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.
Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule.
Ischyrhiza is an extinct genus of sclerorhynchoid ray from the Late Cretaceous (Cenomanian-Maastrichtian).
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays (Neoselachii) as part of the clade Euselachii. They are distinguished from other chondrichthyans by their distinctive fin spines and cephalic spines present on the heads of males. An ecologically diverse group, they were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct.
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.
Meristodonoides is an extinct genus of hybodont. The type species is M. rajkovichi, which was originally a species in the genus Hybodus. The species, along with other Hybodus species such as H. butleri and H. montanensis, was reassigned to Meristodonoides by Charlie J. Underwood and Stephen L. Cumbaa in 2010. The species is primarily known from remains from the Cretaceous of North America, spanning from the Aptian/Albian to Maastrichtian, making it one of the last surviving hybodont genera, though records of the genus likely extend back as far as the Late Jurassic, based on an undescribed skeleton from the Tithonian of England, and fragmentary teeth from the Kimmeridgian of Poland, England and Switzerland. Other remains of the genus are known from the Coniacian of England, the Aptian-Albian of France, and the Campanian of European Russia. The morphology of the teeth suggests an adaptation to tearing prey. Fossils from the Western Interior Seaway suggest that it preferred nearshore marine environments, being absent from deeper-water areas, with it likely also being able to tolerate brackish and freshwater conditions.
Ptychotrygon is a genus of sawfish-like ray whose fossils have been found worldwide from the Cretaceous period (Albian-Maastrichtian). Along with Ptychotrygonoides, Texatrygon, and Asflapristis, it is the member of the family Ptychotrygonidae within the suborder Sclerorhynchoidei.
Pseudocorax is an extinct genus of mackerel sharks that lived during the Late Cretaceous. It contains six valid species that have been found in Europe, the Middle East, North Africa, and North America. It was formerly assigned to the family Anacoracidae, but is now placed in its own family Pseudocoracidae along with Galeocorax. The former species "P." australis and "P." primulus have been reidentified as species of Echinorhinus and Squalicorax, respectively.
Sclerorhynchoidei is an extinct suborder of rajiform rays that had long rostra with large denticles similar to sawfishes and sawsharks. This feature was convergently evolved, recently proposed as 'pristification', and their closest living relatives are actually skates. While they are often called "sawfishes", sawskates is a more accurate common name proposed in 2021 for sclerorhynchoids, which has been subsequently used by other researchers.
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.
Paracestracion is an extinct genus of heterodontiform sharks from Early Jurassic to Early Cretaceous-aged rocks of England, France, Germany and Luxembourg. The genus was first described in 1911 by Ernst Hermann Friedrich von Koken in Karl Alfred von Zittel.
Synechodus is an extinct genus of shark belonging to the family Palaeospinacidae and order Synechodontiformes. It is known from 16 species primarily spanning from the Late Triassic to Paleocene. The dentition is multicusped and was used for grasping. Several species are known from skeletal remains, including the species Synechodus ungeri from the Late Jurassic of Germany, which shows that it was relatively short with large pectoral fins and a proportionally large head with a round snout. This species is suggested to have reached a body length of 30–40 centimetres (0.98–1.31 ft). Skeletal remains are also known of the species Synechodus dubrisiensis from the Cretaceous of Europe. A skeleton of an indeterminate species is also known from the Early Cretaceous (Albian) of France, with a body length of around 70 centimetres (2.3 ft). Synechodus is suggested to have had two dorsal fins that lacked fin spines, though the number of dorsal fins is unknown in Synechodus ungeri.
Iberotrygon is an extinct genus of sclerorhynchiform ray from the Cenomanian Mosqueruela Formation of Spain. Only the single species I. plagiolophus, is known; it was named and described in 2009. It is known from the holotype MPZ 2005-33, an antero-lateral tooth, and the parartypes MPZ 2005-34, four well-preserved teeth from a single juvenile?, and MPZ 2005-35, an isolated tooth.
Protolamna is an extinct genus of mackerel shark from the Cretaceous Period. The genus is known from Europe, Asia and North America.
Eoptolamna is an extinct genus of mackerel sharks that lived during the Cretaceous. It contains two valid species, E. eccentrolopha and E. supracretacea, which have been found in Europe and North Africa.
Acutalamna is an extinct genus of mackerel shark from the Cretaceous period. It contains a singular species, A. karsteni. The type locality is the La Luna formation of Venezuela, but teeth have been found in France, Peru, Ecuador, and Lithuania. It is possible these teeth represent new species within this genus. Teeth included in this genus were originally attributed to "Priscusurus adruptodontus". The holotype and some of type series of this species were found to be indeterminate Squalicorax teeth, thus rendering it a nomen dubium. Other teeth in the type series of "P. adruptodontus" are indeterminate members of Acutalamna. It bears resemblance to both Anacoracids and Cretoxyrhinids, but has yet to be confidently ascribed to any family.
Cantioscyllium is an extinct genus of nurse shark from the Mesozoic era. It is known mainly from isolated teeth, but was named on a partial skeleton from the Late Cretaceous of England. It is a widespread and diverse genus, currently containing 10 species. They are uncommon but present throughout the late cretaceous of the eastern United States, including the Severn Formation of Maryland, the Tar Heel and Peedee formations of North Carolina, and Campanian of New Jersey. It is also known from the Western Interior Seaway and western Europe. C. hashimiaensis is known from the Santonian of Jordan. C. alhaulfi is from the Barremian.
Pseudoscapanorhynchidae is a family of extinct mackerel sharks that lived during the Cretaceous and potentially the Paleogene. It currently includes Cretodus, Eoptolamna, Leptostyrax, Protolamna, Pseudoscapanorhynchus, and possibly Lilamna.
Crassodontidanidae is a family of extinct cow sharks that lived from the Early Jurassic to the Early Cretaceous. It contains three genera: Crassodontidanus, Notidanoides, and Pachyhexanchus.
Pseudocoracidae is a family of extinct mackerel sharks that lived during the Late Cretaceous. It includes two genera, Galeocorax and Pseudocorax.
