Gorgonops

{{Short description|Extinct genus of therapsids}} {{More footnotes|date=September 2022}} {{Automatic taxobox | fossil_range = Lopingian (Wuchiapingian), {{fossil range|260|254}} | image = Gorgonops.jpg | image_caption = ''G. whaitsi'' skull (specimen 5537) | taxon = Gorgonops | authority = Owen, 1876 | type_species = {{extinct}}'''''Gorgonops torvus''''' | type_species_authority = Owen, 1876 | subdivision_ranks = Species | subdivision = * {{extinct}}'''''G. torvus''''' Owen, 1876 * {{extinct}}'''''G. whaitsi''''' Broom, 1912 * {{extinct}}'''''G. longifrons''''' Haughton, 1915 }}

'''''Gorgonops''''' (from {{langx|el|Γοργών}} 'Gorgon' and {{lang|el|ὤψ}} 'eye, face', literally 'Gorgon eye' or 'Gorgon face') is an extinct genus of gorgonopsian therapsid, of which it is the type genus. ''Gorgonops'' lived during the Late Permian (Wuchiapingian), about 260–254 million years ago in what is now South Africa.

==History of discovery== The holotype of the type species, ''Gorgonops torvus'', was one of the first therapsids discovered. It was described by Richard Owen, who also coined the name "Dinosauria" on the basis of the first known dinosaur fossils.<ref name=Owen1876>{{cite book|first=R.|last=Owen|author-link=Richard Owen|year=1876|title=Descriptive and illustrated catalogue of the fossil Reptilia of South Africa in the collection of the British museum|publisher=British Museum (Natural History)|pages=27–29|url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015009238919&view=1up&seq=43}}</ref> ''G. torvus'' was also used as the type for the family Gorgonopsidae, which was described by Richard Lydekker in 1890.<ref>{{cite book|first=R.|last=Lydekker|author-link=Richard Lydekker|year=1890|title=Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural history) Part IV|publisher=British Museum (Natural History)|page=111|url=https://www.biodiversitylibrary.org/item/125712#page/141/mode/1up}}</ref> Five years later, in 1895, Harry Govier Seeley used this genus to establish the larger clade of Gorgonopsia.<ref>{{cite journal|first=H. G.|last=Seeley|author-link=Harry Seeley|year=1895|title=Researches on the structure, organization, and classification of the fossil reptilia.—Part IX. section 1. On the Therosuchia|journal=Annals and Magazine of Natural History |volume=13 |issue=6 |page=375 |doi=10.1080/00222939408677718 |url=https://zenodo.org/record/2292163}}</ref> In later years, a large number of further species and genera were designated, though many of these were later determined to be synonyms.

''Gorgonops'' is known from the ''Tropidostoma'' and most of the ''Cistecephalus'' Assemblage Zones.<ref>{{Cite journal |last=Smith |first=R.H.M. |last2=Keyser |first2=A.W. |date=1995 |title=Biostratigraphy of the Tropidostoma Assemblage Zone |journal=Geological Survey of South Africa |volume=1 |pages=18–22}}</ref>

==Description== thumb|left|200 px|Restoration of ''G. whaitsi'' ''Gorgonops'' was a medium-sized gorgonopsian, with a skull length of {{Convert|22-35|cm|in}}, depending on the species. They ranged from {{Convert|1.2-2|m|ft}} long from nose to tail. ''Gorgonops'' would have been one of the key predators across southern Africa during the Late Permian. Because the canines were so large, they would have had little trouble in penetrating the tough hides of some of the herbivores of the time, particularly pareiasaurs such as ''Pareiasaurus''. Aside from the teeth, one of the key predatory advantages that ''Gorgonops'' had over prey was its semi-erect gait, compared to the sprawling gait exhibited by most prey animals of the time. Aside from allowing for more energy efficient locomotion, this allowed ''Gorgonops'' to travel at relatively high speeds.

===Skull=== thumb|''Gorgonops'' compared to a human. Relative to body size, ''Gorgonops'' had a deep skull with a triangular profile when viewed from above. Perhaps the most distinctive features were two enlarged canine teeth that were so big ({{convert|12|cm|in}} long) they almost protruded beyond the lower jaw. To help protect these teeth, the lower jaws grew in such a shape so that the anterior (front) portion was thicker than the posterior (rear) portion. This form would have protected the enlarged canine teeth from accidental damage, and was similar in bone function to the flanges of bone of sabre-toothed cats in the Cenozoic.

=== Species === ==== ''Gorgonops torvus'' (Owen, 1876) ==== thumb|right|''G. torvus'' The type species. The holotype is an incomplete and flattened skull, allegedly found at Mildenhall's farm (Xlu Xlu), on the Queen's Road south of Fort Beaufort, in the Eastern Cape of South Africa. A number of other specimens have been found since, all from the ''Tropidostoma'' and/or ''Cistecephalus'' Assemblage Zone(s). This was a medium-sized therapsid, with a skull about 22 cm in length. It is distinguished from other species by a longer snout, and other details of the bones of the skull. Originally considered rather simple, it is actually (according to Sigogneau-Russell) a rather specialised member of the group.<ref name=":0">{{Cite book |last=Sigogneau-Russell |first=D. |url=https://pfeil-verlag.de/en/publications/handbuch-der-palaeoherpetologie-encyclopedia-of-paleoherpetology-part-17b1-theriodontia-i/ |title=Encyclopedia of Paleoherpetology |publisher=Gustav-Fischer-Verlag |year=1989 |isbn=978-3-89937-033-1 |editor-last=H.-D. |editor-first=Sues |chapter=Theriodontia I}}</ref>

