December 8, 2008

Study: Dinosaurs had big head air cavities

U.S. scientists using computerized tomography scanning have found dinosaurs had much larger air cavities in their heads than had been thought.

Ohio University Professor Lawrence Witmer and research associate Ryan Ridgely examined skulls from two predators, Tyrannosaurus rex and Majungasaurus, as well as two ankylosaurian dinosaurs, Panoplosaurus and Euoplocephalus. For comparison, the scientists said they also studied scans of crocodiles and ostriches, which are modern day relatives of dinosaurs, as well as humans.

The analysis of the predatory dinosaurs revealed large olfactory areas, an arching airway that went from the nostrils to the throat and many sinuses. Overall, the scientists said, the amount of air space was much greater than the brain cavity.

Witmer and Ridgely also calculated the volume of the bone, air space, muscle and other soft tissues to make an accurate estimate of how much the heads weighed when the animals were alive. They determined a fully fleshed-out T. rex head, for example, weighed more than 1,100 pounds.

Witmer suggests the air spaces helped lighten the load of the head, making it about 18 percent lighter than it would have been.

The research appeared in a recent issue of the journal The Anatomical Record.