The Squaliformes are an order of sharks that includes about 126 species in seven families.
Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under Squaliformes, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. As the species reaches adulthood, males usually measure a maximum of 100 cm, while females typically measure 125 cm long. The species therefore exhibits female-dominant sexual dimorphism.
Squalicorax, commonly known as the crow shark, is a genus of extinct lamniform shark known to have lived during the Cretaceous period. The genus had a global distribution in the Late Cretaceous epoch. Multiple species within this genus are considered to be wastebasket taxon due to morphological similarities in the teeth.
The spiny dogfish, spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family of sharks, which is part of the Squaliformes order.
Squalus is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of Squalus would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that Squalus is quite capable of protruding its upper jaw during feeding.
The mandarin dogfish is a dogfish, a member of the family Squalidae in the order Squaliformes. It is found at depths of 140–650 metres (460–2,130 ft) off southern Japan, Taiwan, and Indonesia. Populations off Australia and New Zealand were formerly included in this species, but in 2007 these were assigned to a new species, the southern mandarin dogfish. It is not clear which of these species is involved in other populations from the tropical West Pacific.
The Cuban dogfish is a dogfish, a member of the family Squalidae in the order Squaliformes.
The taillight shark is a little-known species of shark in the family Dalatiidae and the only member of its genus. It is known from only four specimens collected from deep oceanic waters in the southern Atlantic Ocean and Pacific Ocean. A small shark with a laterally compressed body and a bulbous snout, this species has unusual adaptations that indicate a specialized lifestyle: its pectoral fins are paddle-like and may be used for propulsion, unlike other sharks and it has a pouch-like gland on its abdomen that emits clouds of luminescent blue fluid. This shark is likely aplacental viviparous and a formidable predator for its size.
The viper dogfish or viper shark is a rare species of dogfish shark in the family Etmopteridae, and the only extant member of its genus. It has been found in the Pacific Ocean off southern Japan, the Bonin Islands, Pacific Ocean off northern Taitung County and the Northwestern Hawaiian Islands. This species inhabits upper continental slopes and seamounts. It may migrate vertically, shifting between bottom waters 270–360 m (890–1,180 ft) deep during the day and upper waters less than 150 m (490 ft) deep at night. A slender, black shark reaching 54 cm (21 in) in length, the viper dogfish can be recognized by its narrow, triangular jaws and well-spaced, fang-like teeth. It also has two spined dorsal fins, dermal denticles with faceted crowns, and numerous light-emitting photophores concentrated on its ventral surface.
The blacktailed spurdog is a dogfish, a member of the family Squalidae, found around New Caledonia in the central Pacific Ocean, at depths from 320 to 320 m. Its length is up to 75 cm.
The shortspine spurdog is a dogfish, a member of the family Squalidae, found on continental shelves off Japan in temperate waters, from the surface to 950 m. Its length is up to 75 cm.
Anomotodon is an extinct genus of shark related to the extant goblin shark. The distribution of Anomotodon fossils is worldwide, in formations indicating that members of the genus lived from the Early Cretaceous epoch through the Eocene epoch, and perhaps through the Oligocene as well. Described species include A. novus, A. plicatus, A. principalis, and A. multidenticula.
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.
Cretalamna is a genus of extinct otodontid shark that lived from the latest Early Cretaceous to Eocene epoch. It is considered by many to be the ancestor of the largest sharks to have ever lived, such as Otodus angustidens, Otodus chubutensis, and Otodus megalodon.
The Northumberland Formation is a Late Cretaceous (?Campanian-?Maastrichtian)-aged geologic formation in Canada. It belongs to the larger Nanaimo Group. Indeterminate bird and pterosaur fossils have been recovered from the formation, as well as a potential gladius of Eromangateuthis. An extensive diversity of shark teeth is known from the formation; many appear to be closely allied with modern deep-water shark taxa, suggesting a deep-water environment for the formation. The most well-known exposures of the formation are on Hornby Island.
Mcmurdodus is an extinct genus of chondrichthyan belonging to the family Mcmurdodontidae. It contains one species, Mcmurdodus featherensis, from the Middle Devonian of Antarctica. The Australian species M. whitei was previously included in the genus too, but was moved to a new genus, Maiseyodus, in 2021.
The Pacific spiny dogfish is a common species of the Squalidae (dogfish) family of sharks and are among the most abundant species of sharks in the world. This species is closely related to Squalus acanthias and for many years they were treated as a single species. Recent research, using meristic, morphological and molecular data led to the resurrection of the Pacific spiny dogfish as a separate species. The American Fisheries Society recommends the common name "Pacific spiny dogfish" for Squalus suckleyi over alternatives such as "spotted spiny dogfish" and "North Pacific spiny dogfish" and "spiny dogfish" for Squalus acanthias.
Xiphodolamia is a rare extinct genus of mackerel shark which lived during the Eocene epoch. It is only known from isolated teeth, but has been found in Europe, Africa, and Asia. It is assumed to be pelagic, occurring more frequently in deeper water deposits, most notably the London Clay and Eocene deposits in Denmark. It is distinguished by its rectangular root and twisted blade, unique among mackerel sharks. It is unclear what niche this specialized dentition helped exploit.
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.
Protocentrophorus is a genus of was a genus of dogfish shark that existed during the Cretaceous. Fossils have been found in the Tauragė County of Lithuania and British Columbia in Canada. Known from teeth, they were originally assigned to the genus Centrophorus.
