452 LAND MAMMALS IN THE WESTERN HEMISPHERE 



which was not ancestral to them, but collaterally related and 

 descended from a common ancestry. The largest and most 

 dominating of Wasatch mammals was the genus ^Coryphodon, 

 which also occurred in the lower Eocene of Europe, and the 

 species of which ranged in stature from a tapir to an ox, though 

 of much heavier form than the latter. The latest surviving 

 species lived in the Wind River stage as a contemporary 

 of \Bathyopsis, but then the suborder gave way to the 

 fuintatheres. 



In 'fCoryphodon (see Fig. 142, p. 279) the number of teeth was 

 unreduced, a fact which is recorded in the name of the suborder, 

 the dental formula typical of all the primitive ungulates being 

 applicable to the genus. This formula was : if, c\,p |, wf, 

 X 2 = 44. The upper incisors were rather small, but functional, 

 and the canines of both jaws were formidable tusks, though not 

 rivalling in size the great sabres of the fuintatheres ; the pre- 

 molars had a simpler structure than the molars, which resembled 

 those of the fuintatheres in a general way, but not closely. The 

 skull differed greatly from that of the fuintatheres in having 

 no horn-like protuberances, and was relatively large and heavy, 

 the cranium having a broad, flat roof and no sagittal crest, and 

 the lower jaw had no descending flange from the inferior border ; 

 in every way this skull was more normal and less bizarre- 

 looking. The neck was proportionately longer than in the 

 fuintatheres, the body long and the tail of medium length ; 

 the trunk-vertebrse had .surprisingly small and weak spines, 

 perhaps an indication of aquatic habits. The limbs were 

 quite short and very heavy, and the bones, in comparison with 

 those of the fuintatheres, were less proboscidean and more 

 perissodactyl in character. For example, the femur retained 

 the third trochanter and the long bones had marrow-cavities. 

 The feet, on the contrary, were very like those of the fuin- 

 tatheres, being extremely short and five-toed and with reduced, 

 nodular hoof-bones ; even in the details of the wrist and ankle 

 joints there was no important difference between the two groups. 



