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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 ...
Unlike all later cetaceans, it had four fully functional long legs. Pakicetus had a long snout; a typical complement of teeth that included incisors, canines, premolars, and molars; a distinct and flexible neck; and a very long and robust tail. As in most land mammals, the nose was at the tip of the snout. [5]
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.
Whales have two flippers on the front, and a tail fin. These flippers contain four digits. Although whales do not possess fully developed hind limbs, some, such as the sperm whale and bowhead whale, possess discrete rudimentary appendages, which may contain feet and digits.
Pakicetids have long thin legs, with relatively short hands and feet which suggest that they were poor swimmers. [1] To compensate for that, their bones are unusually thick (osteosclerotic), which is probably an adaptation to make the animal heavier to counteract the buoyancy of the water. [7]
Pitman, who has studied killer whales in Antarctica for over 10 years, said there's a similar divide between mammal- and fish-eating killer whales in those waters.
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
Scientists think they might have finally learned the secret to how whales sing their complicated songs. We knew whales made a vast array of vocalizations, called songs, that can carry for ...