THE AGE OF REPTILES 



51 



During Jurassic times all these orders of reptiles waxed pros- 

 perous and powerful, and branched out in many ways and in count- 

 less numbers; many new kinds of each appeared — the marine 

 crocodiles, the quadrupedal dinosaurs, etc. — but no order or sub- 

 order, so far as we know, disappeared before its close. And this 

 prosperity continued on into the Lower Cretaceous and for many 

 even into the Upper Cretaceous. The largest dinosaurs disappeared 

 in the Lower Cretaceous, so far as our knowedge goes, but the 



Fig. 28. — Restoration of Di met rod on, a pelycosaur reptile from the Permian of 

 Texas; about eight feet long. 



old-fashioned crocodiles continued on into the Upper, to give place 

 to the new-fashioned kinds. The ichthyosaurs lingered on for a 

 while on the western continent, but the mosasaurs appeared, and 

 the plesiosaurs reached their highest evolution and continued 

 to the end. The flying reptiles attained the zenith of their evolu- 

 tion, but disappeared before the close. The marine turtles attained 

 the maximum of specialization and size. The upright-walking 

 dinosaurs continued on unabated to the close of the period; and a 

 new kind of dinosaurs appeared near the end. 



