Eucynodontia ("true dog teeth") is a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

cynodont Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 Megaannum, mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extin ...

therapsids including mammals and most non-mammalian cynodonts. The oldest eucynodonts are known from the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

and possibly

Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

. Eucynodontia includes two major subgroups,

Cynognathia Cynognathia ("dog jaw") is one of two major clades of cynodonts, the other being Probainognathia. Cynognathians included the large carnivorous genus '' Cynognathus'' and the herbivorous or omnivorous gomphodonts such as traversodontids. Cynogn ...

and

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 b ...

. The clade was named in 1982 by

Thomas Kemp Thomas Kemp may refer to: *Thomas Read Kemp (1783–1844), English property developer and politician *Thomas Webster Kemp (1866–1928), Royal Navy admiral *Thomas Kemp of the Kemp baronets *Thomas Kemp (shipbuilder) *Tom Kemp (1921–1993), Marxi ...

, who defined it as all cynodonts more derived than ''

Thrinaxodon ''Thrinaxodon'' is an extinct genus of cynodonts which lived in what are now South Africa and Antarctica during the Late Permian - Early Triassic. ''Thrinaxodon'' lived just before, during, and right after the Permian–Triassic mass extinction ...

''. In 2001,

Hopson Hopson is a surname. Notable people with the name Hopson include: *Briggs Hopson (born 1965), Republican member of the Mississippi Senate *Dennis Hopson (born 1965), American basketball player and coach *Eben Hopson (1922–1980), Alaskan Native Am ...

and Kitching redefined the clade Eucynodontia as the least inclusive group containing

Mammalia A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bon ...

and ''

Exaeretodon ''Exaeretodon'' is an Extinction, extinct genus of fairly large, low-slung traversodontid cynodonts from the southern parts of Pangea. Four species are Knowledge, known, hailing from various geologic formation, formations. ''E. argentinus'' is fr ...

''.James A. Hopson and James W. Kitching, 2001, "A Probainognathian Cynodont from South Africa and the Phylogeny of Nonmammalian Cynodonts" pp 5-35 in: PARISH A. JENKINS, JR., MICHAEL D. SHAPIRO, AND TOMASZ OWERKOWICZ, EDITORS, ''STUDIES IN ORGANISMIC AND EVOLUTIONARY BIOLOGY IN HONOR OF A. W. CROMPTON'' Bullettin of the Museum of Comparative Zoology. Harvard University 156(1)

Phylogeny

Cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

after Stefanello ''et al''. (2023):

References

Epicynodontia Extant Early Triassic first appearances {{Cynodont-stub