Guildayichthyidae
Guildayichthyidae is a prehistoric family of marine fish from the Mississippian Bear Gulch Limestone of Montana. It is the only family in the order Guildayichthyiformes. Guildayichthyids possess an uncommon mixture of primitive and modern characteristics in their skull bones.
Their taxonomy has long been debated, with studies placing them within the Neopterygii, while others placed them within the Cladistia. A 2025 study found them to most likely be the sister group to the extinct Bobasatraniiformes, with the two forming an early-diverging clade within the crown group Actinopterygii.
Taxonomy
This family consists of the following genera and species:- Genus Guildayichthys Lund, 2000
- * Species Guildayichthys carnegiei Lund, 2000
- Genus Discoserra Lund, 2000
- * Species Discoserra pectinodon Lund, 2000