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Sphenacodontia

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This is an old revision of this page, as edited by TheRealLTG (talk | contribs) at 19:27, 6 January 2021 (The Pennsylvanian Epoch was almost over back at 299.9 million years ago, which in case it ended 298.9 million years ago. Added the hyperlink on "Recent" on the taxobox to Holocene.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Sphenacodonts
Temporal range: Latest Pennsylvanian-Recent, 299.9–0 Ma
CG restoration of Dimetrodon homogenes
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Eupelycosauria
Clade: Metopophora
Clade: Haptodontiformes
Clade: Sphenacomorpha
Clade: Sphenacodontia
Genera and Clades

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 epoch.

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.

Characteristics

The defining characteristics include a thickening of the maxilla visible on its internal surface, above the large front (caniniform) teeth; and the premaxillary teeth being set in deep sockets. All other (sister group and more primitive) synapsid clades have teeth that are set in shallow sockets.

Classification

Pantelosaurus, from the Early Permian
Secodontosaurus, Early Permian

The following taxonomy follows Fröbisch et al. (2011) and Benson (2012) unless otherwise noted.[2][3][4]

Class Synapsida

See also

References

  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. ^ a b Benson, R.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Palaeontology. 10 (4): 601–624. doi:10.1080/14772019.2011.631042.
  3. ^ "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}}: Unknown parameter |authors= ignored (help)
  4. ^ https://pdfs.semanticscholar.org/9c44/ab6ded322debc7895dba871e4b06ea2a36f1.pdf
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