Sphenacodontoidea
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Sphenacodontoidea is the name given to the monophyletic 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 [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
Reference
- Laurin, M. and Reisz, R. R., 1997, [Autapomorphies of the main clades of synapsids] - Tree of Life Web Project
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