The marine mammals known as cetaceans originated about 50 million years ago in south Asia, but their terrestrial ancestor is something of a mystery. Hans Thewissen and colleagues now provide the missing Eocene piece of the jigsaw.
The marine mammals known as cetaceans originated about 50 million years ago in south Asia, but their terrestrial ancestor is something of a mystery. Hans Thewissen and colleagues now provide the missing Eocene piece of the jigsaw.