Proexochokefalos
Proexochokefalos is an extinct genus of machimosaurid teleosauroid from the Middle to Late Jurassic of France and Switzerland. In life, it was a large marine reptile that would have fed on other large animals.
History
The type species, P. heberti, was originally named "Steneosaurus" heberti by Morel de Glasville in 1876 from a roughly 1.1 meter long complete skull and mandible found in the Callovian aged Marnes de Dives near Villers-sur-mer in the Calvados department of Normandy, France. The genus Steneosaurus was used as a longtime wastebasket taxon for various teleosauroid specimens and had more than a dozen species. The type species, Steneosaurus rostromajor is undiagnostic, making the genus and species dubious and invalid. Additionally, many species of so called "Steneosaurus" were found to be quite different and unrelated to one another, thus needing new generic names.In a study by Michela Johnson and colleagues in 2020, "Steneosaurus" ''heberti was reclassified into the new genus Proexochokefalos, resulting in the new combination Proexochokefalos heberti. The species "Steneosaurus" depressus was also found to be a junior synonym of P. heberti. Another species referred to the genus, Proexochokefalos cf. bouchardi'' is known from remains from the Calcaire de Caen, France, and Reuchenette Formation, Switzerland.
Classification
Proexochokefalos is a member of the family Machimosauridae, a group of large-bodied sea going reptiles. They are known for their robust skulls, powerful jaws, and heavily built bodies, and were among the top predators in their ecosystems. Proexochokefalos possesses an intermediate morphology between more basal and gracile machimosaurids and the larger and more heavily built members of the tribe Machimosaurini.The cladogram below is from an analysis conducted by Johnson and colleagues in 2020.