EARLIEST REPTILES 



189 



ning of the Permian Epoch. 

 The contemporaneous evo- 

 lution of the pro-ReptiUa, 

 traced in a continuous earth 

 section from the base of the 

 Permian to the Lower Trias- 

 sic, as successively explored 

 by Bain, Owen, Seeley, 

 Broom, and Watson, has re- 

 realed a far more extensive 

 and more varied adaptive 

 radiation of the reptiles than 

 that which is known on the 

 American continent. Al- 

 though the adaptations are 

 chiefly terrestrial, we trace 

 certain strong analogies if 

 not actual relationships to 

 the Permo-Triassic reptiles 

 of North America. 



While the drying pools 

 and lagoons of arid North 

 America were entombing the 

 life of the Permian and 

 Triassic Epochs, there were 

 being deposited in the Karoo 

 series of South Africa some 

 9,500 feet of strata consist- 

 ing of shales and sandstones, 

 chiefly of river flood-plain 

 and delta origin, and rang- 

 ing in time from the basal 



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CARBONIFEROUS 



Fig. 



The Fin-Back Permian 

 Reptiles. 



Restorations (middle and upper figures) of 

 the giant carnivorous reptiles of northern 

 Texas in Permian time; the large-headed 

 Djmctrodon and the contemporary small- 

 headed Edaphosauriis cruciger. In both 

 animals the neural spines of the vertebrae 

 are greatly elongated, hence the popular 

 name "fin-back." Skeleton of Dimctrodon 

 (lower) in the American Museum of Natural 

 History. Restorations for the author by 

 W. K. Gregory and Richard Deckert. 



