- Source: Sphenacodontoidea
Sphenacodontoidea is a node-based clade that is defined to include the most recent common ancestor of Sphenacodontidae and Therapsida and its descendants (including mammals). Sphenacodontoids are characterised by a number of synapomorphies concerning proportions of the bones of the skull and the teeth.
The sphenacodontoids evolved from earlier sphenacodonts such as Haptodus and Ianthodon via a number of transitional stages of small, 1-10 kg, faunivore animals. The possible common ancestor of sphenacodontids and therapsids was a carnivorous synapsid that reached moderate or large size and more closely resembled the land-dominant Early Permian sphenacodontids than the small Haptodus. The first predators among Sphenacodontoidea, like Shashajaia, appeared in the tropical western part of Pangea in the Late Carboniferous. Later, in Permian, sphenacodontoids gave rise to the dominant terrestrial carnivores in both sphenacodontid and therapsid groups.
Classification
The following taxonomy follows Fröbisch et al. (2011) and Benson (2012) unless otherwise noted.
Class Synapsida
Sphenacodontoidea
Family †Sphenacodontidae
Therapsida
= Phylogeny
=Sphenacodontoidea in a cladogram modified from Huttenlocker et al. (2021):
See also
Evolution of mammals
References
Further reading
Laurin, M. and Reisz, R. R., 1997, Autapomorphies of the main clades of synapsids - Tree of Life Web Project
External links
"Synapsida". Mikko's Phylogeny Archive. Archived from the original on September 3, 2007.