Sphenacodontia
| Sphenacodontia | ||||||||||||
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Pantelosaurus |
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| Temporal occurrence | ||||||||||||
| Upper carbon to lower perm | ||||||||||||
| 305 to 272.5 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Sphenacodontia | ||||||||||||
| Marsh , 1878 |
The Sphenacodontia are a group of pelycosaurs , so they belong to the synapsid amniotes (Synapsida).
They were the dominant carnivorous land vertebrates in the Lower Permian . From an evolutionary point of view, it is significant that the therapsids , the ancestors of mammals (Mammalia) , emerged from them . The best known and best researched sphenacodont is the more than three meter long dimetrodon . It stands out for its spectacular back sail, which is also worn by some other members of the Sphenacodonts.
features
Like all Pelycosauria, the Sphenacodonts had a lizard-like, elongated shape with a long tail and short legs that protruded from the body. Her massive skull was tall and narrow. The large mouth had a differentiated carnivore bite with partially elongated front teeth in the upper and lower jaw and an elongated canine in the upper jaw. The teeth of the upper jaw sat in deep tooth sockets , in all other synapsids the alveoli are flat. The temporomandibular joint was well below the level of the rows of teeth.
The spinous processes of the back and cervical spine were elongated and carried the large sail in Ctenospondylus , Secodontosaurus and Dimetrodon , which was probably useful for thermoregulation , but could also have served for communication between conspecifics.
Systematics
- Sphenacodontia
literature
- Robert L. Carroll: Paleontology and Evolution of the Vertebrates. Thieme-Verlag, Stuttgart, 1993, ISBN 3-13774-401-6
- Thomas S. Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005. ISBN 0198507615