362 



GENERAL ZOOLOGY 



One species reached a length of more than twenty feet, and 

 stood eight feet high. 



Some of the ancient reptiles (the flying lizards, or ptero- 

 saurs, Fig. 187) were capable of flight by means of skin 

 stretched between the front and hind limbs and tail. Most 

 of the bones were hollow and the skull was quite bird-like. 

 Whether these characteristics can be taken to mean that 



the birds have de- 

 scended from these 

 flying reptiles is 

 doubtful, though it 

 has been asserted 

 by some paleontolo- 

 gists. It is perhaps 

 more likely that 

 these common 

 characteristics were 

 evolved to meet 

 similar conditions 

 in two different 

 groups, and that we 

 must look farther 

 back to find the an- 

 cestors of the birds. 

 Reptiles which are 

 apparently related 

 to the alligators and crocodiles, and to the turtles and tor- 

 toises, have also been found in the rocks of this period, so 

 that these groups are very ancient. Most of the lizards and 

 snakes belong to a later day, 



At the close of the Age of Reptiles a great upheaval of 

 land occurred in the west, forming the Rocky Mountain sys- 

 tem. After that disturbance, which ranks in importance with 

 the uplift at the close of Paleozoic Time, practically the 



FIG. 187. Restorations of Pterosaurs 

 (From Seeley's Dragons of the Air) 



