Allosaurus, late Jurassic carnivorous dinosaur of the W United States. Specimens of 30 to 40 ft (9 to 12 m) have been found. It had stong hind legs, smaller sharply clawed forelimbs, two small horns directly above the eyes, and expandable jaws that could widen to consume large pieces of meat.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.