''Gorgonops'' (from el, Γοργών 'Gorgon' and 'eye, face', literally '

Gorgon A Gorgon ( /ˈɡɔːrɡən/; plural: Gorgons, Ancient Greek: Γοργών/Γοργώ ''Gorgṓn/Gorgṓ'') is a creature in Greek mythology. Gorgons occur in the earliest examples of Greek literature. While descriptions of Gorgons vary, the te ...

eye' or 'Gorgon face') is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

gorgonopsia Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, a ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

s, of which it is the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...

, having lived during the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

(

Wuchiapingian In the geologic timescale, the Wuchiapingian or Wujiapingian (from in the Liangshan area of Hanzhong, Shaanxi Province) is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian Epoch or Series. Th ...

), about 260–254 million years ago in what is now

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

. Despite its popularity, ''Gorgonops'' is a medium-sized gorgonopsian (about long maximum), regularly confused by the general public with the more massive ''

Inostrancevia ''Inostrancevia'' is an extinct genus of carnivorous therapsids, containing the largest members of gorgonopsians, predators characterized by long, saber-tooth-like canines. The various species inhabited European Russia during the Upper Tatar ...

'', known from

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

, due to their similar appearance and the various media that tend to refer them by the name of the group they belong rather than by their

genus name Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

s, which does not help in differentiation.

History of discovery

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

of the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

, ''Gorgonops torvus'', was in 1876 one of the first

s described, by Richard Owen, who also coined the name "Dinosauria" on the basis of the first known

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s. It was also used as the type for which

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...

described the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Gorgonopsidae in 1890. Five years later, in 1895,

Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fat ...

used this genus to establish the group as a whole, which he will name for the occasion Gorgonopsia. In later years, a large number of further

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

and genera were designated, but some of these turned out to be synonyms. Since the publication of the Sigogneau-Russell (1989), the dating of the Karoo Basin (

Beaufort Group The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underli ...

) has been revised. According to Smith and Keyser 1995, ''Gorgonops'' is known from the ''Tropidostoma'' and most of the ''Cistecephalus'' Assemblage Zones.

Description

''Gorgonops'' itself was a medium-sized representative of the group, with a skull length of 22 to 35 centimetres, depending on the species. It ranged from 1.2 to 2 metres long from nose to tail. ''Gorgonops'' would have been one of the key predators across southern Africa during the

, 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 ''Pareiasaurus'' is an extinct genus of pareiasauromorph reptile from the Permian period. It was a typical member of its family, the pareiasaurids, which take their name from this genus. Fossils have been found in the Beaufort Group. Descript ...

''. Aside from the teeth, one of the key predatory advantages that ''Gorgonops'' had over prey were that the legs supported the body from below rather than sprawling out to the sides like in most prey animals of the time. Aside from allowing for more energy efficient locomotion, the legs would have also allowed for a much faster pace. What animals were hunted however would depend upon the size of the individual ''Gorgonops'', and there were some quite broad differences between species in terms of size.

Skull

Relative to body size, ''Gorgonops'' had a deep skull which had a triangular profile when viewed from above. Perhaps the most distinctive features were two enlarged canine teeth that were so big ( 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)

The type species. The holotype is an incomplete and flattened skull found at Mildenhalls,

Fort Beaufort Fort Beaufort ( Xhosa: iBhofolo) is a town in the Amatole District of South Africa's Eastern Cape Province, and had a population of 25,668 in 2011. The town was established in 1837 and became a municipality in 1883. The town lies at the conflu ...

, 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.

''Gorgonops whaitsi'' (Broom, 1912)

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 A Reference Card or "Romer" is a device for increasing the accuracy when reading a grid reference from a map. Made from transparent plastic, paper or other materials, they are also found on most baseplate compasses. Essentially, it is a speciall ...

placed ''Gorgonops'' and ''Scymnognathus'' in two different families, while Sigogneau-Russell 1989 placed the two species in the same genus, and considers ''G. whaitsi'' a more primitive (less derived) form. Synonyms: ''Scymnognathus whaitsi'' (Broom, 1912)

''Gorgonops longifrons'' (Haughton 1915)

A large specimen known from an incomplete and flattened skull about 35 cm long.

Orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

larger and snout longer than ''G. whaitsi'', from which it may have descended.

Beaufort West Beaufort West (Afrikaans: ''Beaufort-Wes''; Xhosa: ''eBhofolo'') is a town in the Western Cape province in South Africa. It is the largest town in the arid Great Karoo region, and is known as the "Capital of the Karoo". It forms part of the Beau ...

, ''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

Stage). See Jacobs ''et al.'' 2005 for more on this species discussion on its age. Synonyms: ''Chiwetasaurus dixeyi'' (Haughton, 1926)

''Gorgonops? kaiseri'' (Broili & Schroeder, 1934)

A large (estimated total length about 35 cm long), incomplete skull, with a high snout and narrower in the rear than other species, from the "High ''Tapinocephalus'' zone" (i.e. earlier than the other species, most probably ''Pristerognathus'' Assemblage Zone) Synonyms: ''Pachyrhinos kaiseri'' (Broili & Schroeder, 1934)

Classification

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from the phylogenetic analysis of Gebauer (2007):

References

* Sigogneau-Russell, D., 1989, "Theriodontia I - Phthinosuchia, Biarmosuchia, Eotitanosuchia, Gorgonopsia" Part 17 B I, ''Encyclopedia of Paleoherpetology'', Gutsav Fischer Verlag, Stuttgart and New York * Jacobs, L. L., Winkler, D. A., Newman, K. D., Gomani, E. M. & Deino, A., 2005, Therapsids from the Permian Chiweta Beds and the age of the Karoo Supergroup in Malawi. '' Palaeontologia Electronica''. Vol. 8, #1, pp. 28A: 21-2
online
* Smith, R.H.M. and Keyser, A.W. 1995. Biostratigraphy of the Tropidostoma Assemblage Zone. Geological Survey of South Africa, South African Committee for Stratigraphy, Biostratigraphic Series, 1:18-22. {{Taxonbar, from=Q131690 Gorgonopsia Prehistoric therapsid genera Lopingian synapsids of Africa Fossil taxa described in 1876 Taxa named by Richard Owen Wuchiapingian genus first appearances Wuchiapingian genus extinctions