Upper Cretaceous Gastropods From the Pierre Shale at Red Bird, Wyoming GEOLOGICAL SURVEY PROFESSIONAL PAPER 393-B Upper Cretaceous Gastropods From the Pierre Shale at Red Bird,Wyomin By NORMAN F. SOHL STRATIGRAPHY, PALEONTOLOGY, AND SEDIMENTATION OF A CLASSIC REFERENCE LOCALITY OF THE PIERRE SHALE GEOLOGICAL SURVEY PROFESSIONAL PAPER 393-B A discussion of the Pierre Shale gastropod fauna, including a description of 23 named species, occurring in the Red Bird section UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director For sale by the Superintendent of Documents, U.S. Government Printing OfBce Washington, D.C. 20402 - Price 65 cents (paper cover) CONTENTS Page Page Abstract. _ _ _ _ __ __________________________________ Bl Systematic descriptions._______ BIO Introduction _______________________________________ 1 Order Archaeogastropoda__ 10 Acknowledgments ___________________________________ 2 Family Trochidae_--__ 10 General remarks on Cretaceous gastropods of the western Order Mesogastropoda_ 11 interior._________________________________________ 2 Family Aporrhaidae___ 11 Pierre Shale gastropods______________________________ 3 Family Vanikoridae___ 22 Family Trichotropidae. 23 Red Bird section_ ________ _______________________ 3 Family Naticidae_____ 24 Diversity,_________________________________ 3 Family Cymatiidae___. 28 Abundance and occurrence___________________ 3 Order Neogastropoda______ 29 Preservation. ______________________________ 3 Family Fasciolariidae_. 29 Notes on ecology.__________________________ 3 Order Cephalaspidea ______ 33 Other areas ____________________________________ 5 Family Acteonidae____ 33 Colorado._________________________________ 5 Family Ringiculidae__. 34 South Dakota and Montana.________________ 7 Family Scaphandridae. 35 Bearpaw Shale of Montana and Canada_______ 8 Family Bullidae______ 35 Summary _ _____________________________________ 8 Order Bassomatophora____ 36 Proposed new species ________________________________ 9 Family Siphonariidae_. 36 Changes in generic or specific assignment ______________ 9 References ___________________ 40 Measurements of specimens __________________________ 9 Index.______________________ 43 ILLUSTRATIONS [Plates follow index] PLATE 1. Atiral, Euspira, Euspiraf, and Lunatia. 2. Aporrhais. 3. Drepanochilus. 4. Astandes and Drepanochilus. 5. Vanikoropsis and Vanikoro. 6. Vanikoropsis, Fasciolaria, Trachytriton, and Serrifusus. 7. Bullopsis, Ellipsoschapha, Cryptorhytis, Anomalofusust', and Graphidula. 8. Nonacteonina, Oligoptycha, and Anisomyon. 9-11. Anisomyon. Page FIGURE 1. Chart showing geographic and stratigraphic distribution of the gastropod species of the Pierre Shale of the Red Bird section_ _______________..-.---------------------- B6 2. Graph showing comparison of the suture to upper whorl carination and the intercarina- tion distances in the Pierre Shale species of Drepanochilus--.-,-------.------------- 13 3-7. Diagrams showing relation between whorl number and height and between whorl number and width: 3. Drepanochilus evansi Cossmaim------------------------------------------ 14 4. Drepanochilus pusillus (Stanton)____________-________--_----_------------ 15 5. Drepanochilus scotti Sohl, n. sp__________-___________------------.-------- 16 6. Drepanochilus nebrascensis (Evans and Shumard)._ _____________-_-------_ 18 7. Aporrhais biangulata Meek and Hayden_________________--_---_---_----- 21 8. Comparative plot between Euspira obliquata (Hall and Meek) (dots) and Natica sub- crassa Meek and Hayden (crosses) of pleural angle versus height of shell____ __________ 26 9. Graph showing comparison of height-width variation between Euspira rectilabrum (Conrad) and Euspira obliquata (Hall and Meek)________________---_--_---------- 26 10. Drawing of muscle-scar pattern of some species of Anisomyon Meek and Hayden ________ 37 11. Diagram of sculpture pattern of Anisomyon centrale.--------------------------- 38 IV CONTENTS TABLES Page TABLE 1. Distribution of the gastropod species in the members of the Pierre Shale of the Red Bird section. ____________________________________________________________________ B4 2. Distribution and abundance of aporrhaid genera in the Cretaceous rocks of North America_________________________________________________________________ 12 STRATIGRAPHY, PALEONTOLOGY, AND SEDIMENTATION OF A CLASSIC REFERENCE LOCALITY OF THE PIERRE SHALE UPPER CRETACEOUS GASTROPODS FROM THE PIERRE SHALE AT RED BIRD, WYOMING By NORMAN F. SOHL ABSTRACT formally. These two species represent part of an evolving line­ The Pierre Shale gastropod faunas show a great similarity age characterized by a change from older to younger species in at almost all stratigrapliic levels over