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.
Hybodus is an extinct genus of hybodont, a group of shark-like euselachians that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type species Hybodus reticulatus lived during the Early Jurassic epoch. Numerous species have been assigned to Hybodus spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination.
Rhombodus is a prehistoric genus of ray belonging to the family Rhombodontidae.
Ischyrhiza is an extinct genus of sclerorhynchoid ray from the Late Cretaceous and Early Paleogene.
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.
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, and the Aptian-Albian of France. 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.
Mcmurdodus is an extinct genus of chondrichthyan from Antarctica and Australia and the sole member of the family Mcmurdodontidae. It contains two extinct species. However, the Australian species M. whitei has been found to be different from the Antarctic type species M. featherensis, and thus M. whitei has been classified into a new genus, Maiseyodus.
Ptychotrygon is a genus of sawfish-like Late Cretaceous ray whose fossils have been found worldwide. It, Ptychotrygonoides, Texatrygon, and Asflapristis are members 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 and their closest living relatives are actually skates. While they are often called "sawfishes", sawskates is a more accurate common name for sclerorhynchoids. The suborder contains five named families: Ganopristidae, Ischyrhizidae, Onchopristidae, Ptychotrygonidae, and Schizorhizidae. Several genera are not currently placed in any of these families. Sclerorhynchoids first appeared in the Barremian and went extinct during the Cretaceous–Paleogene extinction event, with former Paleocene occurrences being misidentifications or reworked specimens.
Synechodontiformes is an extinct order of prehistoric shark-like neoselachians, 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 genu was first described in 1911 by Ernst Hermann Friedrich von Koken in Karl Alfred von Zittel.
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.
