356 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



hensile upper lip the branches upon which they browsed. 

 This explanation may perhaps be applicable to all of these 

 aberrant and exceptional groups of hoofed animals. 



In the lower Miocene (Arikaree stage) of North America 

 well-nigh complete skeletons of a large fchalicothere (fikforo- 

 pus, Fig. 130, p. 240) have been obtained, an animal which 

 considerably exceeded a large horse in bulk and stature. In 

 structure this genus had departed less widely from the normal 

 perissodactyl type than the genera of the European Miocene 

 and Pliocene above described and was in many respects more 

 primitive. It could not, however, have been directly ancestral 

 to the European forms, though indicating in a general sort of 



way what the ancestral 

 type must have been. 

 '\Moropus had a relatively 

 small, slender and pointed 

 head, a long neck, much 

 longer than in the Euro- 

 pean genera, and long fore 

 legs ; the shorter hind legs 

 gave the back a steep in- 

 clination from the shoul- 

 ders to the rump. The pro- 

 portions of the head, neck 

 and limbs suggest those of 

 a giraffe, in less exaggerated 

 form, but the likeness is 

 more marked in the skele- 

 ton than in the restoration 

 and is at best a distant one. 

 The feet were armed with 

 the great claws characteristic of the suborder, but the fore foot, 

 in addition to the three functional toes, had a long splint, 

 representing the rudimentary fifth digit ; of the first, or poUex, 

 no trace remained. The perissodactyl plan of symmetry had 



Fig. 185. — Leftmanusof lower Miocene fchal 

 icothere {^Moropus). (After Peterson.) 



