It was a small animal at 22 cm snout-vent length, of generally lizard-like build and presumably habit.

The remains have been found in Nýřany, Czech Republic, dating from around 310 million years ago (upper Carboniferous).

[1] Originally thought to have been a seymouriamorph,[2] the phylogenetic position is uncertain, and now it is placed in the family Gephyrostegidae, together with the genus Bruktererpeton.

[8] Carroll (1970, 1972) states that while the skeleton of Gephyrostegus shows some adaptations for terrestrial life (e.g. in the specialization of the tarsus), it also retained some traits characteristic to aquatic non-amniote tetrapods, such the large size of the skull and the loose attachment of the vertebral elements, making it overall not as well adapted to the terrestrial environment as amniotes are.

According to Carroll, Gephyrostegus probably spent a large proportion of its adult life on land, but it may be assumed that it retained aquatic reproductive habits.