PALEOCENE MAMMALS OF CENTRAL UTAH GAZIN 



43 



Genus PERIPTYCHUS Cope 



PERIPTYCHUS GILMOREI =3 Gazin 



Periptychus gilmorei Gazin, 1938, p. 275. 



The large periptychid, P. gilmoi^ei^ in the Dragon fauna is rather 

 well represented in the collection, the best specimen being the type, 

 No. 15537, and including portions of right and left maxillae with 14 

 teeth in all (fig. 23). Specimen No. 16228, obtained in 1939, includes 

 portions of both maxillae with P*-M^ and a portion of the left 

 ramus of the mandible with P4-M3, the lower teeth being partially 

 embedded in barite. The lower dentition is best represented in speci- 

 men No. 15689 (fig. 24), which includes portions of right and left 

 rami, exhibiting M2-M3 and P4-M2, respectively. 



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Figure 23. — Periptychus giimorei Gazin : Right upper dentition including P--M* (U.S.N.M, 

 No. 15537), type specimen, lateral and occlusal views, X 1}£ Dragon Paleocene, Utah. 



Periptychus gihnorei is intermediate between C arsioptycJius coarc- 

 tatus from the Puerco and Periptychus carinidens from the Torrejon 

 in almost all characters of the upper dentition. The teeth are 

 relatively wide transversely as compared with their length, and the 

 premolars are only slightly larger than the molars. The premolars 

 show the inner crescent developed almost as much as in Periptychus 

 carinidens^ but the deuterocone portion is more constricted antero- 

 posteriorly, although not so much as in Garsioptychus coarctatus. 

 Moreover, P^ is much more like that in Periptychus than the simple 

 condition observed in several specimens of Garsioptychus. 



The molar teeth show a distinct resemblance to those in Garsiop- 

 tychus^ and in addition to their being relatively wide transversely 

 they show a more distinct external cingulum than in Periptychus. 



« Named for C. W. Gilniore, whose party discovered the first Dragon Canyon locality. 



