PRIMITIVE REPTILES 



A REVIEW 



S. W. WILLISTON 

 From the Paleontological Laboratory, University of Chicago 



ONE FIGURE 



The evidence seems now conclusive that the extensive Ameri- 

 can reptihan fauna hitherto called Permian is in part of upper 

 Pennsylvanian, in part of lower Permian age, and, therefore, 

 is the oldest known. From other parts of the world there are 

 only a few known forms supposed to be of equivalent, or approxi- 

 mately equivalent, age, the chief of which, if not the only ones, 

 are Stereosternum and Mesosaurus from the Santa Catherina 

 System of Brazil, the latter genus also from the upper Dwyka of 

 South Africa. From immediately superjacent beds in South 

 Africa, doubtless of lower Permian age, but one or two reptiles 

 are known, Archaeosuchus and Eccasaurus, referred by Broom, 

 the former at least, to the dinocephalian group of the Therapsida. 

 From the Beaufort beds, upper and lower, of Africa, numerous 

 genera of reptiles are known, referred to the Cotylosauria and 

 Therapsida. Because of the close affinity or identity of some 

 of these genera with those found in Russia, they doubtless should 

 all be considered of upper Permian age, as distinguished from 

 lower Permian. From the Rothliegende of Germany and France, 

 of lower Permian age, the following genera of reptiles are known : 

 Stephanospondylus, Phanerosaurus, Datheosaurus, Stereorhachis, 

 Kadaliosaurus, Callibrachion, Aphelosaurus, and Paleohatteria 

 (Haptodus). Leaving Archaeosuchus and Eccasaurus out of 

 account in the following discussion, the present paper will deal 

 with the carboniferous and lower Permian reptiles only, including 



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