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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.
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 ...
A phylogenetic tree showing the relationships among cetacean families. (from Evolution of cetaceans) Bowhead ...
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 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.
Here's how to distinguish "sundowning"—agitation or confusion later in the day in dementia patients—from typical aging, from doctors who treat older adults.
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 ...