FAUNAL RELATIONS OF EARLY VERTEBRATES 171 



crocodiles, well known also there since Triassic times, but represented 

 here by a single form with relatively few individuals, of a distinctively 

 European genus. Nothing else save a single fragmentary bone of what 

 may have been a pterodactyl, and a recently discovered (Gilmore) 

 terrestrial rhynchocephalian, known over there from the Permian, 

 Trias, and Jurassic; not a nothosaur, so characteristic of the Euro- 

 pean Triassic land fauna, not a lizard, known from the Triassic of 

 Africa, not a bird, known from the Upper Jura of Solenhofen, prac- 

 tically nothing but dinosaurs, and mammals very closely allied 

 to the Kimeridge or Wealden mammals of Europe — the first known 

 multituberculates here, but known from the oolite there. Can one 

 conceive of more favorable conditions for the preservation of the 

 remains of all these creatures and of the small salamanders known 

 contemporaneously in Europe, than those which existed through 

 the thousands of miles of extent of low-lying, marshy lands of Morri- 

 son times ? It will not suffice to say that we may yet find them in 

 America. Under far less favorable conditions, apparently, bird 

 remains are found in the Upper Cretaceous of New Jersey, Kansas, 

 and Wyoming. 



The conditions and faunas of the Morrison times are continuous 

 throughout the Lower Cretaceous, so far as we know them; nothing 

 new, nothing different save the reappearance of the plesiosaurs, noth- 

 ing strange, nothing distinctive, and scarcely a type missing. 



With the Upper Cretaceous the meager fauna of the Dakota gives 

 only the footprints of a bird and a more distinctively terrestrial turtle. 

 In the Benton, aside from the marine plesiosaurs, which here reach 

 their culmination perhaps, and the ichthyosaurs, which now are 

 dying out here after their disappearance in Europe, we find the last 

 of the broad-nosed crocodiles (Coelosuchus) of ancient type, another 

 lingerer, which had apparently disappeared in Europe, and the first 

 of the slender-nosed crocodiles of olden type, their first appearance 

 here after their last records from the eastern continent. And with 

 them appears for the first time a new type of dinosaurs, the armored 

 polacanthids (Stegopelta) which had appeared in Europe in the 

 Wealden, but which is unknown from the earlier deposits of America 

 among all the vast numbers of dinosaurs. With the close of the Ben- 

 ton and the beginning of the Niobrara, we find the first appearance 



