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 skin supported by radially extended thin bony spines called lepidotrichia, as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii. Resembling folding fans, the actinopterygian fins can easily change shape and wetted area, providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton.
Cheirolepis is an extinct genus of marine and freshwater ray-finned fish that lived in the Devonian period of Europe and North America. It is the only genus yet known within the family Cheirolepididae and the order Cheirolepidiformes. It was among the most basal of the Devonian actinopterygians and is considered the first to possess the "standard" dermal cranial bones seen in later actinopterygians.
Saurichthys is an extinct genus of predatory ray-finned fish from the Triassic Period. It is the type genus of the family Saurichthyidae, and the most speciose and longest lasting genus in the family. This family also includes the Permian Eosaurichthys (China) and the Jurassic Saurorhynchus from Europe and North America, though it may be more appropriate to treat these as subgenera of Saurichthys, due to the genus Saurichthys otherwise being paraphyletic.
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.
Birgeria is a genus of carnivorous marine ray-finned fish from the Triassic period. Birgeria had a global distribution, with fossil known from Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland. Birgeria existed throughout the entire Triassic period, from the very beginning just after the Permian-Triassic mass extinction, up to the very end with its extinction during the Triassic-Jurassic mass extinction.
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.
Eosaurichthys is an extinct genus of saurichthyid ray-finned fish that lived during the late Permian epoch in what is now China.
Cornuboniscus is an extinct genus of prehistoric 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.
Cheirodopsis is an extinct genus of marine ray-finned fish that lived during the Viséan stage of the Mississippian epoch. It contains a single species, C. geikiei from what is now Glencartholm, Scotland.
Ctenognathichthys is an extinct genus of prehistoric marine ray-finned fish that lived during the Middle Triassic epoch of Europe, in the former Tethys Ocean.
Acentrophorus is an extinct genus of prehistoric freshwater and marine ray-finned fish from the Roadian to the Wuchiapingian of England, Germany (Kupferschiefer), Italy and Russia. There may also be a Triassic occurrence in Australia.
Cyranorhis is an extinct genus of prehistoric marine ray-finned fish that lived during the Serpukhovian age of the Carboniferous period. One species is known, C. bergeraci in the Bear Gulch Limestone what is now Montana, United States. It is named after French novelist Cyrano de Bergerac.
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.
Cretatriacanthus is an extinct genus of prehistoric marine ray-finned fish from the Late Cretaceous. It contains a single species, C. guidottii from the late Campanian or early Maastrichtian of Nardò, Italy. It is generally placed as a basal tetraodontiform, although more recent studies have disputed this, finding it to instead represent an early basal percomorph.
Decazella is an extinct genus of prehistoric 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.
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.
Redfieldiiformes is an extinct order of ray-finned fish (actinopterygians) which lived from the Early Triassic to Early Jurassic. Redfieldiiforms were fairly typical Triassic fish in overall anatomy. They had a fusiform body shape with thick, ganoine-covered scales. The dorsal and anal fins were large, positioned opposite from each other, and shifted back, close to the tail. The caudal fin was hemiheterocercal, with the vertebral column and body scales extending into an upper lobe equal in size and shape to the lower lobe. They also had several characteristic skeletal traits, such as a hatchet-shaped preopercle, a series of fulcra fringing the fins, a reduced number of branchiostegal rays, and a snout ornamented with tubercles.
Tanyrhinichthys is an extinct genus of prehistoric ray-finned fish with a lengthened rostrum that lived during the Kasimovian (Missourian) age in what is now New Mexico, United States. Fossils were recovered from Tinajas Member of the Atrasado Formation.
Coccocephalus is an extinct genus of prehistoric freshwater and marine basal ray-finned fish from the Carboniferous to the early Permian period. The type species, C. wildi, lived during the Bashkirian age of the Pennsylvanian epoch in what is now Lancashire, United Kingdom. One specimen of C. wildi is notable for having the earliest known instance of fossilized brain tissue in a vertebrate.
