Lepospondyli is a diverse taxon of early tetrapods. With the exception of one late-surviving lepospondyl from the Late Permian of Morocco, lepospondyls lived from the Early Carboniferous (Mississippian) to the Early Permian and were geographically restricted to what is now Europe and North America. Five major groups of lepospondyls are known: Adelospondyli; Aïstopoda; Lysorophia; Microsauria; and Nectridea. Lepospondyls have a diverse range of body forms and include species with newt-like, eel- or snake-like, and lizard-like forms. Various species were aquatic, semiaquatic, or terrestrial. None were large, and they are assumed to have lived in specialized ecological niches not taken by the more numerous temnospondyl amphibians that coexisted with them in the Paleozoic. Lepospondyli was named in 1888 by Karl Alfred von Zittel, who coined the name to include some tetrapods from the Paleozoic, that shared some specific characteristics in the notochord and teeth. Lepospondyls have sometimes been considered to be either related or ancestral to modern amphibians or to Amniota. It has been suggested that the grouping is polyphyletic, with aïstopods being primitive stem-tetrapods, while microsaurs are primitive reptiles.
Dissorophoideans are a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the skull, and many forms seem to have been well adapted for life on land. Since 2008, Lissamphibia has been progressively widely considered part of this clade, but this position is still disputed by some authors.
Temnospondyli is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian, and Triassic periods. A few species continued into the Jurassic and Cretaceous periods. Fossils have been found on every continent. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including fresh water, terrestrial, and even coastal marine environments. Their life history is well understood, with fossils known from the larval stage, metamorphosis, and maturity. Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are considered amphibians, many had characteristics, such as scales, claws, and armour-like bony plates, that distinguish them from modern amphibians.
Eryopidae were a group of medium to large amphibious temnospondyli, known from North America and Europe. They are defined as all eryopoids with interpterygoid vacuities that are rounded at the front; and large external nares. Not all of the genera previously included in the Eryopidae are retained under the cladistic revisions.
Dvinosaurs are one of several new clades of Temnospondyl amphibians named in the phylogenetic review of the group by Yates and Warren 2000. They represent a group of primitive semi-aquatic to completely aquatic amphibians, and are known from the Late Carboniferous to the Early Triassic, being most common in the Permian period. Their distinguishing characteristics are a reduction of the otic notch; the loss of a flange on the rear side of the pterygoid; and 28 or more presacral vertebrae.
Trematosauria is one of two major groups of temnospondyl amphibians that survived the Permian-Triassic extinction event, the other being the Capitosauria. The trematosaurs were a diverse and important group that included many medium-sized to large forms that were semi-aquatic to totally aquatic. The group included long-snouted forms such as the trematosauroids and short, broad-headed forms such as the metoposaurs. Although most groups did not survive beyond the Triassic, one lineage, the brachyopoids, continued until the Cretaceous period. Trematosauria is defined as all stereospondyls more closely related to Trematosaurus than to Parotosuchus, a capitosaurian.
Euskelia is a clade of extinct Temnospondyl amphibians. Euskelia is a stem-based taxon including all temnospondyls more closely related to Eryops than to Parotosuchus.
Sclerocephalus is an extinct genus of temnospondyl amphibian from the lowermost Permian of Germany and Czech republic with four valid species, including the type species S. haeuseri. It is one of the most completely preserved and most abundant Palaeozoic tetrapods. Sclerocephalus was once thought to be closely related to eryopoid temnospondyls, but it is now thought to be more closely related to archegosauroids. It is the only genus in the family Sclerocephalidae.
Saharastega is an extinct genus of basal temnospondyl which lived during the Late Permian period, around 251 to 260 million years ago. Remains of Saharastega, discovered by paleontologist Christian A. Sidor at the Moradi Formation in Niger, were described briefly in 2005 and more comprehensively in 2006. The description is based on a skull lacking the lower jaws.
Brachyopoidea is a superfamily of temnospondyls that lived during the Mesozoic. It contains the families Brachyopidae and Chigutisauridae. The earliest records of brachyopids are from the Lower Triassic in Australia. The latest-surviving member of the superfamily is the chigutisaurid Koolasuchus from the Early Cretaceous of Australia.
Lydekkerinidae is a family of stereospondyl temnospondyls that lived in the Triassic period. During the Triassic, lydekkerinids had a global distribution. They were small-bodied with wedge-shaped, roughly triangular heads. Fossils have been found in Russia, Greenland, India, South Africa, Madagascar, and Australia. The type genus is Lydekkerina, the namesake of the family and the most well-known lydekkerinid.
