Sphenacodontia

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Haptodus (extinct) Sphenacodontia. Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin (2011) as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias".[1] They first appear during the Late Pennsylvanian epoch. The defining characteristics include a thickening of the maxilla visible on its internal surface, above the large front (caniniform) teeth; and the premaxillary teeth being set in deep sockets. All other (sister group and more primitive) synapsid clades have teeth that are set in shallow sockets.

Taxonomy and Phylogeny[edit] The following taxonomy follows Fröbisch et al. (2011) and Benson (in press) unless otherwise noted.[2][1] Class Synapsida References[edit] Laurin, M. and Reisz, R. See also[edit] Evolution of mammals External links[edit] Synapsida: Sphenacodontia.