Родокет: Ертедегі киттер эволюциясының дәлелі

Genus of mammals

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. 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 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.

Rodhocetus was a small whale measuring long. Throughout the 1990s, a close relationship between cetaceans and mesonychians, 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 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 balochistanensis, and all three had double pulley heel bones, thus settling the cladistic controversy. 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.