ADAPTIVE RADIATION OF REPTILES 



195 



America, Europe, and Africa, as well as our first glimpses of the 

 early marine life of North America. In Jurassic time deposits 

 at the bottom of the great interior continental seas give us the 



TERRESTRIAL AND 

 FLUVIATILE 



N. AMER. [ EUROPE I AFRICA ] S. AMER. 



N. AMER. I EUROPE I AFRICA 



QUATERNARY 



LOWER 

 CRETACEOUS 

 (COMANCHEANt 



r^^^SlA 



SECOND REPTILIAN SEA FAUNA 

 IPLESIOSAURS AND ICHTHYOSAURS) 



Fig. 



73- 



Geologic Records of Reptilian Evolution, Terrestrial and 

 IMarine. 



Shaded areas represent the geologic vistas of reptilian life which have been discovered 

 from fossils entombed in ancient terrestrial, fluviatile, and marine habitats of 

 different portions of the northern and southern hemispheres. 



Triassic. We begin with the deposits of the continental surfaces of North America, 

 Fvurope, and Africa. During Triassic time the first dinosaur stages appear, as well 

 as some of the semi-aquatic forms which frequented flu\aatile regions, while the primi- 

 tive ICHTHYOSAURS Were then fully adapted to marine life. 



Jurassic and Lo\\^r Cretaceous. We continue with geologic vistas of the succeeding 

 marine life and the evolution of the second reptilian sea fauna, indicated by the 

 shaded areas of the Jurassic and the Lower Cretaceous of North America and Europe. 

 The remains of these animals are found in the deposits of deep or shallow sea waters. 

 There is one great vista, the second dinosaur stages, which includes the terrestrial 

 dinosaurs known as Sauropoda, found in Upper Jurassic and Lower Cretaceous de- 

 posits in North America, Europe, Africa, and South America. 



Upper Cretaceous. Then there was a long interval, followed by the final dinosaur 

 stages and a long vista of the terrestrial reptilian life of Upper Cretaceous time, especi- 

 ally in North America. Contemporary with this is the final reptilian sea fauna. 



Chart by the author. 



second reptilian sea fauna of plesiosaurs and ichthyosaurs within 

 the continents of North America and Europe. The story of the 

 marine pelagic evolution of the reptiles is continued with some 

 interruptions through the Lower Cretaceous into the final rep- 



