A tetrapod is any four-limbed vertebrate animal of the superclass Tetrapoda. Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids and synapsids. Some tetrapods such as snakes, legless lizards, and caecilians had evolved to become limbless via mutations of the Hox gene, although some do still have a pair of vestigial spurs that are remnants of the hindlimbs.
"Labyrinthodontia" is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras. Traditionally considered a subclass of the class Amphibia, modern classification systems recognize that labyrinthodonts are not a formal natural group (clade) exclusive of other tetrapods. Instead, they consistute an evolutionary grade, ancestral to living tetrapods such as lissamphibians and amniotes. "Labyrinthodont"-grade vertebrates evolved from lobe-finned fishes in the Devonian, though a formal boundary between fish and amphibian is difficult to define at this point in time.
Temnospondyli or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent. A few species continued into the Jurassic and Early Cretaceous periods, but all had gone extinct by the Late Cretaceous. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including freshwater, 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 amphibians, many had characteristics such as scales and armour-like bony plates that distinguish them from the modern soft-bodied lissamphibians.
Hovasaurus is an extinct genus of basal diapsid reptile. It lived in what is now Madagascar during the Late Permian and Early Triassic, being a survivor of the Permian–Triassic extinction event and the paleontologically youngest member of the Tangasauridae. Fossils have been found in the Permian Lower and Triassic Middle Sakamena Formations of the Sakamena Group, where it is amongst the commonest fossils. Its morphology suggests an aquatic ecology.
Mastodonsaurus is an extinct genus of temnospondyl from the Middle Triassic of Europe. It belongs to a Triassic group of temnospondyls called Capitosauria, characterized by their large body size and presumably aquatic lifestyles. Mastodonsaurus remains one of the largest amphibians known, and may have exceeded 6 meters in length.
The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecological niche to modern crocodilians prior to the diversification of pseudosuchian archosaurs.
Archegosaurus is a genus of temnospondyl amphibian which lived during the Asselian to Wuchiapingian stages of the Permian, around 299-253 million years ago. The remains of this animal, consisting of at least 90 partial skeletons, have been found in Germany. The name Archegosaurus was coined by Goldfuss in 1847. Archegosaurus is a member of Archegosauridae and is that family's type genus.
Prionosuchus is an extinct genus of large temnospondyl. A single species P. plummeri, is recognized from the Early Permian. Its fossils have been found in what is now northeastern Brazil.
Platyoposaurus was a temnospondyl from the Middle Permian epoch about 270-268 Mya.
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.
Cheliderpeton is an extinct genus of temnospondyl amphibian. It lived during the Early Permian in what is now Europe. Fossils have been found from the Ruprechtice horizon of the Intrasudetic Basin of Bohemia in the Czech Republic, as well as the Saar-Nahe Basin of southwestern Germany. Cheliderpeton had a 16 cm skull, and reached about 65 cm in length.
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 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.
Konzhukovia is an amphibian genus that belongs to an extinct family Konzhukoviidae of temnospondyls, the largest clade of basal tetrapods including about 198 genera, 292 species, and more than half of which were alive during the early Mesozoic period. The animal was a predator that lived about 260 million years ago, and could get up to about three meters in length. Specifically, Konzukovia lived during the Permian, between 252 and 270 million years ago according to the type of rock the fossil was found in. There are three species within this genus, K. vetusta, K. tarda, and K. sangabrielensis, the first two originating from Russia while the latest originating from Southern Brazil. The discovery of this specimen in Southern Brazil provided more evidence to support the idea that during this animals existence, there was a “biological corridor” because of the supercontinent Pangea, allowing these species to be found so far apart from each other. Konzhukovia belongs to the family Archegosauridae, a family consisted of large temnospondyls that most likely compare to modern day crocodiles. Since the discovery of the latest species, K. sangabrielensis, Pacheco proposes that there must be the creation of a new family, Konzhokoviidae, a monophyletic group in a sister-group relationship with Stereospondlyi in order to accommodate the three species. Konzhukovia skulls usually exhibit typical rhinesuchid features including an overall parabolic shape, small orbits located more posteriorly, and the pterygoids do not reach the vomer. These animals were long-snouted amphibians that had clear adaptations made for fish catching, as well as exemplifying aquatic features.
Australerpeton is an extinct genus of stereospondylomorph temnospondyl currently believed to belong to the family Rhinesuchidae. When first named in 1998, the genus was placed within the new family Australerpetontidae. However, studies published a few years later questioned the systematics used in the original description and included the genus within Archegosauridae. A study by Dias & Schultz (2003) reassigned Australerpeton to the family Rhinesuchidae within the suborder Stereospondyli based on an earlier evaluation of the family. In this study, the close similarities between Australerpeton and archegosaurids were attributed to convergent evolution as a result of similar semi-aquatic lifestyles. A redescription of the skeleton of this genus was published by Eltink & Langer in 2014, and the skull was redescribed in a follow-up study published by Eltink et al. in 2016. These studies, as well as a 2017 study focusing on rhinesuchids in general, confirmed that Australerpeton was a rhinesuchid rather than an archegosaurid. Fossils of the genus have been found in the Rio do Rasto Formation of Brazil.
Nigerpeton is an extinct genus of crocodile-like temnospondyl amphibians from the late Permian (Changhsingian) period. These temnospondyls lived in modern-day Niger, which was once part of central Pangaea, about 250 million years ago. Nigerpeton is a member of the Cochleosauridae family, a group of edopoid temnospondyl amphibians known from the late Carboniferous (Pennsylvanian) and early Permian (Cisuralian).
Microposaurus is an extinct genus of trematosaurid temnospondyl. Fossils are known from the Cynognathus Assemblage Zone of the Beaufort Group in South Africa and the Rouse Hill Siltstone of Australia that date back to the Anisian stage of the Middle Triassic. These aquatic creatures were the short snouted lineage from Trematosaurinae.
Rhineceps is an extinct genus of temnospondyl amphibian in the family Rhinesuchidae. Rhineceps was found in Northern Malawi in Southern Africa known only from its type species R. nyasaensis. Rhineceps was a late Permian semi-aquatic carnivore that lived in streams, rivers, lakes or lagoons. Rhineceps is an early divergent Stereopondyl within the family Rhinesuchidae, which only existed in the late Permian (Lopingian) and failed to survive the Permian-Triassic extinction unlike other stereospondyl families.
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.
Melosaurinae is an extinct subfamily of temnospondyl amphibians, part of the family Archegosauridae. Most melosaurines are known from Russia, although an unnamed species has been found in Brazil. Unlike the long-skulled archegosaurids of the family Platyoposaurinae, melosaurines have shorter, broadened snouts.
Kashmirosaurus is an extinct genus of temnospondyl amphibian known from Permo-Carboniferous deposits in the region of Kashmir. It was originally named by English paleontologist Arthur Smith Woodward in 1905 as a species of Archegosaurus called Archegosaurus ornatus. More recently, the species has been recognized as being distinct from Archegosaurus, and it was placed in its own genus Kashmirosaurus in 1996. An additional species of Archegosaurus, A. kashmiriensis, was named in 1960 from the same deposits in Kashmir, and is now considered synonymous with Kashmirosaurus ornatus.
