184 



THE MERYCOIDODONTID/E 



general shape of the jaw is like that of Merycoidodon, but the jaw is shorter and somewhat more 

 spout-shaped anteriorly. The angle descends slightly below the level of the horizontal ramus and 

 is regularly convex. The posterior border of the ascending ramus is nearly straight in its median 

 part. The condyle is not particularly wide transversely and is set well in from the posterior border 



Fig. 134. — P henacoccelus typis Peterson. Inferior view of skull. Teeth in outline because so badly worn the pattern does 

 not show. PT. Cat. No. 1276 CM. 1/2 nat. size. (Drawn from Peterson, 1928.) 



of the ramus. The sigmoid notch is shallow and open. The coronoid process rises steeply and 

 terminates in a rounded point, directed slightly posteriorly. The masseteric fossa is deep and rather 

 large but hardly extends below the line of the alveolar parapet. 



Foramina: The infraorbitals lie above P 3 . The supraorbitals are about a third nearer the 

 sagittal suture than the supraorbital border, on a line through the posterior quarter of the orbits. 







Fie. 13 5. — P henacoccelus ty pus Peterson. Superior 

 dentition. PT. Cat. No. 1335 CM. 2/3 nat. 

 size. (Drawn from Peterson, 1928.) 



Fig. 136. — Phenacoccelus ty pus Peterson. Inferior 

 dentition. PT. Cat. No. 1335 CM. 2/3 nat. 

 size. (Drawn from Peterson, 1928.) 



The foramen ovale is large and in normal position. The condylar foramen is also large and located 

 close to the anterior margin of the condyle. The posterior palatine foramina are opposite the 

 anterior half of P 4 . 



Dentition: Full complement of 44 teeth ; molars brachyodont to subhypsodont. 



Superior: The incisor crowns are moderately short and the teeth set close together. A short 

 diastema separates C from P 1 , which is obliquely placed, as is P 2 . In Merycoides cursor these 

 premolars are nearly straight. P 3 seems to have the posterior and anterior crescents more nearly 

 equal in development, whereas in Merycoides the posterior is much the larger. In P 4 the outline of 

 the lingual side is more V-shaped, while that of Merycoides is U-shaped. The parastyles and 

 mesostyles are considerably thinner than in Merycoides, and the metastyle is less prominent. 



Inferior: These teeth are crowded the same as are the upper series. There is no diastema 

 between Pi and P 2 . P2 is set obliquely and is overlapped by P 3 , which in turn is partly overlapped 



