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Cow Shark
Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its 37 species are placed within the 10 genera: ''Gladioserratus'', ''Heptranchias'', ''Hexanchus'', ''Notidanodon'', ''Notorynchus'', ''Pachyhexanchus'', ''Paraheptranchias'', ''Pseudonotidanus'', ''Welcommia'', and ''Weltonia''.Compagno, L., Dando, M. and Fowler, S. ''Sharks of the World''. Princeton Field Guides Cow sharks are considered the most primitive of all the sharks, as their skeletons resemble those of ancient extinct forms, with few modern adaptations. Their excretory and digestive systems are also unspecialized, suggesting they may resemble those of primitive shark ancestors. A possible hexanchid tooth is known from the Permian of Japan, making the family a possible extant survivor of the Permian-Triassic extinction. Their most distinctive feature, however, is the presence of a sixth, and, in two genera, a seventh, gill slit, in contrast to the five found in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian
The Permian ( ) is a geologic period and 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 251.9 Mya. It is the 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 region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the 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 drier conditions, rose to dominance in place of their am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gladioserratus Dentatus
''Gladioserratus'' is an extinct genus of cow shark. It contains three species: *''Gladioserratus aptiensis'' Pictet, 1865 *''Gladioserratus magnus'' Underwood, Goswami, Prasad, Verma & Flynn, 2011 *'' Gladioserratus dentatus'' Guinot, Cappetta & Adnet, 2014 The authors of its description considered it to be an exclusively Cretaceous genus, containing species living from Hauterivian to Cenomanian. Subsequently the species ''G. dentatus'' was described from the Valanginian of France. Teeth described by Adolfssen and Ward (2015), collected from the middle Danian Faxe Formation at Faxe, Denmark, extend the temporal range of the genus to Paleocene; according to the authors, the species ''"Notorynchus" serratissimus'' Agassiz (1843) should probably be assigned to the genus ''Gladioserratus'' as well, which, if confirmed, would further extended the temporal range of the genus to the early Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 millio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Sixgill Shark
The Atlantic sixgill shark (''Hexanchus vitulus'') is a rare species of hexanchid shark found in the Atlantic Ocean. It was formerly described as its own species, but was synonymised with the bigeye sixgill shark The bigeyed sixgill shark (''Hexanchus nakamurai'') is a cow shark of the family Hexanchidae. Its dorsal surface has a brownish-gray color, and is sharply separated from the light coloring of its ventral surface. The eyes are a fluorescent gree ... (''Hexanchus nakamurai''). However, a study published in 2019 resurrected the species on the basis of molecular data. The species can be physically differentiated from the bluntnose sixgill shark (''Hexanchus griseus'') by its much smaller size and position of the dorsal fin in relation to the caudal fin. The Atlantic sixgill shark (''Hexanchus vitulus'') becomes sexually mature at around 1.40 to 1.75 meters. They do not reach lengths much greater than 180 cm. Springer, S., & Waller, R. A. (1969). Hexanchus vitulus, a new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bigeye Sixgill Shark
The bigeyed sixgill shark (''Hexanchus nakamurai'') is a cow shark of the family Hexanchidae. Its dorsal surface has a brownish-gray color, and is sharply separated from the light coloring of its ventral surface. The eyes are a fluorescent green while the shark is alive. The body of this shark is small, slim, and fusiform in shape. As the name suggests, this shark has six gill slits, unusual among most shark species. The head is narrow and somewhat flattened, and the mouth contains 5 rows of large, comb-shaped teeth. This shark's single dorsal fin is pushed back towards the caudal fin, and is behind the pelvic fins. The upper caudal fin is much longer than the lower, with a deep notch near the tip. All fins have thin white margins on the edge. In juveniles, the upper caudal fin has a black tip. Measurements Length at birth for this species is 34–45 cm; adults average 1.2 m for both genders, with a maximum of 1.8 m. Mature adults weigh around 20 kg. Range and habitat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bluntnose Sixgill Shark
The bluntnose sixgill shark (''Hexanchus griseus''), often simply called the cow shark, is the largest hexanchoid shark, growing to in length. It is found in tropical and temperate waters worldwide and its diet is widely varied by region. The bluntnose sixgill is a species of sixgill sharks, of genus ''Hexanchus'', a genus that also consists of two other species: the bigeye sixgill shark ( ''Hexanchus nakamurai'') and the Atlantic sixgill shark ( ''Hexanchus vitulus''). Through their base pairs of mitochondrial genes COI and ND2, these three species of sixgills widely differ from one another. Taxonomy The first scientific description of the bluntnose sixgill shark was authored in 1788 by Pierre Joseph Bonnaterre. As a member of the family Hexanchidae, it has more close relatives in the fossil record than living relatives. The related living species include the dogfish, the Greenland shark, and other six- and seven-gilled sharks. Some of the shark's relatives date back 200 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptranchias Tenuidens
