Animals Before Man 



of the sea ; the abundant aquatic vegetation 

 disappeared, and the lumbering sauropods, ac- 

 customed to a life of ease, failed to adapt 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 with 

 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 reptiles, 

 teeth were renewed as fast as worn out, and 

 as this happened at irregular intervals it gave 

 the row of teeth a very jagged appearance. 

 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 



