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It is divided into toothed whales (Odontoceti) and baleen whales (Mysticeti), which diverged from each other in the Eocene some 50 million years ago (mya). Cetaceans are descended from land-dwelling hoofed mammals, and the now extinct archaeocetes represent the several transitional phases from terrestrial to completely aquatic. [1]
Though it was known that cetaceans descended from land mammals before the discovery of Ambulocetus, the only evidence of this in the fossil record was the 52-million-year-old (fully terrestrial) Pakicetus and the Paleocene mesonychians (as there was a hypothesised link between cetaceans and mesonychians). The limbs of more aquatic Eocene ...
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.
Whales evolved from land-living mammals, and must regularly surface to breathe air, although they can remain underwater for long periods of time. Some species, such as the sperm whale, can stay underwater for up to 90 minutes. [2] They have blowholes (modified nostrils) located on top of their heads, through which air is taken in and expelled.
It is possible that some protocetids had flukes. However, it is clear that they were adapted even further to an aquatic life-style. In Rodhocetus, for example, the sacrum (a bone that, in land-mammals, is a fusion of five vertebrae that connects the pelvis with the rest of the vertebral column) was divided into loose vertebrae. However, the ...
It was a wolf-like mammal, [3] about 1–2 m (3 ft 3 in – 6 ft 7 in) long, [4] and lived in and around water where it ate fish and other animals. The name Pakicetus comes from the fact that the first fossils of this extinct amphibious whale were discovered in Pakistan .
Drone videos of gray whales off Oregon have revealed new details about how the marine mammals find food. The findings were described in studies this summer. Drone video of gray whales offers new ...
The sperm whale or cachalot (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator.It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.