The Life of Yesterday 



and their antiquity does not cause tliem to be 

 treated with respect. 



One of these ground sloths, Megalonyx, the 

 great-clawed, was found in Virginia and de- 

 scribed by Thomas Jefferson; but the more 

 common animal, that ranged from the Gulf to 

 Ohio and Missouri, was named Mylodon. These 

 animals belong to a group that is thought to 

 have originated in North America duiing the 

 Eocene period, and to have spread slowly 

 southward while the climate of the world 

 was mild and equable. Finding in South 

 America a favorable environment, plenty of 

 food and few enemies, the edentates increased 

 in size and multiplied in numbers, culminating 

 in the Pleistocene in such forms as megatheri- 

 um and the armadillo-like glyptodonts. A 

 return wave of migration brought these big 

 beasts into North America, where they may 

 have been contemporary with primitive man. 

 In South America remains of one species, 

 Grypotherium, have been discovered under 

 such conditions as to make it probable that the 

 animal was actually kept in a state of domesti- 



255 



