Fresh-Water Mollusks of Cretaceous Age From Montana and Wyoming GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-A Fresh-Water Mollusks of Cretaceous Age From Montana and Wyomin By TENG-CHIEN YEN SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1950, PAGES 1-20 GEOLOGICAL SURVEY PROFESSIONAL PAPER 233-A Part I: A fluviatile fauna from the Kootenai formation near Harlowton, Montana Part 2: An Upper Cretaceous fauna from the Leeds Creek • area, Lincoln County', Wyoming UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1951 UNITED STATES DEPARTMENT OF THE INTERIOR Oscar L. Chapman, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 45 cents (paper cover) CONTENTS Page Part 1. A fluviatile fauna from the Kootenai formation near Harlowton, Montana. _ 1 Abstract- ______________________________________________________________ 1 Introduction ___________________________________________________________ 1 Composition of the fauna, and its origin.._________________________________ 1 Stratigraphic position and correlations_______________________________---___ 2 Systematic descriptions.__________________________________________________ 4 Bibliography. __________________________________________________________ 9 Part 2. An Upper Cretaceous fauna from the Leeds Creek area, Lincoln County, Wyoming_________________________________________________________ 11 Abstract.__________________-_________________________-____:__-_-_---___ 11 Introduction ___________________________________________________________ 11 Review of previous records___.._______-___-__-____________-_--______---___ 11 Composition of the faunas.______________________________________________ 11 Stratigraphic positions_________________________________________________ 13 Systematic descriptions of the molluscan species.______ _ _________________ 14 Bibliography._ _________________________________________________________ 17 Index..._________________________________________________________________ 19 ILLUSTRATIONS Plate 1. Fossil and recent fresh-water mollusks._______________________ Following index 2. Upper Cretaceous nonmarine mollusks_-___-_--_____________ Following index ni FRESH-WATER MOLLUSKS OF CRETACEOUS AGE FROM MONTANA AND WYOMING l By TENG-CHIEN YEN PART 1. A FLUVIATILE FAUNA FROM THE KOOTENAI FORMATION NEAR HARLOWTON, MONTANA ABSTRACT Shawmut anticline, on the west side of a trail leading The paper presents a fresh-water molluscan assemblage found to the abandoned ranch. in the Kootenai formation southeast of Harlowton, Montana, After publication of Dr. Stanton's report, several which indicates that the enclosing bed is of fluviatile origin. Molluscan faunas from contemporary beds, such as the Cloverly additional collections were made at this locality. They, formation of central Wyoming and the Peterson limestone in the plus certain species from the Cloverly formation and Gannett group of western Wyoming, are compared with it. An the Peterson limestone of Wyoming, are the basis of the account of 29 species of pelecypods and gastropods is given, of present paper. which 4 genera and 8 species of gastropods are herein described as new. COMPOSITION OF THE FAUNA, AND ITS ORIGIN INTRODUCTION The fossiliferous bed, which consists of coarse-grained, It is nearly half a century since the invertebrate shaly sandstone and nodular limestone of rusty color, fauna of the Kootenai formation near Harlowton, yielded the following species of mollusks in addition to Montana, was first described by T. W. Stanton. Dr. some ostracodes and teeth of fish and reptiles: Stanton's paper (1903) was based on a collection made Pelecypoda by members of the Geology Department of Princeton Family Unionidae University, and in it he described the following species Protelliptio douglassi Stanton Unio farri Stanton of fresh-water mollusks: U. natosini McLearn Unio ja/rri Stanton Family Sphaeridae Unio douglassi Stanton Eupera onestae (McLearn)' Campeloma harlowtonensis Stanton Gastropoda Family Neritidae Viviparus montanensis Stanton Mesoneritina nebrascensis (Meek and Hayden) Goniobasis? ortmani Stanton Family Amnicolidae Goniobasis? silberlingi Stanton Reesidella montanaensis (Stanton), n. gen. On the evidence of these few species, Dr. Stanton con­ Stantonogyra silberlingi (Stanton) Mesochilina cretacea, n. gen and sp. cluded at this initial stage of geological exploration of Family Viviparidae the area, that the fossil-bearing bed is "certainly not Campeloma harlowtonensis Stanton older than Lower Cretaceous." The conclusion was Family Pleuroceratidae significant as the recognition of a new assemblage, still Circamelania ortmanni (Stanton), n. gen. acceptable as the standard Lower Cretaceous fresh Family Physidae Physa montanensis, n. sp. water