Sphenacodontia


Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias". They first appear during the Late Pennsylvanian epoch.
Basal Sphenacodontia constitute a transitional evolutionary series from early pelycosaurs to ancestral therapsids. One might say that the Sphenacodontians are proto-therapsids.

Characteristics

The defining characteristics include a thickening of the maxilla visible on its internal surface, above the large front teeth; and the premaxillary teeth being set in deep sockets. All other synapsid clades have teeth that are set in shallow sockets.

Classification

of northeasten Germany
, Early Permian
The following taxonomy follows Fröbisch et al. and Benson unless otherwise noted.
Class Synapsida