NO. 2 A STUDY OF MENISCOTHERIUM — GAZIN 19 



The hyrax Procavia is reported (Coe, 1962) to be selective in its 

 feeding habits with a preference for grasses, mosses, and certain 

 higher plants with succulent leaves. There is no paleobotanical 

 evidence for grasses during the early Eocene, but the grasslike sedges 

 and certain of the possibly harsher elements of the flora may have 

 been more suitable for Meniscotherium than for Phenacodus or 

 Hyracotherium. No doubt mosses and a variety of succulent leaves 

 were available for selection. Phenacodus, on the other hand, quite 

 possibly had a more omnivorous habit. 



The feet of Meniscotherium are moderately robust but show the 

 structural weakness of a serially arranged condylarthran tarsus, some- 

 what less evident in the carpus. The feet are pentadactyl, but with 

 the lateral digits in the pes, particularly the hallux, reduced. The 

 ungual phalanges are elongate and distally flattened dorsoventrally 

 or spatulate, much more so than in Tetraclaenodon but not so 

 broadly as in Phenacodus. The structure of the foot is rather similar 

 to that of the hyrax in the serial arrangement of the tarsus, some- 

 what less so in the carpus, and the feet have about the same relative 

 size although they are a little more robust. They differ most notice- 

 ably in the articular arrangement between the tarsus and the tibia 

 and fibula and in less reduction of the lateral digits and ungual pha- 

 langes. The lateral digits of the pes are lost in the hyrax, and the 

 pollex (only) is vestigial in the manus. The distal phalanges, more- 

 over, while broadly articulating with the second phalanges, are 

 scarcely more than nubbins of bone in the hyrax. 



Although the hyrax has a plantigrade foot with pads developed 

 from the nails to the carpus and tarsus, I suspect that Meniscotherium 

 was digitigrade or at least semidigitigrade, to judge by the rather 

 different appearance of the inferior margin of the calcaneum. That 

 in the hyrax is more distinctly flattened. The elongate distal phalanx 

 in Meniscotherium, with the dorsoventrally somewhat flattened nail- 

 like hoof interpreted, and the character of the articulation between 

 the various phalanges suggest that all these, at least of the three 

 median digits, rested on the ground. From these considerations it 

 would appear that the weight was borne essentially on the ends of 

 the metapodials, quite unlike the hyrax. Any possible interpretation 

 of habit by analogy of foot structure is further complicated by the 

 fact that remarkably different habits are shown by different groups 

 of procaviids. While Procavia and Heterohyrax are ground- and 

 rock-dwelling forms, Dendrohyrax lives in trees. There seems to 