the whole of the western 1. The upper whorl carination becoming proportionally closer interior, from Colorado and Wyoming eastward to the Dakotas to the suture, and eastern Montana. The equivalent Bearpaw Shale of Canada 2. Proportional narrowing of the intercarination area, and Montana contains the same fauna. Aside from taxonomic 3. Progressive development of nodes on the upper body whorl uniformity, one consistent feature of the fauna is that the upper carination, and stratigraphic levels contain a greater abundance and diversity 4. Loss on inner surface of expanded outer lip wing of a welt of gastropods than the lower stratigraphic levels. Compared that parallels wing edge. to the overlying Fox Hills Sandstone there is a significant Of special note is the discovery of specimens retaining the change, very few species being common to the .two forma­ muscle-scar pattern in species of the unusual siphonariid tions, and many genera that are common in one formation are pulmonate gastropod Anisomyon. Although all retain the basic absent in the other. muscle-scar pattern with an interruption of the band in the right posterior quadrant, the amount of variation in positioning Contrary to published consensus the Pierre .Shale gastropod fauna 'Shows considerable similarity to the contemporaneous of other parts of the 'band is high. Many of the species are figured for the first time since Meek's faunas of the gulf coast. This similarity increases to the south classic studies (1876) ; therefore the opportunity has 'been taken in Colorado, especially in the sandier units, such as the I/arimer Sandstone Member of the Pierre Shale of the Front Range of to illustrate photographically most of the type specimens. Colorado. As an example, of the 53 gastropod genera repre­ INTRODUCTION sented in the Pierre Shale only 8 are not common to the gulf coast. Some genera, such as Bullopsis, Oliffoptycha, Belliscala, The primary purpose of this paper is to redefine, Lomirosa, Remera, Scobinodolus, and Napultts, are known only describe, and figure the gastropod species occurring in from these two areas. In spite of these similarities, genera a complete section of the Pierre Shale in the vicinity of such as Turriteila, and Pugnellus, $<o common in the Coastal Plain Cretaceous sediments, are absent in the Pierre Shale, Eed Bird, Niobrara County, Wyo. (sees. 13, 14, 23, T. although in some nearshore sandier facies, such as the Lewis 38 N., R. 62 W.). This work is a part of a larger in­ Shale, they may be abundant. vestigation of the fauna and microflora recovered from The gastropod fauna is consistent with a marine shallow- the more than 3,000 feet of Pierre Shale at this locality. water environment and includes both epifaunal and infaunal The detailed stratigraphy and associated problems have elements. Feeding habits range from plant browsers to detritus feeders and carnivores. The absence of filter feeding snails may been outlined by Gill and Cobban (1966). The strati- be a reflection of particle size of the sediment or excessive graphic nomenclature and faunal zonation used in this turbidity. paper are defined by the aforementioned authors. Gastropods occur through 1,700 feet of the 3,137-foot sequence To adequately discuss and define the gastropod species of Pierre Shale in the Red Bird section. They first appear in of the Red Bird section it has been necessary to include the uppermost bed of the Mitten Black Shale Member and range upward to the lower part of the Baculites grandis zone beds. figures of the type material, most of which has not been They are most abundant and diverse in the upper part of the figured since the time of Meek (1876). Collections section, especially in beds of the Baculitcs baculus zone. from other areas of outcrop in the Fox Hills Sandstone In the Red Bird section, 23 distinct gastropod species occur. and Pierre Shale have been studied, and some specimens Several others are assignable only to genera because of poor from these formations have been included herein. The preservation. Two-thirds of the gastropods belong to the sub­ class Streptoneura and one-third to the Euthyneura. Although most valuable of these consist of the gastropod portions four 'species are cited as new, only two, DrepanocMlus scotti of more than 1,000 collections, made by W. A. Cdbban and D. obesus, are represented by sufficient material to name and associates, from the Pierre Shale of the Front Bl B2 DESCRIPTIVE STUDY OF A CLASSIC REFERENCE LOCALITY OF THE PIER RE SHALE Range in Colorado. All collections are precisely lo­ the Tonnacea rather than the Fasciolariidae of the Buc- cated stratigraphically and have formed the major basis cinacea. The change in assignment is not only at the