Proexochokefalos

{{Short description|Extinct genus of reptiles}} {{Automatic taxobox | fossil_range = Callovian-Kimmeridgian ~{{fossilrange|165|152}} | image = Proexochokefalos.png | image_caption = Skull of ''P. heberti '' | display_parents = 2 | authority = Johnson ''et al.'', 2020 | taxon = Proexochokefalos | type_species = {{extinct}}'''''Proexochokefalos heberti''''' | type_species_authority = (Morel de Glasville, 1876) | synonyms = *''Steneosaurus'' cf. ''bouchardi'' Sauvage, 1872 | subdivision_ranks = Other species | subdivision = *{{extinct}}''P. cf. bouchardi'' (Sauvage, 1872) }} '''''Proexochokefalos''''' (meaning "big head with big tuberosities") is an extinct genus of machimosaurid teleosauroid from the Middle to Late Jurassic of France and Switzerland.<ref name="Teleosauroidea">{{cite journal |last1=Johnson |first1=Michela M. |last2=Young |first2=Mark T. |last3=Brusatte |first3=Stephen L. |title=The phylogenetics of Teleosauroidea (Crocodylomorpha, Thalattosuchia) and implications for their ecology and evolution |journal=PeerJ |date=2020 |volume=8 |article-number=e9808 |doi=10.7717/peerj.9808|pmid=33083104 |pmc=7548081 |doi-access=free }}</ref> In life, it was a large marine reptile that would have fed on other large animals.<ref name=eco/>

==History== thumb|left|''P.'' cf. ''bouchardi'' skull The type species, '''''P. heberti''''', was originally named "''Steneosaurus''" ''heberti'' by Morel de Glasville in 1876 from a roughly 1.1 meter (3.6 foot) long complete skull and mandible (MNHN.F {{not a typo|1890-13}}) found in the Callovian aged Marnes de Dives near Villers-sur-mer in the Calvados department of Normandy, France.<ref>Morel de Glasville M. 1876. Sur la cavité crânienne et la position du trou optique dans le ''Steneosaurus heberti''. Bulletin de la Société Géologique de France '''3'''(4):342-348</ref><ref>Brignon A. 2018. L'holotype de ''Steneosaurus heberti'' Morel de Glasville, 1876 : quelques précisions historiques sur une des plus remarquables découvertes paléontologiques faites aux Vaches Noires. L'Echo des Falaises, revue de l'Association paléontologique de Villers-sur-Mer, '''22''':7-22</ref><ref>Brignon A. 2018. La découverte du ''Steneosaurus heberti'' Morel de Glasville 1876 dans le Jurassique des Vaches Noires. Fossiles, revue française de Paléontologie, '''36''':40-46</ref> 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.<ref name="Teleosauroidea"/>

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.<ref name="Teleosauroidea"/>

==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.<ref name="Teleosauroidea"/>

{{Clade|{{clade |1=''Macrospondylus bollensis'' |2={{clade |1=''Clovesuurdameredeor stephani'' |2={{clade |1=''Charitomenosuchus leedsi'' |2={{clade |1=''Seldsienean megistorhynchus'' |2={{clade |1=''Deslongchampsina larteti'' |label2=Machimosaurinae |2={{clade |1={{clade |1=''Proexochokefalos hebertii'' |2=cf. ''Proexochokefalos bouchardi''}} |2={{clade |1=''Neosteneosaurus edwardsi'' |2=''Andrianavoay baroni'' |label3=Machimosaurini |3={{clade |1=''Lemmysuchus obtusidens'' |2=''Yvridiosuchus boutilieri'' |3={{clade |1=''Machimosaurus buffetauti'' |2={{clade |1=''Machimosaurus mosae'' |2={{clade |1=''Machimosaurus rex'' |2=''Machimosaurus hugii''}}}}}}}}}}}}}}}}}}}}}}|label1=Machimosauridae}}

==Ecology==

''Proexochokefalos'' possessed a mandible well adapted for handling large prey, featuring some of the largest muscle attachment sites among machimosaurids. Its tooth morphology is also intermediate between that of typical "longirostrine" species such as ''Charitomenosuchus'' and the more durophagous ''Machimosaurus''. These adaptations point to a shift towards feeding on larger prey items in ''Proexochokefalos'' and more derived machimosaurids. However it was not adapted for durophagy to the same extent as ''Machimosaurus'', instead being more of a generalist of large fish and marine reptiles.<ref name=eco>{{Cite journal|last1=Johnson|first1=M. M.|last2=Foffa|first2= D.|last3=Young|first3=M. T.|last4=Brusatte|first4=S. L.|year=2022|title=The ecological diversification and evolution of Teleosauroidea (Crocodylomorpha, Thalattosuchia), with insights into their mandibular biomechanics|journal=Ecology and Evolution|volume=12|issue=11 |article-number=e9484 |doi=10.1002/ece3.9484|doi-access=free|pmid=36415878 |bibcode=2022EcoEv..12E9484J |hdl=20.500.11820/07ef2706-2019-40ec-add6-6eb522f6f193|hdl-access=free|pmc=9674474}}</ref>

== References == {{reflist}}

Category:Thalattosuchia Category:Callovian life Category:Oxfordian life Category:Kimmeridgian life Category:Late Jurassic reptiles of Europe Category:Middle Jurassic reptiles of Europe Category:Jurassic France Category:Fossils of France Category:Jurassic Switzerland Category:Fossils of Switzerland Category:Fossil taxa described in 2020 Category:Prehistoric pseudosuchian genera