Redfieldiiformes Temporal range: | |
---|---|
Dictyopyge macrurus from the Late Triassic of Virginia | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Subclass: | Neopterygii (?) |
Order: | † Redfieldiiformes Berg, 1940 |
Type genus | |
† Redfieldius Hay, 1899 | |
Families | |
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 (streamlined, tuna-like) 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 (thin spiny scales) fringing the fins, a reduced number of branchiostegal rays (typically just one), and a snout ornamented with tubercles. [1] [2] [3]
The maxilla has small teeth and is strongly connected to the preopercle; this would have allowed a deep gape to assist in ram feeding. [1] The function of the snout tubercles is uncertain; some authors have suggested that they attached to a fleshy upper lip, [2] while others argue that they could have held sensory organs akin to the tubercles of siluriforms (catfish). [3]
Redfieldiiforms were fairly primitive 'subholostean' fish (more primitive than holosteans such as gars or the bowfin), with uncertain relations to neopterygians. [1] Some studies draw comparisons to 'perleidiforms' or ptycholepids, while others consider redfieldiiforms to be early neopterygians related to pholidopleuriforms. [4] Redfieldiiforms were exclusively freshwater fish which became prominent in southern Gondwana (Argentina, Australia, southern Africa) during the Middle Triassic. [3] By the Late Triassic they had become a major component of freshwater ecosystems in western Laurasia (North America and Morocco). However, they were much rarer further east (South Korea, [3] possibly Switzerland [5] ). The last member of the order, Redfieldius , lived in the Early Jurassic of eastern North America. [1] [3]
The following families and genera are known:
The Amiiformes order of fish has only two extant species, the bowfins: Amia calva and Amia ocellicauda, the latter recognized as a separate species in 2022. These Amiiformes are found in the freshwater systems of North America, in the United States and parts of southern Canada. They live in freshwater streams, rivers, and swamps. The order first appeared in the Triassic, and the extinct members include both marine and freshwater species, many of which are morphologically disparate from bowfins, such as the caturids.
Dapedium is an extinct genus of primitive marine neopterygian ray-finned fish. The first-described finding was an example of D. politum, found in the Lower Lias of Lyme Regis, on the Jurassic Coast of England. Dapedium lived in the Late Triassic to the Middle Jurassic period, from the late Norian to the early Aalenian.
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.
Pachycormiformes is an extinct order of marine ray-finned fish known from the Early Jurassic to the end of the Cretaceous. It only includes a single family, Pachycormidae. They were characterized by having serrated pectoral fins, reduced pelvic fins and a bony rostrum. Pachycormiformes are morphologically diverse, containing both tuna and swordfish-like carnivorous forms, as well as edentulous suspension-feeding forms.
Daedalichthys is an extinct genus of prehistoric freshwater ray-finned fish that lived during the Early Triassic epoch. It contains a single species, D. formosa from the Olenekian-aged Cynognathus Assemblage Zone of South Africa. It was previously classified in Dictyopyge.
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.
Euthynotus is an extinct genus of prehistoric bony fish that lived during the early Toarcian stage of the Early Jurassic epoch. It is generally considered the basalmost pachycormiform.
Ainia is an extinct genus of prehistoric ray-finned fish that lived during the Kimmeridgian stage of the Late Jurassic epoch. It contains a single species, A. armata, known from the famous Solnhofen Limestone of Germany. It is a distant relative of the bowfin, although it is more closely related to genera such as Caturus and Osteorachis.
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.
Cyranorhis is an extinct genus of 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.
Ceramurus is an extinct genus of prehistoric marine ray-finned fish from the Late Jurassic. It contains a single species, C. macrocephalus from the Purbeck Group of England.
Guntherichthys is a genus of extinct ray-finned fish that lived during the late Mississippian/early Pennsylvanian in what is now Utah, United States. Fossils were recovered from the Manning Canyon Shale. The genus is named after Lloyd Gunther.
The Colorado City Formation is a Late Triassic geologic formation in the Dockum Group of Texas, United States. It has previously been known as the Iatan Member, Colorado City Member or 'Pre-Tecovas Horizon'.
Dorsetichthys is an extinct genus of marine stem-teleost ray-finned fish from the Early Jurassic period of Europe. It contains a single species, D. bechei, known from the Sinemurian-aged Lower Lias of England.
Ginglymodi is a clade of ray-finned fish containing modern-day gars (Lepisosteidae) and their extinct relatives in the order Lepisosteiformes, the extinct orders Semionotiformes and Kyphosichthyiformes, and various other extinct taxa. Ginglymodi is one of the two major subgroups of the infraclass Holostei, the other one being Halecomorphi, which contains the bowfin and eyespot bowfin and their fossil relatives.
Dapediidae is an extinct family of neopterygian ray-finned fish that lived from the Middle Triassic to Late Jurassic. It is the only family of the order Dapediiformes. Its members were historically placed within the ginglymodian family Semionotidae, but were moved to their own family in 1966, and subsequently to the separate order Dapediiformes in 2016.
Parasemionotiformes is an extinct order of neopterygian ray-finned fish that existed globally during the Triassic period. It comprises the families Parasemionotidae and Promecosominidae. Many of the included genera are monotypic and most species lived during the Early Triassic epoch.
Redfieldius is an extinct genus of freshwater ray-finned fish that inhabited eastern North America during the Early Jurassic period. It contains a single species, R. gracilis, known from the Hettangian to the Sinemurian of the northeastern United States. It is the type genus and was the last surviving member of the order Redfieldiiformes, which was widespread and diverse throughout the preceding Triassic period. It is notable for representing possibly the first fossil bony fish collected from North America, with a specimen from Middletown collected in 1816 by Benjamin Silliman.
Tanaocrossus is an extinct genus of primitive freshwater ray-finned fish that inhabited southwestern and eastern North America during the Late Triassic period. It contains a single known species, T. kalliokoskii, known from the United States, with indeterminate species also known.
Pacorichthys is an extinct genus of paleonisciform ray-finned fish from Switzerland. It is currently only known from the Meride Limestone, a part of the Monte San Giorgio palaeontological Lagerstatten, located in Canton Ticino. This deposit dates to the Middle Triassic, specifically the Late Ladinian. It was a small, fusiform fish similar to a large amount of other paleonisciformes though it possessed a expanded, fixed maxillary along with its suboperculum being larger than its operculum. Though not fitting with the paleoenvironments seen in the rest of the group, a Redfieldiiform affinity has been suggested for the genus. There is only a single species in the genus being P. sangiorgii.