Date:
August 4, 2016
Source:
Cell Press
All
living toothed whales rely upon echoes of their own calls to navigate and hunt
underwater, a skill that works best in conjunction with high-frequency hearing.
Now, researchers reporting in the Cell Press journal Current Biology on August 4 who studied one of the
best-preserved ears of any ancient whale ever discovered find that whales'
high-frequency hearing abilities arose earlier than anticipated.
"Our
study suggests that high-frequency hearing may have preceded the emergence of
echolocation," says Morgan Churchill of New York Institute of Technology
in Old Westbury, New York.
Churchill
and his colleagues made their discovery in studies of a new fossil whale
species (Echovenator sandersi) found
in a drainage ditch in South Carolina. The researchers CT scanned the ancient
whale's remarkably complete fossilized ear and compared it to those of two
hippos and 23 fossil and living whales. Those analyses uncovered many features
found today in dolphins, which can hear at ultrasonic frequencies.
The
anatomy of Echovenator's ear suggests that high-frequency hearing evolved early
in whale evolution, about 27 million years ago and that traits associated with
this ability actually predate the emergence of toothed whales. It also suggests
that the evolutionary ancestors of toothed whales could hear at higher
frequencies than their relatives on land.
Churchill
says that the inner ear of Echovenator is surprisingly similar to that of
modern whales. In fact, only one trait of the ancient whale's ear was more
similar to primitive whales than to modern whales, suggesting a very rapid
evolution of hearing abilities in early whales.
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