Megalosaurus, a huge reptile, the type of a family Megalosauridae, in the carnivorous order Theropoda of the sub-class Dinosauria (q.v.), which occurs in Oolitic and Wealden deposits in England. M. Bucklandi, from the Stonesfield Slate (Bathonian) is estimated to have been 25 feet long and to have weighed two or three tons. It had only four toes to each foot, and, like many carnivorous mammals, was digitigrade, with prehensile claws. Its fore-limbs are very small and limb bones hollow; but both its thigh-bone and leg-bone are three feet in length; so that it probably walked erect. It has trenchant, curved, pointed, and finely serrated teeth, and fed probably on the molluscs, fish, and small rat-kangaroos on the shores of the lagoons by which it lived.