Porpoises are small dolphin-like cetaceans classified under the family Phocoenidae. Although similar in appearance to dolphins, they are more closely related to narwhals and belugas than to the true dolphins. There are eight extant species of porpoise, all among the smallest of the toothed whales. Porpoises are distinguished from dolphins by their flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and lack of a pronounced beak, although some dolphins also lack a pronounced beak. Porpoises, and other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates.
Orcinus is a genus of Delphinidae, the family of carnivorous marine mammals known as dolphins. It includes the largest delphinid species, Orcinus orca, known as the orca or killer whale. Two extinct species are recognised, Orcinus paleorca and O. citoniensis, describing fossilised remains of the genus. The other extinct species O. meyeri is disputed.
The snubfin dolphins (Orcaella) are a genus of cetaceans containing two members: the Irrawaddy dolphin and the Australian snubfin dolphin. The genus was long believed to be monotypic with the only species being the Irrawaddy dolphin; however, in 2005, supposed Irrawaddy dolphin populations inhabiting the Australian/New Guinean regions were found to be significantly different and were declared a separate new species named the Australian snubfin dolphin.
The rough-toothed dolphin is a species of dolphin that can be found in deep warm and tropical waters around the world.
The false killer whale is a species of oceanic dolphin that is the only extant representative of the genus Pseudorca. It is found in oceans worldwide but mainly in tropical regions. It was first described in 1846 as a species of porpoise based on a skull, which was revised when the first carcasses were observed in 1861. The name "false killer whale" comes from having a skull similar to the orca, or killer whale.
The Indo-Pacific bottlenose dolphin is a species of bottlenose dolphin. This dolphin grows to 2.6 m (8.5 ft) long, and weighs up to 230 kg (510 lb). It lives in the waters around India, northern Australia, South China, the Red Sea, and the eastern coast of Africa. Its back is dark grey and its belly is lighter grey or nearly white with grey spots.
The Indian Ocean humpback dolphin is a member of the Delphinidae family occupying coastal areas ranging from Southern Africa to Western Indochina. The Indo-Pacific humpback dolphin was formerly included within the same species, but a 2014 study revealed them to be a separate species.
Fraser's dolphin or the Sarawak dolphin is a cetacean in the family Delphinidae found in deep waters in the Pacific Ocean and to a lesser extent in the Indian and Atlantic Oceans.
Lagenorhynchus is a genus of oceanic dolphins in the infraorder Cetacea, presently containing six extant species. However, there is consistent molecular evidence that the genus is polyphyletic and several of the species are likely to be moved to other genera. In addition, the extinct species Lagenorhynchus harmatuki is also classified in this genus.
The northern right whale dolphin is a small, slender species of cetacean found in the cold and temperate waters of the North Pacific Ocean. Lacking a dorsal fin, and appearing superficially porpoise-like, it is one of the two species of right whale dolphin.
The hourglass dolphin is a small dolphin in the family Delphinidae that inhabits offshore Antarctic and sub-Antarctic waters. It is commonly seen from ships crossing the Drake Passage, but has a circumpolar distribution.
Peale's dolphin is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work Peale's dolphin has been adopted as the standard common name.
The striped dolphin is an extensively researched dolphin found in temperate and tropical waters of all the world's oceans. It is a member of the oceanic dolphin family, Delphinidae.
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya. Cetaceans are thought to have evolved during the Eocene, the second epoch of the present-extending Cenozoic Era. Molecular and morphological analyses suggest Cetacea share a relatively recent closest common ancestor with hippopotami and that they are sister groups. Being mammals, they surface to breathe air; they have 5 finger bones (even-toed) in their fins; they nurse their young; and, despite their fully aquatic life style, they retain many skeletal features from their terrestrial ancestors. Research conducted in the late 1970s in Pakistan revealed several stages in the transition of cetaceans from land to sea.
Australodelphis mirus is an extinct Pliocene dolphin. A. mirus is known from fossils found in the Sørsdal Formation, Mule Peninsula, Vestfold Hills, East Antarctica. The genus has been described as an example of convergent evolution with beaked whales.
The Kattendijk Formation is a five million years old marine geological formation north of Antwerp, Belgium. including the north-western parts of the Campine region. The area was named by De Heuter and Laga in 1976. The sands range from medium fine to coarse and contain a large proportion of shell grit.
Etruridelphis is an extinct genus of cetacean.
Auroracetus, from Aurora and the Latin cetus (whale), is a genus of Pontoporiidae, the river dolphins, and contains one extinct species. The species Auroracetus bakerae was published in 2009.
Eodelphinus is an extinct genus of oceanic dolphins belonging to the family Delphinidae.
