The skull is more solid, the jaws much deeper and more powerful, the fore limb much smaller, the tail shorter, the hind limb straighter and the foot bones more compacted so that the animal was more strictly "digitigrade," approaching the ostriches more closely in this particular.
[Illustration: Fig.

16 .-- SKELETON OF TYRANNOSAURUS IN COMPARISON WITH HUMAN SKELETON.] This animal probably reached the maximum of size and of development of teeth and claws of which its type of animal mechanism was capable.

Its bulk precluded quickness and agility.

It must have been designed to attack and prey upon the ponderous and slow moving Horned and Armored Dinosaurs with which its remains are found, and whose massive cuirass and weapons of defense are well matched with its teeth and claws.

The momentum of its huge body involved a seemingly slow and lumbering action, an inertia of its movements, difficult to start and difficult to shift or to stop.