Pelecypoda and Rostroconchia of the Anisden Formation (Mississippian and Pennsylvanian) of Wyoming

Pelecypoda and Rostroconchia of the Anisden Formation (Mississippian and Pennsylvanian) of Wyoming

GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-E Pelecypoda and Rostroconchia of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming

By MACKENZIE GORDON, JR., and JOHN POJETA, JR. THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-E

Descriptions and illustrations of 41 taxa of pelecypods and 1 rostroconchian, with comments on their distribution

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1975 UNITED STATES DEPARTMENT OF THE INTERIOR

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data Gordon, Mackenzie, 1913- Pelecypoda and Rostroconchia of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming. (The Amsden Formation (Mississippian and Pennsylvanian) of Wyoming) (Professional paper Geological Sur­ vey ; 848-E) Bibliography: p. Includes index. Supt. of Docs, no.: I 19.16:848-E. 1. Lamellibranchiata, Fossil. 2. Rostroconchia. 3. Paleontology Carboniferous. 4. Paleontology Wyoming. I. Po- jeta, John, joint author. II. Title. III. Series. IV. Series: United States. Geological Survey. Professional paper ; 848-E. QE811.G67 564'11'09787 74-32078

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 024-001-02638-4 CONTENTS

Page Page Abstract _ . El Composition of the fauna Continued Introduction. ______. 1 Stratigraphic considerations _,______E4 Previous work ______. 1 Geographic and stratigraphic occurrence of the Present investigation ______2 pelecypods ______4 Acknowledgments ______. 2 Mississippian fauna ______5 Pennsylvanian fauna ______7 Composition of the fauna ______. 2 Rostroconchians ______Faunal diversity ______. 3 Systematic paleontology ______Relation to the Mississippian-Pennsylvanian References cited ______20 boundary ______Index ______23

ILLUSTRATIONS

[Plates follow index] PLATE 1. Palaeotaxodonta. 2. Isofilibranchia? and Pteriomorpha. 3. Pteriomorpha and Heteroconchia. 4. Heteroconchia, Anomalodesmata, and Rostroconchia.

Page FIGURE 1. Diagrammatic sketch of muscle scar pattern of Paleyoldia ams- denensis (Branson and Greger) ______ElO

TABLES

Page TABLE 1. Taxonomic relationships and relative abundance of pelecypods in the Amsden Formation ______E3 2. Major life-habit groups of Amsden pelecypods ____ 3 3. Pelecypod and rostroconchian fauna of the Amsden Formation of Wyoming ______5 4. Checklist of pelecypod and rostroconchian collections ______6

in

THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

By MACKENZIE GORDON, JR., and JOHN POJETA, JR.

ABSTRACT lies. Our study of this fauna has provided informa­ The study of the pelecypods of the Amsden Formation tion as to what happened to this important mollus- of Wyoming is based on 285 specimens from the collections can class as it crossed the Mississippian-Pennsyl­ of the U.S. Geological Survey, the U.S. National Museum, vanian boundary and has added to our knowledge of the University of Missouri, and the University of Wyoming. the mode of life and diversification of pelecypods in Of these, 275 are recognizable at least to genus and are as­ signed to 16 families, 22 genera, and 41 species. Although the late Paleozoic. this material is not particularly well preserved, it is suffi­ The pelecypod fauna of the Amsden Formation is cient to show pelecypod diversity at the species level on highly varied. Compared to the brachiopods, the both sides of the Mississippian-Pennsylvanian boundary. Thus pelscypods are much fewer in number, but there is it helps to fill a gap in existing knowledge. In the late greater diversity in proportion to their number. Our Paleozoic, most pelecypod genera are long ranging and are of little use as biostratigraphic tools; at the species level study of these pelecypods was based upon 285 speci­ the pelecypods can be useful in this respect. Although all mens from the collections of several institutions. Of of the Amsden specimens are assigned to Mississippian or these specimens, 8 are unidentifiable below clr.ss Pennsylvanian parts of the formation, this has been ac­ level, 2 are identifiable only to subclass, and the re­ complished almost solely by reliance on the foraminifers maining 275 are considered to belong in 41 species, and brachiopods. All the principal subclasses of late Paleozoic pelecypods 22 genera, and 16 families. are present in the Amsden, as are a quarter of all Paleo­ zoic families; the latter include all the common marine PREVIOUS WORK late Paleozoic families with the exception of the Parallel- odoritidae. Relatively little work has been done previously on Because of the poor preservation of the material, the the Amsden pelecypods. They have figured only in­ nomenclature is of necessity limited. Only five taxa have cidentally in three brief descriptive papers. Branson been identified to species; one of these, Aviculopecten gravidus, is new. A lectotype is designated for Paleyoldia and Greger (1918, p. 321-323, pi. 19, figs. 11, 23-26; amsdenensis (Branson and Greger). The rostroconchians are text fig. 1) described and figured three species of limited to a single fragmentary specimen. pelecypods in their paper on the Amsden fauna. These are listed below, together with our present INTRODUCTION assignments.

All too often the less well preserved elements of a Branson and Greger (1918) This paper fossil biota are omitted in otherwise comprehensive Microdon cf. M. oblongus (Hall) ..Nuculo>psis*sp. A systematic studies, yet these organisms may have Cypricardella sp. formed an important part of the biota. Even though Myalina sancti-ludovici such fossils do not lend themselves to formal de­ (Worthen) ______Septimyalina sp. Paleoneilo amsdenensis n. sp __ -Paleyoldia amsdenensis scriptive paleontology, they may fill important gaps (Branson and Greger') in paleontologic knowledge. We include, therefore, a special chapter on the Amsden pelecypod fauna C. C. Branson (1937, p. 657, 658, pi. 89, fig. which, although restricted in its distribution and added three more species to the list, one a rostro- generally not well preserved, contains representa­ conchian; these are cited below in the same manner tives of 25 percent of all Paleozoic pelecypod fami­ as above. El E2 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

C. C. Branson (1937) This paper material belongs to the U.S. National Museum Nucula sp ______Nuculopsis sp. A. (USNM), the University of Missouri (UM), and Schizodus sp ______Schizodus cf. S. depressus (Worthen). the University of Wyoming (UW). Conocardium orientale n. sp _ Conocardium orientale C. C. Branson. ACKNOWLEDGMENTS Burk (1954, p. 14, 15, pi. 1, figs. 38-40) added We are grateful to our colleagues from other in­ Allorisma terminate (Hall) to the list. His material stitutions who have loaned us Amsden pelecypods is included in the present paper as Sanguinolites sp., for this study. We thank G. A. Cooper and E. G. Wilkingia terminalis (Hall), and W. sp. Kauffman of the U.S. National Museum, A. G. All previously described material has come from Unklesbay, J. A. Wolleben, R. L. Ethington, R. E. the Mississippian part of the Amsden in the Wind Peck, and J. H. Witt of the University of Missouri, River Range. The fauna from the Pennsylvanian and D. W. Boyd of the University of Wyoming for part of the formation has been cited only in faunal this kindness. Photographs were prepared by Robert lists. The original description of the Amsden Forma­ McKinney and Haruo Mochizuki, U.S. Geological tion (Barton, 1906, p. 34) listed one collection of survey. The manuscript was reviewed by E. G. Pennsylvanian age among which several species of Kauffman and E. L. Yochelson. pelecypods had been identified by Girty and assigned to Edmondia, Pleurophorus [ = Permophorus~], and COMPOSITION OF THE FAUFA Entolium [=Pernopecten~\. These are included in All of the major subclasses recognized by Pojeta the present study (colln. 52). (1971) are present in the Amsden, although the Blackwelder (1913, p. 176) also published Girty's occurrence of the Isofilibranchia is based on ques­ identifications of several pelecypods from the Missis­ tionable material. Considering the number of speci­ sippian part of the Amsden and a rostroconchian mens at the subclass level one finds the following from the Pennsylvanian part, both in the section at representation: Palaeotaxodonta (30.? percent), Darwin Peak. We have also restudied and briefly de­ Isofilibranchia (0.7 percent), Pteriomorpha (32.9 scribed this material (collns. 137, 139). percent), Heteroconchia (20.9 percent), and Ano- Shaw (1955, p. 63) listed some pelecypods from malodesmata (15.2 percent). The class Rostrocon- the vicinity of Rawlins, Wyo., and mentioned a pele- chia is represented by a single fragmentary speci­ cypod fauna not yet studied. We have not seen men. Shaw's Rawlins material but some of the species are In table 1 the families and genera of pelecypods probably the same as those in our collections from recorded in the Amsden Formation are listed, the the Rawlins hills (collns. 1, 2, 3, 5). number of specimens of Mississippian age and of Pennsylvanian age and the total for each genus are PRESENT INVESTIGATION given, as are the percentages of the total number of Our study of the Amsden pelecypods includes a pelecypods that these figures represent. The isofili- restudy of material in the collections of the Uni­ branchians (two specimens) have been omitted versity of Missouri and the University of Wyoming from this table because they are not identifiable as that has been described and figured or mentioned by to family and genus. previous authors and also includes description of Amsden pelecypods can be divided into three ma­ new material from the collections of the U.S. Na­ jor life-habit groups: infaunal labial palp deposit tional Museum and the U.S. Geological Survey. feeders, burrowing infaunal suspension feeders, and Because of the generally poor preservation of the attached suspension feeders. The distribution of the Amsden pelecypods, only five species, one of them Amsden genera in these groups is shown in table 2. new, are cited by name in this report. Formal de­ In our selection of these groups no attempt has been scriptions are given only for the better preserved made to separate attached epifaunal suspension material. Nearly all of the specimens are identified feeders (epibyssate and cemented species) from as to genus, some in terms of a closely allied or attached semi-infaunal suspension feeders (endo- possibly identical species. Lectotypes have been byssate species). Stanley (1972) proposed that the chosen where necessary and synonymies are given great bulk of equivalved byssate pelecypods with where appropriate. The synonymies have been com­ anterior lobes were semi-infaunal (endobyssate). piled from the literature and, for the most part, do Kauffman (1969) felt that many mytilids with an not imply actual examination of the specimens. Type anterior lobe were epifaunal and related current PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION OF WYOMING E3

TABLE 1. Taxonomic relationships and relative abundance of pelecypods in the Amsden Formation

Mississippian Pennsylyanian specimens specimens Totals Family Genus Number Percent Number Percent Number Percent 4 1.46 7 2.54 11 4.00 _ __ 2 .73 2 .73 Paleyoldia ______69 25.09 2 .73 71 25.82 _ _ 13 4.73 13 4.73 9 3.27 2 .73 11 4.00 1 .36 _ _ __ 1 .36 1 .36 15 5.45 16 5.81 Posidoniidae Posidonici 4 1.46 4 1.46 Entoliidae ______- Pernopecten ______3 1.09 3 1.09 Aviculopectinidae _ _ Streblopteria _ ____ 1 -36 1 .36 Aviculopecten ______14 5.09 26 9.45 40 14.54 8 2.91 10 3.64 18 6.55 4 1.46 23 8.36 27 9.82 2 .73 ______2 .73 1 .36 10 3.64 11 4.00 Edmondiidae ______Edmondia ______9 3.27 9 3.27 Grammysiidae ______Sphenotus ______2 .73 _ .. 2 .73 Sanguinolites ______1 .36 _ ____ 1 .36 Sedgwickia _____ - 1 .36 1 .36 Pholadomyidae _ __ _ Wilkingia ______8 2.91 21 7.64 29 10.55 Total ______]L29 46.91 146 53.08 275 99.99

flow patterns to the shell morphology of such ex­ 1968). Although some of the genera found in the posed forms. The empirical base from which Stanley Amsden are limited to either its Mississippian or drew his conclusions is rather small; most of his Pennsylvanian parts, elsewhere all of them except hypothesis is based upon the study of eight species Paleyoldia and Caneyella range from Mississippian of mytilids from the North Atlantic. Stanley's hy­ into Permian rocks. Some of the genera range down­ pothesis nevertheless has great potential as a unify­ ward into the middle Paleozoic and some upwrrd ing concept in the study of attached pelecypods. It into the Mesozoic. In contrast to generic stability, needs a broader data base, however, particularly however, numerous demonstrable differences exist one derived from the study of fossil forms that have between Mississippian and Pennsylvanian specimens been preserved in place. of these genera that occur in both parts of the for­ mation. For the most part, we have treated these TABLE 2. Major life-habit groups of Amsden pelecypods morphological differences as indicating different

