The whale is descended from a deer-like animal that lived 48 million years ago, according to fossil evidence.

Remains found in the Kashmir region of India suggest the fox-sized mammal is the long-sought land-based ancestor of whales, dolphins and porpoises.

Research in Nature suggests the animal lived mainly on land but dived into water to escape predators.

Whales are known to be descended from land-dwellers but the "missing link" has been a mystery until now.

Although Indonyus, as it is known, looks nothing like the whales of today, it shares certain anatomical features.

The structures of its skull and ear are similar to those of early whales, and like other animals that spend a lot of time in water, it had thickened bones that provided ballast to keep its feet anchored in shallow water.

"We've found the closest extinct relative to whales and it is closer than any living relative," said study leader Professor Hans Thewissen of the Department of Anatomy at Northeastern Ohio Universities College of Medicine in Ohio, US.

Full report on BBC News Online

Very interesting.  Thanks for passing this along.