, new species Rh ee oie eC CCE a layar4 904 & ce ayallse ss.anejaveeey sere oleae eee 27 11. Holotype (USNM 466300), sample 326c, Payne Hills, pele bar = 50 um. 12. Sample 325c, Payne Hills, scale bar = 50 um. 13-18. Pseudorotasphaera communa, new species... . =e wg wtehe i vaca ce Yaya'e bays (e ayoueegnene 0g (ese exatays Sherrer ete 26 13. Sample 216c, East Bourland Mountain, scale bar = 50 um. 14. Sample 395c, scale bar = 50 um. 15, 16. Rotated views of same specimen, sample 326c, Payne Hills, scale bar = 50 um. 17. Paratype (TMM 1844TX3), sample 219, East Bourland Mountain, scale bar = 50 um. 18. Holotype (USNM 466297), sample 219, East Bourland Mountain, scale bar = 50 um.
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106
\O w Ss 2 =) a fe) Ss
AMERICAN PALEC
BULLETINS
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE
EXPLANATION OF PLATE 4
47
Scanning electron micrographs of Spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure
NZ
10, 11.
15-17.
18, 19.
. Pseudorotasphaera hispida, new species....... . Pseudorotasphaera (?) robustispina, new species .......... . Pseudorotasphaera sp. dio pie COD DE OS ORS Toe . Palaeoactinosphaera (?) octaspina, new species ...........
. Palaeoactinosphaera barricki, new species
. Palaeoactinosphaera asymmetrica, new species .......
Pseudorotasphaera sp. ...... FP AO CS RORY Oe ONeill OL 0 CLCUR ERC ee ER RRR ac Pee ie
Sample 386, Rock House Gant ieraement showing maternal structure. Arrow points to hollow ai (omnes pan) oe to primary spine. Thinner solid rod (secondar bar) connects to cortex, but not to a primary spine. 1. Scale bar = 12 um. 2. Scale bar = 25 um.
Sample 395c, Wood Hollow. Fragments Bhowingss: spinose nature of cortex. 3. Scale bar = 35 um. 4. Scale bar = 50 um. Sample 325c, Payne Hills, scale bar = 35 um. Broken specimen with chalcedony infilling which obscures internal structure.
Sample 395c, Wood Hollow, ecale bar = 50 um. Broken specimen showing internal structure.
Holotype (USNM 466214), sample 223, East Bourland Mountain, scale bar = 50 um. 8. Holotype (USNM 466307), sample 325c, payne Hills, scale bar = 50 um. 9. Sample 325c, Payne Hills, scale bar = 35 um. Note prominent collar grooves along spines. Base of grooves penetrate cortical shell at collar pores. Palaeoactinosphaera elegantissima, new species............. 10. Sample 326c, Payne Hills, scale bar = 50 um. 11. Holotype (USNM 466309), sample 326c, Payne Hills, scale bar = 50 um.
12. Paratype (TMM 1842TX1), from sample 215c, East Bourland Mountain scale bar = 50 um. 13. Holotype (USNM 466306), from sample 322c, Payne Hills, scale bar = 50 um.
14. Paratype (TMM 1841TX2), from sample 214, East Bourland Mountain, scale bar = 50 um. Palaeoactinosphaera antica, new species .
15. From sample 223, Payne Hills, scale ba = 50 um. 16. From sample 214, East Bourland Mountain, scale bar = 35 um.
17. Holotype (USNM 466305), from sample 214, East Bourland Mountain, scale bar = 35 um. Stylactinosphaera prima, new species ........ :
18. Holotype (USNM 466310), sample 322c, pane Hills, Fale bare ~ - 88 um.
19. Sample 322c, Payne Hills, scale bar = 88 um.
Page 40
35
34
33
36
48 BULLETIN 345
EXPLANATION OF PLATE 5
Scanning electron micrographs of Spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure Page lee Spumellariansindetasp Auer esate eee ere ae Sexes OR rae Li cantata Sco te tS one 39 Sample 328, Payne Hills, scale bare 88 um. 2-4. Stylosphaera (?) magnaspina, new species ..... hw vaste cdc dcayray'ns Seas tfove fe beuetistey sso ox IARI Ove aie CEE OE OCT eee 38 Sample 328, Payne Hills, scale bar = 88 um. 556: Good bodium Spica cine ociscreieie oasis statics Sais Clee PLT OE ee ee ee rsacn og OU neo adou osacqccooc 37 Sample 215c, East Bourand Manian scale pane = 35 um. mei oldsworthum:sps nce ere coe ree cee Ee Se a re nr enone dneoadadanbbatrcaccnce Si/ Sample 326c, Payne Hills, scale bar = 50 um. S59 se Spumellananindetasps Daeeerenter erent tee ee cia rar ae Samet eee oc angus asa vet eo role touetoh 3 Shale a ten 39
