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The Lamniformes are an order of sharks commonly known as mackerel sharks. It includes some of the most familiar species of sharks, such as the great white, as well as more unusual representatives, such as the goblin shark and megamouth shark.
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including the sharks and the rays, skates, and sawfish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.
The basking shark is the second-largest living shark, after the whale shark, and one of three plankton-eating shark species, along with the whale shark and megamouth shark. Adults typically reach 7.9 m (26 ft) in length. It is usually greyish-brown, with mottled skin. The caudal fin has a strong lateral keel and a crescent shape.
Orthacanthus is an extinct genus of fresh-water xenacanthid sharks, named by Louis Agassiz in 1836, ranging from the Upper Carboniferous until the Lower Permian. Orthacanthus lived in marine environments and had a nektobenthic life habitat, with a carnivorous diet. Multiple sources have also discovered evidence of cannibalism in the diet of Orthacanthus and of "filial cannibalism" where adult Orthacanthus preyed upon juvenile Orthacanthus. The genus Orthacanthus has been synonymized with Dittodus, Didymodus, and Diplodus.
Hybodus is an extinct genus of Chondrichthyans. First appearing towards the end of the Permian period, and disappearing during the Late Cretaceous, during the Triassic, Jurassic, and Cretaceous periods the hybodonts were especially successful and could be found in shallow seas across the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period.
Physogaleus is a small genus of prehistoric shark that lived from the Eocene to Miocene epochs.
Cephaloscyllium is a genus of catsharks, and part of the family Scyliorhinidae, commonly known as swellsharks because of their ability to inflate their bodies with water or air as a defense against predators. These sluggish, bottom-dwelling sharks are found widely in the tropical and temperate coastal waters of the Indian and Pacific Oceans. They have stocky, spindle-shaped bodies and short, broad, and flattened heads. The mouth is capacious, containing many small teeth and lacking furrows at the corners. The two dorsal fins are placed far back on the body, with the first much larger than the second. Different species have various color patterns of saddles, blotches, reticulations, and/or spots. The largest members of the genus can grow over 1 m (3.3 ft) in length. Swellsharks prey on a variety of fishes and invertebrates, and are oviparous, with females producing egg capsules in pairs. They are harmless and have been deemed of having no commercial value.
Ptychodus is a genus of extinct sharks. As well as a genus of durophagous (shell-crushing) sharks from the Late Cretaceous. Fossils of Ptychodus teeth are found in many Late Cretaceous marine sediments. There are many species among the Ptychodus that have been uncovered on all the continents around the globe. Such species are Ptychodus mortoni, P. decurrens, P. marginalis, P. mammillaris, P. rugosus and P. latissimus to name a few. They died out approximately 85 million years ago in the Western Interior Sea, where a majority of them were found. A recent publication found that Ptychodus are likely neoselachians, rather than hybodonts or batoids as previously thought.
Hybodontiformes, also called hybodonts, are an extinct subset of Elasmobranchii which existed from the late Devonian to the Late Cretaceous. They form the group of sharks closest to neoselachians, the clade of modern sharks and rays. Hybodonts were named and are distinguished based on their conical tooth shape. They comprised the main group of Jurassic sharks in Europe and North America. They survived into the Late Cretaceous before going extinct, possibly due to competition from other sharks. Lonchidion was one of the last hybodonts — its distinctive serrated fine spines occur in freshwater deposits from Wyoming alongside the fossils of the last dinosaurs, including Tyrannosaurus rex and Triceratops. Hybodontiformes are identified in the fossil record predominantly based on distinct teeth and fin spines. They were known to live in both fresh and salt water environments.
Lissodus is an extinct genus of freshwater shark. It lived from the Early Carboniferous stage to the Albian age of the Cretaceous. It was about 15 centimetres (5.9 in) long and had flat teeth that it used for eating clams.
Gladioserratus is an extinct genus of cow shark. It contains three species:
Eosqualiolus is an extinct genus of sharks in the family Dalatiidae. It was described by Sylvain Adnet in 2006, and the type species is E. aturensis, which existed during the middle Eocene of what is now France. A new species, E. skrovinai, which existed in what is now Slovakia during the Miocene period, was described by Charlie J. Underwood and Jan Schlogl in 2012, and named in honour of Michal Škrovina. E. skrovinai was described from 14 fossil teeth found in the Laksarska Nova Ves Formation; 9 upper and 5 lower, some of which were partial and some were complete.
Paraetmopterus is an extinct genus of sharks in the family Etmopteridae. It was described by Adnet in 2006, and the type species is P. nolfi, which existed during the middle Eocene of France. A new species, P. horvathi, which existed in what is now Slovakia during the Miocene epoch, was described by Charlie J. Underwood and Jan Schlögl in 2013; however, this species was subsequently transferred to the separate genus Palaeocentroscymnus.
Pristiophorus striatus is an extinct species of sawshark in the genus Pristiophorus. It existed in what is now Slovakia during the Miocene epoch, and was described by Charlie J. Underwood and Jan Schlogl in 2012.
Cretorectolobus is an extinct carpet shark. It was described by G.R. Case in 1978, and the type species is C. olsoni, which existed during the Campanian in Canada and the United States. Another species, C. gracilis, was described by Charlie J. Underwood and Mitchell in 1999, from the Hauterivian to Barremian strata of the Speeton Clay Formation of England. The species epithet refers to the shark's teeth, which Underwood and Mitchell described as gracile and narrow in form. A new species, C. robustus, was described from the Cenomanian of Canada by Underwood and Stephen L. Cumbaa in 2010.
Scaldicetus is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct physeterids with primitive dental morphology consisting of enameled teeth, Scaldicetus as generally recognized appears to be a wastebasket taxon filled with more-or-less unrelated primitive sperm whales.
This list of fossil fishes described in 2013 is a list of new taxa of placoderms, fossil cartilaginous fishes and bony fishess of every kind that have been described during the year 2013. The list only includes taxa at the level of genus or species.
Serratolamna is an extinct genus of mackerel sharks belonging to the family Cretoxyrhinidae.
Eoptolamna is an extinct genus of mackerel shark from the Cretaceous Period. It currently holds two species. E. eccentrolopha is described from the Barremian and Albian Artoles Formation of Spain. E. supracretacea is known from the lower Santonian to middle Campanian of the Anglo-Parisian Basin.
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.
References
- 1 2 3 4 5 6 Charlie J. Underwood and Jan Schlogl (2011). "Deep water chondrichthyans from the Early Miocene of the Vienna Basin (Central Paratethys, Slovakia)". Acta Palaeontologica Polonica. in press. doi: 10.4202/app.2011.0101 .