Animals Before Man 



zona, and New Mexico, are sufficient to show 

 that already this group of animals was widely 

 distributed. One of these, dubbed Paleocto- 

 nus by Professor Cope, was, to judge from the 

 bones, rather small and slender in build, though 

 its formidable teeth, the largest of them 2^ 

 inches long and 1 inch through, indicate a 

 large head and rapacious habits. 



A word or two may be said of the inverte- 

 brate life of the Permian and Trias, for this 

 also took part in the general progress and trans- 

 formation. The dwindling race of trilobites 

 came to an end in the Permian, while the curi- 

 ous brachiopods, like the sharks, suffered a 

 sweeping reduction in numbers from which 

 they never recovered. " And it is not at all 

 improbable that the same causes similarly af- 

 fected these two very different races of marine 

 animals, and that the main factor which brought 

 about the great decrease was a lowering of the 

 temperature of the sea. The more familiar 

 bivalve mollusks, on the other hand, increased, 

 and the cephalopods developed new and more 

 complicated forms. It may be remembered 



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