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.
Chondrostei is a group of non-neopterygian ray-finned fish. While the term originally referred to the paraphyletic grouping of all non-neopterygian ray-finned fish, it was redefined by Patterson in 1982 to be a clade comprising the Acipenseriformes and their extinct relatives.
Henri Marie Ducrotay de Blainville was a French zoologist and anatomist.
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.
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.
Pachycormus is an extinct genus of pachycormiform ray-finned fish known from the Early Jurassic of Europe.
Amblypterus is an extinct genus of freshwater ray-finned fish that lived during the Gzhelian and Cisuralian epoch in what is now Europe and possibly India and Argentina. Potential indeterminate records stretch as far back as the early Carboniferous.
Pycnodontiformes is an extinct order of primarily marine bony fish. The group first appeared during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America.
Asarotus is an extinct genus of prehistoric marine ray-finned fish from the Niobrara Formation of Nebraska, during the Campanian. The type species, A. arcanus is only known from poorly preserved single specimen, which makes hard to classify existing orders of Cretaceous actinopterygians. It is thus classified as the only member of its family Asarotidae and order Asarotiformes. Some authorities consider it a late-surviving member of the "palaeonisciform" fishes.
Ebenaqua is an extinct genus of bobasatraniiform bony fish that lived during the Lopingian epoch, of what is now Blackwater, Queensland, Australia. Fossils are found in the Rangal Coal Measures, which are Changhsingian in age. Its type and only species is Ebenaqua ritchiei.
Acrolepis is an extinct genus of prehistoric marine bony fish that lived from the Famennian stage of the Devonian to the early Triassic epoch. Some species from the Early Triassic of Tasmania are also ascribed to Acrolepis.
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.
Cosmoptychius is an extinct genus of freshwater and estuarine ray-finned fish that lived during the Mississippian epoch. It contains a single species, C. striatus from the Visean of Scotland. It has a wide stratigraphic range in the Wardie Shale, with many specimens known.
Saurocephalus is an extinct genus of ray-finned fishes within the family Saurodontidae. The genus was first described in 1824 and contains six or seven species, including the type species S. lanciformis. Saurocephalus first appeared during the early Valanginian and continued on to the Maastrichtian, where it nearly went extinct. However, the recent discovery of S. lanciformis remains from the earliest Paleocene indicates that it just barely survived into the Cenozoic. This would make it the last surviving ichthyodectiform.
Igornella is an extinct genus of prehistoric bony fish that lived during the Gzhelian (Stephanian) to Asselian ages in what is now France (Burgundy).
Saurorhynchus is an extinct genus of carnivorous bony fish that lived during the Early and Middle Jurassic epochs. Fossils have been found in Europe and North America (Canada). It is commonly found in pelagic and lagoonal deposits, but mostly marine. Largest specimens can grow up to 1.9 metres (6.2 ft).
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.
