610 



CONDYLARTHKA. 



plantigrade, but Phenacodus was digitigrade. The carpus and 

 tarsus (Fig. 321) are very similar to those of Procavia (Fig. 

 290) ; the bones of the two rows are usually serially arranged 

 and the navicular articulates laterally with the cuboid. The 

 astragalus has a neck and convex distal surface, and resem- 

 bles that of 



A "R 



theCreodonta. 

 The three mid- 

 dle digits are 

 longer than the 

 outer, and the 

 axis of the limb 

 traverses digit 

 No. 3 as in Pe- 

 rissodactyla. 

 The terminal 

 phalanges are 

 expanded and 

 pointed and 

 musthave car- 

 ried hoof-like 

 nails. The 

 femur has a 

 third trochan- 

 ter another 

 v perissodactyl 

 feature. Ulna 

 and fibula are 

 separate and 

 complete, and 



KG. 321Hyracops socialis Marsh. Lower Eocene, Wasatch. the fibula ends 



A left manus, B left peg (after Marsh, from Woodward). R f r ppl v oo j^ 



radius, [7 ulna, s scaphoid, I lunar, p pisiform, ce centrale, tm trape- * "*J 



zium, td trapezoid, m magnum, u unciform, ca calcaneum, a astra* (* Q rr , i A T /-> r a 

 galus, n navicular, cb cuboid, 1, 2, 3 cuneiforms, x epicuneiform. 



The tail ap- 

 pears to have been of some length. They were probably 

 omnivorous animals and they varied from the size of a tapir 

 to that of a fox. 



This appears to be a central group with affinities to the 

 Creodonta, Perissodactyla, and to the Hyracoidea. Affinities 

 to the Insectivora and Primates have also been claimed by 