8. Sample 325c, Payne Hills, scale bar = 50 um. 9. Sample 326c, Payne Hills, scale bar = 50 um.
10. Cenosphaera hexagonalis Aberdeen, 1940 wana ate ‘ Sabasecctestemtovere oS. avie eas a) be ea eahdpets iee/eke ahs ae eee ee 38 Sample 215c, East Bourland Mountain, scale bar = 50 um. 11; 12!, Palaeoactinosphaera (?) crucispina,, new Species; ...2..... «2420 see sees 2 ee ee eee eee Gene eee eee 34
11. Holotype (USNM 466308), sample 322c, Bayne Hills, asi nae = 88 um. 12. Sample 322c, Payne Hills. Broken specimen showing internal structure. Note bladed primary bars, scale bar =
50 um. 13, 14. Undescribed Spumellarian ctanoshalcte <o tore eae jag ava, oyahd.yfehafe prob dp enched ormlete pes eo ee 41 Sample 223, East Bourland Mountain, scale bar = 50 um. 15,17, 18. Fusalfanus osobudaniensis Furutani, 1990 . Sou eaeotman ded; ba She a,atece ana igo oietiae eis eneneye ee ee 30
15, 17. From sample 325c, Payne Hills, scale bar = 50 p um. 18. From sample 213c, East Bourland Mountain, scale bar = 50 um. 16,, Tranihella:sp: Aye © oicocis:dis.caccies ns! Coagatssove eon + se aus valerate “auclevahs shasse [Lee etone PISUR Gece tiers CoRR Re aS Ieee 30 Sample 327c, Payne Hills, scale bar = 50 um. iNet delicate remnants of delicate outer cortical shell.
S
VOLUME
AMERICAN PALEONTOLOGY,
BULLETINS OF
BULLETINS OF AMERICAN P. 3Y, VOLUME 106 PLATE 6
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 49
EXPLANATION OF PLATE 6
Scanning electron micrographs of Spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure Page IPRA OrIERGOL UL) (2) (KIM Ea NEW/SPECLES «nin s-cyersisvoe we 2 2c eens spaasts jays. ae ev svace Sp'ererayspape cue mie ereb Ag ASmpel » ousebeys- # nica ania Siareteveuaneverairwe le esyenoytre 31 1. Holotype (USNM 466302), sample 325c, Payne Hills, scale bar = 50 um. 4. Sample 327c, Payne Hills, scale bar = 50 um. Deo ee OTIUNGOLULLG (VANES PENG eMC WASDECIES) ors .icyoicseic he ote ov ei lcte oss teva cncieu= isi. eeie aie) euere h102/e-eie, 4 svese-iojeiesousieyeseie #ieseieie.e te e.r crtiele ope Sinai 31 2. Holotype (USNM 466303), sample 8802, Monument Creek, scale bar = 50 um. 3. Sample 8802, Monument Creek, scale bar = 50 um.
SEZ AUF ADPOLUSISD Gallons PUMOSU Sia er eater ON eae ees teal aire era cee see wa eNO MO CEA eee eye SeI ee resc ee ee senene ees APS Attra = Sample 219, East Bourland Mountain, scale bar = 50 um. Note tapered spines are shorter than Z. spinosus. CaeZ AdrappOlus SpinOSUSIEUTUTANTs 99 Owe aces celery recede ere eereres oat acos Tee) vera or exeler coed eStore sual Lote Pe lee Tiassisuske Gvcre te craiais Oheleke ate 32 Sample 326, Payne Hills, scale bar = 50 um. Ao mee Car ApDOLUS UAAVIS NEW; SPECIES is... roe eI aie ese ee ee OIE GEOG fe + Sieh Peele a leisuaye #4 s) sere BPN SOlaE Sse Gees as Sepa ties 32
7. Paratype (TMM 1853TX1), sample 330, Payne Hills, scale bar = 50 um. 8. Holotype (USNM 466304), sample 330, Payne Hills, scale bar = 50 um.
©), ZORA WAITS Goh, ae a cing a games oe SUG Dist poe AES See SEO E Deo NU Aman SRA Eee ema at Em menine a isn coe rene nnoae 32 Sample 326c, Payne Hills, scale bar = 88 um. Mtl 2S eZ AAD POLS LCITEES SUIT ATA 19.9 aye re peereryy aris one eee vce er sees ee aeaee steel svete 22) ease sic seis) eyeietereceysenstsuerans ene erevea aiaievavaraToueieaese ere 32 Sample 223, East Bourland Mountain, scale bar = 50 um. lie Zadrappolusisp yall gtenurspRurutanis 199 Ol rey vce vere vas ethene ocr eh cue ever ev Pee ueD Peete ie VN EFol TENE evcnsteteTaverare Tre eee 32 Sample 324c, Payne Hills, scale bar = 50 um. 4 —l6neZadrappolus:yoshikiensissurutanis 199 Oy acy -cc se eee e cteeae 66 6 Seer eo VO IAG SEI aliens) fee edo e eee eters « Be cine dee eels 32
14, 15. Sample 325c, Payne Hills, scale bar = 50 um. 16. Sample 327c, Payne Hills, scale bar = 50 um.
BULLETIN 345
EXPLANATION OF PLATE 7
Scanning electron micrographs of Spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. The scale given after each figure corresponds to the scale bar in the lower left.
Figure
1s.
13-15.
16-20.
