As an early crocodile relative, its skull featured more crocodilian characteristics than its earlier ancestors; it had short jaws that broadened out at the base of the skull, providing a large surface to which its jaw muscles could attach. This increased the maximum gape of the animal's mouth and the force with which the jaws could be closed. The dentition of the animal also resembled modern crocodiles, including the teeth in the lower jaw that fitted into notches on either side of the upper jaw when the mouth was closed. It also possessed a powerful tail which later developed into a propulsion mechanism through water in its descendants.
Three species of Protosuchus have been described: the type species P. richardsoni  from Arizona, USA, P. micmac  from Nova Scotia, Canada and P. haughtoni  from South Africa.