Allosaurus Characteristics

Allosaurus measured up to 12 metres (39 feet) long and stood 10 feet (3 metres) tall at the hips. Allosaurus could typically weigh up to 4.5 tons. It was named 'different lizard' because its vertebrae was lighter than those of all other dinosaurs. Allosaurus was a typical large theropod, having a massive skull on a short neck, a long tail and reduced forelimbs. This dinosaurs most distinctive feature was a pair of blunt horns, just above and in front of the eyes. Although short in comparison to the hindlimbs, the forelimbs were massive and bore large, eagle-like claws. The skull showed evidence of being composed of separate modules, which could be moved in relation to one another, allowing large pieces of meat to be swallowed. The skeleton of Allosaurus, like other theropods, displayed bird-like features, such as a furcula (wishbone) and neck vertebrae hollowed by air sacs.

Allosaurus shared the landscape with several genera of giant sauropods such as Apatosaurus, Diplodocus and Camarasaurus as well as other herbivores such as Stegosaurus and Camptosaurus, all of which may have been potential prey to the Allosaurus.

More sparse finds of a smaller species similar to Allosaurus and dating from the Early Cretaceous of North America and Australia, indicate that this versatile hunter might have survived the mass extinction at the end of the Jurassic period.

Allosaurus is the most common theropod in the vast tract of dinosaur-bearing rock in the American Southwest known as the Morrison Formation. Remains have been recovered in Montana, Wyoming, South Dakota, Colorado, Oklahoma, New Mexico and Utah, in the United States. There have also been finds in Portugal. Allosaurus shared the Jurassic landscape with several other theropods, including Ceratosaurus and the massive Torvosaurus.

The Allosaurus dinosaur was named by Othniel Marsh in 1877.