Seymouriamorpha
Extinct order of tetrapodomorphs
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Seymouriamorpha are an extinct group of tetrapods (terrestrial vertebrates) known from the Carboniferous and Permian periods. They have long been considered stem-amniotes (reptiliomorphs), and most paleontologists still accept this point of view, but some analyses suggest that seymouriamorphs are stem-tetrapods (not more closely related to Amniota than to Lissamphibia).[2] Seymouriamorphs are divided into three main groups: Kotlassiidae, Discosauriscidae, and Seymouriidae, which includes the best-known genus, Seymouria. The last seymouriamorphs became extinct by the end of the Permian.[3]
| Seymouriamorpha | |
|---|---|
| |
| Fossil of Seymouria in the National Museum of Natural History | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Reptiliomorpha (?) |
| Order: | †Seymouriamorpha Watson, 1917 |
| Subgroups | |
Many seymouriamorphs were terrestrial or semi-aquatic. However, aquatic larvae bearing external gills and grooves from the lateral line belonging to the seymouriamorph family Discosauriscidae have been found,[4][5] making seymouriamorphs unquestionably non-amniotes. As they matured, they became more terrestrial and reptile-like. They ranged from 30 cm (1 ft) long lizard-sized creatures to the 1.5 m (5 ft) long Enosuchus. If seymouriamorphs are reptiliomorphs, they were the distant relatives of amniotes.
They have been considered to be the makers of the trace fossils placed in the ichnogenus Amphisauropus.[6]
Taxonomy
- Biarmica
- Enosuchus
- Kotlassia
- Leptoropha
- Microphon
- Nyctiboetus
- Utegenia
- Waggoneria[7]
- Family Karpinskiosauridae
- Family Discosauriscidae
- Family Seymouriidae
Cladogram based on Ruta, Jeffery, & Coates (2003):[8]
| Seymouriamorpha | |
Cladogram based on Klembara (2009) & Klembara (2010):[9][10]
| Seymouriamorpha |
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