20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



be little or no actual difference in foot structure among these — a 

 versatility attributed to the characteristics of the foot pads. 



I see no difficulty in attributing a ground habit in a savannalike 

 environment to M eniscotherium, as suggested for the two larger 

 species ; nevertheless, the foot structure seems rather primitive so that 

 a variety of conditions might be included. The readily divergent, 

 although somewhat reduced, pollex and hallux ; the flexibility of the 

 foot articulations with tendency toward supination of the feet, par- 

 ticularly noted for the manus ; and the indication of strong abductors 

 and adductors suggest that adaptability may have extended to 

 climbing. As a herbivore the comparatively weaker foot structure 

 implied in the near serial arrangement, in comparison with contem- 

 porary perissodactyls, suggests less potential toward a cursorial habit, 

 Kowalevsky's inadaptive type, possibly contributing to extinction. 



Fig. 1. — Meniscotherium chamense Cope. Drawing based on composite skeleton 

 in the American Museum of Natural History. Largo beds of San Jose for- 

 mation, San Juan Basin, N. Mex. 



Cope (1884b) pointed out that Meniscotherium had a relatively 

 larger brain than Phenacodus and that the oblique articular surfaces 

 of the cervical vertebrae indicated the elevation at which the head 

 was held. In his "restoration" of Meniscotherium he concluded that 

 the body had the robust proportions of a raccoon, with the fore and 

 hind legs rather short and of equal length (see fig. 1 ). 



CLASSIFICATION 



Condylarthra Cope, 1881 

 Meniscotheriidae Cope, 1882 

 Meniscotherium Cope, 1874 



Synonym. — Hyracops Marsh, 1892 



Type species. — Meniscotherium chamense Cope 