Page Praespongocoelia (Spongocoelia) parva Furutani, 1990 ...... Wave,a.6j0i0 4 oraod acete wid S1sla 8,2.) Sa SIN Ge eae Te Se ae ee eee 38 1. Sample 215c, East Bourland Mountain, scale bar = 18, um. 2, 3. Sample 215c, East Bourland Mountain, scale bar = 50 um. 4. Sample 077, Payne Hills, scale bar = 88 um. ., Bipylospongia\rudosa, New SPECIES: ©. 2-05 5155-252 sie e ciersie wis sore orgie © ore eee le 4 Cie S15) 9/88 ee LS Slee eae nIe is ORCL a Sera 37 6, 7, 9. Paratype (TMM 1841TX3), sample 214, iene Bourland Monnearn scale bar = 50 um. 8. Holotype (USNM 466311), sample 214, East Bourland Mountain, scale bar = 50 um. b, PPRA@SPONBOCOELIA:SDs 2.5. <:0!.5.5 coc seins sycvare os 8 ss enero reid re SrH aS vad 4 a1w'd 20S EELS sere Shee Sv aIaET EL) DRE FOES PSIG TOCSY CG eee 40 Sample 077, Payne Hills, ecale re = = 50 um. Fragment enone spongy cortical wall. . Praespongocoelia fusiforma; NEW. SPCCIES :. :6: 5 2.6.6.0: « sods 2 store wee Gl avsinie are Fisa,s ORRIN Piche eels SOMOS CORO Ee eR eee 38 11. Holotype (USNM 466312), sample 213c, East Bourland Mountain, scale bar = 50 um. 12. Paratype (TMM 1855TX1), sample 396c, Wood Hollow, scale bar = 50 um. Pseudospongoprunum (?)| tataverst, NEW SPECIES)... :s..:< <cccecc are coo are ara) «aye 01s «aia wre) e)elelojole) eyere eteye)o] olelalairelel sia eie eros) aie leet etetee tei ceteeenene 28 13, 14. Sample 882, Monument Creek. Eaustonal a6. Solan sections showing multiple concentric spongy layering, scale bar = 50 um. 15. Holotype (USNM 466301), sample 882, Monument Creek, scale bar = 50 um. Devoniglansus unicus Wakamatsu et a/., 1990....... - ae ees saa net aad ava, audiwievays. a, aaysatl Os, alae SnyaEe eRe ee 28
16. Sample 330, Payne Hills, scale bar = 50 um. 17, 19, 20. Sample 330, Payne Hills. Same specimen, scale bar = 50 um (figs. 17 and 19), 18 um (fig. 20).
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106 PLATE 8
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE
EXPLANATION OF PLATE 8
Transmitted light micrographs of Rotasphaeracea, all scale bars = 50 um.
a
B36:
4,5.
LOS We
. Rotasphaera marathonensis, new species ..... 2.6... 62 eee x Sample 328, Payne Hills, note open pore network and fine seeonihiay spines. . Sample 326c, Payne Hills. Seeuicelincte SOlara MEWESDECIES Sis ie Goth oO Cnn aril ACEO oe ee ER ee ace ern tenn Ao DS 3. Sample 326c, Payne Hills. Note Poaephnenia structure Scitiy 6 primary rode 6. Sample 326c, Payne Hills. Rotasphaera beckwithensis, new species . BAe Oe ORE TU OO a Leno EEE DIRT a Orae aan OOO
4. Sample 326c, Payne Hills. Note rotasphaerid structure with 6r primary fode aul degree Bitentine of primary spine Spases!
5. Sample 326c, Payne Hills. Focal plane is on cortical shell to illustrate pore structure.
belseudorotasphacrailanceolata. Mew. SPeCleS:s «,. <a 4.0. sevt 5 eve uns tat ee Ete VSS ee ans ORI ee eee eee ater ene ste
Sample 395c, Wood Hollow. Note long thick- bladed spines. Veorical Shells 1S fee cated Sem that of P. communa.
2. Pseudorotasphaera communa, new species
8. Sample 213c, East Bourland Mountain. Focal plane on cortical ll Ehomineto pore structure. a Sample 213c, East Bourland Mountain. Reversed side of specimen in fig. 8 showing internal structure. . Sample 213c, East Bourland Mountain. Enlargement of fig. 9 showing close-up of internal structure. poe aise sp. Sample 395c, Wood Hollow. ements souine Garena structure.
51
Page
41
n i)
BULLETIN 345
EXPLANATION OF PLATE 9
Transmitted micrographs of non rotasphaerid spumellaria (Radiolaria) from the Caballos Novaculite, Marathon Basin, west Texas. Each scale bar = 50 um.
Figure iV.
tN
Page
Fusalfanus osobudaniensis Furutani, 1990 5S bso ae aye salecasrtenfaySkox SSR cai’ co, Seo) acdiis «aha cee Silay d0SSSpS Se SPEVRISES a sepa ane eer 30 Sample 325c, East Bourland Mountain. Shell filled si picreteaiine quartz which obscures internal structure. Note spongy wall structure.
. Cenosphaera hexagonalis Aberdeen, 1940....... soe si fave anes les See saoi) seust'yst exepevahala quads MSL aS ETOP ee ee eee 38 Sample 326c, Payne Hills.
. Palaeoactinosphaera (?) octaspina, new species ....... erin : , : ssid prayer’ Shsuaysdeccuss 42 oC eee ee eae 35 Sample 223, Payne Hills.
. Oriundogutta (?) varispina, new species............ en eee «jad aaiahanovaraltey cvSyos tye Sha Syshelees “6 Gib ye yates aoe eRe eae eee 31 Sample 435c, McKnight Ranch.
. Palaeoactinosphaera (?) crucispina, new species... .. selesacurye era cansgaiatege : sista © apace SPS canbe) ates veheree ab ale de OLA TORR eee 34 Sample 322c, Payne Hills.
. Oriundogutta spp. a syste yo rages eee : : ; Ryo Beco ae Rae oa a, Hebi taysysne eee ”?
