Brithopodidae

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iBrithopodidae
Fossil range: Wordian to Capitanian

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Class:	Synapsida
Order:	Therapsida
Suborder:	Dinocephalia
Superfamily:	Anteosauroidea
Family:	Brithopodidae

Genera

See under "included genera"

Brithopodidae are a paraphyletic family of primitive mostly carnivorous Dinocephalians known from the Middle Permian of Russia. Nowadays the name is used less often, being replaced by Anteosauria (a generic name for the clade that includes the carnivorous branch of dinocephalia (Hopson & Barghusen 1986, Rubidge & Sidor 2001).

The original Dinosaurus, named by Johann Fischer von Waldheim in 1845, was probably a specimen of the genus Brithopus.

1 Characteristics
2 Taxonomic history
3 Included genera
4 References
5 Links

[edit] Characteristics

The Brithopodids are very primitive Eutheraspids, not far removed from ancestral synapsids. The Russian paleontologist Peter Chudinov noted that the Ocher brithopidids are similar to but slightly more advanced then the contemporary or slightly later Phthinosuchidae and Eotitanosuchidae (Biarmosuchus and Eotitanosuchus) ( Chudinov, 1965 p.120). The skull of some Brithopodids closely resemble those of the early Biarmosuchia. The South African paleontologist Lieuwe Dirk Boonstra pointed out the great similarity between the skull of Syodon and that of Eotitanosuchus (Boonstra 1963 p.199).

Although the limbs are more upright, the postcranial skeleton retains the general form of the sphenacodont pelycosaurs. (Carroll 1988 p.371).

However, the temporal opening is greatly enlarged, indicated more space for jaw muscles and hence a much stronger bite. There are also sharp crests near the midline of the skull for attachment of jaw muscles. The canines are long, with cheek teeth adapted to piercing, and the incisors are also large and pointed, and intermesh when closed all of which indicates a carnivorous diet, and teeth adapted to cutting flesh from their prey (Carroll ibid).

[edit] Taxonomic history

The family was erected by Efremov in 1954 to include a number of large carnivorous therapsids found in the Copper Sandstones and other Cis-Uralian localities, including the Cis-Uralian Deinocephalian Complexes and the Isheevian Deinocephalian Complex (Olsen 1962 p.57).

Olsen included the Brithopodidae with the Phthinosuchidae and Biarmosuchidae in the larger category "Eotheriodontia". He did not consider the Brithopodids related to herbivorous Dinocephalia (Tapinocephalia) but saw them as related to the Gorgonopsia and other Theriodonts. His theory is not longer followed by current workers in this field.

Boonstra retained most of the Russian genera (along with Deuterosaurus) in the Brithopodidae, but transferred several genera to the Anteosauridae, the family based on Anteosaurus, which he erected at the same time. However he considered the two groups closely related, the Brithopodidae differing from the Anteosauridae by being somewhat more primitive.

Hopson and Barghusen, in the first cladistic study of the Therapsida, coined the term Anteosauria, and synonymised the families Brithopodidae and Anteosauridae. Their "Anteosaurini" is probably equivalent to Boonstra's "Anteosauridae", in that both include Anteosaurus and Doliosaurus/Doliosauriscus. (see Hopson & Barghusen 1986 p.91 and Boonstra 1969 pp,59-60)

King 1988 downgraded the Brithopodids to subfamily status (Brithopodinae).

In 1994, Ivakhnenko transferred several Brithopodid genera to the family Syodontidae.

[edit] Included genera

The following genera have been or are included in the family:

Admetophoneus is included in the Anteosauridae by Boonstra 1969
Archaeosyodon may be a Titanosuchid
Brithopus
Chthomaloporus
Deuterosaurus is a herbivorous genus that is sometimes placed in its own family.
Doliosauriscus (originally Doliosaurus) is included in Anteosauridae sensu Boonstra 1969 and the Anteosaurini sensu Hopson & Barghusen 1986. It is considered closely related to Anteosaurus
Eosyodon is an American genus that was added by Everett Olson but is now known to be a chimera.
Mnemeiosaurus
Notosyodon is probably included under the Syodontidae of Ivakhnenko 1994
Syodon is probably included under the Syodontidae of Ivakhnenko 1994
Titanophoneus is listed as Brithopodid by Carroll 1988, and Anteosaurinae by Hopson & Barghusen 1986.

A number of other forms have been discovered since, in South Africa (Australosyodon) and China (Stenocybus, Sinophoneus). However with the cladistic revolution, the name "Brithopodidae" is now falling out of fashion in favour of "Anteosauria", and so they are generally not included in the family.

[edit] References

Boonstra, L. D. 1963, Diversity within the South African Dinocephalia. S. Afr. J. Sci. 59: 196-206.
----- 1969, "The Fauna of the Tapincephalus Zone (Beaufort Beds of the Karoo)," Ann. S. Afr. Mus. 56 (1) 1-73, pp. 35-38
Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, WH Freeman & Co.
Chudinov, P. K. 1965, "New Facts about the Fauna of the Upper Permian of the USSR", Journal of Geology, 73:117-30
Hopson, J.A. and Barghusen, H.R. (1986), An analysis of therapsid relationships in N Hotton, III, PD MacLean, JJ Roth and EC Roth, The Ecology and Biology of Mammal-like Reptiles, Smithsonian Institute Press, pp. 83-106
King, G. M., 1988 "Anomodontia" Part 17 C, Encyclopedia of Paleoherpetology, Gutsav Fischer Verlag, Stuttgart and New York,
Olsen, E. C., 1962, Late Permian terrestrial vertebrates, USA and USSR Transactions of the American Philosophical Society, new series, 52: 1–224.
Rubidge, B.S. & Sidor, C.A. 2001, Evolutionary patterns among Permo-Triassic therapsids. Ann. Rev. Ecol. Syst. 32: 449-480.