Colosteidae is a family of stegocephalians that lived in the Carboniferous period. They possessed a variety of characteristics from different tetrapod or stem-tetrapod groups, which made them historically difficult to classify. They are now considered to be part of a lineage intermediate between the earliest Devonian terrestrial vertebrates, and the different groups ancestral to all modern tetrapods, such as temnospondyls and reptiliomorphs.

Stegocephali is a clade of vertebrate animals containing all fully limbed tetrapodomorphs. It is equivalent to a broad definition of the superclass Tetrapoda: under this broad definition, the term "tetrapod" applies to any animal descended from the first vertebrate with four limbs each with five digits in the extremity (pentadactyly), rather than fins of their sarcopterygian relatives.