FOSSIL VERTEBRATES — REPTILIA 645 
Translating very freely from Zittel’s Handbuch, we have the 
following summary of the range and distribution of the Deno- 
SQUIS : 
In general we may say that Europe and North America were, during the 
Triassic, Jurassic, and Cretaceous times, the home and the region of the 
greatest development of the Dzzosaurs. From the East Indies only incom- 
plete remains are known from the Trias and the Cretaceous, and from South 
Africa, only enough remains to say that there were Dinosaurs there. In 
South America and Australia the remains of these animals are, as yet, com- 
pletely unknown. 
Although the largest number of forms as wel] as the most perfectly 
preserved remains are known from the United States, Europe affords 
many specimens of all the principal groups. The American Sauwrofoda are 
represented in Europe by Cetéosaurus, Ornithopsis and an incompletely pre- 
served Cretaceous form. The Zanclodontide parallel to some extent the 
Anchisauria. The Megalosauria of Europe are represented in this country 
by Alosaurus, Lelaps, and several less well-known forms. The Cera- 
fosauria are unknown in the Old World, and the Ceduria, hollow-boned 
forms, are represented by Calamospondylus and Aristosuchus. Tanystro- 
pheus belongs to both the Old and the New Worlds. The European Comp- 
sognathus is found in the Hallofus. Among the Predentata the Scelidosauria 
are confined to Europe while the S/egosauria are mostly American, Omo- 
saurus, if not a synonym of Stegosaurus, would be a European representative 
of this group. The forms from the Laramie Cretaceous are all confined to 
the American continent. 
From a geological standpoint the original distribution of the Dznosaurs 
was practically contemporaneous, though even in the Trias there were well 
defined areas containing differentiated forms, and this differentiation by local 
development was accentuated in the Jurassic and Cretaceous. Animals from 
the two continents frequently belong to the same families but seldom to the 
same genera and species. 
Perhaps the most peculiar thing about these forms is the 
sudden and complete destruction of the whole order at the end 
of the Mesozoic time. The Cretaceous rocks just at the end of 
the period show that there was a very large number of individ- 
uals as well as species, but the earliest of the Tertiary series are 
as free from their remains as the most recent formation. There 
is no cause for this sudden extinction of a great group unless it 
was a climatic one, and even this is not indicated by any change 
in the vegetable life of the two periods. 