Infaunal labial palp Infaunal burrowing Attached suspension species. Thus we see no period of late Paleozoic sta­ deposit feeders suspension feeders feeders bility at the species level. Nuculopsis Schizodus Myalina In North America, except for a relatively few Phestia Permophorus Septimyalina taxa, it is difficult to recognize the upper Paleozoic Paleyoldia Astartella Pseudomon&tis Cypricardella Posidonia systems and series on the basis of pelecypod genera Edmondia Pernopecten alone. One must turn instead to pelecypod species. Sphenotus Streblopteria Sanguinolites Aviculopecten Unfortunately, except for the aviculopectinids and Sedgtvickia Aviculopinna myalinids (Newell 1937, 1942), the species-level Wilkingia Leptodesma Caneyella taxonomy of North American late Paleozoic pele­ Isofilibranchian? cypods is poorly understood and badly in need of monographic systematic treatment. FAUNAL DIVERSITY RELATION TO THE The diversity of the Amsden pelecypod fauna is MISSISSIPPIAN-PENNSYLVANIAN BOUNDARY noteworthy. Representatives of all the common ma­ rine late Paleozoic families, except the Parallelo- Our study of 41 species shows that 21 are preso.nt dontidae, have been found in the formation. At the in the Mississippian part of the formation and 22 generic level the Amsden fauna supports the con­ occur in the Pennsylvanian part; 2 species, Per­ cept of a period of late Paleozoic stability in the mophorus sp. A and Wilkingia terminalis (Hall), increase in diversity of the Pelecypoda (Stanley, occur in both parts. Although some Amsden genera E4 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING seem to be restricted to either the Miasissippian or The pelecypod distribution is, for the most part, the Pennsylvanian, all of the genera present in the the same as the coral and brachiopo

In table 3 the distribution of the pelecypods and 20 to 25 miles south of Lander; this area has also rostroconchians by collection and by stratigraphic been the most thoroughly collected. member is shown. The Amsden collections have been Lincoln County. The earliest pelecypods in the given numbers from 1 to 160 for the purpose of Amsden are two incomplete valves referred to Avi- simplification; full descriptions are given in Sando, culopecten sp., which were collected in the Moffat Gordon, and Dutro (1974). A checklist of the pele- Trail and Covey Cutoff sections (collns. 79, 92), cypod and rostroconchian collections is given in associated with corals of the Caninia Zone and table 4. foraminifers of Mamet's Zone 17 of middle Chest er- ian age (see Mamet, 1974). These were the only MISSISSIPPIAN FAUNA pelecypods found in the Moffat Trail Limestone Pelecypods are sporadically distributed in the Member. Mississippian part of the Amsden in the western Teton County. At Hoback Canyon, in the moun­ and central regions of its outcrop. Most of our speci­ tain range of the same name, Aviculopecten sp. A. is mens have come from the drainage basin of the present in the Horseshoe Shale Member (colln. 118) Little Popo Agie River in the Wind River Range, a few feet below the base of the Moffat Trail Lime-

TABLE 3. Pelecypod and rostroconchian fauna of the Amsden Formation of Wyoming

Mof­ fat Trail Ranches ter Horseshoe Shale Member Lime­ Limestone stone Member Mem­ ber 1 2 3 5 20 22 27 28 29 30 31 36a 36b 36c 36d 36e 41 43 46 53 118 137 159 79 92 40 50 52 67 130 131 139 Pelecypoda: Nuculopsis sp. A . ______X X ______sp. B __ -_ __ _- __ _- ______-______X ______X ______Phestia sp ______-- ______X ______PaleyoLdia amsdenensis (Branson and Greger) ______X __ X ______X __ X ______sp ______... ______X ______X ______Isofilibranchian? gen. and sp. indet _ _ - -- ______X X ______Myalina (Myalina) sp X ______. __ Septimyalina sp. A ______X X _ _ _ __ ? ______Septimyalinal sp. indet . ______X X Caneyella sp _ . ______-_ -______X ______Leptodesma spp _ _ . -- -- X ______X __ __ Posidonia sp. indet . -- _ __ X ______Aviculopinna sp _ _ .-- _- -- ______- ______X ______Pernopecten sp. indet .-- ______X ______Pseudomonotis sp _ .------_- ______- ______X ______Streblopteria sp. indet ____ -- _- ______X ______Aviculopecten gravidus n. sp __-___-_ . - - X ______sp. A ______. ______.______X ______sp. B ______. __ X ______X ______spp. indet ______. X ______X X ______X ______X X ______Schizodus cf. S. depressus Worthen ______X __ __ X ? ______X ______aff. S. affinis Herrick . _ __ -______- -______X X ______alpinns (Hall)? ___. ______X ______sp. A _ . -- -______X _ _ __ _ ------_- __ sp. B ______. -- -_ X ______-______Permophorus sp. A ____. __ ? ______X __ __ X ______X X ______Cypricardella sp ______. -- ______X __ _ ------______Cypricardellal sp. indet __.-______X ______Astartella concentrica (Conrad) ______- __ ? __ .______-_ X ______XXX ______sp ______.-- ______X ______Edmondia spp ______.-______X XX ______Spfienotus sp ______. -- ______? ______X ______Sangninolites sp ______. ______X ______Sedgwickial sp. indet ___. -- __ __ X ______Wilkingia terminate (Hall) X X X X ______X X ______X ______sp ______. _- __ X ______.______Rostroconchia: "Conocardium" sp. indet __. -- -- ______X EG THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

TABLE 4. Checklist of pelecypod and rostroconchian collections from the Amsden Formation

Collec­ tion Permanent No. institutional Name of locality Mountain range County Location Member in locality No. report

1 . USGS 5441-PC __ Cherokee Spring _ Rawlins hills __ Carbon ___ Probably in SW% sec. 11, Horseshoe T. 21 N., R. 88 W. Shale. 2 . USGS 8071-PC __ ___do ______do ______do __ Probably in SW 1^ sec. 11, Do. T. 21 N., R. 88 W. 3 . USGS 3139-PC __ ___do ______do ______do __ NW%SW% sec. 11, T. 21 Do. N., R. 88 W. 5 . USGS 3085-PC __ Cherokee Peak __ ___do ______do __ SE%NE% sec. 10, T. 21 Do. N., R. 88 W. 20 . USGS 19285-PC _ Tweed Creek ___ Wind River Fremont ___ Probably in SE^ sec. 22, Do. Range. T. 30 N., R. 99 W. 22 . UW 3099/9A __ South Pass ______do ______do __ Center sec. 9, T. 30 N., Do. R. 99 W. 27 . USGS 19283-PC _ Cherry Creek __ ___dx> ______do __ Probably in sec. 30. T. 31 Do. N., R. 99 W. 28 . UW 3199/19B2 __ ___do ______do ______do _.__ SE^NW^ sec. 19, T. 31 Do. N., R. 99 W. 29 . UW 3199/19B3 __ ___do ______do ______do __ ___do ______- Do. 30 . UW 3199/19B4 __ __.do ______do ______do __ ___do ______. Do. 31 . UW 3199/19B5 __ ___do ______do ______do ______do ______. Do. 36a UM specimens _ ___do ______do ______do __ Sec. 19, T. 31 N., R. 99 W. Do. 36b ___do ______Cherry Creek(?) _ ____do ______do ____ Same, but labeled "sec. 31, Do. T. 19 N., R. 99 W." 36c ___do ______Near Lander ______do ______do ____ Exactly locality not known. Do. 36d ____do ______Little Popo Agie ___do ______do ______do ______. Do. River. 36e USNM 487A __ Cherry Creek __ ___do ______do __ Sec. 19, T. 31 N., R. 99 W. Do. 40 . USGS 21676-PC _ Bull Lake Creek _ ___do ______do __ SW% sec. 2, T. 2 N., Ranchester R. 4 W. Limestone. 41 . USGS 19156-PC _ Soda Creek ____ Washakie Teton ____ Trail in sec. 5, T. 45 N.. Horseshoe Range. R. 110 W. Shale. 43 . UW 43106/19B _ Horse Creek ______do ______Fremont __ SW 1^ sec. 19, T. 43 N., Do. R. 106 W. 46 . USGS 16197-PC _ Wiggins Fork __ ___do ______do __ SW% sec. 7, T. 42 N., Do. R. 105 W. 50 . USGS 19187-PC _ Trout Creek ___ Big-horn Washakie __ Sec. 19, T. 41 N., R. 88 W. Ranchester Mountains. Limestone. 52 . USGS 2461-PC, North Fork, Crazy ___do ____ Johnson __ SE% sec. 28 or NE 1^ sei. Do. 2461A-PC. Woman Creek. 33, T. 49 N., R. 83 W. 53 . USGS 19241-PC _ South Fork, Rock ___do ______do __ SW% sec. 25, T. 52 N., Horseshoe Creek. R. 84 W. Shale. 67 . USGS 16215-PC _ Amsden Creek __ ___do ____ Sheridan __ SW 1^ sec. 34, T. 57 N., Ranchester R. 87 W. Limestone. 79 . USGS 22981-PC _ Moffat Trail ___ Salt River Lincoln __ NW%NE% sec. 3, T. 3f Moffat Range. N., R. 117 W. Trail Limestone. 92 . USGS 6965-PC __ Covey Cutoff ______do ______do __ NWHNE^, sec. 27, T. 34 Do. N., R. 117 W. 118 . USGS 16207-PC _ Hoback Canyon __ Hoback range _ Teton ____ Sec. 2, T. 38 N., R. 115 W. Horseshoe Shale. 130 . USGS 18786-PC _ ___do ______do ______do __ Sec. 2, T. 38 N., R. 115 Vr. Ranchester Limestone. 131 . USGS 16210-PC _ ___do ______do ______do __ ___do ______- Do. 137 . USGS 6191-PC __ Darwin Peak ___ Gros Ventre ___do __ S% sec. 28, T. 40 N., Horseshoe Range. R. 112 W. Shale. 139 . USGS 6191A-PC _ ___do ______do ______do __ S% sec. 28, T. 40 N., Ranchester R. 112 W. Limestone. 159 . USGS 24050-PC _ Elk Ridge ____ Teton Range __ ___do __ SW^ sec. 26, T. 47 N., Horseshoe R. 116 W. Shale. stone Member. The base of the Moffat Trail Lime­ conch pelecypod identified as Astartella sp. was stone Member is shown by Mamet's foraminiferal found in the basal 10 feet of the Horseshoe Shale studies to be somewhat younger here than in Lin­ Member (colln. 41). It was associated with a brac- coln County due to transgressive stratigraphic rela­ iopod fauna that includes Diaphragmvs nivosus n. tionships, so this Aviculopecten may not be quite as sp., a productoid characteristic of the Heath Shale early as the previously cited species. of Montana of Late Mississippian (Che^terian) age. At Soda Creek in the Washakie Range, a hetero- The Darwin Peak section in the Gros Ventre PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION OF WYOMING E7

