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The aquatic lifestyle of cetaceans first began in the Indian subcontinent from even-toed ungulates 50 million years ago, with this initial stage lasting approximately 4-15 million years. [8] Archaeoceti is an extinct parvorder of Cetacea containing ancient whales.
Cetaceans are famous for their high intelligence, ... Whales' direct lineage began in the early Eocene, around 55.8 million years ago, with early artiodactyls. [73]
Cetaceans are famous for their high intelligence, complex social behaviour, and the enormous size of some of the group's members. For example, the blue whale reaches a maximum confirmed length of 29.9 meters (98 feet) and a weight of 173 tonnes (190 short tons), making it the largest animal ever known to have existed.
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 .
The family Balaenidae, the right whales, contains two genera and four species. All right whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; and long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes.
Basilosauridae is a family of extinct cetaceans. They lived during the middle to the early late Eocene and are known from all continents, including Antarctica. [1] [2] They were probably the first fully aquatic cetaceans. [3] [4] The group is noted to be a paraphyletic assemblage of stem group whales [5] from which the monophyletic Neoceti are ...
The limbs of more aquatic Eocene cetaceans did not preserve very well. Ambulocetus demonstrated that cetaceans swam by flexing the spine up and down (undulation) before they had evolved the tail fluke, forelimb propulsion evolved relatively late, and that cetaceans went through an otter-like phase with spinal undulation and hindlimb propulsion ...
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