Sphenacodontia


Sphenacodonts
Temporal range: Late Pennsylvanian-Recent,
Dimetrodon grandis 3D Model Reconstruction.png
3D restoration of Dimetrodon grandis
Inostrancevia preys on a juvenile Scutosaurus.png
Restoration of the gorgonopsid therapsid Inostrancevia feasting on the carcass of a young Scutosaurus (a pareiasaurid parareptile)
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Sphenacomorpha
Clade: Sphenacodontia
Romer & Price, 1940
Subgroups

Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin (2011) as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias".[2] They first appear during the Late Pennsylvanian (Upper Carboniferous) epoch. From the end of the Carboniferous to the end of the Permian, most of them remained large, with only some secondarily becoming small in size.

Basal Sphenacodontia constitute a transitional evolutionary series from early pelycosaurs to ancestral therapsids (which in turn were the ancestors of more advanced forms and finally the mammals). One might say that the sphenacodontians are proto-therapsids (even though there is almost a 30-million-years gap between the separation of the ancestors of therapsids from other sphenacodontians and the first appearance of therapsids in the fossil record).

  1. ^ Spindler, F. 2016. Morphological description and taxonomic status of Palaeohatteria and Pantelosaurus (Synapsida: Sphenacodontia). Freiberger Forschungshefte C550(23): 1–57. https://www.researchgate.net/publication/321129043_Morphological_description_and_taxonomic_status_of_Palaeohatteria_and_Pantelosaurus_Synapsida_Sphenacodontia
  2. ^ Cite error: The named reference BRJ12 was invoked but never defined (see the help page).

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