The landmark finding represents a long-sought "missing link" in the 10m-year journey that saw ancient land mammals evolve into modern cetaceans, a group that includes whales, dolphins and porpoises.
Scientists have long known that whales are mammals whose ancient ancestors walked on land, but only in the past 15 years have they unearthed fossils that shed light on the creatures' dramatic evolutionary history. The latest discovery, named Indohyus, is the first whale ancestor known to have lived on land.
A near-complete skeleton of the animal was constructed, close in size to a domestic cat, dating from 48m years ago.
Storyteller : Hans Thewissen at the Northeastern Ohio Universities College of Medicine
How Bambi evolved into Mobi-Dick
Story Research : How Bambi gave rise to Mobi-Dick.