Mains MM tore sn DiAse a Aas 2A Se) Lees Soares Bch hh tues Ne ot ti Coy pee De Ve 5 AAS AA haze Vatios. ra View iss, Pons So HMR GL Ry S ate “ DENSON Te peaeics et Oct ores REC an cue pee ee StU eu wet Fie wrens, B Va wich Soop. eee rs ro A ergs ays evi e nd fans orate see od WS eg pe RON pre ona farrecry ee YY ee ee: i Sete. Pt gp pole x HARVARD UNIVERSITY e Library of the Museum of Comparative Zoology VOLUME 80, NUMBER 313 SEPTEMBER 8, 1981 Paleontology, Taphonomy and Paleoecology of the Palmarito Formation (Permian of Venezuela) by Peter R. Hoover Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York, 14850 U.S.A. Library of Congress Card Number; 81-83795 Printed in the United States of America Allen Press, Inc. Lawrence, KS 66044 U.S.A. CONTENTS BAUS ETA Ctra ss oetay be veze sarees sual says, si'ie's 6/3 ar nten gp epiva'a al sishccehavetr'e lereteveys NOMEN gooocsssonconase coondaDOOOODONNOOdOGODOOUODEDNN ES OV ARTETIGIS: 4g foo os sabe ona nee pepcodmare sos onas Du LTMOCMEHOM epascesoobocdoe boopapepanD ese pdeboucontuDEor The Palmarito Formation IRECIONAIESC LUMO amc trrerracre etter Pelevereierletalete aie svave cersioreieverskeiere EW SCONIGA BS CUEN Garay ccckeresearieretetereeiecisherersueieseueccusinne Co eerateiete Biostratigraphic) Correlation’ 9-2. <<<. <2-- 0+ 3-0 a= Lithic and Faunal Analysis ITTOCMCTON “eecodgococaapneeusncoboodoDonnanEononoec[ ithic Description) Mechniques) see cci-lllse nee ae clio BAUM AL MIE SUS sae epec crags 7a ene csc arc ereie eferelaiare/eyaveterstat ays ie, or cyexayeve MAP NOMOM VaMeerct iret conererorererelololorelelciesotstate evscerers.cniererate PARTIEOWSY woodcdeeacooedsdnaanoopnnaonedsaadeaeet Collecting Localities MEOGALI ty) Tay svesesare-sysicytistai sveresiedisiais spew ee) sisieidierevs simvesaee is IL@VCANNT 2” Sipe cs Coe URS OO OOOO Taine ner areas | Lrovers [ais he Staemte SoS One mid ee Ce a icc eae oer reo MBO Pali ty 4 totes cta:c/ocsyniars suey anche Sree sais we sree sseyero areas MEO CALL 750 Nevetos re. 3: x7x tsi ceo ecetesarehshavessysqsiesov co ei vv otevs Sats zisrare I LOVATO, On oa eneas soopopode oy an oemaUoomoneos soemnaa ae MB OC ALLEY Aimer raee trea aer hc raens oontish Sakeieserene cect ee lots are MBOC ALLY A Ome ester ysr saeco fete acues susp sistaysteiah sy aversnwe crepe eiayare wicteeNO MBO CALEY) ILO) ares: axe where rescinvwtes sis cavsvoisrs: sxassievele oeiarsaievars eevee eis ME QC ALA ya ete ces areca tages ayes es aise Ysieieseses wos E aie ee wid eases MBO Alby AUS ie cece states cassatescinve. ov oreinpetek ari eucledanmncavs: axes Skat aevereene Depositional/Environments) 2c} -aceieme cise ele ceree ee Organism/Substrate Relationships ....................----+ REEMA DUR ALLO bar nescecysTsictcke nesters etter elernys ie eres taeia ernie ayes ss Samplin ge ficiencysINdexa mace secession eiiey= Introduction to Systematic Paleontology Ehilosophicali€onsiderations’ @2.0--52- sss 062022626 one Format TMETMINOLO SY ers v/s tate ole stersrs stains olocie se oma s «Mieke Siolonie sie s¢ 38 hy peyREPOsitomles! crimes ercieiemnrecieinerriericre 39 Measurementsieeccrresser octane en eet orci ae oe 39 Brachiopod Systematic Paleontology Hamily;CraniidaesMenke pane eee ee eee eee ere 39 Family Schizophoriidae Schuchert and LeVene ........... 40 EamilyDerbyiidae'Stehlin=-m--sceeenece etre eee cee 41 RamilyiMeekellidae)Stehlig --ssacaeeriicecein cece iiie ie taere 47 Family Rugosochonetidae Muir-Wood ..................-. 49 Family Aulostegidae Muir-Wood and Cooper ............. 55 Family Cooperinidae Pajaud .....................2.0005 57 Family Rhamnariidae Muir-Wood and Cooper ............ 59 Family sMarginiferidae:Stebli) ease cee eerie eer 62 Family Paucispiniferidae Muir-Wood and Cooper ......... 66 Family Linoproductidae Stehli ....................0.220. 70 Family Retariidae Muir-Wood and Cooper ............... 72 Family Echinoconchidae Stehli .........................-- 74 HamilyaDictyoclostidae:Steblin wasencne saci cetera 74 Family Lyttoniidae)Waagen) <.--.-4.-.-. sees = ose ene 82 Family Pontisiidae Cooper and Grant .................... 84 Family uncertain (Rhynchonellacea) ..................... 87 Family sRetziidaeiwaagent a eeree-ta cece ae ceenen 88 Kamily; AthyrididaesMc@oyin.-e 4. aceecce ace ceases 93 Family Ambocoeliidae George ......................005 96 RamilysBlythidaeybredeniksmaseeiceecceeee cee 98 RamilysSpinifendacs kone eee reer eeer nr ticereereteeeere 100 Family Reticulariinidae Cooper and Grant ............... 102 Family Dielasmatidae Schuchert ........................ 104 Family Pseudodielasmatidae Cooper and Grant ........... 105 Family Cryptonellidae Thomson .....................--- 106 ReferencesiCitediiracmemierewicterhierscirerataciciete citer teeter 109 PIAteS 3 oc eisetateere eit yet eee ees See 117 Tn OX: Fares acsrcucrererey corel feteens ouerarcicee tones oy evseavnretcl sere eve eneeetat reno 128 LIST OF ILLUSTRATIONS Text-figure ils Maps showing location of eleven Palmarito Formation fossil assemblages . Similarity coefficient matrix for brachiopod genera in Palmarito Formation fossil assemblages Dendrogram showing similarities in brachiopod gener- ic composition among Palmarito Formation fossil assemblages mermrire iit t either tiie: Brachiopod occurrences and taphonomic indices in eleven collecting localities within the Palmarito Forma- tion Habitat-type distributions for species and individuals in Palmarito Formation brachiopod assemblages ... Permian Ratio for brachiopods, calculated for well- known localities of marine Permian fossils, plotted Against latitud clare rene rere artiste yeni aie Permian Ratio and Sampling Efficiency Index for nine Palmarito Formation and 35 Road Canyon For- mation articulate brachiopod assemblages . Sampling Efficiency Index for Permian articulate brachiopod assemblages, calculated for well-known collecting localities, plotted against latitude ........ Shape variation of dorsal valves of four samples of Cooperina from the Permian of West Texas and Venezuela . Comparison of shell form of two population samples of Echinauris bella Cooper and Grant (1975) . Scattergrams of dimensions of two population sam- ples of Hustedia hyporhachis n. sp. from Venezuela and one population sample of Hustedia consuta Cooper and Grant (1976b) from West Texas Page 14 15 Bee PN Mea va Ter oper ove seusishet ibe desiete ole foldout inside back cover Ww tr 34 36 64 Table tr n LIST OF TABLES . Occurrences of brachiopod genera in Palmarito For- mation fossil assemblages . Comparison of brachiopod generic composition of the Palmarito Formation and of selected Permian biostratigraphic units in the West Texas region . Comparison of brachiopod generic composition of Palmarito Formation fossil assemblages and (or) as- semblage groups, with West Texas stratigraphic . Genera and families of Arnold collection Palmarito Formation brachiopods identified by H. M. Muir- Wood and P. R. Hoover . Results of rock constituent analyses of Venezuelan marine Permian rocks containing appreciable num- bers of silicified fossils . Habitat-type classification of Palmarito Formation brachiopod genera Familial affinities of Palmarito Formation brachio- POU BENET Aa Aaj cree. ces sorts ev euesseesoiet ete elle eee Permian Ratio and Sampling Efficiency Index of Pal- marito Formation articulate brachiopod assem- EV Coh SEomnnCa Doma e Oe mOnnSacno Amano SDS a0o0 Measurements of dorsal valves of Cooperina inex- pectata Termier, Termier and Pajaud (1966) from locality 6, Palmarito Formation ................... Statistics calculated from measurements of dorsal valves of two species of Cooperina Termier, Termier and Pajaud (1966) Page 14 32 33 60-61 Bue (F/G MUS. COMP. ZOOL, LIBRARY ‘TOLUME 80, NUMBER 313 SEPTEMBER 8, 1981 Paleontology, Taphonomy and Paleoecology of the Palmarito Formation (Permian of Venezuela) by Peter R. Hoover PALEONTOLOGICAL RESEARCH INSTITUTION Officers IPRESTDBNIT. | Vie cls cteatenca acne eit ooo old Se ent onan ote aes orate JOHN POJETA, JR. VICE-PRESIDENT Ds potest ce ee el ce ss ok arson a ayn cch oe rolls oe ee eerie Bruce M. BELL SECRETARY Ath EOS NAUGAY Sisal ea aeic pes hime any AOR aerate PHILIP C. WAKELEY TREASURERO Na) fe ere ee crete chee auieT ae elsTe Se oem te nero Micketae E. JOSEPH FARRELL ASSISTANT UNREASURER octets: cm foe opie cio p eyasinciansccns sie a trap aieele JOHN L. CISNE DIRECTORY 310 can ora eer eae ars hans sisi vik er Me ue eer ae eke) oan Oe eee ee PETER R. HOOVER DIRECTORVUEMERITUS. ots. cuties oxac sieekee ie taecine ene KATHERINE V. W. PALMER LEGAL COUNSELS) sicick circa he wre ieee oe ee ale eee ARMAND L. ADAMS Trustees Bruce M. BELL (to 6/30/84) PORTER KIER (to 6/30/84) RICHARD E. Byrb (to 6/30/83) DUANE O. LERoy (to 6/30/84) KENNETH E. CASTER (to 6/30/82) WILLIAM A. OLIVER, JR. (to 6/30/83) JOHN L. CISNE (to 6/30/82) KATHERINE V. W. 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Hoover Director Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York 14850 U.S.A. 607-273-6623 PALEONTOLOGY, TAPHONOMY AND PALEOECOLOGY OF THE PALMARITO FORMATION (PERMIAN OF VENEZUELA) By PETER R. HOOVER Paleontological Research Institution 1259 Trumansburg Road Ithaca, New York 14850 USA ABSTRACT The Palmarito Formation of the Venezuelan Mérida Andes is late Early and early Late Permian (Roadian—Wordian) in age, and contains a well-preserved, diverse fauna including many forms of a distinctly Tethyan aspect. Its carbonate sediments were deposited in a variety of marine, warm-water shelf environments, under variable energy conditions. Values of both diversity (as Stehli’s Permian Ratio) and sampling efficiency (as his Sampling Efficiency Index) for Permian brachiopods are enhanced by bulk collections of rock containing silicified fossils. On a global scale, the observed southward decline in sampling efficiency is chiefly a result of less intensive study of faunas in southern regions. No parameter relating substrate character to faunal composition was found. The brachiopod fossil fauna includes 32 genera of which three (Stauromata, Costicrura, and Anapty- chius) are new, 44 species of which 12 (Derbyia auriplexa, Derbyia deltauriculata, Dyoros acanthopelix, Stauromata esoterica, Xenosteges minusculus, Rugatia intermedia, Spinifrons grandicosta, Collemataria venezuelensis, Hustedia hyporhachis, Cos- ticrura minuta, Aneuthelasma globosum and Anaptychius minutus) are new, and two subspecies of previously described species, one of which (Peniculauris subcostata latinamericana) is new. Internal structures of a new chonetacean brachiopod genus are developed by application of new serial peel reconstruction techniques. RESUMEN La Formacion Palmarito de los Andes Meridenos de Venezuela es de edad Permico Inferior alto a Superior bajo (Road- ian—Wordian), y contiene una fauna diversa y bien preservada, incluyendo muchas formas de un aspecto distintivamente Teth- iano. Sus sedimentos calcareos fueron depositados en una variedad de ambientes marinos, de aguas calidas y someras, debajo de varios condiciones energéticas. Los valores de diversidad (expresada como la *‘Permian Ratio’’ de Stehli) y de la eficiencia de muestreo (expresada como su ‘Sampling Efficiency Index’’) fueron mejorados para los braquidpodos Pérmicos por colec- ciones masivas de rocas que contienen fosiles silicificados. En una escala global, la declinacion que se observa hacia el sur en la eficiéncia de muestreo se debe principalmente al estudia menos intensivo de faunas en las regiones septentrionales. No se ha podido hallar ningun parametro que relacione el caracter fino del sustrato a la composicion faunistica. La fauna fosil de bra- quiopodos incluye 32 géneros, de los cuales tres (Stauromata, Costicrura y Anaptychius) son nuevas, 44 especies de las cuales 12 (Derbyia auriplexa, Derbyia deltauriculata, Dyoros acanthopelix, Stauromata esoterica, Xenosteges minusculus, Rugatia intermedia, Spinifrons grandicosta, Collemataria venezuelensis, Hustedia hyporhachis, Costicrura minuta, Aneuthelasma glo- bosum y Anaptychius minutus) son nuevas, y dos subespecies de especies previamente descriptas, de las cuales una ( Peniculauris subcostata latinamericana) es nueva. La estructura interna de un nuevo geénero de braquidpodos (Chonetacea) es descubierta por la aplicacion de una nueva técnica por laminas seriadas. ACKNOWLEDGMENTS Financial and logistic aid from the following sources, without which this dissertation could not have been completed, is gratefully acknowledged: Ministerio de Energia (Direccion de Geologia), Re- public of Venezuela; Geological Society of America Penrose Bequest Research Grants 1566-72, 1685-73, and 1804-74; Sigma Xi Grants in Aid of Research in 1973 and 1974; National Science Foundation Research Grants GA16827 and GA26210 (awarded to F. G. Steh- li); Smithsonian Institution Research Foundation Pre- doctoral Fellowship (1974-1975). For expediting and aiding my field work from their positions in the Ministerio de Energia, in Caracas and in Mérida, I am indebted to the following persons: Dra. Cecilia Martin, Dr. Alirio Bellizzia, Dr. R. Gar- cia-Jarpa, and Dr. Peter Motiscka. I would like to ac- knowledge the friendship and unfailing help which I received from many of the people of Venezuela, es- pecially Don Luis Maria Molina y Vega, of Canagua, Estado Mérida. I would also like to thank those who helped me in the field: Rito Altube, Clodomiro Garcia, Alfonso Mendes, Domingo Molina, Leovijildo Molina, Vicente Molina, Antonio Mora, Pastor Mora, Silberio Mora, Antonio Rondon, Abundio Rivas and Jesus Uzcategul. I also wish to thank Rex Doescher (Dept. of Paleo- biology, USNMNH, Smithsonian Institution, Wash- ington, DC, U.S. A.) for his help in locating necessary references. 6 BULLETIN 313 Thanks are due to the hard-working paleontologists who took their time to identify non-brachiopod ma- terial from the Palmarito Formation: Olgerts L. Kark- lins (OLK), of the U.S. Geological Survey, Washing- ton, D.C., identified bryozoans, W. M. Furnish (WMEF), B. F. Glenister (BFG), and C. S. Lee (CSL), of the University of Iowa, Iowa City, Iowa, identified cephalopods; the late A. G. Smith (AGS), of the Cal- ifornia Academy of Sciences, San Francisco, Califor- nia identified chitons; C. T. Scrutton (CTS), of New- castle-upon-Tyne, England identified corals; the late J. J. Burke (JJB), of the Cleveland Museum of Natural History, Cleveland, Ohio, identified crinoids; Porter M. Kier (PMK), of the National Museum of Natural History, Washington, D.C. identified echinoids; Ray- mond C. Douglass (RCD), of the U.S. Geological Sur- vey, Washington, D.C., identified foraminifera; Ellis L. Yochelson (ELY), of the U.S. Geological Survey, Washington, D.C. identified gastropods; I. G. Sohn (IGS), of the U.S. Geological Survey, Washington, D.C., identified ostracods; N. D. Newell (NDN), of the American Museum of Natural History, New York, New York identified pelecypods; J. K. Rigby (JKR), of Brigham Young University, Provo, Utah identified sponges; C. K. Chamberlain (CKC), now of the Cities Service Co., Denver, Colorado, identified trilobites. Drs. Peter Jung and Rene Panchaud of the Naturhis- torisches Museum of Basel, Switzerland kindly pro- vided me with casts of important type materials. Dr. J. Howard, of the Skidaway Institute of Oceanogra- phy, Savannah, Georgia, kindly provided X-radio- graphs of rock samples. I am indebted to P. O. Banks, L. Burkley, S. Franks, J. Helwig, G. Klar, P. McCall, and J. Murphy of Case Western Reserve University, Cleveland, Ohio, and R. G. Shagam of the University of the Ne- gev, Beer-Sheva, Israel, for stimulating discussions on many aspects of Central and South American geolog- ical problems. The ‘*‘Take a Brachiopod to Lunch”’ bunch of the National Museum of Natural History (Department of Paleobiology) and the United States Geological Sur- vey (Paleontology and Stratigraphy Branch), including G. A. Cooper, J. T. Dutro, Jr., M. Gordon, R. E. Grant, R. B. Neuman, and B. R. Wardlaw are here collectively thanked for many intellectually stimulat- ing and (or) provoking discussions. Drs. F. G. Stehli and R. E. Grant acted as co-ad- visors through the course of this study, and helped knead the manuscript drafts into professionally read- able thesis form. Drs. R. E. Grant and J. W. Wells reviewed the revised manuscript. I would like to ex- tend my profound thanks to these individuals for their aid and comments. This work is dedicated to my wife Caroline, for re- maining sympathetic to me and my chosen profession. INTRODUCTION For several years paleontologists and biologists have been interested in the global diversity patterns of marine organisms, particularly those that can be used in interpretation of the fossil record (Stehli, 1957; Fischer, 1960; Stehli et al., 1969; Waterhouse and Bonham-Carter, 1975). Stehli (1971) has related lati- tudinal taxonomic diversity gradients to the distribu- tion of families of thermally-tolerant cosmopolitan, and thermally-sensitive endemic Permian articulate brachiopods. He found measured diversity to be high- ly variable, and devised a statistic, the Permian Ratio, that minimized diversity variations caused by inade- quate sampling. This ratio is defined as: = C Cc where > = the total number of brachiopod families identified, and C = the number of globally cosmopol- itan families identified at that locality. By making the number of cosmopolitan forms less significant, the sta- tistic increases the significance of the endemic (and thermally-sensitive) forms recovered. Permian Ratio values (see Text-fig. 6), plotted against latitude, in- crease from the poles toward a maximum near, but north of the present Equator. Some low-latitude sta- tions have anomalously low Permian Ratio values. Stehli also observed that sampling efficiency, as mea- sured by the percentage of possible global cosmopol- itan families recovered at any locality, declined toward the south from about 30° North latitude. A potentially fruitful line of investigation was to try to determine, through the study of new collections, if anomalously low Permian Ratio values at a selected equatorial sta- tion were due to sampling inadequacy, and, if so, in what ways sampling could be improved. I also hoped to explain why otherwise cosmopolitan families were missing. Central and South America are comparative un- knowns, in terms of Permian brachiopods. South of Mexico, well-documented Permian brachiopod faunas of Tethyan aspect are known only from Guatemala and from the Titicaca region of Peru and Bolivia. For- mal description and illustration are necessary prere- quisities for use of a fauna in diversity studies, as they enable an investigator to verify taxonomic assign- ments for himself. Between Guatemala, at 16° North latitude, and Peru, at 7° South latitude, numerous fau- nas had been reported in faunal lists, but none had been comprehensively treated. When the opportunity for study there arose, I undertook a rigorous system- PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 7 Mérida State UL Qda El Palmar ee approx. | km watercourse mule trail V5 1°21'w © Mucuchachi settlement O collecting @ locality to to Mucuchachi weveeeeeP Mucuchachi Text-figure 1—Maps showing location of the eleven Palmarito Formation fossil assemblages collected for this study. atic, taphonomic and paleoecologic survey of the fos- sils, especially the brachiopods, of the Permian Pal- marito Formation of the southwestern Venezuelan Andes, at approximately 8° North latitude. During the rainy season—June and July—of 1971 a reconnaissance expedition to the type area of the Pal- marito Formation was undertaken. This area is located about 250 kilometers south of the city of Mérida, Ven- ezuela (Text-fig. 1), and at that time was reached by jeep, mule and foot from that city. Samples from as 8 BULLETIN 313 many fossiliferous exposures as possible were taken: the main purpose was to find those exposures that promised optimal sampling, by means of collection of silicified fossils. Forty-one localities sampled during that field season yielded about 500 kilograms of rock and fossils that was returned to the United States for study. During the remainder of that year and the two following, specimens were prepared, and the most promising localities earmarked for re-collection. The next field season—March through April, 1973—came at the end of a protracted dry season in Venezuela, making access to localities easier than it had been pre- viously, and many of the logistic hardships encoun- tered in 1971 were eased. Nine of the original 41 lo- calities were re-sampled in bulk: several additional samples that looked promising were taken as well. Approximately 1300 kilograms of fossil-bearing matrix from the Mérida Andes was returned from the 1973 season. No mapping was undertaken, because field time was limited, and because preliminary mapping had already been done by agencies of the Venezuelan government. The results of the study are several. The brachiopod specimens used in preparation of Arnold’s 1966 faunal list for the Palmarito Formation were re-examined. It was determined that the brachiopod diversity had been overestimated and that many identifications not only were incorrect but also biostratigraphically mislead- ing. Examination of Arnold’s collections, in combi- nation with those made by the author, showed the unit to be largely of latest Early Permian (sensu Grant and Cooper, 1973) rather than Permocarboniferous age, in the type area. Examination of all available fossil assemblages re- covered from the author’s collections showed that the Palmarito fauna is truly Tethyan in aspect and that its previously reported temperate character was probably largely a result of the comparative rarity of the hard substrates necessary for the attachment of many en- demic Tethyan brachiopod forms. The decline in Sam- pling Efficiency Index southward from about 30° North was determined to be in great part a result of less intensive study of those faunas, but no definitive test of causal relationships could be made. Attempts to find a quantitatively measurable parameter that could relate substrate character and faunal composi- tion were unsuccessful, but one character tested—silt/ clay ratio of insoluble residues—may be an indicator of energy regime (Hoover, 1976b). The Palmarito as- semblages sampled are inferred to have been depos- ited in a variety of warm-water shelf environments, from beach or bar to level bottom below wave base. The entire fauna is reported in the form of faunal lists, while the brachiopod fauna is identified, de- scribed and figured, and is discussed in terms of its biostratigraphic, paleoecologic, taphonomic and pa- leogeographic significance. The brachiopod fauna in- cludes 32 genera of which three are new, 44 species of which 12 are new and 2 subspecies of previously existing species, one of which is new. THE PALMARITO FORMATION REGIONAL SETTING It is generally agreed that late Paleozoic marine sed- iments in the Western Hemisphere were deposited in a geosynclinal basin or series of basins. The form of this trough, however, is unclear, although several hy- potheses have been proposed. These may be separated into two groups, whose basic difference lies in the disposition of the present Caribbean Islands. In Perm- ian continental reconstructions, these troublesome fragments, for which no Late Paleozoic paleomagnetic data are available, most commonly have been placed within a reduced Caribbean Sea. For example, the hy- potheses of Carey (1958) and Freeland and Dietz (1971) place most of Mexico in the position of the pres- ent Gulf of Mexico in pre-drift time, and rotate the pre-Mesozoic Yucatan and Central American base- ment blocks to produce a Late Paleozoic continental mass in the Gulf Region. In the last decade, another family of hypotheses has arisen that seem to require less strain on both imagination and the laws of physics. Hamilton (1966), Walper and Rowett (1972) and van der Voo et al. (1976), assume an opposite sense of rotation of the region which appears as an overlap in the ‘Bullard Fit’’ (Bullard et al., 1965), and place the resultant southern tip of Mexico off the west coast of South America. This produces a more intimate pre- Mesozoic connection of the southern Appalachian, Ouachita, Mexican-Central American and northern Andean geosynclinal belts, which in turn helps to ex- plain the great faunal similarity of the Palmarito and its stratigraphic equivalents in North America. Paleo- magnetic studies necessary to test the sense of rotation of the critical Central American and Caribbean frag- ments have not been made, as rocks of suitable age and type have not been examined from many parts of that region (Hicken er al., 1972). Itis hoped that future paleomagnetic studies, in combination with pertinent Upper Paleozoic faunal studies such as this one, will provide data that can be used in such a test. Permocarboniferous sediments were deposited over a great area of Central and South America, but this time was not one of extensive oceanic development, PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 9 relative to the Early Paleozoic. In addition, known and studied exposures of marine Upper Paleozoic rocks in the area are rather limited. Many parts of the region have been affected by severe diastrophism since Permian time, so that much Upper Paleozoic sedi- mentary section has been removed by uplift and con- sequent erosion, or faulting. Great thicknesses of fos- siliferous strata have been metamorphosed to the degree that fossils can no longer be recognized and identified. Without such aids, the depositional age of the units cannot be determined directly. Many known fossil localities in the region are not fully exploited, in part due to poor accessibility, thick vegetative cover, high degree of slope and rapid weathering. Until recently, little detailed geological investigation had been carried out in many of these areas, except in connection with petroleum company operations. Recent literature syntheses and the work of national geological surveys or ministries of mines, in combination with the International Stratigraphic Lexicon project, have aided in the resolution of many of these problems. Though on present latitudinal coordinates, Texas lies north of the Equator and far from exposures of the Palmarito, it is a proper place to begin a more detailed regional discussion. The Permian strata of West Texas and adjacent New Mexico have been stud- ied assiduously since Shumard (1858, 1859) made his original reports. Most portions of the diverse fauna have been reported in monographic form. The bra- chiopods alone have been treated in four monographic studies (Girty, 1909; R. E. King, 1931; Stehli, 1954; Cooper and Grant, 1972, 1974, 1975, 1976a, 1976b, 1977). Because of this concentrated and detailed study, and the vast amount of comparative material available (over 72 tons of matrix collected and pro- cessed since 1939 at the USNM alone), the West Tex- as sections have become a Western Hemisphere stan- dard for both faunal comparison and stratigraphic correlation in the Lower, and lower Upper Permian. Stratigraphic terminology used in later discussions fol- lows that of Cooper and Grant (1972). Palmarito-equivalent strata are known from many areas in Mexico (Lopez-Ramos, 1969), along the course of the Paleozoic geosyncline that follows the axis of that country. Lopez-Ramos reported 28 studied marine Permian localities in Mexico, extending from Sonora in the north to Chiapas in the south. The sed- imentary histories of the exposures differ, tending to support the separation of these areas during the Late Paleozoic. Two sections in Mexico have received rigorous fau- nal treatment. Cloud (in R. E. King et al., 1944) stud- ied the exposures at Las Delicias, Coahuila, where the section consists of limestones, mudstones, sandstones and conglomerates, and spans the Permian from Wolf- campian to apparent Ochoan-equivalents. Over 3000 m of section are exposed. Cooper et al. (1953) ex- amined the marine Permian exposures at E] Antimonio in western Sonora. Strata of Word age exposed there are about 500 m thick. The basinal complex in Mexico continues through Guatemala and British Honduras and may extend into the Caribbean along the trend of the Cayman Ridge and Bartlett Trough (Dengo and Bohnenberger, 1969). Although these southernmost Permian marine expo- sures in Central America have been known since the pioneer studies of Sapper (1937), relatively few have been investigated paleontologically. Stehli and Grant (1970) reported a diverse brachiopod fauna from the Chochal Limestone, of the Department of Huehuete- nango, Guatemala, that shows close similarities to the Palmarito fauna. This unit, now placed within the re- gionally more applicable Santa Rosa Group (Clemons et al., 1974) has been correlated with the Leonard Formation of the West Texas area, on the basis of brachiopods (Stehli and Grant, 1970), fusulinids (Hen- best, in Roberts and Irving, 1957; Kling, 1960) and ammonoids (Glenister, pers. comm., 1974). Hoffstet- ter (1960) reported a Permian fauna from the Macal Series of the Santa Rosa Group of Belize, but pre- sented only a faunal list. No Upper Paleozoic marine rocks have been reported from the Caribbean virga- tion. Following the apparent structural trend into the South American continent, the first rocks of this char- acter encountered are those of the Palmarito Forma- tion. The Palmarito, like many Permian Tethyan units in the Western Hemisphere, consists of a predomi- nantly clastic, terrigenously-influenced lower shaly member and a predominantly marine upper limestone member, which ranges in age from Late Leonardian to Early Guadalupian. Rocks of similar lithic character from the Sierra de Perija in Colombia (Trumpy, 1943), contain a fauna of sponges, foraminifera, crinoid re- mains, brachiopods, gastropods and cephalopods (Burgl, 1973). To the writer’s knowledge only the fo- raminifera (Miller and Williams, 1945) and cephalo- pods (Thompson and Miller, 1949) of this area have been systematically treated in the literature. Expo- sures of questionable Permian age have been reported from other areas within Colombia (Burgl, 1973; Stehli, pers. comm., 1974), but none has yielded significant faunal data. Upper Paleozoic marine rocks of the Macuma For- mation are known in one outcrop and one well in the Cutucu Mountains south of Quito, Ecuador. A fauna 10 BULLETIN 313 of Pennsylvanian age including brachiopods, bryozo- ans, and crinoid remains was recovered from the lower part of the unit (Dozy, in Tschopp, 1956) and two Pennsylvanian foraminifera were recovered from the lower part of the thicker upper member (Baggelaar in Tschopp, 1953). The uppermost 150-200 m of the unit has yielded a brachiopod-bryozoan fauna to which Goldschmid (in Tschopp, 1953) assigned a latest Penn- sylvanian to Early Permian age. Stehli (pers. comm., 1974) has mentioned the existence of Permian red beds in Ecuador, but no other marine strata are known. The Upper Paleozoic section is relatively complete in Peru. Mississippian, Pennsylvanian and Permian strata have been identified (Newell, Chronic ef al., 1953) but only the Pennsylvanian and Permian are de- monstrably marine. Mississippian strata previously re- ported (Murphy in Megard ef al., 1971) as marine, have, on reconsideration (Murphy, pers. comm., 1974) been assigned to the Pennsylvanian. The Penn- sylvanian marine strata are equivalent in age to the Itaituba Formation of Brazil. The Copacabana Group in Peru as well as in much of Bolivia and adjacent Argentina and Chile, has pre- viously been considered equivalent in age to some lower portions of the Palmarito (Newell, Chronic et al., 1953; Arnold, 1966). Outside the above areas, the record of holomarine Permian in South America is poor. Between 50° and 52° South latitude, in the Madre de Dios Archipelago of Chile, fusulinids that indicate an age ranging up into the Permian have been recovered from a thick (ca. 5000 m) series of limestones (Cecioni, 1956; Douglass and Nestell, 1976). Cecioni reported the presence of a rich and well-preserved fauna in addition to the fo- raminifera, but included no descriptions or illustra- tions. Meyerhoff (1970) considered this unit to docu- ment deposition in warm water and thus to be an extension of the Permian Tethyan belt. Such a con- clusion appears unwarranted on the basis of fusulinid evidence alone, as fusulinids themselves are not in- dicators of warm-water conditions (Ross, 1967; Dun- bar, 1973). There were, in addition to the marine deposits in what might be termed the Upper Paleozoic Andean geosyncline, other contemporary marine deposits, within and between the relatively stable cratonic areas of South America. Local submergences and incursions at cratonic borders periodically allowed minor sedi- mentary deposits to accumulate. Itaituba-equivalent (mid-Pennsylvanian) strata are apparently widespread in parts of Brazil, Argentina, Paraguay and Uruguay, but Palmarito-equivalent beds (which do not overlap with Itaituba-equivalents) are not nearly so ubiqui- tous. None has been noted in cratonic areas north of southern Brazil. Parts of the Passa Dois Series of Ar- gentina contain Permian marine strata (Frakes et al., 1969) but their associated faunas, closely associated with glacial deposits, are clearly of Boreal affinities. Palmarito-equivalent strata are widely but system- atically distributed in the Western Hemisphere. Pre- Mesozoic continental configurations may have been such as to place some now separate localities relative- ly closer together. It is tempting to think that such pre- drift configuration hypotheses might be tested using faunal diversity data, but present analytic refinements cannot sufficiently reduce the noise level in the data. The new hypotheses do, however, aid in explanation of the great similarity in faunal composition found in many of the faunas within the Western Hemisphere marine Permian, because their present great latitudinal spread is most likely a Mesozoic artifact brought about by continental plate movements. HISTORICAL SETTING The first investigator to consider the relatively un- deformed Paleozoic strata of the Venezuelan Andes in detail was Christ (1927), who reported on the geo- logic section exposed along the trail from Mucuchachi to Santa Barbara de Barinas (Text-fig. 1). Christ di- vided strata of from Archaean to Tertiary age into six series. Of these, only three, the Mucupati, Palmarito and Lomita Series, are pertinent here. Christ sent the Palmarito Series fossils to the museum at Basle, Switzerland, where they were studied and later reported on by Gerth (in Gerth and Krausel, 1931). Specimens referred to Fusulina and Spirifer were the only ones described and illustrated, a dubious dis- tinction which they have, with a single exception (Hoover, 1975), maintained to the present day. Gerth (p. 524) recognized the presence of silicified fossils (“‘teilweise verkieselte Fossilien’’) in the unit, but nev- er mentioned that these might provide a better sam- pling of the fossil fauna. He concluded that, on the basis of correlations with Bolivia and Asia, the Pal- marito Series could not be younger than Late Carbon- iferous. Englemann (1935) cited three more Palmarito local- ities along the Transandean highway in the state of Tachira, but contributed nothing further to the stratig- raphy, lithology or paleontology of the unit. Schuchert (1935) reviewed work on the unit to date and con- curred in the view that it was of Late Carboniferous age. Hedberg and Sass (1937) dedicated a single two- line sentence to the presence of fusulinids in a lime- stone in the upper reaches of the Rio Palmar, Zulia PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 11 state. This appears to have been the first mention of possible Palmarito equivalents in the Sierra de Perija. In the following year a dispute began which con- fused the picture of the Venezuelan Upper Paleozoic for several years. The Palmarito in the type section was both under- and overlain by coarser-grained red- dish sedimentary rocks. The only fossils commonly found in either of these sandy units were in the lime- stone cobbles that locally formed a basal conglomerate within the overlying Lomita Series. Fusulinids, com- mon in these cobbles, may have been the basis for Christ’s assignment of a questionable Permian age to the bottom of the Lomita Series. The lithologic simi- larity of the Mucupati and Lomita Series made the Palmarito Series easy to identify (the only non-redbed) in the type area, but also, in this area where strati- graphically continuous exposures were exceptional, it encouraged confusion of the sandy units. This may be what started the controversy over the age of the Mucupati Series. Kehrer (1938) collected in the type area of the Palmarito and Mucupati Series in the 1930’s. During this trip he collected fossils from ‘“‘various localities in the sandstones within Christ’s Mucupati Series.’’ A poorly preserved molluscan fau- na indicated to him and to Kehrer, “‘Cretaceous . . . rather than Devonian age for the Mucupati Series.” (Kehrer, 1938, p. 50) Oppenheim (1937) complicated the situation by sup- porting Kehrer’s age for the Mucupati and renaming this Cretaceous unit the Sabaneta Group. Christ’s Lo- mita Series became the “‘Red Formations,” hardly a distinctive name in that area, and one which happily has not been repeated in the literature. To these units he assigned a Lower Jurassic to Cretaceous age. He had apparently not known the exact details of Keh- rer’s work, because he based the post-Paleozoic age of his Sabaneta Group on the absence of diagnostic Paleozoic marine fossils and on the presence of plant remains. Ktindig (1938) mentioned Kehrer’s ideas about the Cretaceous age of the Mucupati Series, “‘in- officially [sic.] called the Sabaneta Group,”’ but cited (p. 29) an exposure of the Palmarito Series that showed transitional contact with his underlying Sa- baneta Series (=Mucupati of Christ, 1927). Because no definite locality for Kehrer’s collections was given, and no lithic data other than that cited above was available, the problem probably can never be completely resolved. The existence in such a tec- tonically complex region as the type area of the Pal- marito of a fault sliver of a much younger, lithologi- cally similar unit, surrounded by Sabaneta strata, is a distinct possibility. Alberding (1956) may have settled the Mucupati/Sabaneta controversy by suggesting that the term “‘Mucupati’’ be considered invalid, since in the literature it consisted of at least two units of dis- tinct ages, in fault contact. Because it had originally been considered Devonian (Christ, 1927), and has re- cently been shown to be of Carboniferous and Permian (Pierce et al., 1961) as well as Cretaceous (Aguar- diente and Tomon Formations of Sutton, 1946) age, its stratigraphic utility was indeed compromised. Kehrer (1938) presented a suite of fossils from the Palmarito Series that had been collected along a new trail between Palmarito and Sabaneta. He inferred that there was a high probability that a large portion of the Palmarito in the type area was of Permian age, perhaps extending down into the Late Carboniferous in its low- er portions. Kehrer noted the great similarity of the Sabaneta to the Giron Series (an apparent equivalent to Christ’s Lomita Series, introduced by Hettner, 1892). He assigned an Early Carboniferous age to the Sabaneta. Schaub (1944) mentioned the occurrence of fusulin- ids of ‘“‘schwagerinoid”’ type in loose blocks of lime- stone that formed part of the basal conglomerate of the La Quinta Formation and described them as hav- ing been derived from the Palmarito Formation. In his opinion, the wall structure of the fusulinids indicated Middle Pennsylvanian to Permian age. The Upper Paleozoic in Venezuela is not confined to the Mérida Andes. Liddle (1946), in his book on the geology of Venezuela and Trinidad, included the sec- ond major review article on the Palmarito. He dis- cussed in detail work he had done along the Rio Ca- chiri in the Sierra de Perija (state of Zulia). There he described a section about 500 m thick, principally mi- caceous shales and sandstones, with a basal conglom- erate. The uppermost 17 to 25 m of this section was reddish-stained dark limestone, containing crinoid co- lumnals, Rhombopora or Alveolites, and an uniden- tified spiriferoid brachiopod. He assigned the section to the “‘Upper Permian”’ and correlated it with the Palmarito Formation of the Mérida Andes. The age of this unit is still in question, because the locality is difficult to pinpoint, and because field relationships in the Sierra de Perija are far from clear. Gonzales de Juana (1951) suggested that only the uppermost red- dish limestone should be attributed to the Palmarito, and that the rest of the sequence was better referred to as a Sabaneta equivalent (of Permocarboniferous age). De Rivero (1956) suggested that the redbeds might represent the La Quinta Formation, in fault con- tact with the overlying Palmarito Limestone, as sug- gested by the presence of limestone blocks in the basal conglomerate of the redbeds. Hea and Whitman (1960) also placed this portion within the La Quinta Forma- tion. Liddle mentioned as indirect evidence of the presence of Permocarboniferous in the Sierra de Pe- rija, float containing Dictyoclostus liddlei Harris, in the Cano del Oeste of the Rio Cachiri, and fusulinids in the upper reaches of the Cano Pescado, an affluent of the Rio Palmar. The former is not referable to any Palmarito dictyoclostid genus, and probably is not of Permian age. The fusulinids may have been the same as those mentioned by Hedberg and Sass (1937). Sutton (1946) discussed the Palmarito of the type area in the Mérida Andes, and measured the thickness of the unit as 1800 m. He did not, however, differen- tiate the Sabaneta from the Palmarito, which explains the great thickness given. Thompson and Miller (1949) described fusulinids and cephalopods from both the Palmarito and apparent time-equivalent strata in Colombia. These were ap- parently the same units, though in different localities, as those described by Trumpy (1943) from Colombia. Gonzales de Juana (1951) formalized the formational status of the Palmarito, and designated outcrops of sparsely fossiliferous dark limestones near the city of Mérida (state of Mérida) as Palmarito equivalents. From some of his samples from that area, Sellier de Civrieux (1951) identified, in association with Para- fusulina, a species of the foraminiferan Globivalvuli- na, which he considered most similar to forms from the Upper Guadalupian of West Texas. Pierce et al. (1961) discussed eleven marine fossil- iferous Paleozoic localities from the southeastern sec- tor of the Mérida Andes. Though most of these were already in the literature, all were enhanced by the de- tailed attention given them. Most localities were in structurally deformed areas, and although the fauna recovered in any single place was usually smaller than that in the relatively undeformed type area, the com- bined faunal listing is both impressive, and suspect. On the bases of fusulinid and other faunal evidence, the age of the unit is from mid-Pennsylvanian to early Late Permian. Measured sections yielded formational thicknesses from 200 to about 1200 m. The only sec- tion other than those in the type region from which a diverse Palmarito fauna was reported was the Carache area in the state of Trujillo. Shell and Creole (1964) mentioned the Palmarito Formation in a long article dealing mainly with older units in the Mérida Andes. They did not take issue with previous conclusions about the age or extent of the Palmarito, but did mention that on the basis of palynological investigations, the Sabaneta Formation was largely of Permian age, with only the lower part of possible Carboniferous age. Arnold (1966) described the Sabaneta sequence 2 BULLETIN 313 from several localities in the Mérida Andes. He de- tailed the lithologic characters observed in all sections, and arrived at age assignments that do not disagree materially with those of previous investigators. Exten- sive faunal lists given for three localities are based on samples taken in connection with the measurement and detailed description of stratigraphic sections. Shagam and Hargraves (1970), in an investigation of Permocarboniferous redbeds (Sabaneta and Mérida facies) in the Mérida Andes, considered the Sabaneta to underlie the Palmarito in its entirety, rather than contacting it diachronously, as had been suggested by Arnold. This concept was discussed further by Sha- gam (1972). Interest in the Palmarito over the last decade has not been centered on its faunal composition, but rather on its precise stratigraphic relationships and correla- tions, as these relate to the Paleozoic and subsequent development of the Andean region. At present there are two opposed hypotheses concerning Paleozoic sedimentation in this region. One, proposed by Arnold (in Shell and Creole, 1964; Arnold, 1966) suggested that Paleozoic sedimentation there occurred in two time periods, separated by a period of uplift, non-de- position and some deformation. The first of these sed- imentary cycles he called the Lower Paleozoic cycle, which included the deposition of the Caparo Forma- tion and its northern lateral equivalent, the Mucu- chachi Formation, in Ordovician and early Silurian time. Unconformably overlying these, the Permocar- boniferous continental Sabaneta Formation and its lat- eral shelf facies equivalent, the Palmarito, were de- posited. The opposing hypothesis of W. R. Smith (in Shell and Creole, 1964; see also Shagam, 1968; Martin B., 1968; Shagam and Hargraves, 1970; Shagam, 1972) showed a lower Paleozoic sedimentation cycle during which the Caparo, El Horno and Mireles Formations, among others, were deposited. This episode was fol- lowed by emergence during the Devonian and Missis- sippian. A second Paleozoic sedimentation cycle, roughly within the same basin, included the Mérida, Mucuchachi and Sabaneta facies, lateral equivalents of roughly the same age, overlain by the northern and southern facies of the Palmarito Formation, with the intervening basinal facies of Palmarito-equivalent age missing. These two models differ mostly in the age assign- ment of the Mucuchachi Formation, a sparsely fossil- iferous sequence of shales, phyllites and slates. In the latter explanation the Palmarito southern facies covers a longer time span than does the northern, implying a transgression of the Palmarito marine environment PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 13 from south to north, during Late Pennsylvanian time. It also shows a short hiatus within the Palmarito sec- tion in the south, and between the Palmarito and Mé- rida facies in the north, representing a period of non- deposition and (or) erosion, near the Pennsylvanian— Permian boundary. The concept of the Palmarito Formation has under- gone remarkably little alteration since Christ’s first formal description, while the section around it has been considerably changed. This is probably due to several causes. The type area of the formation is re- mote, and few direct observations have been made since 1927. Fossils are considered to provide an ob- jective means of determining relative position in a time scale, and while the Palmarito is replete with well-pre- served fossils, with two exceptions (Gerth and Krau- sel, 1931; Hoover, 1975), none have ever been de- scribed and figured. Thus, the real affinities of the fossils remain poorly understood. The Palmarito is lithologically conspicuous, as it is naturally defined by under- and overlying redbed units. In other areas it is less distinctive lithologically, but can be recognized easily when fossils are present. To field geologists working in the Mérida Andes, recovery of fusulinids indicates the presence of the Palmarito Formation. The extrapolation of this philosophy to the other mac- rofossils found in association with the fusulinids has led to problems in correlation, especially with the Per- mocarboniferous units exposed in the Sierra de Perija. Typical Palmarito shelf faunas have not been reported, to my knowledge, from the Venezuelan portion of the Sierra de Perija. That units of a similar age do exist close by in Colombia has been established by fusulinid and cephalopod evidence. BIOSTRATIGRAPHIC CORRELATION No attempt at biostratigraphic correlation of the Pal- marito fossil fauna with non-Western Hemisphere Tethyan Permian faunas is here attempted. The simi- larity of the Venezuelan forms to those from West Texas is so striking that more far-reaching correlation would in essence be a global correlation of West Texas rather than Venezuelan forms; an exercise of dubious significance, considering the comprehensive works on this subject already presented by others (e.g., Cooper and Grant, 1972; Grant and Cooper, 1973). The brachiopod fauna of the Palmarito Formation includes at least 32 genera and 44 species, of which 3 genera, 12 species and a single subspecies are de- scribed here as new. The names used in classification of these taxa are drawn from study of the available literature, but lean heavily on a recent monograph on the West Texas brachiopods (Cooper and Grant, 1972, 1974, 1975, 1976a, 1976b, 1977). This seems justified by the following: (1) Grant and Cooper (1973) have demonstrated the existence of trans-longitudinal ‘‘pro- vinciality’’ in the Upper Permian: regions within which correlation is enhanced and between which cor- relation is difficult. There is no reason to doubt that such divisions extend lower in the section. (2) The West Texas sections appear to be the most continuous and accessible expanse of Permian strata in the West- ern Hemisphere, and are considered the standard for the hemispherical marine Permian. (3) The diverse fauna recovered there during the past hundred or more years of study can better elucidate age and facies re- lationships of the Palmarito Formation than can geo- graphically closer, yet less well understood faunas in Central and South America, such as the Copacabana Group of Peru and Bolivia (Newell, Chronic, ef al., 1953; Samtleben, 1971) and the Chochal of southeast- ern Mexico, Guatemala and British Honduras (Stehli and Grant, 1970; Kling, 1960). Because my study was primarily faunal in emphasis, sampling localities were selected to (1) lie within the lithologically-defined boundaries of the Palmarito For- mation and (2) contain a high concentration of re- coverable fossils, preferably silicified. Low on the list of priorities (and probabilities) was knowledge of the exact stratigraphic position of a sample within a mea- sured section. The collection area has been mapped ona small scale, and at least one stratigraphic section has been competently measured in the vicinity of the type section (Arnold, 1966), but the mapping is sche- matic, and the section offers few recognizable land- marks for use in sample location. The true stratigraph- ic position of individual samples can rarely be determined in the field. Although it has been stressed (Grant and Cooper, 1973) that age determinations should ideally be made on the basis of the entire preserved fauna, only the brachiopods are extensively employed here. The bio- stratigraphic significance of the remainder of the fauna is dealt with briefly at the end of this section. As a first step in correlation, the brachiopod genera of the Palmarito Formation were compared with those recovered from each of several of the well-defined stratigraphic units of West Texas. Data for the latter were derived from Cooper and Grant (1972, 1974, 1975, 1976a, 1976b, 1977) and from collections at the National Museum of Natural History (Washington, D.C.). The Otsuka Coefficient* was used as a standard * The number of items (genera) shared by the two units com- pared, divided by the square root of the product of the number of items in each unit. 14 BULLETIN 313 of comparison, because it appears to reduce the bias inherent in comparing samples of different sizes (for discussion of the various binary coefficients which might have been employed, and their attributes, see Cheetham and Hazel, 1969). The use of the genus as a standard in this and following comparisons for cor- relative purposes follows the rationale of Grant and Cooper (1973, p. 573). The results of the above com- parison appear in Table 2. This shows that although all similarity levels are low, the highest level of simi- larity lies between the Palmarito Formation and the Road Canyon and Cathedral Mountain Formations of West Texas. In Table 1, one can readily appreciate the great dif- ference in brachiopod generic composition between Locality 6 and all other Palmarito Formation localities. This suggested the desirability of determining how many distinctive generic assemblages of brachiopods existed within the Palmarito Formation. To do this I calculated the similarity in generic composition of bra- chiopod assemblages at sampled localities within the Palmarito, and then systematically compared these groups with brachiopod assemblages from finer strati- graphic subdivisions in the better-known West Texas region. Again using the Otsuka Coefficient, the genera recovered at each locality were compared to those from every other locality, and the results were plotted as a similarity matrix (Text-fig. 2). While this matrix contains all the information needed to determine the degree of similarity among the localities, it lacks visual a ae Text-figure 2.—Similarity coefficient matrix for brachiopod gen- era in Palmarito Formation fossil assemblages. Large numbers rep- resent localities; smaller numbers are Otsuka Coefficient x 100. Table 1.—Occurrences of brachiopod genera in Palmarito For- mation fossil assemblages. x = presence; — = absence. Localities Genera LQ Bin 4a Se 164 To 8 LOPS Acosarina x Anaptychius x Anemonaria DX x Aneuthelasma x Chonetinetes x x x Cleiothyridina - -—- X =- = = = = = = = Collemataria x Composita Cooperina x Costicrura x Derbyia =—= xX X = X Dyoros x — = Echinauris ES ax See Holotricharina x Hustedia x x x Kutorginella a a Meekella - -—- XK K = = Neophricadothyris xX - =- = = = Neospirifer XxX - —- X - = Oligothyrina x x Paucispinifera x Peniculauris x x Petrocrania x Pontisia x x7 Ds Ramavectus = Rugatia X = Spinifrons - - Spiriferellina Stauromata X= =| X =| = KO eee Texarina x Xenosteges x Total Genera 10° 19) 11 a 10 SiS yeni oees x xX X &X Di XS Xo OX eX | | xX X [Se eoxXerares aos | | x | | x x x x xX X &X Table 2.—Comparison of brachiopod generic composition of the Palmarito Formation and of selected Permian biostratigraphic units in the West Texas region. Values are expressed as Otsuka Coef- ficient x 100; N = total number of genera included in given bio- stratigraphic unit. Palmarito Forma- tion, all localities [N = 31] Capitan and Bell Canyon Fms. (Guadalupian) 29 incl. all mbrs. [N = 73] Cherry Canyon, Getaway & Word Fms., 32 incl. all mbrs. (Lower Guadalupian) [N = 81] Road Canyon Fm. (Upper Leonardian) 41 [N = 88] Cathedral Mountain Fm. (Leonardian) 38 [N = 83] Skinner Ranch, Taylor Ranch, Hueco and Hess Fms. 33 (Upper Wolfcampian) [N = 81] PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 15 -100 - Text-figure 3—Dendrogram showing similarities in brachiopod generic composition among Palmarito Formation fossil assemblages. Figure derived by weighted-pair grouping of similarity coefficient matrix shown in Text-figure 2. clarity. To overcome this problem, the matrix was ‘clustered,’ using the weighted-pair grouping method (Bonham-Carter, 1967; Text-fig. 3). The limitations of the method employed, which include an imposition of hierarchal structure on the data, and the lesser signif- icance of clustering when the units compared (locali- ties) consist of small numbers of items (genera) (Stehli and Wells, 1971), have been recognized, and are con- sidered balanced by the more immediate visual intel- ligibility provided by the dendrogram. To appreciate the distortion imposed on the similarity matrix at low levels of association, it should be noted, by comparing Table 1 and Text-figure 3, that while localities 2 and 5 consist of a single genus each, locality 5 appears more similar to most others than does locality 6, which contains ten genera. From the dendrogram, four localities or groups of localities were selected to be used as units for further comparisons. The first group included localities 1, 4, 7, 8, 10 and 11: the second, third and fourth groups were localities 3, 13 and 6, respectively. Localities 2 and 5 were not considered because of the negligible fauna recovered. The four Palmarito groups were compared to six stratigraphic entities in the West Tex- as region (Table 3). While most of the similarity of Palmarito brachiopods to Lower and Middle Leonar- dian Texas forms comes from the first group, that group’s closest association is with the Road Canyon Formation fauna. The closest associations of the other three groups are with West Texas strata younger than Road Canyon: localities 3 and 6 with the Willis Ranch Member of the Word Formation and locality 13 with the Road Canyon Formation and the China Tank Member of the Word Formation. 16 BULLETIN 313 The brachiopod fauna as a whole (Table 7) has large- ly Late Leonardian or Early Guadalupian affinities. This is in strange contrast to the faunal aspect pre- sented by Arnold (1966); based on identifications by H. M. Muir-Wood (Table 4). My own reassessment of the brachiopod genera present in this collection (Table 4) is strikingly different, and profoundly affects the apparent familial composition of that suite (see dis- cussion under ‘‘Permian Ratio’’). Arnold stated (p. 2378) that Dr. Muir-Wood had indicated the age of the unit to be Early Permian. A comparison of the genera she reported with those from several West Texas stratigraphic units, again using the Otsuka Coefficient, showed the greatest faunal similarity with the Udde- nites-bearing shale zone that lies at the base of the Wolfcampian Series (Hoover, 1976a, pp. 61, 127). Brachiopods, though more intensively studied in this report, do not constitute the entire Palmarito fossil fauna. The other fossils recovered include bryozoans, cephalopods, chitons, corals, crinoids, echinoids, fu- sulinids, gastropods, ostracods, pelecypods, sponges and trilobites. These elements were forwarded to qual- ified workers for examination. The bryozoans, chi- tons, corals, crinoids, echinoids, ostracods and sponges present no more diagnostic stratigraphic in- formation than terms ranging from ‘‘Upper Paleozoic”’ to “‘Lower Permian,” but center about the latter de- gree of refinement. Cephalopods were recovered from several of the Palmarito localities sampled. Drs. Furnish and Glen- ister, of the University of Iowa, and one of their stu- dents, Dr. Chunsun Lee, kindly identified various coiled nautiloids from locality 1, and orthocone nau- tiloids like Mooreoceras from several localities. Of greater biostratigraphic importance, however, were the identification of Perrinites hilli at locality 4, and another locality (Field No. PRH-71-VE-12) nearby. This form was described by Miller and Williams (1945) from the Perija Peninsula of Colombia, and is similar to specimens from the Chochal Limestone in Guate- mala (collected by F. G. Stehli) and in Chiapas, Mex- ico (collected by Millereid). A Late Leonardian age is most likely for the deposits containing this form. Lee (1975) has identified (at loc. 10) Martoceras sub- interrupta, a form previously reported only from the Upper Artinskian [Baigendzhinian] of the Urals, roughly equivalent in age to the Cathedral Mountain Formation of West Texas (Waterhouse and Piyasin, 1970). Evidence from the fusulinids (Douglass, pers. comm., 1975) tends to support these ages. Fusulinids were recovered from two localities in the Palmarito: one, a short but indeterminate distance down section from locality 4, and the other from locality 6. Those Table 3.