PALEOCENE MAMMALS OF CENTRAL UTAH GAZIN 



29 



Additional lower jaw material of E. shepherdi collected in 1939 

 includes two specimens, No. 16289 and No. 16303, in which P4 is 

 preserved in association with the molars, rendering more certain 

 the reference of several isolated lower premolars to this species. P4 

 is seen to be comparable in size to that in E. lemuroides but showing 

 a distinct metaconid, a slight paraconid, and two cusps at the 

 posterior margin of the talonid. These are variably developed in 

 the premolars referred to E. shepherdi, but more distinct that in E. 

 lemuroides and other species from the San Juan Basin. The meta- 

 conid is better developed than in specimens of the smaller E. aquilo- 

 nnis but not to the extent seen in Litaletes disjunctus, nor is the 



Figure 16. — Ellipsodon shepherdi Gazin: a. Portion of right ramus of mandible with 

 M2-M3 (U.S.N.M. No. 15721), type specimen, lateral and occlusal views; b, right maxillary 

 portion with P^M^ (U.S.N.M. No. 15790), lateral and occlusal views. X 3. Dragon 

 Paleocene, Utah. 



paraconid of P4 so well defined as in Litaletes. The moderately 

 enlarged P4 and the brachydont condition of the teeth, combined with 

 the reduced size of M3, indicate a closer relationship to certain of 

 the species regarded as Ellipsodon than to Litaletes disjunctus. 



The upper teeth, P* to M^ in the maxilla, No. 15790 (fig. 16, 5), 

 referred to Ellipsodon shepherdi are relatively smaller than in the 

 type lower jaw and approach somewhat closer to E. acolytus than 

 to E. lemuroides in size; however, this difference within the Dragon 

 material may not be greater than can be accounted for b}' individual 

 variation. 



P* shows a cusp in the position that would be occupied by the 

 metaconule in the molars. This is absent in the somewhat smaller 

 P* of the Puerco form, E. priscus, but was observed in certain 

 specimens of the later material. P* is noticeably larger than in E. 

 aequidens, and M^ and M^ are relatively longer. 



