The Bear Gulch Limestone is a limestone-rich geological lens in central Montana, renowned for the quality of its late Mississippian-aged fossils. It is exposed over a number of outcrops northeast of the Big Snowy Mountains, and is often considered a component of the more widespread Heath Formation. The Bear Gulch Limestone reconstructs a diverse, though isolated, marine ecosystem which developed near the end of the Serpukhovian age. It is a lagerstätte, a particular type of rock unit with exceptional fossil preservation of both articulated skeletons and soft tissues. Bear Gulch fossils include a variety of fish, invertebrates, and algae occupying a number of different habitats within a preserved shallow bay.
Falcatus is an extinct genus of falcatid chondrichthyan which lived during the early Carboniferous Period in Bear Gulch bay in what is now Montana.
Stethacanthidae is an extinct family of prehistoric holocephalians. It is estimated to have existed approximately between 380 and 300 million years ago. Members of this family are noted for their peculiar dorsal fin.
The Palaeonisciformes, commonly known as "palaeoniscoids" are an extinct grouping of primitive ray-finned fish (Actinopterygii), spanning from the Silurian/Devonian to the Cretaceous. They are generally considered paraphyletic, but their exact relationships to living ray-finned fish are uncertain. While some and perhaps most palaeoniscoids likely belong to the stem-group of Actinopteryii, it has been suggested that some may belong to the crown group, with some of these possibly related to Cladistia and/or Chondrostei. Many palaeoniscoids share a conservative body shape and a similar arrangement of skull bones, though paleoniscoids as a whole exhibit considerable diversity in body shape.
Dicellopyge is an extinct genus of freshwater ray-finned fish that lived during the early Anisian age of the Middle Triassic epoch in what is now South Africa. It was originally named "Dicellopygae" by James Brough but the name was later corrected to Dicellopyge by Peter Hutchinson.
Pteronisculus is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic and Middle Triassic epochs of the Triassic period worldwide.
Cornuboniscus is an extinct genus of freshwater ray-finned fish that lived during the Pennsylvanian epoch (Carboniferous), and the only member of the family Cornuboniscidae. It contains a single species, C. budensis from the Bashkirian/lower Westphalian age of what is now Cornwall, England. The genus Cornubonisus was named after the island of Cornubian, and the species name refers to the coastal town of Bude in Cornwall. The type specimen is held in the town's Castle Heritage Centre.
Styracopterus is an extinct genus of ray-finned fish that lived during the Tournaisian stage of the Mississippian epoch of Scotland and Eastern European Platform, Russia.
Nematoptychius is an extinct genus of ray-finned fish that lived from the Visean age of the Mississippian epoch to the Bashkirian age of the Pennsylvanian epoch in what is now Scotland, Belgium and France.
Watsonichthys is an extinct genus of ray-finned fish that lived during the Tournaisian age to possibly the Asselian age in what is now Europe and possibly Namibia. It is named after David Meredith Seares Watson.
Scanilepis is an extinct genus of prehistoric bony fish that lived during the Rhaetian-?Hettangian ages. The type species, S. dubia, is known from the Rhaetian freshwater deposits of the Bjuv member of the Höganäs Formation, southwestern Sweden. A second species, S. spitzbergensis was mentioned from the Hettangian of the Festning section of the Grøfjorden area in Spitsbergen, Norway but was never described.
Cycloptychius is an extinct genus of prehistoric freshwater & marine ray-finned fish that existed throughout much of the Carboniferous period in Eurasia, and possibly into the Early Permian in South Africa. It was a member of the Rhadinichthyidae, a family of basal ray-finned fish that was formerly placed in the now-paraphyletic order Palaeonisciformes.
Cosmolepis is an extinct genus of prehistoric marine ray-finned fish that lived during the Early Jurassic epoch. It contains a single species, C. ornatus from the Blue Lias in what is now England. It is the only member of the family Cosmolepididae.
Decazella is an extinct genus of freshwater ray-finned fish that lived during the late Carboniferous period. It contains a single species, D. vetteri from the Gzhelian (Stephanian) age of what is now Occitania, France.
Phanerosteon is an extinct genus of ray-finned fish from the Carboniferous period. The type species, P. mirabile, was recovered from the Calciferous sandstone series (Pennsylvanian), Scotland. A second species, P. phonax was described from the Serpukhovian aged Bear Gulch Limestone lagerstätte in Montana, United States.
Cladistia is a clade 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.
Bourbonnella is an extinct genus of prehistoric freshwater and coastal marine ray-finned fish that lived during the late Mississippian (Carboniferous) and Asselian in what is now Burgundy, the Czech Republik, and Utah, with other remains known from elsewhere. The genus was named by Daniel Heyler in 1967.
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.
Discoserra is a prehistoric ray-finned fish from the Mississippian of the Bear Gulch Limestone in Montana. It is a member of the Guildayichthyiformes 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 neopterygian, although it has alternatively been placed in Cladistia along with other Guildayichthyiformes.
Pygopterus is an extinct genus of prehistoric bony fish that lived during the Wuchiapingian to Olenekian ages in what is now England, Germany, Greenland and Svalbard (Spitsbergen). It is one of the few genera of ray-finned fish known to cross the Permian-Triassic boundary.
