''Discoserra'' ("serrated disc") is a prehistoric

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

from the Mississippian of the

Bear Gulch Limestone The Bear Gulch Limestone is a limestone-rich Lens (geology), geological lens in central Montana, renowned for the quality of its marine fossils from the late Mississippian (geology), Mississippian subperiod, about 324 million years ago. It is expo ...

in Montana. It is a member of the

Guildayichthyiformes Guildayichthyidae is a prehistoric family of marine fish from the Mississippian Bear Gulch Limestone of Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It ...

with a round body and a skull possessing primitive and modern traits. ''Discoserra'' is about 60 mm long. In 2006, ''Discoserra'' was hypothesized to be a

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

neopterygian, although it has alternatively been placed in

Cladistia Cladistia is a subclass of bony fishes whose only living members are the bichirs of tropical Africa. Their major synapomorphies are a heterocercal tail in which the dorsal fin has independent rays, and a posteriorly elongated parasphenoid. ...

along with other Guildayichthyiformes.

References

Guildayichthyiformes Mississippian ray-finned fish of North America {{paleo-rayfinned-fish-stub