Tanaocrossus Temporal range: | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Actinopterygii |
Order: | † Scanilepiformes |
Genus: | † Tanaocrossus Schaeffer, 1967 |
Species: | †T. kalliokoskii |
Binomial name | |
†Tanaocrossus kalliokoskii Schaeffer, 1967 | |
Tanaocrossus (Ancient Greek for "outstretched fringe", referring to its distinctive dorsal fin) 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. [1] [2]
It is primarily known from the Norian to Rhaetian of the Chinle Formation of Colorado and Utah. [3] [4] [5] Indeterminate remains are known from the Dockum Group of Texas and New Mexico (Bull Canyon Formation). [3] [6] A single fragmentary but distinctive fossilized fin from the earlier Carnian-aged Doswell Formation of Virginia, which shares the genus's distinctive fin rays, was long the only record from the eastern United States, but a partial specimen was also later identified from the Manassas Sandstone. [4] [6] [7]
Morphologically, it can be easily distinguished from other co-occurring fishes by its highly elongated dorsal fin that stretches across its body. Its taxonomic affiliations have long been enigmatic since its description due to its unusual morphology. [2] [7] [4] More recent studies have found it to be a scanilepiform, an enigmatic order of fish which were later found to most likely be basal cladistians, which would make it a distant relative of modern bichirs. [8] [9] A 2008 study questioned this assignment and instead reclassified it to the Perleidiformes, but this has been disputed by later studies. [10] [8] [11]
It was likely a slow-moving fish that inhabited quiet waters, with its dorsal fin allowing for undulation while swimming. [2]
Perleidus is an extinct genus of ray-finned fish from the Triassic period. Fossils have been found in the Middle Triassic of Italy, Switzerland, and China. The inclusion of Early Triassic species in the genus Perleidus was questioned.
Chinlea is an extinct genus of late Triassic Mawsoniid coelacanth fish found in and named after the Chinle Formation that crops out in the southwestern states of Arizona and New Mexico. The word “Chinle” comes from the Navajo word meaning "flowing out", referencing the location where water flows out of the Canyon de Chelly. They were also possibly found in the Dockum Group.
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.
Atopocephala is an extinct genus of prehistoric freshwater ray-finned fish that lived during the Middle Triassic epoch. It contains a single species, A. watsoni from the Karoo Supergroup of South Africa. A potential indeterminate species was known from the Timezgadiouine Formation of Morocco, but is now considered an indeterminate actinopterygian.
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.
Asialepidotus is an extinct genus of prehistoric marine ray-finned fish that lived during the Ladinian stage of the Middle Triassic epoch. It contains a single species, A. shingyiensis, from Guizhou, China.
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.
Luganoia is an extinct genus of prehistoric bony fish that lived during the Anisian and Ladinian ages of the Middle Triassic epoch. Fossils were recovered from the Besano Formation of Monte San Giorgio and Besano area and from the Zhuganpo Member of Guizhou, South China. It was also reported from the Ladinian of Spain.
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 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.
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.
Dandya is an extinct genus of marine ray-finned fish belonging to the family Dapediidae. It contains one species, D. ovalis. It is known from the Late Triassic-aged Zorzino Limestone of Lombardy, northern Italy and the Seefeld Formation of Austria.
Hemicalypterus is an extinct genus of prehistoric ray-finned fish that lived during the late Triassic period. It contains a single species, Hemicalypterus weiri. Fossils have been collected in the southwestern United States, including Utah and New Mexico. Hemicalypterus belonged to the family Dapediidae, and like other members of its family, it was a deep-bodied fish with a covering of thick ganoid scales. It differed from other dapediids in lacking scales on the posterior part of the body, and in possessing unusual, multicuspid teeth. These teeth were similar to those of modern-day herbivorous fish, which indicates that Hemicalypterus may have been a herbivore as well.
The Chinle Formation is an extensive geological unit in the southwestern United States, preserving a very diverse fauna of Late Triassic animals and plants. This is a list of fossilized organisms recovered from the formation.
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.
Beishanichthys is an extinct genus of freshwater ray-finned fish which existed in Gansu Province, China during the Olenekian age of the early Triassic period. It contains a single species, B. brevicaudalis, first named by Guang-Hui Xu, Ke-Qin Gao in 2011 based on fossils from the Lower Triassic lake deposits exposed in Beishan area. It is considered a scanilepiform, a group of early cladistians related to the modern bichirs, although Beishanichthys was not incorporated into the analyses that found this phylogenetic placement among the cladistians.
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'.
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.
Turseodus is an extinct genus of ray-finned fish found in Late Triassic freshwater sediments of the United States. Two species have been described, T. acutus from the Lockatong Formation of Pennsylvania, and T. dolorensis from the Chinle Formation of Colorado.
Cionichthys is an extinct genus of freshwater ray-finned fish that inhabited southwestern and eastern North America during the Late Triassic period. It was a member of the Redfieldiiformes, an order of fishes widespread throughout freshwater habitats at this time, especially in North America.