Gorgonopsia
Encyclopedia
Gorgonopsia is a suborder of therapsid synapsid
Synapsid
Synapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...

s. Their name is a reference to the Gorgon
Gorgon
In Greek mythology, the Gorgon was a terrifying female creature. The name derives from the Greek word gorgós, which means "dreadful." While descriptions of Gorgons vary across Greek literature, the term commonly refers to any of three sisters who had hair of living, venomous snakes, and a...

s of Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

. Like other therapsids, gorgonopsians were at one time called "mammal-like reptiles". Their mammalian specializations include differentiated (heterodont) tooth shape, a fully developed temporal fenestra, pillar-like rear legs, a vaulted palate that may have facilitated breathing while holding the prey, and incipiently developed ear bones . Gorgonopsians are a part of a group of therapsids called theriodont
Theriodont
Theriodonts , are a major group of therapsids. They can be defined in traditional, Linnaean terms, in which case they are a suborder of mammal-like reptiles that lived from the Middle Permian to the Middle Cretaceous, or in Cladistic terms, in which case they include not only the traditional...

s, which includes mammals .
They were among the largest carnivores of the late Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

. The largest known, Inostrancevia
Inostrancevia
Inostrancevia is a genus of gorgonopsid therapsid found in Sokolki, on the Smaller Northern Dvina River near Kotlas in Arkhangelsk Oblast, Russia. The animal lived 251 million years ago during the Late Permian. The species I...

, was the size of a large bear with a 45 cm long skull, and 12-cm long saber-like teeth (clearly an adaptation to being a carnivore). It is unknown whether they had fur
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...

, scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...

, or naked skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

.

Evolutionary history

Gorgonopsids (Gorgonopsia) are theriodont
Theriodont
Theriodonts , are a major group of therapsids. They can be defined in traditional, Linnaean terms, in which case they are a suborder of mammal-like reptiles that lived from the Middle Permian to the Middle Cretaceous, or in Cladistic terms, in which case they include not only the traditional...

s, a major group of therapsids that included the ancestors of mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s. Gorgonopsians evolved in the Middle Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

, from a reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

-like therapsid that also lived in that period. The early gorgonopsians were small, being no larger than a dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

. The extinction of dinocephalians (who dominated the Middle Permian world) led the gorgonopsians to be the dominant predators of the Late Permian. Some had approached the size of a rhinoceros
Rhinoceros
Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia....

, such as Inostrancevia
Inostrancevia
Inostrancevia is a genus of gorgonopsid therapsid found in Sokolki, on the Smaller Northern Dvina River near Kotlas in Arkhangelsk Oblast, Russia. The animal lived 251 million years ago during the Late Permian. The species I...

, the largest of the gorgonopsians. A nearly complete fossil of Rubidgea
Rubidgea
Rubidgea is an extinct genus of therapsid. It had very large canines, longer than the teeth of the dinosaur Tyrannosaurus rex. It lived in the Permian period. Rubidgea reached a length of and had a long skull....

 has been found in South Africa. The Gorgonopsia became extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally 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 recover may have been lost before this point...

 at the end of the Permian period
Permian-Triassic extinction event
The Permian–Triassic extinction event, informally known as the Great Dying, was an extinction event that occurred 252.28 Ma ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras...

, being the only theriodont line to be terminated by this mass extinction.

Classification

The gorgonopsians are one of the three groups of theriodonts (the other two were the therocephalia
Therocephalia
Therocephalians are an extinct suborder of carnivorous eutheriodont therapsids that lived from the middle and late Permian into the Triassic 265.0—245.0 Ma existing for approximately ....

ns, and the cynodont
Cynodont
Cynodontia or cynodonts are a taxon of therapsids which first appeared in the Late Permian and were eventually distributed throughout all seven continents by the Early Triassic . This clade includes modern mammals and their extinct close relatives. They were one of the most diverse groups of...

s). Theriodonts are related to the herbivorous Anomodontia. Gorgonopsia includes three subfamilies, the Gorgonopsinae, Rubidgeinae and Inostranceviinae, plus a larger number of genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 that have not been placed in any of these groups. A total of 25 genera and 41 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, with the genera described most completely being Dinogorgon
Dinogorgon
Dinogorgon was a gorgonopsid that lived in the Late Permian period of South Africa. Dinogorgon was a predator that ate reptiles and smaller therapsids. Its closest relatives included Lycaenops, and possibly Gorgonops. Like all other gorgonopsids, Dinogorgon perished prior to, or during the...

