Basilosaurus Skeleton on display in the Smithsonian MuseumLikewise, the Basilosaurus had a long flexible body for locomotion and stable neck to swim effectively. Blubber, blowholes and flukes are among the hallmarks of the roughly 80 species of cetaceans (whales, dolphins and porpoises) alive today. B. isis is slightly smaller than B. cetoides, with B. isis being 15–18 m (49–59 ft) long and B. cetoides being 17–20 m (56–66 ft) long. There was no straight-line march of terrestrial mammals leading up to fully aquatic whales, but an evolutionary riot of amphibious cetaceans that walked and swam along rivers, estuaries and the coasts of prehistoric Asia. Order: Cetacea Suborder: Archaeoceti. It was the top predator in the Tethys ocean during its existence. If the astragalus of an early archaeocete could be found it would provide an important test for both hypotheses.In 2001, archaeocetes possessing this bone were finally described, and the results were unmistakable. The Mesonychids were wolf-sized carnivores who scientists believe may have lost their terrestrial characteristics and went back to the marine environment, leading to whales.

In artiodactyls this bone has an immediately recognizable “double pulley” shape, a characteristic mesonychids did not share. The jaw contained teeth that differed in size and shape, a characteristic of mammals but not most reptiles. (From Fowler, O.S. Describe how otters swim, whales swim, and land mammals run? been of Some of the sediment attached to the bone contained small shells that showed that the large creature had once lived in an ancient sea, but little more could be said with any certainty.Bry’s donation was soon matched, and even exceeded, by that of Judge John Creagh from Alabama. What Vestigial structure did the basilosaurus have that modern whales do not? He asked for more bones, and Creagh soon sent parts of the skull, jaws, limbs, ribs, and backbone of the enigmatic creature. In addition, the Basilosaurus, which is a stage where the length of its hind legs has been reduced in earnest among the more evolved primitive whales, was judged to have been swimming by using its waist. In 2007, Thewissen and other collaborators announced that Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Basilosaurus (Basilosaurus Harlan, 1864). The skull of Even better, two jaw fragments showed that the teeth of Throughout the 1990s, the skeletons of more or less aquatically adapted ancient whales, or archaeocetes, were discovered at a dizzying pace. " It looked for all the world like a whale on diet pills! "

Mesonychids were not the ancestors of whales, and hippos are now known to be the closest living relatives to whales.Recently scientists determined which group of prehistoric artiodactyls gave rise to whales.

By 40 million years ago, Basilosaurus-- clearly an animal fully adapted to an aquatic environment -- was swimming the ancient seas, propelled by its sturdy flippers and long, flexible body. ‘Basilosaurus was a very strange animal, very long and snakelike,’ says Gingerich. Even more surprising was that comparisons of these proteins used to determine evolutionary relationships often placed whales This conflict between the paleontological and molecular hypotheses seemed intractable. The Rhodocetus, an early ancient whale from the middle Eocene, had short vertebrae to stabilize the neck for swimming. The bones were so numerous that in some fields they were destroyed because they interfered with cultivating the land.In 1832, a hill collapsed on the Arkansas property of Judge H. Bry and exposed a long sequence of 28 of the circular bones. www.prehistoric-wildlife.com. smithsonianmag.com By the turn of the 20th century the oldest fossil whales were still represented by While analyzing the relationships of ancient meat-eating mammals in 1966, however, the evolutionary biologist Leigh Van Valen was struck by the similarities between an extinct group of land-dwelling carnivores called mesonychids and the earliest known whales.