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Rodhocetus
''Rodhocetus'' (from ''Rodho'', the geological anticline at the type locality, and ''cetus'', Latin for whale) is an extinct genus of protocetid early whale known from the Lutetian () of Pakistan.〔. Retrieved September 2013.〕 The best-known protocetid, ''Rodhocetus'' is known from two partial skeletons that taken together give a complete image of an Eocene whale that had short limbs with long hands and feet that were probably webbed and a sacrum that was at immobile with four partially fused sacral vertebrae. It is one of several extinct whale genera that possess land mammal characteristics, thus demonstrating the evolutionary transition from land to sea.
==Description==
Throughout the 1990s, a close relationship between cetaceans and mesonychids, an extinct group of cursorial, wolf-like ungulates, was generally accepted based on morphological analyses. In the late 1990s, however, cladistic analyses based on molecular data clearly placed Cetacea within the Artiodactyla near the hippopotamus. One of the diagnostic characters of artiodactyls are 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 balochistanensis'', and these cetaceans all had double-pulley heel bones — the cladistic controversy was finally settled.
Through a principal components analysis demonstrated that ''Rodhocetus'' had trunk and limb proportions similar to the Russian desman, a foot-powered swimmer using its tail mainly as a rudder. From this Gingerich concluded that ''Rodhocetus'' was swimming mostly at the surface by alternate strokes of its hind feet, and that it was insulated by fur rather than blubber, as are ''Dorudon'' and modern cetaceans, which made it buoyant and incapable of deep diving.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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