ancestral to modern amphibians) Order Anthracosauria (Carboniferous and Permian, e.g., Seymouria, ancestral to early reptiles) Subclass Lepospondyli (Carboniferous and Permian, e.g., Diplocaulus, small group, possibly ancestral to modern amphibians) Subclass Lissamphibia (Permian to present) Order Gymnophiona (extant) Order Urodela (extant) Order Anura (extant) Phylogenetic classification Labyrinthodontia has fallen out of favor in recent taxonomies because it is paraphyletic: the group does not include all the descendants of their most recent common ancestor. Various groups that have traditionally been placed within Labyrinthodontia are currently variously classified as stem tetrapods, basal tetrapods, non-amniote Reptiliomorpha and as a monophyletic or paraphyletic Temnospondyli, according to various cladistic analysis. This reflects the emphasis of ascertaining lineage and ancestral-descendant relatedness in modern-day cladistics. The name does however linger as a handy reference for the early amphibian tetrapods, and as an apt anatomical description of their distinct tooth pattern. Thus it remains in use as an informal term of convenience by some modern scientists. The largely synonymous name Stegocephalia has been taken up by Michel Laurin and defined cladistically for all traditional labyrinthodonts (including their descendants), so that the name with the largely traditional meaning is still employed. An informal term with a broader meaning is stem tetrapod, a stem group consisting of all species more closely related to modern tetrapods than to lungfish, but excluding the crown group. This group includes both traditional "labyrinthodonts" as well as more basal tetrapodomorph fish, though its total content is a matter of some uncertainty, as the relationships of these animals are not well understood. Below is a suggested evolutionary tree of Labyrinthodontia, from Colbert 1969 and Caroll 1997. Dashed lines indicate relationships that commonly vary between authors. A good summary (with diagram) of characteristics and main evolutionary trends of the above three orders is given in Colbert 1969 pp. 102–103, but see Kent & Miller (1997) for an alternative tree. See also Amphibian Batrachosauria Prehistoric amphibian Prehistoric life Reptiliomorpha Temnospondyli Tetrapod References External links Palaeos.com Cladogram of Reptiliomorpha Comparative Vertebrate Anatomy Mesozoic amphibians Paleozoic amphibians Paraphyletic groups Taxa named by Richard Owen