CYCLOPIDIUS 251 



Cyclopidius brevifacies (Cope) 1878 = ? C. simus Cope 



Figs. 178-179 



Original Reference: Descriptions of new Vertebrata from the Upper Tertiary formations of the West. 

 Proc. Amer. Philos. Soc, XVII, p. 219, pi. 27, figs. 2-3 (Pithecistes brevifacies). 



Type Locality: Smith River Valley, Montana. 



Geologic Horizon: Upper Miocene (Deep River). 



Type: Holotype, Cat. No. 8129 A.M.N.H., right ramus and extreme anterior part of left, coossified at 

 symphysis. Teeth much worn, Mj and incisors lacking. 



Specific Characters: Complete skull unknown. According to Cope, the species, "was about 

 the size of a red fox." 



Mandible: The symphysis was coossified and short but very robust. Its upper surface on each 

 side bears a low longitudinal swelling. The chin is quite straight, the symphysiodental angle being 

 around 63°. Vertically there is slight concavity in the front. The horizontal ramus is deep, espe- 

 cially posteriorly. 



Fie. 178. — CyclopiJius brevijacies (Cope). Frag- Fig. 179. — Cyclopidius brevifacies (Cope) . Supe- 



mentary mandible. HT. Cat. No. 8129 A.M.N.H. rior view of mandible. HT. Cat. No. 8129 



Nat. size. (Redrawn from Cope, 1888.) A.M.N.H. Nat. size. (Redrawn from Cope, 1888.) 



Dentition: The incisors are lacking, but the alveoli of two on each side show them to have been 

 quite small. The canine is small, more or less cylindrical in section, and separated from Pi by a 

 very small diastema. Pi is quite small but larger than P 2 . The transverse diameter at the base of 

 the crown of the latter exceeds the anteroposterior. The crown of P 3 is wider than long, and that of 

 P 4 is longer than wide. The molars increase rapidly in anteroposterior length from 1 to 3. The 

 length of M s equals the total premolar length. The metastylid of M 3 is unusually long and well 

 developed. The tooth row as a whole seems to have a slight curvature, the maximum outward bow 

 being about at the line between the molars and premolars. 



Discussion: The name Pithecistes was given by Cope to this material, because "the form of the 

 mandible of this animal, as well as the number and proportions of the teeth, curiously resemble that 

 of the corresponding part of a monkey." 



Cope (1878A, p. 219) misinterpreted the dental formula, so that, as stated by him, it is Ii, Ci, 

 P 3 , M 3 , whereas these same teeth are Ci, Pi, P4, M 3 . In addition he wrote: "The single incisor of 

 each side is weak and easily lost, and there is on one side only, a small alveolus for a minute second 

 incisor. It is therefore probable that in some individuals the incisive formula is 2." This specimen 

 may perhaps be later than the other species and may have had but two incisors on each side, instead 

 of the more normal three in the lower jaw. In any event, they must have been tiny, and we have 

 no way at present of determining the number and size of the incisors. Cope's incisor is the true 

 canine, while his canine is P x . He considered that the canine (Pi) "closes in front of the superior 

 canine in the usual manner." This is not the usual manner in this group, for in every oreodont the 

 lower functional caniniform tooth (Pi) closes behind the upper (true) canine. 



