Seymouriamorpha
- Europe, Russia, Central Asia, North America
The Seymouriamorpha are an extinct group of early land vertebrates, whose fossil remains in Europe, Russia, Central Asia and North America were found.
There are three families distinguish terrestrial from all known from North America Seymouriidae that Discosauriscidae which are known only from lavalen or neotenen forms and Kotlassidae from the Upper Permian of Russia, who had reverted to an aquatic lifestyle.
Features
The Seymouriamorpha were about 50 to 100 cm long. Your axial skeleton is strong. The outer skull bones of adult animals were heavily sculpted by a hexagonal pattern. The palate was closed. The animals had ribs from the first cervical vertebra to the first caudal vertebrae. The ribs of the thoracic region were amplified. The spine was short, front of the sacrum, they had 24 to 28 vertebrae. The vertebrae had large, cylindrical Pleurocentra and small, crescent-shaped Intercentra and thus bear witness to the development of Pleurocentrum the most important element of the vertebrae in the amniotes to. The limbs were strong and stocky. Humerus and femur were strongly built. The Phalangenformel the forefoot is 2,3,4,4,3 or 2,3,4,5,3; of the hind foot 2,3,4,5,3.
Larval Seymouriamorpha and Discosauriscidae had only a weakly ossified skeleton, three pairs of external gills ( in the fossil record as carbonaceous shadow passed down ) and lateral line canals, as well as any and electric receptors.
System
The Seymouriamorpha been a long time, lavaler until the discovery of fossils Seymouriamorphen than the original group of Amniota or considered primitive amniotes. Other scientists saw in them amphibians. However, they are not closely related to the present-day amphibians ( Lissamphibia )
Benton them, together with the Diadectomorpha in the root group of the amniotes
- Seymouriidae Seymouria
- Discosauriscus
- Buzulukia
- Karpinskiosaurus
- Kotlassia