See text Guildayichthyidae is a prehistoric family of marine fish from the Mississippian Bear Gulch Limestone of Montana.

[1][2] It is the only family in the order Guildayichthyiformes.

Guildayichthyids possess an uncommon mixture of primitive and modern characteristics in their skull bones.

[3] This family consists of the following genera and species:[1]

This article about a prehistoric ray-finned fish is a stub.