''Eriphostoma'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 known from the

Middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...

(middle

Capitanian In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between and million years ago. It was preceded by th ...

stage) of ''Tapinocephalus'' Assemblage Zone,

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

. It has one known species, ''Eriphostoma microdon'', and was first named by

Robert Broom Robert Broom FRS FRSE (30 November 1866 6 April 1951) was a British- South African doctor and palaeontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow. From 1903 to 1910, he ...

1911 A notable ongoing event was the Comparison of the Amundsen and Scott Expeditions, race for the South Pole. Events January * January 1 – A decade after federation, the Northern Territory and the Australian Capital Territory ...

. It is the oldest known gorgonopsian and among the smallest and most basal members of the clade.

Description

Gorgonopsians were a morphologically conservative group, and like all gorgonopsians, ''Eriphostoma'' would have been a quadrupedal predator. It was among the smaller members of the group, with a skull less than long. It had a relatively short, deep snout and large orbits compared to other gorgonopsians. Like all gorgonopsians, it had five incisors and a canine tooth on each side of the upper jaw, but it had only three small postcanine teeth in its maxilla. The palate of ''Eriphostoma'' has delta-shaped palatine bosses covered in numerous teeth, like ''

Gorgonops ''Gorgonops'' (from el, Γοργών 'Gorgon' and 'eye, face', literally 'Gorgon eye' or 'Gorgon face') is an extinct genus of gorgonopsian therapsids, of which it is the type genus, having lived during the Late Permian (Wuchiapingian), about ...

'' and many basal therapsids, but not more derived gorgonopsians which tend to have ridge-like palatine bosses with few teeth.

History

''Eriphostoma'' was named in 1911 by

, based on a poorly preserved specimen collected by the Reverend J. H. Whaits in the town of Fraserburg Road (now

Leeu-Gamka Leeu-Gamka is a small town in the Western Cape province of South Africa, located north-east of Cape Town in the Karoo. History The town of Leeu-Gamka owes its existence to the route chosen by Prime Minister John Molteno for the Cape Government Ra ...

. The holotype was accessioned in the

American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...

with the specimen number AMNH FARB 5524. It was the first named gorgonopsian from the ''Tapinocephalus'' Assemblage Zone of the Beaufort Group. Despite its status as one of the oldest known gorgonopsians, its poor preservation meant that the specimen was largely ignored for the rest of the 20th century, and typically regarded as a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

''. A 1989 comprehensive revision of gorgonopsians only briefly mentioned it as an indeterminate

theriodont The theriodonts (clade Theriodontia) are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts. Naming In 1876, Rich ...

. However, in 2014, CT scanning of the holotype allowed its redescription as a valid species of gorgonopsian. Further study, and the discovery of new specimens, allowed most gorgonopsians from the ''Tapinocephalus'' AZ to be synonymized. The species ''Eriphostoma microdon'', ''Scylacognathus parvus'', ''Galesuchus gracilis'', and ''Eoarctops vanderbyli'' were synonymized, and ''Eriphostoma microdon'' became the valid name due to the

Principle of Priority 270px, '' valid name. Priority is a fundamental principle of modern botanical nomenclature and zoological nomenclature. Essentially, it is the principle of recognising the first valid application of a name to a plant or animal. There are two asp ...

. A fifth species of ''Tapinocephalus'' AZ gorgonopsian, ''Broomisaurus planiceps'', is probably also synonymous, but it is currently a ''nomen dubium'' due to its poor state of preparation.

Classification

''Eriphostoma'' is the most basal member of an endemic African radiation of gorgonopsians.

Provenance

All known specimens of ''Eriphostoma'' are from the

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 underlie ...

of South Africa. The holotype is from the

Abrahamskraal Formation The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a ma ...

, but some of the referred specimens are from the overlying Teekloof Formation. Biostratigraphically, it ranges from the upper ''Tapinocephalus'' Assemblage Zone to the upper ''Pristerognathus'' Assemblage Zone, and is the oldest known gorgonopsian.

References

{{Taxonbar, from=Q5389521 Gorgonopsia Prehistoric therapsid genera Guadalupian synapsids Guadalupian synapsids of Africa Taxa named by Robert Broom Capitanian genus first appearances Capitanian genus extinctions Fossil taxa described in 1911