75o ARTIODACTYLS xxxi. 4- 



hippopotamuses (Figs. 496-7), classed together as an infraorder 

 Ancodonta of the Suiformes. They have an enormous barrel-like 

 thorax, with large lungs, short, relatively thin legs with four digits, 

 and a complete dentition with low-crowned bunodont molars, wearing 

 to a foliage pattern. The stomach is enormous and partly divided. 



Fig. 496. Hippopotamus, Hippopotamus. (From photographs.) 



Fig. 497. Skeleton of the hippopotamus. (From Owen, The Anatomy of Vertebrates, 

 Longmans, Green & Co.) 



There are many specializations for life in the water, including eyes, 

 ears, and nose on the top of the head, muscles for closing the nostrils, 

 and a broad muzzle. They can remain submerged for five minutes. 

 Modern hippopotamuses are found only in Africa, but they were 

 widespread throughout the Old World until recent times. 



5. *Oreodonts 



The oreodonts were abundant and successful herbivores, living in 

 North America from the Eocene to the early Pliocene (Fig. 493). 

 They had long bodies and short legs and perhaps somewhat resembled 



