CHAPTER IX. 



RELATION OF NORTH AMERICA TO THE OTHER CONTINENTS IN PERMO- 



CARBONIFEROUS TIME. 



The Permo-Carboniferous fauna has been traced from New Mexico to 

 Prince Edward Island, but has not been recognized with any certainty in the 

 European Permian, as shown by Case.^ The only European genus which has 

 been recognized as belonging to the Texas fauna is Edaphosaurus, described 

 by Fraas from Bohemia and by Jaekel from the vicinity of Berlin.'' Von 

 Huene has described two forms, Anomosaurus and Ctenosaurus, which he con- 

 sidered as related to the Pelycosaurs, but which, occurring as they do in the 

 middle and upper Triassic , can be regarded only as widely removed descendants, 

 if related at all.'' 



The resemblance of Crossotelos to Urycordylus and Keraterpeton can not 

 be considered as genetic. 



The fauna of North America was, so far as the author can see, an isolated 

 one, prevented from any mixture with other groups of animals by an isolation 

 of the continent from Europe nearly as complete as that of to-day. The 

 author is in accord with WiUiston in this matter, who in 1909 expressed him- 

 self concerning the fauna as found in Texas as follows -^ 



"As a continent I believe that the land of America was absolutely and continu- 

 ously isolated, so far as the intermigrations of land forms were concerned, from some 

 time before the close of the Pennsylvanian till well into Triassic times, as they reckon 

 in Europe. 



"The fauna was literally sui generis, and I may almost say sui ordinis. But 

 two or three genera of two types out of the scores of genera known from these 

 regions can be correlated as showing resemblances — family resemblances, I mean — 

 with foreign forms. And both of these types had made their appearance, admittedly 

 nowhere in America, before the close of the Pennsylvanian, one the derivation of 

 Upper Carboniferous, possibly sub-Carboniferous stock, the other a later develop- 

 ment, and both continuing for a brief period in Europe during the Permian times. 

 Of all the remainder of the air-breathers not one can be compared with forms known 

 elsewhere in the world, save in general characters — ordinal characters at best. 



"These facts can mean but one thing: the faunal isolation of land and fresh- 

 water vertebrates during all of the so-called Permian times in America. * * * 



' ' Upon the whole, then, our Permian fauna is sharply, and almost completely, 

 distinguished from any supposed contemporaneous or indeed any fauna known 

 elsewhere, and may have been evolved wholly in America from known Pennsyl- 

 vanian forebears." 



" Case, Jour. Geol., vol. xxvi, No. 6, pp. 572-580, 1908. 



^ Jaekel, Naosaurus credneri, in Rothlicgenden v. Sachsen. Monatsb. d. Deutsch. Geol. Gesellsch., 

 1910, Nos. 8-10, pp. 226-535. 



" Described and discussed in Carnegie Inst. Wash. Pub. 55, pp. 33-57. 

 '^ WiUiston, Jour. Geol., vol. 17, p. 389, 1909. 



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