106 GREAT DINOSAURS 
skeletons of several kinds of dinosaurs obtained from the cretaceous 
formations of Alberta, and mounted as they lay when three million 
years ago, they settled to the bottom of a western lake and were gradually 
covered with sand and mud and slowly turned into stone. 
The gigantic skeleton in the center of the hall is the huge extinct 
reptile, the dinosaur Brontosaurus, found in the Jurassic beds of Wyom- 
ing. It is the only mounted specimen of its kind in the 
world and more than two-thirds of the skeleton is the 
original petrified bone. It is sixty-six feet eight inches in length, 
sixteen feet in height and is estimated to have weighed, when alive, 
Brontosaurus 
Section of the skin of Trachodon showing the small scutes with which the animal was covered. 
About natural size. 
thirty-five tons. Brontosaurus is one of the largest giant reptiles and 
as is indicated by its teeth was herbivorous, probably living on the rank 
water weeds of the nearly sea-level marshes of Wyoming. Contrasted 
with the herbivorous Brontosaurus is the carnivorous dimosaur Allo- 
saurus, mounted to represent the animal feeding on the 
fallen carcass of a Brontosaurus, upon which it preyed. 
This is not a fanciful mounting, for these very skeletons were found 
in close proximity to each other in the Jurassic beds of Wyoming, and 
the skeleton of the fallen Brontosaurus shows gouges made by the 
teeth of Allosaurus as it tore the flesh from its victim. 
Near the Allosaurus group is a skeleton of Tyrannosaurus, the last 
and most powerful of the carnivorous dinosaurs. This huge carnivorous 
reptile rivalled the Brontosaurus in size and was far more 
active and ferocious, preying upon the duckbilled horned 
or armored dinosaurs which lived at the same time. 
Allosaurus 
Tyrannosaurus 
