Stegocephali

Ichthyostega, from Ancient Greek ἰχθύς (ikthús), meaning "fish", and στέγη (stégē), meaning "roof", is an extinct genus of limbed tetrapodomorphs from the Late Devonian of what is now Greenland. It was among the earliest four-limbed vertebrates ever in the fossil record and was one of the first with weight-bearing adaptations for terrestrial locomotion. Ichthyostega possessed lungs and limbs that helped it navigate through shallow water in swamps. Although Ichthyostega is often labelled a 'tetrapod' because of its limbs and fingers, it evolved long before true crown group tetrapods and could m

"Labyrinthodontia" (Greek, 'maze-toothed') is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras (about 390 to 150 million years ago). 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 (a paraphyletic group), ancestral to living tetrapods such as lissamphibians (modern amphibians) and amniotes (reptiles, mammals, and kin).

Acanthostega, from Ancient Greek ἄκανθα (ákantha), meaning "spine", and στέγη (stégē), meaning "roof", is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were able to come onto land.

Lepospondyli is a diverse grouping of early tetrapods. With the exception of one late-surviving lepospondyl from the Late Permian of Morocco (Diplocaulus minimus), lepospondyls lived from the Visean stage of the Early Carboniferous 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, sem

Hynerpeton ( ) is an extinct genus of early four-limbed vertebrate that lived in the rivers and ponds of Pennsylvania during the Late Devonian period, around 365 to 363 million years ago. The only known species of Hynerpeton is H. bassetti, named after the describer's grandfather, city planner Edward Bassett. Hynerpeton is known for being the first Devonian four-limbed vertebrate discovered in the United States, as well as possibly being one of the first to have lost internal (fish-like) gills.

Ichthyostegalia is an obsolete order of early amphibians, representing the earliest landliving vertebrates. The group is thus an evolutionary grade rather than a clade. While the group are recognized as having feet rather than fins, most, if not all, had internal gills in adulthood and lived primarily as shallow water fish and spent minimal time on land.

Anthracosauria is a paraphyletic order of extinct reptile-like amphibians (in the broad sense) that flourished during the Carboniferous and early Permian periods, although precisely which species are included depends on one's definition of the taxon. "Anthracosauria" is sometimes used to refer to all tetrapods more closely related to amniotes such as reptiles, mammals, and birds, than to lissamphibians such as frogs and salamanders. An equivalent term to this definition would be Reptiliomorpha. Anthracosauria has also been used to refer to a smaller group of large, crocodilian-like aquatic tet

Crassigyrinus (from , 'thick' and , 'tadpole') is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Clackmannan Group of Scotland and possibly Greer, West Virginia.

Elginerpeton is a genus of stegocephalian (stem-tetrapod), the fossils of which were recovered from Scat Craig, Morayshire in the UK, from rocks dating to the late Devonian Period (Late Frasnian stage, 375 million years ago). The type species is Elginerpeton pancheni.

Tulerpeton is an extinct genus of Devonian four-limbed vertebrate, known from a fossil that was found in the Tula Region of Russia at a site named Andreyevka. This genus, Acanthostega, and Ichthyostega represent the earliest tetrapods.

Ventastega (Venta referring to the Venta River at the Ketleri Formation where Ventastega was discovered) is an extinct genus of stem tetrapod that lived during the Upper Fammenian of the Late Devonian, approximately 372.2 to 358.9 million years ago. Only one species is known that belongs in the genus, Ventastega curonica, which was described in 1996 after fossils were discovered in 1933 and mistakenly associated with a fish called Polyplocodus wenjukovi. ‘Curonica’ in the species name refers to Curonia, the Latin name for Kurzeme, a region in western Latvia. Ventastega curonica was discovered

Whatcheeriidae is an extinct family of stem-tetrapods which lived in the Mississippian sub-period, a subdivision of the Carboniferous period. It contains the genera Pederpes, Whatcheeria, and possibly Ossinodus. Fossils of a possible whatcheeriid have been found from the Red Hill locality of Pennsylvania. If these remains are from a whatcheeriid, they extend the range of the family into the Late Devonian and suggest that advanced tetrapods may have lived alongside primitive tetrapod ancestors like Hynerpeton and Densignathus. They also imply that a very long ghost lineage of whatcheeriids live

Parmastega is an extinct genus of stem tetrapod from the Devonian, dated to the earliest Famennian age (about 372 million years ago), in contrast to later fossils known from late Famennian (365–359 million years ago). These later fossils are considerably younger, by about 30 million years, than the earliest recorded tetrapod footprints, which presented a mystery that Parmastega's more recently described morphology from a three dimensional reconstruction has helped provide insight on.