Range includes a limestone bed near the middle of Teton County. In the section at Hoback Canyon, the Horseshoe Shale Member (colln. 137), in which a myalinid species identified as Septwiyalinat sp. is the pelecypods Septimyalina sp. A? and Sphenotus present in the Antiquatonia blaekwelderi Zone in sp. were found associated with brachiopods char­ the Ranchester Limestone Member (collns. 130, acteristic of the Carlinia amsdenia-na Subzone. 131). This is the only pelecypod species found in the At Berry Creek in the Teton Range, the highest Pennsylvanian part of the Amsden in its western Mississippian beds in the upper part of the Horse­ region. shoe Shale Member (colln. 159) contained Per- Fremont County. At Bull Lake Creek in the mophorus sp. A and some pelecypods that are un­ Wind River Range a bed of fine-grained, very light identifiable because they are poorly preserved. The gray dolomite at the base of the Ranchester Lime­ Berry Creek beds are in B. L. Mamet's foraminif- stone Member (colln. 40) contains a molluscan mold eral Zone 19. (See Mamet, 1974.) fauna which includes the following pelecypods: Fremont County. In the drainage basin of the Schizodus aff. S. affinis Herrick, Astartella concen- Little Popo Agie River, which includes Cherry trica (Conrad), Edmondia sp., and some indeter­ Creek, considerable collecting over a period of years minate pelecypods. This mold assemblage is the only has turned up the following pelecypods, most, if not one of Pennsylvanian age found in the central re­ all of which are probably from the Carlinia amsden- gion, and here the mollusks served to date the rocks. iana Subzone (collns. 20, 27-31, 36a-e) : Washakie County. At Trout Creek, on the west­ Nuculopsis sp. A ern slope of the Bighorn Mountains (colln. 50), a Paleyoldia amsdenensis (Branson and Greger) Isofilibranchian?, gen. and sp. indet. tan marlstone has provided a fairly large molluscan Septimyalina sp. A fauna, among which are the following pelecypods: Leptodesma sp. Nticulopsis sp. B. Aviculopecten sp. indet. Phestia sp. Schizodus cf. S. depressus Worthen Paleyoldia sp. sp. A Leptodesma sp. Cypricardella sp. Amculopecten sp. B Cypricardellal sp. indet. Schizodus aff. MOLLUSCA stone Member (colln. 52) has also yielded a pre­ Class PELECYPODA Subclass PALAEOTAXODONTA dominantly molluscan fauna among which are the Order NUCULOIDA following pelecypods: Superfamily NUCULACEA Gray Family NUCULIDAE Gray Pernopecten sp. indet. Genus NUCULOPSIS Girty, 1911 Pseudomotiotis sp. Nuculopsis sp. A Permophorus sp. A Plate 1, figures 1-5 Astartella concentrica (Conrad) Edmondia 3 spp. Microdon cf. M. oblongus (Hall). Branson and Greger, 1918 [part], p. 321, 322, pi. 19, fig. 11 [not fig. 25]. The stratigraphic position of this collection suggests Nucula sp. C. Branson, 1937, p. 658. that it is post-early Morrowan, but whether it is Four limonitic internal molds of Niiculopsis, from late Morrowan or early Atokan in age is not yet the Mississippian part of the formation in the Wind known. River Range, are present in the University of Mis­ Carbon County. In the region of the Rawlins souri collections (UM 2657, 6630, 12791). The molds hills, collections made in the vicinity of Cherokee are elongate, suboval to subtriangular in outline, Spring and at Cherokee Peak (collns. 1, 2, 3, 5) have prominent umbos, and are boat-shaped in dor­ from the Neokoninckophyllum hamatilis Zone in the sal view, being narrow posteriorly, truncated and Horseshoe Shale Member contain the following pele­ beveled anteriorly. They range from about 8 to 16 cypods : mm in length, 6 to 11 mm in height, and 4.5 to 8.5 Myalina (Myalina) sp. mm in width. The umbos are opisthogyral and lo­ Aviwilopecten gravidus n. sp. cated one-fourth to one-third of the length from the sp. indet. posterior end; in the broad area between them, Schizodus sp. B along the plane of commisure, is the small raised Permophorus sp. A? mold of the resilifer and a zigzag line marking the Astartella concentrica (Conrad) ? underside of the taxodont dentition (pi. 1, figs. 2, Sedgwickial sp. indet. Wilkingia terminalis (Hall) 4). The zigzag line is not well enough preserved on any of the specimens to permit a determination of These collections are regarded as late Morrowan in the number of teeth. age; they are associated with foraminifers identi­ Oval anterior and posterior adductor muscle scars fied by Mamet as belonging in Zone 20. Wilkingia are preserved on both valves (pi. 1, fig. 1). The an­ is common to all four collections. terior adductor scars are slightly larger than the posterior ones and occupy the beveled end of the ROSTROCONCHIANS valves. Small paired oval anterior and posterior pedal scars are present, one of each in each valve. This group has recently been made a separate They are located on the dorsum a short distance class of mollusks (Pojeta and others, 1972) ; it is behind and in front of the anterior and posterior exceedingly rare in the Amsden Formation. A small adductor muscle scars (pi. 1, figs. 2, 4). rostroconch fragment, from the Ranchester Member The specimen figured here on plate 1, figures 3-5 at Darwin Peak (colln. 139) in the Pennsylvanian (UM 2657) was illustrated by Bransor and Gregor part of the Amsden, was listed by Blackwelder (1918) as Microdon [Cypricardella]. Two of the (1913, p. 176) on Girty's determination. This speci­ other three specimens, one of which is figured here men is figured in the present report (pi. 4, fig. 22). on plate 1, figures 1, 2, are from a lot (UM 6630) Another specimen, presumably from the Horse­ identified by C. C. Branson (1937) as Uucula sp. shoe Shale Member in the drainage basin of the Nuculopsis sp. A occurs in the s?.me beds as Little Popo Agie River and therefore probably Mis- Paleyoldia amsdenensis (Branson and Greger) but sissippian in age, was described and figured by C. C, is not nearly as abundant. Branson (1937, p. 657, pi. 89, fig. 23) as Conocar- Figured specimens. UM 2657, 6630. dium orientate n. sp. Unfortunately, the specimen Occurrence and number of specimens. Horseshoe was not available to us for study and seems to be Shale Member: collections 36c (1), 3H (3), Fre- lost. mont County, Wyo. PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION OF WYOMING E9

Nuculopsis sp. B northwest Arkansas; this species was illustrated by Plate I, figures 6-9 Morningstar (1922, pi. 10, figs. 22-24). However, Specimens from two localities in the Pennsylvan- the Amsden material is not well enough preserved to ian part of the Amsden are placed in this taxon. make a specific identification. This species is suboval to subtriangular in outline Figured specimens. USNM 174022, 174023. and smaller than Nuculopsis sp. A. The largest Occurrence and number of specimens. Ranches­ specimen (USNM 174018) is a single valve measur­ ter Limestone Member: collection 50 (2), Washakie ing 8.3 mm long, 6.6 mm high, and having a maxi­ County, Wyo. mum convexity of 2 mm. The umbos are opistho- Genus PALEYOLDIA Lintz, 1958 gyral and located about one-third of the length from Paleyoldia amsdenensis (Branson and Greger) the posterior end. The surface ornament consists of Plate I, figures 14-31; figure 1 closely spaced fine concentric growth lines. The zig­ Paleoneilo amsdensensis Branson and Greger, 1918, p. 323, zag trace of the ventral part of the taxodont denti­ pi. 19, figs. 23, 24, text fig. 1. tion and suboval anterior adductor muscle scars are Description. Shell yoldiaform in shape, strongly visible on one internal mold (USNM 174020; pi. 1, rostrate; surface marked with concentric growth figs. 8, 9). lines and vague radial markings (pi. 1, fig. 2^); The known material of this species consists of two beaks opisthogyral, peaks of umbos near midlength, single valves and three articulated internal molds essentially central in younger specimens but offset which are suboval in outline and two internal molds slightly anteriorly in older individuals. of single valves which are subtriangular in outline; Pallial line having shallow posterior ,sinus (pi, 1, the latter are slightly less convex than the suboval fig. 26). Anterior adductor muscle scars large, specimens. The subtriangular specimens have al­ elongate, and quadrate; posterior adductor muscle most straight anterodorsal margins (pi. 1, fig. 7), scars smaller and more oval (pi. 1, figs. 26, 30, SI). whereas the suboval forms have gently convex an­ Accessory muscle scars prominent, consisting of terodorsal margins interrupted by a slight medial paired anterior and posterior pedal scars (pi. 1, fig. angulation (pi. 1, fig. 6). It may be that two species 31) and two (pi. 1, fig. 30) or three (pi. 1, fig. 26) are herein included in Nuculopsis sp. B, but, as both pairs of medial muscle scars in the region of the shapes occur at both localities, we attribute the dif­ umbos. Dentition consisting of anterior and poster­ ferences to individual variation and differences in ior tooth rows interrupted by a resilifer placed be­ configuration between internal and external molds tween beaks (pi. 1, figs. 24, 25) ; anterior tooth row and place them in a single taxon. longer than posterior row. Figured specimens. USNM 174018-174020. Discussion. The description is based on th^ 2 Occurrence and number of specimens. Horseshoe primary types (UM 2665) and 63 additional speci­ Shale Member: collection 53 (2), Johnson County, mens from another University of Missouri collection Wyo. Ranchester Limestone Member: collection 50 (UM 6639). Nine of these specimens are figured in (5), Washakie County, Wyo. this paper. Branson and Greger (1918, p. 323) men­ Superfamily NUCULANACEA Adams and Adams tioned 25 specimens in their collection, but whether Family NUCULANIDAE Adams and Adams Genus PHESTIA Chernyshev, 1951 their unfigured material has been lost or whether it Phestia sp. was incorporated with Branson's later collection Plate 1, figures 10, 11 (UM 6639) is not known. Two specimens assignable to this genus have been The lectotype is herein designated as the speci­ collected from a tan marlstone of Pennsylvania!! age men figured by Branson and Greger (1918) on plate on the west slope of the Bighorn Mountains. One is 19, figures 23, 24; it is figured in this paper on an internal mold (pi. 1, fig. 11) in which the ros­ plate 1, figures 14-16. The dimensions of the le~to- trum is poorly preserved and which is approximately type are: length 14 mm, height 8 mm, and maximum 11 mm long and 5.5 mm high; the second is an ex­ convexity 4.7 mm (both valves slightly gaping) ; it ternal mold which shows the pointed posterior end probably lacks 1 to 1.5 mm of its former length. The and the concentric ornament (pi. 1, fig. 10) and is paralectotype is missing the posterior end, but it 5.8 mm long and 3.1 mm high. No internal struc­ shows more of the surface sculpture than the lecto­ tures are visible on either specimen. type, it was figured by Branson and Greger (1918) The external mold closely resembles Phestia in- as text figure 1 and is here figured on plate 1, fig­ flata (Girty) from the Pennsylvanian (Morrowan) ures 17-19. The measurements of the paralectotype Brentwood Limestone Member of the Bloyd Shale in are: length (incomplete) 12 mm, height 8.7 mm, E10 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING and maximum convexity 5 mm (both valves) ; it Yoldia (Heath, 1937, pi. 10; Driscoll, 19«4, fig. 2) ; probably lacks 3 to 4 mm of its former length. it is most similar to that of the Paleozoic nuculanid The limonitic molds of Paleyoldia amsdenensis Phestia (Driscoll, 1966, figs. 1-5). are the best preserved specimens of any of the Ams- Living species of Yoldia are rapid burrowers den pelecypods we have seen and preserve impres­ (Stanley, 1970) and have large well-developed pedal sions of virtually all of the shell morphology of the muscles (Heath, 1937, pi. 10). .By comparison the species. P. amsdenensis is the first Paleyoldia in pedal muscles of Paleyoldia amsdenensis are small which the musculature is completely known (fig. 1). (fig. 1) and indicate that the animal probably did Although P. amsdenensis is yoldiaform in shape, its not burrow with the same speed and efficiency as musculature differs significantly from that of living modern Yoldia. No separation of the anterior pedal protractor and retractor muscle scars occurs in Paleyoldia, the posterior pedal retractor scars are much smaller than those of Yoldia, and the pallial sinus is only slightly developed. aa The similarity of the muscle scar patterns of Paleyoldia and Phestia suggest a phylogenetic rela­ tionship between these Paleozoic nuculanid genera. appr Because Phestia is the older genus, it is the pre­ sumed ancestor of Paleyoldia. The muscle similarity mm also suggests that Phestia had about the same bur­ rowing ability as Paleyoldia and that increase in speed and efficiency of nuculanid burrowing was largely a post-Paleozoic development. All occur­ rences of P. amsdenensis are from the Mississippian ppr (late Chesterian) part of the formation. According to Puri (1969), Paleyoldia has not previously been reported from rocks older than Pennsylvr.nian. Figured specimens. UM 2665, 6639. Occurrence and number of specimens. Horseshoe Shale Member: collections 27 (3), 29 (1), 36b (2), 36d (63), Fremont County, Wyo.