—Comparison of brachiopod generic composition of Pal- marito Formation fossil assemblages and (or) assemblage groups, with West Texas stratigraphic units. Values expressed are Otsuka Coefficient x 100; N = total number of genera included. Palmarito Formation Fossil Assemblages 1,4,7,8 10 & 11 3 13 6 [N=20] [N=9] [N=8] [N=10] Word Formation 24 22 19 25 Appel Ranch Mbr. [N = 56] Word Formation 28 23 19 26 Limestone Lens between Willis Ranch and Appel Ranch Mbrs. [N = 53] Word Formation 25 25 18 28 Willis Ranch Mbr. [N = 63] Word Formation 26 21 23 20 China Tank Mbr. [N = 62] Road Canyon Formation 38 721 23 20 [N = 88] Cathedral Mountain 34 22 19 21 Formation [N = 83] from the former locality were similar to Parafusulina durhami, and to Schwagerina setum, but differ from the latter in their larger proloculus and the presence of cuniculi. These characters suggest a Leonardian age for rocks at that locality. Those from locality 6 proved to be a new species of Parafusulina, similar to P. sellardsi, but slightly less advanced than that form, and indicative of latest Leonardian or possibly earliest Wordian age. Most of the gastropods (Yochelson, pers. comm., 1975) indicated an age of Late Pennsylvanian or Perm- ian, but one, Cylicioscapha, from locality 11, is typical of rocks equivalent in age to the Road Canyon or Word Formations of West Texas. The pelecypods appear North American in aspect, and one, Schizodus canalis, which appears at Pal- marito localities 1 and 8, appears elsewhere only in Road Canyon Formation age-equivalents, supporting a latest Leonardian age for the lower portions of the Palmarito (Newell, pers. comm., 1975). Trilobite fragments recovered from localities 10 and 13 were identified (Chamberlain, pers. comm., 1975) as species of Anisopyge, which appears in the Leo- nardian and Guadalupian of North and Central Amer- ica. In summary, most of the biostratigraphic indicators recovered point to a Late Leonardian or earliest Gua-_| PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 17 dalupian (Roadian to Wordian World Stage of Grant and Cooper, 1973) age, though there are indications (fusulinids and ammonites) that locality 10 may be somewhat older (Baigendzhinian World Stage of Grant and Cooper, 1973). LITHIC AND FAUNAL ANALYSIS INTRODUCTION All localities from which fossils were collected for this study were visited during July 1971 and April 1973. All lie within, or in close proximity to the type section of the Palmarito Formation, in the Arzobispo Chacon district of the state of Mérida, Republic of Venezuela (Text-fig. 1). Lithic Description Techniques Due to the variety of rock types collected, several methods of lithic description were employed. All rocks were described in the field, and the usual field char- acteristics noted. These included geographic and stratigraphic position, where these could be deter- mined, thickness and attitude of beds, color, gross mineralogy and bedding characters, fossil content and extent of exposure or outcrop. At localities 1 and 2 no further description was possible, since the rock was so friable that it could not be transported intact to the laboratory. A slab approximately 0.5 cm thick was cut from rocks taken from localities 3, 4, 5, 6 (block C), 7, 8, 10, 11 and 13. The plane of the cut was oriented normal to bedding if the latter could be ascertained. Both sides of the slabs were polished and X-rayed. The X-radiographs were used as aids in the determi- nation of depositional texture. The slabs, oiled or wet- ted, were also examined with a binocular microscope. Where possible (locs. 3, 4, 5, 6 (block C), 7, 10, 11 and 13) a representative chip (approximately 1 x 2 cm) of each rock type was made into a doubly-polished thin section, using the techniques of Moreland (1968). These sections, used in determinations of microstruc- ture, mineralogy and depositional texture, were ex- amined with a standard petrographic microscope. The slides were also analyzed by X-ray diffraction, to de- termine approximately the relative proportions of cal- cite, dolomite and quartz present. Rocks containing silicified brachiopod fauna were subjected to a rock constituent analysis to test correlation of lithic and paleoenvironmental parameters. Results were sum- marized by Hoover (1976b). A by-product of the anal- ysis was the discovery that the dark color of many of the rock samples was due to hydrocarbon infiltration. When the samples were dissolved large oil slicks formed on the liquid and container surfaces and the Table 4.—Genera and families of Arnold collection Palmarito Formation brachiopods identified by H. M. Muir-Wood and P. R. Hoover. Familial assignments follow the usage of the Treatise (Wil- liams et al., 1965). See Hoover (1976a) for more detailed identifi- cations. Genera Identified by H. M. Muir-Wood Family Assignment Meekella vis terete Meekellidae EISSOGHONCLESMR CE ae Chonetidae INQGAPOWAED. soscconsseceoonas Chonetidae Quadrochonetes .............. Chonetidae AVONIG Whine. whe naar ae Overtoniidae WAM ATE coscseocosneoodD us Marginiferidae E.Ghinaurismereer renee eee Marginiferidae Kozlowskiaienccrcreenince Marginiferidae Productus rere ener Productidae Bathy my OniGuaree eerie Echinoconchidae Waagenoconcha ............. Echinoconchidae YUTESANIG” Fete e centers eae Buxtoniidae Aritiqualoniaaey- ria Dictyoclostidae Reniculaurisae. cee eee Dictyoclostidae FRU GOH oie co ais jeje itovateersiaree nets Dictyoclostidae MNMIAAT: Sonbonssuado00o00D Dictyoclostidae ‘Cancrinella a ene ene Linoproductidae UStediat Peper neki eee Retziidae COMmpoOsitaies Stine es Ge Athyrididae INeospiniferns Hosmer Spiriferidae Phricodothyrisi suerte Elythidae I DHALIKY ead Ooo aOR OOO So oe Dielasmatidae Genera Identified by P. R. Hoover Family Assignment Meekellan C205 sheen einis sera Meekellidae Dy Ors: -ti5,50): 6 Aneuthelasma globosum 1s Sp. os. see eee ee eee eee 24 Cooperina inexpectata Termier, Termier, and Pajaud ........ 13 Costicruraiminuta ms gens andispy =... 2-. 42-2 e eee 6 Hustediathyporhachisimsps ... 42-5 «+ 2221 2- eeeeeee 4 Rhynchonellacea, family uncertain......................05- 2 XCHOSLESESWIMINUSCULUS Mn SPieaiedsncicl-isiee keene 5 BRYOZOANS indeterminate ramose and fenestellid forms CORALS indeterminate solitary rugose forms FUSULINACEANS (RCD) Parafusulina cf. P. sellardsi GASTROPODS (ELY) Orthonema sp. Platyworthenia sp. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER DS New genus aff. Taosia New genus of high-spired gastropods PELECYPODS (NDN) Pegmavalvula cf. gloveri Newell and Boyd SPONGES (JKR) Defordia cf densa Finks Guadalupia cf. williamsi King VERMES (ELY) two or more forms of Spirorbis or similar attached worm tubes BLock C BRACHIOPODS FAA DIY CHIUS MINUTUS Me/SeNs ANd SPs .c.c wo oe occre sarees 21 mAneuthelasma globOSuMm MN. SPs w:- yee) < 101s. 0 esters oie) 2 212 s/eyels he 38 Cooperina inexpectata Termier, Termier, and Pajaud ........ 99 MOsncr uy ayninulaan fen: and Speen ince ce cciecicieis ees ee 30 BIEL DNIGES D earete roe ays tosey sists fey ois, sie one ekovanis eps: oyoseis @88 vee en eles 1 Hchinauris bella Cooper and Grant ..................-:-..- 1 BTESECALCYILY D OFLA CHISUTICIS) sueestets eieeevedai oi. oiaceelevs es. Facies ole) oe 20 fmetrocrania teretis Cooper and Grant .....5.....22..500:--.- 2 Rhynchonellacea, family uncertain......................... 4 MCHOSTE SESIIMINUSCHUIUSIM: ISP s/s a)o eins a) eyaicl sis eie,ie sees oe cide 130 BRYOZOA indeterminate ramose and fenestellid forms CoRALS indeterminate solitary rugose corals small fragment of tabulate coral ?Acaciapora sp. (CTS) GASTROPODS (ELY) 2Orthonema sp. indet. Holopeiform gastropod indet. New genus of high-spired gastropods Pleurotomariacean gastropod indet. OsTRACODS (IGS) Cavellina? sp. Hollinella sp. Roundyella sp. indeterminate bairdiids PELECYPODS (NDN) Acanthopecten sp. Girtypecten sp. SPONGES (JKR) Defordia cf. densa Finks VERMES (ELY) two or more forms of Spirorbis or similar attached worm tubes Although the faunules recovered from the three blocks at locality 6 are similar, they are not identical. Numbers of brachiopod individuals probably better reflect intensity of picking of the acid-insoluble resi- dues than real diversity: relative numbers of individ- uals within the faunules may be more significant. All three blocks contain faunas that are largely adapted to life on a hard substrate. The tiny Costicrura is similar to Cruricella Grant (1976) from Thailand. Grant (1976, pp. 189-190) suggests that that small pediculate form lived closely appressed to a hard substrate, so closely indeed that in order to open its valves it would have had to relax its pedicle. When solidly fixed, beaks of both valves would have been in contact with the sub- strate, making shell gape impossible. Costicrura may well have shared this habit. Certainly it is found only in association with extensive hard substrates such as those provided by the sponge Defordia. Few free-liv- ing brachiopods are present in the assemblages. Only those generally conceded to be among the hardiest of Tethyan forms (e.g., Hustedia) lived on the soft sub- strate in this assemblage, and most others adapted to that substrate were probably derived from outside. Most of the brachiopods lived above the sea floor, attached to sponges. The three blocks sampled at lo- cality 6 probably represent three microenvironments within a larger incipiently biohermal environment. Block A is best characterized by the presence of the lyttoniid Collemataria, which appears nowhere else in the Palmarito Formation. Block B contains numer- ous specimens of Parafusulina, which is absent from both blocks A and C. Block C is characterized by the pelecypods Acanthopecten and Girtypecten, rather than Pegmavalvula, which appears in the other two blocks. The basic substrate is apparently the same in all three places: a soft substrate of biomicrite upon which sponges and clams have provided a secondarily hard surface. It would be tempting to suggest that a factor like salinity, energy, or depth differences was responsible for these apparently discontinuous distri- butions, but it is more likely to have been a complex combination of such factors. It is likely that the three microenvironments were contemporaneous and later- ally discontinuous, patterns that are reflected in ver- tical section. The fine calcareous biomicrite that forms the basic soft substrate here probably settled out when moderately strong currents struck such effective baf- fles as the fenestellid bryozoans and anastomosing sponges. These currents were probably the agent that produced the asymmetrical valve distributions (Text- fig. 4) in all but the most tightly articulated forms (e.g., Anaptychius). The environment of deposition is inter- preted to have been in shallow, warm water, of mod- 26 BULLETIN 313 erate current activity. The lack of noticeable amounts of terrigenous material suggests that it was not near a shoreline of high relief. It appears to have been in a less restricted area than that represented by locality 3, as it lacks the dolomite rhombs so prevalent there. Locality 7 was a paving stone in the mule trail be- tween Palo Quemado and Mucuchachi, about 1 km northwest of Palo Quemado, and about 200 m toward Palo Quemado from the small chapel locally known as Capilla de la Santa Cruz de Palmarito (Text-fig. 1). This is on the old trail connecting Mucuchachi and Santa Barbara de Barinas, and the locality lies within the type section of the Palmarito Formation as defined by Christ (1927). Although out of place there, the rock sampled is definitely from within the formation. The outcrop from which it was derived, however, could not be located. The block was about one m square and one-fourth m thick, and consisted of a dark gray, pet- roliferous, fossiliferous, fissile, very silty limestone. Field examination using dilute HCl discovered no silicified fossils, but crackouts were so promising that a large amount of material (almost the entire block) was collected. Preparation was entirely by mechanical methods. In thin-section and polished slab examina- tions, the rock proved to be heavily infiltrated by hy- drocarbons that probably accounted for most of its dark color. Within the sand and silt fractions there was primitive sorting, and some thin graded beds (on the scale of the thin-section), but in general the rock was poorly sorted. Compositionally a biomicrite, it con- tained large numbers of apparent sponge spicules and abundant angular skeletal and quartz grains and rock fragments scattered through the micritic groundmass. The rock showed signs of having suffered soft-sedi- ment deformation: laminar fine sediments draping over clasts, crushing normal to bedding, and considerable apparent recrystallization and welding at intergranular boundaries had taken place. In terms of depositional texture the rock is a packstone. Few brachiopods showed an asymmetrical valve distribution (Text-fig. 4). Among the fossils recovered from this locality were: BRACHIOPODS PACOSATIMANES Dae inie cern ere er acini taietetcrecn ter accuser ts l Composita cf. C. pilula Cooper and Grant ...............--. 6 Echinauris cf. E. liumbona Cooper and Grant .............. 93 Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 1 MeckellaiskencoidesaGuty. ner eieaeciaiekeieciateni leer: 1 Neophricadothyris cf. N. crassibecca Cooper and Grant ..... 150 Neospirifer venezuelensis (Gerth) ...............scseeseeees 16 Rugatia occidentalis (Newberry) .........2 000 cece eee e ee ees I Stauromataves CLericamn. CEN sand iSP ete: eyetetervanne et neler ats 16 BRYOZOA indeterminate fenestellids CORALS (CTS) Lophophyllidium sp. ECHINODERMS columnals Although there is some disarticulation of the fossil brachiopod shells recovered at locality 7, the large percentage of fine micritic matrix seems to indicate that the environment of deposition was one of rela- tively low current energy. Most of the breakage or distortion of shells observed can be attributed to soft- sediment deformation, probably due to sedimentary loading. Shells are not severely abraded: both primary and secondary layers of most shells can be discerned in thin-section. The abundance of angular quartz and rock fragments suggests that the depositional environ- ment was close to a shoreline of moderate relief, in shallow, warm water. Locality 8 lies in the side wall of the mule trail con- necting Palo Quemado and Mucuchachi, about 200 m toward Mucuchachi from a small chapel locally known as Capilla de la Santa Cruz de Palmarito (Text-fig. 1). This is on the old Santa Barbara de Barinas—Mucu- chachi mule trail, within the type section of the Pal- marito Formation as defined by Christ (1927). The vol- ume sampled here was about one-half cubic m. The rock at this locality had been totally leached of soluble carbonates to a depth of over one m, so that although the rock would texturally be a wackestone, or in com- positional terms a biomicrite, it contained no calcite or dolomite. Fossils from this strange matrix were re- covered in surface collections and by cutting them from the dried silt residues with the aid of dental tools | and an S. S. White Airbrasive unit. Most specimens were silicified, but many leached calcareous individ- uals left beautifully detailed molds. These were col- — lected if they represented rare forms or added signif- icant features to those taxa represented by silicified specimens. In addition to the fossils, numerous large — bodies (up to 10 cm in largest diameter) of consoli- | dated sediment, with thin silicified rinds, occurred — commonly within the surrounding finer laminar sedi- — ments. Pinching and compression of these finer lami- | nae was probably due to loading either by these large | clasts themselves, or by the accumulated sediment j column, while the sediments were still relatively plas- | tic. Among the fossils recovered were: | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 27 BRACHIOPODS Chonetinetes cf. C. varians Cooper and Grant .............. 3 Composita cf. C. pilula Cooper and Grant ................. 76 ‘DASE CDA BATE OS s.b 6 space OE CRD GOUEr a UtOe OOD De SHED oT.C l Derbyia cf. D. complicata Cooper and Grant ............... 4 Echinauris cf. E. liumbona Cooper and Grant .............. 11 Holotricharina hirsuta Cooper and Grant .................-- 4 DMG VOTED OSS copo.chinn sosanierdadopdapsooeanecoood 1 LEMS CGH Os sooericls bodn.c0 0b DEORIOCOOR Ee HC On mt Oba tc Meret ] Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 16 Wieekellaiskenoides | GIIty’< .fjsi2 fo ieae «oss erence Sis sss. 01sieieee peieieceys 3 Neophricadothyris cf. N. crassibecca Cooper and Grant..... 42 Neospirifer venezuelensis (Gerth) ...............0.220eeeee 1 Paucispinifera? cf. P. sulcata Cooper and Grant ........... 4 Pontisiasstenlit) Cooper and! Grant; 3. 4..22.6 0-22 +25-+ ones nec 6 INE UCT TAIN Goa sobba cosa shaeLouees Ganon onOo aoe 30 BUF LOTSA CIAIGOST ANN SP eiayelator-vonesausyeleiet oooh 2i- ctr kel eustsiose 4 Stauromata esoterica n. gen. and sp. ..........2.-.02-e0e es 3 BRYOZOA indeterminate ramose and fenestellid forms CORALS (CTS) Lophophyllidium sp. aff. L. spinosum Jeffords ECHINODERMS indeterminate cidaroid (echinoid) spines and plates (PMK) columnals GASTROPODS (ELY) Kinishbia sp. Meekospira sp. indet. Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic New genus allied to Orthonema PELECYPODS (NDN) Schizodus canalis Branson SPONGES (JKR) indeterminate sponges Soft sediment deformation in the rock at locality 8 was probably quite minor, and limited to that occur- ring below the large bodies that are here interpreted as storm-derived rip-up clasts. Most shell breakage observed can be explained by either or both transpor- tation and abrasion near the site of deposition (Text- fig. 4). The only brachiopods at all well preserved are those (e.g., Neophricadothyris, Composita, Derbyia) that appear to be adapted to life on a soft substrate. Many of the valves of Neophricadothyris however, consist solely of beaks, suggesting that the more fra- gile portions of the valves were abraded away. High energy pre-depositional current or wave activity must be invoked to account for the condition of these fos- sils. The environment of deposition is inferred to have been in shallow, warm water near wave base, in an area affected by periodic storms. Locality 10 is situated along the mule trail that con- nects El Portachuelo and Palo Quemado (Text-fig. 1). The rock is exposed in and on both sides of the trail itself, about 100 m south of the house locally known as ‘Altamira’ (owned in 1971 by Silvestre Gutiérrez). Although several m in extent, this exposure is prob- ably a large exotic block, as most surrounding rocks are reddish and greenish sandstones referable to the Sabaneta Formation. The block itself consists of rath- er thin (S—15 cm thick) beds of a slightly silty dark gray limestone, separated by thinner (ca. 1 cm thick) partings of gray siltstone. The collection area covered about two m laterally and one m normal to bedding. Both lithologies are abundantly fossiliferous. Domi- nant forms recognized in the field are the brachiopods Hustedia and Derbyia. These fossils and many others are finely silicified, and were prepared for study by etching in dilute hydrochloric acid and removal of the dried decalcified silt residues with an S. S. White Air- brasive unit. Some of the globular forms (e.g., Hus- tedia) contained silicified laminar geopetal structures. Some cephalopods, gastropods and pelecypods were preserved as apparent silicified micrite envelopes. In thin-section and polished slab the rock is clearly a biomicrite, with occasional thin bands of fine sandy material. The shells do not appear to have been com- pacted by soft-sediment deformation, and although the rock is grain-supported in places, it contains a consid- erable percentage of mud. In terms of depositional tex- ture it is a wackestone. Some shell breakage occurred as a result of decalcification during etching of crack- fillings of tectonic origin. Among the fossils recovered were: BRACHIOPODS ANEMONGTIa SUDIGEVISA (SINE) aes ae cerca 29 Composita cf. C. pilula Cooper and Grant ................. 5 Derbyiadeltaunicilataanespa reer eer ree erecta eeeer 34 Holotricharinat spy Av aamecet ctrl: anita ¥reeeaaree 1 Hustediathyporhachishnaspyeereeeee ee eee eee eee eS) Pontisiasstehiis Coopemand) Grantee -eere ee ee eoere ee eerere 4 Rhynchonellaceay familyuncertainiys.-eee eee eee ae eee 5 Rugatiaintermediawns Spence dao eens eee eee 1 BRYOZOA indeterminate ramose and fenestellid forms “Lyropora”’ sp. CEPHALOPODS Mooreoceras-like orthocone nautiloid (WMF; BFG) Martoceras subinterrupta (Krotov, 1885) (CSL) 28 BULLETIN 313 CORALS (CTS) Lophophyllidium sp. cf. L. pelaeum (Jeffords) ?Acaciapora sp. ECHINODERMS columnals GASTROPODS (ELY) ?Ananias sp. indet. Apachella sp. indet. Bellerophon sp. indet. Euphemites aequisulcatus H. Chronic Euphemites cf. E. exquisitus Yochelson Glyptospira sp. indet. Kinishbia sp. Naticopsis sp. indet. (2 subgenera) Onycochilus sp. indet. Orthonema sp. Retispira sp. indet. “Soleniscus’> sp. indet. Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic Worthenia sp. indet. New genus of high-spired gastropods New genus of high-spired gastropods with changing spire angle PELECYPODS (NDN) Pseudomonotis sp. Sanguinolites sp. TRILOBITES (CKC) Anisopyge perannulata (Shumard) Girty, 1909 The shells from this locality have suffered very little from post-depositional soft substrate deformation. The dark color of the rock, like that of most Palmarito lithologies, is due to interstitial infiltration by hydro- carbons that is clearly secondary. Although there is some breakage and separation of the easily disarticu- lated productids, the extremely delicate dorsal valves of such forms as Anemonaria are often preserved in their entirety (Text-fig. 4). This suggests that current activity was not strong in or near the depositional en- vironment, and that the assemblage is mostly a bio- coenose. The attitude of many fossils (e.g., Derbyia, Hustedia, Lophophyllidium) suggests that this locality represents at least in part an only slightly disturbed living assemblage. The fossil assemblage consists en- tirely of forms adapted to life on muddy substrates, and there are no cemented forms. The presence of geographically widespread nektonic forms (the ceph- alopod Martoceras subinterrupta and the Mooreocer- as-like orthocone nautiloid) suggests that there was access to the holomarine environment, and that local- ity 10 lay offshore from any local reef-like develop- ment. Most specimens of the paucispiniferid Anemo- naria were recovered during the etching of a single small block. This is interpreted to indicate that the spatial distribution of such forms was discontinuous and patchy, since postmortem transport would have entailed more breakage and wear than is observed in these delicate forms. Derbyia too seems patchily dis- tributed, but not in so clear cut a manner as Anemona- ria. Specimens of Hustedia appear discontinuously distributed as well: some individuals of both it and Derbyia are markedly atypical or asymmetrical, indi- cating growth in dense populations, yet some blocks collected contain few individuals of either. The diver- sity of gastropod types and the presence of trilobite remains suggest a vigorous infauna whose bioturba- tory activities may have contributed to some of the valve fragmentation observed. The environment of deposition, and for most of the organisms preserved, the life environment, is interpreted as having been in shallow, warm water below wave base, on a soft mud- dy bottom, with clear access to open ocean, and rel- atively far offshore. Locality 11 consists of several exotic blocks lying up a steep slope from a disused mule trail that connects the small settlhements of El Portachuelo and Santa Rosa (Text-fig. 1). It lies on the west flank of the Que- brada Palmar, near the head of that stream. The rocks are repeated intercalations of thin- to medium-bedded, dense, dark gray, petroliferous fossiliferous silty lime- stones and thinner, fossil-poor calcareous siltstones. The contacts between limestone and siltstone are somewhat undulatory but are persistent as far as they can be traced (tens of m in some of the largest blocks). There are two distinct lithic types within the limestone itself, which are revealed in thin-section and polished slab: one is a relatively unfossiliferous biomicrite, which is poorly sorted and in places laminar; the other is a very fossiliferous muddy calcarenite, and textur- ally is locally either a packstone or grainstone. Most of the clasts in both rock types are skeletal in origin: those in the grainstone are considerably more rounded and abraded. The fossils recovered were all silicified, many of them imperfectly. Silicified micrite envelope casts of chiton plates, cephalopods, gastropods, and pelecypods are common. The assemblage was pre- pared for study by etching in dilute hydrochloric acid, and subsequent removal of the dried silt residues using hand tools and an S. S. White Airbrasive unit. The asymmetry of valve distributions and general condi- tion of the fossils indicates that there had been con- siderable taphonomic abrasion, if not transportation. Among the fossils recovered were: PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 29 BRACHIOPODS Anemonaria? cf. A. sublaevis (King) ...........2-0200e005> 4 Composita cf. C. pilula Cooper and Grant ...............-- 6 Derbyia cf. D. filosa Cooper and Grant .................5-- 9 Echinauris cf. E. lappacea Cooper and Grant............... 20 NOE ARS hws ep adaoncopae ono boDmoooobmod aDcopoMe 1 PIUSICAICNILY POF RACHISAN ESD ease tier-t-\- ate steteveterasierc ict ners sera 43 Kutorginella cf. K. umbonata (Muir-Wood and Cooper) ..... 5 MEE KEN CASKenoid ess GiltVecrteiesy-/-\sarciteislvors tere siorchtele e etelets crcl 1 PoniusiaysteniinGooper and Grant \-)1-)- tse << ieteli< oie eteler al 17 Rhamnariidae cf. Ramavectus Sp. .......... 0 cece eee eens 1 THEO THONEAHOMG SisccosenoddesseeoosuouobbadonDoDDDO 4 Spinifrons? cf. S. grandicosta n. Sp. ... 1.00... e cece eee 7 MEXATING ACen WOrGeNsis) (KING) = yers ee ale sees eles eins ee 5 BRYOZOA indeterminate ramose and fenestellid types CEPHALOPODS (WMF; BFG) Mooreoceras-like orthocone nautiloid CHITONS (AGS) indeterminate chiton plates CORALS (CTS) Lophophyllidium sp. ECHINODERMS columnals GASTROPODS (ELY) Anomphalus sp. indet. Apachella aff. A. franciscana (Chronic) Apachella sp. “Colpites”’’ sp. indet. Cylicioscapha sp. Glyptotomaria sp. indet. Glyptospira sp. indet. holopeiform gastropod indet. Kinishbia sp. ?Meekospira sp. indet. Onycochilus sp. indet. Orthonema sp. Straparollus (Euomphalus) aff. S. (E.) kaibabensis H. Chronic Taosia sp. new genus aff. Taosia new genus allied to Orthonema new genus of high-spired gastropods open-coiled vermitiform pleurotomariacean, genus new PELECYPODS (NDN) Astartella sp. Aviculopecten sp. Guizhoupecten sp. Nuculopsis sp. Parallelodon sp. Pegmavalvula cf. gloveri Newell and Boyd Pseudomonotis sp. Pseudopermophorus sp. Sanguinolites sp. Streblochondria sp. SPONGES (JKR) Colospongia sp. Cystothalamia sp. (nov.?) Defordia cf. densa Finks Girtyocoelia sp. Haplistion cf. H. aeluroglossa Finks, 1960 hexactinellid root tuft Wewokella (?) sp. Most specimens of the diverse fauna recovered from this locality come from the relatively thin packstone- grainstone layers, which consist almost entirely of se- verely abraded skeletal fragments. Far less worn, bro- ken or abraded shells are found outside of these layers: the faunal composition of the muddier portions is es- sentially the same as that in the packstones, but fossils are far less abundant. This suggests that the more fos- sil-rich layers are simply localized concentrations de- rived from the same environment, the result of pe- riodically elevated energy conditions. The silty layers that intervene between the limestones, however, are almost barren of fossils, and contain only an occa- sional Hustedia or Composita, brachiopods that are almost ubiquitous in the Palmarito (Text-fig. 4). These siltstone laminae are interpreted as fines that have been winnowed out of the packstone-grainstone lay- ers. The shells found in the siltstones are probably those generalist forms that first settled on the soft sub- strate when the energy regime had returned to lower levels. The fauna as preserved is one of the most diverse in the Palmarito, but no one element is dominant. It appears that most of the forms have been derived from another life environment and are here allochthonous. Although no rip-up clasts such as those seen at local- ities 4 and 8 were observed, some of the rocks seen here (the packstone-grainstone layers and siltstones) could be ascribed to the local winnowing action of periodic storms, which would segregate the skeletal debris and micritic matrix on the sea floor. Preserved portions of an apparently diverse assemblage of bio- turbators (chitons, gastropods, some pelecypods) may have aided in comminution of skeletal debris, but can- not be responsible for the sorting observed. The en- vironment of deposition is interpreted as having been in shallow, warm water, near wave base, over a soft substrate, in an area subject to periodic storms. Locality 13 consists of a large (ca. 100 kg) rounded exotic block which lay beside the mule trail connecting El Portachuelo and Mucuchachi, about 200 m toward 30 BULLETIN 313 El Portachuelo from locality 6 (Text-fig. 1). No expo- sures of similar rocks could be located on inspection of the surrounding area. The boulder showed no ob- vious bedding laminations, and was a dense, dark gray to black, petroliferous, silty limestone, without the siltstone partings common to most other samples col- lected in this study. In polished slab examination, there were suggestions of bedding along which hydro- carbon infiltration had proceeded. Thin-section ex- amination showed the rock to be compositionally a biomicrite, with dolomite rhombs in addition to skel- etal clasts, and in terms of depositional texture a wackestone. It had not been secondarily compacted as had many other Palmarito samples, and the fossils recovered from it were without exception exquisitely preserved by fine silicification (see Pl. 4, fig. 55). All recovered fossils were prepared by etching in dilute hydrochloric acid, and removing the small quantity of adherent silt residues using an S. S. White Airbrasive unit. Valve distributions of some easily disarticulated productaceans like Echinauris were markedly asym- metrical (Text-fig. 4). This may in part be explained by the comparative fragility of the dorsal valve in such forms. Most other valve distributions were symmet- rical. Among the fossils recovered were: BRACHIOPODS Chonetinetes cf. C. varians Cooper and Grant .............. 4 Composita cf. C. pilula Cooper and Grant ................. 8 DerbyiaiauripleXxdaneisp wert La irik ete 7 OEM Sos goossosene gob susbo po omnonooEbogbouEnAeSToEB Od 4 Echinaurisibella) Cooperand! Grant = eee se tere tere) -t=y-t)s 377 FET OLOTICRATINGESD WAG eect een senate tlaitret l Hustediavhyporhachisans Speanai ea eae eee ala 89 OligothyrinaQvgsp were esas AN Ie eee REN els 2 SH OOO GTA NCO SOs sbeooguccssced¢oonsccvconupod de 2 BRYOZOA indeterminate fenestellids CHITONS (AGS) indeterminate chiton plates CORALS indeterminate solitary rugose form GASTROPODS (ELY) Anomphalus sp. indet. Apachella sp. Discotropis sp. of Yochelson, 1960 cf. Donaldina sp. indet. Glabrocingulum sp. indet. Glyptospira sp. indet. Goniasma sp. one Goniasma sp. two Kinishbia sp. indet. Meekospira sp. indet. Naticopsis sp. (new subgenus) Orthonema sp. Taosia sp. ?Worthenia sp. indet. holopeiform gastropod indet. low-holopeiform gastropod open-coiled ?pleurotomariacean high-spired genus indet. new genus of high-spired gastropods sinistral gastropod indet. PELECYPODS (NDN) Sanguinolites sp. Pseudomonotis sp. TRILOBITES (CKC) Anisopyge ?inornata Girty (in Lee and Girty, 1909) The exquisite preservation of such delicate spinose forms as the Echinauris and Holotricharina here sug- gests that deposition took place under conditions most favorable for fine preservation (rapid burial in soft sed- iment, perhaps under reducing conditions). The lack of breakage by soft sediment compaction suggests that the rocks were deposited close to the end of Palmarito deposition, and that the overlying column of marine sediments was thin. The symmetric valve distribution (Text-fig. 4) of most faunal elements suggests that ta- phonomic alteration was minimal. The comparative fragility of the dorsal valve of the Echinauris easily explains the asymmetric distribution seen in that form. The ventral valve is protected from breakage by a for- est of spines that almost completely surrounds it. Muir-Wood and Cooper (1960, p. 45) suggested that some accumulations of marginiferids (like Echinauris here: see PI. 4, fig. 55), that included shells in almost every possible orientation, may have been biocoeno- ses. The spines covering the ventral valve hang over the commissure to such a great extent that the shell would have been supported above the soft substrate, and able to carry on life processes in clear water, in almost any position. It may be that the hollow, mantle- filled spines also served as springs to cushion the jars and blows encountered as the shells were rolled about the sea floor by currents. The comparatively large number of specimens of this form collected here is probably best explained by the manner in which the spines of Echinauris entangle one another. Obviously this sort of habit led to localized and discontinuous populations on the sea floor. Pre-lithification breakage of the entire fossil assemblage at this locality was mi- nor. The environment of deposition is interpreted as having been a soft-substrate bottom, with little relief, below wave base in warm water, perhaps restricted PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 3] from ready access to open ocean conditions. The pres- ence of chitons, gastropods, certain pelecypods and trilobites suggests the presence of an infauna that may in part have been responsible for any shell disarticu- lation that occurred. Bioturbation, if present (see Thayer, 1979), was extensive, as few traces of bedding laminae, and no burrows or feeding traces now re- main. DEPOSITIONAL ENVIRONMENTS Pierce et al. (1961) and Arnold (1966) have dem- onstrated that the Sabaneta and Palmarito Formations (or facies) are records of a marine transgression from southeast to northwest across the Mucuchachi depo- sitional basin in Permian time. The Sabaneta repre- sents the continental facies of this transgression and the Palmarito the marine facies. None of the rocks and fossils analyzed here indicate deposition in other than marine conditions, but some (locs. 3, 5 and 13) indicate that access to open ocean may have been restricted locally. Almost all the assemblages are characteristic of soft, muddy substrates. In only three (locs. 3, 5 and 6) are there indications of other conditions. In the en- vironment of locality 5, energy conditions were prob- ably too severe to allow settlement of attached forms on the winnowed calcarenite substrate, but at locali- ties 3 and 6, hard-bottom assemblages colonized sponge substrates. At locality 3, hypersaline condi- tions may have prevented optimal development of the full potential of brachiopod diversity provided by or- ganic hard substrates in the Tethyan realm. At locality 6, however, holomarine conditions were present, and greater diversity could develop. The faunal differences in the three samples from that locality are probably due to a variety of causes, notably the patchy distri- bution that is characteristic of tropical organisms. The periodic storms inferred from sediment characters in the Upper Palmarito Formation may have acted as environmental stresses deterrent to bioherm formation on the scale of those seen in the age-equivalent Ca- thedral Mountain and Road Canyon Formations of the West Texas region. ORGANISM/SUBSTRATE RELATIONSHIPS Stehli (1971) suggested that in tropical regions soft- substrate environments may act as a secondary stress, after temperature, limiting the distribution of some Permian Tethyan articulate brachiopods. One object of my study was to determine if there were some ob- jectively measurable parameter that could be related meaningfully to the character of the substrate on which these brachiopods lived. A measure of the size- frequency distribution of sedimentary particles was one logical possibility (Hoover, 1976b). The easily measured sand/silt ratio was not employed, since in the Palmarito the sand and coarser particles commonly are skeletal in origin, and are variably silicified. Some are lost in etching, so that the weight percent of re- coverable sand is meaningless as a measure of original sediment grain-size distribution. A potentially more useful parameter that appeared likely to remain intact through lithification and diagenesis was the ratio be- tween silt- and clay-sized particles in the hydrochloric acid-insoluble residues. The silt/clay ratio should re- flect substrate character as a partial record of the en- ergy regime and (or) current activity. A higher energy regime or episodic activity should leave a lithic record with a higher silt/clay ratio than that of a quiet envi- ronment or episode, since higher energies would pref- erentially remove the finer particles. The only Pal- marito rocks useful for such studies were those that contained appreciable numbers of silicified fossils. It was assumed that silicification equally affected all sizes of fine particles, so that the insoluble residues remaining after etching would reflect in a consistent way the size-distribution of the parent sediment. It was also assumed that originally non-carbonate fines were either minor, or had the same or similar size- frequency distributions as the calcareous sediments, and that the percentage of clay-sized particles agglom- erating to form silt-sized particles was approximately the same in both insoluble residues and parent sedi- ment. Much of the Palmarito is characterized by repeated intercalations of thin limestones and thinner shales. Where possible both lithic types were sampled at each collecting locality, and analyzed separately. Analytical techniques and calculations were discussed by Hoover (1976a). In most Palmarito localities an interesting result of the analysis was that shales had higher silt/clay ratios than the limestones they separated (see Table 5). Everywhere that this relationship held, the shales con- tained much less diverse brachiopod assemblages than did the limestones. In places where this relationship did not hold (locs. 6A and 10) the shale assemblage was equally as diverse as that of the surrounding lime- stone. The shales (assuming the silt/clay ratio does indeed reflect energy conditions) are thus interpreted as having been produced by the winnowing effect of localized higher energy conditions. The few fossils found within them are the most common forms (Hus- tedia and (or) Composita), which apparently either could live under rather harsh conditions, or were the first to resettle the free substrate when energy condi- tions returned to lower levels. The shale at localities 32 BULLETIN 313 6A and 10 is interpreted as the result of a change in sedimentation rate, rather than energy conditions, which would not change the size-distribution of the substrate grains or materially alter the habitat of the brachiopods that lived there. The intercalated lime- stones and shales of the Palmarito suggest a periodic- ity of such higher energy episodes. Ager (1974: Juras- sic of Morocco), Bowen, Rhoads, and McAlester (1974: Devonian of New York), and Bretsky and Bret- sky (1975: Ordovician of Quebec) noted similar de- posits and interpreted them as storm deposits. Tending to support this contention for the Palmarito are the apparent rip-up clasts seen in the limestones of assem- blages 4 and 8 (see ‘“‘Lithic and Faunal Analysis’). It was originally hoped that the silt/clay ratio might be correlated with brachiopod habitat type, which should in turn be controlled in part by substrate. To this end, the Palmarito brachiopod genera were sep- arated into three classes by habitat type: pediculate, free-living and cemented (Table 6). The percentage of the total bed assemblage in each class was calculated (for both species and individuals) and plotted on a tri- angular diagram (Text-fig. 5). The proper position of some genera in this admittedly simplistic division is p 25 Individuals Text-figure 5.—Habitat-type distributions for species and individ- uals in Palmarito Formation brachiopod assemblages. Localities are numbered. F = free-living, supported on soft substrate by spines or shell; P = attached to hard or soft substrate by functional pedicle; C = cemented or closely appressed to hard substrate; E = entire brachiopod fauna (all localities). Table 5.—Results of rock constituent analyses of Venezuelan marine Permian rocks containing appreciable numbers of silicified fossils. See Hoover (1976a) for discussion of calculations and ana- lytical techniques. L = limestone analysis; S = shale analysis; Rep. = replicate analysis. Percent Percent Local- Soluble Insoluble % Silt/ ity and Carbonate Inorganic % Clay Silt/Clay Gross and (sand- (insoluble Ratio Lithol- Organic size or and (by ogy Fraction coarser) inorganic) weight) 3, 91.9 6.7 0.9/0.5 1.86 35 49.9 48.8 1.0/0.3 3.73 4, qe 18.0 5.0/1.9 2.56 4, 66.5 253 6.6/1.6 4.64 Shy 97.5 0.5 1.1/0.9 ieil7/ 6A, 89.2 6.8 2.3/1.6 1.42 6A, (Rep.) 89.8 6.5 2.1/1.6 1.27 6As 70.6 17.9 6.9/4.6 1.50 6C,, 87.4 7.9 2.9/1.8 1.65 10, 87.9 Sy 4.0/2.8 1.43 10, 65.2 22.9 5.9/6.0 0.99 11, 87.0 10.3 1.8/0.9 1.90 iil 67.5 19.6 9.3/3.6 2.56 13) 94.9 1.3 PN 1.22 questionable. Schiimann (1969) has shown that many of the Orthotetacea, including such Palmarito forms as Meekella and Derbyia, were not cemented to the substrate but rather attached by a short byssus-like pedicle, which penetrated the ventral beak through | numerous tiny holes. These two genera are here ar- © bitrarily assigned to the pediculate class. Text-figure 5 emphasizes the difference in taxonom- ic and habitat-type composition between the incipi- — ently biohermal fauna at locality 6 and all others in the Palmarito. As can be seen by a comparison of the silt/ clay ratios (Table 5) and the habitat-type diagrams (Text-fig. 5), there is no correlation between the two. Within the variation attributable to experimental error (Hoover, 1976a), the silt/clay ratio of soft-bottom as- semblages such as locality 10 are identical to those from the demonstrably hard-bottom incipiently bio- hermal assemblages of locality 6. It is difficult to dif- ferentiate soft- from hard-bottom assemblages on se- dimentological grounds in carbonate rocks. It appears _ that, at least in the Palmarito, hard bottom assem- blages arise on soft substrates, by initial growth of populations of large sponges (e.g., Defordia sp.). These forms were able to grow, once established on | a comparatively small hard substrate such as a shell, | and to increase in size far beyond the margins of the | original attachment surface. They could grow out | along the surface of soft substrates and project upward | into the water column as well. They thus provided | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 33 Table 6.—Habitat-type classification of Palmarito Formation bra- chiopod genera. Pediculate = attached to the substrate by a func- tional pedicle during most or all of life; Cemented = anchored by ventral valve, ventral beak, or rhizoid spines, usually to some “‘hard’’ surface; Free = lying loose on the substrate, there sup- ported by the ventral valve, commonly also by specially oriented spines or processes. Pediculate Cemented Free Acosarina? Collemataria Anemonaria Anaptychius Cooperina Chonetinetes Aneuthelasma Petrocrania Dyoros Cleiothyridina Ramavectus? Echinauris Composita Xenosteges Holotricharina Costicrura Kutorginella Derbyia Paucispinifera? Hustedia Peniculauris Meekella Rugatia Neophricadothyris Spinifrons Neospirifer Stauromata Oligothyrina? Pontisia Spiriferellina Texarina? niches for several phyla of attached forms (including several families of endemic Tethyan brachiopods) which could not otherwise survive in a soft-substrate environment. Thus the hard-bottom niches that many of the Tethyan brachiopods occupy are not reflected by measurable parameters of the sediment grain-size frequency distribution, nor do these seem to correlate with the distribution of the sponges, which act to es- tablish greatly enlarged hard substrate areas. It is instructive to compare the thermally-based lat- itudinal distribution of Permian articulate brachiopods to their habitat types. The Road Canyon Formation of West Texas (roughly equivalent in age to the Palmarito {see Biostratigraphic Correlation]) contains 34 families of articulate brachiopods. Of these, 16 are globally cosmopolitan, while 18 are limited mostly to low lat- itudes. Slightly less than half of the cosmopolitan fam- ilies are adapted to life on a soft substrate, and no cemented forms are truly cosmopolitan in their Perm- ian distribution. Among the Tethyan endemic families, however, one-third are cemented in habitat-type, and only a single free-living family is represented (in the Road Canyon assemblages sampled). Thus the high familial diversities recorded in many Permian Tethyan fossil brachiopod assemblages reflect the presence of organic hard substrates that provided the necessary niche space for diversification. PERMIAN RATIO Stehli (1971, 1973) related the thermally-controlled latitudinal taxonomic diversity gradient to the distri- bution of families of thermally-tolerant cosmopolitan (Boreal and Austral) and thermally-sensitive endemic (Tethyan) Permian articulate brachiopods. He found 16 families that had been recovered from most Perm- ian brachiopod faunas, all over the world. These he designated Cosmopolitan Dominant families. They were (according to the classification used in the Trea- tise [Williams ef al., 1965]): the Schuchertellidae, Orthotetidae, Chonetidae, Marginiferidae, Echinocon- chidae, Buxtoniidae, Dictyoclostidae, Linopro- ductidae, Stenoscismatidae, Rhynchoporidae, Athy- rididae, Spiriferidae, Spiriferinidae, Bachythyrididae, Elythidae and Dielasmatidae (Stehli and Grant, 1971, p. 504). The difference between the number of families of Permian brachiopods recovered from a locality and the number of Cosmopolitan Dominant families re- covered there, divided by the latter number, Stehli termed the ‘‘Permian Ratio”’ for brachiopods (1970, p. 3330). This ratio was employed instead of pure diver- sity in discussions of latitudinal diversity variations, as it reduced somewhat the sampling bias inherent in some of the collections, and acted as a temperature- sensitive indicator. A value for the Permian Ratio was calculated for each known brachiopod fauna, and plot- ted against latitude (Stehli, Douglas and Newell, 1969, fig. 2; Stehli, 1970, fig. 16; Text-fig. 6). Recent latitudes are used in preference to any of several paleomagnet- ically-based paleolatitudinal frameworks, (1) to pro- vide direct comparison with relevant previous papers (e.g., Stehli, 1970), and (2) to avoid the controversy that would follow the use of any one of the paleomag- netic schemes currently in favor (cf. Habicht, 1979; Scotese et al., 1979). My usage of a recent latitudinal coordinate should in no way be construed as a denial of the sea-floor spreading and continental drift hy- potheses. Although there is considerable spread in the values, there is clearly a trend upward from the pole toward a maximum close to the present equator. The fauna of the Palmarito, as it was known prior to this study (i.e., from Arnold, 1966; Pierce et al., 1961), provided the data for point | in Text-figure 6. This fauna was not included in Stehli’s figures, as he had used only those which were described and fig- ured, so that he might personally ascertain familial assignments. It happened by chance that the speci- mens on which Arnold’s faunal list had been based came (via the identifier (Dr. H. M. Muir-Wood) and Dr. A. J. Boucot) to be in the collections of the Na- tional Museum in Washington, D.C. Dr. Muir-Wood’s identification labels still accompany the specimens. Conditions were thus ideal for a taxonomic re-evalu- ation of the fossils (Hoover, 1976a). Each identified brachiopod in the Arnold Collection 34 BULLETIN 313 PERMIAN 10 RATIO 80 70 60 50 40 30 LATITUDE O O @O Oy ee) O O O O O O SOUTH —— A —[P 20 10 (0) 10 20 30 40 Text-figure 6.—Permian Ratio for brachiopods, calculated for well-known localities of marine Permian fossils, plotted against latitude. Point @) represents the Palmarito fauna as reported by Arnold (1966); point @ represents that collection as re-examined herein; point ® represents the entire suite of Palmarito Formation brachiopods available for this study. Data were derived from Stehli, 1970; Samtleben, 1971; Stehli, pers. comm., 1973; this study. was re-examined and identified in the light of knowl- edge gained through study of my own collections. Considerable generic reassignment resulted (see Table 4) and a second, revised value for the Permian Ratio of the fauna was calculated, and plotted as point 2 of Text-figure 6. The classification used throughout this study is, at the family level, very close to that of Cooper and Grant (1972, 1974, 1975, 1976a, 1976b, 1977). In order that the Permian Ratio values calculated for the entire fauna might be comparable with those previously cal- culated, the taxa presented in this study were reas- signed at the family level, to accord with the Treatise classification (Table 7). This third value for the Perm- ian Ratio for Palmarito brachiopods is plotted as point 3 in Text-figure 6. One of the goals of this study was more rigorous definition of the inflection point of the curve in the plot of Permian Ratio vs. Latitude (see Text-fig. 6). The addition of two or three points to the curve cannot accomplish that. This portion of the study shows however, that the Permian Ratio of such tropical faunas as the Palmarito can be enhanced by more comprehensive collecting, and that the brachio- pod fauna, in terms of familial diversity, is Tethyan in character, and not temperate as had been suspected (Newell, pers. comm., 1972). I also wanted to determine the source of the dra- matic increase in the apparent taxonomic diversity of the Palmarito brachiopod fauna shown in Text-figure 6. Table 8 shows Permian Ratio values for both Dr. Muir-Wood’s and my own analyses of Arnold’s col- lections, as well as for individual collecting localities in the present study. It is striking that, of the twelve non- Cosmopolitan Dominant families in the entire fauna, eight are represented in a single locality (local- ity 6) and that only three of these appear elsewhere in the formation as presently known. Without the chance discovery of this block (which probably would not have been sampled in a normal stratigraphic study, as it is patently out of place and not located within a measurable stratigraphic section), the Permian Ratio value for the entire fauna would have been drastically reduced (see Table 8). PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER Table 7.—Familial affinities of Palmarito Formation brachiopod genera. Both the familial assignment used in the Systematic Pa- leontology section of this study and that used in the Treatise (Wil- liams et al., 1965) are given. [ ] surround the probable family as- signment of genera described since 1965. Inarticulate brachiopods (e.g., Petrocrania) are not used in calculation of Permian Ratio or Sampling Index. Family in Family in Genus this study Treatise Petrocrania ....... (QRINGES socdsasassee Craniidae Ascosarina? ....... Schizophoriidae ...... Enteletidae IDERDYIG) voc cme. oven DETDYIIGACw eilreciciers- Orthotetidae Meekella .......... Meekellidae ......... Meekellidae DN @O9. dapaocoobeue Rugosochonetidae .... Chonetidae Stauromata ....... Rugosochonetidae .... [Chonetidae] Chonetinetes ...... Rugosochonetidae ....[Chonetidae] Xenosteges ........ Aulostegidae ......... Aulostegidae (GOOPENING .5..0-2 65: Cooperinidae ........ [Strophalosiidae] Ramavectus? ...... Rhamnariidae ........ Buxtoniidae Echinaurus ........ Marginiferidae ....... Marginiferidae Echinoconchidae ... Echinoconchidae ..... Echinoconchidae Anemonaria ....... Paucispiniferidae ..... [Linoproductidae] Paucispinifera? . Paucispiniferidae ..... Linoproductidae Holotricharina ..... Linoproductidae ..... [Overtoniidae] Kutorginella ....... Retamidae™ peer eee Marginiferidae Peniculauris ....... Dictyoclostidae ...... Dictyoclostidae LTSEOVETE (50 ett RRR Dictyoclostidae ...... Dictyoclostidae SPIRO GI Saae oboe Dictyoclostidae ...... Dictyoclostidae Collemataria ...... leyttoniidael eeereeeec [Lyttoniidae] POTS Cat eteeetneee Pontisidae eeecesceeee [Wellerellidae] HIMSTCCIC sce... - RGWAERO soccadcopnes Retziidae Cleiothyridina ..... Athyrididae .......... Athyrididae Composita ........ Athyrididae .......... Athyrididae (COSGTTIGe! Sooo ueane Ambocoeliidae ....... [Ambocoeliidae] Neophricadothyris . Elythidae ............ Elythidae INGOSPIFIfEr ...---- +> SIMIC S socsscaces Spiriferidae Spiriferellina ...... Reticulariinidae ...... Spiriferinidae Aneuthelasma ..... Dielasmatidae ........ [Dielasmatidae] Oligothyrina? ...... Pseudodielasmatidae .. Labaiidae Anaptychius ....... Cryptonellidae ....... [Mutationellidae] WEXATING?) ..iviewic cs Cryptonellidae ....... (Cryptonellidae] SAMPLING EFFICIENCY INDEX Stehli (1970, p. 3327) and Stehli and Grant (1971, p. 504) presented as a rough measure of the efficiency of sampling (for Permian articulate brachiopods) the ratio of the number of Cosmopolitan Dominant families found, to the number expected (16). It is instructive to look at the sampling efficiency index (SEI) in com- bination with the Permian Ratio (PR), as they are closely related (see Text-fig. 7). This figure shows the poor sampling efficiency in the Palmarito relative to the intensively investigated (roughly age-equivalent) Road Canyon Formation of the West Texas region. A rough estimate of the advantage of silicification over calcareous permineralization as a mode of pres- ervation can be gained by looking at the SEI of oth- erwise similarly constituted assemblages in the Pal- >) n Table 8.—Permian Ratio and Sampling Efficiency Index of Pal- marito Formation articulate brachiopod assemblages. Families are assigned according to the Treatise classification (Williams ef al., 1965; see Table 7). Cosmo- politan Sam- Total Domi- pling Number nant Perm-_ Effi- of Fami- Fami- ian ciency Assemblages lies lies Ratio Index Arnold Collection (as identified by Muir-Wood) 14 10 0.40 0.63 Arnold Collection (as identified by Hoover) 12 9 0.33 0.56 locality 1 7 6 0.17 0.37 locality 2 1 1 0.00 0.06 locality 3 8 4 1.00 0.25 locality 4 7 6 0.17 0.37 locality 5 1 1 0.00 0.06 locality 6 11 3 2.67 0.18 locality 7 8 6 0.34 0.37 locality 8 12 8 0.50 0.50 locality 10 7 4 0.75 0.25 locality 11 11 6 0.83 0.37 locality 13 8 5 0.60 0.31 Entire Fauna 24 12 1.00 0.75 Entire Fauna 19 12 0.58 0.75 (less loc. 6) 30 r ] O, 2.04 @ e o ° 2 104 O; eek 8 ° a eaten St @ ‘ene 8 | PERMIAN 4 10 @ @ r RATIO é4 (e) e e r 13 e@ Q e 4 Og r 44 | O; Qy e 24 a, OE Pa pe RAO ERSOMMEEGOI UG70™ au aeEsO SAMPLING EFFICIENCY INDEX Text-figure 7—Permian Ratio and Sampling Efficiency Index for nine Palmarito Formation (Venezuela) and 35 Road Canyon For- mation (West Texas) articulate brachiopod assemblages. Open cir- cles = Palmarito Formation assemblages (numbered); solid cir- cles = Road Canyon Formation assemblages; A = Arnold collection as re-examined herein; B = entire Palmarito Formation collection; C = Palmarito Formation assemblages, except assemblage 6; D = 35 Road Canyon Formation assemblages. 36 BULLETIN 313 marito (Table 8; see ‘‘Biostratigraphic Correlation’’). While it should be noted that no one locality is very efficiently sampled, the maximum SEI attained by silicified assemblages, such as that at locality 8 (=0.50) is not equalled by the non-silicified assemblages (locs. 1 and 7 = 0.37), even though these were as diligently sampled (according to a subjective estimate of effort expended). For faunal sampling, the collection of large amounts of silicified faunas wherever found within a unit is superior (in terms of the SEI) to the strictly stratigraphic attack, where samples of all exposed rocks are taken in a single or several sections, but along as continuous exposures as possible. In addition to making collections of that sort, those interested in the biostratigraphic implications of a fauna might do well to make collections of promising float blocks. It has been demonstrated that the SEI obtained by a combination of these methods is superior to that ob- tained by using a single one (my collection total SEI = 0.75; Arnold’s collection total SEI [re-examined] = 0.56). Four Cosmopolitan Dominant Permian articulate brachiopod families were not identified in any of the Palmarito material available for study: the Schuchert- ellidae, Stenoscismatidae, Rhynchoporidae and Brachythyrididae. Rhynchopora, the only Permian rhynchoporid genus, was reported by Pierce et al. (1961) in the Carache area of the state of Trujillo, Ven- ezuela, but since neither specimens, illustrations nor descriptions were given, this occurrence cannot be considered valid data for this study. The inherent un- reliability of even generic identifications in faunal lists is emphasized not only by my re-examination of the Arnold Collection (Hoover, 1976a), but also the fact that, to most investigators, such a list is relatively use- less unless accompanied by the name of the person responsible for it. A few of the specimens from locality 6 that were assigned to ‘“‘Rhynchonellacea, family uncertain’’ bore some resemblance to stenoscismatids. There were, however, no preserved interiors, or vestiges of the anterolateral stolidium characteristic of the family, so that not even tentative assignment to that group could be made. The majority of the inferred substrates en- countered in the Palmarito (soft-bottom) are inter- preted as suitable for the establishment of populations of stenoscismatids, so that some other factor (resulting in nOn-occurrence, non-preservation or non-collec- tion) must be responsible for their absence. Although several small apparent juvenile orthote- taceans were found at localities 3, 4 and 6, only one appeared to exhibit the recurved erismata of the Schuchertellidae. The small size and coarse silicifi- cation of this single specimen, however, made even tentative assignment to that family unjustified. Several Tethyan brachythyridid genera are known in the Western Hemisphere, but their occurrence is almost entirely limited to North America. The family is known from other continents, however, and is wide- spread in the Boreal and Austral regions. Four genera are known in the West Texas region: Eliva, Elivina, Eridmatus and Spiriferella. Of these only Spiriferella occurs in rocks of an age thought to be equivalent to the Palmarito strata (Roadian) and there it occurs in only two of 34 localities surveyed. Perhaps, as Grant (1976) has suggested, connections with Boreal popu- lations of Spiriferella were closed at this time, pre- venting easy access to the south. In Mexico the genus is known from the Monos Formation, thought to be a time-equivalent of the Word Formation of West Texas (Cooper et al., 1953). It has not been recovered further south in the Americas, and it may be that it is not truly cosmopolitan in its distribution. There are several possible reasons for the apparent non-occurrence of certain Cosmopolitan Dominant families. Stehli and Grant (1971, p. 505, text-fig. 3; reproduced here in Text-fig. 8) note that the SEI de- creases southward across latitude, beginning this de- cline at about 30° North latitude. They suggest that this phenomenon may be due to “‘deeper tropical weathering, less intensive study and the increase of small, difficult to collect forms in the Tethyan assem- blage.”’ The first of these suggested reasons at least is not applicable to the Palmarito. Locality 8 consists of rocks so deeply weathered that although the limestone 1.005 (0), ©) O || eo (e) oO so, O (exe) (ojeye») ®@ OO S.E.1.4 oO Oo . 2. ® oO Co) oO | fe) 2 fe) Oo O oO ©) © 404 oO | ©) oO g 204 O UNORTAE T T a T T T T T T Tole ear Siew 90 60 30 0) 30 60 90 LATITUDE Text-figure 8.—Sampling Efficiency Index for Permian articulate — brachiopod assemblages, calculated for well-known collecting lo- calities, plotted against latitude. Point ® represents the Palmarito Formation brachiopod assemblage as reported by Arnold (1966); point @) represents that collection as re-evaluated herein; point @) represents the entire suite of Palmarito brachiopods available for study. Data from Stehli and Grant, 1971; this study. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 37 depositional fabric and texture remain intact, they contain no soluble carbonate whatsoever. Yet this lo- cality provided the highest SEI of any in the forma- tion, and was represented by the greatest number of brachiopod families. Some tiny forms may have been lost, but in the silty limestones so common in the ma- rine Permian of Central and South America, extensive natural leaching provides good opportunity for the for- mation of external and internal molds. At locality 8, some of the calcite in the specimens had been silic- ified, so that preservation is in the form of external and internal molds and silica replacements. Less intensive study is a real factor: many southern hemisphere exposures are not only relatively poorly exposed and remote, but are far from major study cen- ters. The high SEI’s reported to the north of 30° North probably reflect two things. The Boreal Permian bra- chipod fauna consists to a great extent of large, easily recovered, commonly preserved, massive forms, due to the proclivity (suggested by Stehli and Grant, 1971, p. 507) for such forms to be characterized by late ma- turity, slow growth and individual longevity, so that faunas composed largely of Cosmopolitan Dominant families could easily be fully sampled (16 out of 16). Tethyan faunas from the Boreal/Tethyan boundary down to about 30° North lie within the area where the great majority of persons interested in the study of such forms live, and (with the exception of Australia and New Zealand), the combination of good exposures and interested investigators is not present south of that latitude. Less intensive study may also be a result of the different modes of sampling, discussed above, which can significantly alter both the Permian Ratio and Sampling Efficiency Index. In contrast to Boreal or Austral ones, Tethyan as- semblages certainly do include smaller, more delicate forms. Collection of silicified assemblages, however, should (as in the Palmarito) allow recovery and rec- ognition of the tiniest, most delicate brachiopods (e.g., Costicrura minuta, loc. 6; see PI. 8, figs. 41, 44). There are other possibilities. Using the Palmarito as an example, we may compare assemblages from pres- ent-day tropical regions to those from temperate re- gions of the Western Hemisphere (West Texas). Against the nearly total exposure, moderately steeply- dipping beds and relatively high relief, and relatively easy access and short travel distance from research centers of the West Texas exposures, contrast the structurally complicated, vegetatively overgrown, dis- tant, relatively less accessible beds of equivalent age in Venezuela. It has been suggested (McCall, pers. comm., 1975) that the decline may be due to the equa- torward decrease in eurytopic forms. Bulk sampling and the use of the family as the taxonomic base should reduce a large part of such bias. Warme (1969) has remarked that “‘regardless of the geometry of spacing [of samples] it is unlikely that any sample of reasonable size will include all individual species living in a given [tropical] habitat.’’ This of course becomes less applicable at higher taxonomic levels until at the family level one should be able to sample all families present within a more modest sam- ple size. But what is this optimum sample size? Grant (1971) has shown that the number of species of silic- ified brachiopods identified in the Road Canyon For- mation of West Texas increased directly in proportion to the amount of rock collected. He unfortunately gives no data as to how much was collected from each locality, but has assured me (Grant, pers. comm., 1975) that the average exceeded the 50-100 kg range of samples from the Palmarito. In the Palmarito it was often impossible to sample even this much at a single locality, due to the logistics of removing and trans- porting that much material. Cooper (pers. comm., 1975) has remarked that in- dividual bioherms in the West Texas Permian tend to have highly individual fossil faunas at the species level, thus tending to support Warme’s contentions in the fossil record. In the Palmarito, only locality 6 could be considered as incipiently biohermal, as con- trasted to the commonness of these structures in the Road Canyon Formation, its closest West Texas cor- relative (see ‘‘Biostratigraphic Correlation’’). I sus- pect many more as yet uncollected such deposits may exist within the Palmarito exposures. The chance, however, of collecting all such deposits is smaller than that of collecting all types of biostromes or incipient bioherms in a more accessible, better exposed situa- tion. Thus the second of Stehli and Grant’s suggested reasons for lowered sampling efficiency in the south- ern hemisphere is probably largely responsible for that decline. Although such a decline is reversible, through intensive work and a more faunally-oriented sampling program (see Text-fig. 8, points 1, 2 & 3), it is ques- tionable whether that reversal would ever become fi- nancially or physically feasible. INTRODUCTION TO SYSTEMATIC PALEONTOLOGY PHILOSOPHICAL CONSIDERATIONS The concept of the species, the basic unit of tax- onomy, has been succinctly defined, for living organ- isms, in terms of reproductive capability. In the fossil 38 BULLETIN 313 record, however, our frequent inability to distinguish individual time planes confidently in the rocks often means that rather than dealing with contemporaneous distinct species, we are concerned with variably-sized segments of evolving lineages. Since evolution, whether it moves gradually or in a saltatory fashion, is a process in which both organisms and their inter- relationships change, the species concept becomes in- creasingly abstract as our power of time-resolution decreases. The most common unit of sampling in the fossil record is the formation. Shaw (1964), among many others, has demonstrated that formation bound- aries may be diachronous, and that the distribution of fossils within such a unit is not necessarily isochron- ous. Inherent in the common belief that in paleontol- ogy we are indeed dealing with organisms divisible into species analogous to biological species, is the as- sumption that the evolutionary change taking place in a lithic unit or units is small: our gauge of this change is, and must be morphologically based. The paleontologist today would normally concede that he (she) tries in some measure to think of the fossils he studies as once-living organisms. This be- comes a basic problem in classification: should one attempt somehow to approximate the range of varia- tion implied in the biological species concept, or should one describe and differentiate morphological variants? In the case of the Permian brachiopods one might think there would be little choice. A vast ma- jority of these organisms represent stocks that have no modern representatives. Soft parts are rarely pre- served and their form is rarely indicated. Yet the ax- iom of the working paleontologist to “‘think of fossils as once-living organisms’’ leads us to infer soft parts to clothe these partial skeletons. One possible solution to this problem would be to give strictly morphologically-based taxa special sorts of names. This has been done in the study of mio- spores and ichnofossils, but, although desirable, it seems an impractical solution to the problem faced by the invertebrate paleontologist. Brachiopods exhibit homeomorphy to a great de- gree, i.e., a Mississippian and a Permian productid brachiopod, or two geographically distant Permian brachiopods may exhibit strikingly similar external or internal characters. The inter-relationships of paleon- tology and biostratigraphic and evolutionary studies, however, may require that such forms be given dis- tinct names that have more temporal and spatial than morphological foundations (for a fuller discussion of this problem, see [among others] Bell, 1950). In sum, a morphological classification would be sim- pler in terms of describing objects, if no further use was to be made of them. We cannot do this because we do envision inferential uses of fossils. We thus make the apparently valid assumption that forms suf- ficiently separated in time cannot represent close ge- netic relatives (because this might suggest retrograde evolution within a lineage, and we assume that exact retrograde evolution is highly unlikely) and that the conspecificity of geographically distant forms is sus- pect. A practical justification of this assumption is bio- stratigraphy. Genera or species with large gaps in their temporal distributions are biostratigraphically trouble- some. At any time, only a limited number of brachiopod morphologies can exist in the niches available. Tem- poral homeomorphs, while a systematic and biostrati- graphic problem, can be useful in making paleoeco- logical inferences, as the they may imply adaptation of (assumed) different stocks to similar environmental conditions. Morphospecies, at least species of Permian brachio- pods described here, have different ranges of varia- tion. In the “‘Comparison”’ sections following, each species is carefully differentiated from others in its genus, to justify its claim of morphologic uniqueness. A more important reason for this intellectual exercise is to show how closely one form may be morpholog- ically (and, by inference, genetically) related to another. Species names are simply handles for convenient discussion of time segments of evolving lineages. More often than not, real evolutionary significance lies with groups of several, rather than single species. As — an entire lineage becomes better understood, specific names as such become less significant or necessary. FORMAT In general the taxonomic hierarchy above the family level is simply stated, and generally follows the clas- sification scheme of Cooper and Grant (1972, 1974, 1975, 1976a, 1976b, 1977). Simple diagnoses of families and subfamilies are considered sufficient here. De- tailed generic descriptions are included only for new taxa. Individual species are always considered in de- — tail. TERMINOLOGY The jargon words peculiar to brachiopod systemat- | ics, as for any other descriptive art, are numerous, | and hopefully more precise than the word-combina- | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 39 tions they replace. Those used here follow Muir- Wood and Cooper (1960), the Treatise (Williams et al., 1965) and the recent monographic study of the West Texas Permian brachiopods (Cooper and Grant, 1972, 1974, 1975, 1976a, 1976b, 1977). TYPE REPOSITORIES The initials of the type repositories cited in the fol- lowing text are explained below: USNM = National Museum of Natural History, Smithsonian Institution Washington, D.C. 20560, U.S.A. MMH = Ministerio de Minas e Hidrocarburos (now Ministerio de Energia) Direccion de Geologia Caracas, Venezuela NMB = _ Natiirhistorisches Museum Basel Basel, Switzerland MEASUREMENTS The measurements of the brachiopods presented in the following section are standard except where oth- erwise defined, and follow the usage of Muir-Wood and Cooper (1960, pp. 18-20). In the tables of mea- surements, various subscripts have been employed as qualifications: b = broken: Used where the shell is broken at one or both extremities of a linear measurement. Unless further qualified, measurements so marked should not be taken as typical. c = crushed: Used where complex breaks and (or) obvious distortions of the shell, not explainable in terms of the organism’s life processes, have occurred. Unless further qualified, measurements so marked should be considered atypical. e = estimated: Used when the author has estimated the measurement, based on reasonable restoration of breakage, crushing or other distortion. h = half-measurement: Used in the measurement of bilaterally symmetrical features (e.g., hinge width of a productid) when one extremity is damaged. The measurement made is one-half that given in the table. BRACHIOPOD SYSTEMATIC PALEONTOLOGY Phylum BRACHIOPODA Dumeril, 1806 Class INARTICULATA Huxley, 1869 Order ACROTRETIDA Kuhn, 1949 Suborder CRANIIDINA Waagen, 1885 Superfamily CRANIACEA Menke, 1828 Family CRANIIDAE Menke, 1828 Discussion.—The Craniidae are the only inarticulate brachiopods that are commonly recovered by the hy- drochloric acid etching technique. Their original cal- citic composition probably accounts for their silicifi- cation in common with the articulates. Genus PETROCRANIA Raymond, 1911 Diagnosis.— Attached, pedicle valve thin; brachial valve conical, ornament of concentric growth lines, in some simulating ornament of host; char- acterized by pair of sigmoidal dorsal vascula lateralia, secondary canals branching off laterally; posterior adductors larger than an- terior, margin of valves not thickened. (Rowell, 1965, p. H290) Type Species.—Craniella meduanensis Oehlert, 1888, p. 102. Occurrence.—Petrocrania has been recovered from rocks ranging in age from Middle Ordovician through Permian in Europe, North America and Asia. It is un- common in the Permian, but this is probably in part due to lack of both interest and recognition. Comparison.—Among Permian Craniidae, Petro- crania differs from Crania Retzius (1781) and Phil- hedra Koken (1889) which bear ornament of radial costellae, Lepidocrania Cooper and Grant (1974), which bears strongly lamellose concentric ornament with rare spines, and Acanthocrania Williams (1943), which bears a roughly radial ornament of short spines, in its nearly smooth ornament of concentric growth lines. Discussion.—The inarticulate brachiopods play a very small part in the total brachiopod fauna in the Upper Paleozoic. One reason they are overlooked is that their stratigraphic range is commonly great: as biostratigraphic indicators they are comparatively poor. Petrocrania teretis Cooper and Grant Plate 1, figures 1-6 Petrocrania teretis Cooper and Grant, 1974, p. 250, pl. 28, figs. 17— 25. Description.— Small, smooth, variable cones with rounded sides and anterior: posterior side usually straight. Cones varying from nearly flat to high and misshapen, usually low; beak off center, from one-third to two-fifths of length from posterior margin. Posterior slope gentle; median region somewhat swollen and having steeper sides than the long anterior slope. Surface smooth except for slight irregularities inherited from host. Anterior adductor scars larger than posterior adductors which are marginal. (Cooper and Grant, 1974, p. 250) 40 BULLETIN 313 Measurements (in mm).— Thick- Length Width ness LOCALITY 6, BLOCK A: USNM 220974 (dorsal valve) Detke DPT 0.7 USNM 220975 (dorsal valve) 3h5) 38) 1.2 USNM 220976 (dorsal valve) 3.8 4.0 é MMH-DG-501 (dorsal valve) 4.2 4.6 1.2 USNM 220977 (dorsal valve) 4.5 4.7 1.0 USNM 220978 (dorsal valve) 5.6 6.2 0.32, LOCALITY 6, BLOCK C: USNM 220979 (articulated valves) 3.3 3% USNM 220980 (articulated valves) 4.3 4.5 165 Occurrence.—Petrocrania teretis Cooper and Grant occurs in the West Texas region where it was first described from the Cherry Canyon and Word For- mations of Early Guadalupian age. In the Palmarito Formation it has been recovered in the assemblages at locality 6, blocks A and C, where it is rare. An Early Guadalupian age for these Palmarito assem- blages is not inconsistent with other biostratigraphic indicators. Diagnosis.—Small, subcircular, depressed conical Petrocrania. Types.—Figured Specimens: USNM 220975, USNM 220979; Measured Specimens: USNM 220974-220980, MMH-DG-501. Comparison.—P. teretis may be distinguished from P. diabloensis Cooper and Grant (1974) and P. exas- perata Cooper and Grant (1974) by its smaller size, and from P. septifera Cooper and Grant (1974) by its lack of a dorsal median septum. The vascula lateralia, said by Rowell (1965, p. H290) to characterize the ge- nus, cannot be discerned in either Venezuelan or West Texas individuals referred to P. teretis. Discussion.—In contrast to the long ranges and con- sequent stratigraphic uselessness of many of the in- articulate brachiopods, P. teretis appears to be easily recognized by its small size and smooth exterior, and is comparatively restricted in its time range. The spec- imens recovered from block C of locality 6 (USNM 220979, USNM 280980) consist of articulated valves. Although this is the first occurrence of a Petrocrania ventral valve in the Western Hemisphere, its signifi- cance is minor since the conjoined valves cannot readily be separated. Material.— Articu- Ven- lated Dorsal tral Type of Locality Valves Valves Valves Preservation 6 (block A) — 11 — fine silicification 6 (block C) 2 — — fine silicification Class ARTICULATA Huxley, 1869 Order ORTHIDA Schuchert and Cooper, 1932 Suborder ORTHIDINA Schuchert and Cooper, 1932 Superfamily ENTELETACEA Waagen, 1884 Family SCHIZOPHORITIDAE Schuchert and Levene, 1929 Genus ACOSARINA Cooper and Grant, 1969 Type Species.—Acosarina dorsisulcata Cooper and Grant, 1969, p. 2, pl. 5, figs. 19-23. Diagnosis.—Small Schizophoriidae with rectimar- ginate to sulcate anterior commissure and low ventral median septum. Occurrence.—Acosarina has been recovered in the West Texas region alone, in beds ranging in age from latest Pennsylvanian (Gaptank Fm.) to Guadalupian (Word Fm.). It is likely that its geographic range might further be extended, since it probably includes many forms previously described as Rhipidomella Oehlert (1890) or Orthotichia Hall and Clarke (1892). Comparison.—Acosarina is assigned to the Ente- letacea on the basis of its punctate shell, ornament of tubular costellae, and juxtaposition of ventral median septum and dental plates. Among Permian genera, its fairly wide hinge and fully developed palintropes in both valves distinguish it effectively from Rhipido- mella, while its short dental plates and low, elongate ventral median septum differentiate it from Orthoti- chia. It is distinguished from Schizophoria King (1850) by the conservatism of internal structures in the ven- tral apex. Acosarina? sp. Plate 1, figures 7-9 Description.—Small, somewhat rostrate schizopho- riid, having relatively wide, straight hingeline, round- — ed outline, and hollow tubular costellae. Ventral in- terarea high, with narrow delthyrium. Ventral interior | having dorsally directed teeth, triangular in section, supported anteroventrally by short dental plates. Thin — median septum arising at apex, widening and becom- ing higher anteriorly, terminating anterior to ends of | dental plates. Dorsal valve unknown. Measurements (in mm).— Hinge Mid- Length Width Width Height LOCALITY 7 USNM 220981 11.0, 8.0), 10.3), 4.8. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 41 Occurrence.—The single partial ventral valve here tentatively assigned to Acosarina was recovered from locality 7. It was first recognized on the basis of its tubular costellae. Its more diagnostic interior details were later mechanically prepared. Diagnosis.—Schizophoriid ventral valve with fairly wide hinge, tubular costellae, short dental plates and long, low median septum. Types.—Figured and Measured Specimen: USNM 220981. Comparison.—(see generic discussion) The Palma- rito specimen is only provisionally assigned to the ge- nus because it is unknown whether the relative strength of dental plates and median septum in the ventral valve were altered during preparation, and be- cause only a single partial ventral valve was found. Discussion.—This specimen cannot unequivocally be assigned to Acosarina: indeed, on strictly morpho- logical grounds, it could be ascribed to Orthotichia. The known stratigraphic range of Orthotichia in West Texas extends only through the Bone Spring Forma- tion (Leonardian), while that of Acosarina in the same area extends through the Lower Guadalupian Word Formation. The majority of the fauna preserved at lo- cality 7 is most similar to uppermost Leonardian (Roadian) faunas in the West Texas area (see Table 3). In view of the great overall similarity between the Texas and Venezuelan Permian faunas, the differing ranges of the two genera there, and the present simi- larity of ventral valve internal arrangements of the Palmarito specimen to Acosarina, it is tentatively as- signed to that genus. Material.— Articu- Ven- Local- lated Dorsal tral Type of ity Valves Valves Valves Preservation 7 — — 1 calcite permineralization Order STROPHOMENIDA Opik, 1934 Suborder STROPHOMENIDINA Opik, 1934 Superfamily DERBYIACEA Stehli, 1954 Family DERBYIIDAE Stehli, 1954 Subfamily DERBYIINAE Stehli, 1954 Genus DERBYIA Waagen, 1884 Type Species.—Derbyia regularis Waagen, 1884, p. 594, pl. 53, figs. 1, 2, 4. Genolectotype by Hall and Clarke (1892). Diagnosis.—Derbyiinae having prominent single ventral median septum directly joined near sub-pseu- dodeltidial apex, without dental plates or spondylium. Occurrence.—Derbyia has been recovered from most of the world’s continents, and may be said to have a cosmopolitan distribution in the Early Permian, although its specific diversity is quite low in Boreal regions. The genus is known from Mississippian through Permian rocks, though it reaches its peak of specific diversity in the Late Pennsylvanian and Perm- ian. Comparison.—The character of the ventral median septum readily distinguishes Derbyia from other Permian genera of the Derbyiinae. In Licharewiella Sokolskaya (1960), the ventral median septum is con- tinuous anteriorly with a high transverse ridge; in Nothopindax Cooper and Grant (1974), the septum does not reach the valve floor. Outgrowths of the den- tal ridges onto the median septum of Derbyia may produce a shallow secondary ‘‘spondylium,’’ which should not be confused with the primary spondylium of the Orthotetidae. Discussion.—A complete and exhaustive discussion of the history and relationships of the genus Derbyia is presented elsewhere (Cooper and Grant, 1974, p. 289ff.), and it would be pointless to enlarge greatly upon it here. There are, however, certain asepcts of species assignment within the genus that must be dealt with. Presence or absence of secondary plications, which has been used even in supraspecific distinctions [e.g., Derbyia (Plicatoderbyia) Thomas (1937)], appears in itself to have no taxonomic significance even at the specific level (Cooper and Grant, 1974; Cooper, 1975), such features being present in several otherwise well- differentiated species of Derbyia. The outline and rel- ative dimensions (shape) are important taxonomic features at the species level, although many species exhibit considerable variation around a norm. Certain species [e.g., Derbyia laqueata Cooper and Grant (1974)] are defined as having rather wide ranges of variation in shape. Perhaps of more widespread usage in specific differentiation is primary surface ornament. Ornamentation in Derbyia consists chiefly of cos- tellae of various sizes and cross-sectional shapes. A misleading specific character is the density of costel- lation, which, as measured, is a gauge of both the size and the density of packing of the costellae. An addi- tional problem is that this feature is commonly mea- sured in terms of number of costellae in a five mm distance. Although the distance from the beak at which the measurement is taken is commonly stated 4? BULLETIN 313 as well, the number of costellae reported can vary considerably depending on the orientation of the line. Interior details are quite variable in many Orthote- tidina, yet may also be considered in specific diagno- ses. This practice is only reliable when a large suite of conspecific specimens is available for study. It fol- lows that reliable specific identifications within the ge- nus can only be made when suitably large collections are available, unless the taxon is externally quite dis- tinctive (e.g., Derbyia auriplexa, n. sp.). Derbyia auriplexa new species Plate 1, figures 30-36 Etymology of Name.—L. auri = ear; L. plexus = braided. Description.—Medium-sized for genus, thin-walled, unequally biconvex shell; dorsal valve more convex than ventral. Extremely auriculate, widest at hinge. Lateral margins constricted anterior to ears, diverging anteriorly to about midvalve; anterior commissure rectimarginate in dorsal or ventral aspect. Definite dorsal sulcus, arising just anterior to umbo, continuing to anterior margin, commonly interrupted by humps or dimples. Ornament of fine costellae (17-18 in five mm at 10 mm distance from dorsal umbo) increasing anteriorly by intercalation; costellae acute in section, anteriorly sinuous. Concentric growth lines generally absent, but strongly overlapping concentric growth la- mellae sporadically developed, producing step-like breaks in surface. Surface secondarily ‘‘braided,”’ with alternating humps and dimples. Costellae may arise, die out, split or coalesce on dimples or hollows, strengthening “‘braided”’ effect. Ventral valve low, planar to rounded triangular in lateral aspect, irregularly rounded in anterior aspect; greatest height about one-fourth shell length anterior of beak. Interarea apsacline, dorsoventrally striate, generally low, triangular, but commonly produced ventrally in beak area; pseudodeltidium long, narrow, triangular in outline, rounded to flat-topped in dorsal aspect, having smooth crest without median longitu- dinal groove. Dorsal valve convex in lateral aspect, convex to bilobate in anterior aspect. Umbo low, rounded, pro- duced slightly posterior to hingeline. Ventral interior having strong, anteriorly directed hinge teeth, triangular in cross-section, supported pos- teriorly by anteriorly divergent dental ridges. Low broad median swelling on underside of pseudodeltid- ium, dividing secondary spondylium into two parts. Long, thin, high median septum, scimitar-shaped in lateral aspect, having high point at about midlength, arising in delthyrial apex at junction of sub-pseudo- deltidial median ridge and dental ridges, extending an- teriorly about one-third to one-half valve length. Mus- cle scars large, ovate, smooth to striate, without callus rims. Interior otherwise smooth, but reflecting gross exterior ornament of dimples and humps. Dorsal interior having large cardinal process sup- ported by long, thin erismata that bend slightly laterad near dorsal ends. Low anteroventrally cuspate denti- fers crossing entire outer faces of erismata; thin bra- chiophores, square in lateral aspect, extending a few mm anteriorly from erismata, just dorsal of dentifers. Myophore bilobate, deeply cleft mesially, each lobe having posterior median slit, internally crenulate to denticulate distally. Chilidial plates low, disjunct, sep- arated by deep anteroposterior groove. Dorsal inter- area very low, having short swellings, which may function as fulcral plates, just laterad of chilidial plates. Low, distinct angular myophragm, flanked by ovate, striate to flabellate muscle scars, arising below cardinal process, continuing anteriorly about one- fourth shell length. Measurements (in mm).— Height or Hinge Mid- Thick- Surface Length Width Width ness Length Material LocaLity 13 USNM 220982 27.0. 41.6y. 31.4, 15.5 — (articulated valves) (holotype) USNM 220983 34.5 60.0), 41.0, 14.0 50.0 (dorsal valve) USNM 220984 34.6), 64.0), 37.6, 9.0, — (ventral valve) USNM 220985 38.8 63.0, 38.6 19.0 57.0 (dorsal valve) USNM 220985 45.0, 60.0), 47.0), 12.7 _ (ventral valve) PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 43 Occurrence.—D. auriplexa was recovered in good condition only from locality 13. Several partial ventral interareas and shell fragments with the characteristic bumpy ornament were recovered from locality 8. A single dorsal valve was recovered from locality 4. Lo- calities 8 and 13 are poorly defined stratigraphically but locality 4 is well-defined as within the Upper Lime- stone Member of the Palmarito Formation. Diagnosis.—Derbyia of moderate size with strongly braided, bumpy ornament and well-defined exagger- ated ears. Types.—Holotype: USNM 220982; Figured Speci- mens: USNM 220982, USNM 220983, USNM 220984; Measured Specimens: USNM 220982-220985. Comparison.—The only form closely related to D. auriplexa is D. cincinnata Cooper and Grant (1974), from the Cathedral Mountain and Road Canyon For- mations (Leonardian) of West Texas. D. cincinnata is in general not auriculate, and none of the specimens of that species in the National collections shows the uniformly extreme auriculation of the Venezuelan form. Internal features of the two species are quite similar, though they vary in a manner typical of the genus. They share the characteristic external orna- ment. Discussion.—A Leonardian-equivalent age for the portion of the Upper Palmarito Formation that con- tains D. auriplexa is not inconsistent with other lines of faunal evidence. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 4 1 1 — fine silicification 8 a — 1 fine silicification 13 1 6 4 fine silicification Derbyia cf. D. complicata Cooper and Grant Plate 1, figures 10-16 cf. Derbyia complicata Cooper and Grant, 1974, p. 296, pl. 81, figs. 4-38; pl. 88, figs. 1-6. Description.—Medium-sized, small- to medium- sized for genus, planoconvex to slightly biconvex, quadrate, commonly auriculate shell having mesially indented anterior margin and distinct dorsal sulcus. Hingeline straight, commonly widest part of shell. Surface ornament of alternating costellae and costae, commonly one costa to every four or five costellae. Costae best developed on visceral lobes of both valves, absent nearer hinge and within dorsal sulcus. Commonly seven costae on each side of dorsal sulcus and a like number on ventral valve, a single one mesial there. Costae and costellae crenulate, produced dis- tally, forming crenulate and irregularly serrate mar- gins. Costae of markedly uneven strength. Ventral valve planar to weakly convex, with slight to pronounced auriculation. Greatest height at or just anterior to beak. Interarea apsacline, triangular, flat to slightly concave, smooth to faintly dorsoventrally striate, having triangular delthyrium apically filled by distinct small pseudodeltidium. Pseudodeltidium smooth, lacking median groove or prominence. Dorsal valve moderately convex, broadly bilobate, greatest height at about midvalve. Ventral interior having strong, anteriorly directed hinge teeth, triangular in section, supported posterior- ly by distinct rounded dental ridges. Low, slender median septum arising anterior to delthyrial apex and extending to about one-fourth shell length. Muscle scars indistinct, smooth, flanking median septum. Sur- face smooth, but having deep radial furrows mirroring external costae, extending from distal margins of mus- cle attachment area to commissure. Anterolateral mar- gins somewhat serrate. Dorsal interior having small cardinal process sup- ported by anteriorly divergent erismata; erismata curving slightly posteriorly at distal ends. Dentifers low, subtle, produced anteroventrally as relatively large thin brachiophores. Myophore bilobate, cleft mesially, with short, internally crenulate slits on pos- terior faces of lobes, producing effective quadriloba- tion; posteriorly U-shaped in section. Chilidial plates comparatively large, triangular, overhanging low, nar- row dorsal interarea posteriorly, and bases of my- ophoral slits anteriorly. Short median keel lying be- tween chilidial plates in median groove of cardinal process. Surface generally smooth; many radial striae reflecting exterior costellae. Muscle scars indistinct, smooth, flanking low median rise that is an internal expression of exterior sulcus. 44 BULLETIN 313 Measurements (in mm).— Height or Hinge Mid- Thick- Length Width Width ness Material LocaLity 4 USNM 220986 12.8 19.0, 17.1 4.3 (dorsal valve) LocaLity 8 USNM 220987 15236 26.6), 18.9, 4.5. (ventral valve) USNM 220988 DIES 30.2, 30.3 10.7 (articulated valves) Occurrence.—D. complicata has been recovered only from the Cathedral Mountain and Road Canyon Formations in the West Texas region. In the Palmarito Formation D. cf. D. complicata is rare: a single artic- ulated specimen and several partial ventral valves were taken from locality 8, while a single partial dorsal valve was found at locality 4. The Leonardian age in- dicated by similarity of the two forms is not inconsis- tent with other biostratigraphic indicators for those two Palmarito localities. Diagnosis.—Small auriculate Derbyia with strong and unequal crenulate costellae and radial plications. Types.—Figured and Measured Specimens: USNM 220986-220988. Comparison.—D. cf. D. complicata may be recog- nized best by its auriculate hinge, weakly to strongly crenulate, uneven radial ornament, and well-devel- oped chilidial plates. It is clearly differentiable from other Palmarito forms of the genus: Derbyia auriplexa n. sp. has clearly non-crenulate radial ornament with superposed ‘“‘braiding’’ of humps and dimples; D. deltauriculata n. sp. has more regular, non-crenulate costellae; Derbyia cf. D. filosa Cooper and Grant (1974) is much larger. In the West Texas collections from which D. complicata was first described, it seems most closely related to D. laqueata Cooper and Grant (1974), D. texta Cooper and Grant (1974) and D. crenulata Girty (1909). The first is admitted by its authors to be ‘‘one of the most variable and least uni- fied of the Glass Mountains species of Derbyia’’ (Coo- per and Grant, 1974, p. 306). Some specimens in the Glass Mountains share the development of primary and secondary radial ornament, but none exhibit cren- ulation of that ornament. D. texta is commonly small- er and more compact that D. complicata, and its radial ornament tends to be somewhat coarser, and compli- cated by its more obvious concentric ornament. D. crenulata often bears two sizes of radial ornament, but the costae are all of roughly the same strength, in con- trast to their uneven expression in D. complicata. Discussion.—Vhe form of the pseudodeltidium of the Venezuelan form is questionable; it is only pre- served as a small triangular plate in the apex of one of the Palmarito specimens. It may well have originally been larger and more prominent. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 4 — 1 — fine silicification 8 1 — 3 fine silicification Derbyia deltauriculata new species Plate 1, figures 17-28 Etymology of Name.—Gr. delta = the Greek letter A = an equilateral triangle; L. auriculatus = auricu- late; eared. Description.—Small to medium sized for genus, thin-walled planoconvex to unequally biconvex shells having straight hingeline and broad dorsal sulcus. Commonly but not invariably widest at hinge; outline semicircular, quadrate, cardioid or irregular common- — ly modified by attachment. Shell commonly auriculate; ears small, equilaterally triangular. Surface finely cos- tellate (13 costellae in 5 mm at 20 mm from dorsal beak, increasing to 18-19 in 5 mm in zones of inter- calation), costellae commonly alternate in size, in- creasing anteriorly by intercalation in no systematic pattern. Costellae distinct, having straight sides and rounded crests, of various sizes along any growth line. Concentric ornament commonly limited to overlap- ping lamellae, best expressed on distal portions of valve. Ventral valve planar to slightly convex, having api- cal cicatrix of attachment. Greatest height at or just anterior to beak. Beak pointed, produced slightly pos- terior to hinge. Interarea flat to slightly concave, smooth, with surficially undifferentiated apparent peri-| deltidium and narrow rounded pseudodeltidium, latter bearing consistent distinct median groove; dorsopos-' terior surface of pseudodeltidium thus appearing bi-, lobate. Anterior margin of pseudodeltidium straight or’ PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 45 concave, with or without median salient correspond- ing to supra-pseudodeltidial median groove. Dorsal valve moderately to strongly convex. Ante- rior commissure straight or slightly indented; greatest height at about midvalve. Ventral interior having strong anteriorly directed hinge teeth, triangular in section. Dental ridges, nar- rower than teeth, running from distal edge of tooth base to delthyrial apex. Subpseudodeltidial median ridge present, commonly produced anteriorly as sa- lient, beyond anterodorsal pseudodeltidial margin. Median septum long, slender, scimitar-like, highest point commonly opposite anterior ends of hinge teeth. Muscle scars flabellate, anteriorly raised on slight pads, commonly with lobate rims, flanking median septum to its anterior termination. Remainder of in- terior surface smooth, except crenulate or radially grooved at anterolateral margins. Dorsal interior having relatively small cardinal pro- cess supported by short, fragile, laterad-curving eris- mata. Dentifers short, low. Chilidial plates disjunct, robust, reflexed over very low dorsal interarea. Lat- eral extensions of chilidial plates acting as fulcral plates. Cardinal process myophore bilobate, having short median cleft, each lobe bearing slit on posterior face. Myophore posteroventrally U-shaped in section, effectively quadrilobate. Low, broad, indistinct me- dian rise, separating indistinct smooth muscle scars, reflecting exterior sulcus. Anterior and lateral margins radially grooved to crenulate. Remainder of interior surface smooth to faintly striate, striae mirroring ex- ternal ornament. Measurements (in mm).— Hinge Mid- Length Width Width Height Material Loca.iry 10 USNM 220989 — 20.2 19.2 4.0 USNM 220990 14.1 28.6, 20.0 5.1 USNM 220991 USE2) E2510) | 2220) 6:4 USNM 220992 16.5 30.8, 27.2, 4.5 USNM 220993 20.9 35.3 27.1 4.8 (holotype) (ventral valve) (dorsal valve) (dorsal valve) (ventral valve) (ventral valve) Occurrence.—This species was recovered only from locality 10, where it is abundant. Diagnosis.—Medium-sized auriculate Derbyia with transverse outline, regular alternating straight costel- lae and distinct broad dorsal sulcus. Types.—Holotype: USNM 220993; Figured Speci- mens: USNM 220991, USNM 220993-220996; Mea- sured Specimens: USNM 220989-220993. Comparison.—Derbyia deltauriculata n. sp. is eas- ily distinguished from the other Palmarito species of that genus: from D. cf. D. complicata Cooper and Grant (1974) by its smooth costellae; from D. auri- plexa n. sp. by its evenly costellate surface; from D. cf. D. filosa Cooper and Grant (1974) by its small size. The common Bolivian Permian species, D. buchi (d’Orbigny, 1842) is easily distinguished by its more circular outline, coarser radial ornament, and the rar- ity of auriculation in that form. In all characters but auriculation, D. deltauriculata closely resembles the North American species D. crassa (Meek and Hay- den, 1858), especially some forms from the Permian (Wolfcampian) of Kansas. Specimens collected by G. A. Cooper in 1953 from the Florena Shale Member of the Beattie Limestone (USNM Acc. No. 199311) show striking similarities to the Palmarito species. They are not so auriculate, but are more so than the typical D. crassa. This form, not formally identified or described, may be intermediate between D. crassa and D. delt- auriculata, and is easily distinguished from the several subspecies of D. crassa erected by Dunbar and Con- dra (1932) by its auriculation. Discussion.—The type of D. crassa is of unknown stratigraphic position, but specimens referred by Dun- bar and Condra (1932) to this species are from units in the North American mid-continent which are from mid-Desmoinesian to mid-Virgilian in age. The speci- mens intermediate in auriculation between D. crassa and D. deltauriculata mentioned above are of mid- Wolfcampian age equivalent strata. It may be that au- riculation is a character which developed in the D. crassa stock during the Upper Paleozoic, but there are at present insufficient data to make more than this suggestion. Material .— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 10 4 26 30 fine silicification Derbyia cf. D. filosa Cooper and Grant Plate 2, figures 1-6 cf. Derbyia filosa Cooper and Grant, 1974, p. 300, pl. 82, figs. 1, 2, 11-36. Description.—Large, planoconvex to biconvex shells having straight hingeline; greatest height at or just anterior to umbo. Outline semi-circular. Greatest width at or just anterior to hingeline; slightly auriculate or not. Ornament of fine costellae of roughly uniform height, acute in section, separated by flat-bottomed troughs. Costellae arising at beak and increasing an- teriorly by intercalation, in four to five unsystemati- 46 BULLETIN 313 cally distributed generations; from 10 to 16 costellae, commonly 11 to 12, in a five mm distance. Surface may be secondarily dimpled, bumpy or braided, more commonly distally. Ventral valve beak asymmetrically produced and pursed or not, having apical cicatrix of attachment that may or may not obscure radial ornament. Interarea flat, triangular, apsacline, anteroposteriorly faintly striate. Convex pseudodeltidium, filling most of del- thyrium, exhibiting smoothly concave anterior margin and concentric growth lamellae. Dorsal valve commonly gently, rarely strongly con- vex, greatest height at or posterior to midvalve. Umbo produced slightly beyond hingeline. Ventral interior having strong hinge teeth, triangular in section, directed anteriorly, buttressed interiorly by long dental ridges; ridges diverging anteriorly at about 30° on inner face of interarea. Vault of pseudodeltid- ium having low, rounded, median longitudinal ridge, merging posteriorly with larger base of median sep- tum. Rounded, excavate bilateral fossae (=secondary spondylium of Cooper and Grant, 1974) formed at junction of sub-pseudodeltidial median ridge, dental ridges and median septum. Median septum high, thin, extending anteriorly only to anterior margin of diduc- tor muscle scars. Muscle scars smooth, indistinct; in- terior surface otherwise smooth. Dorsal interior having large cardinal process and long thin erismata. Latter bearing low dentifers that do not extend dorsad to hinge. Hinge sockets well- defined by dentifers, erismata, hingeline and low broad swelling on lateral slope of erismata anterior to den- tifers. Lateral lobes of cardinal process joined dorsad to broad disjunct chilidial plates. Plates, separated by deep mesial groove, anterodorsally overhanging re- duced dorsal interarea as thin reflexed lips. Cardinal process myophore bilobate ventrally, lateral lobes deeply excavate anteroposteriorly on dorsal faces; lobes U-shaped in posterior aspect. Inner faces of myophoral slits crenulate to denticulate, with definite lipped rims. Large muscle field, apparently smooth or striate and contained by erismata; may be divided by low, rounded median ridge, in some specimens ex- tending up onto cardinal process shaft. Measurements (in mm).— Hinge Length Width Height Material Loca.iry 11 USNM 220997 — 77.0; 15.2 (ventral valve) USNM 220998 60.9 85.0), —_— (ventral valve) Occurrence.—In the West Texas region where it was first described, D. filosa has been recovered from the Road Canyon, Word and Cherry Canyon Forma- tions, of Late Leonardian and Early Guadalupian age. In the Palmarito Formation it is known only from lo- cality 11. A Late Leonardian to Early Guadalupian age for the beds at that locality is not inconsistent with other biostratigraphic indicators. Diagnosis.—Large Derbyia having weak, relatively widely spaced costellae and a strong, reflexed bilobate chilidium. Types.—Figured Specimens: USNM 220998221001; Measured Specimens: USNM 220997-220998. Comparison.—D. filosa is characterized by its flat- tish ventral valve, strong, relatively uncrowded cos- tellae, auriculate hinge and short plates which join the median septum to the dental ridges. While the Pal- marito form shares most of these characters, the expression of the ears cannot be ascertained in the extremely limited number of complete specimens available, and the costellae seem uniformly weaker than those of West Texas D. filosa. The Venezuelan form may be distinguished from most other species of Derbyia by its large mature size and its relatively widely spaced costellae; its prominent bilobate re- flexed chilidium distinguishes it from otherwise similar forms like D. informis Cooper and Grant (1974), D. nasuta Girty (1909) and D. pannucia Cooper and Grant (1974). Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 11 1 8 4 medium-grained silicification Derbyia sp. Plate 1, figure 29 Discussion.—Specimens of both juvenile and adult Derbyia exhibiting the diagnostic single ventral me- dian septum, but lacking either sufficiently good pres- ervation or adequate numbers of specimens for spe- — cific identification were recovered from localities 3, 4, — 6 (block C) and 13. Mature specimens (beak area of © a single ventral valve) were found only at locality 4. _ All other material was complete or partial valves, mostly ventral. Types.—Figured Specimen: USNM 221002. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 47 Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 3 — 2 — fine silicification 4 — 1 1 fine silicification 6 —_ — 1 fine silicification (block C) 13 _ 3 4 fine silicification Family MEEKELLIDAE Stehli, 1954 Genus MEEKELLA White and St. John, 1867 Type Species.—Plicatula striato-costata Cox, in Owen, 1857, p. 568, pl. 8, fig. 7. Diagnosis.—Meekellidae in which the dental plates meet the floor of the ventral valve without joining. Occurrence.—Meekella has been recovered from all the Americas, Europe, Asia and parts of southeast Asia. It is known from uppermost Desmoinesian to Upper Guadalupian equivalent rocks, although its most cosmopolitan distribution was reached in the Lower Permian, when its range extended to the edges of the Boreal realm (Stehli and Grant, 1970). It has not been recovered from Africa or Australia, and it is ex- pected that future studies will maintain its largely Tethyan affinities. Comparison.—Meekella is the only genus of the Meekellidae to be recovered from the Palmarito. It may easily be distinguished from most other meekellid genera by the internal details of the ventral valve, and from Niviconia Cooper and Grant (1974) by the rela- tive conservatism of its articulatory and visceral sup- portive apparatus. Discussion.—Meekella is represented in the Pal- marito by a single, variable species that is identified on the basis of several very small suites of specimens. Cooper and Grant (1974, p. 352) have succinctly sum- marized one great difficulty in identification of species of Meekella: ‘‘Species of Meekella ... are highly variable.’ Interior details, while important for generic differentiation, are notoriously unreliable in specific taxonomy, since both cardinal process and dental ap- paratus change so remarkably during the course of ontogeny of a single individual. Exterior details used extensively in specific identifications may be masked Or missing in some specimens, and indeed may appear only in certain growth stages of the animal. Taxonom- ically significant parameters of many species of Meek- _ ella vary over wide ranges, the norm of which is dif- ficult to determine without the aid of a large number of specimens. The poor preservation of small numbers of specimens of the Venezuelan forms thus allow spe- cific identification in only a single case. Meekella skenoides Girty Plate 2, figures 7-16 Meekella skenoides Girty, 1909, p. 206, pl. 30, figs. 8, 9; R. E. King, 1931, p. 56, pl. 7, figs. 6-8; Newell, Rigby er al., 1953, pl. 21, fig. 1; Cooper and Grant, 1974, p. 370, pl. 99, figs. 40-41; pl. 101, figs. 9-13; pl. 104, figs. 1-10; pl. 108, figs. 6-10; pl. 115, figs. 1- 32; pl. 116, figs. 1-8. Meekella difficilis Girty, 1909, p. 206, pl. 30, fig. 10 (non R. E. King, 1931, p. 53, pl. 4, figs. 16, 17; pl. 5, fig. 1). Description.—Medium to large-sized, small to me- dium-sized for genus, moderately to strongly bicon- vex, inequivalved, having high conical ventral and bowl-like dorsal valves. Outline transversely oval to subcircular; commonly widest at about midlength. Hingeline short, straight; commissure rectimarginate, serrate. Surface ornament of fine costellae (commonly five in a one mm distance); costellae increasing ante- riorly, commonly by intercalation, rarely by splitting. Oblique-sided angular plicae, superposed on costellae, arising about eight mm from dorsal or ventral um- bones, increasing anteriorly in width and height, not number; very rarely bifurcating, six to eight on each flank, from 13 to 16 per valve. Plicae strongest at an- terior margin, becoming obsolete posteriorly and lat- erally. Ventral valve shallow to deep, most commonly deep, up to two-thirds as high as wide, cone-like, hav- ing apical to subapical cicatrix of attachment; greatest height commonly just anterior to beak. Interarea small, high, smooth, triangular to curved triangular, commonly symmetric in small, apparent juvenile spec- imens, commonly asymmetric in larger, apparently more mature individuals. Triangular delthyrium com- pletely filled by pseudodeltidium that is laterally bounded by striae at delthyrial margin and has a dis- tinct rounded monticulus with mesial groove. Anterior margin of pseudodeltidium straight, concave if broken. Dorsal valve swollen, commonly one-half as high as wide; greatest height at one-third to one-half valve length from beak. Slightly auriculate, tiny triangular ears extending as thin plates to lateral extremities of ventral interarea. Ventral interior having distinct median sub-pseu- dodeltidial groove and strong, anteriorly directed hinge teeth, supported by dental ridges. Dental ridges strong, supported posteriorly by thin dental plates: plates arising, keel-like, near anterior ends of teeth. Dental plates straight, converging but not meeting be- 48 BULLETIN 313 fore contacting floor of valve; not modified, except anteroposteriorly striate toward anteroventral extrem- ities in larger individuals. Surface smooth, anteriorly plicate, reflecting exterior ornament. Muscle attach- ment field smooth, indistinct, even in large specimens. Dorsal interior having long cardinal process that arises normal to plane of valve. Bilobate myophore recurved sharply posteriorly; lobes slit posterodorsal- ly; slits arising one-half way up vertical shaft, con- tinuing to distal end of myophore. Myophore mesially cleft, lobes separate but closely appressed about one- half distance up myophore. Shaft supported dorsally by very thin erismata that diverge anteriorly at about 50° in plane defined by their anterior edges. Posterior face of myophore grooved dorsad to cleft; mesially cleft keel present in some specimens. Dentifers pres- ent as comparatively large alate extensions on sides of erismata, extending ventroposteriorly as slender, pointed brachiophores. Proximal ends of dentifers cleft, having fulcral plate fused to palintrope. Subcar- dinal cavity deep, commonly smooth, having low, rounded but distinct median ridge arising abruptly just anterior to umbo and terminating anterior to distal ends of erismata. Remainder of surface broadly pli- cate, mirroring exterior ornament. Measurements (in mm).— Height Hinge Maximum or Thick- Length Width Width ness Material Loca.irty 3 USNM 221003 7.4 6.5 10.4 6.5 (articulated valves) USNM 221004 11.8, 6.5 12.6 Wile (articulated valves) USNM 221005 15.4 9.1 13.1 16.5 (articulated valves) LocaLity 4 USNM 221006 26.3, 27.6 33.5. Tee) (dorsal valve) USNM 221007 30.3, 20.9), 32.4, 10.7 (dorsal valve) Occurrence.—Meekella skenoides is known in the West Texas area from the Road Canyon, Cherry Can- yon, Word, Bell Canyon and Capitan Formations of Late Leonardian and Guadalupian age. In the Palma- rito Formation it is recognized at localities 3, 4, 7, 8 and 11, while a single partial dorsal valve was re- covered in float in the Quebrada de Portachuelo (Field No. PRH-71-VE-23). Specimens which may be refer- able to the species were described as Meekella sp. (Stehli and Grant, 1970 [p. 27, pl. 7, figs. 37—40]) from the Chochal Limestone (Leonardian) of Guatemala. The Late Leonardian or Guadalupian age of the West Texas specimens does not contradict the ages of the above Palmarito assemblages as based on other bio- stratigraphic indicators. Diagnosis.—Medium-sized to large Meekella with strong angular plications averaging twelve in number. Types.—Figured Specimens: USNM 221003-—221005, USNM 221007—221011; Measured Specimens: USNM 221003—221007. Comparison.—Meekella skenoides is characterized by its moderate size (rarely more than 50 mm wide), regular sharp plications arising near the beak, small ears, separate dental plates and proportionately high interarea. Of the species of Meekella which reach a comparable size, only a few are similar. M. occiden- talis (Newberry, 1861) is distinguished by its larger size, more prominent auriculation, and more uniform- © ly divergent costellae. M. prionota Cooper and Grant (1974) possesses a prominent dorsal sulcus, a feature that is rarely observed in M. skenoides, but is never so strongly expressed. M. skenoides attains a smaller maximum size than does M. magnifica Cooper and Grant (1974). Smaller individuals of M. skenoides might be mistaken for M. attenuata Girty (1909), but typical specimens of that species are less deep and have fewer costae. The auriculate cardinal extremities of M. calathica Cooper and Grant (1974) immediately distinguish it from M. skenoides. | Discussion.—The small maximum size attained by individuals recovered from Palmarito locality 3 may — in part be the result of current sorting. The species is _ here commonly found firmly attached to sponges, and | the largest specimens are commonly quite fragmented. | Breakage of larger specimens of this fragile thin-- shelled form would seem inevitable in a strong current! regime. Material.— | i PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 49 Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation Field No. — 1 — fine silicification PRH-71-VE-23 3 9 24 24 fine silicification 4 1 5 — fine silicification 7 1 — — calcite permineralization 8 — 2 3 fine silicification 1 11 — — coarse silicification Superfamily CHONETACEA Muir-Wood, 1962 Family RUGOSOCHONETIDAE Muir-Wood, 1962 Diagnosis.—Small to large Chonetacea; shell rarely thickened; externally smooth, capillate, costellate or lamellose, rarely rugose. Median fold and sulcus var- iably developed; dorsal interarea may be reflexed. Spine row at variable angles to hinge, spinules usually developed. Median, lateral and commonly accessory septa developed in dorsal valve. Alveolus well-devel- oped, deep; brachial ridges prominent. Adductor scars smooth or rarely dendritic; no accessory adductors. Discussion.—The original diagnosis of the Rugoso- chonetinae, of the family Chonetidae Muir-Wood (1962), was far less comprehensive than the above. Cooper and Grant (1974) elevated the taxon to family rank, citing as justification the marked differences in internal structure between the rugosochonetids and earlier Paleozoic chonetaceans, especially in the na- ture of the cardinal process. That family diagnosis is here expanded to include forms like Stauromata new genus, which, except for certain internal details, are well within the range of variation of the Rugosocho- netidae as previously recognized. Subfamily RUGOSOCHONETINAE Muir-Wood, 1962 Diagnosis.—Small to moderately large, transverse, smooth to costellate, usually having ventral sulcus; spine row oblique; chilidium and pseudodeltidium usually present. Ventral interior having short posterior median septum and low, commonly anterospinose median ridge; surface strongly papillose. Dorsal inte- rior having deep alveolus, usually well-developed; an- deridia commonly protuberant; median septum long; adductors smooth; lateral regions usually strongly en- dospinose. Discussion.—The subfamily includes the Late Pa- leozoic genera Rugosochonetes Sokolskaya (1950), Dyoros Stehli (1954), Eolissochonetes Hoare (1960), Leurosina Cooper and Grant (1975), Lissochonetes Dunbar and Condra (1932), Mesolobus Dunbar and Condra (1932), Neochonetes Muir-Wood (1962), Quadrochonetes Stehli (1954), Stauromata new genus and Sulcataria Cooper and Grant (1969). Dyoros and Stauromata are recognized in the present collections. Genus DYOROS Stehli, 1954 Type Species.—Chonetes consanguineus Girty, 1929, p. 409, figs. 8, 9. Diagnosis.—Wide-hinged smooth Chonetacea with sulcus varying from deep to barely visible, the pedicle valve and visceral region usually strongly fringed by spines on the anterolateral side. Occurrence.—Dyoros to date has been recognized only in the western United States, where it occurs in units that range in age from Leonardian to Guadalu- pian, although the type species, D. consanguineus (Girty, 1929) has been reported from the Wolfcampian Skinner Ranch Formation. A single dorsal valve (USNM 163553) from the Chochal Limestone (Leo- nardian) of Guatemala, described as ‘‘Neochonetes sp.’’ (Stehli and Grant, 1970), is more properly placed in Dyoros, on the basis of its distinct median sulcus and internal anterior spinose fringe in the dorsal valve. Comparison.—Dyoros differs from Leurosina Coo- per and Grant (1975) and Neochonetes Muir-Wood (1962) in its possession of a definite median deflection, and from Lissochonetes Dunbar and Condra (1932) in the stronger expression of its internal details, partic- ularly endospines. It differs from Eolissochonetes Hoare (1960), Mesolobus Dunbar and Condra (1932), Quadrochonetes Stehli (1954), Rugosochonetes So- kolskaya (1950) and Sulcataria Cooper and Grant (1969) in its distinct anterior endospinose fringes in the dorsal valve. Stauromata new genus, though quite similar to Dyoros, is distinguished by its unique an- teroventral endospinose palisades. Discussion.—Cooper and Grant (1975) have recog- nized three groups of species of Dyoros in the West Texas area, to which they have assigned the rank of subgenera: Dyoros (Dyoros), distinguished by its strong ears and deep sulcus; Dyoros (Lissosia), dis- tinguished by its strong ears and reduced sulcus; Dy- oros (Tetragonetes), distinguished by its reduced ears, nearly vertical sides and strong sulcus. Although the form of Dyoros here described is closest to D. (Tet- ragonetes), it is felt that an unequivocal assignment of the Venezuelan forms to a particular subgenus of Dy- oros is unwarranted. Dyoros acanthopelix new species Plate 2, figures 17-26 Etymology of Name.