Dorudon atria. Illustration and photo-reconstruction of the ancient whale Dorudon swimming in search of pray; a sea turtle is passing by. Dorudon (spear-tooth) is a genus of extinct basilosaurid ancient whales that lived 40.4 to 33.9 million years ago, in the Eocene. They were about 5 metres long and fed on small fish and molluscs. Dorudon lived in warm seas around the world. Fossils have been found along the former shorelines of the Tethys Sea in present-day Egypt, Pakistan, the United States, New Zealand and Western Sahara.