Carcharhiniformes, the ground sharks, are the largest order of sharks, with over 270 species. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark.
The Hexanchiformes are a primitive order of sharks, that numbering just seven extant species in two families. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.
Chlamydoselachidae is a family of primitive deep-sea sharks in the order Hexanchiformes. They are one of only two extant families in the order alongside the cow sharks in the family Hexanchidae, and the only members of the suborder Chlamydoselachoidei.
Chlamydoselachus is a genus of sharks and the sole extant member of the family Chlamydoselachidae, in the order Hexanchiformes. It contains two extant and four extinct species. The most widely known species still surviving is the frilled shark. It is known as a living fossil, along with Chlamydoselachus africana, also known as the southern African frilled shark, which is only found along coastal areas of South Africa. The only two extant species of this genus are deep-sea creatures which are typically weakened in areas closer to the surface. While the two extant species are similar in external appearance, they differ internally.
Hornby Island of British Columbia, Canada, is one of the two northernmost Gulf Islands, the other being Denman Island. It is located near Vancouver Island's Comox Valley,
Philip John Currie is a Canadian palaeontologist and museum curator who helped found the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta and is now a professor at the University of Alberta in Edmonton. In the 1980s, he became the director of the Canada-China Dinosaur Project, the first cooperative palaeontological partnering between China and the West since the Central Asiatic Expeditions in the 1920s, and helped describe some of the first feathered dinosaurs. He is one of the primary editors of the influential Encyclopedia of Dinosaurs, and his areas of expertise include theropods, the origin of birds, and dinosaurian migration patterns and herding behavior. He was one of the models for palaeontologist Alan Grant in the film Jurassic Park.
Gasteroclupea is a genus of prehistoric ellimmichthyiform fish that is distantly related to modern anchovies and herrings. It contains one species, G. branisai. It inhabited freshwater or estuarine habitats across South America during the Campanian and Maastrichtian stages of the Late Cretaceous period, and it briefly survived beyond the K-Pg boundary into the Danian stage of the Paleocene, making it among the few genera from its order to survive into the Cenozoic. Fossils of the genus have been found in the Yacoraite Formation of Argentina, the Chaunaca Formation, Santa Lucía Formation, and El Molino Formation of Bolivia, and the Navay Formation in Venezuela.
Istiodactylidae is a small family of pterosaurs. This family was named in 2001 after the type genus Istiodactylus was discovered not to be a member of the genus Ornithodesmus.
The Tuchengzi Formation is a geological formation in China whose strata span the Tithonian to Berriasian ages. Dinosaur fossils, particularly footprints, have been found from the formation.
Paraorthacodus is an extinct genus of shark. It a member of the family Paraorthacodontidae, which is either placed in Hexanchiformes or in Synechodontiformes. It is known from over a dozen named species spanning from the Early Jurassic to the Paleocene, or possibly Eocene. Almost all members of the genus are exclusively known from isolated teeth, with the exception of P. jurensis from the Late Jurassic-Early Cretaceous of Europe, which is known from full body fossils from the Late Jurassic of Germany, which suggest that juveniles had a robust body with a round head, while adults had large body sizes with a fusiform profile. There was only a single dorsal fin towards the back of the body without a fin spine. The dentition had teeth with a single large central cusp along with shorter lateral cusplets, which where designed for clutching. The teeth are distinguished from those of Synechodus by the lateral cusplets decreasing in size linearly away from the central cusp rather than exponentially as in Synechodus.
Synechodontiformes is an extinct order of prehistoric shark-like cartilaginous fish, known from the Permian to the Paleogene. They are considered to be members of Neoselachii, the group that contains modern sharks and rays.
Naomichelys is an extinct genus of helochelydrid stem turtle known from the Cretaceous (Aptian-Campanian) of North America. It is the only member of the family known to be native to North America.
Notidanodon is an extinct genus of cow shark. Fossils ascribed to this genus are known from the Jurassic and Cretaceous periods. Recently, the genus underwent a major revision and was split into two after the erection of Xampylodon to accommodate the species X. dentatus, X. loozi, and X. brotzeni. The genus is now known only from New Zealand, Antarctica, Africa, and South America.
Adnetoscyllium is an extinct genus of bamboo shark from the Cretaceous period. It is currently monotypic, containing only the species A. angloparisensis. The genus is named for prominent paleoichthyologist, Dr. Sylvain Adnet. The specific epithet refers to the range which is thus far restricted to the Anglo-Paris Basin of France and the United Kingdom.
Ctenacanthiformes is an extinct order of cartilaginous fish. They possessed ornamented fin spines at the front of their dorsal fins and cladodont-type dentition, that is typically of a grasping morphology, though some taxa developed cutting and gouging tooth morphologies. Some ctenacanths are thought to have reached sizes comparable to the great white shark, with body lengths of up to 7 metres (23 ft) and weights of 1,500–2,500 kilograms (3,300–5,500 lb). The earliest ctenacanths appeared during the Frasnian stage of the Late Devonian, with the group reaching their greatest diversity during the Early Carboniferous (Mississippian), and continued to exist into at least the Middle Permian (Guadalupian). Some authors have suggested members of the family Ctenacanthidae may have survived into the Cretaceous based on teeth found in deep water deposits of Valanginian age in France and Austria, however, other authors contend that the similarity of these teeth to Paleozoic ctenacanths is only superficial, and they likely belong to neoselachians instead.
Hessinodon is an extinct genus of possible kitefin sharks that lived during the Late Cretaceous. It contains one valid species, H. wardi, which is known from four teeth from the Northumberland Formation of British Columbia. Its teeth are most similar to those of modern cookiecutter sharks.
Rolfodon is an extinct genus of shark in the family Chlamydoselachidae. It is closely related to the extant frilled sharks in the genus Chlamydoselachus, which it can be differentiated from by tooth morphology. It is named after late Canadian paleontologist Rolf Ludvigsen.
Dykeius is an extinct genus of large shark in the family Chlamydoselachidae. It contains a single known species, D. garethi, from the Late Cretaceous Northumberland Formation of Canada. The genus and species names honor paleontologist Gareth J. Dyke.
Komoksodon is an extinct genus of hexanchiform shark known from the Late Cretaceous to the Paleocene. It is the only member of the monotypic family Komoksodontidae.
Xampylodon is an extinct genus of cow shark. Fossils assigned to this genus are known from the Late Cretaceous and early Paleocene. Xampylodon was recently erected after a revision on the taxonomy of hexanchid fossil teeth, and includes three species previously included in Notidanodon.
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