Anisodontosaurus

{{Short description|Extinct genus of reptiles}} {{Speciesbox | fossil_range = Middle Triassic, <br /> {{fossilrange|247.2|242.0}} | image = Anisodontosaurus greeri.jpg | image_caption = Holotype jaw | parent_authority = Welles, 1947 | taxon = Anisodontosaurus greeri | authority = Welles, 1947 }}

'''''Anisodontosaurus''''' is an extinct genus of trilophosaurid allokotosaur known from the Middle Triassic Moenkopi Formation of Arizona.<ref name=Welles1947/> The type species, '''''A. greeri''''', was named and described by Samuel Paul Welles in 1947.<ref name=Welles1947>S. P. Welles. (1947). Vertebrates from the Upper Moenkopi Formation of northern Arizona. ''University of California Publications in Geological Sciences'' 27(7):241-294</ref>

==Discovery and naming== The holotype, a jaw catalogued as UCMP V3922, was discovered in 1940 and was described seven years later.<ref name=Welles1947 />

Apart from the type specimen, ''Anisodontosaurus'' is known from the referred specimen UCMP 37815, a right ilium.<ref>R. L. Carroll. (1988). ''Vertebrate Paleontology and Evolution.'' 1-698</ref><ref>S. J. Nesbitt. 2005. The Moenkopi Formation along the Little Colorado River in eastern Arizona. In S. J. Nesbitt, W. G. Parker, R. B. Irmis (eds.), ''Guidebook to the Triassic Formations of the Colorado Plateau in northern Arizona, Mesa Southwest Museum Bulletin'' 9:13-23</ref>

==Classification== Its taxonomic placement was largely unknown (it was placed within the Eosuchia by Welles in 1947)<ref name=Welles1947 /> until the holotype was reassessed in 1998, when it was recovered as a lepidosauromorph or a trilophosaurid.<ref>A. P. Hunt, S. G. Lucas, and P. S. Spencer. (1998). A reassessment of the taxonomic affinities of the enigmatic tetrapod ''Anisodontosaurus greeri'' Welles 1947 from the Middle Triassic of western North America. ''Neues Jahrbuch für Geologie und Paläontologie - Monatshefte'' 1998(4):212-222</ref>

A 2023 redescription of available fossils supported its identification as a trilophosaurid, specifically as the sister taxon to ''Variodens'', from the Late Triassic of the United Kingdom. The clade containing ''Anisodontosaurus'' and ''Variodens'' is the longest-lasting subset of Trilophosauridae, as ''Anisodontosaurus'' is one of the oldest known members of the family while ''Variodens'' is among the youngest.<ref>{{Cite journal |last1=Foffa |first1=Davide |last2=Nesbitt |first2=Sterling J. |last3=Kligman |first3=Ben T. |last4=Butler |first4=Richard J. |last5=Stocker |first5=Michelle R. |date=2023-07-24 |title=New specimen and redescription of Anisodontosaurus greeri (Moenkopi Formation: Middle Triassic) and the spatiotemporal origins of Trilophosauridae |journal=Journal of Vertebrate Paleontology |language=en |doi=10.1080/02724634.2023.2220015 |issn=0272-4634|doi-access=free }}</ref>

== References == {{reflist}}

Category:Middle Triassic reptiles of North America Category:Trilophosauridae Category:Prehistoric reptile genera