Sample 330, Payne Hills. Zadrappolus lunaris, new species : She : ssayarshe anayehec tape etleret otal Sees 32 Sample 330, Payne Hills.
. Zadrappolus spinosus Furutani, 1990 : Ree con Gne ieoee oat Cee 32
Sample 223, East Bourland Mountain.
. Zadrappolus sp. : «2 er aigieiels erate eae 32
Sample 223, East Bourland Mountain.
BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 106 PLATE 9
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 53
INDEX
Note: Page numbers are in light face; plate numbers are in bold face type.
REGERACENAEN GEMOSPRACIA® sevwave ceo sa pareyaawecsacese not eee eo Acanthosphaera macroacantha amoenitas, Secuicollacta .............. FEINIGQs Ph AIQCOACHINOSPNGENA. <5..5..ccc0ccesceecusse-es0ee0s PNSTROCHICACUITIINAC. coece dress oc cicraacoc cues cocawawenncsseecrertoestcversenre asymmetrica, PalaeoactinOsphaerda .............6.00.0000% 4, 13, 34, 36 PMUISERaliaweececc eee: Me ccscecasac tie seedaeytaueeu se ecmterecerncocsnaadeveeesteate 6 AKAN ASENISISMUTCIIOCNLACLINIG, sete v.c2-s- noses sseecses stead acess eerces 30 barricki, Palaeoactinosphaera ..... ee 45135345 35 EESIDOV.OSUS: sl CXASEVIUS. tec socck ss oulsewsouecne ss sesaceuaseceoseseroeeeseceee 20 BECK WIth ELIS prac cnn cer ccc cas nesaeeantwape aacsevenacbeareesonres 20, 39, 40 beckwithensis, Rotasphaera .............00.00c00005 2, 8, 13, 14, 20, 21 PB CLOGELIGISP ID Geta tees acto rte cers Soe ses eee ae oss ee CSET AEE as TRE 14 BOLO! Re ener oa Reco cote ae Ree eo Dea aa a ae aT ea aas 14 SIV OSPOMNSIQINUAOS Ca cee eee ce cciecoe re aes dee eee eaceee caren ce TNS S37 IBID YLOSDONLI Aims cen ease sec Sach anaes eee serene noe eee eee dhs sls VE ei7/ aballosiNovaculite se-2.-22- 22-2 --seoesceeesceeee see 7-9, 11, 14, 39-41 ARE LO Ler eset -orecersecnseess pha enone See crocios soos LOCA ETM eee 14 SAM PIEYAESCHIPtONSe cesese-.ceove seatenes cen cis ccevesseeenetomeseers 39441 GanadianvArchipelago: <ie.. feccncseeecs.ctecsscesccssmacsanenne ene 6, 14, 19 TaGiOlanantaxaOM vec. .c2escssaecavese sue dose crocs coseere se 33537539 GOSS? 1S CCULCON ACI. aoa. nance ne easedcecetneetcaescesecresneseeeeas 123 CASS S CCUICOMACLON ve. e200 nance se Peed eee oreo eee eee 14, 19, 22, 23 (GEN OSDHGErAKADETACENAC: mete rec wee ares ener eee ee ee 38 Cenosphaera hexagonalis ..............06..000006+- 5, 9, 14, 17, 38, 39 Cenosphaera plutonis CGENOSDNACT AN acto oes eonene coe eT Chal CeGdOnyAreecrsct ccnceres cer ecstes ees eedeeantbccess sen cette OllaTsPTOOVES ee one oceores svc cecees socmeeeut os ove ceecee scree BOM ATEDOTES eto eee scat ease sie ek scaubaste ccebenserswors os ssearaeeees CONOGONUS) neces parcwewecee soswace coreuieeascneciess seatone saeeeces (GONIGYNLT A) Be fesewons savesess seedotievscaausieew sung seeawsw es seestdeseestesetes (CO RTGLT TIAL, Ware ne eee an saa nae eee AEA Beer eaar ic eanccenbaeacead COLA Sipereconsewescacireca sce atavan cea eseaeacvie sows Dove sve aeueatessateetee seowesee Cornwallis Island crucispina, Palaeoactinosphaera (2) ..........0..00.00-00005 55/9: 113; 35 Dapper blatvAntichinOmuUm wess.-c. + 2sesessee-coeectsccsscaseeeteees-toe ce) DAD SILOAUSLODIIQUICOSLALUS st as ee eee cence eee 14 DADSILOAUSHDIAECIDUULS GE Neen ete ee reece eee nee 14 DA DSTLOGUSISDATSUSim er tecnc deen cdsnere neon ence eee eae delicata, Rotasphaera ... Devonian, Late ........ Devonian, Middle .... b IDEN OVILGIANSUS Mens eae erent 1 W385 AAS NS MGR 28529 637) Devoniglansus unicus—Pseudospongoprunum tauversi Interval FLED Ao) eS ROO CRE ERRESCCCE EEC OE ORE CERRO CER ECE EPR 14 DDeVONIIANSUS UNICUS. .......2-.2..00000 75 USS 4 SUS 1 6528529937 Dim pleweumMeEstom gure ee saree eke Cece ose eee aero eens ee ae 7 East Bourland Mountain typevlocalitiesiat 2.4.2.2 s25 2c. 20, 21, 22, 24, 26, 34, 37, 38 locality GescriptiOminerecaesetes sa cers sare ne seat eee wees costes ca tecece 41 echinatum:.?Palaeoephippiurme? Che = 2ooseccc-c-cce-c--0ec-doseeeeeeeese 23 elegantissima, Palaeoactinosphaera ...................-- 4, 13, 34, 35 ESNITACLINOSDNRACN A a cwccin Senco ne Meee ae Oe ee aoe ens 16, 33, 36
