Sphenacodontia
| Sphenacodontia Temporal range: Late Pennsylvanian-Recent,
| |
|---|---|
| File:Dimetrodon grandis 3D Model Reconstruction.png | |
| 3D restoration of Dimetrodon grandis, a sphenacodontid | |
| File:Alopecognathus angusticeps DB.jpg | |
| Restoration of a pair of Alopecognathus angusticeps, a therocephalian therapsid | |
| Scientific classification Edit this classification | |
| 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".[4] 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).
Characteristics
[edit | edit source]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
[edit | edit source]
The following taxonomy follows Fröbisch et al. (2011), Benson (2012) and Spinder (2016) unless otherwise noted.[3][4][5]
Class Synapsida
- Eupelycosauria
- Sphenacodontia
Phylogeny
[edit | edit source]Sphenacodontia in a cladogram after Fröbisch et al., 2011:[5]
See also
[edit | edit source]References
[edit | edit source]- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b 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
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- Laurin, M. and Reisz, R. R., 1997, Autapomorphies of the main clades of synapsids - Tree of Life Web Project
External links
[edit | edit source]
.jpg){kind=link}
Lua error in Module:Taxonbar at line 165: attempt to index field 'wikibase' (a nil value).