Whale Ancestors Echolocated 28 Million Years Ago

An ancient whale used sound beams to navigate and stalk prey 28 million years ago, an analysis of a new fossil suggests.

The new whale species, called Cotylocara macei, contains air pockets in the skull similar to those used by porpoises and dolphins to send out focused sound beams. The discovery pushes back the origins of the ability, called echolocation, to at least 32 million years ago, said study co-author Jonathan Geisler, an anatomist at the New York Institute of Technology.

The skull of the ancient whale C. macei, reveals distinctive density variation and shapes suggestive of echolocation. James Carew and Mitchell Colgan

"It suggest echolocation evolved very, very early in the history of the group that involved toothed whales," a group that includes sperm whales and killer whales, as well as dolphins and porpoises, Geisler said. [Image Gallery: Russia's Beautiful Killer Whales]

The ancient whale, which was about 28 million years old, grew to about 10 feet (3 meters) long and looked somewhat similar to modern-day dolphins or small cetaceans, though they are not closely related. It likely lived in shallow marine environments, such as the mouth of an estuary or a little further offshore, Geisler said.

Early echolocationC. macei also had several distinctive features, including bone density variations and several deep air cavities, including one on top of the skull and one on either side of the base of the snout, Geisler said.

The ear bones and soft tissue from the whale weren't preserved, so they don't know for sure how the whale's echolocation would have sounded or how it processed the reflections from sound beams they sent out, Geisler said.

The new discovery suggests that echolocation evolved very early in whale evolution, likely soon after odontocetes diverged from the ancestors of baleen whales.

The findings were published today (Mar. 12) in the journal Nature.

- Tia Ghose, LiveScience

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