Anatomy
Although not as heavy as the massive tyrannosaurs, Allosaurus was big for a carnosaur. Its long legs and stiff tail made it a swift straight-line pursuit predator.
It’s head was long, narrow, tapered, and mounted on a sinuous but muscular neck. Relatively weak jaw muscles, a wide gape, and small serrated teeth suggest that it carved pieces off big prey by dragging its upper teeth through their flesh. The fore-limbs were small but still strong enough to drive their three hooked claws into a victim and hang on as it struggled. The feet, each with three clawed toes and a dewclaw, also seem to have been used to restrain prey.
Two bony crests ran along the top of the skull, with a horn-like projection before the eyes. Lizard-like lips would have sealed the mouth to prevent the teeth from being damaged by dry air. Only a few skin samples have been identified, which all show small scales. Although it is possible that some parts had proto-feathers, they would not have been necessary for insulation, so it is likely that the overall appearance would have been that of a lizard with bird-like legs.
Behavior and Habitat
The favorite prey of Allosaurs seems to have been large sauropods, which they hunted in the warm fern prairies and floodplains of the late Jurassic. They had a wide range, often living in environments which would have varied seasonally from wetland to almost desert-like conditions.
Their brains weren’t especially large and there is little evidence of social behavior, so it is likely they were solitary hunters who used a simple stalk-and-dash strategy to take slower prey.