ANIMALS OF THE PAST 



347 



Animals of the Mesozoic Era 



In this era the reptiles increased in size, variety, and 

 nmnbei'. Fisiies, insects, and niollusks became abundant 

 and various, antl more nearly apjn-oached the living forms 

 of these groups. Sea 

 urchins (Fig. 226) 

 much like our pres- 

 ent ones appeared 

 in abundance. The 

 lamp shells dimin- 

 ished in nimilier of 

 species, but the 

 squids, cuttlefishes, 

 and other niollusks 

 appeared anil peo- 

 pled the seas. Their 

 shells are found in 

 immense numbers 

 and are well preserved. The trilobites having disappeared, 

 crabs and lobsters came in their places. 



Reptiles. — It is auKjng these animals that the greatest 

 changes are noted. There existed at this time three classes 

 of reptiles : land i-eptiles, sea reptiles, and flying reptiles. 

 They were very abundant and of extraordinary size and 

 Variety. 



Sea urcliiii of iiu'sozoic lime.s 



Fig. 227. — Sen reptile of luesozoic times. 



