Article: Cranial osteology of the sauropterygian Plesiosaurus brachypterygius from the Lower Toarcian of Germany

An osteological re-study of the holotype skull of Plesiosaurus brachypterygius leads to a correction of several inaccuracies and misidentifications of the original description by von Huene and reveals additional facts on the cranial anatomy of this plesiosaur. Comparison with the type species, Plesiosaurus dolichodeirus, from the Lower Lias of England shows considerable differences in many parts of the cranial skeleton, even though the two species are generally so similar that their inclusion in the same genus proposed by von Huene, and agreed with by all subsequent authors, can be supported. Plesiosaurus brachypterygius is provisionally considered as a valid species distinguishable from the contemporaneous Plesiosaurus guilelmiimperatoris by its much shorter limbs, a difference that cannot be explained by ontogenetic variation as proposed by Storrs. Plesiosaurus brachypterygius was probably an ichthyophagous form that occurred rarely in the Posidonienschiefer fauna.