Seymouriamorpha

Seymouriamorpha
Fossil of Seymouria in the National Museum of Natural History
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Reptiliomorpha (?)
Order: Seymouriamorpha
Watson, 1917
Subgroups

See text.

Seymouriamorpha were a small but widespread group of limbed vertebrates (tetrapods). 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). Many seymouriamorphs were terrestrial or semi-aquatic. However, aquatic larvae bearing external gills and grooves from the lateral line system have been found, making them unquestionably amphibians. Though 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. Seymouriamorphs form into three main groups, Kotlassiidae, Discosauriscidae, and Seymouriidae, a group that includes the best known genus, Seymouria. The last seymouriamorph became extinct by the end of the Permian.

Taxonomy

Cladogram based on Ruta, Jeffery, & Coates (2003):

Seymouriamorpha

Kotlassia

Utegenia

Seymouria baylorensis

Seymouria sanjuanensis

Ariekanerpeton

Discosauriscus austriacus

Discosauriscus pulcherrimus

Cladogram based on Klembara (2009) & Klembara (2010):

Seymouriamorpha

Utegenia

Seymouria

Karpinskiosaurus

Discosauriscidae

Makowskia

Spinarerpeton

Ariekanerpeton

Discosauriscus

Gallery


This page was last updated at 2024-03-07 00:58 UTC. Update now. View original page.

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