Paleyoldia sp. Plate 1, figures 12, 13 Two specimens of Paleyoldia, both of which are figured, from the Pennsylvanian part of the Amsden Formation probably represent a second species of the genus. They are from localities on either side of ppr the Bighorn Mountains. The two valves measure 22 and 12 mm in length, 11.7 and 6.8 mm in height, and 4 and 2 mm in greatest convexity, respectively. Al­ though the posterior end is not clearly outlined in either specimen, in both the strongly o^isthogyral beaks are slightly more than halfway back from the anterior end, which contrasts with P. amsdenensis in which the length of the shell posterior to the beaks is equal to or greater than the length anterior 0.5 cm to the beaks. FIGURE 1. Diagrammatic sketch of muscle scar pattern of The smaller of the. .two specimens (pi. 1, fig. 13) Paleyoldia amsdenensis (Branson and Greger). A, Dorsal preserves some of the surface sculpture which con­ view; B, lateral view, aa, anterior adductor; appr, an­ terior pedal protractor and retractor; mm, medial muscles; sists of fine concentric growth lines separated by ppr, posterior pedal retractor; pa, posterior adductor;, wider interspaces. Internal features ar^ not pre­ pi, pallial line; ps, pallial sinus. served on either specimen. PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION OF WYOMING Ell

Figured specimens. USNM 174024, 174025. Genus SEPTIMYALINA Newell, 1942 Occurrence and number of specimens. Horseshoe Septimyalina sp. A Shale Member: collection 53 (1), Johnson County, Plate 2, figures 8-15 Wyo. Ranchester Limestone Member: collection 50 Myalina sancti-ludovici Worthen. Branson and Greger, 1918, (1), Washakie County, Wyo. p. 322, pi. 19, fig. 26. Septimyalina n. sp. Easton, 1962 [part?], p. 92, pi. 12, fig. 24 Subclass ISOFILIBRANCHIA [probably not figs. 23, 25]. Isofilibranchian ? gen. and sp. indet. Description. Shell small, prosocline, inequivalve, Plate 2, figures 1, 2 right valve being slightly less convex than left (pi. Two poorly preserved modioliform internal molds 2, figs. 9, 13, 15). Largest and best preserved speci­ from the Mississippian part of the Amsden Forma­ men (pi. 2, figs. 12-15) was previously figured by tion are here tentatively placed in the Isofili- maximum convexity of 9.2 mm (both valves). Angle branchia. As defined by Pojeta (1971), this subclass between dorsal margin and umbonal ridge (argle includes only the mytilaceans. The Amsden speci­ alpha) approximates 50° and that between dorsal mens have some resemblance to the mytilacean and posterior margins (angle beta) approximates genus Promytilus but may belong to the Myalinidae, 120°. Beaks are strongly prosogyral and shell is some of which are homeomorphic in shape to the moderately thick and strongly lamellose; in some Mytilacea. These specimens are the only possible specimens a weak umbonal septum is present. representatives of the Isofilibranchia so far found Discussion. This species is known from speci­ in the Amsden Formation. mens in the University of Missouri collections that The specimen shown on plate 2, figure 1, is 15 mm came from limonitic shales in the Wind River B?,sin long, 6.5 mm high, and has a maximum convexity probably belonging in the Carlinia amsdeniana Sub- of 2.3 mm. The specimen shown on plate 2, figure 2, zone of Late Mississippian age. The largest speci­ is 13 mm long, 7.5 mm high, and has a maximum men (pi. 2, figs. 12-15) was previously figured by convexity of 2 mm. Branson and Greger (1918, pi. 19, fig. 26) as Mya­ Figured specimens. UW A201, A1275. lina sancti-ludovici and by Easton (1962, pi. 12, fig. Occurrence and number of specimens. Horseshoe 24) as Septimyalina n. sp. The specimens from the Shale Member: collections 28 (1), 31 (1), Fremont Cameron Creek Formation of Montana referred by County, Wyo. Easton (1962) to Septimyalina n. sp. may belong Snbclass PTERIOMORPHIA to a different species than those from the Amslen Order PTERIOIDA Superfamily AMBONYCHIACEA Miller of Wyoming; in the Montana specimens the angle Family MYALINIDAE Frech between the dorsal margin and the umbonal ridge Genus MYALINA de Koninck, 1842 (angle alpha) is greater than the same angle in the Myalina (Myalina) sp. Wyoming specimens. Plate 2, figures 6, 7 The juvenile specimen shown on plate 2, figures One poorly preserved lot of specimens consisting 8, 9, is more strongly prosocline than those shown of 10 left and 3 right valves, from the Neokonin- on plate 2, figures 10, 11, 12-15, angle alpha being ckophyllum hamatilis Zone in the Rawlins hills, is about 36°. As demonstrated by Newell (1942, p. 47, referred to this taxon. The figured right valve (pi. 48), this angle tends to be more acute in the yoking 2, fig. 6) is approximately 19 mm high, 15 mm long, stages of some myalinid species; thus increase, in and has a maximum convexity of 5 mm. The angle the size of this angle is an ontogenetic trend. between the dorsal margin and the umbonal ridge Figured specimens. UM 2658, 6638. cannot be accurately measured because of the poor Occurrence and number of specimens. Horseshoe preservation of the dorsal margin, but it is about Shale Member: collections 36c (1), 36d (6), Fre­ 60°. The shell is moderately thick and is ornamented mont County. ?137 (2), Teton County, Wyo. with concentric growth lines that are particularly prominent near the shell margins. The presence of Septimyalina? sp. indet. a small anterior lobe and the shape of the shell sug­ Plate 2, figure 5 gests that this Pennsylvanian form belongs to Mya­ Another myalinid, from the Pennsylvanian part lina (Myalina). of the Amsden at Hoback Canyon, is represented1 by Figured specimens. USNM 174026, 174027. two left valves, the more complete one of which is Occurrence and number of specimens. Horseshoe figured. The umbonal area and the dorsal margin Shale Member: collection 3 (13), Carbon County, of this specimen are not well preserved; the angle Wyo. between the umbonal ridge and dorsal margin ap- E12 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING proximates 60°. Both specimens have the prominent mm, diagonal dimension 10 mm, and maximum con­ concentric lamellae of Septimyalina but are so poorly vexity 2.3 mm. preserved that one cannot determine whether or not Also referred to this genus is a small left valve an umbonal shelf or an anterior lobe was present. from Cherry Creek, preserved in sandstone, in the They differ from the Mississippian Amsden shells collection of the University of Wyoming (A11123). referred to this genus in their larger size and This specimen has ornamentation of narrow concen­ greater umbonal angle. tric growth lines. Figured specimen. USNM 174028. Figured specimen. USNM 174030. Occurrence and number of specimens. Ranches- Occurrence and number of specimens. Horseshoe ter Limestone Member: collections 130 (1), 131 (1), Shale Member: collection 28 (1), Fremont County, Teton County, Wyo. Wyo. Ranchester Limestone Member: collection 50 (15), Washakie County, Wyo. Superfamily PTERIACEA Gray, 1847 Family PTERINEIDAE Miller Family POSIDONIIDAE Frech Genus CANEYELLA Girty, 1909 Following the suggestion of Stanley (1972) we Caneyella sp. are herein including this family in the Pteriacea Plate 2, figure 4 rather than the Pectinacea where it has tradition­ A unique specimen from a shale in the Washakie ally been placed. Range that occurs 8 feet below a limestone contain­ ing brachiopods of the Car lima amsdeniana Subzone Genus POSIDONIA Bronn, 1828 Posidonia sp. indet. (Mississippian) is referred to the genus Caneyella. Plate 2, figure 3 This right valve is gently convex in the umbonal A small species referred tentatively to Posidonia area but is otherwise nearly flat. A short remnant occurs with Lingula and Streblopteria in a shale of of what is probably the dorsal margin is preserved, Mississippian age in the Washakie Range. In this and the height of the specimen measured down from form the umbo is located near but not at the anter­ this point is 17.5 mm. The surface sculpture con­ ior end of the hinge, and the surface of the shell is sists of relatively narrow concentric undulations ornamented with several shallow concentric undula­ crossed by low radial costae. The costae are only tions. The dimensions of a moderately large speci­ well preserved near the middle of the valve. men are: length 5.0 mm and height 6.5 mm; the This specimen bears a resemblance to Caneyella maximum convexity could not be measured because percostata Girty from the Caney Shale of Okla­ of diagenetic compression of the shell. homa, but because C. percostata disappears in the This form is somewhat similar to Posidonia wapa- Oklahoma-Arkansas section at a lower level in the nuckensis (Girty) from the Caney Shale of south­ Chesterian series than is represented by the Amsden eastern Oklahoma, but the Wyoming material is not beds and because the one specimen we have is poorly adequate for detailed comparison with otHr species. preserved, we are not extending the range of Girty's Figured specimen. USNM 174032. species into Wyoming. Occurrence and number of specimens. Horseshoe Figured specimen. USNM 174029. Shale Member: collection 46 (4), Fremont County, Occurrence and number of specimens. Horseshoe Wyo. Shale Member: collection 46 (1), Fremont County, Superfamily PINNACEA Leach Wyo. Family PINNIDAE Leach Genus AVICULOPINNA Meek, 1864 Genus LEPTODESMA, Hall, 1883 Aviculopinna sp. Leptodesma spp. Plate 2, figures 20-22 Plate 2, figure 19 An elongate, cuneiform, incomplete, articulated A small species of Leptodesma occurs in the Penn- specimen from the Pennsylvanian part of the Ams­ sylvanian part of the Amsden Formation. The speci­ den Formation at Amsden Creek is placed in this mens are all molds which are not well preserved. genus. Although the specimen is only a fragment, it One left valve is figured; it shows the shell shape, has the characteristic shape and concentric mark­ the presence of a posterior auricle and an anterior ings of Aviculopinna. It is most similar to A. pera- lobe, and the highly prosocline nature of the species; cuta (Shumard) which has been reported from the angle between the dorsal margin and the um­ many localities in the Pennsylvanian of the Ameri­ bonal ridge (angle alpha) is about 30°. The dimen­ can midcontinent. sions of this specimen are: length 10 mm, height 6 Figured specimen. USNM 174033. F13 Occurrence and number of specimens. Ranches- ter Limestone Member: collection 52 (1), Johnson ter Limestone Member: collection 67 (1), Sheridan County, Wyo. County, Wyo. Family AVICULOPECTINIDAE Meek and Hayden Subfamily STREBLOCHRONDRIINAE Newell Superfamily PECTINACEA Rafinesque Genus STREBLOPTERIA McCoy, 1851 Family ENTOLIIDAE Korobkov Genus PERNOPECTEN Winchell, 1865 Streblopteria sp. iudet. Pernopecten sp. indet. Plate 2, figure 24 Plate 2, figure 23 The Amsden record of this genus consists of one Three specimens from a granular chert bed of left valve preserved in a grayish-tan shale of Late Pennsylvanian age near the top of the Amsden on Mississippian age in the Washakie Range. The bed the east slope of the Bighorn Mountains belong to is 8 feet below a limestone containing brachiopods the genus Pernopecten. The specimen shown on of the Carlinia amsdeniana Subzone. plate 2, figure 23, is the most complete of the three; This specimen is subcircular, opisthocline, and it is probably a left valve and its dimensions are: measures 14.8 mm long and 13.8 mm high; it is length 14.5 mm, height 17.3 mm, and maximum con­ gently convex but is probably diagenetically com­ vexity 1.2 mm. This shell is gently convex and has pressed. The shell surface is smooth and the auricles two shallow sulci which diverge at an angle of about are incompletely preserved. 60° from the dorsal margin. Figured specimen. USNM 174036. These specimens were identified as Entolium avi- Occurrence and number of specimens. Horseshoe culatum by Girty in a faunal list published by Dar- Shale Member: collection 46 (1), Fremont Courty, ton (1906, p. 34) in his original description of the Wyo. Amsden Formation. In our opinion the material is Subfamily AVICULOPECTININAE Meek and Hayden neither complete enough nor well enough preserved Genus AVICULOPECTEN McCoy, 1851 to assign it to a species. Aviculopecten gravidus n. sp. Figured specimen. USNM 174034. Plate 3, figures 5-7 Occurrence and number of specimens. Ranches- Description. -Shell markedly inequivalve, having ter Limestone Member: collection 52 (3), Johnson strongly convex left valve and nearly flat right County, Wyo. valve, acline to slightly prosocline. Left valve ovr.te, Family PSEUDOMONOTIDAE Newell rounding into auricles; height greater than length; Genus PSEUDOMONOTIS von Beyrich, 1862 in longitudinal profile, curvature is greatest near Pseudomonotis sp. umbo, decreasing slightly toward ventral margin; Plate 2, figure 25 greatest convexity a little above middle. Anterior A unique specimen from the same granular chert auricle set off from main part of valve by weak bed as the previous species is assigned to Pseudo­ diagonal sulcus; posterior auricle not sharply sepa­ monotis. It is a left valve measuring 23.5 mm long, rated from main part of valve but delimited by shal­ 27.5 mm high, 13.5 mm along the dorsal margin, low posterior embayment. and having a maximum convexity of 4.5 mm. Right valve gently convex in umbonal region, The specimen is slightly prosocline and is of mod­ gradually becoming almost flat near margin. Anter­ erate convexity. The anterior auricle is weakly set ior auricle long and separated from body of valve by off from the body of the shell by a rounded diagonal deep byssal notch; posterior auricle not so well de­ concave area, whereas the posterior auricle merges fined, or preserved, but seemingly with very shallow into the body of the shell without a break. concave area of intersection with disk. Surface sculpture consists principally of radial Surface sculpture of both valves consisting of f ne costae which increase in number by intercalation rounded radial costellae separated by subequal in­ and are of somewhat variable strength in an alter­ terspaces. Costellae increase by intercalation on Mt nating pattern; the costae are not absolutely valve; method of increase not possible to determine straight and about 85 occur on this specimen. They on the only right valve because of inadequate pres­ are crossed by fine concentric markings that become ervation. Roughly 125-135 costellae present on left stronger and somewhat lamellose near the posterior valve covering both disk of valve and auricles; num­ margin; some beading is present where the concen­ ber uncertain on right valve; anterior auricle of tric lirae cross the costae. right valve ornamented only by growth lines. Radial Figured specimen. USNM 174035. sculpture crossed by concentric growth lines, some Occurrence and number of specimens. Ranches- of which are quite prominent and indicate periods E14 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIA!*) OP WYOMING of slow growth. Toward margins of left valve, Limestone Member at a locality in the Hoback growth lines become stronger and lamellose. Occa­ Range. sionally, intersecting costellae and growth lines Figured specimens. USNM. 174037A, B. combine to give reticulate appearance to surface. Occurrence and number of specimens. Horseshoe Dimensions (in mm). Shale Member: collection 118 (1), Teton County, USNM 174041 USNM174042 LV (holotype) RV (paratype) Wyo. Height ______44 39 Length ______37 34 Aviculopecten sp. B Convexity _____ 14 4 Plate 2, figures 16-18; plate 3, figure 2 Dorsal margin ____ 24 1 Approximate because incompletely preserved. LV, left valve: RV right This small species has a slightly prosocline shell. valve. Discussion. This species is based on specimens The specimen shown on plate 3, figure 2, is 10.4 mm from a single locality in the Neokoninckophyllum high, 10 mm long, and has a maximum convexity of hamatilis Zone of Pennsylvanian age in the Rawlins 2.5 mm; the dorsal margin is 7.8 mm long. The shell hills. The type lot consists of 12 specimens, all but is unusually convex for its small size. The anterior one of which are left valves. Although none of the auricle is relatively short and is sharply set off from valves is complete, the aggregate lot gives most of the body of the shell; the posterior auricle is longer the essential characters, the most distinctive of than the anterior and is not as abruptly set off from which are the unusual disparity in convexity be­ the body of the shell. tween the two valves and the distinctive fine sculp­ Shell sculpture is well preserved en only one ture which has a reticulate appearance in places. specimen (USNM 174038). It has 10 narrow pri­ The left valve bears some resemblance to that of mary costae having wide, flat to gently concave members of the genus Pseudomonotis, but the right interspaces; the primary costae are more closely valve is that of a typical Aviculopecten. spaced posteriorly than anteriorly. At 3 to 4 mm Types. Holotype USNM 174041, paratypes from the beak, intercalary costae begin to appear USNM 174042-174044. and they increase rapidly in strength. No costae Occurrence and number of specimens. Horseshoe have been seen on the auricles. Concentric growth Shale Member: collection 3 (12), Carbon County, lines are faintly preserved. Two left valves (USNM Wyo. 174039, 174040) preserve some details of the dorsal margin (pi. 2, figs. 16-18) which, considering the Aviculopecten sp. A size of the species, has a wide subtriangular shelf Plate 3, figure 1 extending from the beak to the commissure. This This small species has an acline suboval shell with shelf is marked by horizontal growth lines. the length of the dorsal margin approximately equal Aviculopecten sp. B is found at two Pennsylvan­ to two-thirds of the length of the shell. The most ian localities at either side of the Bighorn Moun­ complete specimen (the larger of the two left valves tains. Of 12 specimens referred to this taxon, 7 are illustrated) measures 9.9 mm high, 8.9 mm long, left valves and the others are also probably left and has a maximum convexity of 1.3 mm; the dorsal valves although they are not complete. The rela­ margin is 6 mm long. The auricles are indistinctly tively sparse radial sculpture and the wide dorsal set off from the main part of the shell; the anterior shelf readily differentiate this form from other auricle has a straight to rounded anterior margin, Amsden Aviculopectens. whereas the posterior auricle has a concave posterior Figured specimens. USNM. 174038-174040. margin and is slightly alate at its dorsal terminus. Occurrence and number of specimens. Horseshoe Surface sculpture consists of about 100 radial Shale Member: collection 53 (3), Johrson County, costellae distributed over the body and auricles Wyo. Ranchester Limestone Member: collection 50 which are separated by wider to subequal flat- (9), Washakie County, Wyo. bottomed interspaces. The costae increase in number by intercalation, but the new elements quickly reach Aviculopecten spp. indet. the strength of the earlier ones so that the shell Plate 3, figures 3, 4 appears evenly costellate. The costellae are crossed Besides the three distinctive species already de­ by fine concentric growth lines. scribed, which are represented by reasonably well Most of our specimens are fragmentary; all of preserved material, several fragmental and poorly them are probably left valves. They came from a bed preserved valves are scattered througl the collec­ of Mississippian age just beneath the Moffat Trail tions, probably representing at least thr^e additional PELECYPODA AND 410STROCONCHIA OF THE AMSDEN FORMATION OF WYOMING E15

