Cynognathia ("dog jaw") is one of two major clades of

cynodont The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety ...

s, the other being

Probainognathia Probainognathia is one of the two major subgroups of the clade Eucynodontia, the other being Cynognathia. The earliest forms were carnivorous and insectivorous, though some groups eventually also evolved herbivorous diets. The earliest and most ...

. Cynognathians included the large carnivorous genus '' Cynognathus'' and the herbivorous traversodontids. Cynognathians can be identified by several

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

including a very deep

zygomatic arch In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygomati ...

that extends above the middle of the

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. Cynognathian fossils are currently known 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 ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Taxonomy

*Suborder Cynodontia **Infraorder

Eucynodontia Eucynodontia ("true dog teeth") is a clade of cynodont therapsids including mammals and most non-mammalian cynodonts. The oldest eucynodonts are known from the Early Triassic and possibly Late Permian. Eucynodontia includes two major subgroups, ...

***(unranked) Cynognathia ****Family Cynognathidae *****'' Cynognathus'' ****(unranked) Gomphodontia *****Family

Diademodontidae Diademodontidae is an extinct family of Triassic gomphodonts. The best-known genus is ''Diademodon'' from South Africa. '' Titanogomphodon'' from Namibia may also be a member of Diademodontidae. The Chinese genera '' Hazhenia'' and '' Ordosiodon' ...

******'' Diademodon'' ******''

Titanogomphodon ''Titanogomphodon'' is an extinct genus of diademodontid cynodonts from the Middle Triassic Omingonde Formation of Namibia. It is known from a single partial skull that was described in 1973 from the Omingonde Formation. The type and only species ...

'' *****(unranked) Neogomphodontia ******Family Trirachodontidae *******Subfamily Trirachodontinae ********'' Langbergia'' ********''

Trirachodon ''Trirachodon'' (Greek: "three ridge tooth") is an extinct genus of cynodonts. Fossils have been found in the ''Cynognathus'' Assemblage Zone of the Beaufort Group in South Africa and the Omingonde Formation of Namibia, dating back to the Early ...

'' *******Subfamily Sinognathinae ********''

Beishanodon ''Beishanodon'' is an extinct genus of eucynodonts from Lower Triassic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 ...

'' ********''

Sinognathus ''Sinognathus'' is an extinct genus of gomphodont cynodonts from the Middle Triassic Ermaying Formation of China. Its type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type ...

'' ********'' Cricodon'' ******Family Traversodontidae *******''

Etjoia ''Etjoia'' is an extinct genus of traversodontid cynodonts that lived during the Middle Triassic or Late Triassic period in southern Africa. This medium-sized omnivorous cynognathian provides important information on the dental evolution of ear ...

'' *******''

Nanogomphodon ''Nanogomphodon'' is an extinct genus of cynodonts which existed in Germany during the Middle Triassic period. ''Nanogomphodon'' were small herbivorous traversodontid gomphodonts. The type species is ''Nanogomphodon wildi''. They are only known ...

'' *******''

Scalenodon ''Scalenodon'' is an extinct genus of traversodontid cynodonts from the Middle Triassic of Africa and possibly Russia. The type species ''S. angustifrons'' was named in 1946 and several other species were named in the following years. Most of the ...

'' *******Subfamily

Traversodontinae Traversodontidae is an extinct family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and eastern North America. Tr ...

********''

Traversodon ''Traversodon'' is an extinct genus of cynodonts. It was a relative of the ancestor to modern mammals. ''Traversodon'' lived in what is now South America. Species ''Traversodon stahleckeri'' was first found by Friedrich von Huene in 1936 in th ...

'' ********'' Luangwa'' ******* Unnamed clade ********''

Andescynodon ''Andescynodon'' is a genus of traversodontid cynodonts from the Middle Triassic of Argentina. Fossils are known from the Cerro de las Cabras and Cacheutá Formations. ''Andescynodon'' is one of the most basal traversodontids. Another traverso ...

'' ********''

Pascualgnathus ''Pascualgnathus'' is an extinct genus of traversodontid cynodonts from the Middle Triassic of Argentina. Fossils have been found from the Río Seco de la Quebrada Formation of the Puesto Viejo Group. The type species ''P. polanskii'' was named ...

