8.5 to 9 meters but fragmentary remains indicate individual up to 12 meters long
North America (mostly)
Allosaurus were big, efficient hunters that reigned as top predators during the Late Jurassic Period across North America and parts of Europe, and possibly even Africa. They were the most common large predators in North America 150 million years ago, reaching an impressive 9 metres in length and weighing up to 1.5 tonnes. These carnivorous dinosaurs could rip and tear chunks out of the large plant-eating sauropods and stegosaurs of the time. The enormous jaw was filled with long, serrated, back-curving teeth. Near perfect examples of this classic theropod dinosaur were discovered in Wyoming and called Big Al and Big Al Two. Allosaurus fossil remains are extremely rare outside America, nevertheless a handful have been found within Europe and a collection of theropod fossils in Africa may belong to Allosaurus.[152-144].
In the episode Fight for Life, it is seen attacking a mixed herd of stegosaurus and camptosaurus. But the attempt failed, resulting in injury from a Stegosaurus, but miraculously surviving. Later, the same Allorsaurus or a different one finds two camptosaurus away from the herd and attacks them. In this episode, research of the time suggested that it killed its prey using its upper jaw like an axe. The hunt is successful, but it’s kill was stolen by a large Saurophaganax, another large carnivore in the region.