species of Aviculopecten. We will consider these in clined at angle of roughly 50° to plane of commis­ order of age from older to younger. sure. Two fragments (USNM 174046, 174047), possi­ Dimensions (in mm). bly belonging to the same species, were found in the uw UW UM A1288 66so Caninia Zone (Moffat Trail Limestone Member) in LV RV *BV RV Height ___-______14.5 13.4 8.2 the Salt River Range at localities about l 1/^ miles Length ______16.7 16.2 9.0 8.4 apart. This species is a medium^sized Aviculopecten Convexity __ 2.9 3.0 (2.2) 2.2 having the left valve ornamented by rather narrow Thickness (both valves) 4.4 costae of alternating strength, separated by wider 1 Ventral part broken off. BV indicates both valves. interspaces. The flat right valve has costae that in­ Discussion. The first two specimens in the to.ble crease by bifurcation, as is typical in this genus. above are from a calcareous sandstone collected in A lot of three weathered specimens (UW A11102) place in the Carlinia am.sdeniana Subzone, 45 feet from the Carlinia amsdeniana Subzone (Horseshoe above the base of the Amsden Formation at Cherry Member) at Cherry Creek belongs in a different Creek. These shells approximate in their dimens'ons species. The shell is convex and ornamented by more and configuration typical specimens of

Cypricardella? sp. indet. 50 (4), Washakie County; 52 (1), Johnson County, Plate 4, figures 8-10 Wyo.

A small articulated and slightly distorted mold Astartella sp. from the Mississippian part of the formation has Plate 4, figures 1-3 prominent, closely spaced concentric rugae and is more or less like Cypricardella in shape. It measures A second species of Astartella is present in the 6 mm high, and has a maximum convexity of 2.8 Mississippian part of the Amsden. This species is mm (both valves flattened). less erect than A. concentrica and it lacl's the con­ centric rugae, being ornamented instead by closely Because of the small size and poor preservation, spaced, fairly even, relatively fine growth lines. It is positive generic assignment of this specimen is not known from only one left valve which measures 17 possible. It is probably a Cypricardella but it could mm long, 11.3 mm high, and has a maximum con­ be a young stage of some other concentrically rugose genus. vexity of 7 mm. Nothing is known of the internal features. Figured specimen. USNM 174060. Astartella sp. has a shape much like Nuculopsis, Occurence. Horseshoe Shale Member: collection however the presence of an escutcheon readily sep­ 20, Fremont County, Wyo. arates Astartella from the latter genus. Family ASTARTIDAE D'Orbigny Figured specimen. USNM 174063. Genus ASTARTELLA Hall, 1858b Occurrence. Horseshoe Shale Member; collection Astartella concentrica (Conrad), 1842 41, Teton County, Wyo.