—Gr. akantha = pelyx = bowl. Description.—Small, rectangular to transverse au- riculate shells having straight hingeline and small tri- angular ears. Commissure rounded rectangular to semicircular in outline; not straight anteriorly, com- monly having very broad dorsal fold and ventral sul- cus. Well-preserved surfaces smooth, some poorly preserved, slightly decorticated individuals having ra- dially disposed taleolar traces. Concentric growth lines not conspicuous in early growth stages; overlap- ping lamellae often present in later shell accretions. Ventral valve convex, having greatest height near midvalve. Three to five posterolaterally directed hinge spines, oriented at about 30° to hinge on either side of low beak. Interarea low, apsacline, slightly concave, faintly dorsoventrally striate. Narrow, crescentic, hood-like pseudodeltidium filling apex of small trian- gular delthyrium. Dorsal valve concave to planar. Interarea very low, commonly one-half height of ventral interarea, ana- cline to hypercline. Chilidial plates disjunct, covering portions of exterior sides and base of myophore. Ventral interior having short ventrolaterally direct- ed hinge teeth, unsupported by dental plates. Rounded to subcircular boss-like thickening of posteriormost median septum bearing two or more vertical grooves corresponding in position to lobes of myophore. Me- dian septum narrow, bladelike anteriorly, thicker and higher near midvalve, there bearing stout endospines or tubercles on crest. Septum commonly ending short of anterior margin. Diductor scars oval, longitudinally striate or smooth, anterolaterally bounded by large endospines; spines apparently set on low rounded ridge or platform, reflecting form of brachial ridges of opposite valve. Inner surfaces of anterior and lateral margins and ears covered by numerous small pustules, in radial rows nearer margins. Dorsal interior having short, stout cardinal process, supported by thin outer socket ridges, broad inner socket ridges and broad anderidia. Anterior margins of outer socket ridges diverging slightly from hinge- line. Inner socket ridges straight, widening anterolat- erally. Cardinal process shaft short, thick; myophore bilobate, effectively quadrilobate, each lobe mesially thorn; Gr. BULLETIN 313 striate on posteroventral surface. Median septum thin, arising from junction of anderidia just anterior to deep submyophoral alveolus, continuing anteriorly just be- yond midvalve, there thickened and commonly bear- ing small tubercles on crest. Broad anderidia arising from beneath inner socket ridges, extending antero- laterally to near midvalve, terminating in cluster of distally oriented endospines. Smaller endospines cov- ering area with low rounded brachial ridges that ex- tend anteriorly and laterally to valve margins. Brachial ridges indistinct, some marked by narrow zone of en- dospines arising at deep hollow between inner socket ridge and anderidium, spines increasing in size as ridges curve around just anterolateral of anterior end of median septum. Measurements (in mm).— Hinge Mid- Thick- Length Width Width ness LocaLity 2 USNM 221012 3.5 Salty 4.4 1.0 USNM 221013 5.0 Te] 6.9 1.3 USNM 221014 5.0 8.2 7.6 1.1 USNM 221015 Sal 6.5 6.4, 1.6 USNM 221016 a2 7.4, 6.6 1.4 USNM 221017 5.8 7.8, 8.0, 233 USNM 221018 5:9 10.8, 8.4 1.2 USNM 221019 6.0 8.8, 8.0 1.6 USNM 221020 6.2 8.8 8.5 1.6 USNM 221021 6.3, 10.4, 9.9 E7/ USNM 221022 6.9 10.2 9.3 Ne7/ USNM 221023 Ue? 10.5 93 2.1 USNM 221024 Hell 10.8), 10.0 2:9) USNM 221025 7.8 11.0), 10.9 1.9 (holotype) USNM 221026 OF 11.7 12.5 3.3 USNM 221027 9.1, 12.1, 11.4, 2.9 USNM 221028 9.2 11.3 11.2 3.0 USNM 221029 9.4 14.7), 13.1 3.3 USNM 221030 9.5 14.3 12.9 2.3 USNM 221031 9.5 13.6, 14.6 3.2 USNM 221032 10.5 17.8 IS) 7 3.7 Occurrence.—Dyoros acanthopelix appears in the present collections only at locality 2. Diagnosis. —Medium-sized, thin, quadrate Dyoros having strongly endospinose ventral interior and strongly tuberculate anteriorly elevated ventral medi- an septum. Types.—Holotype: USNM 221025; Figured Speci- mens: USNM 221012, USNM 221019, USNM 221025, USNM 221026, USNM 221031, USNM 221033- 221035; Measured Specimens: USNM 221011—221032. Comparison.—Dyoros acanthopelix is easily distin- guished from the other Palmarito chonetaceans: from Stauromata esoterica n. gen. and sp. on the basis of PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 51 its smaller size, less pronounced fold and sulcus de- velopment, and the striking interior details of the latter form, and from Chonetinetes cf. C. varians Cooper and Grant (1975) on the basis of the squarer outline, more globose form and more conservative ventral in- terior exhibited by that form. D. acanthopelix may be distinguished from many of the other species of the genus on the basis of its au- riculate, but not acuminate or alate outline. These in- clude D. (Dyoros) angulatus Cooper and Grant (1975), D. (Dyoros) attenuatus Cooper and Grant (1975), D. (Dyoros) endospinus Cooper and Grant (1975). D. (Dyoros) extensiformis Cooper and Grant (1975), D. (Dyoros) extensus Cooper and Grant (1975), D. (Dyoros) intrepidus Cooper and Grant (1975), D. (Dyoros) hillanus (Girty, 1909), D. (Dy- oros) robustus Cooper and Grant (1975), D. (Dyoros) transversus Cooper and Grant (1975) and D. (Lisso- sia) vagabundus Cooper and Grant (1975). It may be differentiated from all species of Dyoros except D. (Dyoros) magnus Stehli (1954), D. (Dyoros) planiex- tensus Cooper and Grant (1975), D. (Dyoros) tenuis Cooper and Grant (1975), D. (Lissosia) parvus Coo- per and Grant (1975) and the species of D. (Tetrago- netes) on the basis of its quadrate form, and from D. (Dyoros) magnus and D. (Tetragonetes) giganteus Cooper and Grant (1975) on the basis of its smaller size. It may be distinguished from D. (Dyoros) con- sanguineus (Girty, 1929), D. (Dyoros) convexus Coo- per and Grant (1975), D. (Dyoros) vulgaris Cooper and Grant (1975), D. (Lissosia) concavus Cooper and Grant (1975), D. (Tetragonetes) auriculatus Cooper and Grant (1975), D. (Tetragonetes) quadrangulatus Cooper and Grant (1975), D. (Tetragonetes) solidus _ Cooper and Grant (1975), D. (Dyoros) subliratus (Gir- ty, 1909) and D. (Tetragonetes) subquadratus Cooper and Grant (1975), on the basis of its profile: thinner | than those deeper, more globose forms. It is distin- | guished from all other species of Dyoros in the ex- _ traordinary development of ventral endospines. These are arranged in dense patches anterior to the adductor muscle field and along the crest of the enlarged, an- teriorly elevated median septum. D. (Dyoros) endo- _spinus also has large ventral endospines, but in that _ form the spines are located more posteriorly, and are | much longer and thinner than those in D. acantho- pelix. D. (Dyoros) transversus also exhibits exagger- _ ated endospinose development in its ventral valve, but _ the spines in that form are located along the boundary between the visceral cavity and the ears, instead of | anterior to the muscle fields, as in D. acanthopelix. D. (Tetragonetes) strigosus Cooper and Grant (1975) exhibits random scatterings of endospines anterior to the ventral adductor field, but no distinct elevated or tuberculated ventral median septum. Of the three subgenera of Dyoros proposed by Coo- per and Grant, D. acanthopelix is probably most closely allied to species of D. (Tetragonetes). Two diagnostic characters of that group in the West Texas region are the lack of strong endospines and the de- velopment of a strong sulcus in the ventral valve. Since the first of these criteria clearly is not satisfied and since the second is difficult to ascertain, due to the dorsoventral crushing common in individuals from locality 2, I have placed the new form within the genus Dyoros (sensu lato). Discussion.—Specimens of D. acanthopelix in sev- eral ways foreshadow individuals of Stauromata eso- terica n. gen. and sp. The clusters of endospines on the ventral valve floor anterior to the adductor attach- ment scars in D. acanthopelix could, through the course of ontogeny, develop into the comparatively massive anteroventral endospinose palisades seen in S. esoterica. Since, however, there is no direct evi- dence to indicate the comparative immaturity of any of the forms herein assigned to D. acanthopelix, such suggestions cannot be formalized to the extent of in- cluding one form in the synonymy of the other. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 2 85 34 35 calcite permineralization (fluoritized in preparation) Genus STAUROMATA new genus Etymology of Name.—Gr. stauromatos = pali- sades. Description.—Slightly to highly concavo-convex transverse shell having straight hingeline, strong ven- tral sulcus and broad dorsal fold. Outline symmetri- cally trapezoidal, sides tapering anteriorly. Commis- sure W-shaped in ventral aspect, straight in anterior aspect. Beak low; hinge spines at low angles to hinge. Shell smooth to faintly capillate; finely pitted if de- corticated. Ventral valve convex, greatest height at or just pos- terior to midvalve. Interarea low, wide, apsacline. Hood-like crescentic pseudodeltidium filling small tri- angular delthyrium. Dorsal valve moderately concave, greatest depth near mid-valve. Lateral margins reflexed dorsally, 52 BULLETIN 313 sloping to planar ears. Interarea anacline, reflexed; tri- angular secondary interarea present. Chilidial plates conjunct, smooth. Small, spinelike chilidial boss pro- truding dorsally beyond interarea. Ventral interior having small anteriorly directed hinge teeth, triangular in section. Delthyrial apex filled by boss-like secondary shell material, median boss merging anteriorly into median septum. Septum con- tinuing anteriorly, merging into median ridge. Smooth posterior adductors, dendritic anterior adductors. Deeply excavate apparent diductor attachment scars, fringed mesially and posteriorly by high anterodorsally directed palisades of coalesced endospines. Dorsal interior having inner and outer socket ridges and strong anderidia. Anderidia anteroventrally free, terminally endospinose. Alveolus deep. Adductors smooth. Thin median septum arising anterior to alveo- lus, broadening anteriorly. Apparent marginal rim of coalesced endospines around visceral disk. Type Species.—Stauromata esoterica new species. Diagnosis.—Rugosochonetinae having deeply ex- cavate apparent ventral diductor attachment scars, fringed by palisades of coalesced endospines. Occurrence.—Stauromata new genus is known only from the Palmarito Formation, at localities 1, 4, 7 and 8. Comparison.—Stauromata is externally homeo- morphous with many species of the genera Choneti- nella Ramsbottom (1952) and Dyoros Stehli (1954), but its exaggerated internal characters serve to clearly dif- ferentiate it from either of those genera. Of the two, it is probably more closely related to Dyoros, but the striking palisade-like development of coalesced en- dospines is thought sufficient to warrant a new generic designation. Discussion.—Specimens of Stauromata from local- ities | and 7 were first erroneously assigned to Cho- netinella, on the basis of external characters, although this assignment was not formalized through publica- tion. Later preparation revealed the internal features that allowed recognition of the greater similarity to but clearcut difference from, the genus Dyoros. Stauromata esoterica new species Plate 2, figures 33-37; Plate 3, figures 1-25; Plate 4, figures 1, 2 Etymology of Name.—Gr. esoterikos = inside. Description.—Small to medium-sized, average-sized for genus, slightly to highly concavo-convex, trans- verse shell having straight hingeline, strong ventral sul- cus and dorsal fold. Outline symmetrically trapezoi- dal, sides tapering anteriorly. Commissure W-shaped in ventral aspect, straight in anterior aspect. Beak low, flanked by five to seven spines that lie at low angles to hingeline. Shell faintly capillate, finely pitted if de- corticated. Pits rounded to radially elongate, randomly scattered, in radial rows, or in radial and concentric rows. Ventral valve convex, greatest height at or just pos- terior to midvalve. Visceral lobes high, rounded, di- verging anteriorly at about 30°, intervening sulcus aris- ing just anterior to beak. Interarea low, wide, apsacline. Hood-like crescentic pseudodeltidium fill- ing small triangular delthyrium. Dorsal valve moderately concave, greatest depth near midvalve. Sharp median fold arising one-fourth shell length anterior to beak. Lateral margins reflexed dorsally, sloping to planar ears. Interarea anacline, reflexed; triangular secondary interarea present. Chi- lidial plates conjunct, smooth. Small spinelike chilidial boss protruding dorsally beyond interarea. Ventral interior having small anteriorly directed hinge teeth, triangular in section; entire beak and in- terarea supported by low rounded swelling originating © in delthyrial cavity and running below interarea to-— ward lateral extremities. Delthyrial apex filled by boss- like secondary shell material; median boss merging | anteriorly into broad median septum. Septum continu- ing to anterior margin of adductors, at about one-— fourth shell length, there becoming thin, blade-like median ridge, extending almost to anterior margin. Posterior adductors small, ovate, smooth, covering lateral surfaces of posteriormost median septum on slightly thickened shell plate, lapping slightly onto valve floor. Anterior adductors ovate to triangular, dendritic to cuspate, on slightly raised portions of valve floor, lapping onto median septum. Apparent diductors deeply excavate, striate; fringed by palisade of coalesced endospines. Remainder of surface finely papillose, granulose to endospinose; endospines stout- er anterior to end of median septum, on radial ridges’ nearer lateral margins. Dorsal interior having narrow outer and broad inner socket ridges; long, strong, anteroventrally free and endospinose anderidia. Cardinal process myophore quadrilobate. Alveolus deep, steep-sided posteriorly, gradually sloping anteriorly. Dorsal adductors small, smooth. Thin median septum arising a short distance anterior to alveolus, broadening anteriorly, terminat- ing short of anterior margin in cluster of endospines.. Apparent marginal rims of coalesced endospines around visceral disk, gradually sloping mesially, abrupt distally. | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER Measurements (in mm).— Hinge Mid- — Thick- Length Width Width ness LocaLity 4 USNM 221036 11.0 21.0 13.0 4.5 (ventral valve) Loca.ity 1 USNM 221037 11.6 DHES® 17/59/ 4.7. LOcALITy 7 USNM 221038 11.3 20.0 17.6 4.8. USNM 221039 11.4 20.8 16.4 4.8. USNM 221040 11.8 20.0 16.5 5.0,. (holotype) USNM 221041 12.6 19.0 16.7, 5.6 USNM 221042 14.1 20.5 17.6 7.4, Occurrence.—as for genus. Diagnosis.—as for genus. Types.—Holotype: USNM 221040; Figured Speci- mens: USNM 221036, USNM 221039, USNM 221040, USNM 221043-221045; Measured Specimens: USNM 221036-221042. Comparison.—Stauromata esoterica is the only known species of the genus. It may, however, be closely related to species of the genus Dyoros, espe- cially D. acanthopelix n. sp., which resembles an hy- pothetical immature form of S. esoterica. No speci- mens of §. esoterica were recovered in which the endospinose development was not fully expressed. D. acanthopelix, with its ventral valve lined by endo- spines, would make a suitable precursor to S. esoter- ica. Since they do not occur together, however, no suggestion of more than chance resemblance can be made at this time. Discussion.—Very few of the present specimens of _S. esoterica were silicified. Ordinary mechanical prep- aration with a needle failed to delineate sufficiently the internal features of the new form. In order to clarify the relationships of internal structures in both valves, twenty serial acetate peels of a single set of articulated valves (USNM 221045) were made. Instead of being oriented in the usual fashion, normal to plane of com- missure, the sections were made parallel to the com- missural plane. This was done so that finished sche- ‘matic reconstructions could simulate conventional interior views of the valves. An attempt, largely suc- cessful, was made to keep a 0.15 mm spacing between successive sections. The peels were projected, at 10x magnification, onto 1.5 mm thick sheets of Plexiglas, using a photographic enlarger, and pertinent details inked thereon. Using reference marks to ensure their | | tn Ww proper juxtaposition, a stack of sections were bolted together and photographed in stereo, to give an illu- sion of depth to the reconstructions. The peels, mag- nified x2, and the schematic reconstructions of both valve interiors, magnified x4, are presented as Plate 3. Although not all interior details are clear, one may distinguish the endospinose anterolateral fringes and median septum of the dorsal valve, and the palisade development of the ventral valve. In addition, it is readily apparent that the laterally expanded distally endospinose anderidia of the dorsal interior extend posterior to the ventral palisades. Whether this jux- taposition is an artifact of taphonomic crushing, or represents an operational life relationship is unknown. It seems likely that the combination of dorsal and ven- tral endospines formed an impressive barrier across the posterior portion of the valve. The function of this barrier might be speculated upon a great length. One obvious possibility is that of a structure to control and direct incurrent and excurrent flow. Another possible function might be body wall and (or) lophophore sup- port. Arguments in favor of one or another of these possibilities should probably wait until the study of additional sections clarifies the relationships of the various structures observed. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 4 = 5 calcite permineralization 4 — — 1 medium silicification 1 14 — 2 calcite permineralization 8 — 2 medium silicification Subfamily CHONETINELLINAE Muir-Wood, 1962 Genus CHONETINETES Cooper and Grant, 1969 Type Species.—Chonetinetes reversus Cooper and Grant, 1969, p. 4, pl. 3, figs. 1-7. Diagnosis.—Small, wide-hinged Chonetacea having the fold and sulcus best developed in the umbonal re- gion and with subconical mounds of taleolae on each side of the visceral region toward the anterolateral margins. Occurrence.—Species assigned to the genus are known, to date, from the Road Canyon and Bell Can- yon Formations (uppermost Leonardian and Upper Guadalupian) of the West Texas area. Comparison.—Chonetinetes is easily distinguished from Chonetina Krotov (1888), by its smooth exterior and single median septum. It differs from Chonetinella Ramsbottom (1952) in its smaller size and its incom- 54 BULLETIN 313 plete ventral sulcus, which becomes weaker anterior- ly. Discussion.—This report constitutes the first known occurrence of the genus in South America. Chonetinetes cf. C. varians Cooper and Grant Plate 2, figures 27-32 cf. Chonetinetes varians Cooper and Grant, 1975, p. 1285, pl. 477, figs. 54-S8. Description.—Small, medium-sized for genus, con- cavo-convex, auriculate rugosochonetids having semi- circular to subquadrate outline; widest at hinge. Sides sloping, width slightly greater than length. Surface ap- parently smooth, pseudo-costellate when decorticated (pseudo-costellae numbering eight in 1 mm distance at about midvalve). Very slight dorsal fold and ventral sulcus. Commonly six hinge spines on either side of beak. Ventral valve high to globose, greatest height at about midvalve. Lateral commissure having slight dor- sad flexure just anterior to well-defined ears. Interarea low, wide, apsacline. Dorsal valve concave, having dorsad flexure just anterior to ears; lowest point mesial. Interarea re- flexed, anacline to hypercline. Ventral interior having large, anteriorly directed hinge teeth, triangular in section, unsupported by den- tal plates. Boss of callus shell material, anteriorly rounded, filling delthyrial apex, merging ventrally and anteriorly into short median ridge. Ridge low, rather broad, notched where it meets valve floor, continuing anteriorly to about one-third valve length as low me- dian myophragm, dividing well-defined, inset, ovate, smooth to striate muscle attachment scars. Remainder of surface finely papillose, papillae in radial rows near- er margins. Dorsal interior having mesially slit, quadrilobate to hexalobate cardinal process myophore, subcircular in posterior aspect, lateral and ventral lobes posteriorly slightly cuspate. Slight chilidial boss as spinelike pro- trusion from dorsal extremity of myophore. Deep, well-defined submyophoral alveolus. Hinge sockets deep, well-defined by small, swollen outer socket ridges and large laterally widening inner socket ridges that diverge slightly from hingeline. Anderidia distinct, low, anteriorly bearing a few stout endospines. Me- dian septum arising at alveolus, continuing anteriorly as low rounded ridge, becoming narrower and more marked opposite and anterior to ends of anderidia, © ending at or slightly anterior to midvalve. Muscle at- tachment scars indistinct. Remainder of surface finely © papillose, radially striate where decorticated. Measurements (in mm).— Height Hinge Mid- or Thick- Length Width Width ness Material LOcALITy 4 USNM 221047 5.5 10.2 73 2.3 (articulated valves) USNM 221049 6.0. 10.8h¢ 9.0, Dall (ventral valve) USNM 221053 6.6 10.2, 7.0, 2.5 (ventral valve) LocaLity 8 MMH DG-S508 5.0, 8.0, 7.0 2.0 (articulated valves) USNM 221048 6.0 10.0 8.0 PHD) (articulated valves) USNM 221051 6.5 9.6 Tee 2.0 (ventral valve) Loca.ity 13 USNM 221046 PUSS 5.0 35) 0.8 (ventral valve) USNM 221050 6.2, 11.4 8.4, Pes (ventral valve) USNM 221052 6.5, 10.2, WSs DT (ventral valve) USNM 221054 8.2 13.8, 9.7 3.0 (dorsal valve) USNM 221055 8.3, 12.2 7.6. 5 (ventral valve) Occurrence.—Chonetinetes cf. C. varians has been recovered from localities 4, 8 and 13 in the present collections from the Palmarito Formation. In the West Texas area, C. varians is known only from the three lower members (Hegler, Rader and Lamar) of the Bell Canyon Formation (Late Guadalupian), though the in- dividuals most similar to the Venezuelan specimens are limited to the Hegler Member. This age is younger than that obtained from other parts of the fauna at. those localities. | Diagnosis.—Small, moderately convex Choneti- netes, resembling C. varians Cooper and Grant (1975) but lacking the strong ventral sulcus of that species. | Types.—Figured Specimens: USNM 221048, USNM. 221051, USNM 221056; Measured Specimens: USNM_ 221046—221055, MMH DG-S08. | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 55 Comparison.—Chonetinetes cf. C. varians is easily distinguished from all other Palmarito chonetaceans by its concavo-convex form, its smaller size and far more conservative interiors. Sfauromata esoterica n. gen. and sp., is larger, less globose, and has a more endospinose interior. The same may be said for Dy- oros acanthopelix n. sp., although the interior orna- ment of that form is not so striking as that of S. eso- terica. It is more difficult to distinguish it from West Texas species of Chonetinetes. C. varians may be distinguished from C. angusti- sulcatus Cooper and Grant (1975) on the basis of the very small size and narrow ventral sulcus of the latter. It may theoretically be distinguished from the type species of the genus, Chonetinetes reversus Cooper and Grant (1969), by having a strong ventral sulcus. Most of the West Texas specimens assigned to C. var- ians do have such a feature, but some, including a figured paratype of the species (USNM 153677b) do not. Specimens from locality 732a [Hegler Member of the (Capitanian) Bell Canyon Formation] consist in part of essentially asulcate forms, of which the cited paratype is one. In these asulcate forms the dorsal valve does not exhibit the subconical taleolar mounds flanking the median septum that are supposedly char- acteristic of the genus. It is these atypical forms that are here identified with the Palmarito specimens, not the majority of more typical West Texas C. varians. Discussion.—Since the characters of minor sulca- tion and dorsal valve interior conservatism are best expressed in the earliest representatives of the species, it would be tempting to suggest that they rep- resent a genetic variant, perhaps worthy of a new spe- cific designation. C. varians is, however, such a rare form, that no such conclusions can confidently be drawn. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 4 1 — 2 fine silicification 8 2 1 1 fine silicification 13 — 2 4 fine silicification Suborder PRODUCTIDINA Waagen, 1883 Superfamily AULOSTEGACEA Muir-Wood and Cooper, 1960 Family AULOSTEGIDAE Muir-Wood and Cooper, 1960 Subfamily ECHINOSTEGINAE Muir-Wood and Cooper, 1960 Genus XENOSTEGES Muir-Wood and Cooper, 1960 Type Species.—Xenosteges adherens Muir-Wood and Cooper, 1960, p. 112, pl. 10, figs. 1-13. Diagnosis.—Nearly smooth Aulostegidae, generally of small size, having rhizoid spines only and promi- nent, commonly elevated brachial ridges and dorsal adductor scars. Occurrence.—Several species of Xenosteges are known from the West Texas area in rocks ranging in age from Late Wolfcampian to Late Guadalupian (Capitanian). Two specimens questionably assigned to the genus have been reported from Thailand (Water- house and Piyasin, 1970) in rocks correlated to the Cathedral Mountain Formation of the West Texas area (Grant, pers. comm., 1974). Comparison.—Xenosteges is easily distinguished from other genera of the Echinosteginae by its total lack of ornament spines, all spines being of rhizoid habit and involved intimately in the attachment of the shell to the substrate. Strophalosiella Likharev (1935) lacks ornament spines as well, but it is finely costellate on both valves, while Xenosteges is lamellose to weakly rugose. Xenosteges may be distinguished from the similarly aspinose strophalosiid genus Heteralosia R. H. King (1938) by the presence of teeth and sockets in that form. It is distinguished from another small aulostegacean, Atelestegastus Cooper and Grant (1975), by the consistently narrower hinge and fine ornament spines of that form. Discussion.—Xenosteges, by virtue of its total lack of ornament spines and its lamellose to weakly rugose ornament should be readily recognizable in Permian faunas. One obstacle to this recognition may be its small size. If the Thai specimens are indeed improp- erly assigned to the genus, its absence outside the Western Hemisphere Tethyan realm may indicate that the genus is longitudinally as well as latitudinally en- demic. Xenosteges minusculus new species Plate 4, figures 3-18 Etymology of Name.—L. minusculus = diminu- tive. Description.—Small to minute, very small for ge- nus, unequally biconvex to concavo-convex, having wide straight hinge. Operculiform dorsal valve deeply inset into marginally flanged cup-like ventral valve. Outline subcircular to semicircular. Umbonally ce- mented to substrate; circlet of rhizoid attachment spines along ventral hinge and umbo. Few propping spines higher up anterolateral slopes of ventral valve. Surface smooth or concentrically wrinkled. Attach- ment plane at variable angles to plane of commissure, commonly approaching or exceeding 90° in mature specimens. Ventral valve deep, cuplike, with wide flange sur- rounding smaller dorsal valve. Flange commonly everted to approximate plane of commissure. Umbo commonly flattened, thinned or missing. Interarea very low, having tiny open delthyrium. Ears variably expressed, tapering gradually anteriorly into flanges. Commonly widest at midvalve, slightly less wide at hinge; deepest at midvalve. Flanks gradually sloping anteriorly and laterally, cut off abruptly posteriorly at attachment scar. Dorsal valve commonly subcircular to semicircular in outline. Immature valves convex; mature valves commonly concavo-convex, having convex umbonal region, raised margin and intervening concentric fur- row. Surface concentrically wrinkled and dimpled; no spines. Posteromesial projection of lophidium closing delthyrium of ventral valve. Ears small, very thin, tri- angular. Ventral interior having triangular median umbonal rise, providing attachment for paired adductor mus- cles. Thickened marginal ridge extending from either side of delthyrium toward flanges, longitudinally grooved; groove articulating with corresponding ridge BULLETIN 313 in dorsal valve. Hinge spines hollow, bases open, communicating to exterior. Dorsal interior having prominent marginal ridges arising at base of cardinal process, slightly thickened posteriorly to form ridges that articulate with grooves in marginal ridges of ventral valve. Ridges continuing around entire valve in some specimens, anteriorly commonly expressed as abrupt dorsad deflection of valve surface. Cardinal process on stout, short shaft, bilobate or secondarily quadrilobate; myophore lobes closely appressed or splayed. Submyophoral alveolus present, produced anteriorly as shallow furrow; fur- row healed anteriorly to produce narrow, anteriorly raised median septum. Septum terminating posterior to midvalve, often as pointed projection above valve floor. Septum flanked posteriorly by paired inset pos- terior adductor scars; surfaces of scars commonly tilt- ed posteriorly from plane of valve floor. Brachial ridges of productoid type, given off horizontally, com- monly elevated and strong, terminating in circular mounds at or posterior to midvalve. Interior surface — otherwise smooth, except anteriorly endospinose in some specimens. Endospines small, apparently in a few concentric rows near margins. Measurements (in mm).— | VENTRAL VALVE DorsAL VALVE Ventral Hinge Maximum Hinge Maximum Thick- Valve Length Width Width Length Width Width ness Height USNM 221057 2.3 De, 2.5 1.9 1.8 2.0 0.8 1.2 USNM 221058 Ths 2.5 3.0 2.7» 2.0 DES 1.0 1.7 USNM 221059 2.8 2.8 3.4 25 2. 2.8 1.0 1.2 USNM 221060 3°56 3.2 4.1 2.5 2.5 2.8 1.7 3.0 USNM 221061 BF2 4.0, 4.0 2.7 3.6), 3.1 1.2 2.0 USNM 221062 3.5 4.4 5.1 2.9 322 3.5) 2.3 3.7 (holotype) Occurrence.—Xenosteges minusculus has been re- covered only from locality 6. It is common in block A, rare in block B and abundant in block C. Diagnosis.—Very small Xenosteges having reduced ears, strong dorsal interior marginal ridges and round- ed, posteriorly set brachial ridges. Types.—Holotype: USNM 221062; Figured Speci- mens: USNM 221057-221059, USNM 221062—221071; Measured Specimens: USNM 221057—221062. Comparison.—Xenosteges minusculus is easily dis- tinguished from all other known species of the genus by its smaller overall size, the largest specimen being slightly over five mm in its largest dimension. In ad- dition, it is distinguished from X. adherens Muir- Wood and Cooper (1960), X. anomalus Cooper and Grant (1975) and X. trivialis Cooper and Grant (1975) by its relatively narrow hingeline, compared to those prominently auriculate forms. It lacks the ventral sul- cus of X. magnus Cooper and Grant (1975), and is more equidimensional than the commonly elongate X. umbonatus Cooper and Grant (1975). Of the described species of Xenosteges, X. minusculus probably most closely resembles X. quadratus Cooper and Grant - (1975), from which it differs in the smaller, more me- sially appressed brachial ridges and the umbonally © concave dorsal valve of that form. | Discussion.—Xenosteges minusculus is the first re- | ported occurrence of the genus outside of the West i Texas area, with the exception of two specimens from’ Thailand questionably assigned to the genus (Water- house and Piyasin, 1970). Material.— | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation 6 (block A) 13 23 11 fine silicification 6 (block B) 3 2 1 fine silicification 6 (block C) 15 115 74 fine silicification Family COOPERINIDAE Pajaud, 1968 Subfamily COOPERININAE Pajaud, 1968 Genus COOPERINA Termier, Termier and Pajaud, 1966 Type Species.—Cooperina inexpectata Termier, Termier and Pajaud, 1966, pp. 332-335. Diagnosis.—Cooperininae bearing spines on both valves, flangelike dorsal submarginal ridge, short but prominent dorsal anteromedian ridge and elevated, excavate adductor platforms. Occurrence.—Cooperina is known in rocks of Penn- sylvanian and Permian age, from every continent but Africa, Australia and Antarctica. Its occurrence ap- pears to be limited to the Tethyan realm during the Permian. It first appears, reported as Leptalosia spon- dyliformis White and St. John (1867) [in Dunbar and Condra (1932)], in the Pawnee Formation (Laberdie Limestone Member) of Late Desmoinesian age, from Oklahoma. It is next seen in Thailand, in the Early Permian of Ko Muk, as C. polytreta Grant (1976). C. triangulata Cooper and Grant (1975), from the Lower Wolfcampian of the West Texas area is another Early Permian form. C. parva Cooper and Grant (1975) is found at various localities in the Leonardian of West Texas, while C. subcuneata Cooper and Grant (1975), is at present limited to the Upper Leonardian of that area. C. inexpectata has been recovered from various localities from the Guadalupian of West Texas, and | from locality 6, blocks A, B and C in this study of the | Palmarito Formation. A form recognized as belonging to the genus has been recovered from the Upper Perm- | ian Zechstein of Germany (Grant, 1976, p. 89). _ Comparison.—Cooperina is with great difficulty distinguished from Ansehia Termier and Termier (1970), and indeed the two genera are probably closely related. Only the apparent absence of dorsal spines and the latest Permian (Dzhulfian) age of the Cambo- dian genus support the idea that they are distinct taxa. A definitive decision must await development of the internal details of Ansehia. Atelestegastus Cooper and Grant (1975), lacks any ornament spines or an antero- median ridge in the ventral valve interior, and pos- sesses a characteristic wide flange around the cup-like ventral valve, surrounding the inset dorsal valve. Fa- nn — lafer Grant (1972), is easily distinguished by its prom- inent muscle platform and its calcified ptycholophous brachidium in the dorsal valve. Discussion.—Cooperina was originally suggested (Pajaud, 1968) as the ancestor to extant thecidian bra- chiopods (e.g., Thecidellina). Subsequent studies (Cooper and Grant, 1969; Grant, 1972; Cooper and Grant, 1975; Grant, 1976) have demonstrated its prop- er placement within the Productidina. Cooperina inexpectata Termier, Termier and Pajaud Plate 4, figures 19-37 Cooperina inexpectata Termier, Termier and Pajaud, 1966, p. 332, fig. 1; Cooper and Grant, 1969, pl. 3, figs. 14-27; Cooper and Grant, 1975, p. 824, pl. 210, figs. 1-61; pl. 212, figs. 11-22. Description.—Small to minute Cooperina having straight hingeline, deeply concave ventral valve and convex to concavo-convex dorsal valve. Rhizoid at- tachment spines in circlet around ventral umbo and on ears of ventral valve; crudely parallel rows of exterior ornament spines; common on ventral valve, rare on dorsal valve. Plane of commissure horizontal to ver- tical, with respect to substrate, becoming more verti- cal with growth. Ventral valve outline ovate to subquadrate in dorsal aspect. Umbonal region commonly modified or miss- ing, depending on form of substrate. Attachment spines densely packed, conforming to substrate; or- nament spines straight or slightly curved, commonly at low angle to surface, inclined toward plane of com- missure. Interarea moderately high, commonly 0.15 of shell length (Range: 0.11 to 0.21 in 12 specimens), commonly orthocline to apsacline, very thin, over- hanging posterior margin of dorsal valve to form grooved hinge insertion. Broad ears gradually tapering anteriorly, in dorsal aspect producing egg-shaped out- line of visceral cavity. Thickened lateral and anterior margins forming rim around inset dorsal valve margin. Anterior margin, rounded, straight or very slightly in- dented mesially. Dorsal valve subquadrate, elongate rectangular or rounded in outline, with or without slight anteromesial indentation. Surface smooth to wrinkled, convex pos- teriorly, concave anteriorly in more mature individu- als. Ears tiny, thin, delicate, acuminate triangular. Ventral interior deeply concave, of variable form depending on attachment surface; umbonal region commonly flattened or missing. Muscle scars indis- tinct, on either side of low umbonal mound or broad ridge. Umbonal mound merging anteriorly and dor- sally into low, variably expressed median ridge. Ridge broadening anteriorly, continuing to anterior margin, 58 BULLETIN 313 effectively dividing valve into two lobes, and articu- lating with anteriorly divided anteromedian ridge of dorsal valve. Dorsal interior having thin, flangelike submarginal ridges, arising laterally at base of cardinal process, running just inside valve margins to reach highest point at about midvalve, there turning anteromesially and becoming lower toward the anterior margin, there continued as a single row of small, low pustules. Ridges re-arising mesially, recurving posteriorly to conjoin near midvalve as high, anterodorsally grooved median ridge. Median ridge gradually sloping ante- riorly, sharply cut off posteriorly, merging into distinct narrow median furrow nearer hingeline. Submarginal ridges commonly (49 of 59 specimens) highest poste- rior to highest point of anteromedian ridge; submar- ginal ridges commonly (in 52 of 59 specimens) lower than anteromedian ridge; neither relationship corre- lated to growth stage. Delicate bilobate cardinal pro- cess myophore set on short slender shaft, shaft at an- gle to valve plane, allowing insertion below ventral interarea. Myophoral lobes moderately splayed, dor- soposteriorly cleft, producing effective quadriloba- tion. Thin, obliquely-oriented adductor platforms set in posterolateral corners of valve, attached laterally to inside walls of submarginal ridges and posteriorly to valve floor, merging posteriomesially into broad, ridge-like bases of cardinal process shaft. Brachial ridges poorly defined, elongate. Measurements (in mm).— VENTRAL VALVE DorsAL VALVE Inter- Total Maximum area Hinge Maximum Thick- Length Width Height Length Width Width ness LOCALITY 6 (block C) USNM 221072 1.8 1.8 0.2 1.4 0.6 1.5 0.4 USNM 221073 23 1.9 0.3 2.0 1.0 1e7/ 0.8 USNM 221074 2.6 2 0.3 De, les Dp) 0.3 USNM 221075 2) 2.8 0.4 2.6 1.2 23 1.2 USNM 221076 a2 2.8 0.5 2.3 1.4 D2 1.1 USNM 221077 33-3) 3.4 0.5 2.5 1.7 2.6 1.1 USNM 221078 3.4 2.4 0.5 DES ia 2.3 11-33 USNM 221079 3.4 3.1 0.7 2.4 1.6 2.3 1.6 USNM 221080 3.4 3.5 0.6 2.6 1.7 B03 2.0 USNM 221081 3t5 3.0 0.5 2.5 1.8 22. 1.6 USNM 221082 3.6 2.9 0.6 2S 123 2.2 2.0 USNM 221083 3.6 3.0 0.6 2.6 1.4 2.3 1.6 Occurrence.—Cooperina inexpectata is known from rocks of Guadalupian age in the West Texas area. The specimens herein described constitute the other known occurrence of the species. Individuals have been recovered only from locality 6, blocks A, B, and C. They are common to abundant in blocks A and C, but are rare in block B. Diagnosis.— Rectangular to square Cooperina having long curved ornament spines, a broad attachment area on the pedicle valve and strongly elevated median ridge in the brachial valve. (Cooper and Grant, 1975, p. 825) Types.—Figured Specimens: USNM 221075, USNM 221079, USNM 221084, USNM 221086, USNM 221092, USNM 221104, USNM 221112, USNM 221117, USNM 221118, USNM 221121, USNM 221132, USNM 221142-221146. Measured Specimens: USNM 221072-221142. Comparison.—Cooperina inexpectata is easily dis- tinguished from the only other Palmarito brachiopod of similar form and size, Xenosteges minusculus n.— sp., by its more elongate form and its strikingly dif- ferent interior details. It may be distinguished from other species of Cooperina with somewhat more dif- — ficulty. It is distinguished from C. swbcuneata Cooper and Grant (1975) by the narrow hinge and conspicuous ~ brachial pits in that form. It is generally larger and less triangular than C. triangulata Cooper and Grant (1975) | and has ornamental spines, which that form lacks. It” is similarly distinguished from C. spondyliformis — (White and St. John, 1867). C. parva Cooper and — Grant (1975) bears close resemblance to juvenile and apparently neotenous (large but with low dorsal me- | dian and submarginal ridges) individuals of Cooperina © inexpectata from the Palmarito Formation, but is not placed in synonymy here because the two species do! not overlap in many taxonomic characters in the West! Texas area where they were defined. i Discussion.—The dorsal valve of Cooperina, prob- | ably less affected by local environmental variables i PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 59 (substrate type, site of attachment, etc.) than the ven- tral may be defined in outline by three measurable variables: hinge, or minimum width, maximum width, and length. Some concept of the shape variability of the species can be gained through a plot, on a trian- gular diagram of these variables, normalized to 100% (Text-fig. 9). This diagram shows four variability fields. The point within each defines the position of the mean of the indicated variable: the polygon sur- rounding that point extends one standard deviation to each side of the mean, and the dotted line surrounding the polygon is a measure of the range of variation of the form described. The data on which the illustration is based are presented as Table 9. The numerical trans- formations employed are summarized in Table 10. In terms of outline of the dorsal valve, the four forms are clearly related. There is considerable over- lap between the Venezuelan forms (C & D), which are here considered as different ontogenetic stages of the same species. There is no overlap between the ranges of variation in shape of the two West Texas forms (A & B), but it is readily apparent that they are related in much the same manner as are the Venezuelan forms, though not so closely. LENGTH (%) = ne | MIN. WIDTH (%) 31 27 23 19 15 Text-figure 9.—Shape variation of dorsal valves of four samples of Cooperina from the Permian of West Texas and Venezuela. Field surrounded by ------ = Cooperina inexpectata from West Texas; field surrounded by ------ = Cooperina parva from West Texas; field surrounded by —:—-—:— = mature Cooperina inexpectata from Venezuela; field surrounded by —— = apparent immature Coop- erina inexpectata from Venezuela. (Within each field, the coded line surrounds all data points; the polygon defines one standard devia- tion on each side of the mean for all three variables; the point within each polygon is the mean for all three variables. Data are summa- |rized in Tables 9 and 10.) One possible resolution of this situation might be to designate three species: C. inexpectata, as typified by the West Texas forms (field A), C. parva, again typ- ified by West Texas specimens (field B), and a new Venezuelan species of Cooperina. This strategy is not employed because there is no obvious morphological difference between C. inexpectata of West Texas and the mature Venezuelan forms that cannot be explained in terms of normal infraspecific variation. Since forms transitional between juvenile and mature individuals are observed in the Venezuelan collections, it is rea- sonable to combine them as a single species. It cannot be determined whether the juvenile ontogenetic stage seen in Venezuela is genetically related to the appar- ently neotenous species of C. parva of West Texas. It is, however, reasonable to consider similar mor- phologies in fossils as representing ontogenetically distinct but genetically conspecific organisms in one place and time, while they represent genetically dis- tinct species in another. Geographic and temporal sep- aration are recognized factors in speciation. Family RHAMNARIIDAE Muir-Wood and Cooper, 1960 RHAMNARIIDAE cf. Ramavectus sp. Plate 4, figures 38, 39 cf. Ramavectus Stehli, 1954, p. 327 ff. Types.—Figured Specimen: USNM 221147. Discussion.—A single poorly preserved specimen recovered from locality 11 is questionably referred to Ramavectus. It is largely decorticated, the only re- maining shell material being several pieces of ventral valve surface, the ventral beak and the proximal por- tion of the dorsal umbo. The umbonal region has been silicified as a unit, so that the form of the cardinal process is lost. Grinding the umbonal region did not reveal the presence of the large median septum char- acterisitc of Tschernyschewia Stoyanov (1910). The absence of a distinct cicatrix of attachment suggests that it does not belong in either Rhamnaria Muir- Wood and Cooper (1960), Spuriosa Cooper and Grant (1975) or Juresania Frederiks (1928), externally simi- lar forms. In addition, most species of Rhamnaria are smaller, and none bears the distinctive regularly spaced elongate spine bases on the ventral valve that in Ramavectus, and the Palmarito specimen, suggest periodically interrupted costae. The specimen might be mistaken on casual inspection for a large species of Bathymyonia Muir-Wood and Cooper (1960), but the presence of a true interarea in the Palmarito form clearly removes it from the Echinoconchidae. 60 BULLETIN 313 Table 9.—Measurements of dorsal valves of Cooperina inexpectata Termier, Termier and Pajaud (1966) from locality 6, Palmarito For- mation. SMRH = Submarginal Ridge Height MRH = Median Ridge Height SMRD = Distance from highest point on submarginal ridge to anteriormost point of shell, measured parallel to shell length. MRD = Distance from highest point on median ridge to anteriormost point on shell, measured parallel to shell length. Hinge Minimum Maximum Length Width Width Width SMRH MRH SMRD MRD (block A) USNM 221084 2.4 1.0 1.0 2.6 0.6 1.0 1.3 1.1 USNM 221085 2a 1.0 1.0 2.2 0.6 0.5 1.1 0.7 USNM 221086 2.1 1.4 1.3 2.0 0.7 1.1 1.6 1.1 USNM 221087 2.1 1.4, 1.3, 2.1 0.6 0.7 ED 1.0 USNM 221088 Dal 1.5 3 2.0 0.7 1.0 1.4 1.0 USNM 221089 D2 0.9 0.9 1.9 0.4 0.7 12 0.7 USNM 221090 2.2 1.4 1.2 2.0 0.6 0.8 0.9 0.7 USNM 221091 2.2 1.4, 1.1, Dl 0.6 0.7 1.4 0.9 USNM 221092 2D. 1.3 1.2 2.2 0.7 0.9 122 0.8 USNM 221093 2.2 1.4 13} 2.4 0.9 0.9 1.2 1.0 USNM 221094 23 isa 1.6 2.3 0.6 1.0 1.3 1.0 USNM 221095 23 1.2 152 2.4 0.6 0.9 0.8 1.0 USNM 221096 2.3 1.3, 113} 2.4 0.8 1.3 1.6 1.1 USNM 221097 233) 2.1h 1.9, 2.6 0.7 0.7 1.4 1.1 USNM 221098 2.4 1.6 1.5 2.2 0.7 1.0 1-5) 1.0 USNM 221099 2.4 2.0 1.6 Deg) 0.7 0.9 1.1 EV } USNM 221100 2.4 0.9 0.9 2.3 0.6 0.9 [3 1.3 USNM 221101 2.4 1.3 1.1 23 0.6 0.9 1.6 ilcil USNM 221102 2.4 1.3 i1.3) 2.3 0.6 iol 1.3 1.0 USNM 221103 2.4 1.3 1.3 2.4 0.7 1.1 1.2 0.9 USNM 221104 2.4 1.3 1.3 2.4 0.8 ito 1.6 1.4 USNM 221105 2.4 1165) 1.4 DES 0.7 1.0 1.3 1.2 | USNM 221106 2.4 1.6 (les) 2S 0.9 1.1 iL) 1.4 } USNM 221107 2.4 1.0 1.0 2.6 0.6 1.0 1.3 1e1 | USNM 221108 2S 1.8 1.4 2.0 0.6 0.9 1.8 0.9 | USNM 221109 DES 1.4, es) 29) 0.7 1.1 1.9 13 USNM 221110 2S 1.0 1.0 2.4 1.0 1.2 i133 151 USNM 221111 2.5 1.5 1.4 2.4 0.8 1.2 1.2 12 USNM 221112 DES 1.4 13) 2.5 0.9 1.5 eS 12 i USNM 221113 3) 1.8 1.4 DES 0.6 1.0 1.6 ila USNM 221114 2.5 1.9 1.8 2.6 0.7 1.0 iL) 1:2 USNM 221115 2.6 eS) ity 2.3 0.6 0.7 1.6 1S USNM 221116 2.6 1.8, 1.8), Del 0.8 1.0 FD IBS) (block C) USNM 221117 1.4 1.0 0.9 1.7 — 0.1 _ 0.5 USNM 221118 1.6 1.3 1.3 1.9 0.4 0.3 0.9 0.3 USNM 221119 1.8 1.4 1.3 DD 0.2 0.1 _ 0.6 USNM 221120 1.9 1.3 1.1 2.0 0.3 0.7 1.1 0.7 USNM 221121 1.9 1.5 1.5 2.1 0.4 0.6 1.3 0.6 USNM 221122 2.0 1.4, 1.2, 2.3 1.1 0.9 1.4 0.8 USNM 221123 Dy 1.4), 1.4, 1.9 0.8 0.9 1.2 0.8 USNM 221124 ep) 1.5 1.3 1.9 0.6 0.7 1.0 0.6 USNM 221125 2.2 1.1 1.1 YG) 0.3 0.6 1.5 0.8 USNM 221126 2.2 1.5 1.4 252 0.6 0.7 118) ile USNM 221127 2.2 1.05» 1.0pn 2.4 12 1.2 1.1 0.9 USNM 221128 ED 1.8, led 2.4 0.6 0.6 1.3 1.1 USNM 221129 2.3 1.8, 1.4, 2.3 0.6 0.9 1.4 0.9 USNM 221130 253 i163} 1.3 3} 0.7 0.9 Nez 0.8 USNM 221131 2.3 s1-5) 1-5) 2.4 0.7 1.1 1.3 1.0 USNM 221132 DES, 1.9 1.8 2.6 0.4 0.7 1.4 0.8 USNM 221133 2.4 1.0 1.0 223 0.8 1.2 ile? 1.0 USNM 221134 2.4 1.6 1.6 2.4 0.8 1R2 1.6 1.1 USNM 221135 2.4 1.4 1.4 2.6 1.0 1.1 (lez) 1.0 PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER Table 9.—Continued. SMRH = Submarginal Ridge Height MRH = Median Ridge Height SMRD = Distance from highest point on submarginal ridge to anteriormost point of shell, measured parallel to shell length. MRD = Distance from highest point on median ridge to anteriormost point on shell, measured parallel to shell length. Hinge Minimum Maximum Length Width Width Width SMRH MRH SMRD MRD USNM 221136 2.4 i E7/ 2.6 1.0 1.4 71 2 USNM 221137 2.5 1.8, 1.7, 2.5 0.6 0.9 1.4 1.1 USNM 221138 755) 1.8), 1.4, 2.6 0.6 0.9 iss) 1.0 USNM 221139 2.5 1.6 1.6 2.6 0.6 1.2 1.3 i 72 USNM 221140 2.6 hail 1.1 2.9 0.9 1,72 1.0 1.2 USNM 221141 Dell aa 1.9 2.6 0.9 1.1 1.5 ile USNM 221142 2.8 Dal 1.9 2a3) 0.6 1.0 1.7 1.0 Table 10.—Statistics calculated from measurements of dorsal valves of two species of Cooperina Termier, Termier and Pajaud (1966). Cooperina inexpectata Mature individuals from West Texas 9 specimens [USNM 152637a-i] Cooperina parva Mature individuals from West Texas 6 specimens [USNM 152638a—c; USNM 152639d, e, g] | Cooperina inexpectata Mature individuals from Venezuela 53 specimens USNM 221133-221142] Cooperina inexpectata Apparent juvenile individuals from Venezuela 6 specimens [USNM 221117-221121, USNM 221132] [USNM 221084-221116; USNM 221122-221131; Measured Calculated Value Parameter Statistic (in mm) Hinge Width mean 2.30 standard deviation 0.59 range 1.3-3.0 Maximum Width mean 3.14 standard deviation 0.65 range 2.0-4.2 Length mean 3.46 standard deviation 0.71 range 2.3-4.5 Hinge Width mean 1.28 standard deviation 0.29 range 1.0-1.8 Maximum Width mean 1.95 standard deviation 0.35 range 1.5-2.4 Length mean 1.40 standard deviation 0.11 range 1.2-1.5 Hinge Width mean 1.35 standard deviation 0.27 range 0.8—2.1 Maximum Width mean 2.34 standard deviation 0.21 range 1.9-2.9 Length mean 2.35 standard deviation 0.17 range 2.0-2.8 Hinge Width mean 1.32 standard deviation 0.31 range 0.9-1.8 Maximum Width mean 2.08 standard deviation 0.31 range 1.9-2.6 Length mean 1.82 standard deviation 0.31 range 1.4-2.3 62 BULLETIN 313 The roughly triangular outline, small ears, bunch of fine spines along the hinge, short hingeline, distinct interarea and peculiar spine arrangement clearly sug- gest placement of this form within the Rhamnariidae, but do not permit more than tentative assignment to the genus Ramavectus. Superfamily PRODUCTACEA Gray, 1840 Family MARGINIFERIDAE Stehli, 1954 Subfamily COSTISPINIFERINAE Muir-Wood and Cooper, 1960 Genus ECHINAURIS Muir-Wood and Cooper, 1960 Type Species.—Echinauris lateralis Muir-Wood and Diagnosis.— Costispiniferinae ornamented by spines and spine ridges on ped- icle valve and spines and dimples on brachial valve, lateral halteroid spines long and extended laterally. (Cooper and Grant, 1975, p. 1000) Occurrence.—The various species assigned to the genus Echinauris have been recovered from rocks ranging in age from earliest Wolfcampian to Early Guadalupian equivalents. It has been reported from West Texas (Muir-Wood and Cooper, 1960; Cooper and Grant, 1975), Guatemala (Stehli and Grant, 1970), Greece (Grant, pers. comm., 1974), Tunisia (Termier and Termier, 1957), Pakistan (Grant, 1968), Nepal? (Waterhouse, 1966), China (Chao, 1927), Thailand (Waterhouse and Piyasin, 1970; Grant, 1976) and Ti- mor (Broili, 1916). Comparison.—Echinauris is distinguished from El- liottella Stehli (1955) and Oncosarina Cooper and Grant (1969) by the lack of dorsal exterior spines in the latter forms; from the Asian genus Haydenella Reed (1944) by the paucispinose ventral valve of that form; from Costispinifera by the greater spine density and anterior ventral costation of that form; from Both- rionia Cooper and Grant (1975) by the fold-sulcus de- velopment and ventral marginal rim of that form. The most readily apparent diagnostic characters of Echi- nauris are the aspinose “‘denuded”’ ventral umbonal region, the centripetally-directed dorsal spines, and the absence of strong radial ornament on either valve. Discussion.—Echinauris has not been reported from Australia, southern Africa, or either polar region. In the Permian, it appears to have had a Tethyan (‘“‘trop- ical’’ to ‘‘subtropical’’) distribution. Echinauris bella Cooper and Grant Plate 4, figures 40-55; Plate 5, figures 1—2 Echinauris bella Cooper and Grant, 1975, p. 1003, pl. 326, figs. I- 58; pl. 410, figs. 9-13. Description.—Small, less than average-sized for ge- nus, concavo-convex shells; ovate outline interrupted by ventral ears. Commonly widest at hinge, but ears delicate, commonly broken or missing. Umbo swollen, greatest height at hinge. Both valves spinose; spines long, slender, curving. Anterior margin commonly evenly rounded, rarely slightly sulcate, straight in an- terior view. Surface smooth, having faint concentric wrinkles or faint low costae, produced anterior to spine bases and quickly becoming obsolete anteriorly. Ventral valve convex, having small apical cicatrix of attachment; umbo commonly overhanging long straight hingeline. Umbonal slopes of mature speci- mens bearing spine bases but no spines; delicate um- bonal spines present in attached (cemented) juveniles. Interarea missing, but weak, very low ginglymus spo- radically developed. Single row of posteroventrally directed small spines along hinge; one to several ir- regular rows of spines ventral to hinge. Cluster of long, halteroid spines arising at break in slope of flanks, just ventral to, but not on ears; directed laterally, ventro- laterally, and posteroventrolaterally. Ears narrow, tri- angular, set at a sharp angle to body, not bearing > spines. Ornament spines sheathing remainder of valve, — arising in roughly concentric rows normal to shell sur-— face, turning abruptly anterodorsally following shell” surface; last few generations curving dorsoposteriorly | Over anterior margin. Weak low costae, arising at spine bases, becoming obsolete anteriorly. Dorsal valve concave, semi-circular in outline, hav- ing sloping flanks; commonly auriculate, ears thin, del- icate, rarely preserved; reflexed, lying in plane of com-_ missure. Spinelike lophidium, anterodorsally directed, — projecting slightly beyond hinge. Surface pitted or very rarely bearing numerous short, very fine erect. spines, anteriormost spines centripetally directed. Paired tufts of more commonly preserved, long cen- tripetally-directed straight or slightly curving spines arising on ears and arching over vault of valve. Ventral interior having deep umbonal cavity with low apical longitudinal ridge; ridge in articulated valves lying between lateral lobes of cardinal process. Elongate, anteriorly broadened adductor scars faintly impressed in median valve floor, flanked posteriorly by small, more equidimensional diductor scars. Ears slightly concave, abruptly separated from body cavity by coarsely crenulate ridges. Dorsal interior having characteristic W-shaped car- dinal process myophore, each lobe U-shaped poste- riorly. Lobes appressed dorsally, moderately splayed ventrally; posteroventral extremities somewhat angu-! lar. Myophore set on short stout shaft; shaft bearing median ventral furrow. Weakly crenulate low marginal PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 63 ridges arising at base of shaft, running laterally, rarely continuing to anterior margin. Thin, low breviseptum running anteriorly from furrow of cardinal process shaft, terminating about midvalve. Anterior extremity pointed, free of valve floor in mature specimens, in gerontic specimens having expanded, spatulate, ven- trally directed tip. Anteriorly broad, triangular, ap- parently smooth anterior adductor muscle scars flank- ing median breviseptum, somewhat raised on platforms. Posterior adductor scars smooth, small, elongate oval, somewhat inset into valve floor. Bra- chial ridges given off horizontally, commonly faintly raised, rarely endospinose anteriorly, endospines low. Valve surface very finely pustulose, pustules in radial rows nearer anterior and lateral margins. Measurements (in mm).— Dorsal Valve Hinge Mid- Length Length Width Width Height Locatity 13 USNM 221148 4.5 3.8, 4.0, 4.6 2.0 USNM 221149 Se 4.7 5.0, 6.5, 23 USNM 221150 5.8 5.3 5.0, 6.1 2.7 USNM 221151 6.8 5.8 7.0, 8.0 3.6 USNM 221152 8.0 6.5 7.5» 8.7 39) USNM 221153 8.2 TAO) 7.4, 9.2, 5.0 USNM 221154 8.5 7.0 8.6, 8.9 5.9 USNM 221155 8.6 6.1 6.7, 8.6 5.0 USNM 221156 8.7 6.5 OIE 9.0 525 USNM 221157 8.9 7.0 9.4, 8.7 5.6 USNM 221158 9.0 We2e 8.2, 9.2 5.6 USNM 221159 9.0 7.0 7.0, 9.6 5.6 USNM 221160 9.1 6.9 8.2, 9.1 4.8 USNM 221161 92 6.6 8.9, 8.6 6.7 USNM 221162 9.3 7.0 10.2, 10.0 5.6 USNM 221163 9.6 7.0 8.5, 8.2, 6.0 USNM 221164 9.6 6.7 9.3, 9.0 So) USNM 221165 9.6 US) 10.0, OFF, Sel USNM 221166 10.0 6.5 9.8, 9.2, 6.2 USNM 221167 10.0 Bell 10.0, 10.5 6.0 USNM 221168 10.2 6.9 8.6, 7.9 6.3 USNM 221169 10.3 8.0, 10.6, 9.4 6.9 USNM 221170 11.0 etl 9.0, 9.0 fei USNM 221171 ESS US¥: 10.9, 11.7 7.0 USNM 221172 12.7 8.4 11.7, 11.1, 6.6 Occurrence.—Echinauris bella is found in the West Texas area in the Cibolo and Road Canyon Formations of Late Leonardian age. In the Palmarito Formation it has been recovered from locality 13, where it is by far the most abundant brachiopod. A single well-pre- served dorsal valve of E. bella was recovered from locality 6, block C. Diagnosis.—Small Echinauris, with length and width nearly equal, but hinge commonly greater than midwidth, and scattered spines. Types.—Figured Specimens: USNM 221173221183; Measured Specimens: USNM 221148-221172. Comparison.—The diminutive size of E. bella ef- fectively separates it from E. boulei (Kozlowski, 1914), E. interrupta Cooper and Grant (1975), E. ir- regularis Cooper and Grant (1975), E. lappacea Coo- per and Grant (1975), E. lateralis Muir-Wood and Cooper (1960), E. liumbona Cooper and Grant (1975), E. magna Cooper and Grant (1975), E. productel- loides Cooper and Grant (1975), E. subhorrida (Meek, 1877) and E. subquadrata Cooper and Grant (1975) of the West Texas area. The heavy and sparsely distrib- uted spines of E. crassa clearly differentiate that form from E. bella. The spinose brachial ridges best devel- oped in E. venustula Cooper and Grant (1975) are missing from E. bella, thus distinguishing that form. The Guatemalan species E. huehuetenanguensis Steh- li and Grant (1970) is somewhat larger, and more trans- verse than E. bella. The Asian species E. opuntia (Waagen, 1884) and the Chinese species E. jisuensis (Chao, 1927) are both larger forms than E. bella. The three species E. circularis Cooper and Grant (1975), E. parva Cooper and Grant (1975) and E. venustula exhibit several characters in common: narrow ventral hinge, as compared to the midwidth; variable density and directional development of long thin endospines along the anterior portions of the brachial ridges. Al- though the latter character was mentioned in a dis- cussion of E. bella (Cooper and Grant, 1975, pp. 1003, 1005), I was unable to discover it in specimens referred to the species in the National collections. Discussion.