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Xenacanth
Xenacanthida (or Xenacanthiformes) is an order or superorder of extinct shark-like chondrichthyans (cartilaginous fish) known from the Carboniferous to Triassic. They were native to freshwater, marginal marine and shallow marine habitats. Some xenacanths may have grown to lengths of . Most xenacanths died out at the end of the Permian in the End-Permian Mass Extinction, with only a few forms surviving into the Triassic. Description The foundation of the tooth is prolonged lingually with a circlet button and a basal tubercle on the oral and aboral surfaces individually. The family Xenacanthidae consists of five genera: ''Xenacanthus'', ''Triodus'', ''Plicatodus'', '' Mooreodontus'' and '' Wurdigneria''; all of these are distinguished by cross sections of the points, crown center, length of the median edge, type of vertical cristae, and microscopic anatomy. Xenacanths are divided into two groups based on dental characteristics. Group one has tricuspid crowns containing two stout, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenacanthida
Xenacanthida (or Xenacanthiformes) is an order or superorder of extinct shark-like chondrichthyans (cartilaginous fish) known from the Carboniferous to Triassic. They were native to freshwater, marginal marine and shallow marine habitats. Some xenacanths may have grown to lengths of . Most xenacanths died out at the end of the Permian in the End-Permian Mass Extinction, with only a few forms surviving into the Triassic. Description The foundation of the tooth is prolonged lingually with a circlet button and a basal tubercle on the oral and aboral surfaces individually. The family Xenacanthidae consists of five genera: ''Xenacanthus'', '' Triodus'', '' Plicatodus'', '' Mooreodontus'' and '' Wurdigneria''; all of these are distinguished by cross sections of the points, crown center, length of the median edge, type of vertical cristae, and microscopic anatomy. Xenacanths are divided into two groups based on dental characteristics. Group one has tricuspid crowns containing two sto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenacanthus
''Xenacanthus'' (from Ancient Greek wikt:ξένος, ξένος, xénos, 'foreign, alien' + wikt:ἄκανθος, ἄκανθος, akanthos, 'spine') is an extinct genus of Xenacanthida, xenacanth cartilaginous fish. It lived in freshwater environments, and fossils of various species have been found worldwide. Description ''Xenacanthus'' is a relatively small member of its order. ''X. decheni'' reached about , ''X. meisenheimensis'' reached up to , ''X''. (''Expleuracanthus'') ''gaudryi'' reached . ''X. parallelus'' is one of the smallest xenacanths, males reached and females reached , both are fully grown. The dorsal fin was ribbonlike and ran the entire length of the back and round the tail, where it joined with the anal fin. This arrangement resembles that of modern conger eels, and ''Xenacanthus'' probably swam in a similar manner. A distinctive spine projected from the back of the head and gave the genus its name. The spike has even been speculated to have been venomous, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barbclabornia
''Barbclabornia'' is an extinct genus of xenacanth from the Early Permian and possibly upper Pennsylvanian of North America. The genus contains a single described species: ''B. luedersensis''. It has been found in several places within Asselian and Atinskian formations, including the Clear Fork, Albany, Wichita, and Dunkard Groups. There are possible examples from the Gzhelian-aged Admire, Monongahela, and Conemaugh groups. Discovery ''Barbclabornia'' was initially only known from isolated teeth, which were assigned to the genus ''Xenacanthus'' in 1970 based on the belief that all Upper Paleozoic xenacanthids belonged to said genus. In 2003, ''X. luedersensis'' would be reassigned to a new genus after differences in tooth structure were described, and with the discovery of a large palatoquadrate bearing ''luedersensis'' teeth at Lake Frederick. The genus ''Barbclabornia'' honors Barbara and Alvie Claborn, who discovered and helped prepare the palatoquadrate respe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrichthyes
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opercula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. The class is divided into two subclasses: Elasmobranchii (sharks, rays, skates and sawfish) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class). Extant chondrichthyans range in size from the finless sleeper ray to the over whale shark. Anatomy Skeleton The skeleton is cartilaginous. The notochord is gradually replaced by a vertebral column during development, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lebachacanthus
''Lebachacanthus'' is a genus of extinct xenacanth cartilaginous fish known from the late Carboniferous-Early Permian of Europe. Well-preserved specimens, originally identified as '' Orthacanthus'', are known from Meisenheim Formation in Germany. During the late Paleozoic, xenacanths were the apex predators of freshwater ecosystems, preying on small amphibians. Description Like most other xenacanthids, this genus possessed an array of spines arising from the dorsal fins. It exceeded and even could reach . The genus is often confused with the similar genus '' Orthacanthus''; the two genera belong to entirely separate families. The teeth of this fish were multi-cusped, with the central cusp flanked by two sharp accessory "tines" on which its prey would be impaled and trapped, in preparation for being swallowed whole. It had an abundance of pectoral fins, two next to the head, two in the middle, one near the end, and one under the caudal fin. Paleobiology ''Lebachacanthus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bransonella
