Pelycosaurs
| Pelycosaurs | ||||||||||||||
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Obsolete systematic group The taxon dealt with here is not part of the systematics presented in the German-language Wikipedia. More information can be found in the article text. |
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Live reconstructions of (back to front) Cotylorhynchus , Ophiacodon, and Varanops |
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| Temporal occurrence | ||||||||||||||
| Upper Carbon to Middle Perm | ||||||||||||||
| 310 to 260 million years | ||||||||||||||
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| Scientific name | ||||||||||||||
| Pelycosauria | ||||||||||||||
| Cope , 1878 | ||||||||||||||
The primitive synapsids of the late Paleozoic are called pelycosaurs (Pelycosauria) . The therapsids (Therapsida), the ancestors of mammals (Mammalia), emerged from them . The latter two groups are classically contrasted with the pelycosaurs. In the cladistic-based phylogenetic system, however , the pelycosaurs are an open family group (Paraphylum) and represent only a sequence of the earliest stages of development in the evolutionary history of the synapsids, in which the more modern forms are more closely related to the therapsids than to the more primitive forms.
The pelycosaurs had a reptilian appearance; they had elongated bodies and moved in splay gait . Some of the largest of them had backsails, which were made of vertebral processes covered with skin , giving them a kite-like appearance. These sails were probably well supplied with blood and thus helped the animals to regulate their body temperature: If the sun appeared in the morning, the animals , who had cooled down during the night without the sail, would have needed hours to be able to become active again; on the other hand, the sail could also be placed with the edge facing the sun and used for cooling.
The best-known and largest pelycosaurs are Dimetrodon ("two types of teeth"), one to 3.5 m tall carnivore, and the herbivore Edaphosaurus , about the same size. They lived in the early Permian , about 280 million years ago. In the former, at least, there are signs of the development of different teeth, but it still has a typical reptilian lower jaw, consisting of three bones. For the most part, smaller pelycosaurs did not need a sail and did not have one, like the up to 4 m long ophiacodon .
In any case, one can draw a direct line of descent from the pelycosaurs via the therapsids to the mammals and thus also to humans. The pelycosaurs, however, are not closely related to the dinosaurs that live much later . Later pelycosaurs, such as the carnivore Wagontia from the South African Permian, are also classified under the early therapsids.
Systematics
- Pelycosauria (Pelycosaurier)
literature
- Robert L. Carroll: Paleontology and Evolution of the Vertebrates. Thieme-Verlag, Stuttgart, 1993, ISBN 3-13-774401-6 .
