THE PERMIAN PERIOD 



673 



in South Africa (Karoo beds 1 ), but they have been found also in 

 Europe. 



The rapid and diverse deployment of the early reptiles in a period 

 of general life-impoverishment is not a little remarkable, but as the 

 reptiles were air-breathers, the key to their rise may lie in a more 

 oxygenated atmosphere, a point to which we shall return. 



Fig. 460. Palwohatteria lonyicaudata, a primitive diapsidan of the order 

 Protorosauria, about J/^ natural size. (Restoration by J. H. McGregor.) 



(Restoration by McGregor.) 



natural size. 



The Permian of Texas and Oklahoma affords the richest Per- 

 mian vertebrate fauna now known. In contrast with the verte- 

 brate fauna of the Pennsylvanian system, the Permian vertebrate 

 fauna of North America is so unlike the corresponding faunas of 

 other continents as to imply the absence of migration of land 

 animals between North America and other continents. This isola- 



1 The Karoo beds, so wonderfully rich in significant vertebrate remains, 

 are regarded as Permian in part, and Triassic in part. Broom, Geol. of Cape 

 Colony, 1905, pp. 228-249. 