'' ********''

Mandagomphodon ''Mandagomphodon'' is an extinct genus of traversodontid cynodonts from the Middle Triassic Lifua Member of the Manda Beds of Ruhuhu Valley, Tanzania. The type species ''Mandagomphodon hirschsoni'' was named by Crompton in 1972 as a species refe ...

'' ********Subfamily

Massetognathinae Massetognathinae is an extinct subfamily of cynodonts in the family Traversodontidae. It includes four species from the Middle and Late Triassic: ''Massetognathus pascuali'' from Argentina, ''Massetognathus ochagaviae'' and '' Santacruzodon hop ...

*********''

Dadadon ''Dadadon'' is an extinct genus of traversodontid cynodonts which existed in Madagascar during the late Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three ...

'' *********''

Massetognathus ''Massetognathus'' ( ; Greek for "chewing muscle jaw") is an extinct genus of plant-eating traversodontid cynodonts. They lived during the Triassic Period about 235 million years ago, and are known from the Chañares Formation in Argentina and t ...

'' *********''

Santacruzodon ''Santacruzodon'' is an extinct genus of cynodonts which existed in Brazil during the Triassic period. The type species is ''Santacruzodon hopsoni''. Species ''Santacruzodon hopsoni'', is a species that was collected in 1995 in Santa Cruz do Sul ...

'' ********Subfamily

Arctotraversodontinae Arctotraversodontinae is a subfamily of Late Triassic cynodonts belonging to the family Traversodontidae. Members of the subfamily include '' Arctotraversodon'', '' Boreogomphodon'' and '' Plinthogomphodon'' from North America, and '' Habayia'' ...

*********''

Arctotraversodon ''Arctotraversodon'' is an extinct genus of traversodontid cynodonts from the Late Triassic of Canada. Fossils first described from the Wolfville Formation in Nova Scotia in 1984 represented the first known traversodontid from North America.Hops ...

'' *********''

Boreogomphodon ''Boreogomphodon'' is an extinct genus of traversodontid cynodonts from the Late Triassic of the eastern United States. Fossils have been found from the Turkey Branch Formation in Virginia. Description and history ''Boreogomphodon jeffersoni'' w ...

'' *********'' Plinthogomphodon'' *********'' Habayia'' *********'' Maubeugia'' *********'' Microscalenodon'' *********''

'' *********'' Rosieria'' ********Subfamily

Gomphodontosuchinae Gomphodontosuchinae is a subfamily of Triassic traversodontid cynodonts. It includes the genera ''Gomphodontosuchus'' (the type genus), ''Exaeretodon'', '' Menadon'', '' Protuberum'', '' Ruberodon'', '' Scalenodontoides'' and '' Siriusgnathus''. ...

*********'' Gomphodontosuchus'' *********''

Menadon ''Menadon'' is an extinct genus of traversodontid cynodonts. The type and only species is ''Menadon besairiei''. Fossils of ''Menadon'' were first found in Isalo II (the Makay Formation) of Madagascar, which preserves sediments from the Middl ...

'' *********'' Protuberum'' *********''

Ruberodon ''Ruberodon'' is an extinct genus of traversodontid cynodonts known from the type and only species ''Ruberodon roychowdhurii'' from the Late Triassic of India. ''Ruberodon'' was named in 2015 on the basis of several isolated lower jaws found in ...

'' *********''

Scalenodontoides ''Scalenodontoides'' is an extinct genus of traversodontidae, a family of herbivorous cynodonts. It lived during the Late Triassic in what is now South Africa. Its type species is ''Scalenodontoides macrodontes''. It was named in 1957 by A. W. Cr ...

'' *********'' Exaeretodon'' *********''

Siriusgnathus ''Siriusgnathus'' is a traversodontid cynodont from the Carnian channel sandstones and mudstones of the Candelária Formation, belonging to the Santa Maria Supersequence of the Paraná Basin in southeastern Brazil.

References

{{Taxonbar, from=Q5199968 Early Triassic first appearances Late Triassic extinctions Tetrapod unranked clades Taxa named by James Hopson

Taxonomy

See also

References