''Rubidgea'' is a genus of

gorgonopsid 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 ...

from the upper Permian of South Africa and Tanzania, containing the species ''Rubidgea atrox''. The generic name ''Rubidgea'' is sometimes believed to be derived from the surname of renowned

Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi-desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ext ...

paleontologist, Professor Bruce Rubidge, who has contributed to much of the research conducted on therapsids of the

Karoo Basin The Karoo Supergroup is the most widespread stratigraphy, stratigraphic unit in Africa south of the Kalahari Desert. The group (stratigraphy), supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Pennsylvan ...

. However, this generic name was actually erected in honor of Rubidge's paternal grandfather, Sydney Rubidge, who was a renowned fossil hunter. Its species name ''atrox'' is derived from Latin, meaning “fierce, savage, terrible”. ''Rubidgea'' is part of the gorgonopsian subfamily Rubidgeinae, a

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

group of large-bodied gorgonopsians restricted to the Late Permian ( Lopingian). The subfamily Rubidgeinae first appeared in the ''Tropidostoma'' Assemblage Zone. They reached their highest diversity in the '' Cistecephalus'' and ''

Daptocephalus ''Daptocephalus'' is an extinct genus of non- mammalian synapsid anomodont dicynodont, it which was found in Late Permian strata, in a biozone known precisely for the presence of fossils of this dicynodont, the ''Daptocephalus'' Zone, in the Ka ...

'' assemblage zones of 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 ...

in South Africa.

History of discovery

The first ''Rubidgea'' fossil was discovered by C. J. M. "Croonie" Kitching, the father of renowned paleontologist James Kitching, on the farm Doornberg outside the small town

Nieu-Bethesda Nieu-Bethesda (Afrikaans for ''New Bethesda'') is a village in the Eastern Cape at the foot of the Sneeuberge, approximately north of Graaff Reinet. It was founded in 1875 as a church town, like many other Karoo villages, and attained municipa ...

sometime in the 1930s. In a paper published in 1938, Robert Broom named the fossil ''Rubidgea kitchingi''. Broom noted the large size of the new

fossil, stating that it was a new species. Subsequent discoveries in the following decades confirmed Broom's suspicions that a new subfamily of gorgonopsians should be categorised, and the Rubidgeinae was erected.

Description

''Rubidgea'' was the largest African gorgonopsians and one of the largest gorgonopsians known to have lived. The largest specimens had skulls that measure up to in length. ''Rubidgea'' was a heavily-built, large-bodied apex predator, and sported a thick skull with long, sabre-like canines. The Rubidgeinae group as a whole were the largest gorgonopsians known to have lived, and are characterised by their robust skeletal features, particularly their skulls which are heavily- pachyostosed. The genus ''Rubidgea'' is composed of three species, ''R. atrox'', ''R. platyrhina'', and ''R. majora''.

Classification

The Rubidgeinae are a subfamily of

gorgonopsids that have only been found in Africa. They are composed of six

genera 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 ...

and 17 species. The Rubidgeinae are closely related to their sister group, the

Inostranceviinae Inostranceviinae is an extinct subfamily of gorgonopsid therapsids that lived during the Late Permian. Only two genera are known, both from Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning East ...

, which have only been found in Russia. Out of the gorgonopsian

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

, the

systematics Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic tre ...

of the Rubidgeinae is the best resolved due to their distinctive character traits. The

of other gorgonopsian subfamilies remain chaotic due to a high degree of

cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

homomorphism between taxa, making it difficult to distinguish different taxa effectively. The cladogram below (Kammerer and Rubidge 2022) displays the currently accepted

systematic Systematic may refer to: Science * Short for systematic error * Systematic fault * Systematic bias, errors that are not determined by chance but are introduced by an inaccuracy (involving either the observation or measurement process) inheren ...

relationships of the Gorgonopsia.

Correlation

Numerous therapsid species, including rubidgenae gorgonopsids, are used as biostratigraphic markers in other African Basins, such as the Upper Madumabisa Mudstone Formation of Zambia, and the Chiweta Beds of Malawi. ''Rubidgea'' fossils have been recovered from the

Usili Formation The Usili Formation is a Late Permian geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Permian, including temnospondyls, pareiasaurs, therapsids and the archosauromorph ''Aenigmastropheus''. History ...

of Tanzania, indicating biostratigraphic correlation with upper Permian-aged deposits in South Africa.Parrington, F. R. "A new genus of gorgonopsid from East Africa." Annals of the South African Museum 64 (1974): 47-52. No rubidgeinae fossils have been found outside of African deposits to date, although the

are considered to be their Russian counterparts.

References

{{Taxonbar, from=Q1977910 Gorgonopsia Prehistoric therapsid genera Permian synapsids of Africa Fossil taxa described in 1938