Identifier: waterreptilesofp1914will Title: Water reptiles of the past and present Year: 1914 (1910s) Authors: Williston, Samuel Wendell, 1851-1918 Subjects: Aquatic reptiles Publisher: Chicago, Ill., The University of Chicago Press Contributing Library: Boston Public Library Digitizing Sponsor: Boston Public Library

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Text Appearing Before Image: ion is yet provisional,representing merely the presentstage of our knowedge. The Pro-ganosauria and Protorosauria,including distinctively aquaticreptiles, will be more fullydescribed in the following pages.To give even a brief description ofthe more terrestrial reptiles of this,the earliest known reptilian fauna,would be beyond our purpose; theaccompanying life restorations bythe author of some of the moretypical and better known forms,based upon nearly perfect skele-tons, will suffice. From the reptiles and amphib-ians of the Lower Permian of Texas and New Mexico to theichthyosaurs of the Middle Triassic of California there is acomplete gap in the records of the land life of North America.We do not know what became of all the remarkable animalsof the Permian. There are few traces of their descendants else-where known, unless it be in South Africa. From the Middleand Upper Permian of South Africa and Russia, a marvelous rep-tilian fauna has been made known in recent years. More than a

Text Appearing After Image: Fig. 26.—Captorhinus, a cotylosaurreptile from Texas, about one-fourthnatural size. 50 WATER REPTILES OF THE PAST AND PRESENT hundred species of six or seven groups, and at least two orders havebeen described. Of these the Cotylosauria are the continuationof the American order, but include more specialized forms, thePareiasauria and the Procolophonia, all of them, like the moreprimitive American forms, characterized by the imperforatetemporal region. The Therapsida, likewise, seem to be the con-tinuation of the American Theromorpha, so closely allied to themthat it is difficult to draw a distinguishing line between them.On the other hand, these African reptiles merge through theTheriodontia into the mammals in the Triassic. They are all

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