Rubidgeinae is an extinct subfamily 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 ...

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 only from

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. They were among the largest gorgonopsians, and their fossils are common in the

Cistecephalus ''Cistecephalus'' is an extinct genus of dicynodont therapsid from the Late Permian of southern Africa (South Africa and Zambia). It was a small, specialised, burrowing dicynodont, possibly with habits similar to a modern mole. The head was flat ...

and Daptocephalus assemblage zones 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 ...

. They 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, ...

, and became extinct at the end of the Permian.

Description

Rubidgeines were large, quadrupedal carnivores of the family

Gorgonopsidae 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, ...

. Their largest teeth are their upper

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

, which were blade-like and had well-developed serrations. Their postcanine teeth were small and conical, but were also frequently serrated. Tooth replacement was rapid relative to basal therocephalians. Rubidgeines can be distinguished from other gorgonopsians by the absence of a blade-like parasphenoid bone and reduced or absent preparietal bone. The jugal bone, while narrow in most gorgonopsians, was often broadly expanded in rubidgeines. The largest rubidgeins were ''

Dinogorgon ''Dinogorgon'' is a genus of gorgonopsid from the Late Permian of South Africa and Tanzania. The generic name ''Dinogorgon'' is derived from Greek, meaning "terrible gorgon", while its species name ''rubidgei'' is taken from the surname of renown ...

'' and ''

Rubidgea ''Rubidgea'' is a genus of gorgonopsid 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 paleontolo ...

''.

Paleobiology

Rubidgeines were among the largest gorgonopsians known, and the largest known from

. They were also the largest predators in their environment. Their massive canines and serrated teeth indicate that they were adapted for macropredation. The robust skull roof and supraorbital bosses of rubidgeines likely acted to protect the skull from the stress inflicted during prey capture, and similar morphology has been seen in many other macropredators in the fossil record, including

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

dinosaurs 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 ...

. The presence of this skull morphology is one of multiple adaptations seen in predators that utilize the skull, rather than the limbs, in prey capture.

Classification and systematics

Below is a cladogram by Kammerer in 2016.

References

{{Taxonbar, from=Q21293518 Gorgonopsia Permian extinctions Prehistoric animal subfamilies Tetrapod subfamilies