Fossils unearthed in a South Carolina drainage ditch are providing insight into the development of ultrasonic hearing in prehistoric whales, a trait closely linked to their uncanny ability to hunt and navigate using sound waves and echoes.
“This was a small, toothed whale that probably used its remarkable sense of hearing to find and pursue fish, with echoes only,” explained study co-author Jonathan Geisler, an NYIT associate professor, in a statement.
High-frequency hearing capability is a necessary feature of all toothed whales, which use it in conjunction with echoes of their own calls in order to echolocate – using sound to map out their surroundings and navigate and seek food. Bats use it. So do dolphins.
“This would allow it to hunt at night,” said Geisler. “But, more importantly, it could hunt at great depths in darkness, or in very sediment-choked environments.”
The NYIT researchers say their study shows that most of the features for high-frequency hearing in the animals were in place 27 million years ago, around the same time that echolocation evolved. Some features might have even evolved earlier than that.
“Previous studies have looked at hearing in whales but our study incorporates data from an animal with a very complete skull,” said postdoctoral fellow Morgan Churchill, the lead author of the study.
“The data we gathered enabled us to conclude that it could hear at very high frequencies,” he noted, “and we can also say with a great degree of certainty where it fits in the tree of life for whales.”
Detailed findings about the new species and its hearing have been published in the journal Current Biology.
Maxine J. Martin