THE AGE OF REPTILES 51 



During Jurassic times all these orders of reptiles waxed i)r()s- 

 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 disap[)eared 

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



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Fig. 28. — Restoration of Dimcirodon, 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 Hngered 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. 



