GIANT GROUND SLOTHS — GAZIN 



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Since the fifth digit, which is invariably next to the ground, lacks a 

 claw in both genera, Eremotherium has but two claws on the front 

 foot, a distinction rather paralleling that between the living two- 

 and three-toed tree sloths of Central America. 



Figure 4. — Right hindfoot (U.S.N.M. No. 20872, partially composite among smaller tarsals, 

 and phalanges of fourth and fifth digits restored) of Eremothfrium rusconii (Schaub) 

 from El Hatillo. Proximal or inner margin of foot which turns upward in walking. About 

 1/9 natural size. 



Figure 5. — Right hindfoot (same as fig. 4) of Eremotherium rusconii Schaub from El Hatillo. 

 Outer view of foot (approximately the dorsal surface of the normal mammalian foot). 

 Note that the hindfoot had only three toes remaining, the third to the fifth digits, and 

 only the upper or third had a claw. About 1/9 natural size. 



In contrast to the reduction in toes from the normal mammalian 

 number, a specialization regarded as advanced in character, the 

 Eremotherium forefoot is primitive in another respect. In certain in- 

 stances it was noted that the centrale, a small bone near the center of 

 the wrist, was distinct and not fused with one of the adjacent carpal 

 elements. In Megatherium this element has apparently not been ob- 

 served separate; evidently it early fused with the adjacent unciform. 

 Separation of this element, however, is not invariable in Ere- 

 motherium. 



The hindfoot of Eremotherium (figs. 4 and 5) is less distinctive in 

 comparison with Megatherium (fig. 6). As in this genus it had but 