LAMINALUIN NA GCOSCENIGIUIM presences neers cate tene eon ene eee 37 Holiaspinell aS CCUICOLIAGLA. s2eesenanencesete.sseceasceore renee 123524 Buk jicAneal occa. a. descsnenescts cecos oileaes dea tdwocveusss sso eee eee 15-17
radiolanianutaxavinOMmy <.2.-2c--.ec0s-ee-aseoseeeees =e 23; 25; 31,32,.38 Fusalfanus osobudaniensis Assemblage ..........................20-- 16 Fusalfanus osobudantensis ............060.002-000++ 5, 913 6530N311 usalfanuspeencesccercces ater etcenarsercerecertesese ee 5, 9, 16, 17, 30, 31 [USI{ONIMGPIAESPONLOCOEIIO maeeeeeneceoeee cote e ease eee eee 7, 16, 38 GifullPrefecture ma. sccrcsessace sone seec anc so: dat wec ee eee enna ote eee 15, 16 Goodbodium S44. 1S Sa6NS7, Haplentactintidaey...<s2e- 0c niece scsscsscovecntecs tee tocen seeeeeceee en 19523, MaymondlFormation! 222.cc<2ccc-csescesove toe so-ceaseoe tee see--e-se essences 7 Helioentactiniaibakanasensis, .2.c2cc. «<ceeeee- 222s 00-222 -e- eee see see 30 hexagonalis,sGenOspnaesra) 2-cssc2.ccesecsee-ae-se 559) 1459175385,39 HexastylusiDGSIDOrOSUS Wee iice sce seen dececesteeseeace se eteee cee eee 20 hispida, Pseudorotasphaera .....................2+. 3, 4, 13, 25, 26, 27 hispidawStylosphaena..<scse-c22 2: 2228 eee oor ee e 39 FVOLASWorthinrrus pi A sese see essa se eee ee 55317) FT OLAS WOTERUIN ded. wacscxcsessenede sca sedccugan sO ae eter OO hy Sii/ horridasS ecuicollactaispych Sa -nsesteeeerrce see ceec eee eee 24 hydrofluoric’acid|etching) s:..2e-2-<2e-<c-ceee+-t2ne= see -eeseeeeeeeeseeeses 11
Ichinotani Valley, Japan WNANISUELG: Zciesceccscssoee se eeseenese te hone eee Inaniputtidae®\..25.222.22.ccns ess scondasrevoueseecs
Inanthella macroacantha ...
Tnanthella:sp Ayr sceazssticsctes couost cane set ence terrae eee ImanthellaitanrGnculicd p-seesscsscercser mee siee esas cee ee eee eee DET TAL De ee Pr te ne OO De Se Er ee eee Tc
kingi, Oriundogutta (?) ...
Kockelella absidata .............. Kurosegawa Tectonic Zone) <2:1cccverecncu-ececeons seeeese sseeceeree ease 15 radiolarianitaxal from =--¢--cssee-esee se aesea see eeeee ee 235 285295159) lanceolata, Pseudorotasphaera ................0..00.- 0002002 3, 8, 13, 26 Tlandoveriam sth. Sioctccc. cc deerce eee 14, 16 Mowest-Occurrence:Zones defined! -iesssessste se scesseetaeeee es cteeenee 12 Mud lovin geese 8 os ee oes eee 13, 14, 16 NUNGTIS: PZ GAAP DOLUS eneeen eneee een este cece eee 6, 7, 14, 32, 33 macroacantha: ACanthosphacra Wre.ececetnes sae c cance ee eee sore 31 macroacantha, Inanihella 714530531 magnaspina, Stylosphaera (2) ........2.ccccce00ececeeeeee eee 5; 135 39 Marathon Basin® sie. se. eiecccccec sons .ctwess cessor covact ses untesieeseesee 6, 22 Marathon uplift PEOLORY ies. ixsee Ses ssectenevs isusee sot eins ove seat nate vance eee eeeees etna 6-9 StructuralidOmains® Werecc. te ccccre een ee car ee ee eae eeen 7,8 radiolarian zones of ................. se GUS aS TSUN Seas TEE oS 13, 14 marathonensis, Rotasphaera ee 28, 135 19820921027 Marawvallasilcimestone’ ssece---osescececcsseececacscoec comers rareeee reece aaa 8 McKnight,
localityidescription) fesse soceceset arene eee aera 40
54 BULLETIN 345
IMUSSISSIPPlAM essere cess ase ceee see ace oreo cc ene-c rece rer seee cere ss= a= 6,8 Monumenti@ree kis srets resect aee eee sane sanmesone eee eeeees 9,14 localityideScription! ec.----2--cesscesesesere -eree er erase == namo 40 type localities at THLONPNOSPECIES Meeseee eee ees eneceseceeteesseesees seae = seamen NOVACUIIte ere eeeeee nee serra soa eee bee secre en cee ctor senate es aeenenes 8,9 MUR OLAS PNGEN Gia eee e secon ee an cans mses seen seer rem see ee = 1, 20, 21 octaspina, Palaeoactinosphaera (?) ........:.01002000++ 4,9, 13, 14, 36 @rdovician-wlcate) peecspesseeeeceeacce ene seceereen eens nese eacetess 8, 18, 19 Oriundogutta (2) Kingt .........02c00ec0eeereeee . 6, 13, 14, 31 Oriundogutta (?) varispina 6, 9, 14, 31 OViuindo gutta raMipiCcaNnsi 22.222 -c see se-es--eemcmsseaesece sere see-ea-o n= 31 Oriundogutta prccsseereea eee 6, 9, 13, 30, 31 @sobudani Walley; Japan’ wercsscesecseseeseeeeere se seeee eter eeeteceeerses 16 osobudaniensis, Fusalfanus ........0.c00c0ee00e002 5.9) 1316: 30531 @uachitatorogenicibelt, Casec.