page_title: Therapsid
section_title: Classification
hierarchical_section_title: Therapsid / Taxonomy / Classification
caption_attribution_description: Estemmenosuchus mirabilis, a dinocephalian from the Middle Permian of Russia, pencil drawing &amp; digital coloring
context_page_description: Therapsida is a group of eupelycosaurian synapsids that includes mammals and their ancestors. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, as opposed to the sprawling posture of many reptiles and salamanders. The earliest fossil attributed to Therapsida is Tetraceratops insignis from the Lower Permian.
  Therapsids evolved from "pelycosaurs", specifically within the Sphenacodontia, more than 275 million years ago. They replaced the "pelycosaurs" as the dominant large land animals in the Middle Permian and were largely replaced, in turn, by the archosauromorphs in the Triassic, although one group of therapsids, the kannemeyeriiforms, remained diverse in the Late Triassic.
  The therapsids included the cynodonts, the group that gave rise to mammals in the Late Triassic around 225 million years ago. Of the non-mammalian therapsids, only cynodonts survived the Triassic–Jurassic extinction event. The last of the non-mammalian therapsids, the tritylodontid cynodonts, became extinct in the Early Cretaceous, approximately 100 million years ago.
context_section_description: Class Synapsida
  ORDER THERAPSIDA *
  ?Family † Tetraceratopsidae
  Suborder † Biarmosuchia *
  Family † Biarmosuchidae
  Family † Eotitanosuchidae
  Eutherapsida
  Suborder † Dinocephalia
  Family † Estemmenosuchidae
  ?Infraorder † Anteosauria
  Family † Anteosauridae
  Family † Brithopodidae
  Family † Deuterosauridae
  Family † Syodontidae
  ?Family † Stenocybidae
  † Tapinocephalia
  Family † Styracocephalidae
  Family † Tapinocephalidae
  Family † Titanosuchidae
  Neotherapsida
  Suborder † Anomodontia *
  Superfamily † Venyukoviamorpha
  Family † Otsheridae
  Family † Venyukoviidae
  Infraorder † Dromasauria
  Family † Galeopidae
  Infraorder † Dicynodonta
  Family † Endothiodontidae
  Family † Eodicynodontidae
  Family † Kingoriidae
  (Unranked) † Diictodontia
  Superfamily † Emydopoidea
  Family † Cistecephalidae
  Family † Emydopidae
  Superfamily † Robertoidea
  Family † Diictodontidae
  Family † Robertiidae
  (Unranked) † Pristerodontia
  Family † Aulacocephalodontidae
  Family † Dicynodontidae
  Family † Kannemeyeriidae
  Family † Lystrosauridae
  Family † Oudenodontidae
  Family † Pristerodontidae
  Family † Shanisiodontidae
  Family † Stahleckeriidae
  Theriodontia *
  Suborder † Gorgonopsia
  Family † Gorgonopsidae
  Eutheriodontia
  Suborder † Therocephalia
  Family † Lycosuchidae
  (Unranked) † Scylacosauria
  Family † Scylacosauridae
  Infraorder †Eutherocephalia
  Family † Hofmeyriidae
  Family † Moschorhinidae
  Family † Whaitsiidae
  Superfamily Baurioidea
  Family † Bauriidae
  Family † Ericiolacteridae
  Family † Ictidosuchidae
  Family † Ictidosuchopsidae
  Family † Lycideopsidae
  Suborder Cynodontia *
  Family † Dviniidae
  Family † Procynosuchidae
  (Unranked) Epicynodontia
  Family † Galesauridae
  Family † Thrinaxodontidae
  Infraorder Eucynodontia
  (Unranked) † Cynognathia
  Family † Cynognathidae
  Family † Diademodontidae
  Family † Traversodontidae
  Family † Trirachodontidae
  Family † Tritylodontidae
  (Unranked) Probainognathia
  Family † Chiniquodontidae
  Family † Probainognathidae
  (Unranked) † Ictidosauria
  Family † Tritheledontidae
  (Unranked) Mammaliaformes
  Class Mammalia
caption: Estemmenosuchus, a dinocephalian
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