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A FURTHER STUDY OF THE LOWER EOCENE 



MAMMALIAN FAUNAS OF SOUTHWESTERN 



WYOMING^ 



By C lewis GAZIN 



Curator, Division of Vertebrate Paleontology 



United States National Museum 



Smithsonian Institution 



(With 14 Plates) 

 INTRODUCTION 



Continued exploration for the Smithsonian Institution of the 

 early Tertiary deposits of the Wyoming region has included further 

 investigation of the lower Eocene sequence in the southwestern part of 

 the State. Collections described by the author in 1952 were derived 

 principally from the Knight beds along the Green River in the vi- 

 cinity of La Barge and Big Piney in Sublette County, although scant 

 remains from other localities and horizons were discussed. Particu- 

 lar attention to the less well represented occurrences has since resulted 

 in considerably larger collections furnishing us with much better in- 

 formation on various faunas and their age relationships. 



The later work in this area by the author's field party was di- 

 rected in a large measure toward increasing the faunal representation 

 from the New Fork beds above the Tipton tongue in the northerly 

 part of the Green River Basin. Repeated search with the develop- 

 ment of quarries in the lowest levels of the Knight near Bitter Creek 

 Station in the Washakie Basin proved fruitful in adding significantly 

 to the collections made here by Cope in 1872 and by Marsh in 1876 

 and 1882. Work in the Washakie Basin has also included systematic 

 search of the Cathedral Bluffs beds and of the higher levels of the 

 Knight below the Tipton tongue of the Green River formation in 

 selected areas, particularly in the eastern portion. Moreover, detailed 

 examination was made of widely scattered exposures of the Knight in 



1 Study of early Tertiary mammals is currently aided by a grant from the 

 National Science Foundation. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 144, NO. 1 



