PRIMEVAL MAN 233 



of their birth, although not until they had sent 

 branches to Asia and South America, where 

 their descendants still survive. 



Two other grass-eating beasts, of large size 

 although smaller than the above were also 

 plentiful. One, a bison, bigger, straighter- 

 horned and less specialized than our modern 

 bison, represented the cattle, which were among 

 the animals that passed to America over the 

 Alaskan land bridge in Pleistocene time. 



The other was a big, coarse-headed horse, 

 much larger than any modern wild horse, and 

 kin to the then existing giant horse of Texas, 

 which was the size of a percheron. The horses, 

 like the camels, had gone through their develop 

 mental history on this continent, the earliest 

 ancestor, the little four-toed &quot;dawn horse&quot; of 

 the Eocene, being likewise the size of a jack- 

 rabbit. Through millions of years, while myr 

 iads of generations followed one another, the 

 two families developed side by side, increasing 

 in size and seemingly in adaptation to the envi 

 ronment. Each stock branched into many dif 

 ferent species and genera. They spread into the 

 Old World and into South America. Then, sud 

 denly, --that is, suddenly in zoologic sense 

 both completely died out in their ancient home, 

 and the horses in South America also, whereas 