''Bransonella'' is an extinct genus of marine xenacanth which lived during the Paleozoic era. It is known only from teeth which are easily distinguished from related genera by ornamentation on the cusp shaped like an inverted "V" and fin spines Teeth attributed to this genus are small, no greater than 2 millimeters. This suggests a small body size likely not exceeding a meter in length. It has been suggested their lifestyle was similar to modern Catsharks. It was used to erect a new order along with '' Barbclabornia'' based on ornamentation. There are four species currently attributed to this genus. The first species described was ''B. tridentata'' in 1933, which was erroneously identified as a conodont. ''B. nebraskensis'' was described from the late Pennsylvanian of Nebraska and later recognized from the middle Mississippian to the early Permian of Kansas, the Urals, Poland, Belgium, Russia, and England. ''B. lingulata'' is known from Serpukhovian of Russia. ''B. tribula'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triodus Teberdaensis
''Triodus'' is an extinct genus of xenacanthiform cartilaginous fish that lived from the Carboniferous to the Permian. In 2017, a new species ''Triodus richterae'' was described from the Rio do Rasto Formation of Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population .... References Further reading * ''The Rise of Fishes: 500 Million Years of Evolution'' by John A. Long Xenacanths Prehistoric cartilaginous fish genera Carboniferous cartilaginous fish Permian cartilaginous fish Prehistoric fish of North America Carboniferous United States Permian United States Prehistoric fish of South America Permian Brazil Fossils of Brazil Paraná Basin Fossil taxa described in 1849 {{Paleo-cartilaginous-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triodus
''Triodus'' is an extinct genus of xenacanthiform cartilaginous fish that lived from the Carboniferous to the Permian. In 2017, a new species ''Triodus richterae'' was described from the Rio do Rasto Formation of Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population .... References Further reading * ''The Rise of Fishes: 500 Million Years of Evolution'' by John A. Long Xenacanths Prehistoric cartilaginous fish genera Carboniferous cartilaginous fish Permian cartilaginous fish Prehistoric fish of North America Carboniferous United States Permian United States Prehistoric fish of South America Permian Brazil Fossils of Brazil Paraná Basin Fossil taxa described in 1849 {{Paleo-cartilaginous-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plicatodus
''Plicatodus'' is a prehistoric cartilaginous fish in the family Xenacanthidae that lived in Europe during the late Carboniferous and Early Permian Periods. It was described by Oliver Hampe in 1995, and the type species is ''Plicatodus jordani''. The type locality for this genus is the Saar-Nahe basin.Plicatodus jordani n. g., n. sp., a new xenacanthid shark from the Lower Permian of Europe (Saar-Nahe Basin, Germany) by Oliver Hampe, 1995. Description ''Plicatodus'' fossil ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphycercal
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only by muscles. Fish fins are distinctive anatomical features with varying structures among different clades: in ray-finned fish (Actinopterygii), fins are mainly composed of bony spines or rays covered by a thin stretch of scaleless skin; in lobe-finned fish (Sarcopterygii) such as coelacanths and lungfish, fins are short rays based around a muscular central bud supported by jointed bones; in cartilaginous fish (Chondrichthyes) and jawless fish (Agnatha), fins are fleshy " flippers" supported by a cartilaginous skeleton. Fins at different locations of the fish body serve different purposes, and are divided into two groups: the midsagittal ''unpaired fins'' and the more laterally located ''paired fins''. Unpaired fins are predominantly as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Case (Chondrichthyes)
An egg case or egg capsule, often colloquially called a mermaid's purse, is the casing that surrounds the eggs of oviparous chondrichthyans. Living chondricthyans that produce egg cases include some sharks, skates and chimaeras. Egg cases typically contain one embryo, except for big skate and mottled skate egg cases, which contain up to 7 embryos. Oviparity is completely absent in the superorder Squalomorphi. Egg cases are also thought to have been produced by some extinct chondrichthyan groups, such as hybodonts and xenacanths. Description Egg cases are made of collagen protein strands, and are often described as feeling rough and leathery. Some egg cases have a fibrous material covering the outside of the egg case, thought to aid in attachment to substrate. Egg cases without a fibrous outer layer can be striated, bumpy, or smooth and glossy. With the exception of bullhead shark eggs, egg cases are typically rectangular in shape with projections, called horns, at eac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian
The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the sixth and last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the Perm Governorate, region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the Sauropsida, sauropsids (reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