''Heptranchias'' is a genus of sharks in the family Hexanchidae. Species *'' Heptranchias perlo'' ( Bonnaterre, 1788) (sharpnose sevengill shark) *†'' Heptranchias ezoensis'' Applegate & Uyeno, 1968 *†'' Heptranchias howelli'' Reed, 1946 *†'' Heptranchias karagalensis'' Kozlov in Zhelezko & Kozlov, 1999 *†'' Heptranchias tenuidens'' Leriche, 1938 Fossil record Fossils of ''Heptranchias'' are found in marine strata from the Cretaceous period. Fossils are known from various localities in Europe, North America, South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ..., New Zealand and Japan. Bibliography *Bonnaterre, J.P. 1788, Tableau encyclopédique et méthodique des trois règnes de la nature... Ichthyologie. Paris. Tableau encyclopédique et méthodique d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptranchias Karagalensis
''Heptranchias'' is a genus of sharks in the family Hexanchidae. Species *'' Heptranchias perlo'' ( Bonnaterre, 1788) (sharpnose sevengill shark) *†'' Heptranchias ezoensis'' Applegate & Uyeno, 1968 *†'' Heptranchias howelli'' Reed, 1946 *†'' Heptranchias karagalensis'' Kozlov in Zhelezko & Kozlov, 1999 *†''Heptranchias tenuidens'' Leriche, 1938 Fossil record Fossils of ''Heptranchias'' are found in marine strata from the Cretaceous period. Fossils are known from various localities in Europe, North America, South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ..., New Zealand and Japan. Bibliography *Bonnaterre, J.P. 1788, Tableau encyclopédique et méthodique des trois règnes de la nature... Ichthyologie. Paris. Tableau encyclopédique et méthodique de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptranchias Howelli
''Heptranchias howelli'', the sevengill shark, is a nektonic carnivore in the genus ''Heptranchias''. It is an extinct species that ranged from 37.2 to 20.43 Ma.''Heptranchias howelli'' at Fossilworks.org Fossil record Teeth from ''Heptranchias howelli'' have been found in Europe. An antero-lateral tooth and an upper lateral tooth were found in , |
Heptranchias Ezoensis
''Heptranchias'' is a genus of sharks in the family Hexanchidae. Species *'' Heptranchias perlo'' ( Bonnaterre, 1788) (sharpnose sevengill shark) *†'' Heptranchias ezoensis'' Applegate & Uyeno, 1968 *†''Heptranchias howelli'' Reed, 1946 *†''Heptranchias karagalensis'' Kozlov in Zhelezko & Kozlov, 1999 *†''Heptranchias tenuidens'' Leriche, 1938 Fossil record Fossils of ''Heptranchias'' are found in marine strata from the Cretaceous period. Fossils are known from various localities in Europe, North America, South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ..., New Zealand and Japan. Bibliography *Bonnaterre, J.P. 1788, Tableau encyclopédique et méthodique des trois règnes de la nature... Ichthyologie. Paris. Tableau encyclopédique et méthodique des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Joseph Bonnaterre
Abbé Pierre Joseph Bonnaterre (1752, Aveyron – 20 September 1804, Saint-Geniez-d'Olt) was a French zoology, zoologist who contributed sections on cetaceans, mammals, birds, reptiles, amphibians, fish, and insects to the ''Tableau encyclopédique et méthodique''. He is also notable as the first scientist to study the feral child Victor of Aveyron. Bonnaterre is credited with identifying about 25 new species of fish, and assembled illustrations of about 400 in his encyclopedia work of book. He was the first scientist to study Victor, the wild child of Aveyron, whose life inspired François Truffaut for his film ''The Wild Child''. Partial bibliography * ''Tableau encyclopédique et méthodique des trois règnes de la nature, dix-huitième partie, insectes.'' Agasse, Paris 1797. * ''Recueil de médecine vétérinaire ou Collection de mémoires d'instructions et de recettes sur les maladies des animaux domestiques.'' * ''Tableau encyclopédique et méthodique des trois règn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constantine Samuel Rafinesque
Constantine Samuel Rafinesque-Schmaltz (; October 22, 1783September 18, 1840) was a French 19th-century polymath born near Constantinople in the Ottoman Empire and self-educated in France. He traveled as a young man in the United States, ultimately settling in Ohio in 1815, where he made notable contributions to botany, zoology, and the study of prehistoric earthworks in North America. He also contributed to the study of ancient Mesoamerican linguistics, in addition to work he had already completed in Europe. Rafinesque was an eccentric and erratic genius. He was an autodidact, who excelled in various fields of knowledge, as a zoologist, botanist, writer and polyglot. He wrote prolifically on such diverse topics as anthropology, biology, geology, and linguistics, but was honored in none of these fields during his lifetime. Indeed, he was an outcast in the American scientific community whose submissions were rejected automatically by leading journals. Among his theories were th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
