FAUNAL RELATIONS OF EARLY VERTEBRATES 3907 
from the eastern continent. Morosaurus mimics Cetiosaurus, Camp- 
tosaurus Iguanodon, Stegosaurus Omosaurus, Allosaurus Megalosau- 
rus, etc. We are confident then that during Morrison times there 
was freedom of migration between the eastern and western continents, 
so free that nothing distinctive of our fauna had been developed 
through isolation. Here now we find for the first time meager repre- 
sentatives of the first turtles, of a single type, which had been known 
on the eastern continent since Middle Triassic times, almost the first 
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 odlite 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 no 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 
