Seymouriamorpha were a small but widespread group of limbed vertebrates (

tetrapods Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...

). They have long been considered reptiliomorphs, and most paleontologists may still accept this point of view, but some analyses suggest that seymouriamorphs are stem-tetrapods (not more closely related to Amniota than to

Lissamphibia The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs, toads, and their extinct relatives), the Caudata (salamanders, newts, and their extinct relative ...

). Many seymouriamorphs were terrestrial or semi-aquatic. However, aquatic

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. Th ...

e bearing external

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

s and grooves from the lateral line system have been found, making them unquestionably amphibians. The adults were terrestrial. They ranged from

lizard Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia al ...

-sized creatures (30 centimeters) to

crocodile Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant ...

-sized 150 centimeter long

animals Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

. They were reptile-like. 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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

, '' Seymouria''. The last seymouriamorph became extinct by the end of the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

Taxonomy

* Reptiliomorpha *Order Seymouriamorpha **'' Biarmica'' **'' Enosuchus'' **'' Kotlassia'' **'' Leptoropha'' **'' Microphon'' **'' Nyctiboetus'' **'' Utegenia'' **'' Waggoneria'' **Family Karpinskiosauridae ***'' Karpinskiosaurus'' **Family Discosauriscidae ***'' Ariekanerpeton'' ***'' Discosauriscus'' ***'' Makowskia'' ***'' Spinarerpeton'' **Family Seymouriidae ***'' Seymouria''

Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

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

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

Gallery

File:Kotlassia prima1DB.jpg, '' Kotlassia'' File:Karpinskiosaurus1DB.jpg, '' Karpinskiosaurus''

References

External links

Bystrow, A.P. ''Kotlassia prima'' Amalitzky. Bulletin of the Geological Society of America, Washington, 1944, v.55, N5, pp.379-416.

- at Paleos
Seymouriamorpha
at

Tree of Life Web Project The Tree of Life Web Project is an Internet project providing information about the diversity and phylogeny of life on Earth. This collaborative peer reviewed project began in 1995, and is written by biologists from around the world. The site ...

Seymouriamorphs Cisuralian first appearances Lopingian extinctions {{permian-animal-stub