-seecenss-econ=ssenseaecen-seteru see -ceeeee mea: 6 Ozarkodina e0steinhornensis ? .......-.--.--ceecoecoesretanssescescuseess 14 PalaecoactinommmidSy xccceccseoe-ee--see sass beens seeesee ence 14, 33 Palaeoactinosphaera (?) asymmetrica Lowest-Occurrence Zone .... Bl TE Be ee os cau sn Sons cats uu ne FSaeSER OSS COU Naso See 13 Palaeoactinosphaera (?) CruciSPIN@ ........0.-02-00e022e 820 559) 13535: Palaeoactinosphaera (?) Octaspina ........-.+-++- 4, 9, 13, 14, 36, 36 PalaeoactinOsphaera ANCA ..........0..000-00ee ence eeeees 4, 33, 34, 36 Palaeoactinosphaera asymmetrica ce Palaeoactinosphaera barricki ...........0.-00020002-00000 Palaeoactinosphaera elegantissiM@ ..........--+.--++++++- 4, 13, 34, 35 IPGIGCOACLINOSPRACIQ, 22.222 ce2ece-22-cae=- e257 4, 5, 6, 33, 34, 35 , 36 Palacoactinosphaendae) ces--.-s2-esse-c-ses0senns-sseecessensees 18, 33, 36 Palaeoephippium ? cf. CCHiNQtu ........00cc0ceeeeeeeeceeeeeeen teense 23 PalacOSCenidiidae® sce ssccse-cucesecssoss=s-cescocenc sw teneee-eom-arenentenes Palaeoscenidium flammatum Palacosceniidids) ---....-.+--<+:-+<=: IRGICOSPNGEN Gi enceesesndaseeses =e Partial Range Zone, defined DQIVGs: PYGESPONZOCOCNIA’ .2..c2224:s2sascscnsarsecon-censeeee==s=> PayMe SEMIS) geeceeeece ssctscs vee sseuvecess acecems ooacsseeseten scene vanccwacmecnsne™ type localities from ... 20, 21 24, 26, 27, 31, 32, 34, 35, 37, localityidescriptions) <-1-..-2-.-s-:s222s0seesseeve>ovese-onsee===== Pena Blanca Mountains ....................+- PRennsylvaniangees -ccaseuccscnssesscaresesann-are platyspina, Secuicollacta (?) plutonis; \GENOSPRGeV A. <2. ..2.2.000>sc0secodecorecwnsen2s5= arsenite neccons= Praespongocoelia (Spongocoelia) parva—Praespongocoelia (Spongo- coelia) kamitakarensis Assemblage ...........-.-.--+.++s0s0e+0++ 16 Praespongocoelia—Stylosphaera (?) magnaspina Partial Range TONEY oss nis vusde dnewese seas caede setae Praespongocoelia fusiforma PFACSPONGOGOEIIGDAIVG siren. nsuessepeareseousseetecaceesee-- == Praespongocoelia Taxon Range Zone ..........-...-00eeseeeeeeeeee ees 13 PrG@SPONGOCOCLIG waznes<ce<seeeeec-e=se== == Pre-Orogenicistratal :.se.c2.:c-2ceceecesseseoreoreccseeceeqeaesen ass - === IPridOliaWyerscessescecsrece acess cece ses prima, Stylactinosphaera Primary rod;idefined ....-:.-:.... Primary spinesunit, defined! <7. .2.2-<--2e-re--0+eo--22ncee eee seeeeeres =e 18 Pseudoaulophacilaes sescsteceotee sence oes soca en hee eoeeneee ener ne 27 Pseudorotasphaera (?) robustispind ........00-0000eee esses 3, 413227) Pseudorotasphaera (2) rotunda ...........0--00-+0s-00-sessce0ees 313527) Pseudorotasphaera hispida 3845 135 25.,26827 Pseudorotasphaera lanceolata ..........1.1.ceeeeceeeeeeee eee 385513, 26 IPSCUAOTOLASPNGENE! «:.2o.c 2c sssecene-sveeveeo senses 35458) 13; 14525527
PseudorotasphacriGae sscessseseercc or ereeree eee eee eee 18, 19, 25 Pseudospongoprunum (?) tauverSi .............4..06+ 7, 14, 16, 28, 38 Pseudospongoprunum sagittatum Assemblage Pseudospongoprunum Sagittatum ..........6..00eee0e eens a Pseudospongoprunum tazukawaensis Assemblage ..............-.- 16 PS@udOspOngOprumturn) 2. 2eonenc-n-caeeonseesnes aece eee eee eee 7, 28 quasirobusta; Stylospnaera 22 seey-sen-cones2e-sceee cere eee 39 ramuficans, Oriundoguttal ~.c...-ceessscns-ce---eo ese = see 31 robertsorum, Rotasphaera ................ we 22052122 e27, robustispina, Pseudorotasphaera (2) ...........000.c00ee00 3, 4, 13, 27 Rotasphaera beckwithensis. ..........+2012000000000- 2,8, 13s 14520521 Rotasphaerajdelicata™ 2. seen see s-- estes eee eee 2, 20, 21 Rotasphaera marathonensis ...............++- 2,8; 13; 192002127 IROLGSPHACrGINUAQ) wacecscoch pos. cree eeeeeeeseeeee eee ee 1, 20, 21 IROLASPRACNA QUAGI AIA Wee ectee sane ns cee eee eee 22122526 Rotasphaera robertSOrum .........0.c0.ceeeeeeneeeeeee es 2) 20ND 222, IROLGSPRGCKA Face neces oes one densecser ee 1, 2,'8;, 13; 145 16; 192205283 Rotasphaeracea—Devoniglansus unicus Partial Range Zone .... 