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Female beaked whales' teeth are hidden in the gums and are not visible, and most male beaked whales have only two short tusks. Narwhals have vestigial teeth other than their tusk, which is present on males and 15% of females and has millions of nerves to sense water temperature, pressure and salinity.
Mysticetes are also known for their gigantism, as baleen whales are among the largest organisms to ever have lived; they reach lengths greater than 20 m and weigh more than 100,000 kg. [44] This gigantism is directly related to their feeding mechanism – mysticete size has been found to be dependent on the amount of baleen a mysticete can use ...
Baleen whales have two flippers on the front, near the head. Like all mammals, baleen whales breathe air and must surface periodically to do so. Their nostrils, or blowholes, are situated at the top of the cranium. Baleen whales have two blowholes, as opposed to toothed whales which have one.
Whales do, however, lack short wavelength sensitive visual pigments in their cone cells indicating a more limited capacity for colour vision than most mammals. [51] Most whales have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas and a tapetum lucidum; these adaptations ...
Then he advises what sort of Apes to make the choice of, as most resembling a Man : And conclude "One ought to know the Structure of all the Bones either in a Humane Body or in an Apes ; 'tis best in both ; and then to go to the Anatomy of the Muscles." [7] Up until that point, Galen and his teachings had been the authority on human anatomy ...
Whales and their relatives have a soft tissue flipper that encases most of the forelimb, and elongated digits with an increased number of phalanges. [9] Hyperphalangy is an increase in the number of phalanges beyond the plesiomorphic mammal condition of three phalanges-per-digit. [ 10 ]
Vestigial structures are often called vestigial organs, although many of them are not actually organs. Such vestigial structures typically are degenerate, atrophied, or rudimentary, [3] and tend to be much more variable than homologous non-vestigial parts. Although structures commonly regarded "vestigial" may have lost some or all of the ...
One of the diagnostic characteristics of artiodactyls is the double-pulley astragalus (heel bone), and palaeontologists, unconvinced by the data from the labs, set themselves out to find archaeocete single-pulley heel bones. Hind legs from three archaeocete species were recovered within a few years, among them those of Rodhocetus ...