Sphenacodontoids Temporal range:
Late Carboniferous-Recent,
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Fossilized skull of two sphenacodontoids: Clelandina ( Therapsida, Gorgonopsidae) and a Dimetrodon ( Sphenacodontidae). | |
Scientific classification
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Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | Sphenacomorpha |
Clade: | Sphenacodontia |
Clade: | Pantherapsida |
Clade: |
Sphenacodontoidea Marsh, 1878 |
Clades | |
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). [1] Sphenacodontoids are characterised by a number of synapomorphies concerning proportions of the bones of the skull and the teeth. [2] [3]
The sphenacodontoids evolved from earlier sphenacodonts such as Haptodus and Ianthodon via a number of transitional stages of small, 1-10 kg, faunivore animals. [1] 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. [2] The first predators among Sphenacodontoidea, like Shashajaia, appeared in the tropical western part of Pangea in the Late Carboniferous. [1] Later, in Permian, sphenacodontoids gave rise to the dominant terrestrial carnivores in both sphenacodontid and therapsid groups. [2]
The following taxonomy follows Fröbisch et al. (2011) and Benson (2012) unless otherwise noted. [4] [5]
Class Synapsida
Sphenacodontoidea in a cladogram modified from Huttenlocker et al. (2021): [1]
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