A University of Maryland biologist has found that alligators map the location of sound the way birds do, suggesting the hearing strategy existed in their common ancestor, the dinosaurs.
Animal brains determine where a sound is coming from by analyzing the tiny difference in time it takes audio waves to reach each ear—a cue known as interaural time difference. Scientists have known that birds are exceptionally good at creating neural maps to chart the location of sounds, but little was known about how alligators process interaural time difference.
The new study of American alligators found that the reptiles form neural maps of sound in the same way birds do. The research by Catherine Carr, a Distinguished University Professor of biology at Maryland, and Lutz Kettler from the Technische Universität München was published last week in the Journal of Neuroscience.
To study how alligators identify where sound comes from, the researchers anesthetized 40 American alligators and fitted them with earphones. They played tones for the sleepy reptiles and measured the response in a part of the brain that is the seat of auditory signal processing. Their results showed that alligators create neural maps very similar to those previously measured in barn owls and chickens.
“We know so little about dinosaurs,” Carr said. “Comparative studies such as this one, which identify common traits extending back through evolutionary time, add to our understanding of their biology.”
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