Fossil evidence suggests that the first whales could detect high-frequency sounds.

Credit: Curr. Biol.

Researchers have debated whether animals called archaeocetes — the common ancestors of all modern whales and dolphins — specialized in hearing high frequencies, like modern killer whales, or low frequencies, like today's humpback whales. Morgan Churchill at the New York Institute of Technology in Old Westbury and his colleagues describe a new species of whale (fossil skull pictured) dating from 27 million to 24 million years ago. Features of its remarkably well-preserved inner ear, as well as other structures, suggest that the animal could generate and hear high-frequency sounds. The inner ear also has primitive features similar to those of archaeocetes.

The authors suggest that the first whales could hear higher frequencies than their terrestrial ancestors — an ability co-opted by later toothed whales for echolocation.

Curr. Biol. http://doi.org/bnh5 (2016)