NEET BIOLOGY

Detailed explanation-1: -Although whales are expert swimmers and perfectly adapted to life underwater, these marine mammals once walked on four legs. Their land-dwelling ancestors lived about 50 million years ago.

Detailed explanation-2: -Over time, as they evolved to dwell in water, their front legs became flippers while they lost their back legs and hips, although modern whales all still retain traces of pelvises, and occasionally throwbacks are born with vestiges of hind limbs.

Detailed explanation-3: -Scientists excavating fossil bones from an ancient seabed in Egypt have found the first evidence that primitive whales had functional legs, complete with kneecaps, ankles and little toes, according to research published today. Researchers have long suspected ancient whales once had legs.

Detailed explanation-4: -Both hippos and whales evolved from four-legged, even-toed, hoofed (ungulate) ancestors that lived on land about 50 million years ago. Modern-day ungulates include hippopotamus, giraffe, deer, pig and cow.