Seymouriamorpha were a small but widespread group of limbed vertebrates (tetrapods). They have long been considered reptiliomorphs, and most paleontologists still accept this point of view, but some analyses suggest that seymouriamorphs are stem-tetrapods (not more closely relates 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 has been found. The adults were terrestrial. They ranged from lizard-sized creatures (30 centimeters) to small crocodile-sized 150 centimeter long animals. They were reptile-like. If seymouriamorphs are reptiliomorphs, they were relatives of amniotes. Seymouriamorphs form into three main groups, Kotlassiidae, Discosauriscidae, and Seymouriidae, the latter group that includes the best known and type genus, Seymouria. The last seymouriamorph became extinct by the end of Permian.
In Walking with... SeriesEdit
The second half of this episode featured Seymouria, the most famous member of this group. It is also the only seymouriamorph that was featured in any of IP programs up to date. It was identified only as an 'amphibian' in the show, and was shown trying to steal Dimetrodon eggs, but a male Dimetrodon caught and killed it instead.