==== ''Gorgonops whaitsi'' (Broom, 1912) ==== thumb|170 px|right|Head of ''G. whaitsi'' Larger than ''G. torvus'', with the rear of the skull wider, and other details of proportion. Originally the type species of ''Scymnognathus''. Despite being known from a large number of specimens from the Karoo Basin, Beaufort West (''Tropidostoma''/''Cistecephalus'' Assemblage Zone), the species remains poorly known. Watson and Romer placed ''Gorgonops'' and ''Scymnognathus'' in two different families, while Sigogneau-Russell placed the two species in the same genus, and considers ''G. whaitsi'' a more primitive (less derived) form.<ref name=":0" /> Synonyms: ''Scymnognathus whaitsi'' (Broom, 1912)

==== ''Gorgonops longifrons'' (Haughton, 1915) ==== A large specimen known from an incomplete and flattened skull about {{Convert|35|cm|in}} long. Orbit larger and snout longer than ''G. whaitsi'', from which it may have descended. Beaufort West, ''Tropidostoma''/''Cistecephalus'' Assemblage Zone. Synonyms: ''Gorgonognathus longifrons'' (Haughton, 1915)

==== ''Gorgonops? eupachygnathus'' (Watson, 1921) ==== A flattened, incomplete, medium-sized skull, probably a juvenile of either ''G. torvus'' or ''G. whaitsi'' Synonyms: ''Leptotrachelus eupachygnathus'' (Watson, 1921); ''Leptotracheliscops eupachygnathus'' (Watson, 1921)

==== ''Gorgonops? dixeyi'' (Haughton, 1926) ==== A large, incomplete and flattened skull, from Chiweta Beds, Nyassaland. Placement uncertain. Probably Low ''Cistecephalus'' Assemblage Zone equivalent (= middle of the Wuchiapingian Stage).<ref>{{Cite journal |last=Jacobs |first=L.L. |last2=Winkler |first2=D.A. |last3=Newman |first3=K.D. |last4=Gomani |first4=E.M. |last5=Deino |first5=A. |date=2005 |title=Therapsids from the Permian Chiweta Beds and the age of the Karoo Supergroup in Malawi |url=http://palaeo-electronica.org/2005_1/jacobs28/issue1_05.htm |journal=Palaeontologia Electronica |volume=8 |issue=1 |pages=28A}}</ref> Synonyms: ''Chiwetasaurus dixeyi'' (Haughton, 1926)

==== ''Gorgonops? kaiseri'' (Broili & Schroeder, 1934) ==== A large (about {{Convert|35|cm|in}} long), incomplete skull, with a high snout and narrower in the rear than other species, from the "High ''Tapinocephalus'' zone" (earlier than the other species, most probably ''Pristerognathus'' Assemblage Zone) Synonyms: ''Pachyrhinos kaiseri'' (Broili & Schroeder, 1934)

==Classification== Below is a cladogram from Gebauer's 2007 phylogenetic analysis.<ref name=GEVI07>{{Cite thesis |degree=Ph.D. |title=Phylogeny and evolution of the Gorgonopsia with a special reference to the skull and skeleton of GPIT/RE/7113 ('''Aelurognathus?' parringtoni'') |url=http://tobias-lib.uni-tuebingen.de/volltexte/2007/2935/pdf/Eva_Gebauer.pdf |last=Gebauer |first=E.V.I. |year=2007 |publisher=Eberhard-Karls Universität Tübingen |location=Tübingen |pages=1–316 |archive-date=2012-07-22 |access-date=2014-07-13 |archive-url=https://web.archive.org/web/20120722014133/http://tobias-lib.uni-tuebingen.de/volltexte/2007/2935/pdf/Eva_Gebauer.pdf |url-status=dead }}</ref>

{{clade| style=font-size:100%;line-height:85% |label1=Gorgonopsia |1={{clade |1=''Aloposaurus'' |2={{clade |1=''Cyonosaurus'' |2={{clade |1=''Aelurosaurus'' |label2=Gorgonopsidae |2={{clade |1=''Scylacognathus'' |2={{clade |1=''Eoarctops'' |2='''''Gorgonops''''' |3={{clade |1=''Njalila'' |2={{clade |1=''Lycaenops'' |2={{clade |1=''Arctognathus'' |2={{clade |1=''Inostrancevia'' |label2=Rubidgeinae |2={{clade |1=''Aelurognathus'' |2={{clade |1=''Rubidgea'' |2={{clade |1=''Sycosaurus'' |2=''Clelandina'' }} }} }} }} }} }} }} }} }} }} }} }} }}

==See also== {{Portal|Paleontology}} * List of therapsids

==References== {{Commons category|Gorgonops}} {{Reflist}}

Category:Gorgonopsia Category:Prehistoric therapsid genera Category:Lopingian synapsids of Africa Category:Fossil taxa described in 1876 Category:Taxa named by Richard Owen Category:Wuchiapingian genus first appearances Category:Wuchiapingian genus extinctions