13 Rotasphaeracea) <<. -2:<-cc0ss /accessuce: coeecnece scence eee 13, 18, 19 RotasphaeridimorphotypevAc oon s eee enc- conor ose se escort eeeeeee 2,22 Rotasphaerid morphotype BG .c-csecs-cecee see cence one eee eee 23 RotasphaeridSuperzone) x. ..c..-2--- ee eres ences eenes eee 9°13 rotasphaeridistructures scesscce ee eeee cease seeeee ner eres 8, 18, 19, 25 Rotasphaenidae, jes sco- cee cecec- eee eee sencceesenerees 185 19523525433 rotasphaerids” ssc.cs.c--seesse sees aeee ene 145 15; 16; 17, 185al9522525 rotunda, Pseudorotasphaera (2) ........-c.cceeesecneenseneeenes S13 -927, sagittatum, PSeUdOSPONZOPFUNUM ......cccccveeeeeeeeeeeee ees Santiago! Memiben 22. -2ecscr secs nce secs ences ences cceeeenceteeeer hemee teen Secondanyprod::defined! 2 t.csec.ce-seese- oes eae Secuicollacta (7) platyspina .........0.0+s0ese0e00e Secuicollacta ? exquisita Assemblage .... SecuicollactA QMOECNUAS <..2..2c-c2-c2cencnsessseseees sso eeeeesesee eee SCCuICOllACtAiCASSAS?. sacenucnasneceseneesesenestneee eee en eee i, 23} SCCUICOIIACIA CASS cavsteewsenteseness-eseecneee ence meaner 145195922223 ‘Secuicollactatfoliaspinellan cece. 2. sec ee no-one ee eee nee 1, 23, 24 Secuicollacta*sOlara: zs.c2cce-2 02-020 <2scensssee eoeeees 1, 8, 14, 23, 24, 25 SecuicollactaispwAs secs cen o-sesceseen es eesee reste nese neers ven mle25: ‘Secutcollacta'sp..ch: S. ROnrida) 22. co. een nessa ces eect nee nee neers 24 SCCUICOILACLAM <-penceeeeesceceseteacees 1,8; 15; 16; 18195 205210223 SimpsoniSprings: Mountain)... .2rc-ceeesecee- scence eeeree ey acemeesen 41 SOLAIGs SCCUICOIIACI A rscncaaceeateneseenee nce eee 1, 8, 14, 23, 24, 25 Southern!(Wrals) scccesssncsr epee: reseeeocine sce cceeee noes renee e eee eeeenaeeee 14 Tadiolaman’ taxa from. jcc.ccsese-eocectessacechestchoeee teeter 19, 23, 31 Splculitic Chert) gccsc--e-cec-staspaversseeces sors -neceeereaeeosnenpeeta eee eet 8 SDIMOSUS) ZAANAPDOLUS Grecaesesccsece eeheccreetsaseere ene 6, 9, 14, 16, 32 Spongocoelia parvus ( Praespongocoelia parva) .............6500005 38 Spongocoelia sp. nova A ISDONGOCOCIIC er serene wa ete cn tecsece a earen eee aeons eerie Spongodiscaceal #5.sces- ccc ates teceec sree cnnseasancnecceitns-eiee= eens SpOnguridaeist: essceetee ote ese eeeraecdes ees eee SPONQUTUS) oo onee teenies: acsee sss sere seereeee ee
Spumellarian indet. sp. A Spumellarian indet. sp. B Stylactinosphaera prima
ISEAPIACLINOSPRACN A eevee sores ene anor aac ennnaan se neceen teeter nee
Stylosphaera (2?) magnaspina Taxon Range Zone ...............- 13 Stylosphaera (?) MAQNASPINA .........2..2-00cceee eee eeee eee eees 5, 13, 39 Stylosphaera ? sp. A-Stylosphaera ? sp. B Assemblage .......... 16 Stylosphaerai?) Spi B) cc. esceus-see-coesoeeereee eee 16, 17, 39 Stylosphaera ?sp: © Assemblage’ 22-0. .csnsceneqensseaurene seem seen a= 17
Stylosphaeras? spyG, wescssccessseesseeer sec esdans ore inenecemencer ens 17, 39
SILURIAN RADIOLATION ZONATION, WEST TEXAS: NOBLE 55
SEV OSPNGCrAYMISPIAG, Vee acessdedssen erences suensesatecawectencevestiseenessnses 39 Stylosphaera quasirobusta ... IS): OSPHACKAS he seas suc sdecsescetseve Benouehabeseeccuercueeseeneets Sulphur Springs,
Jocalityedescri ptlonig. s.seterne se. sere eecnececcscescce sees arenpece-senccese 40 SVE OLOPEMIC Strata ys sursscsre ste ereceas far sset-aurecsaccsteseteneceoes 6, 7,8
RELL CLIP TLIC PIVIGIUNELIy mea snassetestavccenecwecesvceseeeeesceeeceseeeecevece tauversi, Pseudospongoprunum (?) ... Taxon range zone, defined ............. Pen tings defined terse vessce score ce sce edc seerours meet ennneuens cameidoseuls aac FETUS PZ AAI ADDOLUSE saxcste San en cone renee eee re eee
LEMUIS WZ AALODDOLUSISPr alls) caeatesee se caece ace ene sane erence cen eetee MesnusHsOrmatl ON\erseetee esse see ca recto ss ee eee ees neste see eee Tetrentactinia barysphaera—Ceratoikiscum famenium Zone ... 23 RI ODITES Wesete ne coeeie sos dons coe: de spcccerse saceaiuecsi se eclcevcsecsncessceeese 16
uadrata, Rotasphaera .... udosa, Bipylospongia unicus, Devoniglansus
VANISPING A OMIUNAOOULLAI(2) i seneseeces -oeneree ce setee ese tee eee 6,9, 14, 31 Wralliserodusisp sindetamnecstter cece eee cee oes ston note eee 14 Wienlockiani yy t.ssecsac sie een rece ee aese ae me otearensaetees 14, 16 Wood Hollow,
