Airhead: The head of Tyrannosaurus rex (pictured) was filled with sinuses, says researchers, while the armored dinosaur Euoplocephalus had a "crazy-straw" nasal passage.
Credit: Witmer & Ridgely, Ohio University.
SYDNEY: Some predatory and armoured dinosaurs had more space in their skulls for air than for brains, says a new study, helping explain how some were able to support such massive heads.
The research, published in The Anatomical Record journal, reports that the heads of the ancient carnivores Tyrannosaurus rex and Majungasaurus, and armoured ankylosaur dinosaurs called Panoplosaurus and Euoplocephalus are likely to have been far lighter than previous anatomical work suggested.
Light and airy
"They were literally airheads," said Lawrence Witmer, palaeontologist and anatomist at Ohio University in Athens, USA.
"I've been looking at sinuses for a long time, and indeed people would kid me about studying nothing; looking at the empty spaces in the skull. But what's emerged is that these air spaces have certain properties and functions," he said.
Witmer's team has carried out much research, using computer models and anatomical comparisons to modern species, in order to reconstruct the features of dinosaurs such as their skeletons, muscles, blood vessels and nerves. But it turns out the air spaces between these tissues also tell an important part of the story.
The researchers used CT-scans (computed tomography) and virtual three-dimensional (3-D) reconstructions of dinosaur skull fossils to learn more about the nasal, sinus and brain cavities of the ancient animals.
Strong, light girders
Computers were then used to build detailed pictures of the inside of the heads, based on clues in the skull bones (such as the imprint of the brain on the shape of the skull), and the results were compared with this sinus structure of crocodiles, ostriches and humans. Birds and crocodiles are the two living groups of animals most closely related to dinosaurs.
The study demonstrated that the sinuses of the predatory dinosaurs were hollowed-out bones working as strong, light girders to support the architecture of their heads. The armoured ankylosaurs also had bizarrely twisted sinus systems.
The results have implications for our understanding of how dinosaurs vocalised and coped with overheating, said Witmer, whose work has already showed that airspaces may have been important for communication in duck-billed hadrosaurs.
Airheads
"Dinosaurs were airheads, literally" Obviously Democrats.