Its pineal foramen was large, and anteriorly placed, with its anterior edge bordered by the frontal bones. Unlike most of its relatives, its ectopterygoid is not known and may not be present, as in Protenodontosaurus. The P. alpinum species had decidedly elongated, posterior, tooth-bearing plates for crushing the shellfish that formed its diet.
Its pineal foramen was prominent and located at the front, bordered by frontal bones. Unlike most of its kin, it lacked an ectopterygoid or possibly didn't have one, as seen in Protenodontosaurus. The P. alpinum species had notably elongated plates with teeth at the back to crush shellfish that made up its diet.