NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 55 



PROTOREODON PARADOXICUS 26 (Scott), 1898 



Type. — Skull, jaws, a few vertebrae, limb and foot bones, P.U. 

 No. 1 1234. 



Horizon and locality. — Upper Uinta B or lower Uinta C, mouth of 

 White River, Utah, according to Thorpe. 



Discussion. — The dentition in the type of Protoreodon \paradoxicus 

 is only a little smaller than that of Protoreodon parvus. It exhibits, 

 however, distinctly more primitive appearing premolars. P^, for 

 example, is three rooted but shows scarcely more than a robust cingu- 

 lum at the position of the deuterocone, and in P* the deuterocone is 

 decidedly conical in comparison with that in P. \parvus. Moreover the 

 primary cusp in P* of P. paradoxicus, though somewhat worn, is 

 almost certainly not twinned. The molars show noticeable wear but 

 are perhaps more conical than in P. parvus; also, the parastyles are 

 rather more outstanding. The canines in the type specimen are par- 

 ticularly large so that I suspect this is a male individual. I^ is present 

 on one side, but beyond this the premaxillae are not sufficiently 

 complete to warrant further conclusions regarding the number of 

 incisors. 



Beyond doubt Protoreodon paradoxicus possesses the most primi- 



MEASUREMENTS IN MILLIMETERS OF DENTITION IN TYPE SPECIMEN OF 



Protoreodon paradoxicus, p.u. no. 11234 



Length of upper cheek tooth series, C (at alveolus) -M^ inclusive 59.6 



Upper premolar series, P^-P*, inclusive 19.5 



Upper molar series, M^-M^ inclusive 23.4 



C, anteroposterior diameter 7.0 



P', anteroposterior diameter : transverse diameter* 6.70 : 3.50 



P^ anteroposterior diameter : transverse diameter 6.7 : 5.6 



P*, anteroposterior diameter : transverse diameter 6.4 : 8.7 



M\ anteroposterior diameter : transverse diameter* 7-3 : 8.8 



M', anteroposterior diameter : transverse diameter 8.2 : 8.7 



M^ anteroposterior diameter : transverse diameter 8.8 : 12.1 



Lower molar series, M1-M3, inclusive 27.1 



P3, anteroposterior diameter 7-5 



Pi, anteroposterior diameter : greatest transverse diameter 8.0 : 4.4 



Ml, anteroposterior diameter : transverse diameter of talonid 7-i : 5-5 



M2, anteroposterior diameter : transverse diameter of talonid 8.0: 6.0a 



Ma, anteroposterior diameter : transverse diameter of trigonid 12.5 : 6.3 



a. Approximate. 

 _ * Measurements of posterior upper premolars are taken anteroposteriorly across outer por- 

 tion and transversely perpendicular to outer margin. Those of upper molars are ta!ken 

 anteroposteriorly perpendicular to anterior margin and transversely across anterior portion 

 of tooth. 



26 Illustrated in Scott, 1899, pi. 4, figs. 24-25; and Thorpe, 1937, fig. 11; pi. i, 

 fig. 2. 



