Find out more about the fossil discovery
15 November 2011 Last updated at 17:29 GMT
The remains of dozens of ancient whales from seven million years ago have been discovered in North Chile.
A team found the skeletons of 15 whales in just 15 days.
The bones of sharks, dolphins and seals were also discovered.
It's the largest find of its kind in South America.
A lot of the fossils have complete skeletons which experts say will help them discover more about the mammals.