{{Short description|Extinct genus of reptiles}} {{Italic title}} {{Taxobox | name = ''Polysphenodon'' | fossil_range = Late Triassic, {{fossil_range|235|205}} | image = Polysphenodon skull.svg | image_caption = Reconstructed skull | regnum = Animalia | phylum = Chordata | classis = Reptilia | ordo = Sphenodontia | familia = | subfamilia = | genus = {{extinct}}'''''Polysphenodon''''' | genus_authority = Jaeckel, 1911 | type_species = {{extinct}}'''''Polysphenodon mulleri''''' | type_species_authority = Jaeckel, 1911 }}
'''''Polysphenodon''''' is an extinct genus of sphenodontian reptile with a single species '''''Polysphenodon mulleri''''' from the Late Triassic Keuper Group of Germany.<ref name=Fraser1989>N. C. Fraser and M. J. Benton. (1989) The Triassic reptiles ''Brachyrhinodon'' and ''Polysphenodon'' and the relationships of the sphenodontids. ''Zoological Journal of the Linnean Society'' 96:413-445</ref>
== History of discovery == The genus and only known species ''Polysphenodon mulleri'' was described by Otto Jaekel in 1911''.<ref name="Jaekel1911">Jaekel, O (1911) Die Wierbeltiere. Eine Übersicht über diefossilen und lebenden Formen. ''Borntraeger, Berlin'', 252p</ref> Polysphenodon mulleri'' is known from a single partial skeleton recovered from a borehole sample at {{convert|775|m|ft}} depth, which includes parts of the skull, limbs and tail vertebrae.<ref name="Jaekel1911" /> This specimen has been lost since the 1930s, but is known from several casts.<ref name="Fraser1989" />
==Description==
The skull was around {{Convert|2.5|cm|in}} long in life. The snout is relatively short, even when accounting for post-mortem distortion. The limbs of ''Polysphenodon'', particularly the tibia, are long relative to the size of the skull and are similar in proportions to some species of ''Homoeosaurus''. This resemblance is considered to be indicative of similar locomotory requirements rather than close evolutionary relationships.<ref name="Fraser1989" /> ==Taxonomy==
Recent studies have placed ''Polysphenodon'' as a member of Eusphenodontia.<ref name=":0">{{Cite journal |last1=Romo de Vivar |first1=Paulo R. |last2=Martinelli |first2=Agustín G. |last3=Schmaltz Hsiou |first3=Annie |last4=Soares |first4=Marina Bento |date=2020-07-02 |title=A New Rhynchocephalian from the Late Triassic of Southern Brazil Enhances Eusphenodontian Diversity |url=https://www.tandfonline.com/doi/full/10.1080/14772019.2020.1732488 |journal=Journal of Systematic Palaeontology |language=en |volume=18 |issue=13 |pages=1103–1126 |doi=10.1080/14772019.2020.1732488 |bibcode=2020JSPal..18.1103R |issn=1477-2019|url-access=subscription }}</ref> Some authors have placed ''Polysphenodon'' as part of the family Clevosauridae alongside ''Clevosaurus'' and ''Brachyrhinodon'',<ref>{{Cite journal |last1=Hsiou |first1=Annie Schmaltz |last2=De França |first2=Marco Aurélio Gallo |last3=Ferigolo |first3=Jorge |date=2015-09-10 |editor-last=Beatty |editor-first=Brian Lee |title=New Data on the Clevosaurus (Sphenodontia: Clevosauridae) from the Upper Triassic of Southern Brazil |journal=PLOS ONE |language=en |volume=10 |issue=9 |article-number=e0137523 |doi=10.1371/journal.pone.0137523 |doi-access=free |issn=1932-6203 |pmc=4565693 |pmid=26355294|bibcode=2015PLoSO..1037523H }}</ref> though other studies have recovered ''Polysphenodon'' as unrelated to these taxa''.''<ref name=":0" />
Cladogram following Sues and Schoch, 2023:<ref>{{Cite journal |last1=Sues |first1=Hans-Dieter |last2=Schoch |first2=Rainer R. |date=2023-11-07 |title=The oldest known rhynchocephalian reptile from the Middle Triassic (Ladinian) of Germany and its phylogenetic position among Lepidosauromorpha |url=https://anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25339 |journal=The Anatomical Record |volume=307 |issue=4 |pages=776–790 |language=en |doi=10.1002/ar.25339 |issn=1932-8486 |pmid=37937325 |s2cid=265050255|url-access=subscription }}</ref>{{clade|{{clade |label1=Rhynchocephalia |1={{clade |1=''Wirtembergia hauboldae'' |2={{clade |1=''Gephyrosaurus bridensis'' |label2=Sphenodontia |2={{clade |1=''Diphydontosaurus avonis'' |label2=Acrosphenodontia |2={{clade |1=''Planocephalosaurus robinsonae'' |2={{clade |1=''Rebbanasaurus jaini'' |2={{clade |1={{clade |1=''Godavarisaurus lateefi'' |2=''Theretairus antiquus''}} |label2=Eusphenodontia |2={{clade |1=''Polysphenodon mulleri'' |2={{clade |1=''Opisthiamimus gregori'' |2={{clade |label1=Clevosauridae |1={{clade |1={{clade |1=''Clevosaurus convallis'' |2={{clade |1=''Clevosaurus brasiliensis'' |2=''Clevosaurus hadroprodon''}}}} |2={{clade |1=''Clevosaurus bairdi'' |2={{clade |1=''Clevosaurus hudsoni'' |2=''Clevosaurus cambrica''}}}}}} |2=Neosphenodontia }}}}}}}}}}}}}}}}}}}}}}
==References== <references />
{{Sphenodontia}} {{Taxonbar|from=Q11823024}} Category:Triassic reptiles of Europe Category:Triassic lepidosaurs Category:Rhynchocephalia Category:Middle Triassic first appearances Category:Late Triassic extinctions Category:Prehistoric reptile genera
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