FOSSIL VERTEBRATES — REPTILIA 637 
Jurassic reached a very great development, both in numbers and 
in diversity of forms. 
Brontosaurus is from the upper Jurassic, in the vicinity of 
Lake Como, in Wyoming. It is the largest Dinosaur known, as 
well as the largest of the animal creation; the whole beast, from 
tip of snout to tip of tail, measured nearly sixty feet. The head 
was very small in proportion to the rest of the body, being less 
than the fourth cervical in size. The tail and the neck were 
long and quite strong. The tail was over half as long as the 
rest of the body; the dorsal vertebre had a short antero-pos- 
terior extent, but were quite broad. A hole under the transverse 
process of each side opened into a large cavity in the body of 
the vertebra, probably for the purpose of reducing weight. The 
pectoral girdle is represented by the usual elements, but the 
coracoid is very much smaller than the scapula and the sternum 
is composed of two pieces, one on each side of the median line 
as in the embryos of birds. The neural canal is greatly enlarged 
in the sacral region; this enlargement begins even in the cervical 
region, so that it would have been possible to have drawn the 
whole of the brain down through the neural canal. 
It is difficult to see how an animal that had reached the 
unwieldy size of the Brontosaurus could have supplied itself with 
food; the very small head and rather weak dentition would seem 
to render the actual task of getting a sufficient supply of food 
into the enormous body a very difficult one, even granting that 
the food was most plentiful; but if the animal was compelled to 
search to any extent for its supplies the work must have been 
an almost constant one. This is especially true because the food 
was entirely vegetable, and the proportion of such food neces- 
sary to support a body is much greater than the more condensed 
food of the carnivorous forms. The animal was in all probability 
semi-aquatic in its habits and lived for a good part of the time 
in the waters of the oceans and the lakes of the later Jurassic and 
the early Cretaceous time. That they suffered much from their 
great bulk is evident from the condition in which the skeletons 
are found; they are in many cases complete and undisturbed, 
