THE AGE OF REPTILES 



Stegosaurs, which were also four-footed. They were 

 curiously armoured, and formed a group of very remark- 

 able creatures found in England and Western America. 

 While they were less gigantic than some of those we have 

 just described, they found compensation in protective 

 plates, spines, and similar modes of defence. A Stego- 

 saurus found in Wyoming was probably the most hideous 

 to look upon ; but like his relatives he had an extraordi- 

 narily small head and brain, and was a sluggish creature 

 depending on his ugliness and armour for protection. 

 Very likely this small size of the brain of great extinct 

 reptiles had to do with the fact of their ceasing to 

 exist. Animals with bigger and ever-increasing brains 

 outdid them in the struggle for existence. 



It has already been noted that the crowding of the 

 land may have led some reptiles to take to the sea. The 

 same influence may have led others to take to the air and 

 thereby escape the monsters of the swamps, jungles, 

 and forests. Whatever the cause, the most striking and 

 wonderful feature of this period was the development of 

 flying reptiles. They had just been seen in the Trias. 

 In the Jurassic they appeared fully developed. They 

 doubtless sprang from some agile hollow-boned saurian, 

 more or less akin to the slender leaping Dinosaurs. Be- 

 tween the ponderous Brontosaurs and the airy Ptero- 

 dactyls was the most striking of contrasts. At first these 

 bird-like reptiles were small, but later their wings had a 

 spread of as much as twenty feet, veritable flying dragons. 

 They were not adorned with feathers, but like bats had 

 leathery membranes stretched from the fore limbs to the 



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