Reptiliomorphs
| Reptiliomorpha Temporal range: Mississippian–Present, 340–0 Ma |
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| Mounted skeleton of Diadectes, American Museum of Natural History | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Superclass: | Tetrapoda |
| Clade: |
Reptiliomorpha Säve-Söderbergh, 1934 |
| Groups | |
Reptiliomorpha is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians (lissamphibians). It was defined by Michel Laurin (2001) and Vallin and Laurin (2004) as the largest clade that includes Homo sapiens, but not Ascaphus truei.
The informal variant of the name, "reptiliomorphs", is also occasionally used to refer to stem-amniotes, i.e. a grade of reptile-like labyrinthodont tetrapods that are more closely related to amniotes than they are to lissamphibians, but are not amniotes themselves; the name is used in this meaning e.g. by Ruta, Coates and Quicke (2003). An alternative name, "Anthracosauria", is also commonly used for the group, but is confusingly also used for the more primitive grade of reptiliomorphs by Benton.
As the exact phylogenetic position of Lissamphibia within Tetrapoda remains uncertain, it also remains controversial which fossil tetrapods are more closely related to amniotes than to lissamphibians, and thus, which ones of them were reptiliomorphs in any meaning of the word.
The name Reptiliomorpha was coined by Professor Gunnar Säve-Söderbergh in 1934 to designate amniotes and various types of late Paleozoic tetrapods that were more closely related to amniotes than to living amphibians. In his view, the amphibians had evolved from fish twice, with one group composed of the ancestors of modern salamanders and the other, which Säve-Söderbergh referred to as Eutetrapoda, consisting of anurans (frogs), amniotes and their ancestors, with the origin of caecilians being uncertain. Säve-Söderbergh's Eutetrapoda consisted of two sister-groups: Batrachomorpha, containing anurans and their ancestors, and Reptiliomorpha, containing anthracosaurs and amniotes. Säve-Söderbergh subsequently added Seymouriamorpha to his Reptiliomorpha as well.
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