Dorudon (Greek for "spear-toothed"); pronounced DOOR-ooh-don
Seashores of North America, northern Africa and the Pacific Ocean
Late Eocene (41-33 million years ago)
Size and Weight:
About 16 feet long and half a ton
Fish and mollusks
Small size; distinctive teeth; nostrils on top of head; lack of echolocation abilities
For years, experts believed that the scattered fossils of the prehistoric whale Dorudon actually belonged to juvenile specimens of Basilosaurus, one of the largest cetaceans that ever lived. Then, the unexpected discovery of unmistakably juvenile Dorudon fossils demonstrated that this short, stubby whale merited its own genus--and may actually have been preyed on by the occasional hungry Basilosaurus, as evidenced by bite marks on some preserved skulls. (This scenario was dramatized in the BBC nature documentary Walking with Beasts, which portrayed Dorudon juveniles being gobbled up by their larger cousins).
One thing that Dorudon shares in common with Basilosaurus is that both of these Eocene whales lacked the ability to echolocate, since neither of them possessed a characteristic "melon organ" (a mass of soft tissues that acts as a kind of lens for sound) in their foreheads. This adaptation appeared later in cetacean evolution, spurring the appearance of larger and more diverse whales that subsisted on a wider variety of prey (Dorudon, for instance, had to content itself with presumably slow-moving fish and mollusks).