538 



HISTORICAL GEOLOGY 



Some (Pareiasaurus, Fig. 501 A> B) were as large as rather small cattle, 

 about nine feet in length and standing about three and a half feet 

 high, but with short legs and small, peg-like teeth, showing that they 

 were herbivorous. They are believed to have been tortoise-like in 

 habits, and probably protected themselves by digging in the ground. 

 Associated with these in the same beds are carnivorous thero- 

 morphs (Fig. 502), some with skulls two feet in length, with long, 



Fig. 501. — A, skeleton, and B, restoration of the herbivorous mammal-like (thero- 

 morph) Pareiasaurus. The length is about eight feet. The surface ornamentation 

 of the restoration is entirely fanciful. (After Amalitzky.) 



tiger-like teeth. Attention has already been called to the fact that 

 as soon as herbivorous animals appear in any age, carnivores, often 

 closely related to the herbivores, also occur and prey upon their 

 less agile neighbors. So among the theromorphs we find some of 

 massive build being destroyed and devoured by their swifter, carniv- 

 orous relatives. 



I he theromorphs diverged with such rapidity in the Permian 

 that, by its close, various groups appeared, differing slightly from 

 one another, as has been seen. They survived the severe changes 



