Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest diverging group of living ray-finned fish after the bichirs. Despite being early diverging, they are highly derived, having only weakly ossified skeletons that are mostly made of cartilage, and in modern representatives highly modified skulls.
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.
Hypsocormus is an extinct genus of pachycormid fish from the Middle to Late Jurassic of Europe. Fossils have been found in Germany, France and the UK.
Prosqualodon is an extinct genus of Early to Middle Miocene cetacean from Argentina, Australia, New Zealand and Venezuela.
Tremacebus is an extinct genus of New World monkeys from the Early Miocene. The type species is T. harringtoni.
Gyrosteus is an extinct genus of very large ray-finned fish belonging to the family Chondrosteidae. It comprises the type species, Gyrosteus mirabilis, which lived during the early Toarcian in what is now northern Europe. A possible second species, "Gyrosteus" subdeltoideus, is known from otoliths.
Birgeria is a genus of carnivorous marine ray-finned fish from the Triassic period. Birgeria had a global distribution. Fossils were found in 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.
Watsonulus is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic epoch in what is now Madagascar. It may have also existed in what is now Himachal Pradesh, India, during the Induan age. The type species, described by Jean Piveteau, is Watsonia eugnathoides. Because "Watsonia" was preoccupied, the new genus name Watsonulus was later erected. The genus is named after David Meredith Seares Watson.
Helmolepis is an extinct genus of ray-finned fish that lived during the Early Triassic epoch in what is now Greenland, Madagascar and Canada. Species of Helmolepis are small. This genus is closely related with Platysiagum.
Stichopterus is an extinct genus of chondrostean ray-finned fish that lived during the Early Cretaceous epoch in Asia. It has been found in Russia and Mongolia.
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.
Parasemionotus is an extinct genus of prehistoric bony fish that lived in the Induan age of the Early Triassic epoch in what is now Madagascar. It is the name giving genus of the family Parasemionotidae and the order Parasemionotiformes.
Mioplosus is an extinct genus of percid fish that lived from the early to middle Eocene. Five species of the genus has been described, Mioplosus labracoides is found in the Green River Formation Lagerstätte. Mioplosus has numerous extant relatives in Northern Hemisphere fresh- and brackish water, as well as fossil relatives in Asia, Europe and New Zealand, and may be closely related to the modern-day pike-perches.
Trachymetopon is an extinct genus of prehistoric coelacanth from the Jurassic of Europe. Fossils have been found in the Early Jurassic Posidonia Shale of Germany the Middle Jurassic Marnes de Dives of France, and probably the Late Jurassic Kimmeridge Clay of England. Only one species has been named, Trachymetopon liassicum, described by Henning in 1951 from an almost complete specimen found in the Lower Toarcian of Ohmden in Baden-Württemberg. Another specimen is known from the same site, and two older specimens come from the Sinemurian of Holzmaden. The holotype of this species is 1.6 metres in length. A giant specimen of an undetermined species of Trachymetopon found at the Middle Jurassic Falaises des Vaches Noires of Normandy. This specimen, composed of a 53 cm long palatoquadrate, belongs to an individual 4 metres (13 ft) in length. A basisphenoid found in a museum in Switzerland that likely originates from the same locaity probably belonged to an individual around 5 m (16 ft) long, making Trachymetopon the largest of all coelacanths alongside Mawsonia. A study published in 2015 revealed that this coelacanth belongs to the Mawsoniidae. Trachymetopon is one of the few known mawsoniids to have been exclusively marine, while most of the other members of the group have lived in fresh and brackish waters.
Amiopsis is an extinct genus of prehistoric freshwater and marine bony fish belonging to the family Amiidae, making it closely related to the modern bowfin. Fossils are known from the Late Jurassic Solnhofen Limestone, Germany, the Early Cretaceous Purbeck Group, England, La Pedrera de Rúbies Formation, Spain and Bernnissant Iguanodon locality, Belgium and the Late Cretaceous (Cenomanian) of the Balkans. The monophyly of the genus is questionable, due to it being based on a single character, "the presence of three or more lateral fossae on each side of most abdominal centra". Remains previously assigned to this genus from the Early Cretaceous Las Hoyas, Spain have been moved into the new genus Hispanamia.
Orthocormus is an extinct genus of prehistoric pachycormiform bony fish. It is known from three species found in Late Jurassic (Kimmeridgian) aged plattenkalk deposits in Bavaria, Germany. The species "Hypsocormus" tenuirostris Woodward 1889 from the late Middle Jurassic (Callovian) Oxford Clay is not closely related to the type species of Hypsocormus, and is more closely related to Orthocormus + Protosphyraena, and thus has sometimes been referred to in open nomenclature as Orthocormus? tenuirostris. The species of Orthocormus reached over a metre in length, and are thought to have been pelagic predators.
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).
Peipiaosteus is an extinct genus of prehistoric chondrostean ray-finned fish. Its fossils are found in the Early Cretaceous Jiufotang Formation, Pani Lake, Liaoning Province, China.
Chondrosteidae is a family of extinct marine actinopterygian fishes in the order Acipenseriformes. Three genera are known from the Early Jurassic of Europe, Chondrosteus, Gyrosteus, and Strongylosteus. Included species were of large size, with body lengths ranging from 2 metres (6.6 ft) up to 7 metres (23 ft). Their skeleton was largely made up of bones, but ossification was reduced compared to other ray-fins.
Eochondrosteus is a genus of extinct actinopterygian, comprising one species, E. sinensis (monotypy) from the Early Triassic strata in Gansu Province, China. It is suggested to be the most basal acipenseriform. It was originally described in 2005, and then redescribed in 2020 in Chinese. Other authors have considered the placement of Eochondrosteus within the Acipenseriformes as tentative.
