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Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]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. [2]
The following is a list of currently existing (or, in the jargon of taxonomy) 'extant' species of the infraorder cetacea (for extinct cetacean species, see the list of extinct cetaceans). The list is organized taxonomically into parvorders, superfamilies when applicable, families, subfamilies when applicable, genus, and then species.
Representing the earliest cetacean radiation, they include the initial amphibious stages in cetacean evolution, thus are the ancestors of both modern cetacean suborders, Mysticeti and Odontoceti. [2] This initial diversification occurred in the shallow waters that separated India and Asia 53 to 45 mya , resulting in some 30 species adapted to a ...
Cetacean eyes are set on the sides rather than the front of the head. This means only species with pointed 'beaks' (such as dolphins) have good binocular vision forward and downward. Tear glands secrete greasy tears, which protect the eyes from the salt in the water. The lens is almost spherical, which is most efficient at focusing the minimal ...
The list of extinct cetaceans features the extinct genera and species of the order Cetacea.The cetaceans (whales, dolphins and porpoises) are descendants of land-living mammals, the even-toed ungulates.
Modern cetaceans are highly adapted sea creatures which, morphologically, have little in common with land mammals; they are similar to other marine mammals, such as seals and sea cows, due to convergent evolution. However, they evolved from originally terrestrial mammals.
The name Whippomorpha is a combination of English (wh[ale] + hippo[potamus]) and Greek (μορφή, morphē = form). [2]Some attempts have been made to rename the suborder Cetancodonta, due to the misleading utilization of the suffix -morpha for a crown group, [6] as well as the risk of confusion with the clade Hippomorpha (which consists of equid perissodactyls); [7] however Whippomorpha ...
The traditional theory of cetacean evolution was that cetaceans were related to the mesonychian. These animals had unusual triangular teeth very similar to those of primitive cetaceans. This is why scientists long believed that cetaceans evolved from a form of mesonychian.