for National Geographic News
Large dinosaurs' hearing was more sensitive to booms and thuds than squeaks and whistles, new research says.
Dinos such as Brachiosaurus and Allosaurus probably could hear the deep-toned sounds of other dinosaurs' footfalls from miles away, researchers say.
But these massive reptiles may have had little or no hearing at higher sound frequencies—suggesting that the squeals of a smaller animal facing a Tyrannosaurus rex may have literally fallen upon deaf ears.
The theory of how dinosaurs may have perceived sound comes from studies of hearing in birds, which are widely believed to be dinosaurs' closest living relatives.
(Related: "'Feathered' Dinosaur Was Bald, Not Bird Ancestor, Controversial Study Says" [June 1, 2007].)
"We know a lot about hearing in birds," said acoustics researcher Robert Dooling of the University of Maryland, College Park.
"Big birds hear better at low frequencies, and small birds hear better at high frequencies."
Dooling's latest work, in collaboration with two German scientists, suggests the relationship between size and hearing extends from tiny songbirds to the 75-ton (68-metric-ton) Brachiosaurus.
That's because the inner ear structure of all archosaurs—the group of related species that includes dinosaurs, birds, and crocodiles—is basically identical, the experts say.
"What makes this whole thing work is that the ears of dinosaurs and birds are all scale models of one another," Dooling said.
The scientist presented his team's findings this week at the annual meeting of the Acoustical Society of America in Salt Lake City, Utah.
SOURCES AND RELATED WEB SITES