May 11, 2007 — The audio world of dinosaurs, especially larger species like
T. rex, was deep and low, according to new research on hearing in archosaurs, a group that includes birds, crocodiles, alligators and the extinct dinosaurs.
The discovery reveals how similar the ear anatomical structure is among living birds, crocodilians and their distant dino relatives.
The findings, which will be presented in June at the Acoustical Society of America Meeting in Utah, also suggest that dinosaurs produced noises that were similar to the sounds they could hear.
"As a general rule, animals can hear the sounds that they produce," lead author Robert Dooling told Discovery News.
Dooling is a professor of psychology and co-director of the Center for the Comparative and Evolutionary Biology of Hearing at the University of Maryland at College Park. He conducted the comparative study on archosaur ear data with German neuroanatomists Otto Gleich and Geoffrey Manley.
In addition to gathering inner ear measurements for living animals, the team took these same measurements from fossil remains of brachiosaurus, allosaurus and archeoptryx.
The researchers found that an animal’s body mass is significantly correlated to the size of the individual’s internal ear structure, which in turn is linked to what that creature could hear.
This determination allowed the scientists to extrapolate the hearing of the smallest bird, which weighs just around a third of an ounce, to that of huge dinos like brachiosaurus, which weighed 75 tons.
Dooling and his team believe hearing in such large dinosaurs was restricted to low frequencies with a high frequency limit below 3 kilohertz.
