Aistopoda

Aistopoda (Greek for "[having] not-visible feet") is an order of highly specialised snake-like stegocephalians known from the Carboniferous and Early Permian of Europe and North America, ranging from tiny forms only , to nearly in length. They first appear in the fossil record in the Mississippian period and continue through to the Early Permian.

Ophiderpeton (from , 'snake' and 'creeper') is an extinct genus of aistopod tetrapodomorphs from the early Carboniferous to the early Permian. Remains of this genus are widespread and were found in Ohio, United States, Ireland, and the Czech Republic (Central Europe).

Phlegethontia is an extinct genus of aïstopod tetrapodomorphs from the Carboniferous and Permian periods of Europe and North America. upright|thumb|left|Early restoration of P. longissima

Oestocephalus is an extinct genus of aïstopod tetrapodomorphs that lived during the Carboniferous period. Fossils have been found in the Czech Republic, and in Ohio and Illinois in the United States. It is the type genus of the family Oestocephalidae, although it used to be assigned to the family Ophiderpetontidae, which is now considered paraphyletic. It was named by Edward Drinker Cope in 1868 and now contains two species, O. amphiuminus and O. nanum.

Pseudophlegethontia is an extinct genus of aïstopod tetrapodomorphs. It is the only member of the family Pseudophlegethontiidae. The only species is the type species P. turnbullorum, named in 2003. Fossils of Pseudophlegethontia have been found from the Mazon Creek fossil beds in Grundy County, Illinois, a conservation lagerstätte well known for the exceptional preservation of middle Pennsylvanian taxa.

Coloraderpeton is an extinct tetrapodomorph in the genus aïstopod within the family Oestocephalidae. Coloraderpeton is known from the Carboniferous Sangre de Cristo Formation of Colorado, and was initially known from vertebrae, ribs, and scales recovered from a UCLA field expedition in 1966. Peter Paul Vaughn described these remains in 1969. A skull was later reported in an unpublished 1983 thesis and formally described by Jason S. Anderson in 2003.

Oestocephalidae is an extinct family of Late Carboniferous aistopod tetrapodomorphs. Fossils have been found from Ohio, Illinois, and Colorado in the United States; England; and the Czech Republic. It includes the genera Coloraderpeton and Oestocephalus. Oestocephalids have robust skulls and narrow, rounded snouts. They possess heavily ossified gastralia and dorsal osteoderms. Like other aïstopods, oestocephalids were elongate, having approximately 110 vertebrae. Oestocephalidae was named in 2003, with the type species being Oestocephalus amphiuminus.

Phlegethontiidae is a family of extinct aistopod tetrapodomorphs including the genera Phlegethontia and Sillerpeton.

Lethiscus is the earliest known representative of the Aistopoda, a group of very specialised snake-like tetrapodomorphs known from the early Carboniferous (Mississippian).