214 



CEETACEOUS EEPTILES. 



[Ch. XI. 



flora as to point in the same direction in regard to the 



existence of a high temperat 



They contain a lar 



ge 



number of dicotyledonous angiosperms, whereas the Lower 

 Cretaceous rocks are characterised by the absence of these 

 last; and by a pred< 



mmance 



an araucarian type, and of ferns referred by some botanists 

 to genera which favour the hypothesis of a warm climate. 



remains of the Upper Mio 



In reasoning on the 

 cene strata of Central and Southern Europe, we had the 

 advantage of drawing our inferences as to the high tempera- 



atmosphere and ocean from 



one-third of 



which were of living species, while our conclusions were con- 



firmed by contempo 



coral 



s 



besides the presence of apes 



genera of plants, insects, and 



mo 



The 



reptiles also were more numerous, some 



Miocene formatio 



temperat 



In the Lower 



1, crocodiles, chelonians, and large batra- 

 chians, and in the Eocene deposits the same genera of 

 reptiles, together with sea-snakes, bore testimony in like 



manner 

 rivers . 



the 



temperature 



seas, lakes, and 



Cretaceous reptiles. — When 



member of the Cretaceous series, or the Maestricht chalk, as 

 it is called, we find a similarly marked development of reptile 

 life in regions where nothing analogous is now to be met 



with. Thus, in latitude 51° N 



Mount, Maestricht 



aquatic 



Mosasaurus 



which was twenty-four feet in length. The same genus 

 appears in the American chalk, from the various divisions of 

 which Dr. Leidy has also obtained more than twenty genera 

 of reptiles, most of them extinct, but some, like the tortoises 

 {Trionyx and Emtjs),nn& the crocodiles of living types.* Several 

 of the crocodiles of this age, both in Europe and America, are 

 proccelian, that is to say, they have the anterior portion of 

 each vertebra concave, and the posterior part convex, in which 

 respect they agree anatomically with the existing species, and 

 are contrasted with a large number of the fossil genera of 

 that family. The reader will observe, on consulting Owen's 



* Leidy, Cretaceous Reptiles of United States. Smithsonian contribution, 1 865. 





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