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).[2] 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.[3]
^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.
doi:
10.2992/0097-4463-77.4.451.
