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EARLY TERTIARY APHELISCUS AND 



PHENACODAPTES AS PANTOLESTID 



INSECTIVORES 



By C. LEWIS GAZIN 



Curator, Division of Vertebrate Paleontology 



United States National Museum 



Smithsonian Institution 



(With Two Plates) 



INTRODUCTION 



Examination in 1954 of Phenacodaptes material in the Paleocene 

 collections at Princeton University, believed pertinent to a review of 

 Eocene artiodactyls then underway, led to rather inconclusive results. 

 Dr. Jepsen's tentative suggestion (1930, p. 519) of such a relationship 

 may, nevertheless, have merit. 1 More recent studies of the Knight 

 faunas, however, involved certain pantolestids, and comparison of 

 these among a wide range of both Eocene and Paleocene forms has 

 convinced me that Cope's Apheliscus and Jepsen's Phenacodaptes are 

 closely related and that both are pantolestids, although perhaps some- 

 what less closely related to the Pantolestinae than to the Pentaco- 

 dontinae. Their relationships would seem possibly best illustrated by 

 placing them both in the Apheliscinae as a subfamily of the Panto- 

 lestidae. 



I am indebted to Dr. Glenn L. Jepsen for permitting me to borrow 

 and illustrate specimens of Phenacodaptes sabulosus in the Princeton 

 collections, and to Dr. George G. Simpson and Mrs. Rachel H. Nichols 

 for sending me materials of Apheliscus insidiosus and Pentacodon 

 inversus from the collections of the American Museum. The pencil 

 drawings of specimens shown in the accompanying plates were made 

 by Lawrence B. Isham, scientific illustrator for the Department of 

 Geology in the U. S. National Museum. 



PREVIOUS INTERPRETATIONS OF RELATIONSHIP 



Apheliscus insidiosus was described by Cope (1874, p. 14) from 

 the lower Eocene San Jose beds in New Mexico. He described it 



1 After this manuscript was submitted for publication, Dr. Jepsen showed me 

 a note that he had placed in the collection drawer some time ago suggesting that 

 Phenacodaptes be compared more carefully with Apheliscus. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 139, NO. 7 