—The Palmarito forms are assigned to the species E. bella, although there are important dif- ferences between them and populations of the species in the West Texas area where it was first described. Text-figure 10 shows variability in form of the ventral valve in samples of E. bella from West Texas and Venezuela, as described by their length, midwidth and height. Although there is considerable overlap of the variability fields of the two samples, the North Amer- ican form has greater length and midwidth compo- nents, while the Venezuelan specimens are propor- tionally higher. This is in part due to the higher proportion of juvenile specimens in the West Texas sample, but even with this bias recognized, the West Texas forms are a bit more transverse than their Ven- ezuelan counterparts. In addition the West Texas forms have finer, more slender spines on both valves and tend to be shallower than the Venezuelan speci- mens. Spine diameter may be a parameter which is covariant with the substrate encountered by the set- tling spat (Grant, pers. comm., 1974). Judging from the development of the median breviseptum of the 64 BULLETIN 313 dorsal valve and the muscle attachment impressions in both valves, none of the E. bella from West Texas appear to have reached the same ontogenetic age as that seen in many gerontic Venezuelan specimens. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 6 (block C) — 1 —_ fine silicification 13 83 50 294 fine silicification Echinauris cf. E. lappacea Cooper and Grant Plate 5, figures 3-12 ef. Echinauris lappacea Cooper and Grant, 1975, p. 1010, pl. 336, figs. 1-31; pl. 476, figs. 1-18. Description.—Small to medium-sized, average-sized for genus, concavo-convex shells; outline transversely oval to transversely rectangular; commonly widest at hinge. Ears small, triangular, delicate, set off from visceral cavity. Umbo low, only slightly swollen, not incurved over hingeline, without apical cicatrix of at- tachment. Both valves bearing spines of various sizes. Anterior margin commonly rounded to slightly in- dented in dorsal aspect; straight in anterior aspect. Ventral valve deeply convex; greatest height com- monly at midvalve. Umbonal slopes bearing spine bas- HEIGHT (%) 44 eee eee es - s MID - WIDTH (%) 46 42 38 34 Text-figure 10.—Comparison of shell form of two population sam- ples of Echinauris bella Cooper and Grant (1975). Dotted lines in- dicate statistics derived from measurements of a West Texas sam- ple; solid lines indicate statistics derived from measurements of a Venezuelan sample; © indicates the mean of the distribution; the polygon surrounds one standard deviation on each side of the mean for all three variables; the ovoid form surrounds all pertinent data points. es but no spines. Low ginglymus present. Several ir- regular rows of spines ventral to hinge and on ears. Spines irregularly scattered over remainder of surface; more densely packed on lateral than mesial slopes, quincunxially arranged or in roughly concentric rows. Spine bases anteriorly somewhat elongate, suggesting costae. Slight mesial sulcus developed in larger spec- imens. Dorsal valve concave; greatest depth anteriorly. Surface dimpled and spinose. Spines in dense wedge radiating anterolaterally from umbo, corresponding in position to break in slope between ears and visceral cavity; also on ears. Less densely packed, more slen- der, centripetally directed spines on remainder of valve exterior. Slight anteromesial fold developed in larger specimens. Ventral interior unknown. Dorsal interior having ‘‘ginglymus,’’ perhaps artic- ulating with negative structure in ventral valve, and pointed small lophidium. Cardinal process small, com- pact, broad-based, W-shaped in posterior aspect, hav- ing disjunct, vertically oriented bladelike lateral lobes and higher, broader ventromesial lobe. Lateral ridges diverging from hinge, continuing only to lateral mar- gins. Alveolus not observed. Cardinal process merging anteriorly into broadened breviseptum; breviseptum separating two pairs of narrowly elongate muscle at- tachment scars. Muscle scars anteriorly raised on plat- forms; surfaces minutely crenulate, sloping postero- laterally. Breviseptum continued anterior to muscle scars as narrow, bladelike ridge, terminating in an- teroventrally directed point just anterior to midvalve. Remainder of interior surface otherwise minutely pus- tulose. Measurements (in mm).— Dorsal Valve Hinge Mid- Length Length Width Width Height Loca.ity 11 USNM 221184 9.6 8.0 10.2, 11.6 6.2 USNM 221185 10.5 8.8 13.5 11.2 7.8 USNM 221186 10.5 8.7 12.1, 11.5 7.9 USNM 221187 Sy 8.5 9.45. 11.8 TAA) USNM 221188 12.0 10.3 16.5), 15.0 i? USNM 221189 12.9pe 10.656 17.0pe 15.5 8.9 USNM 221190 13.5 11.1 16.35. 15.2 WED Occurrence.—E. lappacea is known only from the Road Canyon Formation of the West Texas area. In the Palmarito fauna E. cf. E. lappacea has been re- covered only from locality 11. A Late Leonardian age for this unit is not inconsistent with other faunal evi- dence. | | | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 65 Diagnosis.—Subrectangular Echinauris with low umbonal region, not overhanging hinge, coarse scat- tered ornament spines and thick mat of spines on dor- sal valve. Types.—Figured Specimens: USNM 221185, USNM 221188, USNM 221191-221193; Measured Specimens: USNM 221184—-221190. Comparison.—Echinauris cf. E. lappacea is easily distinguished from E. bella Cooper and Grant (1975), E. circularis Cooper and Grant (1975), E. crassa Coo- per and Grant (1975), E. huehuetenanguensis Stehli and Grant (1970), E. parva Cooper and Grant (1975) and E. venustula Cooper and Grant (1975) by its larger size, and from E. magna Cooper and Grant (1975), E. subhorrida (Meek, 1877), E. subquadrata Cooper and Grant (1975) and E. sp. Stehli and Grant (1970) from the Chochal Limestone of Guatemala, by its smaller size. It is distinguished from E. lateralis Cooper and Grant (1975) by its wider hinge, from E. boulei (Koz- lowski, 1914) by the pronounced ventral costation of that form, and from E. huehuetenanguensis, E. inter- rupta Cooper and Grant (1975), E. liumbona Cooper and Grant (1975) and E. productelloides Cooper and Grant (1975) by the more swollen, incurved umbo of those forms. Of the West Texas forms it most closely resembles E. irregularis Cooper and Grant (1975), from which it differs in its lower umbonal region and more transverse outline. It differs from E. opuntia (Waagen, 1884), from the Salt Range, in its lower umbo and less pronounced ventral costae. Discussion.—The Palmarito specimens cannot def- initely be assigned to the species E. lappacea, because they lack the dorsal endospines characteristic of the species in the West Texas area from which it was first described, because no ventral interiors are available for comparison, and because the suite of specimens is too small to give a fair representation of the range of variation that may be present. monly having greatest width anterior to hinge. Umbo commonly swollen, produced considerably posterior to hinge. Trail long; greatest height commonly anterior to midvalve. Ears small, delicate. Both valves sparsely spinose; dorsal spines very delicate, rarely preserved. Distinct broad ventral sulcus; indistinct dorsal fold. Commissure straight in anterior aspect. Ventral valve deeply convex; tightly spiralled. Umbo high, apex slightly overhanging hinge; umbonal slopes steep; ears small, at sharp angle to body of shell. Median sulcus arising anterior to umbo, con- tinuing to anterior margin. Broad band of spines run- ning up break in slope between ears and umbonal slopes; scattered on flanks; in cluster just ventral to ears, and continuing around anterior margin. Umbo and posterior umbonal slopes non-spinose to sparsely spinose; spines rare in sulcus except anteriorly, low obsolete spine ridges there producing faint costation. Dorsal valve broadly concave; greatest depth at midvalve, commonly markedly transverse. Ears small, delicate; set at sharp angle to body; rarely preserved. Ornament of concentric rugae and dimples; delicate spines present, but rarely preserved. Ventral interior having two pairs of muscle scars in umbonal apex; mesial pair narrow, elongate, appar- ently smooth, set on slight callus platform. Smaller elongate lateral pair of smooth scars set slightly pos- teriorly, not on platforms. Ear baffles developed: slightly raised, interiorly striate; striae directed pos- teroventral-anterodorsal. Ears slightly concave. Re- mainder of surface finely pustulose. Dorsal interior having large trilobate cardinal pro- cess myophore with short shaft. Two pairs of elongate triangular adductor scars flanking posterior portion of narrow breviseptum; breviseptum terminating near midvalve. Rough row of large endospines across an- terior portion of the valve anterior to breviseptum, but indented posteriorly to meet end of breviseptum. Bra- Material.— chial ridges indistinct. ; Measurements (in mm).— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation Dorsal : Valve Mid- 11 19 1 — coarse silicification Length Length Width Height LOcALITy 4 USNM 221211 11.6, 9.1. 14.1 7.4, O a A 221212 14.5 2.0. Bre Se Echinauris cf. E. liumbona Cooper and Grant ee 51013 19.9, - : st i 5 ae Plate 5, figures 13-19 ) pa ma tt cw ay LOCALITY 7 cf. Echinauris liumbona Cooper and Grant, 1975, p. 1012, pl. 337, USNM 221205 12.5 10.5 14.1 De figs. 1-36. USNM 221206 13.9 TS 16.2 9.9 ca bate 2 : 3 USNM 221207 14.9 11.8 14.4 9.3} Description.—Medium-sized, average-sized for ge- USNM 221208 15.0, 114, ise 10.9.. nus, slightly to markedly transverse, concavo-convex USNM 221209 16.Or. 11.0, 15.2 9.4. shells; outline subpentagonal to sub-trigonal; com- USNM 221210 ith. 12.9, 17.8 11.4, 66 BULLETIN 313 Measurements (in mm).—Continued Dorsal Valve Mid- Length Length Width Height LOCALITY 8 USNM 221194 11.6 10.3 15.4 7.6 USNM 221195 12.5 10.8 16.8 8.0 USNM 221196 13.Spe 11.3 16.5 9.1 USNM 221197 13.8 10.9 22.2, 9.By6 USNM 221198 14.5. 12.4, 18.0, 9.0. USNM 221199 14.9 11.4 1Se2) 9.3 USNM 221200 15.4 ES 18.4 9.8 USNM 221201 16. 1p. ES 18.2 10. 1p. USNM 221202 16.4 Pn 21.0, 10.1). USNM 221203 16.64. 13.5. 20.0 11.7, USNM 221204 16.8 1235 17.1 10.9 Occurrence.—Echinauris liumbona occurs in the West Texas area only in the Road Canyon Formation, of Late Leonardian age. In the Palmarito fauna it has been recovered at localities 1, 4, 7 and 8. It is uncom- mon to rare at localities 1, 4 and 8 and common to abundant at locality 7. A Late Leonardian age for the Palmarito localities in which it occurs is consistent with biostratigraphic evidence provided by other fau- nal elements. Diagnosis.—Subrectangular to transverse Echi- nauris with nearly naked umbonal regions, few spine ridges, emarginate anterior and swollen umbo. Types.—Figured Specimens: USNM 221203, USNM 221204, USNM 221213; Measured Specimens: USNM 221194—221213. Comparison.—E. liumbona may be distinguished from E. bella Cooper and Grant (1975), E. circularis Cooper and Grant (1975), E. crassa Cooper and Grant (1975), E. irregularis Cooper and Grant (1975), E. par- va Cooper and Grant (1975), and E. venustula Cooper and Grant (1975) by the smaller average size of ap- parent mature individuals of those forms, and from E. boulei (Kozlowski, 1914), E. magna Cooper and Grant (1975), E. subhorrida (Meek, 1877) and E. subquad- rata Cooper and Grant (1975) by the larger average size of apparent mature individuals of those forms. The comparatively wide hinge of E. interrupta Cooper and Grant (1975), E. lateralis Cooper and Grant (1975) and E. productelloides Cooper and Grant (1975) ef- fectively distinguishes E. liumbona from those forms. E. cf. E. liumbona from the Palmarito Formation lacks the clusters of spine bases on the dorsal ears that are characteristic of E. lappacea Cooper and Grant (1975). On the Venezuelan form, the band of spines below the ventral ears that extends across the anterior margin, is one of its characteristic features. E. cf. E. liumbona is outwardly similar to forms described as — Echinauris sp. (Stehli and Grant, 1970, p. 32, pl. 8, figs. form to allow a more definitive comparison. The spec- imens here referred to E. liumbona also bear external resemblance to an undescribed form (Wardlaw, pers. comm., 1975) from the Gerster Formation (Wordian of Nevada). That form, assignable to the Paucispini- feridae, is generally more spinose, and possesses a complete marginal ridge and well-defined zygidium in the dorsal valve. Discussion.—The Palmarito specimens tentatively referred to Echinauris liumbona have been recovered from four localities within the Palmarito Formation. At localities | and 7, the specimens are preserved by calcite permineralization. Consequently, while well- preserved, they are difficult to prepare in internal de- tail. The forms from localities 4 and 8 are silicified, and internal details may be seen somewhat more clear- ly. The silica replicas of locality 8 are quite coarsely silicified, and fine details are commonly obscured. No dorsal interiors were observed, but details were elu- cidated from partially decorticated shells in which the interior details were expressed in internal molds. At locality 4, however, preservation was fine. A single | partial dorsal valve was recovered, which, although apparently incompletely silicified, showed a typical omega-shaped costispiniferine cardinal process myo- phore, without development of a zygidium. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 5 _ — : F A Get 4 4 1 9 calcite permineralization casts, with some adherent silicified shell y 93 > a calcite permineralization 8 10 — 1 casts, with considerable amounts of adherent silicified shell Family PAUCISPINIFERIDAE Muir-Wood and Cooper, 1960 Discussion.—The elevation of the Paucispiniferidae to family rank (Cooper and Grant, 1975) places it on equal footing with the Linoproductidae and the Mar- giniferidae, with each of which it shares many char- acteristics. The marginal ridge development of the Marginiferidae is commonly found in association with the zygidium, which feature is taken as the most sa- lient diagnostic character of the family Paucispinifer- 19-28) from the Chochal Limestone of Guate- | mala. There are, however, too few specimens of that — PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 67 idae (e.g., in Paucispinifera). Which of the morpho- logic characters displayed by a shell shall be designated as “‘genetically controlled’? and which “environmentally controlled’’ is, in consideration of forms with no living representatives, largely subjec- tive. Internal characters are generally considered to be less affected by environmental variability than are external features, but this is not invariably so. In sum, the assignment of all small Productacea bearing a zy- gidium to the Paucispiniferidae is consciously subjec- tive, and morphologically based. It is hoped that this provisional classification may be refined by more ob- jective future work. Genus ANEMONARIA Cooper and Grant, 1969 Type Species.—Marginifera sublaevis R. E. King, 1931, p. 89, pl. 23, figs. 1Sa—c (non figs. 13, 14, 17 = Anemonaria inflata Cooper and Grant, 1969, p. 8, pl. 5, figs. 28, 29) Diagnosis.— Outline subrectangular, widest at hinge, ears extended; profile deeply concavo-convex; trail with distinct sulcus. Surface nearly smooth except for numerous indistinct costellae on trail; spines few; 1 row on each lateral slope, scattered individual spines on trail and visceral disc. Pedicle valve interior with small sessile cardinal pro- cess with broad zygidium; breviseptum reduced. (Cooper and Grant, 1969, p. 8) Occurrence.—Anemonaria is known from the Bone Spring, Cathedral Mountain and Road Canyon For- mations of the West Texas region. In the present study it has been recovered from localities 1, 10 and 11. The ages represented by the occurrences of the West Tex- as forms are not inconsistent with the other biostrati- graphic indicators for those Palmarito localities. Comparison.—Anemonaria is externally similar to several genera of the Marginiferidae, but differs from all in its possession of a zygidium. Its regularity of form differentiates it from Polymorpharia Cooper and Grant (1975), while its more subdued radial ornament and distinctive spine pattern distinguish it from Lio- sotella Cooper (in Cooper et al., 1953). In its fine, obsolescent ornament, Anemonaria Cooper and Grant (1969) resembles two species of Paucispinifera, P. costellata Cooper and Grant (1975), and P. sulcata Cooper and Grant (1975), in each of which the orna- ment is somewhat more strongly expressed than in Anemonaria. It may be that these forms are more closely related to Anemonaria than their generic as- signment would indicate. Discussion.—The genus Anemonaria was originally based on the type species Anemonaria inflata Cooper and Grant (1969). Various forms which R. E. King (1931) had named Marginifera sublaevis, but not the holotype of that species, were included in the syn- onymy of A. inflata. Later studies of King’s material showed that the holotype of M. sublaevis was, after all, conspecific with A. inflata. Therefore, by the rules of nomenclature A. inflata, became a junior synonym to A. (M.) sublaevis. Cooper and Grant (1975), there- fore so named the species when they described it: Anemonaria sublaevis (R. E. King, 1931). Anemonaria sublaevis (R. E. King) Plate 5, figures 20-27 Marginifera sublaevis R. E. King, 1931, p. 89, pl. 23, figs. 1S5a—c, ?16a, b, 19 (non figs. 13, 14, 17). Anemonaria inflata Cooper and Grant, 1969, p. 8, pl. 5, figs. 28, 29. Anemonaria sublaevis (R. E. King) Cooper and Grant, 1975, p. 1103, pl. 408, figs. 1-26. Description.—Medium-sized, average sized for ge- nus, having transverse rectangular to subpentagonal outline and prominent triangular ears; widest at hinge. Umbo small, low; posterior and anterior slopes steep; greatest height at midvalve. Surface ornament of low, obsolescent costellae; concentric rugae on ears. Ventral valve deeply convex, with no delthyrium. Ginglymus low, poorly developed. Ears flat, in plane of commissure, separated from visceral slopes by sin- gle row of halteroid spines. Additional halteroid spines sparsely distributed over anterior and lateral slopes of valve. Spines very rare along hinge or on ears. Entire surface bearing very low obsolescent costellae; cos- tellae about six in a five mm distance at midvalve, rarely increasing anteriorly by intercalation; becoming more apparent anteriorly. Commissure straight in an- terior aspect. Anterior margin broadly sulcate, sulcus arising anterior to umbo and continuing to commis- sure. Dorsal valve concave; greatest depth anterior to midvalve. Surface generally smooth, non-spinose, but anteriorly faintly costellate, costellae approximating in size those of opposite valve. Ears small, triangular, set at sharp angle to visceral slopes. Small rounded triangular lophidium surmounting low, variably devel- oped zygidium. Margin anteromesially indented, an- teriorly producing low broad fold. Ventral interior having indistinct, apparently striate, paired diductor scars. Lateral walls of umbonal cavity slightly swollen, bearing shallow horizontal grooves; grooves articulating with zygidium of opposite valve. Distinct marginal ridge arising in umbo, continuing around shell near margin, evident anteriorly as low step on interior surface of trail; crenulate across ears on larger specimens. Inner surface smooth in smaller 68 BULLETIN 313 specimens; in larger specimens bearing faint costellae which mirror external ornament. Dorsal interior having small, stout cardinal process without shaft; myophore omega-shaped to triangular in posterior aspect, with small dorsally reflexed me- dian lobe and broad lateral lobes. Mesial portions of lateral ridges at base of cardinal process produced pos- teriorly to form edge of zygidium, articulating with grooves in ventral umbo. Muscle scars indistinct, paired, narrowly elongate. Marginal ridges continu- ous, arising at base of cardinal process, surrounding visceral disc, distally geniculate across ears, distally gradually sloping anteriorly and laterally. Surface an- teriorly and laterally faintly costellate; ornament more pronounced in larger specimens. Measurements (in mm).— Hinge Mid- Length Width Width Height Material Loca.ity 10 USNM 221214 12.0 10.7, 17.4, 6.7, (ventral valve) USNM 221215 12.1, 13.3, 18.0, 5.2, (dorsal valve) USNM 221216 13.7, 16.3, 20.1, 7.0, (dorsal valve) USNM 221217 13.8 16.8, 18.7 8.9, (ventral valve) USNM 221218 15.7 24.0, 22.1, 10.7, (ventral valve) Occurrence.—Anemonaria sublaevis is known from the Bone Spring, Cathedral Mountain and Road Can- yon Formations of the West Texas region. In the Pal- marito Formation it has only been recovered from lo- cality 10, where it is rare. An Early Permian age, based on its occurrence in North America, is not inconsistent with other biostratigraphic indicators in the assem- blage at locality 10. Diagnosis.—Medium-sized Anemonaria having slender halteroid spines and broad ventral sulcus. Types.—Figured Specimens: USNM 221216—221220; Measured Specimens: USNM 221214—221218. Comparison.—Since A. sublaevis is the only species of the genus, no infrageneric comparison is necessary. It may be distinguished from any of the species of Hystriculina Muir-Wood and Cooper (1960), which it resembles in exterior ornament, by its larger size and presence of a zygidium. It may be dis- tinguished from species of Liosotella Cooper (in Coo- per et al., 1953) by the coarser ornament of those forms. It is probably very closely related to Paucispi- nifera sulcata Cooper and Grant (1975), from which it differs only in its more subdued radial ornament, and to Paucispinifera costellata Cooper and Grant (1975), which is distinguished by the high ridge bound- ing its ventral apical muscle scars. It is easily distin- guished from other similar forms in the Palmarito: none of the Marginiferidae bear a zygidium. In addi- tion, Echinauris bella Cooper and Grant (1975) is smaller, has more spines on the ventral valve, and bears dorsal spines as well, while Echinauris cf. E. lappacea Cooper and Grant (1975) bears on each dor- sal ear a thick brush of centripetally-directed thin spines. The smaller umbo of Echinauris cf. E. lium- bona Cooper and Grant (1975) in combination with other, less obvious characters, immediately distin- guishes it from A. sublaevis. Discussion.—As stated above, Anemonaria sublae- vis appears most closely related to Paucispinifera sul- cata. A slight suppression of the costellae of the latter would produce the appearance of the former. The Pal- marito form is assigned to A. sublaevis with the de- cided reservation that the classification system is, with regard to these forms, beginning to reveal its arbitrary nature to a great extent. There appears to be a contin- uous range of variation in radial ornament between A. sublaevis and P. sulcata, though, with a single excep- tion (in the Road Canyon Formation of West Texas), — they do not co-occur in a single bed in any region. It is hoped that future studies of specimens from single © localities, showing a more complete range of infra- population variation of these rare forms, will aid in clarification of their relationships. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 10 4 4 25 fine silicification Anemonaria? cf. A. sublaevis (R. E. King) Plate 5, figure 28 cf. Anemonaria sublaevis (R. E. King) Cooper and Grant, 1975, p. 1103, pl. 408, figs. 1-26. Types.—Figured Specimen: USNM 221221. Discussion.—Four fragmentary specimens from lo- cality 11 and one ventral valve from locality 1 exhibit © the characteristically subdued costellate exterior of - Anemonaria sublaevis (R. E. King) and are of the — proper size, shape and spine arrangement to warrant such specific assignment. No complete dorsal valve — has been recovered, however, in the absence of which — the presence or absence of a zygidium cannot be as- certained. Hence these specimens are only question- ably assigned to the genus and species. Material.— | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 69 Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 1 — — 11 3 — 1 calcite permineralization internal casts, with considerable adherent silicified ventral valve shell material Genus PAUCISPINIFERA Muir-Wood and Cooper, 1960 Type Species.—Paucispinifera auriculata Muir- Wood and Cooper, 1960, p. 320, pl. 122, figs. 1-16. Diagnosis.—Usually transversely rectangular, zy- gidium-bearing shells with poorly developed radial or- namentation. Occurrence.—Paucispinifera is known from the West Texas area, in formations ranging in age from Late Wolfcampian (Bone Spring Fm.) to Late Gua- dalupian (Bell Canyon Fm.). A large species occurs in the Guadalupian (Waagenoceras zone) of Las Deli- cias, Coahuila, Mexico. In the Palmarito fauna it has been recovered only from locality 8. Comparison.—Paucispinifera is distinguished from all genera outside the Paucispiniferidae by its having a zygidium in the dorsal valve. Of the Paucispiniferi- dae it is in general most closely related to Liosotella Cooper (in Cooper et al., 1953), though certain species of Paucispinifera may bear closer resem- blance to other paucispiniferids. Liosotella is com- monly strongly costate on both trail and visceral disc, Whereas Paucispinifera commonly is variably orna- mented longitudinally along the shell surface. Discussion.—Within the Paucispiniferidae, Ane- monaria Cooper and Grant (1969), Liosotella and Paucispinifera appear to constitute a plexus of forms which exhibit an almost continuous range of variation in radial ornament. Future studies of large samples of these forms are likely to reveal even more extensive intergradation than is now evident. Two Palmarito forms, Paucispinifera? cf. P. sulcata Cooper and Grant (1975) and Anemonaria sublaevis (R. E. King, 1931) are here considered similar at the conspecific or subspecific level, a relationship which their present generic assignments do not indicate. The number of specimens available for comparison in the Palmarito | fauna, however, is insufficient to warrant placement of Anemonaria in synonymy. Paucispinifera? cf. P. suleata Cooper and Grant Plate 5, figures 29-32 cf. Paucispinifera sulcata Cooper and Grant, 1975, p. 1137, pl. 418, figs. 1-51; pl. 475, figs. 21, 22. Description.—Medium-sized, small for genus, hav- ing transverse rectangular to subpentagonal outline and prominent triangular ears; widest at hinge. Umbo small, low; posterior and anterior slopes steep; great- est height at midvalve. Surface ornament of closely spaced costellae (commonly six in 5 mm at midvalve). Costellae weak on umbo, stronger anteriorly. Ventral valve deeply convex, delthyrium obsolete. Ears flat, slightly concave; separated from visceral slopes by single row of halteroid spines. Additional halteroid spines sparsely distributed over anterior and lateral slopes. Spines very rare along hinge and on ears. Entire surface bearing closely spaced costellae; costellae increasing anteriorly by intercalation. Oc- casional stronger costellae arising abruptly at halteroid spine bases, continuing anteriorly to margin. Commis- sure straight in anterior aspect. Anterior margin dis- tinctly sulcate; sulcus broad, commonly V-shaped, arising close to umbo and continuing to commissure. Dorsal valve concave; greatest depth anterior to midvalve. Surface faintly costellate, costellae stronger anteriorly, spaced as on opposite valve. Ears large, triangular, set at obtuse angle to umbonal slopes. Small triangular spine surmounting apparent zygid- ium. Margin anteromesially indented, producing low broad fold anteriorly only. Ventral interior unknown. Dorsal interior having small trilobate cardinal pro- cess with short shaft. Elongate triangular muscle scars flanking slender breviseptum; breviseptum terminating at midvalve. Row of small endospines anterior to end of breviseptum, extending across valve. Brachial ridges given off horizontally, lightly impressed. Measurements (in mm).— Dorsal Valve Hinge Mid- Length Length Width Width Height LOCALITY 8 USNM 221222 7/3} 15.2 20.0, SESS 10.3, USNM 221223 17.9 1335 29.40, 20.4 11.3 USNM 221224 18.3 h. 15.656 25.26, D226 10.2 Occurrence.—Paucispinifera sulcata, in the West Texas region where it was defined, occurs only in the Road Canyon Formation (Leonardian). The form here questionably assigned to the species has been re- covered in the Palmarito fauna from locality 8 where it is rare. A Leonardian age for this locality in the Palmarito is not inconsistent with other biostratigraph- ic indicators. Diagnosis.—Small Paucispinifera? with numerous costellae and a wide deep sulcus. 70 BULLETIN 313 Types.—Figured Specimens: USNM 221222-221223; Measured Specimens: USNM 221222-221224. Comparison.—Apparent mature individuals of P. auriculata Muir-Wood and Cooper (1960), P. inter- media Cooper and Grant (1975), P. rara Cooper and Grant (1975) and P. tumida Cooper and Grant (1975) are larger in size than are similar ontogenetic stages of P. sulcata, while ‘‘mature’’ specimens of P. inden- tata (Girty, 1909) are smaller. P. costellata Cooper and Grant (1975), which has radial ornament of the same scale and form as P. sulcata, bears a distinctive shelf surrounding the muscle attachment scars of the ventral apex. P. latidorsata (Girty, 1909), P. quadrata Cooper and Grant (1975), P. spinosa Cooper and Grant (1975) and P. suspecta Cooper and Grant (1975) have coarser radial ornament. P. transversa Cooper and Grant (1975) is far more transverse in outline. P. rectangulata Cooper and Grant (1975) is more square in outline, and more geniculate in lateral aspect. P. magnispina Cooper and Grant (1975) bears much larg- er halteroid spines. P. parasulcata Cooper and Grant (1975) has a very small ventral umbo, which projects little beyond the hingeline. Anemonaria sublaevis (R. E. King, 1931) is very similar to P. sulcata, yet may be distinguished by its less well-defined radial orna- ment. The presence of a zygidium in the dorsal valve effectively distinguishes P.? sulcata from other Pal- marito productaceans, except Anemonaria sublaevis. Discussion.—see discussion of Anemonaria sublae- vis. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 8 4 = — internal casts [dorsal valves]; medium-grained silicification [ventral valves] Family LINOPRODUCTIDAE Stehli, 1954 Subfamily LINOPRODUCTINAE Stehli, 1954 Genus HOLOTRICHARINA Cooper and Grant, 1975 Type Species.—Holotricharina hirsuta Cooper and Grant, 1975, p. 1175, pl. 444, figs. 1-49; pl. 445, figs. 9-15; pl. 446, figs. 42-45. Diagnosis .— Linoproductidae related to Grandaurispina but having two sizes of spines on the pedicle valve, non-costellate pedicle valve, but a capillate brachial valve. (Cooper and Grant, 1975, p. 1175) Occurrence.—Holotricharina occurs in the Cathe- dral Mountain and Road Canyon Formations (Leo- nardian) of the West Texas area. In the Palmarito For- mation it has been recovered from localities 4, 8 and 13. A Leonardian age for these localities is not incon- sistent with biostratigraphic evidence from other fau- nal elements in the Palmarito. Comparison.—Holotricharina may be distinguished from most Overtoniidae by its distinctively linopro- ductid cardinal process, and by the presence of fine capillae on the dorsal valve. The linoproductid Grand- aurispina Muir-Wood and Cooper (1960) has a more regular spine arrangement, and lacks the dorsal radial ornament of Holotricharina. Both Holotricharina and Grandaurispina have laterally directed clusters of hal- teroid spines arising below the ventral ears, but those of Grandaurispina are distinctly coarser than the larg- er body spines, whereas those of Holotricharina are of about the same size. Holotricharina may be distin- guished from all Linoproductidae except Grandauri- spina by the presence of two distinct kinds of spines, and by the absence of any radial ornament on the ven- tral valve. The regularity of spine arrangement sets apart the overtoniid Krotovia Frederiks (1928), as well as the Asian Permian overtoniids Comuquia Grant (1976) and Stictozoster Grant (1976). The Asian Perm- ian genus Dyschrestia Grant (1976) is externally prob- ably closest to Holotricharina, but its less transverse outline, a cardinal process of more marginiferid than linoproductid aspect and the lack of a dorsal brevisep- tum clearly distinguish it from Holotricharina. Discussion.—The two characters diagnostic of the genus, dorsal radial capillae and a linoproductid car-— dinal process are present only in the dorsal valve. There is only a single fragmentary, apparently imma- ture dorsal valve in the entire Palmarito suite of Holo- tricharina. Nevertheless, the presence of two kinds of ornament spines, as well as their irregular distribution suggests assignment of the Venezuelan forms to the genus Holotricharina. Holotricharina hirsuta Cooper and Grant Plate 5, figures 33-42 Holotricharina hirsuta Cooper and Grant, 1975, p. 1175, pl. 444, — figs. 1-49; pl. 445, figs. 9-15; pl. 446, figs. 42-45. Description.—Medium-sized, average for genus, concavo-convex thin shells; outline transversely sub- | rectangular to subtrigonal, interrupted by ears. Sides | nearly straight to gently rounded in anterior aspect; | anterior slope broadly rounded in lateral aspect. An- terior commissure unfolded. Hinge narrower than | | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 7\ midwidth; ears small, set at slight angle to body of shell. Dense cluster of slender halteroid spines along hinge, on and below ventral ears. Hinge spines di- rected posteriorly and posteroventrally, others direct- ed posterodorsolaterally, groups of spines commonly crossing near ears. Additional suberect, anterodorsal- ly directed halteroid spines scattered on anterior and ventrolateral slopes. Finer anteriorly directed recum- bent ornament spines on slopes and flanks of ventral valve. Ventral valve strongly and evenly convex in lateral profile, flat-topped and steep-sided in anterior profile. Beak small, pointed, umbo terminating above hinge- line; umbo moderately swollen posteriorly, protruding back beyond hingeline. Sulcus rarely developed. Dorsal valve moderately to deeply concave; greatest depth at or anterior to midvalve; steeper anteriorly than laterally. Ears only slightly set off from body of valve. Surface ornament of closely spaced concentric rugae; rugae weak mesially and anteriorly, very strong laterally and posterolaterally. Spines not observed; surface otherwise apparently smooth. Ventral interior having large, subcircular, paired diductor scars developed subapically, bearing rela- tively widely spaced narrow radial ridges. Surface oth- erwise smooth. Dorsal interior having small, slender bilobate car- dinal process with minute median lobe, only slightly deflected dorsally, and small shallow alveolus. Muscle scars paired, apparently elongate suboval, separated by slender breviseptum; breviseptum extending to midvalve. Anterior half of valve finely endospinose. Measurements (in mm).— Dorsal Total Valve Hinge Mid- Length Length Width Width Height Loca.iry 4 USNM 221225 = 12.7 11.3 10.8 16.7 pe 6.4 USNM 221226 14.8 12.3 11.0 Wi 2be 8.2 USNM 221227 16. Sn 14.1). 19:25. 21-dre 10.3 p56 USNM 221228 16.7 1S alive 19.2.4 2125) Wil USNM 221229 17.7, 14. le 24.8.1, 26.6cn 10.7p. Loca.ity 8 USNM 221230 14.5 11.2 13.2b¢ 18.2 7.8 USNM 221231 16.0, 12.4, 14.0), 20.8), 9.8 _ Occurrence.—Holotricharina hirsuta is known from the Cathedral Mountain and Road Canyon Formations of the West Texas region. This species was recovered in the Palmarito Formation at localities 4 and 8. A Leonardian age for these localities is not inconsistent with the other faunal evidence available. Diagnosis.—Medium-sized Holotricharina, some- what transverse in outline, with numerous spines on the body. Types.—Figured Specimens: USNM 221225, USNM 21227, USNM 221228, USNM 221230, USNM 21232; Measured Specimens: USNM 221225-221231. Comparison.—Holotricharina hirsuta is one of three known species of the genus, all originally de- scribed from the West Texas area. It is distinguished from H. sparsa Cooper and Grant (1975) by the lesser numbers of spines on that form, and from H.? sp. 1 of Cooper and Grant (1975), by its smaller size. The Palmarito specimens assigned to H. hirsuta are some- what larger than most of the West Texas individuals, but are here considered to be within the range of vari- ation in size of the species. In addition, the Venezue- lan examples are commonly more transverse than are their West Texas counterparts. This in itself might seem a basis for separation of the Palmarito specimens as a separate species, but it is considered that a larger suite of Venezuelan specimens should be studied be- fore such distinctions are attempted. A second Venezuelan form, Holotricharina? sp. A, is much larger than H. hirsuta. Its relationship to H.? sp. 1 is uncertain, however, since only a single rela- tively complete specimen of each is known. Discussion.—Only a single fragmentary dorsal valve of H. hirsuta was recovered in the present collections. Small in size, the undifferentiated cardinal process and presence of a shallow submyophoral alveolus indicate it to be that of an immature individual. In all other characters, however, the Palmarito specimens can be assigned confidently to H. hirsuta. 2) 2 Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 4 4 — 4 fine silicification 8 3 1 = fine silicification; internal cast of a single dorsal valve Holotricharina? sp. A Plate 5, figures 43-45 Description.—Medium-sized, large for genus, thin, convex ventral valve; in general form, outline and spine arrangement as in H. hirsuta, except umbo greatly swollen, produced further posterior to hinge- line. Ventral interior having slight ginglymus developed mesially; surface otherwise smooth. 72 BULLETIN 313 Measurements (in mm).— Dorsal Total Valve Hinge Mid- Length Length Width Width Height Loca.ity 13 USNM 221233 26.5 16.4, 13.2 25.1 16.2bce Occurrence.—Holotricharina? sp. A is known from a single ventral valve recovered from locality 13. The age of the assemblage at that locality, based on other faunal evidence is latest Leonardian to Early Guada- lupian. Diagnosis.—Large Holotricharina? with swollen, posteriorly produced umbo and two sizes of spines. Types.—Figured and Measured Specimen: USNM 221233. Comparison.—Only Holotricharina? sp. 1 Cooper and Grant (1975) is of sufficiently large size to be con- fused with H.? sp. A. It may be distinguished by the presence of three distinct sizes of spines on the ventral valve, as contrasted to the two sizes seen in H.? sp. A. It may be that these two species are related more closely than their designations would indicate. The difference in type of spinose development would ap- pear, however, to make this unlikely. Discussion.—More formal designation of a species name for this form should await study of additional specimens of both it and related forms. Although frag- ments of ventral valve apparently belonging to this form were recovered at several localities, no recog- nizable piece of dorsal valve was found. In the absence of this, an unequivocal generic assignment cannot be made. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 8 — — fine silicification fine silicification 1 = Me 13 = = fine silicification 1 10 — —_— 1 1 fine silicification Family RETARIIDAE Muir-Wood and Cooper, 1960 Genus KUTORGINELLA Ivanova, 1951 Type Species.—Kutorginella mosquensis E. A. Iva- nova, 1951, p. 329. Occurrence.—Kutorginella is known from latest Mississippian and Pennsylvanian and Permian strata. In the Mississippian it has been recognized only in Europe, while in the Pennsylvanian it is reported from both Europe and the North American midcontinent. In the Permian its range extends to include the South American continent as well (Samtleben, 1971). Comparison.—Kutorginella may be distinguished from Tubaria Muir-Wood and Cooper (1960) by the wider hinge and distinctive long tubiform trail of that genus; from Thamnosia Cooper and Grant (1969) by the greater number of spines on species of that genus, these especially concentrated on the anterior portions of the trail and on the ears. Discussion.—Antiquatonia Miloradovich (1945) is externally quite similar to Kutorginella: indeed, they differ only in the tubiform trail that may form a diag- nostic character in the latter genus, but which all too often is not preserved. Internally, however, the short- er dorsal lateral ridges and the massive, sessile car- dinal process clearly distinguish Antiquatonia. Vari- ation in these very internal characters, however, in the Venezuelan specimens, indicates the close rela- tionship existing between the two genera, notwith- standing their classification in two distinct families. — Indeed, Sarytcheva (1971, p. 452) suggests that Ku- torginella was derived in Early Pennsylvanian time from an Antiquatonia-like ancestor, if not Antiqua- tonia itself. Kutorginella cf. K. umbonata (Muir-Wood and Cooper) Plate 6, figures 1-10 cf. Retaria umbonata Muir-Wood and Cooper, 1960, p. 231, pl. 70, figs. 1-15. ef. Kutorginella umbonata (Muir-Wood and Cooper) Cooper and Grant, 1975, p. 1030, pl. 343, figs. 18-33; pl. 344, figs. 1-30. Description.—Medium-sized, average for genus, subplanoconvex to concavo-convex thin shells with large body cavity; subtrigonal in outline; hinge equal to or slightly less than midwidth; distinctly bilobate in anterior aspect, with gently rounded flanks and dis- tinct ventral sulcus; broadly domed in lateral aspect, having steep anterior and posterior slopes. Both valves geniculate. Umbonal regions strongly reticu- late; anterior regions distinctly costellate. Valves_ sparsely spinose. Ventral valve having low umbo, produced a small’ distance beyond hingeline. Ears thin, triangular, pla- nar to somewhat convex exteriorly, set at acute angle’ to body. Umbo finely reticulate, having rugae stronger | than costellae; rugae increasing in strength laterally to’ bases of ears, diminishing in strength anteriorly, ob- | solescent at margin of visceral disc. Costellae fine,’ commonly seven to eight in a 5 mm distance at mid-| PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 15 valve; rarely increasing anteriorly by splitting or in- tercalation. Spines in single row roughly following hinge; in more distinct row up flanks, not on spine ridge, definitely mesial to break in slope between body and ears; scattered over flanks, sulcus and trail, in- creasing in size anteriorly; arising from crests of cos- tellae. Distinct sulcus arising just anterior to umbo, continuing to anterior commissure. Delthyrium tiny, nearly obsolete. Dorsal valve without spines, having planar to slight- ly concave visceral disc margin. Low obscure fold de- veloped on visceral disc, becoming more distinct on trail, continuing to anterior commissure. Visceral disc finely, strongly reticulate; trail evenly, finely costel- late. Tiny pointed lophidium closing ventral delthyri- um. Ventral interior having low, wide ginglymus extend- ing laterally onto ears. Submarginal ridges non-cren- ulate, arising in umbo and continuing across bases of ears as ear baffles; not internally striate. Umbonal apex having sharp median ridge, separating paired, striate, anteriorly expanded, rounded triangular diduc- tor scars; median ridge succeeded anteriorly by raised callus platform bearing paired elongate dendritic ad- ductor scars. Diductors large, extending anterior of ends of adductors. Remainder of surface broadly re- flecting exterior ornament. Dorsal interior having variable cardinal process, with or without short shaft; commonly trilobed, with expanded median lobe, lobe dorsally deflected and mesially sulcate. Strong lateral ridges running along hingeline and across bases of ears as ear baffles; ridges sharply crested, but not crenulate or internally striate. Broad base of cardinal process narrowing anteriorly to form slender breviseptum; breviseptum continuing to visceral disc margin, posteriorly separating poste- riorly broad, elongate oval, dendritic adductor scars, scars raised on callus platforms. Reniform, mesially concave, lightly impressed, finely pitted areas poste- rior and lateral to adductors. Remainder of surface reflecting exterior ornament. Measurements (in mm).— Hinge Mid- Length Width Width Height Material LocaLity 4 USNM 221234 19.1). 30.06, 11.4, (dorsal valve) USNM 221235 22. Spe — 30.0. 16.3 (articulated valves) LocaLirty 8 USNM 221236 18.8 31.0), 6.3 (dorsal valve) USNM 221237 23.0 — 13.8, (articulated valves) Occurrence.—Kutorginella umbonata has been re- covered, in the West Texas region where it was first described, from the Cathedral Mountain and Road Canyon Formations. In the Palmarito the form here referred to the species appears at localities 1, 4, 7, 8 and 11. It is not abundant at any of these localities, but is commonest at localities 4 and 8. The Leonardian age of the West Texas forms is not inconsistent with biostratigraphic evidence available as a guide to the age of the Palmarito beds in which the related form occurs. Diagnosis.—Large Kutorginella with anterior mar- gin thrown into a broad plication. | Types.—Figured Specimens: USNM 221234—-221239; |Measured Specimens: USNM 221234—-221237. Comparison.—Kutorginella umbonata may be dis- tinguished from K. robusta Cooper and Grant (1975) by the larger size and more subtle sulcation of the latter form; from K. sullivanensis (R. E. King, 1931) by the distinctive spine distribution of that form; from K. uddeni Cooper and Grant (1975) by the smaller lateral spines of that form and its less well-defined ventral sulcus. K. lasallensis (Worthen in Meek and Worthen, 1873) is somewhat more strongly costellate and has stronger, more numerous body spines; K. par- vispinosa (Stehli, 1954) is a very similar form, but it is not so distinctly sulcate ventrally. K. swbquadrata (Cooper in Cooper et al., 1953) and K. occidentalis (Cooper in Cooper et al., 1953) also lack this distinct character. K. meridionalis (McKee, 1938) also is less sulcate and has coarser costellation. Discussion.—None of the Palmarito specimens shows the distinctive trail development that is char- acteristic of the Retariinae. No dorsal valve is pre- served in its entirety, but the various pieces recovered allow the formulation of a composite description. The distinct deep ventral sulcus of the Palmarito form sets it apart from most other species of the genus, except K. umbonata. It does not appear to have as great a development of the anterior marginal ring of dorsal endospines as is common in K. umbonata in West Texas. The distinctive row of spines across the flanks, above the ventral ears, and across the anterior margin is clearly seen only on a single Palmarito specimen, 74 BULLETIN 313 from locality 1. This specimen is unfortunately se- verely crushed, and none but exterior details can be discerned. For the above reasons, in addition to the comparative rarity of the form in the Palmarito For- mation, no definite species assignment can be made. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation : : 7" o calcite permineralization = a fine silicification; some internal casts 7 = se | calcite permineralization 8 6 7 10 fine silicification; some internal casts 11 2 1 3 medium-grained silicification Family ECHINOCONCHIDAE Stehli, 1954 ECHINOCONCHIDAE genus indeterminate Plate 5, figure 46 Types.—Figured and Measured Specimen: USNM 221240. Discussion.—A single specimen, comprised of the partial interior of a dorsal valve and the adjacent apical portion of the ventral valve of an unsilicified, apparent echinoconchid brachiopod was recovered from an ho- rizon high in the Palmarito Formation. It was not col- lected during the present study, but forms part of the Arnold Collection, now housed in the collections of the National Museum of Natural History in Washing- ton, D.C. This collection was assembled in the course of a chiefly stratigraphically-oriented study under- taken by H. C. Arnold in 1960 and later formally re- ported (Arnold, 1966). The specimen, designated as Ar. 981-R, was identified for that publication as ““? Bathymyonia cf. nevadensis (Meek),’’ by Helen M. Muir-Wood. It has not, however, been formally de- scribed. The myophore and shaft of the cardinal process have unfortunately been lost. Some diagnostic fea- tures, however, remain in the dorsal interior. The thin lateral ridges diverge slightly from the hingeline. The muscle attachment area appears small and poorly im- pressed. A thin median septum, flanked on either side by a broader, low submedian ridge, extends to about midvalve. Endospines, arranged in distinct concentric rows beyond the septum, are assumed to reflect an exterior ornament of concentric bands. The valve it- self is only slightly concave and appears somewhat geniculate anteriorly. The ventral umbo appears to extend considerably beyond the hinge. The flattened dorsal valve, protruding ventral umbo, obscure brachial ridges and most of all the apparent concentrically banded ornament indicate proper as- signment of this productacean to the Echinoconchi- dae. Measurements (in mm).— Dorsal Total Valve Hinge Maximum Length Length Width Width USNM 221240 37.4. SES: 29.6, 32:68 (Arnold Coll. Field No. Ar. 981-R) Family DICTYOCLOSTIDAE Stehli, 1954 Subfamily DICTYOCLOSTINAE Stehli, 1954 Genus PENICULAURIS Muir-Wood and Cooper, 1960 Type Species.—Peniculauris mckeei Muir-Wood and Cooper, 1960, p. 280, pl. 100, figs. 1-7; pl. 101, figs. 1-3 = Aulosteges subcostatus R. E. King, 1931, p. 94, pl. 25, figs. 5-7. Diagnosis.—Large semireticulate dictyoclostids having an irregularly semireticulate visceral disc re- gion, numerous small body spines on the visceral disc and trail, and a brush of fairly slender but long halter- oid spines on the ears. Numerous spines on the dorsal valve. Cardinal process commonly large, spreading, strongly trilobed. Occurrence.—Peniculauris occurs in the West Tex- as region in beds of from Late Wolfcampian (Skinner Ranch Formation) to Late Leonardian (Road Canyon Formation) age. It appears in the Chochal Limestone (Leonardian) of Guatemala (Stehli and Grant, 1970), identified as Kochiproductus? sp. (p. 32, pl. 11, fig. 11; pl. 13, figs. 1-7) and as Peniculauris mckeei Muit- Wood and Cooper (1960) (Stehli and Grant, 1970, p. 32, pl. 11, figs. 7-10). In the Palmarito fauna it has been recovered from localities 1 and 5. A Late Wolf- campian to Late Leonardian age is consistent with other biostratigraphic indicators for these localities. Comparison.—Peniculauris closely resembles Kochiproductus Dunbar (1955) externally, but may be PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 75 distinguished from that genus by its lack of an antron in the base of the dorsal breviseptum, a diagnostic feature of that buxtontid genus. Peniculauris some- what resembles Squamaria Muir-Wood and Cooper (1960), but lacks the auricular cluster of dorsal spines diagnostic of that genus. Dasysaria Cooper and Grant (1969), although similar in exterior ornament, lacks the dorsal spines characteristic of Peniculauris. Peniculauris subcostata latinamericana new subspecies Plate 6, figures 11-20 Peniculauris mckeei Muir-Wood and Cooper, Stehli and Grant, 1970, p. 32, pl. 11, figs. 7-10. Kochiproductus? sp. Stehli and Grant, 1970, p. 32, pl. 11, fig. 11; pl. 13, figs. 1-7. Etymology of Name.—Engl. latin american + a. Description.—Large, small to average for genus, subrectangular to transverse in outline, concavo-con- vex shells; widest at hinge, moderately to highly domed in anterior aspect, with narrow sulcus and steeply sloping flanks; anterior and posterior slopes rounded in lateral aspect; geniculation pronounced. Ears small, triangular to rounded, concave. Both valves spinose, ventral valve considerably so. Ventral valve deeply convex, elongate to trans- verse; greatest height at venter; ovate to trapezoidal in outline, quite variable. Beak small, low, raised only slightly dorsal to hingeline; umbo comparatively small, projecting short distance posterior to hingeline. Or- nament of (1) concentric rugae, very strong along hinge, weaker mesially, weakening anteriorly and be- coming obsolete at venter, and (2) fine costellae, six to eight in a 10 mm distance posterior to venter, eight or more in a 10 mm distance on trail, becoming higher, wider, more prominent from umbo to venter; at venter abruptly splitting and thinning, becoming less promi- nent toward anterior margin; increasing anteriorly in each region by intercalation or splitting. Spines (1) in ray originating at beak, diverging slightly from hinge, spreading onto ears, there expressed as dense tuft of slender halteroid spines, (2) dispersed over surface of valve posterior to venter on locally raised intersec- tions of costellae and rugae, increasing in size from -umbo to venter, decreasing in size from venter ante- riorly, very fine on trail, staggered on alternating cos- tellae. Interspine portions of costellae distinctly lower, each spine concentrically adjacent to saddle between spines in next radial row. Trail repeatedly broken some distance anterior to venter, commonly exhibiting ten or more overlapping lamellar trails. Ears rounded or triangular, sides anterior to ears indented or not, quite variable. Distinct narrow sulcus, arising at umbo and continuing to anterior margin, somewhat obscured anteriorly by overlapping trails. Anterior commissure broadly rounded, slightly indented mesially. Dorsal valve concave, greatest depth at about mid- valve, surface finely costellate umbonally, more coarsely so anteriorly; finely rugose posteriorly, rugae becoming obsolete anteriorly. Both radial and concen- tric ornament less pronounced than on opposite valve. Maximum degree of reticulation at midvalve. Fine spines apparently present, rarely preserved, located on intersections of costellae and rugae, as on opposite valve. Ears gently rounded, concave; valve distinctly geniculate. Low broad fold, originating in umbonal hollow, broadening anteriorly, slightly indenting an- terior commissure. Ventral interior finely granulose, otherwise un- known. Dorsal interior having small, short-shafted, typically dictyoclostid cardinal process; trilobate, median lobe of myophore dorsally deflected, mesially sulcate, all lobes crenulate. Lateral ridges arising at base of car- dinal process, thinner and flatter laterally, diverging slightly from hinge, crossing bases of ears as distinct, somewhat raised, granulose to pustulose ridges, there expressed as low step in shell surface, step continuing around visceral disc. Broad base of cardinal process thinning anteriorly, replaced by narrow, bladelike breviseptum; breviseptum continuing beyond mid- valve, terminating in slightly raised, slightly broad- ened keel. Breviseptum flanked posteriorly by two pairs of adductor muscle scars. Anterior pair coarsely dendritic, elongate triangular, broadening anteriorly, terminating short of brachial ridges; posterior pair elongate triangular, coarsely dendritic, broadening an- teriorly, adjoining anterior pair posterolaterally, the two making a larger, more equilaterally triangular composite muscle scar. Both marks raised on low cal- lus platforms. Brachial ridges given off horizontally, narrowly looped anteriorly. Remainder of surface (1) irregularly pustulose posterior to brachial ridges, (2) smooth to obliquely broadly ridged within brachial ridge field, and (3) covered by low, conical, striate, anteriorly directed, prostrate endospines mesial, an- terior and anterolateral to brachial ridges. Endospines smaller anteriorly, raised on low ridges mirroring ex- ternal costellae. Exterior fold internally reflected as anteriorly broadening mesial furrow, containing brev- iseptum. 76 BULLETIN 313 Measurements (in mm).— Costae in Surface Hinge Mid- 10 mm on Length Length Width Width Height trail Locatity 1 USNM 221241 3939": 77 59.2, 46.3. 30.0, 9 USNM 221242 42.5 80 60.0), 50.4en 28.3, 8 USNM 221243 44.5. 76 71.6en Sean 26.2, 8 USNM 221244 47.0 82 52.6, 46.2 26.2 8 (holotype) USNM 221245 48.0 95 50.0, 45.1 833 9 Occurrence.—Peniculauris subcostata latinameri- cana n. ssp. is known at present only from Central and South America. Stehli and Grant (1970) reported it as P. mckeei Muir-Wood and Cooper (1960) and as Kochiproductus? sp., from the Chochal Limestone (Leonardian) of Guatemala. In the Palmarito fauna it has been recovered only from locality 1. A single set of extremely poorly preserved articulated valves, questionably referred to the subspecies, was re- covered from locality 5. Diagnosis. —Medium-sized, variably shaped Peni- culauris subcostata having fine costae; costae increas- ing dramatically in number anterior to venter. Types.—Holotype: USNM 221244; Figured Speci- mens: USNM 221242, USNM 221244-221248. Mea- sured Specimens: USNM 221241-221245. Comparison.—Peniculauris subcostata latinameri- cana n. ssp. is distinguished from P. bassi McKee (1938), P. costata Cooper and Grant (1975), P. imitata Cooper and Grant (1975) and P. subcostata subcos- tata (R. E. King, 1931) by the larger mean size of the costae in those forms; from P. peniculifera Cooper and Grant (1975) by the smaller size of the mature individuals of that species; from P. ivesi (Newberry, 1861) by the larger size and wider costae of that form; from P. transversa Cooper and Grant (1975) by the more transverse outline, larger ears, generally larger size and coarser costae of that form. Some of the West Texas specimens referred by Coo- per and Grant (1975) to P. subcostata (R. E. King, 1931) show the anterior proliferation of small costae peculiar to P. s. latinamericana, but not to the extent or degree exhibited by the majority of the Palmarito specimens. In addition the sample of the Venezuelan population shows a far greater degree of variation in form and outline than do the West Texas samples. Although there is some overlap in size between the two samples, it is readily apparent that the mean size of mature individuals is greater in the West Texas forms. Due to the extreme crushing suffered by most of the Venezuelan specimens, comparative measure- ments are not as impressive or consistent as they might be. P. s. latinamericana n. ssp. is easily distin- guished from other Palmarito Dictyoclostinae: from Spinifrons grandicosta n. sp. by the broader costae and large anteroventral halteroid spines of that form; from Rugatia intermedia n. sp. and R. occidentalis (Newberry, 1861) by the smaller size, coarser orna- ment and aspinose dorsal valve of those forms. Discussion.—Peniculauris subcostata, as clearly elucidated by Cooper and Grant (1975), is in a peculiar position. The type specimens, a holotype and three paratypes, all fragmental valves, were mistaken by R. E. King (1931) for Aulosteges, and were so considered until additional preparation by Cooper revealed their dictyoclostid affinities. The type specimens of Peni- culauris mckeei, now in synonymy with A. subcos- tatus, constitute a much larger, more representative suite, yet the rules of taxonomic procedure determine that comparisons should formally be made with the primary types, not synonymous forms. The assign- ment of the Venezuelan forms to P. subcostata latin- americana, however, is entirely on the basis of com- parisons made to Muir-Wood and Cooper’s now- ineligible types and topotypic material, rather than to King’s primary types. The Guatemalan specimens here referred to P. s. latinamericana represent extremes of the range of variation of the Palmarito representatives. The two specimens described (Stehli and Grant, 1970, p. 32) as Kochiproductus? sp. (USNM 163587 and USNM 163588) are of a large form compared to most Palma- rito specimens, with comparatively coarse costae, yet they show the anterior proliferation of costae well. The form and size of the larger specimen (USNM 163587) is similar to Palmarito specimen USNM 221243. The single shell (USNM 163575) described as Peniculauris mckeei (Stehli and Grant, 1970, p. 32) is more similar in size and form to a Palmarito specimen USNM 221245. In the presence of the Venezuelan material, it is not difficult to consider the Guatemalan specimens as individuals deriving from the same species population. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 77 Material.— Locality Articulated Dorsal Ventral Type of Preservation Valves Valves Valves 1 3 4 26 calcite permineralization 5 1 _ — coarse silicification Genus RUGATIA Muir-Wood and Cooper, 1960 Type Species.—Productus (Dictyoclostus) parain- dicus McKee, 1938, p. 241, pl. 46, figs. 5a—b. Diagnosis.—Crudely reticulate and irregularly cos- tate Dictyoclostidae, commonly with a cluster of large thick halteroid spines on the ears and a few scattered on the trail slope. Occurrence.—Rugatia has been recovered from Permian rocks in the Western United States, Central America and, with this report, South America. In the West Texas area where it has been most extensively studied, it has been recovered from the Neal Ranch, Skinner Ranch and Bone Spring Formations (Wolf- campian) and the Cathedral Mountain and Road Can- yon Formations (Leonardian). One species, R. occi- dentalis (Newberry, 1861) is known from the Kaibab Formation (Leonardian) of Arizona, and another, R. andersoni Stehli and Grant (1970) from the Chochal Limestone (Leonardian) of Guatemala. Two species, one of them new, are here reported from the Palmarito Formation of Venezuela. An Early Permian age for the localities in which these species were found is not inconsistent with other biostratigraphic indicators. Comparison.—Rugatia may be distinguished easily from Antiquatonia Miloradovich (1945), Spinarella Cooper and Grant (1975) and Dasysaria Cooper and Grant (1969) by the finer radial ornament of those forms; from Peniculauris, Spinifrons Stehli (1954) and Squamaria Muir-Wood and Cooper (1960) by the presence of dorsal spines in those genera; from Cos- tiferina Muir-Wood and Cooper (1960), Liosotella Cooper (in Cooper et al., 1953) and Antiquatonia, which also have a single row of halteroid spines arising at the ventral umbo, but in none of which does the row pass over the surface of the ears themselves, but rather follows the break in slope between ears and body; from Reticulatia Muir-Wood and Cooper (1960), Peniculauris Muir-Wood and Cooper (1960) and Stereochia Grant (1976) by the stronger reticula- tion of those forms; from Peniculauris, Reticulatia, Xestosia Cooper and Grant (1975) and Dasysaria by their having a thick brush of spines on the ears, al- though one species of Rugatia, R. paraindica (McKee 1938) does approach this condition. Nudauris Stehli (1954) has a distinctive ornament of mixed costellae and costae, not seen in Rugatia. Chaoiella Frederiks (1933), unlike Rugatia, bears very weak radial orna- ment. Discussion.—It is in one sense unfortunate that the type species of the genus Rugatia should be R. para- indica. In making this form representative of the ge- nus, it follows that a trait like the tuft of spines on the ventral ears will be taken as pervasive in, rather than indicative of the genus. In actuality however, most species of the genus do not share this trait, but rather have a single well-defined row of halteroid spines aris- ing on the ventral umbo and running out onto the ears. Rugatia intermedia new species Plate 6, figures 21-28 Etymology of Name.—L. intermedia = intermedi- ate. Description.—Medium to large, large for genus, concavo-convex transverse shells, trapezoidal in out- line, widest at hinge, Highly domed, steep-sided in anterior aspect; steeply sloping anteriorly and posteri- orly in lateral aspect; both valves strongly geniculate. Surface sparsely spinose. Umbonal regions and vis- ceral discs semi-reticulate, having rugae stronger than radial ornament; anterior and lateral regions strongly costate. Distinct ventral sulcus; subtle dorsal fold. Ventral valve deeply convex, having long acuminate concave ears set at sharp angle to body of shell. Single row of spines arising at umbo, increasing in size lat- erally and posteriorly, diverging from hinge at low an- gle; eight spines on each side of ventral umbo of spec- imen having hinge width = 46.4 mm. Additional very fine halteroid spines scattered on flanks and in sulcus; spines quite large near anterior margin. Costae in- creasing in size and strength anteriorly. Dorsal valve concave, geniculate; triangular con- cave ears set off from excavate visceral disc by low oblique ridge. Surface dimpled, semireticulate on vis- ceral disc, faintly rugose laterally and on ears; costae more evident anterolateral of visceral disc. Ventral interior having low, wide ginglymus and open delthyrium. Bases of ear spines open to interior below ginglymus. Narrow, elongate, dendritic adduc- tor muscle scars, posteriorly striate, on high platform; platform median in shell, narrowing anteriorly. Ad- ductors separating large, anteriorly expanded, striate 78 BULLETIN 313 diductor scars. Adductor platform extending to op- posite margin of dorsal visceral disc. Surface ante- riorly and laterally faintly granulose, bearing low fur- rows reflecting exterior ornament. Dorsal interior having typical sessile dictyoclostid cardinal process with broadly trilobate myophore; median lobe mesially sulcate. Spinelike lophidium, serving to close ventral delthyrium, produced dorsal- ly. Lateral ridges serving mesially as articulatory pro- cesses, following along hinge, becoming low, obsolete on ears. Broad base of cardinal process narrow ante- riorly, forming slender bladelike breviseptum; brevi- septum anteriorly raised, terminating at anterior mar- gin of visceral disc. Breviseptum flanked posteriorly by large elongate triangular dendritic adductor scars, set on callus platforms. Brachial ridges given off hor- izontally, faintly impressed. Remainder of surface semireticulate, rugose or costate, mirroring external ornament. Measurements (in mm).— Surface Hinge Mid- Thick- Length Length Width Width Height ness Loca.ity 10 USNM 221249 26.3 50. 46.4 32.6 21.6 12.0, (holotype) Occurrence.—Rugatia intermedia occurs in the Pal- marito Formation at localities 4, 8, 10 and 11. It isa rare element at localities 4, 10 and 11, but common at 8. Similar forms, R. mckeei Cooper and Grant (1975) of the West Texas region and R. andersoni Stehli and Grant (1970) from the Chochal Limestone of Guate- mala, are of Leonardian age. A Leonardian age for the above localities is not inconsistent with other bio- stratigraphic indicators. Diagnosis.—Strongly costate, transverse Rugatia with a single row of spines on the ventral ears and distinctly reticulate visceral disc regions. Types.—Holotype: USNM 221249; Figured Speci- mens: USNM 221249-221252; Measured Specimen: USNM 221249. Comparison.—Rugatia intermedia is easily distin- guished from R. incurvata (R. E. King, 1931) by its larger adult size, and from R. paraindica (McKee, 1938) by the larger size and greater number of ear spines of that form. It is more transverse in outline and somewhat larger than R. convexa Cooper and Grant (1975), and both larger and more strongly or- namented than the other Palmarito species, R. occi- dentalis (Newberry, 1861). It is probably most closely related to R. mckeei, which is larger, has fewer spines on the ears, and bears slightly less marked reticulation on the umbonal regions, and to R. andersoni, which is slightly smaller, less transverse, and bears weaker costae that are less closely packed than on R. inter- media. It is easily distinguished from other Palmarito Dictyoclostinae: from Peniculauris subcostata latin- americana n. ssp. by the larger size, more distinct ornament and greater spine density of that form; from Spinifrons grandicosta n. sp. by the dorsal fine and anteroventral coarse spines of that form. Discussion.—R. andersoni, R. intermedia and R. mckeei evidently form a plexus within which specific distinctions are cloudy. Since the gradation is chiefly in shape and form, and because the Palmarito speci- mens are largely fragmented, no ‘‘quantitative’’ esti- mate of comparative similarity of R. intermedia to one of the other two species is here attempted. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 4 1 l = fine silicification; some casts 8 5 3 25 fine to medium silicification; some casts 10 1 — — fine silicification 11 1 1 3 fine silicification Rugatia occidentalis (Newberry) Plate 6, figures 29-35 Productus costatus Marcou (non Sowerby, 1827), 1858, p. 46, pl. 351i ok Productus occidentalis Newberry, in Ives, 1861, p. 122, pl. 2, figs. 9, 10; R. E. King, 1931, p. 72, pl. 14, figs. 11, 12, 14 (non fig. 13 = Rugatia paraindica McKee, 1938, p. 239, pl. 46, figs. 1-4). Productus (Dictyoclostus) meridionalis McKee in Stoyanov, 1936, p. 523. Rugatia occidentalis (Newberry), Cooper and Grant, 1975, p. 1082, pl. 378, figs. 9-13. non Productus occidentalis Newberry, Girty, 1909, p. 262, pl. 12, figs. 4a—c [=Liosotella Cooper (in Cooper et al., 1953)]. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 719 Description.—Medium to large, average-sized for genus, concavo-convex shells, subquadrate to elon- gate rectangular in outline. Hinge width variable; slightly less than to slightly more than midwidth. Steep-sided, flat-bottomed, subrectangular in anterior aspect; spiral, somewhat geniculate in lateral aspect, having steep posterior slope and gently rounded an- terior slope. Surface sparsely spinose. Umbonal re- gions having faint concentric lirae and faint reticula- tion; anterior regions broadly costate; costae low, obsolescent. Variable ventral sulcus developed. Com- missure straight in anterior aspect, gently rounded in dorsal aspect. Delthyrium obsolete; low ginglymus present. Ventral valve deep, having small, compact, distinct- ly concave ears. Single row of spines arising at umbo, increasing in size laterally and posteriorly, diverging from hinge at low angle; 11 spines on each side of beak on specimen with hinge width = 39.0 mm. Additional slender halteroid spines arising on crests of obsoles- cent costae, scattered on slopes and in sulcus, becom- ing more robust anteriorly. Costae arising and dying out anteriorly by intercalation. Dorsal valve gently concave, with small concave ears, valve very sparsely spinose, spines rarely pre- served. Ornament of faint concentric lirae. Ventral interior faintly granulose near anterior and lateral margins, otherwise not observed. Dorsal interior having typical sessile dictyoclostid cardinal process; trilobed myophore, with large, dor- sally reflexed, mesially sulcate median lobe. All lobes corrugate. Lateral ridges short, low, dying out mesial to ears. Basal boss of cardinal process merging ante- riorly into long slender breviseptum; breviseptum ter- minating at anterior end of visceral disc. Anterior ad- ductor scars elongate, dendritic, diverging anteriorly from breviseptum; dendritic posterior adductor scars reniform, concave mesially, located posterolateral of anterior adductors. Both sets of scars set on slightly raised callus platforms. Anterior and lateral portions of valve not seen. Measurements (in mm).— Hinge Mid- Length Width Width Height Loca.ity 1 USNM 221253 DES 39.0cn 20.86 17.8, USNM 221254 25.0, 30.0, 27.6, 15.0, USNM 221255 28.3, 3PM 30.0, 16.5, USNM 221256 32.8, 34.0cn 30.0, 19.7, Occurrence.—R. E. King (1931) reported R. occi- dentalis from various localities in the West Texas area, in beds ranging in age from Late Wolfcampian to Early Guadalupian. A subspecies, R. occidentalis parvauris Cooper and Grant (1975), came from the Cathedral Mountain Formation (Leonardian) in the same area. Newberry (1861) collected the type Productus occi- dentalis from the Kaibab Formation of the Grand Can- yon region, Arizona, the age of which is Late Leo- nardian. In the Palmarito Formation this form has been recovered only from locality 1, for which an Ear- ly Permian age is not inconsistent with other biostrati- graphic indicators. Diagnosis.—Elongate rectangular, steep-sided Ru- gatia, with small concave ears and subdued ornament. Types.—Figured Specimens: USNM 221253, USNM 221254, USNM 221256, USNM 221257; Measured Specimens: USNM 221253-221256. Comparison.—On the average, mature specimens of Rugatia occidentalis are larger than similar onto- genetic stages of R. incurvata (R. E. King, 1931), and smaller than like stages of R. andersoni Stehli and Grant (1970), R. mckeei Cooper and Grant (1975) or R. paraindica (McKee, 1938). A similar form, R. con- vexa Cooper and Grant (1975), is more tightly spiralled than R. occidentalis. Although some of the Palmarito specimens have the very small ears and short hinge of R. occidentalis parvauris, these appear in the Vene- zuelan specimens to intergrade with more typical R. occidentalis, so that assignment to that subspecies is not there justified. R. occidentalis may be distin- guished from the other Palmarito species of the genus, R. intermedia n. sp., by its smaller size, less promi- nent, smaller ears, and the less pronounced reticula- tion of the visceral disc regions of both valves. It may as easily be distinguished from other Palmarito Dic- tyoclostinae: from Peniculauris subcostata latinamer- icana n. ssp. by the larger size, more distinct ornament and greater spine density of that form; from Spinifrons grandicosta n. sp. by the presence of dorsal fine and anteroventral coarse spines in that form. Discussion.—The range of variation of topotypic specimens of R. occidentalis is not well-known. Be- cause the Palmarito material is scanty and not well- defined stratigraphically, it is better to assign the form to an existing if incompletely understood species, than to erect another incompletely known species in order to justify real or imagined differences between the two. The Palmarito specimens were all recovered from a limy shale, and in the process of compaction of that rock had been extensively crushed. They were not silicified and were removed mechanically from the en- closing matrix. Thus it is difficult to ascertain the orig- inal form of the shell with certainty. 80 BULLETIN 313 Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 1 1 32 calcite permineralization 7 — = 1? calcite permineralization Genus SPINIFRONS Stehli, 1954 Type Species.—Spinifrons quadratus Stehli, 1954, p. 318, pl. 20, figs. 6-10. Diagnosis.—Large Dictyoclostidae with a tuft of large spines on the ears, large halteroid spines on the anterior median part of the trail and slender hair-like spines on the dorsal valve. Occurrence.—Spinifrons is known from the Penn- sylvania and Permian of the United States, though only a single species of Pennsylvanian age is referred to the genus (Stehli, 1954, p. 318). In the West Texas region it appears to be largely limited to Late Wolf- campian strata, although specimens questionably re- ferred to Spinifrons spp. have been recovered from strata as young as Guadalupian. Other biostratigraphic indicators in the Palmarito Formation suggest that the age of the Venezuelan representatives of the genus lies in the Leonardian, if not Guadalupian. Comparison.—Spinifrons is easily distinguished from other genera within the Dictyoclostinae: from Antiquatonia Miloradovich (1945), Spinarella Cooper and Grant (1975) and Dasysaria Cooper and Grant (1969) by the finer radial ornament of those genera; from Squamaria Muir-Wood and Cooper (1960) by the presence of a brush of dorsal ear spines in that genus; from Reticulatia Muir-Wood and Cooper (1960) and Rugatia Muir-Wood and Cooper (1960) by the absence of dorsal spines of any form in those genera; from all others by the presence of large halteroid spines, not only in a dense brush on the ears, but also in a con- spicuous group anteromesially on the ventral sulcus and near the ventral anterior margin. Discussion.—Spinifrons is easily identified if well preserved: if the dorsal spines and anteroventral hal- teroid spines are poorly preserved and (or) not ob- served, recognition of the genus can be very difficult. The specimens here questionably assigned to Spini- frons grandicosta n. sp., all poorly or incompletely preserved, had been initially assigned to the genus Peniculauris Muir-Wood and Cooper (1960), on the basis of the preserved spine arrangement. Later rec- ognition of similarity of form and other diagnostic characters permitted assignment to Spinifrons. Spinifrons grandicosta new species Plate 7, figures 1-10 Etymology of Name.—L. grandis = grand, large + L. costa = rib. Description.—Large, larger than average for genus, concavo-convex transverse shells; subpentagonal in outline, having small, rounded triangular ears. Ante- rior commissure gently rounded, not appreciably in- dented mesially. In anterior aspect moderately domed, with steep flanks; in lateral aspect tightly spiralled, geniculate, having steep anterior and posterior flanks and subparallel visceral disc and trail surfaces. Orna- ment of rugae and costae producing faintly reticulate surface posteriorly. Ventral valve spinose; dorsal valve apparently so, but spines not preserved. Umbo small, low, not protruding appreciably posterior or dorsad to hingeline. Slight fold and sulcus develop- ment. Ventral valve deeply convex; greatest height at about midvalve. Ears curving smoothly into flanks. Surface ornamented by (1) irregular concentric rugae, arising at umbo, becoming obsolete ventral of hinge, posterior to venter, (2) irregular costae, weak at umbo, but increasing in strength anteriorly, increasing in number by irregular bifurcation and intercalation, or — arising abruptly anterior of spine bases, continuing to © anterior margin; four to five in a 10 mm distance on trail. Spines (1) in ray divergent from hinge, terminat- ing laterally in sparse tuft of robust halteroid spines on ears, (2) as smaller ornament spines scattered over flanks and sulcus, on crests of costae at intersections with rugae or not, (3) as large, heavy erect halteroid spines on crests of costae near anterior margin, con-— centrated in sulcus and anteromesial portions of shell. Anterior commissure gently rounded, slightly indented in dorsal aspect. Minute open triangular delthyrium present. Dorsal valve deeply concave; greatest depth at or slightly anterior to midvalve. Ears slightly set off from visceral disc by low rounded oblique ridge. Low ob- solescent rugae, originating at umbo, covering visceral disc. Obsolescent costae, arising as fine costellae at umbo, appearing distinctly only on trail, there as broad folds separated by narrower furrows. Apparent spine bases scattered over visceral disc and trail, increasing | in size distally. Anterior margin gently rounded, very slightly mesially indented. Low fold arising at umbo, continuing across visceral disc and trail to anterior margin. Ventral interior having flattened ears, set off from visceral cavity by diductor-bounding ridges; ridges ex- tending about one-half distance across bases of ears. | | Diductor muscle scars large, elongate triangular, | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 81 striate and flabellate, anteriorly broadening, inset into valve floor. Diductors separated posteromesially by narrowly elongate, paired, dendritic adductor muscle scars, raised on slight callus platforms. Interior of ears faintly granulose, remainder of surface minutely en- dospinose, having furrows on trail reflecting exterior costation. Dorsal interior having typical dictyoclostid cardinal process: trilobed, with dorsally deflected mesially sul- cate median lobe; lateral lobes considerably reduced. Lateral ridges diverging slightly from hinge; appearing to continue across ears as low, distinct ridges; contin- ued at geniculation to about midvalve as low rounded step in shell surface. Base of cardinal process narrow- ing anteriorly to form long slender breviseptum; brev- iseptum continuing to point of geniculation, there ter- minating in high, very thin blade. Paired, broadly triangular, dendritic adductor muscle scars posteriorly flanking breviseptum, slightly raised on thin callus platforms. Brachial ridges given off horizontally; nar- rowly looped anteriorly. Surface granulose posterior to brachial ridges, smoother within brachial ridge loops; remainder minutely endospinose; endospines semierect, anteriorly directed, on trail arising from costae; costae reflecting exterior ornament. Measurements (in mm).— Dorsal Surface Valve Hinge Mid- Thick- Length Length Length Width Width Height ness Loca.ity 13 USNM 221258 42.9, —_— = 60.6.1 46. De — USNM 221259 43.8 90. 33.4 63.6, 48.4 32.6. 15.6, (holotype) Occurrence.—Spinifrons grandicosta n. sp. occurs at locality 13 in the Palmarito Formation. A single ven- tral valve questionably referred to the species has been recovered from locality 8. The West Texas form prob- ably most closely related to S. grandicosta, S. quad- rata Stehli (1954), is largely limited to the lower Bone Spring Formation, of Late Wolfcampian age. This age is older than that inferred for the localities in the Pal- marito in which S. grandicosta has been identified. Diagnosis.—Larger than average subquadrate Spi- nifrons having coarse, extremely irregular ornament, robust halteroid spines and relatively low profile in anterior aspect. Types.—Holotype: USNM 221259; Figured Speci- mens: USNM 221258-221260; Measured Specimens: USNM 221258, USNM 221259. Comparison.—Spinifrons grandicosta is distin- guished from S. portlockianus (Norwood and Pratten, 1855) and S. delicatula Cooper and Grant (1975) by the smaller size of the mature specimens of those species. S. magna Cooper and Grant (1975) is larger, more quadrate, and has relatively finer halteroid spines on the ears. The most similar form, S. guadratus is smaller, more finely and regularly ornamented, more steeply domed, and has lateral ridges that do not. ex- tend across the bases of the ears in the dorsal interior. It is easily distinguished from other Palmarito Dic- tyoclostinae: from Peniculauris subcostata latinamer- icana n. ssp. and R. occidentalis (Newberry, 1861) by the smaller spines on the trail of those forms; from Rugatia intermedia n. sp. and R. occidentalis by the smaller size, less quadrate outline, and lack of tufts of ear spines in those forms. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 8 1 ~ 3 medium to coarse silicification 13 1 = 1 fine silicification Spinifrons? cf. S. grandicosta new species Plate 7, figures 11-15 Description.—Large, average-sized for genus, con- cavo-convex transverse shells; subpentagonal in out- line. Lateral slopes gently rounded, venter slightly in- dented in anterior view; anterior and posterior slopes rounded in lateral view. Ears large, rounded, merging smoothly into visceral mass. Umbo low, small, pro- truding only slightly dorsal and posterior to hingeline. Distinct costae arising as costellae at umbo, increasing anteriorly in size, and in number, by intercalation and bifurcation; anteriorly of venter quite strong, coarse. Rugae, distinct posteriorly, becoming somewhat weaker anteriorly, rather abruptly dying out at venter. Both valves spinose. Ventral valve broadly convex, geniculate; greatest height at or anterior to midvalve; coarsely reticulate from umbo to venter; rugae abruptly disappearing at 82 BULLETIN 313 venter; costae anterior to venter coarse, four to five in a 10 mm distance on trail, separated by furrows about equal in width to costae. Ears broad, slightly flattened; body not appreciably indented anterior to ears. Small triangular open delthyrium. Spines (1) in ray from umbo to ears, (2) as dense tuft of coarse halteroid spines on ears, (3) as fine spines scattered over surface of visceral disc on intersections of rugae and costae. Spines on locally raised portions of costae, staggered so that no spine is concentrically adjacent to one on neighboring costa. Spines apparently rare to absent on trail. Distinct broad mesial sulcus arising at umbo, continuing to indent anterior commissure. Bro- ken-off trails common anteriorly, there forming dis- tinct overlapping lamellae. Dorsal valve slightly to deeply concave, visceral disc planar to slightly concave, junction with trail dis- tinctly geniculate. Ears flattened. Visceral disc finely reticulate; rugae fine, rather uniform; costae fine um- bonally, increasing anteriorly in size; in number by intercalation. Trail broadly costate, there commonly bearing four to six rounded costae in a 10 mm distance, costae separated by considerably narrower furrows. Narrow fold arising anterior to shallow umbonal hol- low, continuing to, and indenting anterior margin. Fine, delicate, erect spines scattered over visceral disc in rough quincunx pattern; absent or not preserved on trail. Minute lophidium, aiding in closure of ventral delthyrium. Ventral interior having raised elongate median cal- lus platform bearing paired dendritic adductor muscle scars; platform flanked by larger, anteriorly broad- ened, radially striate, triangular diductor muscle scars inset onto valve floor and lateral umbonal walls. Dis- tinct muscle-bounding ridges, non-crenulate, arising in umbo, running along posterolateral margins of diduc- tor scars, extending about one-half way across bases of ears, overhanging visceral cavity. Distinct curved ginglymus present. Ears slightly concave, smooth. Surface otherwise minutely pustulose to finely pitted. Dorsal interior having typical sessile to semi-erect, posterior- to posterodorsal-facing cardinal process myophore; myophore trilobate, with larger median lobe dorsally deflected, mesially sulcate. Shaft short to obsolete. Lateral ridges running along hinge, di- verging from hinge to bend across bases of ears; an- terior extent or continuation not observed. Broad base of cardinal process narrowed anteriorly to form slen- der low breviseptum; breviseptum terminating nearly opposite anterior margin of dorsal visceral disc in broadened, raised blade. Paired, dendritic, broadly tri- angular adductor scars posteriorly flanking brevisep- tum; scars bounded posterolaterally by low, incipient secondary septum, this arising from broad base of car- dinal process. Coarse, raised brachial ridges given off horizontally from anterior end of adductor scars, nar- rowly looped anteriorly. Measurements (in mm).— Hinge Mid- Thick- Length Width Width Height ness Loca.irTy 11 USNM 221261 40, . 30.5, 47.6), _— 13.1, USNM 221262 — 67.2, 46.5. 34. 19.0, Occurrence.—Spinifrons? cf. S. grandicosta n. sp. occurs in the Palmarito fauna at localities 3, 4 and 11. It is rather rare at localities 3 and 4 and common at locality 11. Diagnosis.—Like Spinifrons grandicosta, but aspi- nose or rarely spinose on the trails. Types.—Figured Specimens: USNM 221262-—221266; Measured Specimens: USNM 221261, 221262. Discussion.—Because it lacked the anteroventral trail spines diagnostic of Spinifrons, I first assigned this form to Peniculauris Muir-Wood and Cooper (1960). Later comparison with specimens assigned to S. grandicosta, showed great similarities, but no exact correspondence. In the absence of any traces of ven- tral trail spines, these forms can only questionably be assigned to Spinifrons, although they share many of the specific characters of S. grandicosta. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 3 l a = fine silicification 4 l - = medium to coarse silicification 11 7 _— — fine to coarse silicification Suborder OLDHAMINIDINA Williams, 1953 Superfamily LYTTONIACEA Waagen, 1883 Family LYTTONIIDAE Waagen, 1883 Discussion.—Worldwide distribution of lyttontid brachiopods made possible prediction of their pres- ence in rocks of proper age and lithotype in Venezue- la. Their previous absence from reports and faunal lists was probably due, among many other factors, to the search for fossils chiefly in rocks that preserved soft-bottom assemblages. The environments repre- sented by such rocks lacked the hard substrate nec- essary for the cemented attachment of the lyttontids (Hoover, 1975). Genus COLLEMATARIA Cooper and Grant, 1974 Type Species.—Collemataria elongata Cooper and Grant, 1974, p. 137, pl. 139, figs. 11, 17-20; pl. 170, PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 83 figs. 1-16; pl. 171, figs. 1-18; pl. 172, figs. 1-16; pl. 173, figs. 1-40; pl. 181, figs. 12-15; pl. 183, figs. 22- 23; pl. 191, fig. 10. Diagnosis.—Usually large Lyttoniidae having pro- gressive lateral septa, posterior callus flap for attach- ment, and hinge at margin of cowl. Occurrence.—Specimens referable to Collemataria have been reported to date only from the West Texas area, in rocks of from Wolfcampian (Skinner Ranch Formation) to Guadalupian (Bell Canyon and Capitan Formations) age. Comparison.—Collemataria might best be called the “‘North American Leptodus,’’ since it includes many of the Western United States species formerly assigned to that genus. Many of these species were removed from Leptodus Kayser (in Richthofen, 1882) upon recent study of type specimens of the genus that revealed the presence of a ventral diductor muscle at- tachment area in that form. This attachment, bounded by shell plates, is a feature not seen in many of the American forms. The genus Collemataria was there- fore erected to house these Leptodus-like forms which had no well-defined muscle attachment areas. Collemataria may be distinguished from all Lytto- niidae except Leptodus and Petasmaia Cooper and Grant (1969) by the manner of attachment to the sub- strate. In these three genera, the callus shell growth above the ventral valve hinge is posterior, forming a flap, which is reflexed ventrally and joins with the apex as a secondary site of shell attachment. The other gen- era of the Lyttoniidae have a similar shell structure, but it grows anteriorly, forming a cowl, and giving the entire shell a more conical aspect. Both Leptodus and Petasmaia have so-called ‘‘dental plates’’ (muscle field bounding ridges), located at either side of the midline in the ventral interior apex. While those of Petasmaia are quite strong and well-defined, those of Leptodus are less so. Collemataria rarely exhibits any indication of the scope of its diductor musculature, beyond the shape and form of its cardinal process. Collemataria venezuelensis new species Plate 7, figures 16-23 Lyttoniid specimen of Hoover, 1975, p. 152, text-fig. 2. Etymology of Name.—Venezuela + L. -ensis = at the place of. Description.—Small, commonly low, relatively broad, ostreiform shells having irregular, concentri- cally wrinkled exterior. Attached at apex and by everted posterior callus flap, cicatrix commonly at considerable angle to plane of shell. Valve floor flat or concave, with margins commonly flexed dorsally. Ventral interior having narrow, straight hinge, inset at junction of valve and relatively large posterior flap; ventrally bearing small symmetrical articulatory pro- cesses. No apparent muscle scars or plates defining muscle field. Seven to twelve, commonly eight to nine longitudinally compressed, angustilobate to solidisep- tate septa of subuniform height, having posteriorly fluted or beaded faces. Posteriormost two to three lat- eral septa approaching anguliseptate condition. Well- defined median ridge extending from just anterior to hingeline as sharp solidiseptate form, commonly me- sially grooved; narrowly bifurcate anteriorly. Dorsal valve small, thin, having narrow straight hinge; commonly bent at high (nearly 90°) angle near bifurcation to conform to similar deflection in ventral valve. Surface smooth, rounded, having low median depression extending anteriorly from hinge to bifur- cation. Bifurcation persistent, not narrowed or healed anteriorly. Lateral lobes separate, distinct, not healed laterally. Dorsal interior having small, commonly eccentri- cally positioned, bilobate to quadrilobate cardinal pro- cess, set on very short shaft. Narrow median ridge arising at base of cardinal process, doubled or longi- tudinally grooved and broadening anteriorly up to bi- furcation. Lobes concave, commonly having inner lin- ear or beaded marginal rim. Measurements (in mm).— Maximum Length Width Height LOCALITY 6 (block A) USNM 221267 16.3, 20.8), 6.8), USNM 221268 20.1, 20.6, Sth USNM 221269 26.6, 20.7, 14.0, (holotype) USNM 221270 32.4, 24.4, 5.8}, Occurrence.—Collemataria venezuelensis n. sp. has only been recovered from locality 6, block A. Blocks B and C from the same locality contain no traces of the form, indicating its patchy distribution. The most similar previously described species of the genus, C. spatulata Cooper and Grant (1974) is known from the Bell Canyon and Capitan Formations (Guadalupian) of West Texas. Such an age assignment is not incon- sistent with that provided by other biostratigraphic in- dicators for this Palmarito locality. Diagnosis.—Small Collemataria, having discrete low lateral lobes and narrow, uniform lateral septa. Ventral valve cemented to substrate near beak only; remainder of valve commonly at a high angle to sub- strate. Types.—Holotype: USNM 221269; Figured Speci- 84 BULLETIN 313 mens: USNM 221269-221274; Measured Specimens: USNM 221267-221270. Comparison.—The Palmarito specimens are easily differentiated from other species of Collemataria. C. americana (Girty, 1909) is similar in overall appear- ance but tends to be larger and to have a more gran- ulose interseptal area in the ventral interior than does C. venezuelensis. C. batilliformis Cooper and Grant (1974) is typically anteriorly constricted, in some cases to such a degree that the anterior margin is tubiliform. C. elongata Cooper and Grant (1974) and C. gregaria Cooper and Grant (1974) are much larger than C. ven- ezuelensis: the former also differs in its higher lateral septa, while the lateral lobes of the dorsal valve are commonly merged in the latter. C. irregularis Cooper and Grant (1974) in general has a deeper shell, with greater development of the cowl. C. marshalli (Stehli, 1954) has thick, high lateral septa, quite unlike the narrow, more uniform ones of C. venezuelensis. C. platys Cooper and Grant (1974) is commonly cemented to the substrate over much of its ventral surface, un- like C. venezuelensis, in which attachment is limited to the apex and posterior flap, while the remainder of the shell lies at a considerable angle to that plane. C. spatulata is commonly somewhat larger and flatter than C. venezuelensis, though of the West Texas forms it is the most similar to C. venezuelensis. Discussion.—The present collection of C. venezue- lensis consists of just over forty specimens, many of them fragmentary. Only two sets of articulated valves were recovered, and only a single set is separable so that the interior may be examined. Most specimens are missing much of the lateral and anterior margins. The remainder of the brachiopod assemblage col- lected from locality 6, blocks A, B and C consists of small forms. Some of these may be immature, though in some cases distinct evidence of maturity is present (e.g., loop development in Terebratulida). C. vene- zuelensis is by far the largest brachiopod present, al- though it is smaller than many previously described lyttoniids. Although some of the specimens bear ju- venile characters (predominance of angustilobate, as opposed to solidiseptate septa; small, commonly bi- lobate, rather than quadrilobate cardinal process myo- phore), sufficient numbers of specimens are present to demonstrate that mature individuals are also repre- sented. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 6 (block A) 1 10 44 fine silicification Order RHYNCHONELLIDA Kuhn, 1949 Superfamily RHYNCHONELLACEA Gray, 1848 Family PONTISIIDAE Cooper and Grant, 1976a Discussion.—This family, created from part of Wel- lerellidae (sensu lato) includes forms which externally resemble Wellerella Dunbar and Condra (1932) (sensu stricto) but lack the dorsal median septum character- istic of wellerellids. In Wellerella (sensu stricto) how- ever, this septum is limited to the apical portion of the valve. In the National collections, some specimens identified as W. girtyi Cooper and Grant (1976a) have such a small dorsal median septum that it cannot readi- ly be discerned; in the same collection, specimens of Pontisia stehlii Cooper and Grant (1969), an external homeomorph of W. girtyi, have a ‘“‘median ridge”’ that rises apically to join the underside of the hinge plate in the dorsal valve, a condition most atypical for that genus. Cooper and Grant (1976a, p. 2019) state In old specimens [of Pontisia] the low [median] ridge often swells to a boss posteriorly under the hinge plate. This simulates Wellerella but the boss is never a septum although it may help to support the hinge plate. While the Pontisiidae and Wellerellidae appear to intergrade in terms of development of the median sep- — tum, they include too diverse a group of forms to be | considered as a single family. Hence the somewhat artificial distinction is necessary, to allow recognition of workable, if not strictly valid family groupings. The spatio-temporal continuum of organic life may provide a more-or-less continuous gradation of phenotypes. When such a data set is incomplete, distinctions ap- pear clearcut; as sampling becomes more comprehen- sive however, the sharp edges of differentiation be- | come somewhat more rounded. Genus PONTISIA Cooper and Grant, 1969 Type Species.—Pontisia stehlii Cooper and Grant, 1969, p. 13, pl. 4, figs. 7-10. Diagnosis.—Pontisiids with hinge plate similar to that of Wellerella but not supported by a median sep- tum. Occurrence.—Pontisia is known from North, Cen- tral and South America, and has been reported in Thailand (Grant, 1976). Its range almost certainly is | greater than this, but since familial and generic dis- tinctions are based upon internal characters, many © previously described forms [e.g., Wellerella (sensu — lato)] cannot properly be reassigned until extensive | additional preparation has been undertaken. | Comparison.—Pontisia may be distinguished with | ease from other genera of the Pontisiidae: Lirellaria | Cooper and Grant (1976a) is costellate, while Divari- | | | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 85 costa Cooper and Grant (1969) has bifurcating costae; a number of the median costae of the dorsal fold of Antronaria Cooper and Grant (1976a) are character- istically depressed; Aphaurosia Cooper and Grant (1976a) has irregular radial ornament and a more rounded outline; species of Acolosia Cooper and Grant (1976a) are commonly smaller and smoother than those of Pontisia; Anteridocus Cooper and Grant (1976a) has only rudimentary dental plates, in contrast to the strong ones seen in species of Pontisia. As stat- ed above, Pontisia may be distinguished from most species of Wellerella, by the presence of a dorsal me- dian septum in those forms. Some species of Pontisia may resemble Allorhynchus Weller (1910), in that the radial ornament arises at or just anterior to the beaks, but the presence of an undivided hinge plate clearly permits their assignment to Pontisia. Pontisia stehlii Cooper and Grant Plate 7, figures 39-48 Pugnoides texanus R. E. King (non Shumard, 1860), 1931, p. 108, pl. 34, figs. 5-9. Pugnoides elegans R. E. King (non Girty, 1909) part, 1931, p. 106, pl. 33, figs. 12, 13; pl. 34, fig. 4 (non figs. 2, 3). Pontisia stehlii Cooper and Grant, 1969, p. 13, pl. 4, figs. 7-10. Pontisia stehlii stehlii Cooper and Grant, 1976a, p. 2027, pl. 517, figs. 21-25, 38-47; pl. 533, figs. 40-61; pl. 534, figs. 1-49; pl. 552, fig. 14. Description.—Small to medium sized, average to large for genus, unequally biconvex, in mature ex- amples somewhat bulbous, having rounded trigonal to subpentagonal outline; dorsal valve much deeper than ventral. Lateral profile subtrigonal; anterior commis- sure uniplicate; fold low to moderately high, common- ly beginning about 5 mm anterior to dorsal beak; pro- file flattened near beak, abruptly convex anteriorly; sulcus shallow to moderately deep, commonly begin- ning about 9 mm anterior to ventral beak. Anterior face commonly rounded in lateral view, rarely slightly facetted in mature to gerontic individuals. Costae strong, broad, crowded, commonly angular, less com- monly rounded in section, separated by angular troughs of width equal to costae; commonly arising 5 to 7 mm from ventral beak, numbering three to five on dorsal fold, three to five on each flank; costae on flanks less pronounced than mesially. Concentric or- nament absent; growth lines faint, rare. Ventral valve low, but strongly convex through sul- cus, slightly convex on flanks; beak sharp, attenuate, commonly parallel to hingeline; lateral pseudointer- areas narrow, partly covered by overlap of dorsal valve. Delthyrium narrow, open, basically closed by disjunct trapezoidal deltidial plates; pedicle foramen elongate, oval. Dorsal valve moderately to strongly convex trans- versely and longitudinally, more so in mature individ- uals; non-costate umbo may be slightly indented. Ventral interior having sides of delthyrium widely diverging anterior to deltidial plates; teeth elongate, supported by strong vertical dental plates reaching floor of valve. Muscle field poorly impressed. Dorsal interior having undivided but anteriorly notched triangular hinge plate, bounded laterally by deep, anteriorly more massive sockets; apparent fal- cifer crura projecting anteriorly; extremities not ob- served. Low median ridge on valve floor separating elongate oval, apparently striate adductor scars. Measurements (in mm).— Costal Origin Maxi- Number Number Distance Dorsal Maxi- mum of of from Valve mum Thick- Costae Ventral Ventral Length Length Width ness on Fold Costae Beak Loca.ity 8 USNM 221282 11.3 9.6 10.7 Weil 3 11 6, USNM 221283 12.1 10.7 12.5 10.6 11 Ss Locatity 10 USNM 221280 i13}.5}. 11.9, 16.0, 12.4... 3 12 Te USNM 221281 14.5, 12518 16.2, 12 3 12 Te Locatity 11 USNM 221275 8.5 _— 8.6 — — 14 6 USNM 221276 8.9, 8.0 8.6 5.0 3 11 6 USNM 221277 9.8 8.6 9.2 3.8 3 11 6 USNM 221278 12.4 10.7 11.1 8.7 5 13 7 USNM 221279 16.1, 14.1, 1S25¢ 12.4, 3 14 Th 86 Occurrence.—Pontisia stehlii has been recovered in the West Texas region from rocks ranging in age from Leonardian (Cathedral Mountain and Road Canyon Formations) to Early Guadalupian (middle Word For- mation). In the Palmarito Formation it has been re- covered from localities 8, 10 and 11. It is not a com- mon faunal element at any of these localities. A Leonardian to Early Guadalupian age is consistent with other biostratigraphic indicators. Diagnosis.—Large Pontisia having deep dorsal valve and closely crowded angular costae, but smooth beaks and umbonal areas. Types.—Figured Specimens: USNM 221277-221280, USNM 221283, USNM 221284; Measured Specimens: USNM 221275221283. Comparison.—Mature individuals of P. franklinen- sis Cooper and Grant (1976a), P. nanas (Stehli, 1954), P. parva Cooper and Grant (1976a) and P. wolfcam- pensis Cooper and Grant (1976a) are markedly smaller than similar growth stages in P. stehlii. The low dorsal valve of P. kingi Cooper and Grant (1976a) easily dis- tinguishes that species from P. stehlii, and the larger, coarser and sparser costae of P. costata Cooper and Grant (1976a), P. magnicostata Cooper and Grant (1976a) and P. truncata Cooper and Grant (1976a) ef- fectively distinguish those species. The costae of P. longicosta (Stehli, 1954) arise much closer to the beaks than do those of P. stehlii. P. ventricola Cooper and Grant (1976a) presents a much smoother exterior than does P. stehlii. P. robusta Cooper and Grant (1976a) is less globose and more transverse than most speci- mens of P. stehlii. P. stehlii is similar to Pontisia sp. Stehli and Grant (1970) from the Chochal Limestone (Leonardian) of Guatemala, but differs from that poorly known species in its more globose form, broader and higher fold and sulcus, and its somewhat more pronounced ornament. P. stehlii may easily be differentiated from a small- er, paucicostate, less globose Pontisia from the Co- pacabana Formation (Wolfcampian) of the Lake Titi- caca region, Peru and Bolivia. Discussion.—It may be considered by some unwar- ranted to assign the same species name to forms from such presently distant areas as Venezuela and West Texas. In this case however, the morphology of indi- BULLETIN 313 viduals and the variation in samples of populations are so strikingly similar that such a conclusion is inescap- able. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 8 6 — — fine silicification 10 3} 1 — fine silicification 11 11 5) 6 fine silicification Pontisia cf. P. stehlii tumidosa Cooper and Grant Plate 7, figures 24-36 cf. Pontisia stehlii tumidosa Cooper and Grant, 1976a, p. 2028, pl. 510, figs. 56-62; pl. 535, figs. 52-66. Description.—Small- to medium-sized, average for — genus, subtrigonal to subpentagonal in outline, dorsal valve deeper than ventral. Sides rounded, greatest width at or anterior to midvalve; anterior margin mod- erately rounded to subtruncate; anterior commissure uniplicate. Beak short, sharply angular, having elon- gate pedicle foramen and elevated, short, disjunct del- — tidial plates. Surface variably costate, having from three to six, commonly three, rounded to subangular — costae on the dorsal fold, and four on each flank. In- tercostal furrows narrower than costae. Ventral valve moderately convex in lateral profile; broadly and gently convex in anterior profile. Sulcus originating near midvalve; broad, shallow, poorly to moderately defined. Tongue moderately strongly ge- niculated, convex in lateral aspect. Costae commonly arising about 4 mm anterior to ventral beak. Dorsal valve moderately convex in lateral view, but strongly domed in anterior view, having nearly vertical flanks. Umbonal region gently convex; fold originating near midvalve, moderately wide, only slightly elevated above flanks through entire length, flat-crested in ma- ture specimens. Interior as for Pontisia stehlii. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 87 Measurements (in mm).— Costal Origin Maxi- Number Number Distance Dorsal Maxi mum of of from Valve mum Thick- Costae Ventral Ventral Length Length Width ness of Fold Costae Beak LocaLity 3 USNM 221285 4.9 4.4 4.2 322 3 9. 4. USNM 221286 6.0 aio) Set 4.1 4 13, 4. USNM 221287 6.7 oul TP 55) 3 13 4 USNM 221288 7.0 6.5 RES 4.6 3 13 4. USNM 221289 Wes} 6.4 7.4 5.0 4 15 4 USNM 221290 7.3 6.5 Goll Sul 3 14 4 USNM 221291 75 6.5 7.7 5.9 4 13 4 USNM 221292 7.6 6.4 7.9 5.8 3 13 4 USNM 221293 7.6 7.0 7.6 6.0 3 13 4 USNM 221294 8.1, 7.4y 8.5. 6.8. 4 rie 4 USNM 221295 8.6 cS) 8.2 eh 4 14 4 USNM 221296 8.6, 7.6 9.6 6.8 5 16 3\, USNM 221297 10.5,. 9.3. 13.3 9.3 6 14 4. Occurrence.—Pontisia stehlii tumidosa occurs in Material.— the Cathedral Mountain and Road Canyon Formations a si s) rticu- (Leonardian) of West Texas. In the Palmarito For- Eee es eA wena Type of mation the form tentatively referred to this subspecies ity Wakes Walkee Wakes Procemation has been recovered only from locality 3, where it is 5 7 " 7" AGAR common. A Leonardian age for that assemblage is not inconsistent with other biostratigraphic indicators. Diagnosis.—Rotund and bulbous Pontisia having costae extended to but not onto the beaks. Types.—Figured Specimens: USNM 221285, USNM 221286, USNM 221289, USNM 221292, USNM 221295, USNM 221298; Measured Specimens: USNM 221285—221297. Comparison.—Pontisia stehlii tumidosa is distin- guished from other West Texas Pontisia species by its more dense costation and more globular profile. It is distinguished from P. stehlii stehlii Cooper and Grant (1969) by its smaller average size, lower fold, shallow- er sulcus, more convex ventral valve and more exten- sive costation. The Venezuelan form here referred tentatively to the subspecies differs from that West Texas form in having apparent disjunct rather than conjunct deltidial plates, and by having a slightly more transverse outline, although this latter feature may in part be due to crushing. RHYNCHONELLACEA family uncertain Plate 7, figures 49-55 Discussion.—A number of small shells, trigonal in outline and bearing characteristic rhynchonellacean costation were recovered from Palmarito locality 6, blocks B & C, and locality 10. The latter differ from Pontisia stehlii Cooper and Grant (1969), in their smaller size, more extensive, finer costation, and less globose profile, and from Pontisia cf. P. stehlii tumi- dosa Cooper and Grant (1976a) in their more elongate, more distinctly trigonal outline, and their less globose profile. Their profile suggests they may be juveniles. No apical interiors were sufficiently well preserved to permit determination of familial affinities. The material 88 BULLETIN 313 from locality 6 is so fragmentary (a single ventral valve is the only unbroken specimen) that taxonomic con- formity with those from locality 10 cannot be assured. Types.—Figured Specimens: USNM 221300-221302; Measured Specimens: USNM 221299-221303. Measurements (in mm)— Costal Origin Maxi- Bs Distance Dorsal Maxi mum Number of Costae from Valve mum Thick- Ventral Length Length Width ness Ventral On Fold Beak Loca.ity 10 USNM 221299 5.98 5.4 5) 7/ 3.1 16 4 4 USNM 221300 6.0 5.0 5.0 Soll 14, 3 4. USNM 221301 6.6 5.8 7.0 4.5 16 4 4. USNM 221302 6.9 5.9 se) 3.6 16 4 4 USNM 221303 6.9 6.2 6.1 4.0 14 3 4 Material.— Hustedia hyporhachis new species ee Plate 8, figures 1-18 lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation Etymology of Name.—Gr. hypo = smaller; Gr. 6 (block B) = 2 2 fine silicification rhachis = backbone, midrib. 6 (block C) = = 4 fine silicification Description.—Small to medium-sized, average for 10 5 _ _ fine silicification Order SPIRIFERIDA Waagen, 1883 Suborder RETZIIDINA Boucot, Johnson and Staton, 1964 Superfamily RETZIACEA Waagen, 1883 Family RETZIIDAE Waagen, 1883 Genus HUSTEDIA Hall and Clarke, 1893 Types Species.—Terebratula mormoni Marcou, 1858, p. 51, pl. 6, figs. 1la—c. Diagnosis.— Small, strongly costate ... [Retziidae] with a rostrate pedicle beak and a flat symphytium. (Stehli, 1954, p. 350) Occurrence.—Hustedia is known from rocks vary- ing in age from Mississippian through Permian, in Eu- rope, Asia, and the Western Hemisphere. In the Perm- ian its distribution appears to have been tropical to subtropical: it does not appear in truly Boreal assem- blages. It is probably the most common brachiopod in the Palmarito fauna, occurring at localities 1, 3, 6, 8, 10, 11 and 13, and being the dominant faunal element in assemblage 10. Comparison.—The family Retziidae is rather poorly represented in the Upper Paleozoic, only two of nine genera assigned to it in the Treatise (Williams et al., 1965) falling within that time range. Only Hustedia and Thedusia Cooper and Grant (1976b), represent the family in the Permian. Thedusia is easily distinguished from Hustedia by its generally smaller size, elongate beak, bisulcate valves and emarginated anterior. genus, strongly biconvex; outline elongate suboval, normally widest at or slightly anterior to midlength; | commissure serrate, anteriorly bearing low fold and sulcus; costae commonly rounded to square-topped, — from 11 to 16, commonly 13 on dorsal valve; median costa of dorsal valve depressed near beak in juveniles, anteriorly somewhat broader, more flat-topped than lateral costae; median trough of ventral valve slightly wider than lateral troughs, most mature specimens bearing a very weak median ridge anteriorly; fold and sulcus development encompassing mesial three to four costae; growth lines fine, rarely visible, growth lami- nae weak, normally observed only near anterior mar- gins. Ventral valve deepest near midvalve, anterior to dorsal umbo; beak somewhat long, blunt, suberect to’ erect; foramen round, of normal size, permesothyri- did; symphytium longitudinally concave. Dorsal valve deepest just anterior to umbo, com-. monly posterior to greatest width of shell, commonly slightly less convex than ventral valve; beak blunt, | curving only slightly posterior to hinge. Ventral interior having blunt, transverse teeth; ped-| icle collar rarely preserved; crests of internal costae’ flat to slightly concave, flanks of internal costae of anterior third to half of valve bearing one to several. short lirae that may crenulate anterior margin. I Dorsal interior having moderately deep sockets; hinge plate short, only slightly recurved, projecting, anteroventrally, median portion near base extended as’ short curved ligulate process projecting ao ) | } PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 89 trally; median septum very short, low, thin, apically side, axis of spire at right angles to shell length across confined, extending at most 1-2 mm along valve floor; widest part; costae and intercostal lirae as in ventral crura short, projecting ventrally; mesial portions of valve. spiralium not preserved intact, up to ten loops on each Measurements (in mm).— Dorsal Number of Total Valve Total Hinge Thick- Dorsal Length Length Width Width ness Costae Loca.ity 10 USNM 221304 3.6 7x) 2-9 1.0 1.7 13 USNM 221305 3.9 3.0 3. 1.4 2.2 15 USNM 221306 5.0 4.0 4.0 1.5 3.2 15 USNM 221307 5.1 4.0 4.4 1.7 3.0 13 USNM 221308 523 4.2 4.2 1.6 2.8 13 USNM 221309 5.4 4.2 4.7 1.7 3.4 13 USNM 221310 5.5 4.4 4.8 1.8 3.2 13 USNM 221311 Sh// 4.7 3:3 Noa 3.6 13 USNM 221312 6.3, D2 4.8 1.5 3.8 13 USNM 221313 6.7 5.0 5.0 1.8 3.7 13 USNM 221314 6.8 6.0 5.3 2.2 4.0 15 USNM 221315 7.0 6.0 =) 2.0 4.4 15 USNM 221316 7.0 5.9 6.2 2.0 4.1 15 USNM 221317 7.1 5.8 SD) 1.8 4.2 13 USNM 221318 7.1 529) 5.5 il57/ 4.5 13 USNM 221319 73 6.0 6.3 D5) 4.8 13 USNM 221320 7.4 6.3 6.3 1E7 4.5 13 USNM 221321 7.4 6.5 6.3 1.8 4.6 13 USNM 221322 165) 6.0 4.5 1.8 4.0 13 USNM 221323 7.5 6.0 6.6 ep) S74 13 USNM 221324 We) 6.4 5.6 1.8 4.2 13 USNM 221325 7.6 6.1 6.8 2.0 4.8 11 USNM 221326 7.8 6.1 6.2 2.1 4.9 13 USNM 221327 8.3 6.6 7.1 2.4 5.0 13 USNM 221328 8.5. 7.0 6.4 17 4.8 13 USNM 221329 8.5 7.0 Uc3} 2.4 Sell 15 USNM 221330 8.7 6.8 Tal 2.2 5.5 13 USNM 221331 8.8 7.0 7.1 2.4 5.7 13 USNM 221332 8.8 7.5 Hel DED She 13 USNM 221333 9.0 Ue) 7.8 2.0 5.5 13 USNM 221334 O28 Tede 7.8 Ze 5.7 13 USNM 221335 Oy 7.8 7.8 2.2 5:5 13 USNM 221336 9.3 7.6 Wee? 2.2 Shp) 13 USNM 221337 9.5 Ws) 8.2 es) 6.0 15 USNM 221338 95 7.8 Vell 1.8 5.8 13 USNM 221339 9.6 8.0 8.2 2.2 Sell 13 USNM 221340 9.7 7.8 Hell 2.0. 5.8 13 USNM 221341 OF 8.0 8.3 2.8 6.4 15 USNM 221342 OF7. 8.1 8.4 3.0 6.3 13 USNM 221343 Oi 8.3 7.8 2.0 5.8 13 USNM 221344 9.8 7.8 8.2 23 6.0 13 USNM 221345 10.0 8.0 935 2.2 6.2 13 USNM 221346 10.0 8.2 UP 2.3 6.5 13 USNM 221347 10.3 8.8 9.7 3.0 6.9 15 USNM 221348 10.5 8.7 8.7 Dll 7.1 13 USNM 221349 10.5 8.7 91 2.9 S)s1/ 13 USNM 221350 11.0 OLS) 9.1 2.6 Ze 13 USNM 221351 11.3 9.6 9.1 3:2 6.4 13 USNM 221352 11.3 9.8 TES) 2.8 7.8 13 USNM 221353 11.3 9.8 O51 3.2 7.5 13 USNM 221354 11.4 9.9 10.0 3.1 7.6 13 USNM 221355 11.7 10.1 8.9 Sill ee) 13 USNM 221356 12.0 10.3 9°5 3.0 7.8 13 90 BULLETIN 313 Dorsal Number of Total Valve Total Hinge Thick- Dorsal Length Length Width Width ness Costae USNM 221357 12.1 9.8 9.1 3.4 Ve? iN7/ USNM 221358 1252 10.3 9.6 3.0 7.8 15 USNM 221359 12.4 10.5 9.8 3.4 8.0 13 USNM 221360 25) 10.5 10.1 3303) 8.1 13 USNM 221361 17225) 10.8 10.6 BE 7.9 13 USNM 221362 12.7 11.0 10.5 3:3 8.8 13 USNM 221363 12.9 10.8 11.0 3.2 9.2 13 USNM 221364 12.9 11.1 10.6 3.5 8.1 13 USNM 221365 13.1 11.1 10.6 3.3 8.5 13 USNM 221366 [372 11.2 10.1 8)55) 8.6 13 USNM 221367 13.3 11.1 10.8 3.4 8.4 13 USNM 221368 13.3 11.6 11.2 353 8.9 13 USNM 221369 13.3 11.8 i283} 2.8 8.9 11 USNM 221370 13.4 11.3 10.8 3.5 9.8 13 USNM 221371 13.5 11.7 iVi1.3} 3.7) 8.6 13 USNM 221372 13.5 11.8 11.7 3.4 9.2 13 USNM 221373 13.5 11.4 10.9 3.6 8.4 13 USNM 221374 13.6 11.7 11.5 3.8 9.6 16 USNM 221375 13.8 11.7 11.0 3.6 8.2 14 USNM 221376 13.8 11.8 10.5 aml 10.0 13 USNM 221377 13.8 12.0 11.5 3.4 10.0 13 USNM 221378 14.0 12.0 12.1 3\7/ 9.8 15 USNM 221379 14.2 11.9 11.8 35) 07 13 USNM 221380 14.2 12.1 12.6 317/ 9.8 13 USNM 221381 14.3 12a 10.8 3.0 9.0 13 USNM 221382 14.3 12.2 10.6 32 10.4 15 USNM 221383 14.4 12.1 11.1 33,5) 8.4 13 USNM 221384 14.6 12.6 Lilet 3.2 93) 13 USNM 221385 14.6 7) 11.2 3.4 9.8 13 USNM 221386 14.8 2-7) Mb, 7/ 3.6 10.4 15S USNM 221387 15.0 12.7 11.7 3.6 10.1 15 USNM 221388 15.0 12.7 13.4 4.5 11.0 13 USNM 221389 15.0 12.9 12.4 4.1 10.6 15 USNM 221390 15.0 13.0 12.9 3.8 9.6 13 USNM 221391 15.0 13.1 10.8 2.6 11.2 13 USNM 221392 152 1-5) 11.5 4.3 10.5 13 USNM 221393 1S 13.0 12.2 3.4 10.2 13 USNM 221394 15.2 13.2 12.3 3).5) 10.7 13 USNM 221395 15.3 12.9 13.2 3.8 12.1 13 USNM 221396 15.5 113}33 12.8 4.4 11.1 15 USNM 221397 15.6 135 ES 4.0 123 13 USNM 221398 15.6 13.5 rt 7/ 2.6 10.3 13 USNM 221399 16.0 13.4 22 4.1 10.7 15 USNM 221400 16.1 13.7 11.9 3}5) 12.1 13 USNM 221401 16.3 14.0 12.8 3.6 11.0 13 (holotype) USNM 221402 16.4 13.7 3.3 4.3 72 USNM 221403 16.7 14.7 12 4.1 0 3 Occurrence.—Hustedia hyporhachis has been re- covered from localities 3, 10, 11 and 13 in the Pal- marito Formation. Juvenile specimens questionably referable to the species, resembling juveniles from lo- calities 10 and 13, were recovered from locality 6, blocks A and C. H. hyporhachis is uncommon in the assemblages at localities 3, 6 and 11, and common to abundant in those of localities 10 and 13. At locality 10 it dominates the fauna. The most closely related West Texas form, H. con- suta Cooper and Grant (1976b) has been recovered ! from the upper portion of the Cathedral Mountain For- mation, and from the Road Canyon and Cibolo For- | mations, all of Leonardian age. Such an age assign- PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 9] ment is not inconsistent with other biostratigraphic indicators in the Palmarito faunal assemblages. Diagnosis.—Average-sized, strongly convex Hus- tedia, having low, rounded costae and a thin median ridge in the median trough of the ventral exterior. Types.—Holotype: USNM 221401; Figured Speci- mens: USNM 221308, USNM 221324, USNM 221335, USNM 221339, USNM 221352, USNM 221354, USNM 221358, USNM 221370, USNM 221386, USNM 221399, USNM 221401, USNM 221404- 221406; Measured Specimens: USNM 221304-221403. Comparison.—H. hyporhachis may be distin- guished from H. crepax Cooper and Grant (1976b), H. culcitula Cooper and Grant (1976b) and H. trita Cooper and Grant (1976b) by the absence of striae on the internal costal flanks in those forms. The smaller size of mature individuals of H. bipartita Girty (1909, H. catella Cooper and Grant (1976b), H. hapala Coo- per and Grant (1976b), H. inconspicua Cooper and Grant (1976b), H. lusca Cooper and Grant (1976b), H. narinosa Cooper and Grant (1976b), and H. trisecta Cooper and Grant (1976b), and the larger size of ma- ture individuals of H. citeria Cooper and Grant (1976b) and H. rupinata Cooper and Grant (1976b) effectively distinguish those species from H. hypo- rhachis. The smaller average number of costae in H. cepacea Cooper and Grant (1976b), H. citeria, H. compressa Cooper and Grant (1976b), H. consuta Cooper and Grant (1976b), H. decollatensis Cooper and Grant (1976b), H. opsia Cooper and Grant (1976b), H. samiata Cooper and Grant (1976b), H. spicata Cooper and Grant (1976b), and H. tomea Coo- per and Grant (1976b) and greater average number of costae of H. cuneata Cooper and Grant (1976b), H. huecoensis R. E. King (1931) and H. stataria Cooper and Grant (1976b) distinguish those forms from H. hyporhachis. The lamellose anterior and short median costa of H. demissa Cooper and Grant (1976b) effec- tively distinguishes that form, while the thickened shell of H. connorsi Cooper and Grant (1976b) distin- guishes that form. The presence of obvious growth lines on H. ampullacea Cooper and Grant (1976b), H. glomerosa Cooper and Grant (1976b), H. hessensis R. E. King (1931), H. pugilla Cooper and Grant (1976b) and H. sculptilis Cooper and Grant (1976b) distin- guishes those species from H. hyporhachis. H. hy- porhachis differs from all West Texas species but H. consuta in bearing the thin median lira in the ventral median exterior trough, and differs from that species in its lower, more rounded, and somewhat more nu- merous costae. H. hyporhachis generally resembles H. grandicosta (Davidson, 1862) from the Upper Productus Lime- stone of the Salt Range, but differs, bearing a mesial ridge in the median ventral exterior trough. It is similar to H. sicuaniensis Chronic (1949) from the Copaca- bana Formation of Peru, which appears to have a weak median ventral mesial lira (Newell, Chronic ef al., 1953, pl. 17, fig. 7b), but differs from that species in its posteriorly indented dorsal valve, larger mature in- dividuals, and the presence of striations on the flanks of the internal costae, which H. sicuaniensis does not appear to have (Cooper and Grant, 1976b, p. 2763). Discussion.