A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans ideal for their marine environments, including most numerously fish, but also mammals such as cetaceans, and even extinct ancient marine reptiles such as various known species of ichthyosaurs. Most species have only one dorsal fin, but some have two or three.
The Cetomimiformes or whalefishes are an order of small, deep-sea ray-finned fish. Some authorities include the whalefishes as part of the order Stephanoberyciformes, within the superfamily Cetomimoidea. Their sister order, the Beryciformes, includes the flashlight fish and squirrelfish.
Dimetrodon is an extinct genus of non-mammalian synapsid that lived during the Cisuralian, around 295–272 million years ago (Mya). It is a member of the family Sphenacodontidae. The most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It walked on four legs and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the Southwestern United States, the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma. More recently, fossils have been found in Germany. Over a dozen species have been named since the genus was first erected in 1878.
Ridgeheads, also known as bigscales, are a family of small, deep-sea stephanoberyciform fish. The family contains approximately 37 species in five genera; their distribution is worldwide, but ridgeheads are absent from the Arctic Ocean and Mediterranean Sea. Although the family is one of the most widespread and plentiful of deep-sea families, none of its members are of interest to commercial fishery.
The channel catfish is North America's most numerous catfish species. It is the official fish of Kansas, Missouri, Iowa, Nebraska, and Tennessee, and is informally referred to as a "channel cat". In the United States, they are the most fished catfish species with around 8 million anglers targeting them per year. The popularity of channel catfish for food has contributed to the rapid expansion of aquaculture of this species in the United States. It has also been widely introduced in Europe, Asia and South America, and it is legally considered an invasive species in many countries.
The louvar or luvar is a species of perciform fish, the only extant species in the genus Luvarus and family Luvaridae. It is closely related to the surgeonfish. The juvenile form has a pair of spines near the base of the tail, like the surgeonfish, though they are lost in the adult.
Heliobatis is an extinct genus of stingray in the Myliobatiformes family Dasyatidae. At present the genus contains the single species Heliobatis radians.
The sargassum fish, anglerfish, or frog fish is a frogfish of the family Antennariidae, the only species in its genus. It lives among Sargassum seaweed which floats in subtropical oceans. The scientific name comes from the Latin histrio meaning a stage player or actor, and refers to the fish's feeding behaviour.
The decoy scorpionfish is a species of marine ray-finned fish belonging to the family Scorpaenidae, the scorpionfishes. It is native to the Western Indian and Pacific oceans. A non-migratory species, I. signifer can be observed in close association with coral reefs at depths of from 10 to 70 metres. This species grows to a length of 13 centimetres (5.1 in) TL. This species is the only known member of its genus and can be distinguished by its unique prey-luring behavior.
The Asian whiting, Sillago asiatica, is a species inshore marine fish in the smelt whiting family, Sillaginidae, distributed along the Asian coastline from the Gulf of Thailand to Taiwan. The Asian whiting's appearance is very similar to other closely related species in the genus Sillago, with swim bladder morphology and ray counts of fins the most reliable identifying features. The species inhabits slightly deeper water than many of the sillaginid species its distribution overlaps, forming an important part of the whiting fishery in the countries within its range.
Caesionidae, the fusiliers, are a family of marine ray-finned fishes in the order Perciformes. The family includes about 23 species. They are related to the snappers, but adapted for feeding on plankton, rather than on larger prey. They are found at reefs in the Indo-Pacific and in the Red Sea.
Arizonerpeton is an extinct genus of nectridean lepospondyl. It contains a single species, Arizonerpeton wellsi. It lived in what is now the Swisshelm Mountains of modern-day Arizona, United States. This locality belongs to the Black Prince Limestone Formation, which is dated to the middle Pennsylvanian sub-period of the Carboniferous period.
The black rockfish, also known variously as the black seaperch, black bass, black rock cod, sea bass, black snapper and Pacific Ocean perch, is a species of marine ray-finned fish belonging to the subfamily Sebastinae, the rockfishes, part of the family Scorpaenidae. It is sometimes misidentified as the "red snapper".
Iguanacolossus is a genus of iguanodontian ornithopod dinosaur that lived in North America during the Early Cretaceous period. It is known from UMNH VP 20205, the associated holotype with a large partial skeleton of a single individual.
The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord found in all chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as lumbar punctures. The vertebral column houses the spinal canal, a cavity that encloses and protects the spinal cord.
Concavispina is an extinct genus of thalattosaur reptile from the early Late Triassic Xiaowa Formation of Guangling, Guizhou, southern China. It contains a single species, Concavispina biseridens. It is known only from the holotype ZMNH M8804, a nearly complete 364 cm long skeleton. Concavispina can be differentiated from other thalattosaurs by possessing two rows of blunt teeth on the anterior part of the maxilla and a V-shaped notch on the dorsal margin of each neural spine in the dorsal (back) vertebrae. Both its generic and specific names refer to these autapomorphies, as Concavispina means "concave spine" and biseridens means "two rows of teeth". It is thought to be most closely related to Xinpusaurus, as both taxa share three derived characters: a maxilla that is curved upward at its anterior end, a humerus that is wider near the shoulder than near the elbow, and the presence of less than five cervicals.
Astyanax microschemos is a species of characid fish from Brazil. It belongs to the A. scabripinnis species complex and differs from other species outside it by having a lower number of branched anal fin rays and its shallow body depth being about 26.9-29.7 vs more than 35% of its standard length (SL). Compared to species of its own complex, it can be distinguished by the combination of its shallow body depth, and smaller interorbital width. The species name comes from the Greek mikroschemos, meaning "low stature", which refers to the shallow body depth of the animal.
Anguanax is an extinct genus of basal pliosaurid known from the Late Jurassic Rosso Ammonitico Veronese Formation of northern Italy. It contains a single species, Anguanax zignoi, known from a partially complete individual, representing the first articulated skeleton of an Italian plesiosaurian.
Siamraptor is an extinct genus of carcharodontosaurian dinosaur, containing the single species S. suwati, known from the Khok Kruat Formation of Thailand. It is the first definitive named carcharodontosaurian species known from Southeast Asia.
Incertovenator is an extinct genus of archosauriform reptile, likely an archosaur, of uncertain affinities. Its unstable position is a result of possessing a number features found in both the bird-line avemetatarsalian archosaurs and the crocodylian-line pseudosuchians. The type and only known species is I. longicollum, which is known from single specimen discovered in the Late Triassic Ischigualasto Formation of Argentina. Incertovenator is known almost entirely by its vertebral column. This indicates that it had a relatively long neck, leading to its uncertain classification due to the convergent evolution of elongated neck vertebrae in both avemetatarsalian and pseudosuchian archosaurs.
