REPTILES 



367 



the largest of all four-footed animals. The long tail 



at one end is so like the long neck at the other, with its 



quite insignificant head, 



that we have to look 



twice at the skeleton of 



the Diplodocus to be sure 



which is which. The 



problem of feeding these 



vast creatures must have 



been a difficult one, and 



they possibly died out for 



lack of sufficient food, or 



it may have been because 



of disease or predatory 



enemies. Possibly the 



mammals took to eating 



their eggS Or yOUng. Even ZUtel's " Palteontologie " (after H. v. Meyer) 



iri their prime, these great FlG - J 44- Skeleton of a pterodactyl ; a fly- 

 . . . ... ing reptile, one of the Pterosauria. 



animals had terrible ene- 

 mies in other dinosaurs, which were carnivorous. This 

 we know from their sharp and powerful teeth, adapted 

 for holding and tearing flesh. These carnivorous dino- 

 saurs had the front legs adapted for grasping or tearing, 

 but not for walking. They walked on their hind legs, 

 which were mostly three-toed and resembled more or 

 less those of birds. Consequently, when their tracks 

 were discovered many years ago by geologists ("foot- 

 prints in the sands of time"), they were supposed to be 

 those of gigantic extinct birds. The armored dinosaurs 

 were grotesque creatures, with massive bony armor 

 plates, and crests or spines covering parts of the body 

 and tail. They were herbivorous, and were presuma- 

 bly protected by their armor from the attacks of the 

 carnivorous forms. Other dinosaurs had extraordinary 

 horns, recalling the rhinoceros. 