molluscan fauna in North America. P. sp. undet. A The fossiliferous bed is exposed in the SW% sec. 27, Family Planorbidae T. 7N.,K. 16E., about 12 miles southeast of Harlow­ Gyraulus cf. G. veternus (Meek and Hayden) ton, about 6 miles southwest of Winnicook, and about Carinulorbis sp. undet. \% miles northwest of the old Widdecomb Kanch. The The molluscan fauna is rich in variety as well as in bed is well exposed over a few hundred square feet at individuals. The prosobranchian gastropods include the top of a low foothill of the West Dome of the six species represented by many specimens, but the pulmonates yield only four species, each represented by i A contribution from a research project (NR-081-097) supported by the Geophysics only a few individuals. Branch, Office of Naval Research, Department of Navy. It is carried on under ONE Contract N9-onr-92601 with the Smithsonian Institution, Washington, D. C., The fauna seems to indicate that the enclosing bed and is published by permission of the Secretary of the Smithsonian Institution. was of fluviatile origin and that molluscan species 1 FRESH-WATER MOLLUSKS FROM MONTANA AND WYOMING from the upper course of a river were drifted by floods Amnicolidae and gathered in a "pocket," where they were preserved. Amnicola longinqua Gould (abundant) A strikingly similar Recent molluscan assemblage was Fluminicola fusca (Haldeman) (common) collected from silt at a high-flood level at the Great Physidae Falls of the Potomac River, near Washington, D. C. Physa ampullacea Gould (rare) The similarity is emphasized when the faunas are listed Physa sp. undet. (common) in parallel columns: Lymnaeidae Lymnaea utahensis Call (abundant) Kootenai bed near Harlowton Great Falls of the Potomac Lymnaea palustris buttoni Baker (common) River 2 Protelliptio douglassi (com­ Planorbidae mon) Gyraulus vermicularis (Gould) (rare) Unio farri (rare) Elliptic complanatus (com­ Helisoma subcrenatum (Cooper) (rare) Unio natosini (rare) mon) Carinifex newberryi (Lea) (abundant) Eupera onestae (common) Sphaerium stamineum (abundant) The similarity in composition of the Kootenai fauna Mesoneritina nebrascensis to that of the deposit near the Great Falls of the (rare) Potomac River, in addition to suggesting a fluviatile Reesidella montanaensis Amnicola limosa (com­ (abundant) mon) origin for the Kootenai formation, may possibly also Stantonogyra silberlingi Amnicola decisa (rare) imply a general similarity of the water body, in which (rare) Gillia altilis (common) the Kootenai formation was deposited, in movements, Mesochilina cretacea (rare) depth, and volume of the water, permanency and size Campeloma harlowtonensis Campeloma decisum (rare) of the river, and constituents of soil and climate of the (rare) Lioplax subcarinatus (com­ mon) area. However, the abundance of rissoid snails, Circamelania ortmanni Goniobasis virginica (abun­ together with planorbid species, in the Kootenai forma­ (abundant) dant) tion may indicate that a more luxuriant aquatic vege­ Anculosa carinata (com­ tation along the extinct river favored such gastropods. mon) The faunal lists indicate only relative abundance and Physa montanensis (rare) Physa sp. undet. A (rare) Physa heterostropha (rare) the species listed are not to be taken as completely Gyraulus cf. G. veternus representative of the existing fauna. Likewise, it is (rare) known that, although planorbid species have been found Carinulorbis sp. undet. ___________________________ in some parts of the Potomac River they are not repre­ (rare) sented in the collection made at the Great Falls. This However remote it may be, the possibility that the incompleteness suggests that the assemblage has come Kootenai formation is lacustrine should be considered. together from parts of the river where planorbids are A few molluscan species similar to those in the assem­ rare or wanting and the other species are abundant. blage found at the Great Falls are also obtainable in lakes, especially in large ones connected with streams. STRATIGRAPHIC POSITION AND CORRELATIONS In such lakes the assemblage of species is generally It is generally accepted now that the Kootenai forma­ different, however, for there are generally more species tion in Montana is of Early Cretaceous age. On the of pulmonates and more shallow-water forms, and the evidence of the molluscan species, part of these beds fluviatile species, if any, may be represented by few may be correlated with the Cleverly formation in individuals. A convincing example is an assemblage Wyoming and part with the Peterson limestone of the drifted to the shore of Bear Lake, Idaho and Utah, Gannett group in Wyoming and Idaho. The precise which includes the following molluscan species: