ONE of the first mammals to use echolocation may not have been a bat or a whale, but an early ancestor of horses.
was a weasel-like ungulate that lived 55 million years ago, around the time that bats evolved echolocation.
of Montpellier University, France, and colleagues say that a new fossil cast of its braincase shows Hyopsodus had a large , a brain region enlarged in echolocating animals (PLoS One, ).
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They argue that Hyopsodus could echolocate, but at Duke University in Durham, North Carolina, says the large inferior colliculus may just be a sign of sensitive hearing.