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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.
This entry comes from Encyclopædia Britannica Concise. For the full entry on Allosaurus, visit Britannica.com.
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