Whales May Have Evolved from Raccoon-sized Creature

Prior molecular studies have proposed the hippo as the closest land relative of today's whales, but researchers reporting in the journal Nature on Wednesday suggest a four-footed creature from India known as Indohyus, which probably hid in water in times of danger.

Scientists have long known that whales had ancestors that walked on land. Now a team lead by Hans Thewissen of Northeastern Ohio Universities Colleges of Medicine and Pharmacy have pieced together a series of intermediate fossils that trace the whale's evolutionary journey from land to sea.

Thewissen and his team studied the structure and composition of hundreds of fossils of Indohyus, which is part of the larger group known as raoellids. Raoellids lived at about the same time as the earliest whales -- about 50 million years ago.

Thewissen's team found key similarities in the skull and ear that suggest a link to cetaceans, a family that includes whales, dolphins and porpoises.