When did marine mammals develop echolocation?
DOI: 10.1063/PT.5.027759
Science : While it is known that modern whales, dolphins, and porpoises use echolocation to hunt and navigate, no one knows exactly when that ability evolved. Now Jonathan Geisler of the New York Institute of Technology College of Osteopathic Medicine and colleagues present evidence that the ability may date back to at least the Oligocene epoch, some 28 million years ago. While studying the skull of a fossil whale, dubbed Cotylocara macei, that was found in South Carolina, the researchers discovered cavities at the base of the snout and on top of the skull, which probably held air sinuses. Such air sinuses are thought to be important in the production of high-frequency sounds. To determine whether ancient whales could have heard the sounds, however, more research is needed, particularly on the structure of their inner ear.
