Sphenacodontoidea

Taxobox
name = Sphenacodontoidea
fossil_range = Latest Carboniferous - Middle Permian (non-therapsid)

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image_caption = "Ctenospondylus"
regnum = Animalia
phylum = Chordata
classis = Synapsida
ordo = Pelycosauria
unranked_familia = Sphenacodontoidea
subdivision_ranks = Genera and Clades
subdivision =See Taxonomy

Sphenacodontoidea is the name given to the clade that includes the most recent common ancestor of the Sphenacodontidae and the Therapsida and their descendants (including mammals). They are defined according to a number of specialised characteristics concerning [http://tolweb.org/notes/?note_id=466 proportions of the bones of the skull and the teeth] .

The Sphenacodontoidea evolved from earlier Sphenacodontia such as "Haptodus" via a number of transitional stages of small, unspecialised pelycosaurs.

Taxonomy and Phylogeny

* Suborder Eupelycosauria
** Sphenacodontia
*** Sphenacodontoidea
**** Family Sphenacodontidae
***** "Ctenospondylus"
***** "Dimetrodon"
***** "Secodontosaurus"
***** "Sphenacodon"
**** "Tetraceratops"
***** "'ORDER THERAPSIDA
****** "'Class Mammalia

References

* Laurin, M. and Reisz, R. R., 1997, [http://tolweb.org/accessory/Synapsid_Classification_&_Apomorphies?acc_id=466 Autapomorphies of the main clades of synapsids] - Tree of Life Web Project

ee also

* Evolution of mammals