Plate 4, figures 4-7 Subclass ANOMALODESMATA Nuculites concentrica Conrad, 1842, p. 248, pi. 15, fig. 19. Order PHOLADOMY01DA Posidonia moorei Gabb, 1859 [1860], p. 297; 1860 [1861], p. Superfamily EDMONDIACEA King Family EDMONDIIDAE King 55, pi. 1, fig. 2. Genus EDMONDIA deKoninck, 1841 Edmondia concentrica McChesney, 1859 [1860], p. 55; 1865, Edmondia spp. pi. 2, figs. 21a, b. Astartella concentrica (McChesney). McChesney, 1867 Plate 4, figures 12-16 [1868], p. 43, pi. 2, figs. 21a, b; Keyes, 1894, p. 126; At least three forms of this genus herein treated Plummer and Moore, 1921, pi. 13, figs. 38, 38a, 40, pi. as species are present in the Pennsylvnian part 31, figs. 15, 16; Morgan, 1924, pi. 46, fig. 5. of the Amsden Formation. None of them is well Astartella concentrica (Conrad). Meek, 1875, p. 341; Girty, 1915b, p. 142, pi. 18, figs. 2-9; Price, 1916, p. 725; preserved, and all are represented by very few Morningstar, 1922, p. 241, pi. 13, figs. 11-13; Girty, specimens. They are distinguished by minor differ­ 1927, p. 418, text figs. 1-11; Morse, 1931, p. 319, pi. ences in shape. All three of them are present in one 52, fig. 3; Plummer, 1950, pi. 21, figs. 3a, b; Chow, collection, from a granular chert bed r.igh in the 1951, p. 33, pi. 4, fig. 3; Nicol, 1955, p. 157, text figs. Amsden Formation on the east slope of the Bighorn 2, 3. Mountains (colln. 52) ; this casts some doubt as to Specimens of this widespread and distinctive spe­ whether they actually belong in thre^ different cies are known from several Amsden localities of species. Pennsylvania!! age. Astartella has a recognizable The most widespread of the three forms, repre­ shape and A. concentrica is ornamented with promi­ sented by seven specimens from three localities, is nent concentric rugae that in typical mature speci­ a small elongate Edmondia (pi. 4, figs. 14, 15), oval mens are spaced so that about seven occur in a in shape and similar to E. nebrascensis (Geinitz). space of 5.0 mm. The specimen shown on plate 4, The better preserved of the two figured specimens figures 4, 5, measures 12 mm in length, 9.4 mm in measures: length 7.9 mm, height 5.7 mm, and maxi­ height, and has a maximum convexity of 3.2 mm. mum convexity 1.9 mm. Most of our specimens of this species are fragmen­ A subcircular form (pi. 4, figs. 12, 13) is known tary and not well preserved, but they are readily from a single specimen (colln. 52). It preserves identifiable because of their distinctive ornamenta­ remnants of the adductor muscle scars and is erect, tion (pi. 4, figs. 6, 7). having the umbo projecting well above the dorsal Figured specimens. USNM 174061, 174062. margin. Measurements of this specimen are: length Occurrence and number of specimens. Horseshoe about 15 mm, height 13.8 mm, and maximum con­ Shale Member: collections ?3 (1), Carbon County; vexity 6 mm. 53 (2), Johnson County, Wyo. Ranchester Lime­ The third form (pi. 4, fig. 16), also known from stone Member: collections 40 (2), Fremont County; one specimen, from the same locality as the last, is PELECYPODA AND ROSTROCONCHIA OF THE AMSDEN FORMATION OF WYOMING E19 elongate quadrate and preserves some of the con­ Occurrence. Horseshoe Shale Member; collection centric surface ornamentation. It measures 21.5 mm 22, Fremont County, Wyo. in length, about 17 mm in height, and has a maxi­ Genus SEDGWICKIA McCoy, 1844 mum convexity of 6.3 mm. Sedgwickia? sp. indet. Figured specimens. USNM 174064-174067. Plate 4, figures 23, 24 Occurrence and number of specimens. Ranches- One highly weathered and incomplete articulated ter Limestone Member: collections 40 (1), Fremont internal mold, from the Pennsylvanian part of the County; 50 (2), Washakie County; 52 (6), Johnson Amsden, has the general outline of some species County, Wyo. placed in Sedgwickia by Meek and Hayden (1865) and Hind (1899) and is here tentatively referred Superfamily PHOLADOMYACEA Gray Family GRAMMYSIIDAE Miller to that genus. It measures about 55 mm in length, Genus SPHENOTUS Hall, 1885 32.4 mm in height, and has a maximum convexity Sphenotus sp. of 19.5 mm (both valves). Plate 4, figures 17, 18 Figured specimen. USNM 174069. The figured specimen' has the shape, posterior Occurrence. Horseshoe Shale Member: ccSec­ auricle, and umbonal carina typical of Sphenotus; tion 5, Carbon County, Wyo. it comes from the Carlinia amsdeniana Subzone at Family PHOLADOMYIDAE Gray Darwin Peak. It is a small internal mold which Genus WILKINGIA Wilson, 1959 measures 14.6 mm long, 7.1 mm high, and 3.5 mm in Wilkingia terminalis (Hall) maximum convexity. Another example, a poorly Plate 4, figures 26-30 preserved articulated internal mold from the same Allorisma terminalis Hall, 1852, p. 413, pi. 2, figs. 4a, b. part of the formation in Wind River Range (UM Allorisma terminate (Hall). Girty, 1903, p. 437, 438, pi. 9, figs. 4-6 (for synonymy prior to 1903); 1909, p. 90; 12791), is referred tentatively to this taxon. Price, 1914, p. 527; 1921, p. 784; Morningstar, 1922, Difference of opinion has existed for some time p. 234, pi. 13, fig. 15; Morse, 1931, p. 318, pi. 51, figs. 2. (Hind, 1900; Driscoll, 1965; Pojeta, 1969; Newell Allorisma subcuneatum (Meek and Hayden). Barbour, 1903, and LaRocque, 1969) as to whether the genus pi. 2, fig. 18; Raymond, 1910, p. 158, pi. 27, figs. 5, 6; Sphenotus Hall is separable from Sanguinolites 1911, p. 98, pi. 6, fig. 5; Plummer and Moore, 1921, pi. 24, fig. 18. McCoy. We have followed Driscoll (1965) in this Allorisma terminate (Hall). Mark, 1911, pi. 10, fig. 10; regard and have treated the two as separate genera. Morgan, 1924, pi. 46, figs. 3, 3a; Butts, 1926, p. 200, In general, forms assigned to Sphenotus have a less pi. 66, fig. 16; French, 1940, p. 328, pi. 3, fig. 23; prominent concentric sculpture than those placed in Shinier and Shrock, 1944, p. 414, pi. 165, figs. 10, 11; Sanguinolites. Branson, 1948, p. 563; Chronic, 1952, p. 146, 147, pi. 9, figs. 4a-c; Chow, 1951, p. 31, pi. 3, figs. 17a-c; Figured specimen. USNM 174068. Burk, 1954 [part], p. 14, 15, pi. 1, figs. 39, 40 [not Occurrence and number of specimens. Horseshoe fig. 38]; Mudge and Yochelson, 1962, p. 90, pi. 16, figs. Shale Member: collections ?36d (1), Fremont 5, 6. County; 137 (1), Teton County, Wyo. A number of specimens from several localities, both in the Mississippian and Pennsylvanian parts Genus SANGUINOLITES McCoy, 1844 of the Amsden Formation, are referred to this Sanguinolites sp. ubiquitous and long-ranging species. None is well Plate 4, figures 19-21 preserved but several show the characteristic phola- Allorisma terminate (Hall). Burk, 1954 [part], p. 14, 15, pi. domyiform shape with subparallel dorsal and ven­ 1, fig. 38 [not figs. 39, 40]. tral margins and the ornament of prominent con­ A single dorsoventrally crushed articulated limo- centric rugae. The specimen shown on plate 4, figure nitic mold from the Mississippian part of the Ams- 26, has the following measurements: length 39 mm, den is here placed in the genus Sanguinolites. It has height 20.1 mm, and maximum convexity 7.8 mm. prominent concentric ornament from the umbonal The specimens figured in this paper are from the ridge across the anterior part of the shell; the Pennsylvanian part of the formation. Burk (1954, strength of the ornament is reduced posterodorsal pi. 1, figs. 39, 40) has previously figured specimens to the umbonal carina. In this way it is similar to from near the top of the Mississippian part. species placed in Sanguinolites by Hind (1900) and Figured specimens. USNM 174070, 174071. Pojeta (1969). Measurements of the specimen were Occurrence and number of specimens. Horseshoe not made because of its distorted condition. Shale Member: collections 1 (2), 2 (1), 3 (8), 5 Figured specimen. UW IT-237. (3), Carbon County; 36e (1), 43 (4), Frenont E20 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING County, Wyo. Ranchester Limestone Member: col­ Wyoming and its fauna: Geol. Soc. America Bull., v. lection 50 (7), Washakie County, Wyo. 29, no. 6, p. 309-327, pis. 18, 19. Bronn, H. G., 1828, Posidonia becheri eine neue fossile Mu- Wilkingia sp. schel der Uebergangs-Periode: Leonhard Taschenbuch Plate 4, figure 25 fur die gesammte Mineralogie, Zeitschrift fur Miner- alogie, neue folge, v. 1, no. 4, p. 262-269, pi. 2. Allorisma terminate (Hall). Burk, 1954 [part], p. 14, 15 1835-37, Lethaea Geognostica oder Abbildungen und [not pi. 1, figs. 38-40]. Beschreibungen der fur die Gebirgs-Formation bezeich- A second species of Wilkingia is represented by nendsten Versteinerungen, v. 1, 544 p., 47 p1?. (text and one reasonably complete and two fragmentary plates bound separately) : Stuttgart, E. Schweizerbart. limonitic molds from the Mississippian part of the Burk, C. A., 1954, Faunas and age of the Amsden formation Amsden Formation at South Pass in the Wind in Wyoming: Jour. Paleontology, v. 28, no. 1, p. 1-15., pi. 1. River Range. In general outline this species is simi­ Butts, Charles, 1926, Geology of Alabama the Paleozoic lar to W. terminal-is but differs in that secondary rocks: Alabama Geol. Survey Spec. Rept. 14, p. 41-230, concentric rugae are intercalated between the pri­ 74 pis., 4 text figs. mary ones about one-fourth of the way back from Ohavan, Andre, 1954, Les Pleurophorus et genres voisins: Cahiers Geol. Thoiry, no. 22, p. 200. the anterior edge. These secondary rugae do not Chernyshev, B. I., 1951, Semeystvo Ledidae iz Kamennou- cross the entire shell surface but die out anteriorly. gol'nykh otlozheniy SSSR: Trud., Akad. Nauk Ukrain, The figured specimen measures 18.2 mm long, about SSR, Kiev, Ser. Strat. i Paleont., v. 2, 40 p., 2 pis. 8 mm high, and has a maximum convexity of 2 mm. Chow, M. M., 1951, The Pennsylvanian Mill Creek limestone Figured specimen. UW IT-240. in Pennsylvania: Pennsylvania Geol. Survey, 4th ser., Occurrence and number of specimens. Horseshoe Bull. G26, 36 p., 4 pis., 3 text figs. Chronic, Halka, 1952, Molluscan fauna from the Permian Shale Member: collection 22 (3), Fremont County, Kaibab formation, Walnut Canyon, Arizona: Geol. Soc. Wyo. America Bull., v. 63, no. 2, p. 95-165, 11 pis., 15 text figs. Conrad, T. A., 1842, Descriptions of new species of organic Class ROSTROCONCH1A Family CONOCARDIIDAE Miller remains belonging to the Silurian, Devonian, and Car­ Genus CONOCARDIUM Bronn, 1835 boniferous systems of the United States: Acad. Nat. Sci. Philadelphia Jour., v. 8, pt. 2, p. 235-280, pis. 13-17. "Conocardium" sp. indet. Darton, N. H., 1906, Geology of the Bighorn Mountains: Plate 4, figure 22 U.S. Geol. Survey Prof. Paper 51, 129 p., 47 pis., 14 text figs. In the Amsden collections available to us, rostro- Driscoll, E. G., 1964, Accessory muscle scars, an aid to conchians are represented by a single incomplete protobranch orientation: Jour. Paleontology, v. 38, no. 1, specimen from the Mississippian part of the for­ p. 61-66, pi. 16. mation which has the general aspect of forms pres­ 1965, Dimyarian pelecypods of the Mississippian ently assigned to the genus Conocardium. The class Marshall sandstone of Michigan: Palaeontographica Rostroconchia is currently under revision by Pojeta Americana, v. 5, no. 35, 64-128, pis. 7-18. and Runnegar. -1966, Morphology and evolution of certain Paleozoic Nuculanidae from the mideontinental United States: Figured specimen. USNM 182074. [Czechoslovakia] Narod. Muz. Praze Sbornik, ser. B, v. Occurrence and number of specimens. Ranches­ 22b, no. 1, p. 1-26, pis. 1-4. ter Shale Member: collection 139 (1), Teton Easton, W. H., 1962, Carboniferous formations and faunas County, Wyo. of central Montana: U.S. Geol. Survey Prof. Paper 348, 126 p., 14 pis. REFERENCES CITED French, E. M., Jr., 1940, Characteristic fossils of Maryland: Barbour, E. 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C., ed., Treatise on invertebrate America and Kansas Univ. Press, p. N129-N205. paleontology, pt. N, Mollusca 6, Bivalvia, v. 2: New Keyes, C. R., 1891, Fossil faunas in central Iowa: Acad. York, Geol. Soc. America and Kansas Univ. Press, p. Nat. Sci. Philadelphia Proc. 1891, p. 242-265. N819-N823. 1894, Paleontology of Missouri, part 2: Missouri Geol. Nicol, David, 1955, Morphology of Astartella, a primitive Survey, v. 5, 266 p., pis. 33-56. heterodont pelecypod: Jour. Paleontology, v. 29, no. 1, p. Koninck, L. G. de, 1841-44, Description des animaux fossiles 155-158, 4 text figs. qui se trouvent dans le terrain Carbonifere de Belgique, p. 59-146, pis. 1-5, H: Liege, H. Dessain. Plummer, F. B., 1950, The Carboniferous rocks of the Llano Lintz, Joseph, Jr., 1958, The fauna of the Ames and Brush region of central Texas: Texas Univ. Pub., no. 4329, Creek shales of the Conemaugh formation of western 170 p., 22 pis., 4 charts, 14 figs. Maryland: Jour. Paleontology, v. 32, no. 1, p. 97-112, pi. Plummer, F. B. and Moore, R. C., 1921, Stratigraphy of the 16. Pennsylvanian formations of north-central Texas: Texas McChesney, J. H., 1859, Descriptions of new species of fossils Univ. Bull., no. 2132, 237 p., 27 pis., 19 text figs. from the Paleozoic rocks of the Western States: Ex­ Pojeta, John, Jr., 1969, Revision of some of Girty's inverte- E22 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING

brate fossils from the Fayetteville Shale (Mississippian) Guidebook 10th Ann. Field Conf. 1955: p. 60-63, 1 cor­ of Arkansas and Oklahoma Pelecypoda: U.S. Geol. Sur­ relation chart. vey Prof. Paper 606-C, p. 15-24, pis. 3, 4. Shimer, H. W., and Shrock, R. R., 1944, Inder fossils of -1971, Review of Ordovician pelecypods: U.S. Geol. North America; New York, John Wiley and Sons, 837 p. Survey Prof. Paper 695, 46 p., 20 pis. Stanley, S. M., 1968, Post-Paleozoic adaptive radiation of Pojeta, John, Jr., Runnegar, Bruce, Morris, N. J., and New­ infaunal bivalve molluscs a consequence of mantle fu­ ell, N. D., 1972, Rostroconchia a new class of bivalved sion and siphon formation: Jour. Paleontology, v. 42, no. mollusks: Science, v. 177, no. 4045, p. 264-267, 3 text figs. 1, p. 214-229, 13 figs. Price, W. A., 1914, Notes on the paleontology of Preston 1970, Relation of shell form to life habits of the Bi­ County fossil fauna of the Conemaugh rocks: West valvia (Mollusca) : Geol. Soc. America Mem. 125, 296 p., Virginia Geol. Survey, Preston County, Rept., p. 472- 40 pis. 553, pis. 42, 43. -1972, Functional morphology and evolution of byssally 1916, Notes on the paleontology of Raleigh, Wyoming, attached bivalve mollusks: Jour. Paleontology, v. 46, no. McDowell, and adjacent counties: West Virginia Geol. 2, p. 165-212, 34 figs. Survey, Raleigh County, Rept., p. G63-734, pis. 30, 31. Verneuil, P. E. P. de, and Murchison, R. I., 1844, Note sur -1921, Notes on the paleontology of Nicholas County les equivalents du systeme permien en Europe, suivie Invertebrate fossils from the Pottsville series: West Vir­ d'un coup d'oeil general sur 1'ensemble de ses fossiles, ginia Geol. Survey, Nicholas County, Rept, p. 751-788, et d'un tableau des especes: Soc. Geol. France Bull., 2d 2 pis., 1 text fig. ser., v. 1, p. 505. Puri, H. S., 1969, Family Nuculanidae, in Moore, R. C., ed., Weller, Stuart, 1916, Description of a Ste. Genevieve lime­ Treatise on invertebrate paleontology, pt. N, Mollusca 6, stone fauna from Monroe County, Illinois: Chicago Bivalvia, V. 1: New York Geol. Soc. America and Kansas Univ. Walker Mus. Contr., v. 1, no. 10, p. 243-264, pis. Univ. Press, p. N235-N241. 15-19. Raymond, P. E., 1910, A preliminary list of the fauna of the Wilson, R. B., 1959, Wilkingia gen. nov. to replace Allorisma Allegheny and Conemaugh series in western Pennsyl­ for a genus of upper Paleozoic lamellibranchs: Palaeon­ vania: Carnegie Mus. Annals, v. 7, no. 1, p. 144-158, tology, v. 1, pt. 4, p. 401-404, pi. 71. pis. 24-28. Winchell, Alexander, 1865, Descriptions of new species of 19.11, A preliminary list of the fauna of the Allegheny fossils, from the Marshall group, and its supposed and Conemaugh series in western Pennsylvania: Penn­ equivalent in other States * * *: Acad. Nat. Sci. Phila­ sylvania Topog. Geol. Survey Comm. Rept. 1908-10, p. delphia Proc. 1865, p. 109-133. 81-98, pis. 3-6. Worthen, A. H., 1890, Description of fossil invertebrates: Sando, W. J., Gordon, Mackenzie, Jr., and Dutro, J. T., Jr., Illinois Geol. Survey, v. 8, p. 69-154, pis. 10-28. 1974, Stratigraphy and geologic history of the Amsden Worthen, A. H., 1884, Descriptions of two new species of Formation (Mississippian and Pennsylvania!!) of Wyo­ Crustacea, fifty-one species of Mollusca, and three spe­ ming: U.S. Geol. Survey Prof. Paper 848-A. (In press.) cies of crinoids, from the Carboniferous formations of Shaw, A. B., 1955, The Amsden formation in southwestern Illinois and adjacent states: Illinois State Mus. Nat. and south-central Wyoming in Wyoming Geol. Assoc. History, Bull. 2, 27 p. INDEX [Italic page numbers indicate both major references and descriptions]

Page Page Page Moffat, Trail section E5 Mollusca ---- 8 moorei, Posidonia ....-.. _--- ______18 Darwin Peak section--- ____- E6 abruptus, Schizodus depressus ------E15 morroivensis, Schizodus ....--...- 16 Darwin Sandstone Member -- 4 affinis, Schizodus ___ . ---- 5, 7, 15; pi. 3 Myalina ...... ------3 ,5,11 depressus, Schizodus __--_ 2, 5, 7, 15, 16; pi. 3 Allorisma subcuneatum . -____-_ ._--_ 19 sancti-ludovici ...... -..------1,11 abruptus, Schizodus ______-__- ___ 15 terminate ...... ------2,19,20 (Myalina) ...... ------11 Diaphragmus nivosus - __-______6 terminalis .... ------_-_ 19 sp _ _ - B,8.« ;pl. 2 Dolabra alpina ....------____.--_____ 16 alpina, Dolabra . ------16 Myalinidae _------3, 11 Schizodus ...... 16 Myophoriidae ___-___--___ - -- 3,15 alpinus, Schizodus ...... - 5,7, 16; pi. 3 E Ambonychiacea 11 N amsdenensis, PaleoneUo ...... 1, 9 Edmondia ...... 2,3,8,18 Paleyoldia ...... 1, 5, 7, 8, 9, 10; pi. 1 concentrica ...--,-...... -...... 18 nebrascensis, Edmondia ...... --... 18 Anomalodesmata --- ______2, 18 nebrascensis ...... 18 Anthracospirifer iveller-shawi Zone _-_ 4 sp ______5, 7, 8, iS;pl. 4 NeokoninckophyUum hamatUis 13, 15 Antiquatonia blackwelderi Zone ___ . 4, 7 Edmondiacea ______18 Zone -- 4,8,11, 6 Astartella ...... ------...... 3,18 Edmondiidae --_----__-_----_ -- 3, 18 nivosus, Diaphragmus _-- --- Nucula sp. C ------_____ concentrica ...... -. 5, 7, 8, 18; pi. 4 Entoliidae ______- 3,13 sp ______------__ 5, 6, 18; pi. 4 Entolium ___._--____-.-__ ___-_ 2 sp ______-_____------_-_-___----_ Astartidae 3,18 aviculatum ______13 Nuculacea .-___- _-- aviculatum, Entolium ...... 13 Nuculanacea ------Aviculopecten ...... 3,6,13,14,16 Nuculanidae ______gravidus ...... 5, 8, 13; pi. 3 Nuculidae --- ___ --- -- 3, 8 sp. A ._--.- . 5, U;pl. 3 Nuculites concentrica ...... - - 18 sp. B ______5, 7, 14; pis. 2, 3 Faunal diversity Nuculoida _-_------8 sp ___-__ . --- 5, 7, Ik, pi. 3 Nuculopsis ...... ------3 8,18 Aviculopectinidae --- 3,13 sp. A ______----- 1,2,5,7,5,9 Aviculopectininae 13 sp. B -_ 5,7,9 pi. 1 Aviculopinna ...... ------3,12 Geographic and stratigraphic occurrence peracuta ...... 12 of the pelecypods __ k sp ______5, 7, 12; pi. 2 Grammysiidae -______-__ 3, 19 gravidus, Aviculopecten ...... 5, 8, 13; pi. 3 oblonga, Cypricardella -...... 17 oblongus, Microdon ...... 1,8,17 H orientale, Conocardium ...... 2, 8 Otter Shale 17 Bighorn Mountains _-_ .______13,18 Bloyd Shale ______9 Hale Formation of Arkansas . _ 16 Brentwood Limestone Member _____ 9 Heath Formation ______--_-- 17 Heath Shale of Montana _.______6 Heteroconchia ______2, 15 Palaeotaxodonta 2, 8 Hoback Canyon _--_-.-----_-__ _._ 5, 7 PaleoneUo amsdenensis ...... 1, 9 Horseshoe Shale Member ___.______4,5,6 Paleyoldia ...-...... 3,9,10 Caney Shale of Oklahoma ... 12 amsdenensis ...... 1, 5, 7, 8, 9, 10; pi. 1 Caneyella ...... 3,12,17 sp ______5, 7, 10; pi. 1 percostata ...... 12 Parallelodontidae __ __ 3 sp ... . _ 5, 7, 12; pi. 2 Pectinacea __- __ - 13 Caninia Zone _---__--______4, B, IB inflata, Phestia .... ______9 Pelecypoda -_ -- .-_--_-.. 5, 8 Isofilibranchia ______2,11 Carditacea ______-_.-___-______16 Pennsylvanian fauna ----- . ----- 7 Isofilibranchian _..______3, 5, 7, 11; pi. 2 Carlinia amsdenia.no, peracuta, Aviculopinna ... ______12 Subzone --._ 4, 7, 11, 12, 13, 15, 19 percostata, Caneyella - - _._-______12 Composite poposiensis Subzone __._... 4 Permophoridae ------. ______3,16 Composition of the fauna __.______2 Permophorus ______.-_-_____- 2,3,16,17 concentrica, Astartella ..... _ 5, 7, 8, 18; pi. 4 Leptodesma ...... ______3, 12 sp. A ______3, 5, 7, 8, 16; pi. 3 Edmondia ...... ______18 sp ______5, 7, 12; pi. 2 Pernopecten ...... _--_-_-.-_ 2,3,13 Nuculites ...... _____ 18 Lingula ...... 7, 12 sp ____--.______.. 5, 8, IS; pi. 2 Conocardiidae -__.__ ._____ 20 Phestia ...... 3,9,10 Conocardium ______.______20 inflata ...... 9 orientate ...... 2, 8 M sp --. _-_ 5, 7, 9; pi. 1 sp 5, 20; pi. 4 Pholadomyacea _------___------_ 19 Covey Cutoff section --____--_.__ 5 Mesolobus Zone ______4 Pholadomyidae _--______.__-_-__ 3, 19 Crassatellacea _.__-___..____.__ 17 Microdon ______8 Pholadomyoida ------_-..-__..___ 18 Crassatellidae ...______3,17 oblongus ...... ----.-...... 1,8,17 Pinnacea __-______12 Cypricardella ...... 3, 8, 17, 18 Mississippian fauna -______5 Pinnidae ______-_.____ 3, 12 oblonga ...... _._ 17 Mississippi-Pennsylvanian boundary__ 3 Pleurophorus ...... __.______2,17 sp ___ 1, 5, 7, 17, 18; pi. 4 Moffat Trail Limestone Member ____ 4, 5, 6 sp ______16,17 E23 E24 INDEX