, Inostrancevia and Rubidgea
Rubidgea
Rubidgea is an extinct genus of therapsid. It had very large canines, longer than the teeth of the dinosaur Tyrannosaurus rex. It lived in the Permian period. Rubidgea reached a length of and had a long skull....

.

The most comprehensive review of the group is by Sigogneau-Russell, 1989. However, there has not been a detailed cladistic
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 assessment of the phylogeny of these animals.

  • Order Therapsida
    Therapsida
    Therapsida is a group of the most advanced synapsids, and include the ancestors of mammals. Many of the traits today seen as unique to mammals had their origin within early therapsids, including hair, lactation, and an erect posture. The earliest fossil attributed to Therapsida is believed to be...

  • SUBORDER GORGONOPSIA
    • Family Gorgonopsidae
      • Aelurognathus
        Aelurognathus
        Aelurognathus is an extinct genus of therapsid....

      • Aelurosaurus
        Aelurosaurus
        Aelurosaurus is an extinct genus of Gorgonopsia. It was first named by Owen in 1881, and contains four species, A. angusticeps, A. felinus, A. striatidens, and A. whaitsi.-Sources:*...

      • Aloposaurus
        Aloposaurus
        Aloposaurus is an extinct genus of Gorgonopsia. It was first named by Broom in 1910, and contains one species, A. gracilis.- Sources :*...

      • Arctognathus
        Arctognathus
        Arctognathus is an extinct genus of gorgonopsid that thrived during the Late Permian.A carnivore, like all gorgonopsid, Arctognathus was given its name in reference to its short and rounded snout. There are two recognized species: A. curvimola and A. breviceps; and two unrecognized species: A....

      • Arctops
        Arctops
        Arctops is an extinct genus of therapsid known from the Late Permian of South Africa. Its skull was 30 cm long. It perished during or before the P-T Extintion event....

      • Broomisaurus
        Broomisaurus
        Broomisaurus is an extinct genus of Gorgonopsia. It was first named by Broom in 1913, and contains two species, B. planiceps and B. rubidgei.-Sources:...

      • Cephalicustriodus
      • Cerdorhinus
        Cerdorhinus
        Cerdorhinus is an extinct genus of non-mammalian synapsid.-References:*...

      • Clelandina
        Clelandina
        Clelandina is an extinct genus of Gorgonopsia. It was first named by Broom in 1948, and contains four species, C. majora, C. maximus, C. rubidgei and C. scheepersi.-Sources:**-Further reading:...

      • Cyonosaurus
        Cyonosaurus
        Cyonosaurus is a genus of the extinct suborder Gorgonopsia. There are five species in this genera: C. broomianus, C. kitchingi, C. longiceps , C. rubidgei,, and C. tenuirostris. They lived in the late Permian period, with fossils discovered in South Africa...

      • Dinogorgon
        Dinogorgon
        Dinogorgon was a gorgonopsid that lived in the Late Permian period of South Africa. Dinogorgon was a predator that ate reptiles and smaller therapsids. Its closest relatives included Lycaenops, and possibly Gorgonops. Like all other gorgonopsids, Dinogorgon perished prior to, or during the...

      • Eoarctops
        Eoarctops
        Eoarctops is an extinct genus of Gorgonopsia. It was first named by Haughton in 1929, and contains one species, E. vanderbyli. The jaw of an Eoarctops shows four or five upper incisors, a canine, and three molars in the same margin.-Sources:**...

