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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.
Cetacea (/ s ɪ ˈ t eɪ ʃ ə /; from Latin cetus 'whale', from Ancient Greek κῆτος 'huge fish, sea monster') [3] is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises.
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.
Cetacea (/ s ɪ ˈ t eɪ ʃ ə /; from Latin cetus 'whale', from Ancient Greek κῆτος 'huge fish, sea monster') is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises.
Whales do not form a clade or order; the infraorder Cetacea includes dolphins and porpoises, which are not considered whales in the informal sense. [citation needed] The phylogenetic tree shows the relationships of whales and other mammals, with whale groups [citation needed] marked in green.
These whales hunt by echolocation in deep water (where the majority of their prey is located) between about 200 and 1,885 m (656 and 6,184 ft) and usually catch about 30 prey per dive. Cuvier's beaked whales must forage on average at 1,070 m (3,510 ft) for 58 minutes and Blainville's beaked whales typically forage at 835 m (2,740 ft) deep for ...
The evolution of these sinuses also seems to have caused some restructuring of the skull base due to the development of bony walls surrounding the sinuses. The ectotympanic of all cetaceans, including Pakicetus and Ambulocetus , has a bony growth (involucrum) on the medial lip speculated to aid in the detection of low-frequency sounds.