Page Page Page Posidonia __-__ E3, 12 Sanguinolites ...... -.._ E3, 19 moorei ______._ -______18 sp ______2, 5, 7, 19; pi. 4 wapanuckensis ______12 Schizodus ...... 3 ,15, 16 terminate, Allorisma ...... E2,19, 20 sp ______5, 1, 12; vl. 2 affinis .-.-.. ------__ ---- 5, 7, 15; pi. 3 terminalis, Allorisma ...... 19 Posidoniidae 3, 12 alpina ------16 Wilkingia ...... __ 2, 3 5, 7, 8, 19; pi. 4 Promytttus ...... - 11 alpinus ...... 5, 7, 16; pi. 3 Trigoniacea ______.___-_--_ 15 Pseudomonotidae ______--______3, 13 depressus ...... 2, 5, 7, 15, 16; pi. 3 Trigonioida -_-_---.--_----- __._ 15 Pseudomonotis ...... 3, 13, 14 abruptus ...... 15 sp ______5, 8, 13; pi. 2 morrowensis .. ------16 Pteriacea -__-______.___ 12 sp. A ______-______6, 7, ifi;pl. 8 Pterineidae ______-._____ 3,12 sp. B --___------_--.- 5, 8, 16; pi. 3 Pterioida ______11 sp ______-__ -__ __ 2,15 Veneroida 16 Pteriomorpha ______2 Sedgwickia ------3, 19 Ptefriomorphia _-___-__-______11 sp - _.______-___ 5, 8, i9;pl. 4 W Septimyalina ...... ___ 3, 11 R sp. A __-______5,7, 11; pi. 2 wapanuckensis, Posidonia ...... 12 sp ______1,5, 7, 11; pi. 2 Ranchester Limestone Member _ 4, 7 Washakie Range __-____._____ 12 Rawlins hills ______11, 15 Sphenotus ...... 3,19 Wilkingia ... ______3,19,20 sp _____.______5, 7, 19; pi. 4 Relation to Mississippian-Pennsylvanian terminalis ______2, 3 5, 7, 8, 19; pi. 4 Boundary _.______. 3 Ste. Genevieve Limestone --._-__.-_ 15 sp ______5, 7, 20; pi. 4 Rostroconchians ______2,5,3,20 Stratigraphic considerations .__ ----- 4 Streblochrondriinae ---_ -__-___ 13 Streblopteria ...... 3, 12,13 sp .______5, 1,13; pi. 2 sancti-ludovici, Myalina __._.-. -- 1,11 subcuneatum. Allorisma ...... 19 Yoldia 10

U.S. GOVERNMENT PRINTING OFFICE: 19VB -5S5 474/93 PLATES 1-4

Contact photographs of the plates in this report are available, at cost, from U.S. Geological Survey Library, Federal Center, Denver, Colorado 80225. PLATE 1

FIGURES 1-5. Nuculopsis sp. A (p. E8). 1,2. Left valve showing adductor muscle scars and dorsal view showing pedal muscle scars and trace of the taxodont dentition (X 3). UM 6630, collection 36d. 3-5. Right valve, dorsal view, and left valve showing adductor muscle scars, pedal muscle scars, and filling of resilifer (X 2). UM 2657, collection 36c. 6-9. Nuculopsis sp. B (p. E9). Collection 50. 6. Right valve (X 2). USNM 174018. 7. Left valve (X 2). USNM 174019. 8. 9. Right valve showing anterior adductor muscle scar and dor­ sal view showing trace of taxodont dentition (X 3). USNM 174020. 10,11. Phestia sp. (p. E9). 10. Rubber cast of right valve mold showing ornament and shape of rostrum (X 4). USNM 174022, collection 50. 11. Right valve (X 2). USNM 174023, collection 50. 12,13. Paleyoldia sp. (p. E10). 12. Left valve (X 1). USNM 174024, collection 50. 13. Right valve (X 2). USNM 174025, collection 53. 14-31. Paleyoldia amsdencnsis (Branson and Greger) (p. E9). 14-16. Dorsal (anterior end up) (X 4), left valve, (X 2), and right valve (X 2), views of lectotype. UM 2665, collection 36b. 17-19. Left valve, dorsal (anterior end down), and right valve views (X 2), of paralectotype. UM 2665, collection 36b. 20. Left valve (X 3). UM 6639, collection 36d. 21,22. Dorsal (anterior end up) (X 10), and right valve (X 5), views. UM 6639, collection 36d. 23,24. Left valve (X 3), and dorsal (anterior end Tip) (X 6), views, showing some muscle scars and trace of the taxodont den­ tition. UM 6639, collection 36d. 25,26. Dorsal (anterior end up) (X 7), and left valve (X 9), views, showing trace of taxodont dentition, pallial line, pallial sinus, and most other muscle scars. UM 6639, collection 36d. 27,28. Dorsal (anterior end down) (X 3), and left valve (X 6), views. UM 6639, collection 36d. 29. Left valve (X 3). UM 6639, collection 36d. 30,31. Right valve (X 5), and dorsal (anterior end down) (X 6), views showing muscle scars. UM 6639, collection 36d. GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-E PLATE 1

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14

PALAEOTAXODONTA PLATE 2

FIGURES 1,2. Isofilibranchian? gen. and sp. indet. (p. Ell). 1. Left valve (X 2), UW A1275, collection 31. 2. Right valve (X 2), UW A201, collection 28. 3. Posidonia sp. indet. (p. E12). Left valve (X 4). USNM 174032, collection 46. 4. Caneyella sp. (p. E12). Right valve (X 1). USNM 174029, collection 46. 5. Se-ptimyalinat sp. indet. (p. Ell). Left valve (X 1). USNM 174028, collection 131. 6,7. Myalina (Myalina) sp. (p. Ell). Collection 3 (X 1). 6. Rigth valve. USNM 174026. 7. Left valve. USNM 174027. 8-15. Septimyalina sp. A (p. Ell). 8,9. Left valve and dorsal views (X 3). UM 6638, collection 36d. 10, 11. Anterior and right valve views (X 2). UM 6638, collection 36d. 12-15. Right valve, dorsal, left valve, and anterior views (X 2). UM 2658, collection 36c. 16-18. Aviculopecten sp. B (p. E14). Collection 50 (X 3). 16. Left valve. USNM 174039. 17,18. Anterior view of rubber cast showing dorsal margin shelf extending from beak to commissure, and oblique lateral view also showing shelf. USNM 174040. 19. Leptodesma sp. (p. E12). Left valve (X 4). USNM 174030, collection 50. 20-22. Avicuiopinna sp. (p. E12). Dorsal (X 1), left valve (X 2), and dorsal (X 2) views. USNM 174033, collection 67. 23. Pernopecten sp. indet. (p. E13). Left valve (X 2). USNM 174034, collection 52. 24. Streblopteria sp. indet. (p. E13). Left valve (X 2). USNM 174036, collection 46. 25. Pseudomonotis sp. (p. E13). Left valve (X 1). USNM 174035, collection 52. GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-E PLATE

22 23 24 25 ISOFILIBRANCHIA? AND PTERIOMORPHA PLATE 3

FIGURE 1. Aviculopecten sp. A (p. E14). Two left valves (X 3). USNM 174037A, B, collection 118. 2. Aviculopecten sp. B (p. E14). Left valve (X 3). USNM 174038, collection 50. 3,4. Aviculopecten spp. indet. (p. E14). Enlargement showing ornament (X 2) and entire valve (X 1). USNM 174045, collection 53. 5-7. Aviculopecten gravidus n. sp. (p. E13). Collection 3 (X 1). 5. Holotype showing shape and ornament of left valve. USNM 174041. 6. Paratype showing shape of right valve. USNM 174042. 7. Paratype showing left valve. USNM 174043. 8, 9. Schizodus sp. A (p. E16) . Right valve and dorsal (anterior end down) views (X 2). UM 6637, collection 36a. 10-13. Schizodus cf. S. depressus Worthen (p. E15). 10,11. Dorsal (anterior end down) and right valve views (X 3). UM 6630, collection 36d. 12. Right valve (X 3). USNM 174048, collection 20. 13. Left valve (X 2). UW A11121, collection 28. 14. Schizodus sp. B (p. E16). Right valve (X 1). USNM 174052, collection 3. 15,16. Schizodus aff. S. affinis Herrick (p. E15). Two right valves (X 2). USNM 174049, 174050, collection 50. 17. Schizodus alpinus (Hall)? (p. E16). Right valve (X 1). USNM 174051, collection 53. 18-23. Permophorus sp. A (p. E16). (X 2). 18. Left valve. USNM 174053, collection 53. 19. Right valve. USNM 174054, collection 52. 20. Right valve. USNM 174059, collection 159. 21. Right valve. USNM 174056, collection 50. 22. Left valve. USNM 174057, collection 50. 23. Left valve. USNM 174055, collection 52. GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-E PLATE 3

20 21 22 PTERIOMORPHA AND HETEROCONCHIA PLATE 4

FIGURES 1-3. Astartella sp. (p. E18). Dorsal, anterior, and left valve views (X2). USNM 174063, collec­ tion 41. 4-7. Astartella concentrica (Conrad) (p. E18). Collection 50 (X 2). 4, 5. Right valve and dorsal views. USNM 174061. 6, 7. External mold right valve and rubber cast of mold showing ornament. USNM 174062. 8-10. Cypricardellal sp. indet. (p. E18). Right valve, anterior, and left valve views (X 3). USNM 174060, collection 20. 11. Cypricardella sp. (p. E17). Left valve (X 2). UM 2657, collection 36c. 12,13. Edmondia sp. (p. E18). Left valve and dorsal views showing adductor muscle scars (X 2). USNM 174066, collection 52. 14,15. Edmondia sp. (p. E18). 14. Right valve (X 2). USNM 174065, collection 50. 15. Right valve (X 2). USNM 174064, collection 52. 16. Edmondia sp. (p. E18). Right valve (X 1). USNM 174067, collection 52. 17,18. Sphenotus sp. (p. E19). Left valve and dorsal views (X 2). USNM 174068, collection 137. 19-21. Sanguinolites sp. (p. E19). Left valve, dorsal, and right valve views (X 2). UW IT-237, col­ lection 22. 22. "Conocardium" sp. indet. (p. E20). Fragment of left valve (X 3). USNM 182074, collection 139. 23,24. Sedgwickial sp. indet. (p. E19). Right valve and dorsal views (X 1). USNM 174069, collection 5. 25. Wilkingia sp. (p. E20). Left valve (X 2). UW IT-240, collection 22. 26-30. Wilkingia terminal (Hall) (p. E19). 26. Left valve (X 1). USNM 174071, collection 50. 27-30. Anterior, right valve, dorsal, and left valve views (X 1). USNM 174070, collection 5. PROFESSIONAL PAPER 848-E PLATE 4

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30 HETEROCONCHIA, ANOMALODESMATA, AND ROSTROCONCHIA