The legs are adapted for running, but not extremely so. They had strong arms, probably used to wrestle prey as the teeth bit in. The structure of an "Allosaurus" suggests a strongly-built general all-round predator. This is a different from a tyrannosaur like "Albertosaurus", which was better adapted for running on open ground. Tyrannosaurs, with their small two-fingered hands, would use their heads for killing prey, and for head-butting rivals.