Animals Before Man 



of tlie sea ; the abundant aquatic vegetation 

 disappeared, and the lumbering sauropods, ac- 

 customed to a life of ease, failed to adaj^t them- 

 selves to changing conditions and one by one 

 dropped by the wayside. 



The flesh-eating dinosaurs, Theropoda, as 

 might have been expected from their habits, 

 are of moderate size, small if compared ^^^th 

 their great relatives, although the hind leg of 

 Allosaurus was 7 feet long,^ and the entire 

 animal from 15 to 25 feet in length. Their 

 teeth were simple in structure, but long, slight- 

 ly curved, and compressed, with edges like 

 extremely fine saws. As in other re23tiles, 

 teeth w^ere renewed as fast as worn out, and 

 as this haj)pened at irregular intervals it gave 

 the row of teeth a very jagged apjDearance. 

 The limb bones were hollow, a characteristic 

 of active creatures, though found in a few 

 other dinosaurs, the claws sharp, in some spe- 

 cies very much curved and very bird-like. 

 The great claws of Ceratosaurus, the nose- 



* This, of course, in a full-grown animal ; the leg-bones range 

 from that downward. 



164 



