Such movements are widely different from the agile swiftness which we naturally associate with a beast of prey.

But an animal which exceeds an average elephant in bulk, no matter what its habits, is compelled by the laws of mechanics to the ponderous movements appropriate to its gigantic size.

These movements, directed and controlled by a reptilian brain, must needs be largely automatic and instinctive.

We cannot doubt indeed that the Carnivorous Dinosaurs developed, along with their elaborately perfected mechanism for attack, an equally elaborate series of instincts guiding their action to effective purpose; and a complex series of automatic responses to the stimulus afforded by the sight and action of their prey might very well mimic intelligent pursuit and attack, always with certain limits set by the inflexible character of such automatic adjustments.
But no animal as large as _Tyrannosaurus_ could leap or spring upon another, and its slow stride quickening into a swift resistless rush, might well end in unavoidable impalement upon the great horns of _Triceratops_, futile weapons against a small and active enemy, but designed no doubt to meet just such attacks as these.

A true picture of these combats of titans of the ancient world we cannot draw; perhaps we will never be able to reconstruct it.