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 variet ...

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 mos ...

. Cynognathians included the large carnivorous genus ''

Cynognathus ''Cynognathus'' is an extinct genus of large-bodied cynodontian therapsids that lived in the Middle Triassic. It is known from a single species, ''Cynognathus crateronotus''. ''Cynognathus'' was a long predator closely related to mammals and ha ...

'' and the herbivorous

traversodontid 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. T ...

s. 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 hav ...

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 zygom ...

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 a ...

. 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 co ...

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 ...

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 subcontinent of Eurasia and it is located enti ...

, North America 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 souther ...

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 *****''

'' ****(unranked)

Gomphodontia Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent ...

*****Family Diademodontidae ******'' 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 Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent wit ...

******Family

Trirachodontidae Trirachodontidae is an extinct, possibly paraphyletic family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quick ...

*******Subfamily

Trirachodontinae Trirachodontidae is an extinct, possibly paraphyletic family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quick ...

********'' 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 Trirachodontidae is an extinct, possibly paraphyletic family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quick ...

********''

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 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. T ...

*******''

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'' *******''

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'' ********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 ''Plinthogomphodon'' is an extinct genus of traversodontid cynodonts from the Late Triassic of the eastern United States. Fossils have been found from the Deep River basin of North Carolina, part of the larger Newark Supergroup. It is known ...

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

Habayia ''Habayia'' is an extinct genus of traversodontid cynodonts from the Late Triassic of Belgium. A single postcanine tooth was found in Habay-la-Vieille in southern Belgium. Based on the size of the tooth, ''Habayia'' was very small. ''Habayia' ...

'' *********'' Maubeugia'' *********'' Microscalenodon'' *********'' Mandagomphodon'' *********''

Rosieria ''Rosieria'' is an extinct genus of dwarf cynodonts from the Late Triassic of France. It belongs to the family Traversodontidae, a herbivorous group known mainly from Gondwana Gondwana () was a large landmass, often referred to as a su ...

'' ********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 ''Gomphodontosuchus'' is an extinct genus of cynodonts. It was created to describe the species ''Gomphodontosuchus brasiliensis''. Species ''Gomphodontosuchus brasiliensis'' was first collected in 1928 by Friedrich von Huene in Santa Maria Forma ...

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

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 ''Protuberum'' is an extinct genus of traversodontid cynodonts known from a single species ''Protuberum cabralense'',The specific name ''cabralense'' is "necessarily emended from the original ''P. cabralensis'' because ''Protuberum'' is a neuter ...

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

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 ''Exaeretodon'' is an extinct genus of fairly large, low-slung traversodontid cynodonts from the southern parts of Pangea. Four species are known, from various formations. ''E. argentinus'' is from the Carnian-age (Late Triassic) Cancha de Boch ...

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

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