Whatcheeria is an extinct genus of early tetrapod from the Mississippian (Early Carboniferous) of Iowa. Fossils have been found in 340 million year old fissure fill deposits in the town of Delta. The type species, Whatcheeria deltae was named in 1995. It is classified within the family Whatcheeriidae, along with the closely related Pederpes and possibly Ossinodus.

Caerorhachis (meaning "suitable spine" in Greek) is an extinct genus of early tetrapod from the Early Carboniferous of Scotland, probably from the Serpukhovian stage. Its placement within Tetrapoda is uncertain, but it is generally regarded as a primitive member of the group. The type species C. bairdi was named in 1977.

Metaxygnathus is an extinct genus of ichthyostegalian found in Late Devonian deposits of New South Wales, Australia. It is known only from a lower jawbone. Previously thought to be a lobe-finned fish, it has now been reassigned to the earliest group of tetrapodomorphs.

Ymeria is an extinct genus of early stem tetrapod from the Devonian of Greenland. Of the two other genera of stem tetrapods from Greenland, Acanthostega and Ichthyostega, Ymeria is most closely related to Ichthyostega, though the single known specimen is smaller, the skull about 10 cm in length. A single interclavicle resembles that of Ichthyostega, an indication Ymeria may have resembled this genus in the post-cranial skeleton.

Gephyrostegidae is an extinct family of stegocephalian tetrapodomorphs from the Late Carboniferous including the genera Gephyrostegus, Bruktererpeton, and Eusauropleura. Gephyrostegus is from the Czech Republic, Brukterepeton is from Germany, and Eusauropleura is from the eastern United States.

Densignathus is an extinct genus of early stem-tetrapod from the Late Devonian-aged Catskill Formation of Pennsylvania in the United States. A lower jaw has been found from the Red Hill fossil site, which is known for a diversity of lobe-finned fishes and other early tetrapods like Hynerpeton. The type species, Densignathus rowei, was named in honor of paleontologist Norman Douglas Rowe in 2000.

Sinostega ("Chinese roof") is an extinct genus of early "tetrapod" from the Late Devonian of China.

Gaiasia is an extinct genus of stem-tetrapods from the Early Permian of Namibia, containing a single species, Gaiasia jennyae. Gaiasia was a freshwater predator which was exceptional among stem-tetrapods for its combination of relatively enormous size, Southern occurrence, and late survival.

Bruktererpeton is an extinct genus of gephyrostegid tetrapodomorph known from the Late Carboniferous of the Rhein-Ruhr-District, western Germany. It was first described and named by Jürgen A. Boy and Klaus Bandel in 1973 and the type species is Bruktererpeton fiebigi. Recent phylogenetic analyses confirmed that Bruktererpeton is a sister taxon of the better known genus Gephyrostegus.

Obruchevichthys is an extinct genus of stem-tetrapod from Latvia during the Late Devonian. When the jawbone, the only known fossil of this creature, was uncovered in Latvia, it was mistaken as a lobe-fin fish. However, when it was analyzed, it proved to hold many similarities to Elginerpeton, from Scotland. It was then declared belonging to the earliest group of tetrapods.

Jakubsonia is an extinct genus of early tetrapod from the Late Devonian of Russia. The type species, Jakubsonia livnensis, was described and named in 2004.

Tanyka () is an extinct genus of amphibious early stem-tetrapod known from the Early Permian (Kungurian age) Pedra de Fogo Formation of Brazil. The genus contains a single species, Tanyka amnicola, known from several mandibular remains. It is one of the few Gondwanan stem-tetrapods known to have survived into the Permian. The lower jaw is strongly twisted, with extensive fields of teeth, likely allowing it to process aquatic plants or small invertebrates.