n.
Large carnivorous dinosaur of a group similar to the tyrannosaurs , found as fossils primarily in Late Jurassic rocks of North America.
It weighed 2 tons (1,800 kg) and grew to 35 ft (10.5 m) long. Its well-developed tail, half of its total body length, probably functioned as a counterbalance for the body. Allosaurus walked on its two hind limbs and probably used the much smaller forelimbs for grasping. Equipped with powerful, flexible jaws, allosaurs likely preyed on medium-sized dinosaurs; they were possibly scavengers that hunted in groups. Some related allosaurs ( Giganotosaurus, Carcharodonotosaurus ) may have been larger than Tyrannosaurus rex .