The left and right lower jaws are relatively long and loosely attached to each other at the symphysis (chin). There are 14 teeth in the dentary, the main tooth-bearing bone of the lower jaw. This bone has a straight or slightly convex lower edge and expands upwards at the chin, unlike "Saurosuchus". The splenial, which lies on the inner surface of the dentary, is unusually elongated in "Prestosuchus" and extends as far forward as the second tooth in the jaw. The rear of the dentary has a shallow incision which defines the front edge of the rounded mandibular fenestra. The lower edge of the mandibular fenestra is mainly bound by the angular, while the surangular forms its upper border. Bones at the rear of the lower jaw have proportions and structures similar to other loricatans. Such structures include a shelf at the rear of the surangular and a thick articular bone which has a tall retroarticular process with an inner prong pierced by a "chorda tympani" foramen.