Sinus-Laden Dino Skulls Reveal Hotheaded Life

Dec. 9, 2008 -- A fully fleshed out Tyrannosaurus rex head may have weighed more than 1,100 pounds, but much of that volume was filled with air, according to a new study that suggests all dinosaurs were airheads.

Scientists have discovered that dinos possessed more air cavities in their heads than was previously believed, including many sinuses -- the same cavities that can lead to sinus headaches and infections in people.

"Dinosaurs likely suffered from nasty sinus infections," co-author Lawrence Witmer told Discovery News.

"In fact, we have other evidence that these infections spread to their bones, so dinosaurs could have suffered from painful, pounding headaches at times," added Witmer, a professor of paleontology at Ohio University's College of Osteopathic Medicine.

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He and colleague Ryan Ridgely CT scanned and 3-D imaged four dinosaur skulls: two fierce carnivores and two plant eaters. The meat eaters were T. rex and Majungasaurus, while the herbivores were represented by Panoplosaurus and Euoplocephalus, both ankylosaurian dinosaurs, which had armored bodies and short snouts.

The findings were recently published in The Anatomical Record.

"Scientists like myself tend to look at dinosaur brains, bones, eyeballs and such, but airway systems, essentially empty spaces in the skull, sort of slipped between the research cracks over the years and did not receive much attention," Witmer said.

The study revealed that predatory dinosaur heads featured large olfactory areas with an arching airway extending from the nostrils to the throat, along with the many sinus cavities. The air spaces made the skull bones hollow, similar to strong, yet lightweight, hollow beams used in construction work.

The analysis allowed the scientists to more accurately determine the weight of fleshed out dinosaur heads. Majungasaurus' head weighed around 70 pounds, but the 1,100-pound-plus head of T. rex took them aback.

"That's more than the combined weight of the whole starting lineup of the Cleveland Cavaliers," Witmer said.