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Basilosaurids, which had tiny hind limbs and flipper-shaped fore limbs, were obligatorily aquatic and came to dominate the oceans. They still lacked the echolocation and baleen of modern odontocetes and mysticeti. [7] Basilosaurids and dorudontids are the oldest obligate aquatic cetaceans for which the entire skeleton is known.
A stranding is when a cetacean leaves the water to lie on a beach. In some cases, groups of whales strand together. The best known are mass strandings of pilot whales and sperm whales. Stranded cetaceans usually die, because their as much as 90 metric tons (99 short tons) body weight compresses their lungs or breaks their ribs. Smaller whales ...
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.
Anatomy of the bottlenose dolphin Features of a sperm whale skeleton. Toothed whales have torpedo-shaped bodies with usually inflexible necks, limbs modified into flippers, no outer ears, a large tail fin, and bulbous heads (with the exception of the sperm whale family). Their skulls have small eye orbits, long beaks (with the exception sperm ...
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.
Ambulocetus (Latin ambulare "to walk" + cetus "whale") is a genus of early amphibious cetacean [a] from the Kuldana Formation in Pakistan, roughly 48 or 47 million years ago during the Early Eocene . It contains one species, Ambulocetus natans (Latin natans "swimming"), known solely from a near-complete skeleton.
The earliest known ancestor of arctic whales is Denebola brachycephala from the late Miocene around 9–10 million years ago. [55] A single fossil from Baja California indicates the family once inhabited warmer waters. [27] [56] [57] Acrophyseter skull. Ancient sperm whales differ from modern sperm whales in tooth count and the shape of the ...
Zygorhiza, mounted skeleton. Basilosaurids ranged in size from 4 to 16 m (13 to 52 ft) and were fairly similar to modern cetaceans in overall body form and function. [7] Some genera tend to show signs of convergent evolution with mosasaurs by having long serpentine body shape, which suggests that this body plan seems to have been rather ...