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The '''Eutheriodontia''' are a [[clade]] of [[therapsid]]s that includes [[therocephalian]]s and [[cynodont]]s.
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'''Eutheriodontia''' is a [[clade]] of [[therapsid]]s that includes [[therocephalian]]s and [[cynodont]]s. The clade was erected in 1986, and a close relationship between therocephalians and cynodonts has been recognized for many years. Therocephalians and cynodonts are thought to have diverged in the [[Middle Permian]], and each group independently evolved mammal-like features, including a [[secondary palate]] and the loss of a [[postorbital bar]] (these features were retained in mammals, which are considered a [[Synapomorphy|derived]] group of cynodonts). Mammalian features that both groups inherited from a common ancestor include the loss of teeth on the [[palate]], the expansion of the epipterygoid bone at the base of the skull (an area called the [[alisphenoid]] in mammals), and the narrowing of the [[skull roof]] to a narrow [[sagittal crest]] running between large [[temporal fenestrae|temporal openings]].<ref name=RS01>{{cite journal |last=Rubidge |first=B.S. |author2=Sidor, C.A. |year=2001 |title=Evolutionary patterns among Permo-Triassic therapsids |journal=Annual Review of Ecology, Evolution, and Systematics |volume=32 |pages=449–480 |url=http://www11.cac.washington.edu/burkemuseum/collections/paleontology/sidor/Rubidge_Sidor2001.pdf |doi=10.1146/annurev.ecolsys.32.081501.114113 |deadurl=yes |archiveurl=https://web.archive.org/web/20120321142923/http://www11.cac.washington.edu/burkemuseum/collections/paleontology/sidor/Rubidge_Sidor2001.pdf |archivedate=2012-03-21 |df= }}</ref>

The clade was named in 1986 by [[James Hopson|James Allen Hopson]], the name meaning the "True Theriodontia". Within Hopson's system, the Eutheriodontia are the [[sister group]] of the [[Gorgonopsia]] within the [[Theriodontia]].<ref>Hopson J.A. and Barghusen H. 1986. "An analysis of therapsid relationships". pp. 83–106 in: Hotton N., MacLean P.D., Roth J.J., Roth E.C., eds. ''The Ecology and Biology of the Mammal-Like Reptiles''. Washington, DC: Smithsonian Institute Press</ref> A close relationship between therocephalians and cynodonts had been recognized for many years.

⚫
Therocephalians and cynodonts are thought to have diverged in the [[Middle Permian]], and each group independently evolved mammal-like features, including a [[secondary palate]] and the loss of a [[postorbital bar]] (these features were retained in mammals, which are considered a [[Synapomorphy|derived]] group of cynodonts). Mammalian features that both groups inherited from a common ancestor include the loss of teeth on the [[palate]], the expansion of the epipterygoid bone at the base of the skull (an area called the [[alisphenoid]] in mammals), and the narrowing of the [[skull roof]] to a narrow [[sagittal crest]] running between large [[temporal fenestrae|temporal openings]].<ref name=RS01>{{cite journal |last=Rubidge |first=B.S. |author2=Sidor, C.A. |year=2001 |title=Evolutionary patterns among Permo-Triassic therapsids |journal=Annual Review of Ecology, Evolution, and Systematics |volume=32 |pages=449–480 |url=http://www11.cac.washington.edu/burkemuseum/collections/paleontology/sidor/Rubidge_Sidor2001.pdf |doi=10.1146/annurev.ecolsys.32.081501.114113 |deadurl=yes |archiveurl=https://web.archive.org/web/20120321142923/http://www11.cac.washington.edu/burkemuseum/collections/paleontology/sidor/Rubidge_Sidor2001.pdf |archivedate=2012-03-21 |df= }}</ref>


==References==
==References==

Revision as of 08:39, 18 February 2019

Eutheriodontia
Temporal range: Middle Permian-Holocene, 265–0 Ma Non-mammalian synapsids died out 17.5 million years ago
Life restoration of the therocephalian Microgomphodon
Life restoration of the cynodont Tritylodon
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Clade: Theriodontia
Clade: Eutheriodontia
Hopson & Barghusen,

1986

Groups

†Therocephalia
Cynodontia

The Eutheriodontia are a clade of therapsids that includes therocephalians and cynodonts.

The clade was named in 1986 by James Allen Hopson, the name meaning the "True Theriodontia". Within Hopson's system, the Eutheriodontia are the sister group of the Gorgonopsia within the Theriodontia.[1] A close relationship between therocephalians and cynodonts had been recognized for many years.

Therocephalians and cynodonts are thought to have diverged in the Middle Permian, and each group independently evolved mammal-like features, including a secondary palate and the loss of a postorbital bar (these features were retained in mammals, which are considered a derived group of cynodonts). Mammalian features that both groups inherited from a common ancestor include the loss of teeth on the palate, the expansion of the epipterygoid bone at the base of the skull (an area called the alisphenoid in mammals), and the narrowing of the skull roof to a narrow sagittal crest running between large temporal openings.[2]

References

  1. ^ Hopson J.A. and Barghusen H. 1986. "An analysis of therapsid relationships". pp. 83–106 in: Hotton N., MacLean P.D., Roth J.J., Roth E.C., eds. The Ecology and Biology of the Mammal-Like Reptiles. Washington, DC: Smithsonian Institute Press
  2. ^ Rubidge, B.S.; Sidor, C.A. (2001). "Evolutionary patterns among Permo-Triassic therapsids" (PDF). Annual Review of Ecology, Evolution, and Systematics. 32: 449–480. doi:10.1146/annurev.ecolsys.32.081501.114113. Archived from the original (PDF) on 2012-03-21. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)


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