—The taxonomically significant features of the species of Hustedia are commonly quite subtle. Assignment to species is a difficult task requiring ex- amination of large population samples, in order to de- termine the size, form and characteristics of juvenile and mature individuals, and the ranges of variation of taxonomically significant characters at various growth stages and throughout ontogeny. Without such a large suite, proper placement of isolated specimens within an ontogenetic framework, and consequently specific identification, can be seriously hampered. In H. hy- porhachis, three such characters (length, width, thick- ness) are related in a systematic manner. Text-figure 11 shows the relationships of these parameters for two population samples of H. hyporhachis (locs. 10 and 13) and a single sample of H. consuta. It may easily be seen that there is a linear relationship between length and width during ontogeny, while the relation- ship between length and thickness is non-allometric, thickness increasing little during early as compared to later stages of ontogeny. The latter relation is subtle, but can be seen in all three plots, and is a common ontogenetic strategy in many groups of brachiopods, indicating that there is some threshold size which must be attained before substantial increase in the internal volume of the shell can be initiated. The difference in dispersion of the plots from local- ities 10 and 13 may possibly be explained by exami- nation of the overall character of those assemblages. At locality 10, H. hyporhachis is the dominant bra- chiopod present: large numbers of individuals com- peted for the available living space, and were often closely crowded together. Such close proximity may influence the shape of mature shells by randomly lim- iting directional growth. At locality 13 however, no such crowding appears to have occurred, although the assemblage is unquestionably autochthonous. Shells in such an uncrowded environment would be free to follow an “‘ideal’’ growth plan, and there would be less deviation from their standard mode of ontogenetic development. The appearance of internal striations on the inter- costal flanks may be of considerable stratigraphic sig- 92 BULLETIN 313 Text-figure 11.—Scattergrams of dimensions of two population samples of Hustedia hyporhachis n. sp. from Venezuela and one population sample of Hustedia consuta Cooper and Grant (1976b) from West Texas. In all diagrams, the upper vertical axis represents maximum width; the middle, horizontal axis represents shell length; and the lower vertical axis represents the maximum thickness. All measurements are in mm. The dashed lines indicate equidimension- ality. nificance. Stehli (1954, p. 351) hypothesized that they might represent an interlocking straining device, op- erational at the anterior margin. Cooper and Grant (1976b, p. 2761), following an informal suggestion by Stehli, demonstrated that such valve margin crenula- tions do not interlock in articulated silicified speci- mens, and in many cases leave large gaps along the commissure which would not serve well as incurrent strainers. They suggest that these internal ridges may have served as seats for attachment of marginal setae which appear to have been present in many groups of brachiopods. These striae appear to have been a rather late de- velopment in the Retziidae, appearing only in the Permian forms, and were not well-expressed until the Leonardian. Those of H. hyporhachis appear to arise at about midvalve in most cases, and to continue dis- tinctly to the anterior margin, indicating that they arose early in ontogeny. This morphological-strati- graphic relationship tends to support the Leonardian age indicated by other Palmarito biostratigraphic in- dicators. Material.— Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation 3 19 a 1 fine silicification 6 (block A) 11 2 — fine silicification 6 (block B) 2 2 _ fine silicification 6 (block C) 14 I 6 fine silicification 10 297 33 38 fine silicification 11 30 13 11 medium-grained silicification 13 81 8 7 fine silicification Hustedia sp. Plate 7, figures 37, 38 Discussion.—A single poorly preserved specimen referable to the genus Hustedia was recovered from each of localities 1 and 8. No internal details can be seen, and the surface is insufficiently preserved to al- low even a count of number of costae. The specimens are, however, of the same general size and shape as A. Plot for Hustedia hyporhachis from locality 10, Palmarito Formation (100 specimens). mature individuals of Hustedia hyporhachis n. sp., although they cannot confidently be assigned to that or any other species of the genus. Types.—Figured Specimens: USNM 221407, USNM 221408. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 ] oo — calcite permineralization 8 1 — — coarse silicification Suborder ATHYRIDIDINA Boucot, Johnson and Staton, 1964 Superfamily ATHYRIDACEA McCoy, 1844 PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 93 B. Plot for Hustedia hyporhachis from locality 13, Palmarito Formations (100 specimens). Family ATHYRIDIDAE McCoy, 1844 Subfamily ATHYRIDINAE McCoy, 1844 Genus CLEIOTHYRIDINA Buckman, 1906 Type Species.—Spirifer deroysii Leveille, 1835, p. 39 = Athyris roysii Davidson, 1860, p. 84, pl. 18, fig. 8 (by original designation of Buckman, 1906, p. 324). Diagnosis.—Athyridinae having concentric lamellae that bear short spines, ventral beak without interarea, subcircular pedicle foramen that penetrates the apex of the beak, small dental plates in the ventral interior and an apically perforate hinge plate in the dorsal in- terior. Occurrence.—Cleiothyridina occurs in rocks rang- ing in age from Late Devonian through the Permian, C. Plot for Hustedia consuta Cooper and Grant (1976b), locality 707e, Road Canyon Formation, West Texas (42 specimens: larger dot represents the dimensions of the holotype). and its distribution is cosmopolitan. In the Permian it occurs in both Austral and Boreal regions, and is com- mon in Europe and Asia. It is a rare element in West- ern Hemisphere Permian faunas, where the species are generally small and easily overlooked. Two frag- mentary specimens referable to the genus have been recovered from locality 3 in the Palmarito Formation. Comparison.—The Palmarito Formation forms of Cleiothyridina may easily be distinguished from Com- posita Brown (1849), the only other co-occurring athyridine genus, by its characteristic broad lamellar extensions, arising at the concentric growth lines, and extending anteriorly as fine solid spines. Discussion.—Cleiothyridina demonstrates one of the difficulties inherent in recognizing many of the cos- mopolitan forms in their Tethyan realm occurrences: 94 BULLETIN 313 genera which are relatively abundant and possess shells of moderate size in Boreal and Temperate realms, appear to exist at a competitive disadvantage at lower latitudes, where they are rare, small and patchily distributed. Cleiothyridina cf. C. nana Cooper and Grant Plate 8, figures 19-25 cf. Cleiothyridina nana Cooper and Grant, 1976a, p. 2136, pl. 650, figs. 36-49, 84-99. Description.—Small, small for genus, suboval to subpentagonal in outline, moderately globose in lateral aspect, biconvex; greatest width at or anterior to mid- length, commissure weakly uniplicate; fold low and rounded, sulcus shallow, limited to anterior portion of shell; concentric lamellae closely spaced, spinose, spines better preserved nearer margins, short, closely spaced; posteriorly bearing fewer and lower spines and numerous spine bases; growth laminae few and weak. Ventral valve moderately convex; beak thick, near- ly straight; foramen small, round, poorly preserved, piercing beak at apex; dorsal valve somewhat more convex, especially posteriorly, bearing small spines as on ventral valve. Interiors unknown. Measurements (in mm).— Maxi- Height Dorsal = Maxi- mum of Fold Valve mum Thick- at Com- Length Length Width ness — missure Loca.ity 3 USNM 221409 7.0 6.0 6.5. 5.0 125 Occurrence.—Cleiothyridina nana has previously been recovered only from the Road Canyon Formation (Leonardian of West Texas), where it is rare. In the Palmarito Formation it is also rare. Only a single ju- venile and a single adult specimen were recovered from locality 3. A Late Leonardian age for that locality in the Palmarito is not inconsistent with other bio- stratigraphic indicators. Diagnosis.—Very small Cleiothyridina with slightly folded anterior commissure. Types.—Figured Specimens: USNM 221409-221410; Measured Specimen: USNM 221409. Comparison.—C. nana is effectively distinguished from C. ciriacksi Cooper and Grant (1976a), C. rara Cooper and Grant (1976a), C. rectimarginata Cooper and Grant (1976a) and several undescribed species from the West Texas region by the slight uniplication of its anterior commissure. Its commissure is, how- ever, less strongly uniplicate than that of another West Texas species, C. pilularis Cooper and Grant (1976a). C. mulsa Cooper and Grant (1976a) is very weakly uniplicate, and has vestigial dental plates, compared to the robustness of those features in C. nana. The Bolivian species C. intonsa Chronic (1949) is recti- marginate. Discussion.—Cleiothyridina cf. C. nana is rare in the Palmarito Formation. The small size of this form agrees well with other Western Hemisphere Tethyan species of the genus. Its rarity in apparently autoch- thonous collections of silicified material may indicate that its life distribution was extremely discontinuous, rather than that the sampling was poor. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 3 2 _ — fine silicification Genus COMPOSITA Brown, 1849 Type Species.—Spirifer ambiguus Sowerby, 1823, p. 105, Tab. 376, 4 figs. (by original designation of © Brown, 1849, p. 131). Diagnosis.—Biconvex, streamlined narrow-hinged Athyridinae lacking interarea or beak ridges, having uniplicate commissure and proportionately large oval, epithyridid or permesothyridid pedicle foramen. Occurrence.—Composita has been reported from rocks of Devonian through Permian age. In the Perm- ian it appears to have had a world-wide Tethyan dis- tribution. Although it occurs sparingly in intermediate (“‘temperate’’) paleoclimatic zones, it has never been reported from Boreal assemblages. In the Western Hemisphere it is known from southern and central North America, northern Central America and north- — ern and central South America. Comparison.—Its longer, more erect beak, larger pedicle foramen, generally more elongate outline and lack of surface spines distinguish Composita from the other co-occurring athyridine genus Cleiothyridina Buckman (1906). The lack of beak ridges or deltidial | plates, and the type and position of the pedicle fora- — men distinguish Composita from Dielasma W. King (1859). Neophricadothyris Likharev (1934) or Marti- nia McCoy (1844) have the same sort of outline, but © may be distinguished by their trigonal delthyria and | unperforated beak apices. Discussion.—Composita, originally separated from | the genus Spirifer Sowerby (1816), is still of relatively | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 95 hoary antiquity. Although it now houses probably less than half the species originally assigned to it, due to refinement of the genus over the last hundred or more years, the number of species within the genus taxes the credulity of the average investigator. Various in- vestigators (e.g., Grinnell and Andrews, 1964; Lutz- Garihan, 1974) have demonstrated that a continuum of intergrading forms exists between several of the better-known species of Composita in North America. The artificiality of paleospecies assignment is rarely better exhibited than in Composita. The brachiopod fauna of the Palmarito Formation appears to show greatest overall similarity to forms from the Permian basins of West Texas: therefore it is among these well-studied and thoroughly investi- gated faunas that similar species of Composita are chiefly sought. Composita cf. C. pilula Cooper and Grant Plate 8, figures 26-38 cf. Composita pilula Cooper and Grant, 1976a, p. 2159, pl. 657, figs. 1-39. Description.—Small, small for genus, subtrigonal, subovate or subpentagonal in outline, commonly somewhat elongate, widest anterior to midlength; an- terior commissure weakly parasulcate; fold standing only slightly higher than flanks anteriorly, sulcus ex- pressed anteriorly only; growth laminae weak, widely spaced over most of shell; stronger, more crowded nearer margins; latest growth increments of largest specimens imbricate, forming somewhat inset, corru- gate face oriented normal to plane of commissure. Ventral valve strongly convex, radius of curvature smallest posteriorly; beak short, thick, suberect or erect; foramen small, periphery narrowly incomplete; edge of valve flanged or bearing shallow groove in most mature specimens. Dorsal valve less strongly convex, greatest height at or slightly anterior to umbo, but posterior to mid- valve; valve margins fitting flange or groove of oppo- site valve. Ventral interior having slender, sharp, posterodor- sally recurved pair of hinge teeth; dental plates thin, subparallel, free of apical walls anteriorly; muscle area shallowly impressed, pattern normal for genus. Dorsal interior having small hinge plate, with deep median notch in many specimens; cardinal process bilobate, lobes bearing small muscle attachment mark on anterodorsal faces; adductor muscle attachment area elongate, narrow, having low median dividing ridge posteriorly; crura, descending lamellae and spi- ralia not seen. Measurements (in mm).— Dorsal Maximum Total Valve Maximum _ Thick- Length Length Width ness LocaLirty 3 USNM 221411 17.7. 1523 — il. LOCALITY 4 USNM 221412 11.8 10.2 10.5 8.3 USNM 221413 13.0, 11.5, 10.0, 8.7. LOCALITY 7 USNM 221414 15.0 12.7 12.5 10.9 USNM 221415 7? 14.8 14.3. 11.8, USNM 221416 17.5 15.0 16.9 12.0 USNM 221417 18.4 Se2= 16.1 13.6 USNM 221418 21.8 18.5, 18.6 14.6, USNM 221419 22 18.8, 19.3 16.1 LocaLiTy 8 USNM 221420 5.4 4.6 522 3.0 USNM 221421 6.7 6.2 6.1 4.4 USNM 221422 7.8 6.9 7.1 5.0 USNM 221423 8.5, Use) 7.4 5153} USNM 221424 10.0. 9.056 8.1, 6.5), USNM 221425 11.9 10.5 10.0 7.9 USNM 221426 12.44. 11.7 10.4 7.6 USNM 221427 12.5. Nilez/ 10.1 8.2 USNM 221428 12.9 11.1 11.9 8.4 USNM 221429 12.9 11.2 10.6 8.2 USNM 221430 13.1 11.4 11.6 8.1 USNM 221431 13.3 11.3 10.8 8.6 USNM 221432 13.3 11.3 11.5 9.0 USNM 221433 13.5 11.9 12.4 8.4 USNM 221434 14.3). 1Sailre 11.5 G3} USNM 221435 15.8 13.6 13.0 9.7 Locatity 11 USNM 221436 16.2 13.5 13.8 10.9). USNM 221437 17.8 15.2 17. 1p. 12.2 Loca.ity 13 USNM 221438 — = sP255) 9.5 USNM 221439 14.9 13.0 11.4 9.7 Occurrence.—Composita pilula, in the West Texas region where it was first described, has been recovered only from the Road Canyon Formation (Leonardian). In the Palmarito Formation it is one of the more ubi- quitous articulate brachiopods, occurring sparingly in assemblages 1, 3, 4, 7, 10, 11 and 13 and abundantly in assemblage 8. A Late Leonardian age for all of these assemblages is not inconsistent with other biostrati- graphic indicators. Diagnosis.—Shell small, outline elongate, beak short, growth laminae strong near margins, margins commonly flanged or grooved, fold and sulcus very weak, commissure weakly parasulcate. Types.—Figured Specimens: USNM 221420, USNM 221421, USNM 221423, USNM 221425, USNM 96 BULLETIN 313 221431, USNM 221433, USNM 221435, USNM 221437, USNM 221440, USNM 221441; Measured Specimens: USNM 221411-221439. Comparison.—Composita cf. C. pilula includes ma- ture individuals of a smaller size than C. affinis Girty (1909), C. apheles Cooper and Grant (1976a), C. ap- sidata Cooper and Grant (1976a), C. cracens Cooper and Grant (1976a), C. crassa Cooper and Grant (1976a), C. emarginata Girty (1909), C. enormis Coo- per and Grant (1976a), C. grandis Cooper (1957), C. hapsida Stehli and Grant (1970), C. imbricata Cooper and Grant (1976a), C. prospera Cooper and Grant (1976a), C. stalagmium Cooper and Grant (1976a), C. strongyle Cooper and Grant (1976a), C. subtilita (Hall, 1852) and C. subtilita peruviana Chronic (1949), and of a larger size than those of C. bucculenta Cooper and Grant (1976a), C. costata Cooper and Grant (1976a), C. mexicana (Hall, 1857), C. miniscula Chronic (1949) and C. nucella Cooper and Grant (1976a). C. cf. C. pilula is generally more parasulcate than C. minuscula, C. subtilita or C. subtilita peru- viana, and less parasulcate than C. bucculenta and C. parasulcata Cooper and Grant (1976a). C. pyriformis Cooper and Grant (1976a), of the same mature size as C. cf. C. pilula, has a more distinctly trigonal outline, while C. emarginata is distinguished by its markedly emarginate anterior commissure. C. parasulcata, which occurs in the Road Canyon and younger units in the West Texas region, is very similar to C. cf. C. pilula, but, in addition to its greater degree of para- sulcation, is more distinctly transverse in outline. C. pilula of the West Texas region tends to be somewhat more globose than the Palmarito specimens tentatively referred to the species, and contains dental plates that are fused to the apical walls along their entire length, in contrast to their free-standing situation in the Ven- ezuelan specimens. Discussion.—Composita is an extremely conserva- tive genus that contains variable and intergrading species. A single specimen of Composita could rarely be identified to species: large samples of populations are required to determine such taxonomically signifi- cant parameters as size of mature individuals, modal shape, outline, and variations in the development of fold and sulcus. The numerous species erected by Cooper and Grant (1976a) contain some stratigraphic input: the Wolfcampian species C. bucculenta con- tains many individuals which would be indistinguish- able from those of C. parasulcata or C. pilula. Cer- tainly in these taxa we are dealing with distinct populations of closely related brachiopods: whether or not these populations truly represent distinct biologi- cal species has not been demonstrated to my satisfac- tion. It is for this reason that the Palmarito Composita is only tentatively assigned to C. pilula Cooper and — Grant. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation calcite permineralization fine silicification fine silicification calcite permineralization fine silicification fine silicification coarse silicification fine silicification Nw oo RaRRASNH S || oe ll Se | ee @aaS ll = all Suborder SPIRIFERIDINA Waagen, 1883 Superfamily CYRTIACEA Frederiks, 1924 Family AMBOCOELIIDAE George, 1931 Genus COSTICRURA new genus Etymology of Name.—L. costa = rib; L. crura = legs, shanks [used to connote affinity to Crurithyris George (1931)]. Description.—Unequally biconvex, commonly transverse, having ventral valve deeper than dorsal; hingeline straight, anterior and lateral margins gently rounded, cardinal extremities acute to obtuse, anterior commissure rectimarginate; ventral valve slightly flat- tened anteromesially, dorsal valve gently rounded in anterior aspect; valves costate; costae low, rounded, straight, extending from beaks to margins. Ventral valve hemipyramidal, considerably inflated, having high, ventral to apsacline interarea, high, open: delthyrium, and straight hingeline. Dorsal valve more flatly convex, low beak rarely produced posterior to hingeline. Interarea very low, dorsal to anacline, having small open notothyrium. Ventral interior without dental plates, median sep- tum or recognizable muscle attachment scars. Short simple teeth at anterior edges of delthyrium. Dorsal interior having simple paired sockets, unsup- ported by socket plates; cardinal process inset, bilo- bate, divided by relatively coarse simple median ridge. © Crural plates long, delicate, arising from posterior valve floor anterodorsal of sockets, curving gently an-_ teroventrally and mesially to about midvalve, there’ turning ventrally, closely appressed; a short distance’ anteriorly becoming flattened, broadened, recurving: laterally toward opposite valve walls, then mesially: recurved, initiating first whorl of spiralium. Type Species.—Costicrura minuta new species. ! | | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 97 Diagnosis.—Costate Ambocoeliidae, lacking fold or sulcus. Occurrence.—Costicrura has to date been re- covered only from locality 6, blocks A, B and C, in the Palmarito Formation of Venezuela. A very small “ribbed Crurithyris’’ was noticed in acid etch residues from Permian rocks of Thailand (Grant, 1975, pers. comm.), but since this was not recovered, its relation- ship to Costicrura cannot be ascertained. Comparison.—Costicrura is easily distinguished from the other Permian ambocoeliid genera Cruri- thyris George (1931) and Attenuatella Stehli (1954), by its costate ornament and lack of fold or sulcus. It is distinguished from the finely costellate genus Wilber- rya Yancey (1978), by its less globose anterior profile, its acuminate cardinal extremities, and its coarser ra- dial ornament. Discussion.—It is likely that further occurrences of Costicrura will be reported from the Permian Tethyan realm, as more studies of silicified faunas are under- taken. The extremely small size of the Palmarito species may be typical of the genus. If so, only picking of fine size fractions of acid etch residues could yield specimens of this elusive genus. The small size would, in addition, preclude recovery of these forms from fau- nas preserved by other modes than silicification. Costicrura minuta new species Plate 8, figures 39-44 Etymology of Name.—L. minuta = small. Description.—Minute, unequally biconvex, trans- verse, having straight hingeline; hinge width varying from slightly less than to slightly more than midwidth, commonly about one and one-half times as wide as long. Anterior commissure rectimarginate, lacking dis- tinct fold or sulcus; ventral valve straight-sided, flat- crested in anterior aspect, high triangular in lateral aspect; dorsal valve low, gently and broadly rounded in anterior and lateral aspects. Both valves costate; costae extending from beaks to margins. Ventral valve hemipyramidal, considerably inflated, having high, ventral to apsacline interarea, high, open triangular delthyrium, and straight hingeline. Dorsal valve shallowly convex, low beak produced slightly posterior to hingeline. Very low, dorsal to an- acline interarea having small open triangular noto- thyrium. Ventral interior without dental plates, median sep- tum or recognizable muscle attachment scars. Short simple teeth at anterior edges of delthyrium. Dorsal interior having simple paired sockets, unsup- ported by socket plates; cardinal process inset, bilo- bate, divided by relatively broad simple median ridge. Crural plates long, delicate, arising from posterior valve floor anterodorsal of sockets, curving gently an- teroventrally and mesially to about midvalve, there closely appressed, turning ventrally, a short distance anteriorly becoming flattened, broadened, recurving laterally toward opposite valve walls, then mesially recurved, initiating first whorl of spiralium. Measurements (in mm).— Total Hinge Mid- Thick- Length Width Width ness LOcALITy 6 (block A) USNM 221442 1.1 1.3, 1.6 0.9 USNM 221443 1.2 1.2, 1.7 Hee USNM 221444 1.2 1.4 1.6 1.0 USNM 221445 1.3 1.5, 1.8 1.1 USNM 221446 1.3 -7/ 1.8 1.2 USNM 221447 1.4 1.6 1.8 1.3 USNM 221448 1.4 7/7 1.9 1.2 USNM 221449 1.4 1.8 1.8 1.2 USNM 221450 1.4 1.8 1.9 1.3 USNM 221451 1.4 1:9 1.8 2 LOCALITY 6 (block B) USNM 221452 0.9 1.0, 1.3 0.8 USNM 221453 1.5 2.3 Dal 1.4 (holotype) LOCALITY 6 (block C) USNM 221454 0.7 0.7 1.0 0.5 USNM 221455 0.7 0.9 1.0 0.5 USNM 221456 0.8 1.1 12 0.6 USNM 221457 0.9 0.9 1.1 0.5, USNM 221458 1.0 1.2 1.3 0.8 USNM 221459 1.1 1.4 1.6 0.9 USNM 221460 1.1 1.5 1.6 1.0 USNM 221461 ile 115) lea 1.0 USNM 221462 12 1.6 slag 1.1 USNM 221463 1.2 1.4, 1.8 1.0 USNM 221464 1.2, 1.6, 21, 1.2, USNM 221465 1.4 1.9 1.8 1.3 USNM 221466 1.4, 2 2.0 1:25 Occurrence.—as for genus. Diagnosis.—Minute Costicrura. Types.—Holotype: USNM 221453; Figured Speci- mens: USNM 221453, USNM 221467, USNM 221468; Measured Specimens: USNM 221442-221466. Comparison.—C. minuta is the only species of the genus. Discussion.—The small ‘‘ribbed Crurithyris’’ men- tioned above, from the Permian of Thailand, if related to Costicrura minuta, probably represents a different species. It is hoped that examination of fine size frac- tions of Permian acid etch residues will yield compar- ative material. 98 BULLETIN 313 Material.— Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation 6 (block A) 13 5 7 fine silicification 6 (block B) 3 3 _ fine silicification 6 (block C) 16 14 7 fine silicification Superfamily RETICULARIACEA Waagen, 1883 Family ELYTHIDAE Frederiks, 1924 Genus NEOPHRICADOTHYRIS Likharev, 1934 Type Species.—Squamularia asiatica Chao, 1929, p. 91, pl. 11, figs. 12-14, by original designation of Likharev, 1934, pp. 211, 213. Diagnosis.—Spiriferacea having biramous spines in concentric rows and the spiral axes coiled postero- laterally. Occurrence.—Neophricadothyris is a Permian rep- resentative of a stock of elythids that range from the Lower Carboniferous through the highest stage of the Permian. In the Permian its geographic range is truly cosmopolitan. In the Palmarito Formation it has been recovered from localities 1, 7 and 8. It is rare at lo- cality 1, common at locality 8 and abundant at local- ity 7. Comparison.—Neophricadothyris differs from Squamularia Gemmellaro (1899) in its biramous spines, narrower, posteriorly directed and more nu- merous coils of spiralia, and its apparent more evenly concentric ornament. It differs from Phricadothyris George (1932), in its posterolaterally, rather than lat- erally directed spiralia. Martinothyris Minato (1953) and Nebenothyris Minato (1953) differ in having dental plates or strong median septa internally, but Maxwell (1961) has noted that both are invalid on nomenclatural grounds as well. Condrathyris Minato (1953) is appar- ently (fide Cooper and Grant, 1976a, p. 2247) a junior synonym of Phricadothyris. Pavlova (1965) studied the type species of the genus, Squamularia asiatica Chao (1929), and determined that it is not distinct from species of Phricadothyris. Permophricodothyris Pavlova (1965) was introduced to accommodate those forms, such as the Palmarito species, in which the spiral axes are directed postero- laterally. I concur with Cooper and Grant (1976a, p. 2248) in supporting the validity of Permophricodothy- ris, but have retained the name Neophricadothyris, in order that the Venezuelan and West Texas species may be less ambiguously comparable. Neophricadothyris cf. N. crassibecca Cooper and Grant Plate 8, figures 45-57 cf. Neophricadothyris crassibecca Cooper and Grant, 1976a, p. 2253, pl. 638, figs. 1-33. Description.—Small to medium-sized, average sized for genus, strongly biconvex; outline variable, sub- pentagonal to subelliptical, juveniles commonly trans- verse, mature individuals commonly more elongate; greatest width near midlength of shell; commissure rectimarginate in juveniles, becoming weakly unipli- cate in more mature individuals; fold very low, not normally expressed posterior to commissure, sulcus more prominent, shallow, arising about 10-15 mm an- terior to ventral beak; concentric lamellae moderately strong, variable in density, from four to 14 in a 5 mm distance at about midlength of mature individuals; each lamella bearing one or two rows of double-bar- relled spines; growth lamellae unevenly spaced, lo- cally crowded. Ventral valve strongly convex, greatest height pos- | terior to midvalve; beak commonly thickened, blunt, strongly curved, erect to slightly incurved; interarea curved, narrow, outlined by poorly defined beak ridges; delthyrium nearly equilaterally triangular, lat- — erally bounded by low deltidial flanges, leaving del- thyrium entirely open. Dorsal valve less strongly convex; low beak in some mature specimens partially blocking delthyrium; in- terarea flat to slightly concave, of moderate height, broken by low, broad notothyrium; low flanges bound- ing margins of notothyrium. Ventral interior having very short, pointed, slightly hooked teeth; dental ridges weak to moderately strong, united below delthyrial apex, not obstructing delthyrium; muscle area weakly to strongly impressed, elongate subelliptical to heart-shaped (in latter case bisected by very low narrow median ridge), commonly — longitudinally striate, migrating anteriorly during on- togeny; earlier, posterior traces covered by secondary callus shell material. Adductor marks commonly pres- ent, diductor marks rarely preserved. Dorsal interior having comparatively large hinge sockets, socket ridges having tooth-like swellings an- teriorly; cardinal process small, poorly defined; heli- cophores and spiralia not preserved in silicified spec- imens, but axes of coiling generally divergent toward posterior, trending from lateral toward posterior ori- entation during course of ontogeny; muscle area nar- | row, elongate, weakly striate, sides slightly divergent | anteriorly, bisected by very low, narrow median ridge. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 99 Measurements (in mm).— Maxi- Dorsal Maxi- mum Total Valve Hinge mum Thick- Length Length Width Width ness LocaLity 7 USNM 221469 10.3 8.8 8.4, 11.8 11.7 USNM 221470 11.8 10.8 9.6. 13.1 9.5 USNM 221471 13.5 11.8 8.6, 14.0 9.8 USNM 221472 15.0 13.5 10.7. 16.1 11.3 USNM 221473 15.3 13.8 10.3, 16.1 12.2 USNM 221474 16.8 15.5 10.9, 17.8 13.0 USNM 221475 16.9, 15.5, 11.1, 18.6, 11.9, USNM 221476 17.5 15.4 9.6. 18.2 V5 USNM 221477 18.7 15.8 11.8, 19.5 13.7 USNM 221478 18.8 119272 10.7. 15.5 13.0 USNM 221479 20.7 18.5 14.6, 20.8 14.6 USNM 221480 = 21.5 19.4 14.2, 21.0 14.8 USNM 221481 21.8 18.8 15.5 21.0 16.1 USNM 221482 22.0 MES 16.0, 21.9 15.8 USNM 221483 23516 19.6, 14.1, 21.0. 17.4, USNM 221484 =. 23.1 20.0 1523. 24.0 17.1 USNM 221485 24.5 19.3 11.9, 22.4 18.8 USNM 221486 26.2 21.9 16.1, 25.2 18.9 USNM 221487 26.4 22.5 16.8, 24.6 19.5 Loca.ity 8 USNM 221488 — — 14.8 21.8 17.4 USNM 221489 = 25.2 aes) 14.1 20.1 20.2. Occurrence.—In the West Texas region where it was first described N. crassibecca occurs only in the Road Canyon Formation (Late Leonardian). A very closely related species, N. bullata Cooper and Grant (1976a), has been recovered from the Bone Spring, Hess, Cathedral Mountain and Road Canyon Forma- tions, of from Late Wolfcampian to Late Leonardian age. In the Palmarito Formation individuals here ten- tatively referred to N. crassibecca but also similar to N. bullata have been recovered from localities 1, 7 and 8. An Early Permian age for the assemblages re- covered from these localities is not inconsistent with other biostratigraphic indicators. Diagnosis.—Strongly biconvex, apically thickened Neophricadothyris having variable outline and orna- ment. Types.—Figured Specimens: USNM 221469, USNM 221472, USNM 221479, USNM 221485, USNM 221487, USNM 221488-—221493; Measured Specimens: _USNM 221469221489. Comparison.—Neophricadothyris cf. N. crassibec- ca in the Palmarito Formation is an extremely variable species. It is easily distinguished from some of the West Texas species of the genus. N. catatona Cooper _ and Grant (1976a) is much larger and more transverse, while N. transversa Cooper and Grant (1976a) is more uniformly transverse throughout its ontogenetic de- velopment. Mature individuals of N. conara Cooper and Grant (1976a) are smaller than those of N. cf. N. crassibecca while similar ontogenetic stages of N. guadalupensis (Shumard, 1859) are larger, more com- monly elongate, and have a flatter dorsal valve and higher deltidial flanges and dental ridges. Squamularia guadalupensis R. E. King (1931) included individuals assignable to two distinct species, N. bullata and N. conara, and cannot thus be directly compared to N. cf. N. crassibecca. In the West Texas area, several characters serve to distinguish suites of N. bullata, N. cordata and N. crassibecca. The Venezuelan speci- mens are most similar to the West Texas N. crassi- becca, but, because they are more variable than known individuals of that species, they intergrade more extensively with other similar species. In the West Texas region, N. crassibecca is distinguished from closely related species by its small size, pentag- onal or elliptical outline, crowded concentric lamellae, each bearing but a single row of double-barrelled spines, its great biconvexity, and its thickened ventral umbonal region. In the Venezuelan specimens only the last of these characters appears to be consistently different from other known species, except N. cras- sibecca. This single feature alone is clearly insufficient for erection of a new species. N. cf. N. crassibecca differs from the Bolivian Permian Phricodothyris sep- tata Chronic (1949) in lacking a median septum in the ventral valve, and from Phricodothyris guadalupensis peruensis Chronic (1949) in the larger size of its mature individuals. Discussion.—Cooper and Grant (1976a, p. 2254) have suggested that N. crassibecca may indeed be considered a subspecies of N. bullata. It does seem very difficult to differentiate in an objective manner between the various species of Neophricadothyris that have been erected. Perhaps the feeling that organisms must evolve through time has led to the expression of specific differences where only population variation exists. If, as has been suggested (e.g., Eldredge and Gould, 1972, pp. 82 ff.) speciation does take place near the extremes of the geographic range of a species, it becomes more realistic to consider that the species bullata, crassibecca and cordata may be separable in the West Texas region, yet occur within a single pop- ulation in Venezuela. A similar situation apparently occurs in the relationship of Texan and Venezuelan species of Cooperina Termier, Termier and Pajaud (1966). Several of the Venezuelan specimens from locality 7 do not follow the common ontogenetic pattern in 100 form development. These more elongate individuals may be responding to the same sort of crowding pres- sures noted in population samples of Hustedia hypo- rhachis n. sp. from locality 10, Palmarito Formation. Certainly, equivalent positions of faunal dominance are attained by Hustedia Hall and Clarke (1893) at locality 10 and Neophricadothyris at locality 7, and to a lesser degree, at locality 8. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 1 2 — 5 calcite permineralization 7 110 11 40 calcite permineralization 8 6 U 36 fine silicification Superfamily SPIRIFERACEA W. King, 1846 Family SPIRIFERIDAE W. King, 1846 Subfamily NEOSPIRIFERINAE Waterhouse, 1968 Genus NEOSPIRIFER Frederiks, 1924 Type Species.—Spirifer fasciger Keyserling, 1846, in Keyserling and Krozenstern, p. 231, pl. 8, figs. 3- 3b (by original designation of Frederiks, 1924, p. 311). Lectotype = Spirifer fasciger Keyserling, 1846, pl. 8, fig. 3b (non figs. 3, 3a = species unknown) (by des- ignation of Cooper and Grant 1976a, p. 2173). Diagnosis.—Spiriferidae with fasciculate costae, without scaly, raised growth laminae, and with fine radial ornamentation weak or absent. Occurrence.—Neospirifer ranges through Pennsyl- vanian and Permian strata, and in the Permian has a cosmopolitan distribution. In the Palmarito Forma- tion, it has been recovered from localities 1 and 7, where it is common, and localities 4 and 8 where it is rare. Comparison.—Neospirifer is distinguished from Aperispirifer Waterhouse (1968), an Asian and Aus- tralian genus, by the absence of any delthyrial plate in juvenile or early mature stages of that form. Car- torhium Cooper and Grant (1976a) is distinguished by its more rounded flanks, consistently triangular ventral interarea, subelliptical or rarely transverse outline, and limitation of its costal bifurcations to the posterior part of the valves. Fusispirifer Waterhouse (1966) is generally far more transverse, and has much fainter, lower radial ornament, and a more massive delthyrial plate. Grantonia Brown (1953), from the Permian of Southeast Asia and Australia, is generally similar to Neospirifer but has stronger, less numerous fascicles, BULLETIN 313 and greatly thickened shells. Gypospirifer Cooper and Grant (1976a) has more numerous, finer, not distinctly fasciculate costae, and no real plications of the com- missure except the median fold itself. Lepidospirifer Cooper and Grant (1969) differs in having weaker fas- ciculation, finer costae, scaly ornamentation and a straighter beak, with the apical plate small, low, and normally fused to the floor of the valve. Spiriferinaella Frederiks (1926) differs in having non-fasciculate cos- tae. Trigonotreta Koenig (1825) bears costae which bifurcate only once, in an extremely regular fashion, in contrast to the condition of Neospirifer. Neospirifer venezuelensis (Gerth) Plate 9, figures 1-13 Spirifer cameratus Morton var. venezuelensis Gerth in Gerth and Krausel, 1931, p. 525, pl. 22, figs. 3-4 (non Spirifer venezuelensis Weisbord, 1926, p. 19, 20, pl. 4, fig. 6). Neospirifer thescelus Cooper and Grant, 1976a, p. 2189, pl. 609, figs. 30-48; pl. 610, figs. 1-38; pl. 611, figs. 1-12; pl. 612, figs. 1- 12. Description.—Large, strongly biconvex; outline ir- regularly semi-elliptical to subpentagonal or trapezoi- dal, normally widest at hinge but only slightly alate; commissure uniplicate medially, slightly undulating laterally; fastigium narrow, high anteriorly on larger shells; sulcus deep, broadly V-shaped in cross section, well-defined laterally by sharp costae. Costae strongly fasciculate, fascicles forming four to five plications on either flank of shell, progressively weaker laterally, commonly with prominent mesial costa arising at beak, subsidiary costae arising anteriorly by bifurca- tion, up to eight per fascicle, most on mesial fascicles; median costa of fastigium bifurcating near beak, con- tinuing anteriorly as dual crest, bifurcating laterally only anteriorly. Median costa of sulcus narrowly bi- furcated near beak, continuing to commissure, other costa in sulcus produced by lateral bifurcations of sul- — cus-bounding costae. Fine radial ornament absent; concentric ornament of fine, closely spaced growth lines, interrupted by stronger, irregularly spaced growth laminae, laminae becoming more frequent to- ward margins. Ventral valve strongly convex transversely and lon- gitudinally, greatest convexity posteriorly, shell thick- ened along hinge in large individuals; beak strongly _ hooked, overhanging open, triangular delthyrium; | pseudodeltidium apical or absent, rarely preserved; interarea concave, commonly faintly striate longitu- dinally, extending to cardinal extremities; edge of hinge bearing numerous short denticles, apparently serving as articulatory processes. Dorsal valve less strongly convex, produced only PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 101 slightly posterior to hinge; interarea low, slightly con- cave, but equal in width to ventral counterpart; no- tothyrium wide, low, apex bearing low, longitudinally finely striate cardinal process. Ventral interior bearing strong, but very short, knob-like, anteriorly diverging teeth, supported by thick, deep dental ridges; ridges commonly converging toward valve floor; dental plates continuous with den- tal ridges apically, diverging to intersect floor on either side of muscle attachment area, in larger shells partly obscured laterally by secondary shell growth, callus material also commonly filling apical cones. Muscle area elongate oval, commonly excavate apically, slightly elevated anteriorly in larger shells; adductor marks elongate, narrow, lightly striate longitudinally, lying along each side of low, thin median ridge; di- ductor marks large, lateral to adductors. Floor of valve along hinge pitted and pustulose in irregularly radiat- ing pattern. Pattern fading anteriorly. Dorsal interior having widely divergent, thick- walled hinge sockets, non-functional posteromesial portions roofed by thin plates. Helicophores, spiralia not observed. Muscle attachment area elongate, bi- sected by low, sharp median ridge; exterior plications strongly reflected on remainder of surface. Median sulcus (reflection of external fold) bearing narrow shal- low parallel furrows, running anteroventrally from midline toward sulcal margins. Measurements (in mm).— Dorsal Total Valve Hinge Mid-_ Thick- Length Length Width Width ness USNM 221494 S2e 46. 6956 62, 21, USNM 221495 58 45 67 pe 60 40, USNM 221499 48 37 52 55 33 (plastolectotype) USNM 221500 40 36 60, 60h 30 (plastoparalectotype) Occurrence.—In his discussion of the Palmarito Formation Gerth (in Gerth and Krausel, 1931, p. 524) stated: . . . Der Fusulinenkalk geht in kalkig-mergelige Lagen tiber, die die folgenden Fossilien geliefert haben: Spirifer cameratus Mort. var. venezuelensis Gerth Seminula argentea Shep. A fusulinid-bearing limestone occurs high in the Pal- marito Formation and has been noted both in the type section and in the reference section established by Arnold (1966). Specimens of Neospirifer venezuelen- sis from localities 1, 4, 7 and 8 in the present study cover most of the stratigraphic extent of the formation. The form described as N. thescelus Cooper and Grant (1976a), has been recovered only from the (Late Le- onardian) Road Canyon Formation of West Texas. A latest Leonardian age for the cited localities in the Palmarito Formation is not inconsistent with other biostratigraphic indicators. Diagnosis.—Large, thick Neospirifer having strong costae and prominent fascicles producing plications, wide hinge but short or absent alae, and a moderately deep sulcus. Types.—Lectotype: NHB L4453; Paralectotype: NHB L4452; Figured Specimens: USNM 221494— 221500; Measured Specimens: USNM 221494-221495, USNM 221499221500. Comparison.—N. venezuelensis is easily differen- tiated from N. cameratus (Morton in Hildreth, 1836), as a variety of which it was first described, by its much stronger ornament of both costae and fasciculate pli- cae. The average size of mature individuals of N. ven- ezuelensis is greater than that of the West Texas species N. apothescelus Cooper and Grant (1976a) and N. formulosus Cooper and Grant (1976a). It is less alate, or mucronate, than the West Texas species N. amphigyus Cooper and Grant (1976a), N. bakeri bakeri R. E. King (1931), and N. bakeri columbiarus Cooper and Grant (1976a). N. huecoensis R. E. King (1931) is less strongly uniplicate. N. mansuetus Coo- per and Grant (1976a), N. notialis Cooper and Grant (1976a), and N. placidus Cooper and Grant (1976a) share the lower, less marked radial ornament that is more characteristic of N. cameratus than of N. vene- zuelensis. N. neali Cooper and Grant (1976a) is seldom as long-hinged as is N. venezuelensis, and has a long- er, more strongly apsacline interarea. The character- istic dual crest of the fold distinguishes N. venezuelen- sis from the North American mid-Continent species N. triplicatus (Hall, 1852) and N. latus Dunbar and Condra (1932). It is effectively distinguished from Spi- riferella pseudocameratus (Girty, 1920), commonly considered a species of Neospirifer, by the pustulose surface ornament which places that form within the Brachythyrididae. Discussion.—Cooper and Grant (1976a) described the species N. thescelus, understandably having over- looked Gerth’s (in Gerth and Krausel, 1931) compar- atively obscure publication of §. cameratus var. vene- zuelensis. Although the Palmarito suite of N. venezuelensis is small, such diagnostic characters as the very strong fasciculate plicae and the dual crest of the fold demonstrate the synonymy of N. venezuelen- sis and N. thescelus. N. venezuelensis was first described on the basis of specimens provided to Gerth by the collector, Peter 102 BULLETIN 313 Christ, who published the first account (Christ, 1927) of the Palmarito Formation. The specimens (two syn- types) are part of the collections of the Basle Natur- historisches Museum. A holotype was not designated, possibly because Gerth described the form as a new variety of an existing species, rather than as a new species. To clarify future comparisons, I have here designated these as lectotype (NMB L4453) and para- lectotype (NMB 14452). The International Code of Zoological Nomenclature (ICZN, 1961, Art. 45, sect. d, part ii) clearly states that a variety or form erected before 1961, if it has inherent geographic significance, may be considered of infraspecific, rather than infra- subspecific status, and therefore available for eleva- tion to specific status when the generic designation is changed. Casts of the Swiss type specimens have been included with the present topotypic material as bases for the descriptions, and are figured here (PI. 9, figs. 8, 9). Material.— Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation 1 2 — 1 calcite permineralization 1 — 1 — internal cast 1 — — 1 external mold 4 — — 1 coarse silicification 7 4 5 12 calcite permineralization 8 1 — — fine silicification unknown* 2 — _ calcite permineralization * purchased from child at type locality of Palmarito Formation Superfamily SPIRIFERINACEA Davidson, 1884 Discussion.—According to the Treatise (Boucot et al., in Williams et al., 1965, p. H711) the Spiriferi- nacea consists of a single family including 19 genera ranging in age from Early Carboniferous to Early Ju- rassic. Only seven of these occur in the Permian. In the revision of the superfamily (Cooper and Grant, 1976b, p. 2666), the impunctate forms Odontospirifer Dunbar (1955) and Spiriferinaella Frederiks (1926) were removed on that basis. In addition, Paraspirif- erina Reed (1944) was removed from synonymy with Callispirina Cooper and Muir-Wood (1951), and re- designated a valid genus. Three new genera, Metri- olepis Cooper and Grant 1976b), Arionthia Cooper and Grant (1976b) and Scenesia Cooper and Grant (1976b), plus two others, Sarganostega Cooper and Grant (1969) and Xestotrema Cooper and Grant (1969), thus brought the total number of Permian spi- riferinacean genera to 11, which were distributed in six new families: Reticulariinidae, Crenispiriferidae, Paraspiriferinidae, Sarganostegidae, Xestotrematidae and an un-named family containing the single genus Scenesia. While this arrangement has some draw- backs (non-spinose Spiriferellina [sensu Frederiks, 1924] are included in the Reticulariinidae, of which a diagnostic character is that genera included in it bear large hollow spines on the exterior), it 1s followed here, since it results from study of faunas very similar to the Venezuelan ones, and because it is the most recent comprehensive study of its kind. Family RETICULARIINIDAE Cooper and Grant, 1976b Genus SPIRIFERELLINA Frederiks, 1924 Type Species.—Terebratulites cristatus Schlotheim, 1816, p. 16, pl. 1, figs. la—c, by original designation of Frederiks, 1924, p. 299. Diagnosis.—Typically small, transversely rounded, having flat-crested, low fastigium, few lateral plica- tions, irregularly spaced growth lines; surface smooth or having many small low pustules; cardinal process © narrow, crural plate broad, forming small apical plat- form. | Occurrence.—Spiriferellina is a nearly cosmopoli- tan Permian genus, having been recovered from both the Tethyan and Boreal realms. It has not to date been recognized in Australia or New Zealand. Comparison.—Spiriferellina is easily distinguished from the other two Permian Reticulariinidae, Reticu- lariina Frederiks (1916) and Altiplecus Stehli (1954), by the conspicuous hollow ornament spines of these genera, which are never present in species of Spirif- erellina. Discussion.—Due to an initial oversight by Fred- eriks (1924), who named Terebratulites cristatus Schlotheim (1816) as the type of the genus Spirifer- ellina, none of Schlotheim’s specimens was cited, and reference was instead made to descriptions and illus- trations by Tschernyschev (1902). Frederiks also cited a Bolivian Permian species, S$. campestris (White, 1874) Kozlowski (1914), since demonstrated (Chronic, in Newell et al., 1953; Cooper and Grant, 1976b) to belong in Reticulariina. With this confusion, Spiriferellina easily became a catch-all genus for punctate spiriferoids, often without | regard to comparison with its type species S. cristata. Campbell (1959) clarified the relationships of some spi- riferinaceans by redescribing type materials of Punc-. tospirifer North (1920), Reticulariina and Spiriferel- lina. Cooper and Grant’s (1976b, p. 2666 ff.)) separation of the former family Spiriferinidae into six, PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 103 new families, each distinguished on clear morpholog- ical grounds, is clearly a step towards a more system- atic, if not more realistic treatment of these punctate forms. Spiriferellina cf. S. hilli (Girty) Plate 8, figures 58-71; Plate 9, figures 28-29 cf. Spiriferina hilli Girty, 1909, p. 379, pl. 30, figs. 15—15b. cf. Spiriferellina hilli (Girty), Cooper and Grant, 1976b, p. 2703, pl. 704, figs. 18-25; pl. 709, figs. 18-71. Description.—Small, average sized for genus, un- equally biconvex; subovate to transversely subellip- tical in outline; hinge wide, cardinal extremities com- monly rectangular or slightly extended; commissure plicated by median fold and three to four, most com- monly three lower plications on each flank; plications separated by nearly equally wide troughs, all arising at beaks or along hingeline; median plication widening anteriorly, in lateral aspect rising slightly above more tightly curved lateral plications; crest of plication flat- tened at beak, remaining flattened toward anterior; sulcus shallow, somewhat quadrate in cross section, median trough flattened or slightly swollen to form low ridge. Surface bearing low, rarely preserved pustules between punctae; spines absent; growth laminae strong, widely and irregularly spaced, somewhat more crowded near margins. Ventral valve moderately deep; beak prominent, elongate or attenuate, apex bluntly pointed, moder- ately to strongly curved; interarea broadly triangular, apsacline, radius of curvature lessening towards apex; delthyrium triangular, apically bearing short bridge across median septum; deltidial plates not preserved. Dorsal valve less strongly convex, fastigium in lat- eral view nearly straight; beak bluntly pointed, inter- area low, wide, slightly concave; notothyrium broad- ly triangular, apex bearing narrow, ventrally striate cardinal process. Ventral interior having short, knob-like teeth; dental ridges moderately strong, tapering anteriorly, con- verging slightly toward midline of valve; dental plates short, apical in adults, meeting dental ridges at about one-half their length; median septum high, very thin, abruptly sloping anteriorly, extending about one-third to one-fourth valve length from apex. Muscle marks on floor of valve and sides of septum insufficiently well-preserved to distinguish adductors or diductors. Dorsal interior having wide, open sockets, partially roofed posteriorly by anterior edge of interarea; socket ridges thick, slightly elevated anteriorly; hinge plates attached to socket ridges, strongly deflected dorsally, converging and fusing along midline to form concave hinge plate, bisected by cardinal process ventropos- teriorly, markedly notched anterodorsally; crura ex- tending anteriorly from hinge plates, bowed outward, then converging; jugal processes and spiralia not ob- served. Muscle area elongate, mesial, undifferentiat- ed. Measurements (in mm).— Dorsal Total Valve Hinge Mid- Maximum Thick- Length Length Width Width Width ness Loca.ity 3 USNM 221501 2.4 2.0 2.4 2.4 1.8 USNM 221502 3.2 3:2 4.5 4.7 3.0 ~ USNM 221503 3.5 3.2 4.8, 4.8, 3.0 USNM 221504 4.0 3.8 5.4, 5.4, 32 | USNM 221505 4.5 3.9 4.9 5.4, 3.6 USNM 221506 5.3 4.7 5.6, 7.0, 4.8 | USNM 221507 6.1 5.3 _ 6.0 — 4.8 USNM 221508 7.8 6.0 3 US 8.5 3)3) USNM 221509 8.1 6.7 10.45, USS 10.44, 6.0 USNM 221510 8.0 6.3 10.3), 9.5 10.3, 2 | Occurrence.—Spiriferellina cf. S. hilli has been re- covered from locality 3 of the Palmarito Formation. S. hilli is known in the West Texas region from various localities within the Word Formation (Guadalupian). Such an age assignment is a bit younger than that in- | dicated by other biostratigraphic indicators for the Pal- marito locality, but is not beyond the realm of reason- able possibility. Diagnosis.—Transverse to nearly equidimensional wide-hinged Spiriferellina with moderately flat dorsal valve. Types.—Figured Specimens: USNM 221501, USNM 221505, USNM 221506, USNM 221508, USNM 221510—221515; Measured Specimens: USNM 221501 - 221510. Comparison.—S. hilli may easily be distinguished 104 BULLETIN 313 from S. paucicostata Cooper and Grant (1976b) by the larger size of mature individuals of that species, and from S. nuda Cooper and Grant (1976b) and S. cris- tata (Schlotheim, 1816) by the smaller size of mature individuals of those species. S. nasuta Cooper and Grant (1976b) is characterized by a markedly elongate interarea and ventral beak, while S. vescula Cooper and Grant (1976b) is much more strongly biconvex. The Late Leonardian species S$. tricosa Cooper and Grant (1976b) is very similar to S. hilli, but differs in the slightly larger size of mature individuals, its wider hinge and its more abundant pustules. The Venezuelan form here tentatively assigned to S. hilli differs from that form in West Texas in its slightly more transverse outline and its slightly higher fastigium. The outline of S. cf. S. hilli from the Palmarito is quite variable, with the hinge equal to or slightly less than the greatest width of the shell. West Texas species seem less vari- able, but whether this is ecologically caused or due to over-splitting of taxa cannot be determined. Discussion.—As in the Chonetacea, surface orna- ment is used here as an important diagnostic character at the generic level. Within any genus, specific differ- entiation is not unduly difficult. Differences at the ge- neric level however, are made less concise by the va- garies of preservation: a hollow spine, if broken off, may produce either a pustule-like prominence, a rec- ognizable hollow-spine base, or no trace; differing de- grees of decortication may produce surface punctae of differing patterns or sizes. In taxonomic determina- tions, presence of a morphologic feature is far more significant than absence. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 3 18 11 10 fine silicification Order TEREBRATULIDA Waagen, 1883 Suborder TEREBRATULIDINA Waagen, 1883 Superfamily DIELASMATACEA Schuchert, 1913 Family DIELASMATIDAE Schuchert, 1913 Subfamily DIELASMATINAE Schuchert, 1913 Genus ANEUTHELASMA Cooper and Grant, 1976b Type Species.—Aneuthelasma amygdalinum Coo- per and Grant, 1976b, p. 2906, pl. 762, figs. 26-61. Diagnosis.—Dielasmatinae without dental plates and with inner hinge plates widely separated where they meet the valve floor. Occurrence.—The genus Aneuthelasma has been reported from the West Texas region, where it occurs in the Capitan and Bell Canyon Formations (Guada- lupian). The Venezuelan form assigned to the genus is probably from a somewhat lower level. Comparison.—Aneuthelasma differs from Dielas- ma W. King (1859), Dielasmina Waagen (1882), Ec- toposia Cooper and Grant (1976b), Fletcherithyris Campbell (1965), Hoskingia Campbell (1965), Plec- telasma Cooper and Grant (1969), Whitspakia Stehli (1964) and Yochelsonia Stehli (1961a) by its total lack of dental plates in the ventral interior. Hemiptychina Waagen (1882) has an anteriorly plicate commissure, and Camarelasma Cooper and Grant (1976b) and Lowenstamia Stehli (1961b) both have inner hinge plates in the dorsal valve, features that Aneuthelasma lacks. Three genera known from the Permian of the Australia-New Zealand area [Gilledia Stehli (1961a), Maorielasma Waterhouse (1964) and Marinurnula Waterhouse (1964)], are Dielasma-like terebratuloids that also lack dental plates. These three have been combined to form the Gillediidae (Campbell, 1965), chiefly on that basis. Although Aneuthelasma and some other Dielasmatidae would logically fit in that family, I have considered it premature to relocate these genera without knowing whether hinge structure © or presence/absence of dental plates is more signifi- cant at the generic level. Of the three genera men- tioned above, Gilledia may be distinguished from Aneuthelasma by its commonly uniplicate anterior commissure; Maorielasma, like most of the Dielas- matidae, has inner hinge plates that combine to form a septalium, and Marinurnula is a much larger shell, with a distinct tendency toward folding of the anterior commissure. Internally the genera of the Labaiidae [Labaia Likharev (1956), Pseudodielasma Brill’ (1940), Oligothyrina Cooper (1956)] closely resemble Aneuthelasma. The anterior commissures of the latter two genera however are distinctly folded. The loop in’ those genera, as it arises from the crural bases, is more robust, and the two parallel elements are more closely appressed than is the case with Aneuthelasma. In ad- dition, the outer hinge plates of the Labaiidae are sec- ondary, while in Aneuthelasma they are not. Labaia itself is poorly known: though it does not appear (Li- kharev, 1956, pl. 72, fig. 3) to be folded, the interior — is not shown and has only been very broadly defined | (Stehli, 1965, p. H755). Aneuthelasma globosum new species Plate 9, figures 14—27 Etymology of Name.—L. globosus = rotund, glo-' bose. | PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 105 Description.—Small, small for genus, subtriangular to suboval to subpentagonal in outline, maximum width about midvalve. Anterior commissure rounded, straight. Valves nearly equal in depth. Surface smooth. Ventral valve evenly and moderately convex in lat- eral view; broadly and evenly convex in anterior view, with somewhat flattened flanks in older specimens. Beak short, suberect to erect; umbonal region some- what swollen, swelling absent at midvalve. Sulcus ab- sent. Foramen small, slightly labiate; beak ridges strong, rounded. Deltidial plates thin, disjunct, well- defined. Dorsal valve broadly convex in lateral and anterior views. Beak small; umbonal region narrowly swollen, anterior portion somewhat flattened. Ventral interior without dental plates, but having a well-defined, thick pedicle collar; muscle area ovate, poorly defined. Teeth short, strong, hooked slightly dorsoposteriorly. Dorsal interior having strong socket ridges and pos- terolaterally recurved fulcral plates; outer hinge plates obsolete; crural bases broad; inner hinge plates very short to absent, if present widely separated, contacting valve floor vertically. Descending branches of loop long, subparallel; transverse ribbon not observed. Measurements (in mm).— Occurrence.—Aneuthelasma globosum n. sp. has been recovered only from locality 6, blocks A, B and C, in the Palmarito Formation. The other known species of the genus, A. amygdalinum Cooper and Grant (1976b), is known from the Capitan and Bell Canyon Formations in the West Texas Permian. Diagnosis.—Small, globose Aneuthelasma. Types.