Sphenacodontoidea

Sphenacodontoids; Temporal range: Late Carboniferous-Recent, 300–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Examples of Sphenacodontoidea: Inostrancevia, Dimetrodon and Adelobasileus.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Clade:	Haptodontiformes
Clade:	Sphenacomorpha
Clade:	Sphenacodontia
Clade:	Pantherapsida
Clade:	Sphenacodontoidea
Clades
	†Sphenacodontidae; Therapsida;

Sphenacodontoidea is a node-based clade that is 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

^ "A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany" (PDF). Acta Palaeontologica Polonica. 56 (1): 113–120. 2011. doi:10.4202/app.2010.0039. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
^ Benson, R.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Palaeontology. in press (4): 601–624. doi:10.1080/14772019.2011.631042.