Tristichopterids (Tristichopteridae) were a diverse and successful group of fish-like tetrapodomorphs living throughout the Middle and Late Devonian.

Some tristichopterids share some of the features of the elpistostegalians, a diverse clade of tetrapodomorphs close to the origin of (and including) tetrapods.

In the skeleton of the front fins, which were deeply attached, the elements of the forelimb of the later tetrapodomorphs, such as the humerus, ulna and radius, can already be recognized.

[6] Eusthenopteron differs significantly from some later Carboniferous tetrapods in the apparent absence of a recognized larval stage and a definitive metamorphosis.

In even the smallest known specimen of Eusthenopteron foordi (at 29 mm), the lepidotrichia cover all of the fins, which does not happen until after metamorphosis in genera like Polyodon.

[9] More genera would later be placed in Eusthenopteridae, with Vorobyeva and Obruchev (1964) stating Eusthenodon and possibly Platycephalichthys are members of this family, while Carroll (1988) added Hyneria and tentatively assigned Devonosteus and Litoptychus to the group.

Here, Platycephalichthys is not considered a member of the Tristichopteridae:[1] Spodichthys Tristichopterus Eusthenopteron Jarvikina Cabonnichthys Mandageria Eusthenodon