      • Galesuchus
        Galesuchus
        Galesuchus is an extinct genus of Gorgonopsia. Its fossils have been found in Africa, in the Middle-Permian rocks. Galesuchus had a small skull and a short snout.-Further reading:...

      • Leontocephalus
        Leontocephalus
        Leontocephalus is an extinct genus of Gorgonopsia. It was first named by Broom in 1940, and contains four species, L. cadlei, L. haughtoni, L. intactus, and L. rubidgi...

      • Lycaenops
        Lycaenops
        Lycaenops is a genus of carnivorous therapsid . It measured about 1 meter long and lived during the late mid-Permian to the early Late Permian in what is now South Africa....

      • Paragalerhinus
        Paragalerhinus
        Paragalerhinus is an extinct genus of Gorgonopsia. It was first named by Sigogneau in 1970, and contains one species, P. rubidgei.-Sources:**...

      • Scylacognathus
        Scylacognathus
        Scylacognathus is an extinct genus of Gorgonopsia. It was first named by Broom in 1913, and contains four species, S. grimbeeki, S. major, S. parvus, and S. robustus. The formula for its upper jaw is I5, CI, PC5.-Sources:**...

      • Sycosaurus
        Sycosaurus
        Sycosaurus is an extinct genus of Gorgonopsia. It was first named by Haughton in 1924, and contains four species, S. brodiei, S. kingoriensis, S. laticeps, S. vanderhorsti...

      • Viatkogorgon
        Viatkogorgon
        Viatkogorgon is an extinct genus of therapsid....

      • Subfamily Gorgonopsinae
        • Gorgonops
          Gorgonops
          Gorgonops is an extinct genus of therapsid which lived about 255-250 million years ago, during the latest part of the Permian Period. It was a typical representative of the suborder Gorgonopsia, the dominant predators of their day, which in the largest forms grew to over four metres long...

        • Sauroctonus
          Sauroctonus
          Sauroctonus was a large gorgonopsid that lived in the Late Permian epoch before the Permian-Triassic extinction event that wiped out many life forms on Earth...

        • Scylacops
          Scylacops
          Scylacops is an extinct genus of Gorgonopsia. It was first named by Broom in 1913, and contains two species, S. bigendens, and S. capensis. Its fossils have been found in South Africa. It is believed to be closely related to the Gorgonopsian Sauroctonus progressus. Scylacops was a moderately-sized...

      • Subfamily Inostranceviinae
        • Inostrancevia
          Inostrancevia
          Inostrancevia is a genus of gorgonopsid therapsid found in Sokolki, on the Smaller Northern Dvina River near Kotlas in Arkhangelsk Oblast, Russia. The animal lived 251 million years ago during the Late Permian. The species I...

        • Pravoslavleria
          Pravoslavleria
          Pravoslavlevia is a genus of the suborder Gorgonopsia.It lived in the late permian and is part of the Sokolki subcomplex of Russia.It had a skull 22 cm long.The animals total leingth was about 1,4 meters.Only one species is known....

      • Subfamily Rubidgeinae
        • Broomicephalus
          Broomicephalus
          Broomicephalus is an extinct genus of therapsid....

        • Niuksenitia
          Niuksenitia
          Niuksenitia is an extinct genus of gorgonopsid. It lived in the Permian period....

        • Prorubidgea
          Prorubidgea
          Prorubidgea is an extinct genus of Gorgonopsia. It was first named by Broom in 1940, and contains six species, P. alticeps, P. brinki, P. brodiei, P. maccabei, P. pugnax, and P. robusta. Its fossils have been found in South Africa. Prorubidgeas skull measured about 25.5 cm in length.-External...

        • Rubidgea
          Rubidgea
          Rubidgea is an extinct genus of therapsid. It had very large canines, longer than the teeth of the dinosaur Tyrannosaurus rex. It lived in the Permian period. Rubidgea reached a length of and had a long skull....

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