Ancient whales have legs

Studies conducted today show the first whales in the ocean swim by waving their massive hind legs.

The new discovery sheds light on the mysterious transformation when these giant sea monsters leave their land life.

The ancestors of the whales used to stride with four feet on land like other mammals. Over time they evolved to be able to adapt to the water environment, the front legs turned into flippers while the hind legs and hips were dissipated. Although modern whales still carry traces of pelvis, hybrid whales are born with the characteristics of remnant limbs.

There are a lot of mysteries around how the first anatomical features of the female elephants can be modified to help them live in the water. An important piece to solve the mystery is the event of discovering the exact moment when the large lobes on their healthy tail form.

The vertebrate paleontologist Mark Uhen of the Alabama Museum of Natural History in Tuscaloosa explains: 'The origin of the lobes is one of the last steps in the transition from the above habitat. dried down under the sea '.

The swimming style of the tail of the horned whale (Mysticeti) and the modern (Odontoceti) whale evolved from the hip-shaking style of ancient Georgiacetus elephants.(Artwork: Mary Parrish, Smithsonian Institute)

To clarify the mystery, Uhen analyzed newly excavated fossil samples along the river bank in Alabama and Mississippi discovered by hunters of amateur bone fossils. Those bones were once of the ancient Georgiacetus whale, which lived along the Gulf Coast in North America about 40 million years ago - the time when most of Florida's area was submerged in seawater. Ancient whales have a length of 12 fut, they use sharp teeth to catch fish and squid for food.

The first whales with tail lobes are close relatives of Georgiacetus who lived 38 million years ago. But after about 2 million years Georgiacetus was separate from other lobed whales, Uhen now found that Georgiacetus did not seem to have a tail lobe. A new 2-inch long tail bone was discovered , out of 20 tail bones that an ancient whale had, not as flattened as the bones of a tail whale.

Instead, Uhen argued that Georgiacetus waved massive legs like a paddle to swim. Previous studies have also demonstrated that this ancient whale has large hips, thus showing that it also has very large hind legs. Strangely, scientists also discovered that its pelvis is not attached to the spine. This means that its hind legs cannot paddle in the water or support body weight while on land. This is the unresolved puzzle until today.

Uhen told LiveScience: 'We tried to verify that the ancient whale had to shake its hips to swim, helping to move its legs like a paddle. So it swims quite like a modern whale, it must bend to lift its body up and down. '

Scientists have published their findings on the latest issue of the Journal of Vertebrate Paleontology.