type localitiesiat: 2: sccsccss ss stene sees -c roote nection ons ace tommone eeeese esos 26
localityidescriptiony ssccsocsccescore ee voces oo sos nsec eeeteae mee sees 41 VOSRIKICNSISWZAAlADDOLUSH ie eetecee enna eae 6, 16, 32 Zadrappolus lunaris 33 Zadrappolus sp. A 333. AAT ADDOIUS SP aa (tal CI 15) eee nee een ee 6, 32 LAG ADD ONISESDINOSUSa we tercestn cesta Nestea te eee sear 6, 9, 14, 16, 32 ZQGV AD DOWUSHICTILLLS areeeeeree oe eee ee 6, 13, 32 Zadrappolus yoshikiensis Assemblage ..............0...0.00.00e-00-+ 16 ZAAVANDOIMUSEVOSRIKICNSISH eeeers sete seteceeeeee eee eeeee ree 6, 16, 32 LAGVADDOIUIS Marccraseaae ne tenet eee 65/95 135 14515, 165.17, 32
PREPARATION OF MANUSCRIPTS
Bulletins of American Paleontology usually comprises two or more sep- arate papers in two volumes each year. The series is a publication outlet for significant, longer paleontological monographs (/.e., more than approximately 50 printed pages), for which high quality photographic illustrations and the large quarto format are required.
Submissions are welcome from any author, regardless of institutional or organizational affiliation. Authors must, however, be members of the Paleonto- logical Research Institution at time of publication; annual membership is currently US$20.00. Publication costs of the Bulletins are heavily subsidized by the Insti- tution, but authors are currently required to pay illustration charges at a rate of $120.00 per plate and $35.00 per text-figure.
Manuscripts must be typewritten, and double-spaced throughout (including direct quotations, tables and references). All manuscripts should contain a table of contents, lists of text-figures and/or tables, and a short, informative abstract that includes names of all new taxa. Format should follow that of recent numbers in the series. All measurements must be given in the metric system, alone or in addition to their English system equivalents. The maximum dimensions for pho- tographic plates are 178 mm x 229 mm (7 inches x 9 inches; outlined on this page). Single-page text-figures should be drafted for reproduction as single column (82 mm; 3'4 inches) or full page (178 mm; 7 inches) width, but arrangements can be made to publish text-figures that must be larger.
Authors must provide three (3) printed copies of the text and accompanying illustrative material. Authors are strong/y encouraged to prepare their manuscripts on word processors, as this considerably expedites publication. On initial sub- mission, however, only printed copies of the manuscript should be sent; the disk copy should be retained so that revisions can be made after the review process. The text and line-drawings may be reproduced xerographically, but glossy prints at publication size must be supplied for all half-tone illustrations and photographic plates. These prints should be identified clearly on the back.
Referenced publication titles must be spelled out in their entirety. Refer to a recent number of the Bu//etins for details of reference format. Citations of illus- trations within the text bear initial capitals (e.g., Plate, Text-figure), but citations of illustrations in other works appear in lower-case letters (e.g., plate, text-figure).
Format of systematic descriptions should follow that in any recent number of the Bulletins.
Original plate photomounts should have oversize cardboard backing and strong tracing paper overlays. These photomounts should be retained by the author until the manuscript has been formally accepted for publication. The approximate position of each text-figure in the text should be indicated. Explanations of plates and text-figures should follow the References Cited.
pemco INC >
8 2931
IWAVEL ATA
3 2044 072 271 96
8
a ssh ee los asbhtty interst fanaa
Pac
Pe pace
seats f; Bal
iy SiptAtee cic ay ere te ntconenere the eee ey iting Tah o
ats
ain y aoe ey iy
epee pi
ttl see
ca ier ote evens
Soretrety Tes
eral atte ee a
KA
eat Sey
an Enis ue