Sphenacodontoidea

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Sphenacodontoidea Fossil range: Early - Middle Permian (non-therapsid)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Synapsida Order: Pelycosauria (unranked) Eupelycosauria (unranked) Sphenacodontia (unranked) Sphenacodontoidea
Genera and Clades
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 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.

[edit] Taxonomy and Phylogeny

• Suborder Eupelycosauria
  • Sphenacodontia
    • Sphenacodontoidea
      • Family Sphenacodontidae
        • Ctenospondylus
        • Dimetrodon
        • Secodontosaurus
        • Sphenacodon
      • Tetraceratops
        • ORDER THERAPSIDA
          • Class Mammalia

[edit] Reference

• Laurin, M. and Reisz, R. R., 1997, Autapomorphies of the main clades of synapsids - Tree of Life Web Project