Trematosauridae are a family of large marine temnospondyl amphibians with many members. They first appeared during the Induan age of the Early Triassic, and existed until around the Carnian stage of the Late Triassic, although by then they were very rare. By the Middle Triassic they had become widespread throughout Laurasia and Gondwana with fossils being found in Europe, Asia, Madagascar, and Australia.
Stereospondylomorpha is a clade of temnospondyls. It includes the superfamily Archegosauroidea and the more diverse group Stereospondyli. Stereospondylomorpha was first proposed by Yates and Warren (2000), who found Archegosauroidea and Stereospondyli to be sister taxa in their phylogenetic analysis. A similar clade is Archegosauriformes, named by Schoch and Milner (2000), which includes Stereospondyli and some Permian temnospondyls that are similar in appearance to stereospondyls, including the archegosauroids. However, according to Schoch and Milner's phylogeny, Archegosauroidea is a paraphyletic group of taxa that are successively basal to Stereospondyli, rather than a monophyletic sister taxon.
Limnarchia is a clade of temnospondyls. It includes the mostly Carboniferous-Permian age Dvinosauria and the mostly Permian-Triassic age Stereospondylomorpha. The clade was named in a 2000 phylogenetic analysis of stereospondyls and their relatives. Limnarchia means "lake rulers" in Greek, in reference to their aquatic lifestyles and long existence over a span of approximately 200 million years from the Late Carboniferous to the Early Cretaceous. In phylogenetic terms, Limnarchia is a stem-based taxon including all temnospondyls more closely related to Parotosuchus than to Eryops. It is the sister group of the clade Euskelia, which is all temnospondyls more closely related to Eryops than to Parotosuchus. Limnarchians represent an evolutionary radiation of temnospondyls into aquatic environments, while euskelians represent a radiation into terrestrial environments. While many euskelians were adapted to life on land with strong limbs and bony scutes, most limnarchians were better adapted for the water with poorly developed limbs and lateral line sensory systems in their skulls.
Rhytidosteoidea is a superfamily of Temnospondyli, early amphibian species that existed during the Carboniferous, Permian, and Triassic periods. The taxon was established in 1965 to accommodate two new species of Deltasaurus, the author recognising an alliance with previously described genera.
Almasaurus is an extinct genus of trematosaurian temnospondyl within the family Latiscopidae. It is known from several skulls and some postcranial material found from the Argana Formation in Morocco, which dates back to the Late Triassic.
Lapillopsis is an extinct genus of stereospondyl temnospondyl within the family Lapillopsidae. Fossils belonging to the genus have been found in the Arcadia Formation of Queensland, Australia.
Brachyopomorpha is a clade of stereospondyl temnospondyls within the infraorder Trematosauria. It was constructed in 2000 to include Bothriceps australis and the superfamily Brachyopoidea. It is phylogenetically defined as a stem-based taxon including Pelorocephalus and all taxa closer to it than to Rhytidosteus. In contrast, Brachyopoidea is defined as a node-based taxon including Brachyops and Pelorocephalus and all descendants of their most recent common ancestor. Because Bothriceps is not thought to be a descendant of that recent common ancestor and would be more basal than it, the genus is placed just outside Brachyopoidea and is considered to be a sister taxon to the clade.
Archegosauroidea is an extinct superfamily of Permian temnospondyls. The superfamily is assigned to the clade Stereospondylomorpha and is the sister taxon to the suborder Stereospondyli. It includes the families Actinodontidae and Archegosauridae, and possibly the genus Intasuchus, which is placed within the monotypic family Intasuchidae. They were fully aquatic animals, and were metabolically and physiologically more similar to fish than modern amphibians.
Capitosauria is an extinct group of large temnospondyl amphibians with simplified stereospondyl vertebrae. Mainly living as piscivores in lakes and rivers, the Capitosauria and its sister taxon Trematosauria were the only major labyrinthodonts that existed during the Mesozoic in ecological niches broadly similar to those of modern crocodiles, and some grew to very large sizes. At 6 meter in length, the Mid-Triassic Mastodonsaurus giganteus is not only thought to have been the largest capitosaur, but possibly also the largest amphibian to have lived. The latest known remains are from the Rhaetian of Germany and are referred to Cyclotosaurus.
