rect 3 4 498 374 Allosaurus rect 995 4 498 374 Giganotosaurus rect 249 900 750 374 Polar Allosaur desc top-left Allosaurs were a family or a clade of theropod dinosaurs. Although they originated in the Northern Hemisphere, the last allosaurs were found in the south. The members of this group were characterized by large, well-developed front limbs, armed with powerful claws, and long and relatively narrow jaws, studded with thin, blade-like teeth - perfect for slicing teeth but useless against armored skin and bone, unlike the teeth of Tyrannosaurus rex.