THE AGE OF REPTILES 



huge hind limbs, short fore limbs, narrow chests, and 

 pigmy skulls: 



Both branches of the reptilian horde, those representing 

 the saurians and those which were the forerunners of the 

 mammals, sent delegations to the sea before the close 

 of the Triassic period. The Ichthyosaurs represented 

 the more pronounced reptilian line ; the Plesiosaurs were 

 the representatives of the coming mammals. It is not 

 difficult to find good reason for this movement to the 

 sea. Besides the inevitable tendency of every masterful 

 race to invade all accessible realms, the renewed extension 

 of the sea that set in during the Triassic period and 

 became pronounced before its close, especially invited 

 this, for the shallow waters creeping out upon the land 

 with their now prolific life set tempting morsels before 

 the voracious reptiles, on the one hand, while on the 

 other, the reduction of the land area and the restriction 

 of their feeding-grounds, intensified by the multiplication 

 of the reptiles themselves, forced a resort to the sea. 

 One of the reptiles of this period, the Lariosaurus, shows 

 by its development how the change affected the reptiles. 

 In the earlier stages of the Trias it resembled a rather 

 swollen alligator with four limbs symmetrically situated 

 and used for crawling. In the later forms of these 

 reptiles the limbs were modified with paddles, and all 

 power to move about on land was lost. 



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