Seymouriamorpha Explained

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).^[1]

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. 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 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.^[2]

Taxonomy

• Biarmica
• Enosuchus
• Kotlassia
• Leptoropha
• Microphon
• Nyctiboetus
• Utegenia
• Waggoneria^[3]
• Family Karpinskiosauridae
  • Karpinskiosaurus
• Family Discosauriscidae
  • Ariekanerpeton
  • Discosauriscus
  • Makowskia
  • Spinarerpeton
• Family Seymouriidae
  • Seymouria

Cladogram based on Ruta, Jeffery, & Coates (2003):^[4]

Cladogram based on Klembara (2009) & Klembara (2010):^{[5] [6]}

External links

• Bystrow, A.P. Kotlassia prima Amalitzky. Bulletin of the Geological Society of America, Washington, 1944, v.55, N5, pp.379-416.
• Seymouriamorpha - at Paleos
• Seymouriamorpha at Tree of Life Web Project

Notes and References

1. Book: Laurin, Michel . How Vertebrates Left the Water. 2010. University of California Press. Berkeley. 978-0-520-26647-6.
2. Bulanov . V. V. . vanc . 2003 . Evolution and systematics of seymouriamorph parareptiles . Paleontological Journal . 37 . Supplement 1 . 1–105.
3. Olson . E. C. . 1951 . Fauna of upper Vale and Choza: 1-5 . Fieldiana Geology . 10 . 11 . 89–128 . 10.5962/bhl.title.3264. free .
4. Ruta . M. . Jeffery, J. E. . Coates, M. I. . 2003 . A supertree of early tetrapods . Proceedings of the Royal Society B . 270 . 2507–16 . 14667343 . 1532 . 10.1098/rspb.2003.2524 . 1691537.
5. Klembara . Jozef . 2009 . The skeletal anatomy and relationships of a new discosauriscid seymouriamorph from the lower Permian of Moravia (Czech Republic) . Annals of Carnegie Museum . 77 . 4 . 451–483 . 10.2992/0097-4463-77.4.451.
6. Klembara . Jozef . 2011 . The cranial anatomy, ontogeny, and relationships of Karpinskiosaurus secundus (Amalitzky) (Seymouriamorpha, Karpinskiosauridae) from the Upper Permian of European Russia . Zoological Journal of the Linnean Society . 161 . 1 . 184–212 . 10.1111/j.1096-3642.2009.00629.x. free .