Sphenacodontoidea

Sphenacodontoids Temporal range: Late Carboniferous-Recent, 300–0 Ma PreЄ Є O S D C P T J K Pg N
Ctenospondylus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Sphenacodontia
Clade:	Sphenacodontoidea
Clades
†Sphenacodontidae Therapsida

Sphenacodontoidea is a node-based clade that defined to include 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.

Classification

The following taxonomy follows Fröbisch et al. (2011) and Benson (2012) unless otherwise noted.^[1][2]

Class Synapsida

• Sphenacodontoidea
  • Family †Sphenacodontidae
  • Therapsida

References

1. Jörg Fröbisch, Rainer R. Schoch, Johannes Müller, Thomas Schindler and Dieter Schweiss (2011). "A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany" (PDF). Acta Palaeontologica Polonica 56 (1): 113–120. doi:10.4202/app.2010.0039.
2. Benson, R.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Paleontology. in press. doi:10.1080/14772019.2011.631042.

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

See also

• Evolution of mammals