Regisaurus

{{short description|Genus of therapsids from the Early Triassic of South Africa}}

{{Taxobox

| name = Regisaurus

| fossil_range = {{Fossil range|Early Triassic}}

| image = Regisaurus skull.jpg

| image_width =

| image_caption = Skull cast seen from below, Museum of Evolution of Polish Academy of Sciences, Warsaw

| regnum = Animalia

| phylum = Chordata

| classis = Synapsida

| ordo = Therapsida

| subordo = Therocephalia

| familia = Regisauridae

| genus = Regisaurus

| subdivision_ranks = Species

| subdivision =

R. jacobi Mendrez, 1972

}}

Regisaurus ("Rex's lizard", named after Francis Rex Parrington) is an extinct genus of small carnivorous therocephalian. It is known from a single described species, the type species Regisaurus jacobi, from the Early Triassic Lystrosaurus Assemblage Zone of South Africa, although at least one undescribed species is also known.{{cite book|author=C. H. Mendrez|year= 1972|chapter= On the skull of Regisaurus jacobi, a new genus and species of Bauriamorpha Watson and Romer 1956 (=Scaloposauria Boonstra 1953), from the Lystrosaurus-zone of South Africa|title= Studies in Vertebrate Evolution|editor1=K. A. Joysey |editor2=T. S. Kemp |pages= 191–212|publisher=Oliver & Boyd|location=Edinburgh|isbn= 9780050021316}}

Description

File:Regisaurus1DB.jpg

It was a rather derived baurioid, with a robust skull, short tail, long limbs and relatively large canines. It was apparently related to Urumchia and like Urumchia, it had vomer bones, which form the secondary palate, but they do not narrow to a tip like in Urumchia. However, it retained some primitive characteristics. It had six incisor teeth in each side of the jaw, whereas other baurioids had less.{{Cite web| title=The postcranial skeletal anatomy of the therocephalian Regisaurus (Therapsida: Regisauridae) and its utilization for biostratigraphic correlation | url=http://wiredspace.wits.ac.za/bitstream/handle/10539/16101/2007.v.42.Fourie_%26_Rubidge_Postcranial_anatomy_therocephalian.pdf?sequence=1 | archive-url=https://web.archive.org/web/20160305084841/http://wiredspace.wits.ac.za/bitstream/handle/10539/16101/2007.v.42.Fourie_&_Rubidge_Postcranial_anatomy_therocephalian.pdf?sequence=1 | archive-date=2016-03-05}} It was probably carnivorous, and ate insects and small vertebrates

Discovery and species

Regisaurus was discovered in 1964 by James W. Kitching and it was named in 1972 by C. H. Mendrez. Two species are known, the type species Regisaurus jacobi and an additional undescribed species. R. jacobi is known from the holotype FRP 1964/27 and the referred specimen BP/1/3973,{{Cite web|url=http://www.paleofile.com/Theriodontia/Regisaurus.asp|title = Untitled Document}} while the undescribed species is known only from the Holotype T837.{{cite journal |last=Kemp |first=T. S. |year=1986 |title=The skeleton of a baurioid therocephalian therapsid from the Lower Triassic (Lystrosaurus Zone) of South Africa |journal=Journal of Vertebrate Paleontology |volume=6 |issue=3 |pages=215–232 |doi=10.1080/02724634.1986.10011617 |jstor=4523096 |url=http://users.ox.ac.uk/~tskemp/pdfs/BaurioidJVP1986.pdf |access-date=26 March 2011 |archive-date=4 October 2012 |archive-url=https://web.archive.org/web/20121004044031/http://users.ox.ac.uk/~tskemp/pdfs/BaurioidJVP1986.pdf |url-status=dead }}{{Cite web|url=http://www.paleofile.com/Theriodontia/Regisaurussp.asp|title=Untitled Document}}

Classification

Below is a cladogram modified from Sidor (2001) and Huttenlocker (2009):{{cite journal |last=Sidor |first=C.A. |year=2001 |url=https://www11.cac.washington.edu/burkemuseum/collections/paleontology/sidor/Sidor2001.pdf |title=Simplification as a trend in synapsid cranial evolution |journal=Evolution |volume=55 |issue=7 |pages=1419–1442 |pmid=11525465 |doi=10.1554/0014-3820(2001)055[1419:saatis]2.0.co;2}}{{cite journal |last=Huttenlocker |first=A. |year=2009 |title=An investigation into the cladistic relationships and monophyly of therocephalian therapsids (Amniota: Synapsida) |journal=Zoological Journal of the Linnean Society |volume=157 |issue=4 |pages=865–891 |doi=10.1111/j.1096-3642.2009.00538.x|doi-access=free }}

{{clade| style=font-size:85%;line-height:85%

|label1=Baurioidea

|1={{clade

|1=Ictidosuchops rubidgei

|label2=Ictidosuchidae

|2={{clade

|1=Ictidosuchus primaevus

|2=Ictidosuchoides longiceps}}

|3={{clade

|label1=Regisauridae

|1={{clade

|1=Regisaurus jacobi