Allosaurus, the "Different Lizard," provides a "different" example of a ferocious predator than that of the Tyrannosaurus. Contrasting with the T. rex, the Allosaurus measured only three meters tall, just under twice the height of a human. It was still quite long at a maximum of 9-10 meters. Its notable skull ridges had several functions, such as acting as sun-shades and display items. Curiously, many skull fossils found exhibit odd imperfections, providing valuable insight into the paleo pathology of dinosaurs and its possible effects on creatures. Living at the top of its food chain, the menacing claws and jaws of the Allosaurus made it quite the predator long before the time of the Tyrannosaurus. Abundantly found in the Morrison Formation, it survived by preying upon large herbivores and possibly even some predators. It prowled the semiarid environments of present day America and Portugal alongside other predators like Ceratosaurus and Torvosaurus, but the three likely held separate niches. Living from the Kimmeridgian to early Tithonian eras of the Jurassic, Allosaurus had a delectable selection of prey. Paleontologists have found evidence that it hunted Stegosaurus and other members of its family for food and likely scavenged sauropod carcasses.