—Holotype: USNM 221520; Figured Speci- mens: USNM 221516, USNM 221520, USNM 221522, USNM 221523, USNM 221526, USNM 221529, USNM 221530, USNM 221533; Measured Specimens: USNM 221516-221532. Comparison.—Aneuthelasma globosum is distin- guished from the other known species of the genus, A. amygdalinum, by its more rotund form and smaller size of mature individuals. It may be distinguished from the superficially similar form Pseudodielasma brilli Cooper and Grant (1976b) by the slight tendency of that form toward a uniplicate anterior commissure, as well as its more narrowly appressed, more robust crural bases. It differs from internally similar species of Marinurnula Waterhouse (1964) and Gilledia Stehli (1961la) in its decidedly equivalved condition and ab- sence of anterior commissural plication or folding. Discussion.—A. amgygdalinum is known only from the Early Guadalupian of the West Texas region. Al- though possible, it is unlikely, on the bases of other Palmarito biostratigraphic indicators, that A. globo- Dorsal sum is this young. Total Valve Maximum Thick- Material.— Length Length Width ness LocaLity 6 Articu- (block A) lated Dorsal Ventral Type of USNM 221516 23 20 20 14 Locality Valves Valves Valves Preservation USNM 221517 3.4, 3.1 eal 1.8 6 (block A) 12 3 3 fine silicification USNM 221518 3.9, 3.5 3.4 b6 = 6 (block B) 15 9 5 fine silicification USNM 221519 5.5, 4.7 4.5 3.1 6 (block C) 25 9 13 fine silicification USNM 221520 6.1 5.5 5.4 3.4 (holotype) LOcALity 6 (block B) USNM 221521 2.9 PLD) 23 1S, : USNM 221522 47 AR 36 29 Family PPREUDODIELASMATIDAE USNM 221523 5.1 43 3.8 355... Cooper and Grant, 1976b LOcALitTy 6 (block C) Genus OLIGOTHYRINA Cooper 1956 USNM 221524 3.0 2.6 2.5 1.6 Type Species.—Oligothyrina alleni Cooper, 1956, 99 9) >) Meise mk cit A se pe p. 526, pl. 61, figs. 33-41. USNM 221527 37 33 59 1.9, Diagnosis.—Small, with a weakly to strongly intra- USNM 221528 3.8 33 3.1 4 plicate anterior commissure; folds arising anterior to USNM 221529 4.0 3.5 3.4 DD) midlength; transverse band not projecting anteriorly. Peis 221530 4.5 4.0 3.7 2.7 Occurrence.—Oligothyrina is known from rocks 221531 4.5 3.9 3.7» 3.0 . 7 j i r fr Vv “SN a ne me iS - anging in age from Middle Pennsylvanian to Early Permian, in North America. The genus has tentatively 106 BULLETIN 313 been identified from the Chochal Limestone (Leonar- dian) of Guatemala. It is also tentatively identified at localities 3 and 13 of the Palmarito Formation, Vene- zuela. Comparison.—Oligothyrina is easily distinguished from Pseudodielasma Brill (1940) by the paraplicate anterior commissure of that genus, and from Pleure- lasma Cooper and Grant (1976b) by the costate ante- rior commissure of that genus, as compared to the intraplicate commissure characteristic of Oligothyri- na. Discussion.—Oligothyrina has not been recognized in the West Texas region. This is peculiar as few gen- era present in the Palmarito Formation are neither ‘‘West Texas’’ genera nor new. Its absence there may in some manner be facies-related, though no hard data either support or negate that suggestion. Oligothyrina? sp. Plate 10, figures 1-4 cf. Oligothyrina? sp. Stehli and Grant, 1970, p. 34, pl. 12, figs. 1- 12; pl. 13, figs. 8-16. Description.—Small, slightly small for genus, strongly biconvex, teardrop-shaped in outline; beak erect to slightly incurved; foramen somewhat telate; anterior commissure intraplicate to antiplicate; ante- rior face somewhat truncate. Surface smooth. Ventral valve evenly convex, greatest depth about midvalve; median portion of shell somewhat flattened from about midvalve anteriorly. Dorsal valve unevenly convex, greatest depth um- bonal; beak small, narrow, not protruding much be- yond outline of remainder of valve. Interiors unknown. Measurements (in mm).— Dorsal Total Valve Maximum Thick- Length Length Width ness LocaLity 3 USNM 221534 3.0 Des Del 1.8 USNM 221535 3.8 3.2 2.8 2.4 USNM 221536 4.1 3.6 3.0 3.1 USNM 221537 4.2 3.4 3.3 3.0 USNM 221538 4.4 3.6 3.0 2.9 Loca.Liry 13 USNM 221539 4.4 3.4 3.2 aH USNM 221540 4.6 3.5 3.5 3.5 Occurrence.—Oligothyrina? sp. is here reported from localities 3 and 13, of the Palmarito Formation, Venezuela. Another terebratulid, larger than the Pal- marito specimens, but also assigned tentatively to the genus Oligothyrina was reported from the Chochal Limestone, of Leonardian-equivalent age, of Guate- mala (Stehli and Grant, 1970, p. 34). The type species of the genus, O. alleni Cooper (1956), is known only from North America, where it occurs in Pennsylvanian strata. Diagnosis.—Small, strongly biconvex Oligothyri- na?, with width commonly equal to thickness. Types.—Figured Specimen: USNM 221539; Mea- sured Specimens: USNM 221534—221540. Comparison.—Since the interior of the Venezuelan form is entirely unknown, it cannot be directly com- pared to such details in known species of Oligothyri- na. It is, however, more strongly convex than either O. alleni or O.? sp. Stehli and Grant (1970), and is smaller than the latter form. Discussion.—While the interior details of the Ter- ebratulida are of great recognized importance in taxo- nomic differentiation of that group, some distinctions can nevertheless be made on the basis of external characteristics, especially in the case of the distinctive commissural folding of Oligothyrina. Material.— Articu- Local- lated Dorsal Ventral Type of ity Valves Valves Valves Preservation 3 34 — — coarse silicification 13 2 —_— = coarse silicification Suborder TEREBRATELLIDINA Muir-Wood, 1955 Superfamily CRYPTONELLACEA Thomson, 1926 Family CRYPTONELLIDAE Thomson, 1926 Subfamily CRYPTACANTHIINAE Stehli, 1965 ANAPTYCHIUS new genus Etymology of Name.—Gr. ana = not; Gr. pty- chios = folded. Description.—Small, subtriangular to subovate to subpentagonal in outline, having broadly convex ven- tral and dorsal valves; anterior commissure rectimar- ginate, unfolded; shell gently rounded in lateral and PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER anterior views; beak suberect; umbonal region flat- tened, broad in dorsal view, thin in lateral view; beak ridges distinct, strong, rounded; foramen commonly open, not labiate, rarely closed by thin disjunct deltid- ial plates anteriorly in larger shells; surface smooth. Ventral valve evenly convex, teardrop-shaped in dorsal view; greatest depth commonly at midvalve; greatest width commonly anterior thereto; foramen submesothyridid; umbonal region distinctly swollen in dorsal aspect; flattened in lateral view. Dorsal valve evenly but more flatly convex than ventral, without fold or commissural flexure; valve subcircular in outline; outline broken by narrow, short beak, beak protruding short distance into delthyrium; greatest width and depth about midvalve. Ventral interior having pair of small, blunt hinge teeth; edges of delthyrium supported by strong dental plates; muscle attachment areas posterior, elongate, poorly differentiated, divided by low broad median rise; valve floor in larger specimens thickened between dental plates. Dorsal interior having low outer hinge plates; inner hinge plates apparently disjunct in immature speci- mens, in mature specimens conjunct, slightly raised mesially and anteriorly, with small elongate apical per- foration; outer socket ridges obsolete; inner socket ridges high, thin, flared distally; hinge plate free of valve floor; median septum absent; muscle attachment areas elongate, poorly differentiated, separated by low, indistinct median rise; loop long, cryptacanthi- form, anteriorly spinose, with descending lamellae joined distally by mesially recurved jugum in immature specimens, but free in mature specimens; ascending lamellae bearing broad bands. Type Species.—Anaptychius minutus n. sp. Diagnosis.—Small, rectimarginate, unfolded Crypt- acanthiinae. Occurrence.—Anaptychius is known only from lo- cality 6, blocks A, B and C, of the Palmarito Forma- tion. Comparison.—Anaptychius is distinguished from Cryptacanthia White and St. John (1867) and Gacina Stehli (1961b) by its rectimarginate, unfolded shell, and from Glossothyropsis Girty (1934) by that feature and its lack of a dorsal median septum. Discussion.—The loop and hinge of Anaptychius unequivocally link it with the Cryptacanthiinae. I de- cided to expand the bounds of that subfamily to re- ceive unfolded shells, rather than to erect a new subfamily. The small size of this shell may in part account for its previous obscurity. 107 Anaptychius minutus new species Plate 10, figures 5—17 Etymology of Name.—L. minutus = minute. Description.—Minute to small, small for genus, sub- triangular to subovate to subpentagonal in outline, having broadly convex ventral and dorsal valves; an- terior commissure rectimarginate, unfolded; shell gently rounded in lateral and anterior views; beak sub- erect; umbonal region flattened, broad in dorsal view, thin in lateral view; beak ridges distinct, strong, rounded; foramen commonly open, but partially closed by thin, disjunct deltidial plates in larger spec- imens; surface smooth. Ventral valve evenly convex, teardrop-shaped in dorsal view; greatest depth commonly at midvalve; greatest width commonly anterior thereto; foramen submesothyridid; umbonal region distinctly swollen in dorsal aspect; flattened in lateral view. Dorsal valve evenly but more flatly convex than ventral, without fold or commissural flexure; valve subcircular in outline; outline broken by narrow, short beak, beak protruding short distance into delthyrium; greatest width and depth about midvalve. Ventral interior having pair of small, blunt hinge teeth; edges of delthyrium supported by strong, ven- trally slightly convergent dental plates; muscle attach- ment areas posterior, elongate, poorly differentiated, divided by low, broad median rise; valve floor between dental plates thickened secondarily in larger speci- mens. Dorsal interior having low outer hinge plates; inner hinge plates apparently disjunct in immature speci- mens, in mature specimens conjunct, slightly raised mesially and anteriorly, with small elongate apical per- foration; outer socket ridges obsolete; inner socket ridges high, thin, flared distally; hinge plate free of valve floor; median septum absent; muscle attachment areas elongate, poorly differentiated, separated by low, indistinct median rise; loop long, cryptacanthi- form, anteriorly bearing two or three sharp narrow anteriorly-directed spines on each bout of junction be- tween descending and ascending lamellae; descending lamellae diverging slightly from bases, bearing dorsal cuspate points, joined in young mature specimens by posteromesially cuspate jugum, jugum apparently re- sorbed in mature individuals; descending lamellae closely appressed anteriorly near junction with as- cending lamellae; ascending lamellae diverging dor- soposteriorly, broadening, curving around to join as slightly inclined broad transverse band at midline. 108 Measurements (in mm).— Dorsal Total Valve Maximum _ Thick- Length Length Width ness LOCALITY 6 (block A) USNM 221541 1.8 1s) ied 0.9 USNM 221542 2.0 1.6 1.8 0.8 USNM 221543 2.3» 1.9 73511 1.0 USNM 221544 23s 2.0 2.0 1.0 USNM 221545 the 2.3 2.5 1.4 USNM 221546 2.8 23 2.6 1.5 USNM 221547 2.8» 2.4 2.6 1155) USNM 221548 4.8 3}. 4.3 2.4 LOCALITY 6 (block C) USNM 221549 4.1) 3.5 3.1 2.1 USNM 221550 4.8 4.1 4.0 2.5 USNM 221551 4.9 4.1 4.0 25 USNM 221552 6.5 5.6 Sk7/ 3.4 (holotype) Occurrence.—Anaptychius minutus n. sp. is known only from locality 6, blocks A, B and C of the Pal- marito Formation. Based on other biostratigraphic in- dicators, this horizon contains a fauna of latest Leo- nardian to Early Guadalupian equivalent age. Diagnosis.—Small Anaptychius. Types.—Holotype: USNM 221552; Figured Speci- mens: USNM 221550—221554; Measured Specimens: USNM 221541-221552. Comparison.—Anaptychius minutus is the only species of the genus. It is differentiated from other Cryptacanthiinae chiefly by its rectimarginate, unfold- ed commissure and secondarily by its lack of a median septum. Its small to minute size suggests that it may be a small species of the genus. Discussion.—Externally Anaptychius minutus is very similar to such forms as Dielasmella Weller (1911), a Mississippian cryptonellid. Internally, how- ever, its hinge and loop clearly demonstrate its cryp- tacanthine affiliation. Material.— Articu- lated Dorsal Ventral Type of Locality Valves Valves Valves Preservation 6 (block A) 18 6 5 fine silicification 6 (block B) 2 4 4 fine silicification 6 (block C) 17 4 3 fine silicification Subfamily CRYPTONELLINAE Thomson, 1926 Genus TEXARINA Cooper and Grant, 1970 Type Species.—Texasia oblongata Cooper and Grant, 1969, p. 17, pl. 5, figs. 7-9. BULLETIN 313 Diagnosis.—Elongate, slender sulciplicate Crypto- nellacea. Occurrence.—Texarina has to date been reported only from the West Texas region, in rocks ranging in age from Leonardian (Cathedral Mountain and Road Canyon Formations) to Guadalupian (Cherry Canyon and Word Formations). An exact external homeo- morph, Mimaria Cooper and Grant (1976b) (Hetere- lasminidae) is known from the Sosio Formation of Sic- ily. It differs from Texarina in having a short loop, no dental plates and no hinge plate. Comparison.—Texarina may be distinguished from Cryptonella Hall (1861), in anterior view, by its more broadly triangular outline, which is somewhat concave ventrally, in contrast to the narrow transverse-ellipti- cal outline characteristic of Cryptonella. The ventral valve of Cryptonella is rarely so strongly sulcate as that of Texarina. Heterelasma Girty (1909) and Tex- arina are very similar. The beak of Heterelasma tends to be more incurved, and the anterior folding is com- monly better expressed in Texarina, though it is pres- ent as well in Heterelasma. Discussion.—The rare Palmarito specimens are as- signed tentatively to the genus Texarina not so much on the basis of their generic characters, but rather be- cause they are most similar to a species of Texarina. Texarina? cf. T. wordensis (R. E. King) Plate 10, figures 18-29 cf. Dielasma problematicum wordense R. E. King, 1931, p. 131, pl. 44, figs. 16a-e. cf. Texarina wordensis (R. E. King), Cooper and Grant, 1976b, p. 2836, pl. 771, figs. 1, 2; pl. 773, figs. 21-42; pl. 774, figs. 1-56; pl. 775, figs. 55-60. Description.—Medium-sized, about average-sized for genus, longer than wide; subtrigonal to elongate rhomboid in outline, becoming more elongate through ontogeny; greatest width variable, but commonly in anterior third of shell in young, near midlength in ma- ture individuals; sides broadly rounded at maximum width; anterior margin narrow, only slightly truncated in lateral view. Anterior commissure broadly unipli- cate in young, sharply sulciplicate in adult shells. Sur- face smooth except for anterior shell flexures. Ventral valve broadly convex in lateral view, great- — est convexity posterior; anterior profile moderately to deeply concave, with sides elevated and narrowly rounded, forming short, steep slopes. Beak suberect to erect, beak ridges sharp; foramen small. Umbonal | region moderately convex. Sulcus very low, arising on | anterior slope of umbonal region, broadening ante- riorly. Anterior commissure emarginate, sulcus there bearing low costa in adults. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 109 Dorsal valve of adults evenly, gently convex in lat- eral view, more convex posteriorly in immature spec- imens; in anterior view narrowly domed and with a subcarinate keel; lateral slopes steep. Median region broadly keeled from umbo nearly to anterior margin, where shallow median sulcus developed, sulcus bounded by strong rounded costae. Interiors unknown. Measurements (in mm).— Dorsal Total Valve Maximum Thick- Length Length Width ness Locatirty 11 USNM 221555 9.6, 8.6 7.0 4.6 USNM 221556 20.0 18.5 10.8 9.5 Occurrence.—Texarina wordensis occurs in the Ca- thedral Mountain and Road Canyon Formations of West Texas. In the Palmarito Formation the speci- mens tentatively referred to the species have been re- covered only from locality 11, where they are a rare faunal element. A Late Leonardian age, based on this occurrence, is not inconsistent with other biostrati- graphic indicators in assemblage 11. Diagnosis.—Narrow, moderately thick Texarina having subtruncate anterior margin and subcarinate dorsal valve. Types.—Figured and Measured Specimens: USNM 221555—221556. Comparison.—Texarina wordensis may easily be distinguished from T. oblongata (Cooper and Grant, 1969) by the larger size of mature individuals of that species, and from 7. paucula Cooper and Grant (1976b) and T. solita Cooper and Grant (1976b) by the smaller size of mature individuals of those species. T. elongata Cooper and Grant (1976b) is much deeper and in lateral view has a distinctly truncate anterior margin. 7. parallela Cooper and Grant (1976b) shares these characteristics with T. elongata, but has nearly parallel sides that do not narrow appreciably anterior- ly. In anterior view, the Palmarito specimens differ from T. wordensis in their somewhat narrower outline and less marked ventral sulcus. Discussion.—The Palmarito specimens are tenta- tively assigned to Texarina since they more closely resemble a species of that genus than species of other elongate sulciplicate terebratulid genera. Comparisons are made to the West Texas form Texarina, rather than its external homeomorph Mimaria Cooper and Grant (1976b), since the latter is geographically far distant from Venezuela, lessening the probability that it and the Palmarito specimens could be closely relat- ed. 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Dorsal valve, USNM 220975; 1. exterior view, x1; 2. interior view, x1; 3. exterior view showing smooth exterior surface, x5; 4. interior view, showing well-impressed muscle scars, x5; 5. lateral view, showing asymmetrical profile, 4; locality 6 (block A). 6. Articulated valves, USNM 220979. ventral view, showing valve overlap, x4; locality 6 (block A). AN GOSAN UMN? 'S Ps Oe eye fake lovee care feeah spate Suey serena cere er sis 270.0) clapeue¥elteve/ ates opere fepeyVeNc) RES eae eck ot = Vateh Pie ieks gale oteke thee kee aa eee 40 Ventral valve, USNM 220981; 7. interior view, showing development of dental plates and median septum, <1; 8. same view, showing disposition of teeth, x2; 9. posterior view, showing narrow delthyrium and small triangular teeth, x2; locality 7. Derbyia civ DsicomplicataiGCooperiand Grants cyege oteyesesatoter 10/21 ose = cavaveveieteceretatere re) ole as=eletarererore vey sled sey tare afetalegayev ate) ole= toe tetee ee ete aa 43 10-12. Articulated valves, USNM 220988; 10. posterior view, showing low dorsal interarea and well-developed chilidium, x1; 11. dorsal view, showing distinct sulcus and characteristic surface ornament of alternating crenulate costae and costellae, x1; 12. ventral view, showing low fold and characteristic surface ornament, 1; locality 8. 13-15. Single dorsal valve, USNM 220986; 13. ventral (interior) view, showing broadly divergent erismata, shallowly bifurcate cardinal process myophore and internal reflection of exterior surface ornament, x1; 14. posteroventral (interior) view, showing relation of cardinal process to hingeline and development of hinge sockets, x1; 15. posterior view, showing development of chilidium, 2; locality 4. 16. Fragment of ventral valve, USNM 220987; interior view, showing short median septum, faintly impressed muscle attachment scars, and interior reflection of exterior surface ornament, x2; locality 8. Derbyia/deltauriculataimi:Sps | 2f5s)< 5 seers w:cicscctercteteve setts etese se seca oveysusisle ye eyo) obelole euaye ese siete eyo eletels stata e)e eee 44 17-19. Single dorsal valve, USNM 220991; 17. ventral (interior) view, showing moderately well-impressed adductor muscle attachment scars, distally sinuous erismata, and large deltoid ears, x1; 18. posteroventral (interior) view, showing relation of cardinal process to hingeline, and development of hinge sockets, x1; 19. posterior view, showing swollen valve and development of chilidium, x1; locality 10. 20. Dorsal valve, USNM 220990; dorsal view, showing large deltoid ears, characteristic subdued surface ornament and low cardinal process, x1; locality 10. 21-22. Articulated valves, USNM 220994; 21. posterodorsolateral view, showing relation between the two valves, x1; 22. ventral view, showing horn coral (possible symbiont) attached to ventral valve, in position to intercept inferred in- current flow (lateral portion obscured by photographic mounting medium), x1; locality 10. 23. Ventral valve, USNM 220995; dorsal (interior) view, showing deflection of anterior margin and asymmetric interarea, produced by growth in crowded conditions, x1; locality 10. 24. Ventral valve, USNM 220996; posterior view, showing asymmetry produced by growth in crowded conditions, x1; locality 10. 25-26. Ventral valve, USNM 220989; 25. posterior view, showing actual size, <1; 26. posterior view, showing low interarea and mesially grooved pseudodeltidium, x2; locality 10. 27-28. Single ventral valve, USNM 220993 (holotype); 27. dorsal (interior) view, showing long median septum and well- impressed adductor muscle attachment scars, <1; 28. ventral view, showing large deltoid ears and characteristic subdued surface ornament, x1; locality 10. Derby iia pee tarecacc ices atesesstein te teucvee cre em catauch c e0Sed este ace ol asin av ge aa) Olas Pye an beats nanlenetofat chet eter oneaete opete ein at nests saree on 46 Portion of ventral valve, USNM 221002; ventral (exterior) view, showing characteristic surface ornament, x3; locality 6 (block C) Derbyiatauriplexasn. Sp. cccsve:eisse1o.2chcyod= sevens Ve aves he seh och eve ceifev ofa soledes ol sVee deteuetoheushel ol Selere oa ploneteterenelatctexeraterets fst) stet-eaee Te ee ee 42 30. Fragmentary ventral valve, USNM 220984; interior view, showing internal reflection of exterior ornament, adductor muscle scars and marginal setal grooves, <1; locality 13. 31-34. Single dorsal valve, USNM 220983; 31. posteroventrolateral view, showing cardinal process, socket development and auriculation of hinge (anterolateral portion of valve obscured by photographic mounting medium), <1; 32. posterior view, showing valve profile and relation of cardinal process myophore to erismata, x1; 33. ventral view, showing adductor muscle marks, erismata, dentifers, and strongly cleft cardinal process myophore, <1; 34. exterior view, show- ing irregular surface ornament and auriculation of hinge, <1; locality 13. 35-36. Articulated valves, USNM 220982 (holotype); 35. anterior (interior) view, showing juxtaposition of cardinal process and dental ridges (dorsal side down), * 1.5; 36. posterior view, showing ungrooved pseudodeltidium and distinct dorsal sulcus, *1.5; locality 13. BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE | BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 2 Figure PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 119 EXPLANATION OF PLATE 2 iO, Deity Gs.WDs fits Coogee andl Grint sossooascsnnonseno0 pboooUoUMooUDOUHoDuCdooNnabcoodGHoodboDHaDoDUSDHDSouoeoSood0S 1-2. ies) Apical fragment of large dorsal valve, USNM 221001; 1. posterior view, showing development of hinge sockets and relationship of cardinal process to hinge, <1; 2. ventral (interior) view, showing development of erismata and dentifers, deeply cleft cardinal process myophore, and faintly striate adductor muscle attachment scars, <1; locality 11. Apical portion of ventral valve, USNM 220999; anteroventral view, showing the paired fossae located at the junction of median septum and dental ridges, < 1.5; locality 11. Articulated valves, USNM 221000; 4. posterior view, showing relationship between dorsal valve and ventral interarea, x1; 5. anterior (interior) view, showing relationship of juxtaposed cardinal process and dental ridges, x1; locality 11. Partial ventral valve, USNM 220998; ventral view, showing large size, fine ornament of costellae, and the irregular bumpy texture characteristic of larger valves, 1; locality 11. etm VICCKENAiSK MOINES! GT, | ve fete isis evel cvsv eve) orsecete 1619 Syeye1 6 6 ele cep creer o1OIeySueneteh e tayersici@) elevsyaleie « sreifeese)s) eiestschsteuel cele) o cusiels) <)etvowi stelle eheisi evmrereselesfevedove 7-9. 10. IE 2 13-15. 16. Three sets of articulated valves, USNM 221003, USNM 221004, and USNM 221005; posterodorsolateral views of simulated partial ontogenetic series, showing differential growth of the two valves, all x1; locality 3. Ventral valve, USNM 221011; dorsal (interior) view, showing relationship of teeth, dental ridges and dental plates, and internal fold corresponding to pseudodeltidial monticulus, 1.5; locality 3. Partial ventral valve, USNM 221008; posterior view, showing pseudodeltidium bearing monticulus, and sharp teeth, 2; locality 3. Dorsal valve, USNM 221007; dorsal (exterior) view, showing costae superposed on fine costellae, x1; locality 4. Single dorsal valve, USNM 221010; 13. ventral (interior) view, showing long cardinal process and dentifers, and com- paratively short erismata, x2; 14. posterior view, dorsal side down, showing broad dentifers, elongate, longitudinally- slit myophore with shallow median cleft and apparent lack of chilidium, x2; 15. posteroventrolateral view, showing development of cardinal process and dentifers, and relationship of hinge socket to hinge, 2; locality 3. Articulated valves, USNM 221009; anterior (interior) view, showing juxtaposition of cardinal process and dental plates, x2; locality 3. INE) OMY OLOSTACANICHOPELIXGINES Dancap rer acrerey aie sheerreyeve oh ve esses ssuel eT areyey syed ave anal ty chedan ses vey tepaver axe topsteaneueaeredeney oe irae Zoueetien en cdevopee lel ievens ses) mhahscetene toredee 17-20. 21-22. Four sets of articulated valves, USNM 221012, USNM 221019, USNM 221025 (holotype), and USNM 221031; ventral views, showing range of variation in size and outline of a simulated partial ontogenetic series, all <1 (photographed in transmitted light, immersed in glycerine); locality 2. Two sets of articulated valves, USNM 221025 (holotype) and USNM 221031; 21. ventral (exterior) view, showing smaller, somewhat inset dorsal valve and oblique spine bases along hingeline; 22. ventral (exterior) view, showing shadows of endospines on tips of anderidia and anterior end of median septum, as well as anterior endospinose fringe, both x2; locality 2. Dorsal valve, USNM 221035; ventral (interior) view, showing comparatively insignificant development of anderidia and anterior endospinose fringes in an inferred early ontogenetic stage, <2; locality 2. Fragmental ventral valve, USNM 221034; dorsal (interior) view, showing anteriorly endospinose median septum and large endospines fringing the adductor muscle attachment areas, <2; locality 2. Articulated valves, USNM 221026; posterior (exterior) view, showing hood-like crescentic pseudodeltidium and multi- lobate cardinal process, x2; locality 2. Partial dorsal valve, USNM 221033; ventral (interior) view, showing long median septum, short lateral septa, strong, anteriorly endospinose anderidia and anterolateral endospinose fringes, <2; locality 2. oo? Chonetinetes cf... varians Cooper and Grant cc i5- 20s cw cies ce bloc cic ee visitie » s visiel sisi esis winvele Gitiq cles sees 6s) ae Weise eine aiwies« 27-30. 33-34. 35-36. 37. Articulated valves, USNM 221048; 27. dorsal (exterior) view, showing size and outline of typical shell, x1; 28. same view, showing radial ornament, hinge spine bases and surficial pits, x2; 29. ventral (exterior) view, showing radial ornament, surficial pits and lack of a distinct median sulcus, x2; 30. anterior view, showing lack of a distinct median fold or sulcus, x2; locality 8. Dorsal valve, USNM 221056; ventral (interior) view, showing long, anteriorly endospinose median septum, anteriorly endospinose anderidia and radial rows of minute endospines, x2; locality 8. Ventral valve, USNM 221051; dorsal (interior) view, showing comparatively large teeth, long median septum and interior endospines, <2; locality 8. eo mOtauromata,eSOterican PENANG SP: cise ar. cageys an crewsncne) sce Gyateibis wih cferniee micave tow slew are ene eyarerere he eeeeatevel Me eMe ene esi eh eke ele sla aha evesenerele © Articulated valves, USNM 221040 (holotype); 33. ventral view, showing valve outline and surface ornament, x1; 34. dorsal view, showing size and outline of shell, x1; locality 7. Articulated valves, USNM 221039. 35. lateral view, showing sinuous curvature of commissure; 36. posterior view, show- ing interareas with hood-like crescentic pseudodeltidium and multilobate cardinal process myophore; both x2; locality 7. Apical portion of dorsal valve, USNM 221043; ventral (interior) view, showing bases of lateral septa, anderidia and median septum, and apparent dendritic adductor muscle attachment scars, x2; locality 7. 47 50 54 120 Figure 1—25- Stauromata esoterica n. gen. and sp. BULLETIN 313 EXPLANATION OF PLATE 3 1-20. Serial peels of a single set of articulated valves, USNM 221045; sections parallel to plane of commissure, x2; 21-25. locality 7. Distance between successive peels as follows: 1-2 0.10 mm 2-3 0.20 mm 344 0.15 mm 4-5 0.15 mm 5-6 0.15 mm 6-7 0.15 mm 7-8 0.15 mm 8-9 0.15 mm 9-10 0.10 mm 10-11 11-12 12-13 13-14 14-15 15-16 16-17 17-18 18-19 19-20 0.20 mm 0.15 mm 0.15 mm 0.15 mm 0.15 mm 0.15 mm 0.45 mm 0.15 mm 0.45 mm 0.15 mm Schematic reconstructions (as stereopairs) of separated valves of USNM 221045, based on projections of the peels; all «4. 21-22. Dorsal valve interior, seen from within, showing the prominent endospinose median ridge, anterior endospinose fringes and distally spinose anderidia. 22-23. Dorsal valve interior, seen through the [transparent] valve from the exterior, showing the relationship of the distal ends of the anderidia and the anteriorly placed ventral valve endospinose palisades (arrow). 24-25. Ventral valve interior, showing the position of the endospinose palisades (cf. Pl. 4, figs. 1, 2). BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 3 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 PLATE 4 i Figure iA ee 3-18. 19-37. 38-39. 40-45. PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 121 EXPLANATION OF PLATE 4 Page Stauromata esotericarn agen canGeSp!,. . BULLETINS OF AMERICAN PALEONTOLOGY PLATE 10 BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 80 Figure 1-4. 18-29. Texarina? cf. T. wordensis (R. E. King) PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 127 EXPLANATION OF PLATE 10 Page CHINA Gas, coornecroscacodotosebpaccS noo ee Gmoodo OD ODOSOUSE COED ROODO OOO OOH beHOOOEGODAeOOUGOGUOeSECOOOboDDEAue 106 Articulated valves, USNM 221539; 1. dorsal view, showing size of a large specimen, x1; 2. dorsal view, showing broad ventral beak and narrow outline, <3; 3. lateral view, showing short beak and globose profile, x3; 4. anterior view, showing globose profile and intraplicate commissure, <3; locality 13. STENTS MIMICS Th, EE BOGE, coceanseoconbenopuMbooooec noccoh oo SoD bacdodondoaDcoCUDDDDODAUODDUA OOS OEONODGOOLOOC 5-10. Portion of articulated valves, USNM 221552 (holotype); 5. dorsal view, showing size and form of a large specimen, x1; 6. dorsal view, showing subtrigonal outline, rounded commissure and telate foramen, <3; 7. ventral view, showing subtrigonal outline, <3; 8. lateral view, showing unequally biconvex lateral profile and short, incurved beak, x3; 9. posterior view, showing telate foramen located in plane of commissure, 3; 10. anterior view, showing rectimarginate commissure, <3; locality 6. 11. Portion of dorsal valve, USNM 221553; ventral (interior) view, showing complete, apically perforate hinge plate and origins of loop, <6; locality 6. 12-13. Portion of dorsal valve, USNM 221551; 12. ventral view, showing hinge sockets and distally broken long loop; 13. ventrolateral view, showing long loop of apparent early ontogenetic stage, with posteroventral flanges, anterior spinose projections and anteromedian dorsal transverse band (see shadow); both x8; locality 6. 14-16. Fragment of articulated valves, USNM 221550; 14. posteroventrolateral view, showing virtually complete long loop of apparent mature ontogenetic stage; 15. ventral view, showing relationship between hinge plate and loop; 16. oblique anterior view, showing relationship between loop and ventral valve articulatory structures, including dental plates; all x8; locality 6. 17. Fragment of articulated valves, USNM 221554; lateral view, showing apparent late ontogenetic stage, and long loop without transverse band, x8; locality 6. 18-23. Articulated valves, USNM 221555; 18. dorsal view, showing size and outline of apparent juvenile ontogenetic stage, x1; 19. dorsal view, showing smoothly rounded fold of dorsal valve, x2; 20. ventral view, showing pronounced ventral sulcus, x2; 21. anterior view, showing trigonal profile and pronounced ventral sulcus, x2; 22. posterior view, showing short (?broken) beak and striking trigonal outline, x2; 23. lateral view, showing curved commissure and characteristic unequally biconvex profile, 2; locality 11. 24-29. Articulated valves, USNM 221556; 24. dorsal view, showing size and outline of apparent mature ontogenetic stage, x 1; 25. dorsal view, showing strikingly elongate, narrow outline and anterior asymmetric folding of commissure, 1.5; 26. ventral view, showing asymmetrically folded commissure and elongate outline, x 1.5; 27. anterior view, showing asymmetric folding of commissure, 1.5; 28. posterior view, showing low, short (?broken) beak and unequally biconvex profile, «1.5; 29. lateral view, showing elongate, unequally biconvex profile, «1.5; locality 11. 128 BULLETIN 313 INDEX Note: Page numbers are in light face, plate numbers are in bold face type; numbers in italics indicate principal discussions. Gages, Lophophyllidivim ........0-c1ccecceveevceneceneceecnesencce een eeeeenseeeneneene 20 DANG GAIOIA Sl Decoconcran: caeeeecbosaeneuco-oncerncesce-perescecuannoncousnescancomses Zev743 INe oleate \MHITENINS: aooscoceesennocoonespchtecoLceeesoccentioc. Hunacsaqoccoconc cord 39 PAGHTINODECLEL (acacase seaae scence seine sesees daeestnahier =aaert ia an-mesemsie meer asenn seme 25 Sarasa oe as etre ae eene abate cas enna ae lnes= ms tntnsr-naxveacescsaee=ywescrasannnsnnnn cannes 25 MAGAN{NOPE UX OOS acces sane nne enema aennee Direaxs 2), 0; 5173s St AO: Acolosia Cooper and! Grant. «<<. .-5.n.cscceessavecnsaserasnanvevarsesseseccereneseserns 85 ACOSGriINdl COOPeM ana Ghana nescecawens- cess enavesetscmscnca-isnes=senesen 14,40,41 dorsisulcata Cooper and Grant ............--00-+0seceneeeccncecnesrcossoneeresses 40 TNC TITS ena cace go Re ROC eH SCC OLE EEE DCC SECOOE CEE CRED LEBO CALICO POSE CREDO CERES 33,35 Sp ppanngeoneuendehi obo -BECee FEEere aparece sneese rp -oberccoransr soca Weise 26,40,41, 118 PAGH ALLL ISP eee senog eee ane sce iantngenin oceape ane = a= ae rnmemn sme ielinax snares 21 MUR ERENSEXENLOSTE LE Sime seceeaccete cee nces ar eereece cael ttenameneeecteenceanecsewecas 55,56 MelarOPlossan(Gh-) wi ap lis tiommerte tear tee enecat ass ccnessaseeeanetes: Teese 29 GEQUISUIGAIUS, PUPNEMILES cerenuiecesels--aerver<0-aaemannatematcberescsenrass ess === 28 GffinisS, COMPOSUA <..-.cccs=encnnsseeeeensi===snca=seowondesetnusannlersacerae--1/eaer=s- 96 INIT. cosrosceraescecoo eon 22ceece~ so roa coc caBOOOoTNEnEnOLSosoocosnpoCcOnCHOoToBES 47,57,62 / NEGA OO E Neresesecnecsssocenscnr apace sc0cc ac aasceeseenoepeneo chee casaocoscenpocBneoae Carey Aguardiente Formation iL JNU TECHIES) Saccednedecantosoncoaccubet sence Sdontessena6sc sag JU HANG, QUIZ OV ATATIEL soncosseoatnoseqen nnbcoanocecoscacodsnncosAOSIOMHaIS 105,106 PAULOF IV TIGIUSMWICILG Geetin caer ae aee centeecee se nemcnedece seta ewot nee 5 8S AU el LEAS (Sie Nao qoer neeenrepn ch opeceoehy donors syuecceor=3209 . 102 JTS scceenseesaueso-uossecebce can-aoancosonceccacteeeoacecnn HS Alveolites 11 AIMDIBUUSS PI f Claaaseseaneece seat renee sas ... 94 americana, Collemataria . 84 American Museum of Natural History (New York City, NY. U.S.A.)...... 6 amphigyus, Neospirifer On CHEAT CAE TEVICIGORE concecencoreerecce Ce cec0cee son sooconoeS TnCoSSOsEcoOARE cceoneteo 91 amygdalinum, Aneuthelasma .. 104,105 DY NTTGRAS SOs TG a ecapscondcaqqanconeo 20a ce JAB OaCDOQESR DCO SOTaSCCoAT ER TageSEOndSOSS 28 Anaptychius n. gen. . . 5,14,25,33,35, 106,107, 10: MINUIUS N. SP... + ‘5 §,24,25,107,108, 127 / MWR OS ANE Tel! Lele bi. consonesscesatoocoonincovaossconoosgbiocoodsessnoeeccasta 8,10 andersoni, Rugatia ........... 19) Anemonaria Cooper and Grant 5,67,68,69 inflata Cooper and Grant.. can (OM sublaevis (King)............+. . 27,67,68, 69,70, 122 Anemonaria? cf. A. sublaevis (King) ..- 20,29,68,69, 122 Aneuthelasma Cooper and Grant ...... . 14,33,35,104, 105 amygdalinum Cooper and Grant ... 104,105 PIOVOSUIMENENS Dacecasaeeeteees tere §,24,25, 104,105,126 angulatus, Dyoros (Dyoros) 51 angustisulcatus, Chonetinetes 55 PAITESOPY 2 Cy teenctecaveusanseeoeteaencnss = SLO 2inornata Girty .............+-+- A son eit PPL TUAGIA US NUT ETR OD enesnteeso de enon secon sae coeeeaosnobeeascoceecec none seed 28 ANOTIAIUS; MEN OSLO QOS Ie cave svees sencinactiens suasenencesunnent seUee chee wccrerennencuents 56 Anomphalus ARSE HIQMMe MMe rand Men eGares-nessen-ceaece--2- aces -ehaachene: seems eaeeneas eas 57 FNC eC ears 5: dace Rc BEES EE Ea COnCt Gio: DUOC ACE ERDE RSE DCEE net ee cea sus scbocc que ece 57 AV gUOTO/IIC, MUOLACOVICH «. 5.sauewas estes cues sane: oases eee sseAseeee cae 17,72,77,80 AnIrOnaonigneooperiand) Grantiees-s.cccscccessontcuce ve nestacdutersoesacecresteccis 85 Apachella BUA TANCISCONAI(C MTOMNIC) fexinessrotenc ase. ct ere: seem cere secon a Ces 21,29 See Faroe ene dealer crs wsinn tor «dencanteds ines taceyssuaipdscasnstee reas emeereeect 23,29,30 SPN leecsessascccsesecees Iwan dddanducnraupancavaWs teascnvee cen teessee tere peneets 21,28 FADEFISDIFIEDIW ACELDOUSE : 505225 .aanescevcnwacisdees «os cososssdduecsaten de terete 100 PAD HAUrOsImaCOOper aNd iGrant, cacecsaecssercene ons occ cvsenes dena cerscvesactinceesenee 85 PEDHELER IG OIIPOGUG tevwnaicchadioretcescdrvddtccsuassscanaacntancatatneeteet terre 96 DUM ESLEIU ASIN EOSDIFUEl. aaccducacecesccugssancsatcaqncxtossecsante ties e mae 101 PeOPAMCMIAMLSeCOSVNCINAl DELL ci.t cp-cecssreostusscaciscactncceserccstnc cement oT Ee 8 ADMIT PAO INOS esc ce senses sndcvsieslsichecendvenstivrcctddevesvanieesucitonaeneeeee 96 ELLIE CS ATTEOT ETRE ROE Ao: PEPEP PEPPER EEL OPTTT PPPOE AY PUREE Rete Groe te: 101 PAY RONEN A ieseercce cnc. scenceeesseeeee 8,10,12,13,16,19,21,31,33,34,36,74, 101 Artinskian/Strata .....2::<.ccrev--.0seeeensssecsrecdeos-nasess0eee tate ee 16 GSiA1iCQ, SQUAMULATIA, 5. 0...050500ae-nrenssaenencsesieosmeceone serene eeeee eer 98 Alstartellaisps) s.cscoscccseseeene- 2 ncapes tive sesso eee Pe 2 Atelestegastus Cooper and Grant ............22-:00ccneeeeeee csosasaes SOR Athyris roysii Davidson .............. . oF attenuata, Meekella ............0.2055 Alttenuatellay Stenliiyccesss2-seeseesensses==ee . attenuatus, Dyoros (DyoroS) ......-....0.0.+ . Sf AUUIOSIEZES. <2 --.4.-20ccccorpoes o ae subcostatus King ....... .. 74,76 auriculata, Paucispiniferda ........... -- 69,70 auriculatus, Dyoros)(Letragonetes)) -.c.-2<02-seaee- nen --sceeesestaeeeeeeee ee 51 Cid adee JOXFUMU reeeocneretocescas z 5§,22,27,30,42,43,44,45, 118 Australia ......... . 37,47,57,62,100, 102,104 Aviculopecten sp. repeat: 29 AWVONIG cae fc ssc occas seuseeahe ds taene secede cadences see woneee ne ee to Ro TERA ae 17 Baigendzhinian stage .. eSevossvanen oe Bairdia (sensu lato) spp. . bakeri bakeri, Neospirifer bakeri columbiarus, Neospirifer Banks, P. O. ... basiculcata (cf.), Discotomaria assis Peniculauyis: yesecnceresness eee eee . & Bathymyonia Muir-Wood and Cooper . 17,59 ?Bathymyonia cf. nevadensis (Meek) . 74 batilliformis, Collemataria ..........00.00600- . & Beattie Limestone, Florena Shale Member . 45 Belize [see British Honduras] ; Bell (1950) .... 38 bella, Echinauris ........ 25,30,62-64, 65,66,68, 121,122 Bell Canyon Formation 14,48 ,53,69,83, 104,105 Hegler Member ........ . 54,35 Lamar Member ... 54 Rader Member ............... 54 Bellerophon (?Pharkidonotus) sp. 23 ?Bellerophon sp. indet. ...... . BellizziagiAss. cic.s.: oes. sdsive des uch acs. ate. cous lessees aesseen cece eee a padcbadotoso sco 91 10,13,45,94,102 bipartita, Hustedia Bolivia .. Lake Titicaca a. «ca2iicveviisdeacousevanwsivs apleltcnksl tags fetwansese ct ene eeeee eee 6,86 Bone: Spring Pormationy cs .- Suse a eee debe heOR Co ee EEE ee Sl COMSULA SELUSLC RIO Auctiea- fants esr aeaee) teeta tee Peete shee nc aes ce eceaeanaeerite 90-93 CONVEX: RUG ALIA trevnccnesacescmsntascaens tae eoescine suche ee ve steasaenna dace ceuaieeear 78,79 ANIME TS 1 OS ETOS: (WBXYOTTOD) eenosccnonrccanc:nanooue ese ssoneacodene SacpEo-ceonbaceseaee SI Cooper iG Argy oo. cscs oncadere neces sc cee seeeies (eae sectaencs au otea Sas sa ate nies 6,37,45 Coopers (9S 6) meen ccc copper hese an ouer seats sas dee cctnaceeaeua sevaneecns 104-106 COOPEH (LOS) asec sseescine cqecis sents dete HENEDEALUILCS. 2 -ccvasccscacns=c 207+ s-nda cee eracsenccenceenvett eseatateeenees 102 ONUTI CENA AT Cenc enrens sete aencce eons esee eect aera nee meee e a ence a ceenits Soe Coee 25 GRUPIMYTESNGEOLRE © cass cceswec onc cdencecei as sos ten eco sawans ooeease aan svesektuneeees 96,97 Cryplacanihian White and ot. SOHN) 2. scsecec-sscennaenaatcos yr Soaneaseeuusecsvenss 107 Grypromellaptial lMmemtcseerctecs scores tacceet se cack othe ceene wane ietoct Sense cE eeR a 108 QUIETIMNE HELUSTC ONE = vax cece soca oon seegeus Aeee cadec dh sec Bane ue ecner ona aeee eee RE 91 CUNCALG, MAUSIERIQ cc cneteeracce seat sce sedeovse ech toasesweenaonewe aio st tea aseaaeeee Canes 91 COVICHOSCODH Uren acve sear saasc canes ea nee ooo cote eee eset tnne wate ae tee ae anes 16 Sy beoanspansct coade snide cancocanoagesapdbsasnoceunoaacncbesdancubahnccosbunteécoscognctecaunees 29 Cysrornalamia SpuOVs2)) 2ecccccses tosesadousecen-konesa carte cencsncrduevccscacsaeie lene Dasysaria Cooper, and! Grant: «.<..2s:scnscscasecveseasestcecsccaveevacconeston 75,77,80 Davidson (1860) oo ceeses jecect cee wecesesega ds consanrescncvsssnlccnsseosvsneeesvaevenuedes 93 DAVISON SG 2) notte cs rssce renee ses stuns heocae Poecnnce ostwpe eras cSueeeGne Teme eee 91 DAV IASON (LBB4) econ cee ccerecenecqcucsasersasecsave scvvorcuscesoreanevessrsnvaceuvaceaane 102 GLCONAtEnSIS; AUST ECIG) <2. .c.noccesssacecoseasst4-2otqusiscceske conesisccetasanen tenet 91 DICLONA Caron emer see creas sap ities nicene se ccucuenes eta et scat faa hene ot hia = Sane e See OTE CE RAEN SA RANKS eoec eect ndets <2. .5--< -aseaieecepacesslenserukccaue 49 Brdtmanniand| Prezbindowski ((1974))......0.5.cccn-eveccencneeccsnaeessscnnscreeenes 18 EILEEN Ror: ROMA Soden siccas od aaciraleniinaestiasbiesauizeenbes aeatasbunesecan 36 esoterica, Stauromata 2,3,4 ...... §,20,22,26,27,50,51,52,53,55,119-121 Euphemites MECMISULGATUESHEAy CHLOMIC | erckessqcssaccea= serena caves sbeeetnesaceecteossneseea 28 EEE CEOXIUISITUESMIOCHEISON sivacies vreau vdacincsestcescecastsusseessansevaunmnasne 28 ( SRCUELLE, (HELPER AES = a aconcanoncacoacoccoce-Cadncl-csea- Sea aeaeeanemasoeee 40 BRISTLE SH (Cla ME UDREIMILCSS con cseoscessenancueassoceesssecacssrenctseneeaeseese-c- 28 PERSONS CD YVOrOS DY ONOS) <> .ccncsscasniuweceséunasacenen0seseservesteesctngne+ Sl BESET SUS LDV OLOSH(D VOLS) herteceacencontoeconncsetisesns sapaaecseroaeessaaseanctesnsee 51 alafer Grant ...........-..- : ay OU fasciger, Spirifer .. 100 filosa, Derbyia . .... 45,46 filosa (cf.), Derbyia . 29,44,45,46,119 Fischer (1960)... 35 (9 Fletcherithyris Campbell . 104 BOUK (1962) .......0.50..0205 17 PROFAICErAS ....02s205-.00 20 formulosus, Neospirifer ......... elo Brakes ef al. (1969), ............... oo UO) mmanciscana (alft.); Apachella ...............00see.-ccesesvee & Biles MEPLRIILEVISIS WE ONUSIGtcctece ress coccre tierce ct necuecente ces sa SS BEAK GIES recess a ache cect serine cee cee iecuccuaen as sveeast 10 BEETS: (191 6) perce. cectessccesstocesecerctesceccnscsserseraaeraeteccosoutecsstsemsatoes 102 BARCEL IKSH (1924) pete poncenoe renee rece neceee oie an eeree ee 96,98, 100, 102 BAEK (192 6) irre ceene cosh cocwtu reese cceteeec eta ceucsseusesevcusvecectuscesdisners 100,102 RECESS (L928) cece seeeveccsecccerssvsctetettcs cases ecvensvesnsen eens ineee ones ysuns 59,70 “rail k@ (IEEE) piesa eonaadbs sa cugdackd eahoonct ten eecaade ne Rasaee SecA CAE SEE er ee eaEe enn 77 Beer anidrandlietza (Oi) icceeces cect cbesceesestcennccttee secre seeca teenth ees 8 BOTS HRV PMU [IWVOMUES | rcsccecsssseseseetiesscecesosesseseseesonenee 6,16,20,23,27,29 BRISTLE TA, ALEINOUSE #0: coseece cadets sesineseecci ons dieoeee comer creases eee 100 J CSULTGL aagSSSEISEEG RE Seo TAP BE eR EED RTS DRRUA PRE ae 10 A GHT@ SiG le seeecesotee: coc cc co pBecor PERE E RECUR EE EEE eeper PRE EEPEEReoberete rie cocareoan 107 Gaptank Formation 40 chy gce5 Pencil AL AN ROMME SANA alo noe c sce occ eon thee eee w eee neo ne TR 5 (CEI ICAT ATES ren entre ceaonen oo cCU co IDGLCOPPCCECLOOCDeBOcT DC EOOCOCE ERROR ETE DLP SER rE cre 23 Gemmellaro (1899) 98 GeolopicalliSocietyiofAmentCandccsicaccesneeeiascerssseattacoceteeesensecene smectite 5 (GOTT OTALCI Ne econ hector oo cn ITE none CORCERE EER RECACRrIe ORR RE RCE REA CECEREEEe naccnecn 96,97 GeOn ee] 93D) Aero riee cwitie cenioeie cule eetteauciclus -uvese serdel sucvamaceees cee eeeaek « 98 (CSTE TaN esc gcc bode DEO BEDOe cS COAR EE DEERE CE RERCBDE SnceHOCURE Jac aacee ScucEBHEL eA nbeCRESncad 57 GerstembonmatlOneencscacers svecastacedievssdecusiser acces ee teta eee ees 66 Gerthyandiikaausell((93\l) Weassensensmenestieseccsesncencasactec ascent 10, 13,100 Getawayuhormationy copes das cseeicatsensnescuceessesscsecssasocdesestsseweteecs torte eoeees 91 IMPOSE), tase cena temas as vecee a asian nak eane sven cae atsccrabacne a iewe=sexee eer ete seen Hueco Formation .. TAA OVO AGIO CI Os VRAIS: _ peeecoepscneacuonsacoceeserer eee: eeeene 91 narinosa: Cooperand!Grant:,......-.91,-.-5.-». eee nae 91 opsiaiGoopenand! Grant, t--s.240-ce--asansnencaniies seceeaes sie aneiecsiae eee 91 pupiiias Cooperand) Grant \-- 2. .nn-ac-noenorehesseseseesaanene eee 91 Sculptilis, Cooperiand Grant, .0...2scncansetspersver50c0ssendceest eee eases eee 91 SP eke eacane et zad et sa tea sesaene sae Nee heen vances Huxley (1869) hyporhachis, Hustedia ......... Bie. §,21,24,25,27,29,30,88—92, 93,100,125 Hystriculina Muit-Wood and Cooper .......2...0..sssecceeeeceeseoccssnecsennsens 68 TO@ZINCU9GL) coe ecw ees vate e = deseo eee sdeoes aecnces Ovect cent emacs eee ean 102 TMNDriCAlAy| COMPOSILA! |. vecpuecscsseon sececc-.0-sc- ceases encssnseatenase stants eee Stee eee 94 intrepidus!DYyOrOs) (DYOLOS)! cessccnss sec cence ener eros See seco er ese ee eee ee 51 irregularis, Gollertataria™ vai s.-c. see cesecunessteseeie side nat eect teveest sendenct coset eee eee 84 IECRINGUPIS: cdecac cause clase oeasencas de veseked cansene «seas oe oes Eee eee OR RoR 63,65,66 Itaituba Formation” 225...2.-i...0.cc- seen eecesevsceesecesscaversseecuntedeeee eee 10 IRE Tovey 2t( GIES): Casesspbectincrnnossodaacebanbadosnanonsedocosuctsnosccasaaaanacconnccnss: 72 IvieSi(18611)! wiccsacsccec-wccee cncecccessoe-cccccesndeoccsccenseceeen™ Seetn eee eee eae 78 Wvest, PEniCulauris: cc sic cseacace uses ceeescaeteen cs estoeaceeacen sete eee eee 76 PISUENSISs ECRINGUSIS ae x ctecen= save enon Secon teed apne cee n= ee nae 63 Up 301 Ss sapeacecooraadac so Eccoeuee bec uSnEReEEEOLDCOCADSnOGDODPEnGoCOaOHGanamoSoancadcoanat 6 Juresania’ Frederiks: c2.2c02s-cnecce8te soecaceessscceesse22sceeecntsee ence eee 17,59 kaibabensis (aff.), Straparollus (Euomphalus) ..........00-000cev0eeee serene 27,28 Kai babwRormation ccsrecsncccestcesssnsescaresatnesease seer asenek eReacn ethene IBIS Sco cococconcaacoe sno co sponoAsDSOoSOShAD wnocaMOAENOOaIOOAASBASHS AAs Karklins iO; Wo [OW Ritecccieccsesnccesscarcecacesnedeseaneoeneee IKeehren (1938) mecercsseccesacwes eaaveeenessoavenacesdsscacsecee 28 SeaEAIORE FSDINOSGIUNCHLOLGS ioe 5>ss<-sex co s 62 Neuman, R. B. oh sorties oie dasetiedu@enercanaeeeRetress 6 Nevada ........ Aye : Senda dutvaunc stsleifeetee ieee neeeee 66 MeVadensiss (Chay ZB ALAYINY OMI ca-n oxen deen selects ee seenaricess oe sinean teeta eee 74 Newberry (1861) ................. Newell, N. D. [NDN] ..... . 6,16,20,23-25,27-30,34 Newell Ghronicvefials (949) esecsnesescsecmeemad een asa seams 91,94 ,96,99,102 NewellhiGhronitcversal ® (1953) joc. cnet aseanetixancoacsoncnessen=enesereaneenen 10, 13,91 Newell Rigby enialy(1998)) co acn ne cnaannas ane snnesnign moh aie taee etn 47 New MEXiCO\ 20.4 /ses8e cb ielid cn ceecnesstasnssssede loobancacaszactee tana 9 ING GES ceesencccseoce soSeB ro nco ce Pano od (UO Ce ARDEA San cA cobcescoomecncnaarcaesnots oe 23,32 New Zealand .....-2c.:.c.20+<--« 37,102,104 Niviconia Cooperjand) Grant. .....<20.<<2s0c0acner stanton cites === eee 81 Nothopindax Cooperiand \Grant...<.<..:2-<.2-<<--=-s=erecer tes eee 41 notialis, Neospirifer nucella, Composita ... Nuculopsis sp. ...... nuda, Spiriferellina Nudauris Stehli ......... Oblatus\(GE:) NGL COPSISY sorcrcccner ces arate sees «eetenes niceeenss eile see eeet eee 23 oblongata, TOX MING ci sdnecscteacvereSuucenadcestaccescucsctcedtetanee sare teh ee eee eee 109 TGXQSIG) Ro aetececduccadec sx tuveesaeece sen sdaseoeteces ¢snpet i tce hee eae 108 occidentalis, IKUrorginella ccicccssvecscececssaceuceves secede oe seacesevee estan sdedeere teat eee one Meekella Productus Rugatia occidentalis parvauris, Rugatia . Odontospirifer UNDA va.cc-wererceee-ncasensi(oeeds utes eecebseee=s ee ee=- eee eens Oehlert (1888) os eee .s.beccecces-ocescsveccess cacosesqoseseaeededa aonteee eee aaa COX (1 (UE) arecononeccencanpoosenarsosace snoobscnccaoccocasnwacbScasiasccsccsnncos aed Le Oklahoma: ..2 cc. 25 acon. cosnectoes sere sedessccnseveseacnereeateseetes en eee eee Oligothyrina Cooper alleni Cooper ... Oligothyraria rier eee crane orem one: sess saececan onan eesmeneeeee SDoskeen Se (Oncosarina Cooperand)| Grants <2r.c-.c..2- one ee eoedte= sere eee sear anee ee eee Onycochilusvsp: Indets cccc.cccsckcrses ceca eset cn semaresen one ieee eee eee 28, O pik (1934 )).22.. cc. soetecdveses conven soshentece sso ee } Oppenheim (1931) es ioc. cece cn sesweccneseceqccseneemeness soreece tenant essen a eee OD SIG; FIUSLECIG) sc 2cn- cancecenc sce sececctne eres sen trieee onde e ete etn ne ee Ree opuntia, Echinauris G2Orbigny;(1842)) i. roeceenesces occ casseninetaccucttcce se eanaece en eee tence F Orthonema SP iiss cece ni hec Socgsectee nec sed rte cused do cate eees chaeee ecco encore: coat eee Gye LS (= ine aaneonsis cacnesendbk bacsconnrackcnone uiacaadbancandcstcioitacsscansrocston ?Orthonema’ Sp. indets <2 ccc. cies seceneseeceececcssstesess « ceee cote ee eee 25 new; genustatt- OrthoOnenia ..-c2e-n- coneocscne res sec es onee teense ene setae eee 24 | new genus allied to Orthonema . . 7S Orthotichia Hall and Clarke . 40,41 Otsuka Coefficient................ 13,14,16 Q@uachita’geosynclinall belt <....c22,-.c-scoscces-ceceesnccenteesentneee ee eect eee 8 Owenl(1BS7)) \.cccisercccaercedonuececuseerccdoaveecaccareanticicescher Se nieee tests tae 47 Pachy pRoiaisSp sos. ynavescctecxessnsieayacien vesntendeeae akan ghee eee ee 2B) Pajaud (1968) ... . Pakistan; s0scsv sui: scovedeeinssoneudscsetecs ssa oetuadseace aces; soothe ee 62 Paleontological Research Institution (Ithaca, NY, U.S.A.) .....cccccceeeeeeeeee 5 Palagostylus Sp > (Get. .c 0s. cnsests ans «-ne=2snuceas saecesl cas ehsae eee eee 23 Palaeozygopleuratsp. inGetin csescsvensnssewee ise te=s sees ate eee ee 23 Pal miarito Pacis cc. 22e 28s vecee eee: one nemene ents Eietner ie een eee nee 12, 13,31 Palmarito Formation ArnoldicollectionssNowArs 98l=Re yeueunausieeeres seesedseshenes st eneeeee 74,122 Field!No, .PRB-71-VE=12;...-2.02.sccsssss00suipsssoaacavsscnceaecastheee een 16 Field/No: PRH-71-VE-23. «. ..sccscrcusenecuneessessstnespasscesses doe asee eee 48,49 lOCALItV AE tree oatn ese 14-17,19,20,24,35,52,53,66,67,69,73,74,76,77, | 79,80,88,92,95,96,98,99, 101,102, 122-124 locallity,.2,22:3 .eeecsothasenesac tien ee eeeerc ee 14,15,17,20,24,35,50,51, 119 PALEONTOLOGY OF THE PALMARITO FORMATION: HOOVER 135 HO CALL 3 yaWorec.cceceostisevonessenete 14-17,21,22,31,32,35,36,46-49,82,87,88, CostatasaCoopeciandiGranteesese-eeceseccencemeece nse senstemccNesttd recent esee won e) 90,92—96, 103,104, 106,119, 124-126 BVE STINE W DEITY) Mies axe nsessesnanw enue cnervesunesensrewernbevouwesceunmeceetieencettee 76 NOCANIDY TAY cen vecee«ccceeens =x 14-17,22,32,35,36,43,44,46—49,52-55,65,66,70, mekeei: Muir-Wood and) Coopen ...-c..sc1sscicsccreeestivdectsseresecaserneae 74-76 71,73,74,78,82,95,96, 101,102, 118,119,121-125 DENiculiyeratGOope wand Gran tumencncae eset acceceeseseerserssvencecesessise seme 76 HOGA typ Ssccpecvcs sant ance secsciesacsscvescusssecesece 14,15,17,23,31,32,35,76,77,123 SUDCOSL ALA (UKING) Nenececcnercnciceneeete «pick sane ssecacecsrecesyaavecceeecdesstereees 76 locality 6... 14-17,24,25,30,31,35—37,60,61,88,90,121,124—127 subcostata latinamericana Nn. ssp....... Cixi 5,20,23,75-77,78,79,81,123 block A .. 24,25,31,32,40,56—58,60,83 ,84,90,92,97,98, 105,108,118 subcostata subcostata) (KING) oe ccn neces -eoae-cececs sre nsenes duceeweesesceteee eee 76 BIOCKIB ty acschacsteesvedeececece es 24,25,56-58,83,84,87,88,92,97,98, 105,108 transversauCoope sande Granbrsesencre-sensxsachadcuecermeceteeebaar eeeuecterstire 76 DIOCKS Gato ert ccesesiscvareasssctcss 17,24,25,32,40,46,47,56—58,60,61,63,64, IDENICUII fer, TPEMiGULAUNIS) jescuvcccsuenecesciosenescesesecess cee teeeastaracenaeteet ers 76 83,84,87,88,90,92,97,98, 105,108,118 PENANNUlALA WANISOPN Ql tec scant exccurc esd sueestec sere tee cnancant retaceatcenee ates 28 I@YeETISY 7/ Se -soncmancosceocooRBes:oscu0aD 14-17,24,26,35,40,41,48,49,52,53,65,66, PermiansRatiomeeeerennscsecsecsecsrciescsesscowatdescadetscvaceste recs 5,6, 16,19,33-35 73,74,80,95 ,96,98-102,118-120,125,126 Permophricod Othyrismb.aNlOValecsn-scoet veer saeesseaes eeeee sees seecsesceseaneesesacias 98 NaGality: S/o... .ccesecees 14-18, 26,32,35—37,43,44,48 ,49,52-55,66,69-74,78, Perrinilesnhillinw. sac, coc the seer twe on cee Meee eee see ee nen Se ees tla ae Sen 16,23 81,85,86,88,92 ,95,96,98—-102, 118,119, 121-126 PON reac se seca s wavni vies seapiecsesascn tas enesseeeme esse ccuranct'eutocwedcanedetraas 10,13,91 BOCUIRU BLOM icoc nceaee:canestscewevewes veots 14-17,27,28,31,32,35,45,67,68,72,78, Wak ev TiticaGarss sain eiss dae Ae eo 105 BRESUBNECISC Ceca ceas act tc wate ae tice soc ee ccteneocganeeailneeteau cess snore diese 76 IPS CUAOMONOLISISD a een teette ha ee ae ca tscn cannlonainen se stneeseetiesecaeea estates 28-30 136 BULLETIN 313 Pseudopermophorus sp. TRU TEES RTT “seca Resee eee 80 S20 SOUR ECO REDE DOICOLO COO O-C OAc OOK I aIIS 91 Pugnoides LER LAT SE GLY tee nana acos Scare enn ssate ae nee cane cee tas eaaksien sense sie sc asieletenfeteaar AIBPAOS USIITS Seca ss8 specs se5e 02ELC CHOROID ROS DU CREDE RESoe cOmenpaceRCocoD DESC REXANUS RIN Dees mene nes se races ccscthasacs~ acceeecare-sunudersaddduessucenancenracnare= REZ VBS SIN UIENRG Soansnsbessoes scape sane ee anos subchesancencanosoneceaoonesos PPUMCLOSDIFIEYRIN OL Nocera acane- ere sex on sae stene contre te ee nem e se ase pyriformis, Composita quadrangulatus, Dyoros (TetragOnetes) ......--+.-00cceee reese eet eecn een eeen ees 51 IQUOAI ALA LAUCISDINISENG seccwe-mejetanassavnder jeer Secresiiensen= ems eseethrmr doa 70 quadratus, SVR LRETRS sche sees HE scace cee eceet oosencbonncconderconnoneneene a aoe seeeee ase ese 80,81 ZOTOSIBEOS 225500 PASCAL O CRO RET DOOLDIEDEOD UII ODEO MELNOT TEAS MONOCSBODO SII SAIOSIES 56 (GIG FTIE NE TTIES SiG 7 Nes gp seearacecn ster rico coeocSncc ase auiaaec So one oasee CCDS IES 17,49 (QUESEE sesecetesecneodecdocc conc O-conoo SneRgoe aS acoSSACEnceCoHecoNSEMneDOgoTeoHOSUE ELC 23,32 RORIAQVECIUSE SOD litesteereae-eaceanacecacastscuncsceseeteserenereatercedanncces 14,17,59 IROIMAVE CLUS 2 wa csveqscakenscecccssucavcesdessscucdsaceencscecses chescedesseceessrsceeste 33,35 Ramsbattorn (L952) bac cpnccnanect etre o-cest mands fee eoe hs vankak vetiex cs One Peeceemates 52553 rara, Gleiothyridimaveercncss tec oce cosce 7. sedeps ose tecececnnarssnetounewencteeesreseoncts eclece 94 Paucispinifera pone: fA) Raymond (1911)..............--. ~sw 89 rectangulata, Paucispinifera .. 70 Rectintarcinata Gl eClornyridinGy orcs. secercecssenese cree seen sececter ete seae seco 94 ANS! TEOTMTELEOS!? — ecobeoses soeccascoobocecosctesocesnoconocoaaeococaoccbbecosooorenubos 11 Red (944) corer oi: vv om ssincacsctinsscisnes cian cules cutemeeanaee ess toeaceamees eeeendey 62,102 TPP UNATIS NET DVE hie cen cece rac css nna oats eeenieeeae sence ss aerneea ee eee nen oee rae east 41 Retaria umbonata Muir-Wood and Cooper 72 Reticulariina Frederiks. ............- 102 Reticulatia Muir-Wood and Cooper . 77,80 RELISHIF AGS Pale Cammntiees ce nnc vaenck ween s on chueoancasemennoneoenes reese eokecmeenes 28 RREEZUUSH (L781) Sow -ceeenan soneceniccee=- sous ocoslon corer mee tetas encanta emcce reece tees 39 PEVESSUS EC HONEIUICLES ae ee cninseaencnee sean stec se <5 dencces scacecuseeetee stereos 77-719 convexa' Cooper and) Grant 2cie.cs0se cco iecsseecsccatect Tete eee eee 78,79 incurvata (King) ....... intermedia Nn. Sp. .........-. MmakeenCooperand Grant: ..ccs.s-.s2-ndevecerccnsvncceasarteer ce eee 78,79 occidentalis (Newberry) .............00.0+ 6 ...... 20,26,76,77, 78-80, 81,123 parvauns Gooperand Grant) 2... ccresccucse-cacvesnere a tecteeer tea eee 79 DOraticas (MCKGE)\..2.5-svscsccvansencscnceacuxs Ceesee tne Ta RR Rugosochonetes Sokolskaya .. rupinata, Hustedia 12,31 Sabaneta facies .... Per 12,19,23,27,31 Sabaneta Formation . Sabanetal Groups: 22 ceseze ae oe cw dele none dene eae aren acuie eee ae ee 1 Sabaneta\Seiies ead tet A nal d eS. 1 Salt Range 2c x2s 2550. Bie dite asc ctce cadens nccenccdeavcveceovyeshpesehesteass eee 1 SaMiataNTUst edi dizew-2) crsevede os v0de oxo dort ods Sev Sedov vdevs eee Code aenE 91 1 Sampling Efficiency Index ................0++e00+» 5,8,19,35-37 Sa MELE Be ral (970) woe mine nee testes tees ase aoe loa e eee 13,34, 72 Sanguinolites sp. .... 28-30 SantavRosalGrovprrestscsasssicedesatenanescearsneencss ewan \ Macal Series ¥i20. 02: e2-c0s set ecse sahee eens deeveccus Sapper (1937) sod ceewsshs eee oi eae etean saves evce snc ee evade vee teeee es eee pe eee Sarganostega Cooper and! Grant 22..020.00..cs.venesesseeeeeueernere an ceeeeeeeee Sarytchevaii(197/1)) cs hese eee Ra cawesscccecnepeeh dost ce eee eee ene 7 Scenesia Cooper and Grant) [Pees cao. seeeeree een eee nese nessa 102, ‘Schaub (1944) iss 2 cde. Sse dvSod sevess coozeescctbes.asccee teehee ee 1g Schizodus canalis Branson sf 6,20,27 ‘Schizophoria*Kinig. .co.se2..eh-doth arse dt eeeh «coe v0 sa vena aoceeae Coe eee 40 Schlotheimi(1816)-%..22. Asie. icdi ater vs ceac see Oe ee 102,104 Schucherti (1913)! sss. REE ek Ricerca en 104 Schuchert (1935) 2.2202. p..220cccestzscdctseasseoseaautevee--2 pate ee 10 Schuchert:and Cooper (1932)... .<.-s:s<0<00----sveanxendav=<20es ses 40° Schuchert and LeVene (1929).. 40. Schiimann (1969) .... 22,30 Schwagerina setum . P| Scotese: ef al. (1979). <..<2-c2s2 cen: cadvecsaneoesnanesnsanvseecqse see eee eae ee eee 33 Seruttons (G21: (GMS) eeec.s 22: sescssassacceeceotsostsescee eee 6,20,21,25: 29 SCUIPHILIS, JAUSCEAIA: (coscn--+snenconensavusanansosesna ens n 29,108,109, 127 Texasia oblongata Cooper and Grant 222.22 scccevecencs- soe ccssaeeneeoonee eae 108 texta; "Der byia: osisccciecsenedaaddoccvotseucsstsdooes tee ro eeen tone stent ene eee 44 JRE AT oe mosonemenepaaonr somone moa’ nncboscbonpencr nour pocopanoccnAce 25,55—57,62,84,97 KeOIMUG ssi geitewartinss