The first whales once swam the seas by wiggling large hind feet, research now suggests.

These new findings shed light on the mysterious shift these leviathans made away from land.

The ancestors of whales once strode on land on four legs, just as other mammals do. 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.