Nose job for dinosaurs

T. rex's nostrils: High or low?
Image: Science

By BBC News Online's Ivan Noble

Working out what a dinosaur looked like is a difficult business when all there is to go on are its fossilised bones.

Biologically it'll make a huge difference for all kinds of dinosaurs

Lawrence Witmer
Ohio University

Locating crucial features like nostrils has been intelligent guesswork.

Now, a US-based scientist says the traditional assumption that dinosaurs had their nostrils high on their heads is wrong.

"We... found an extraordinary amount of evidence to suggest the nostrils of dinosaurs actually were parked out front," said Lawrence Witmer, of Ohio University.

Modern relatives

Dr Witmer examined modern-day relatives of dinosaurs to find characteristic markings etched into their bones by their soft tissues.

Old and new views of Diplodocus
Image: Science

By comparing these "signatures" with similar markings on dinosaur fossils, he was able to map the likely positions of the cartilage, blood vessels and other soft tissues making up a dinosaur's nasal cavity.

He looked at 62 animals from 45 species of crocodile, bird and lizard before reaching the conclusion that dinosaur nostrils were more likely to have been on the front of their heads.

Aquatic assumptions

Palaeontologists in the 19th Century assumed that giant sauropods like the long-necked brontosaur must have lived in water because they were as big as whales.

And if they lived in water, they probably had nostrils high on their forehead to allow them to breathe while partially submerged.

"Despite the fact that many years later we realised sauropods weren't primarily aquatic, we never addressed the nostril position again," said Dr Witmer.

"And somehow, we translated that nostril position to other dinosaurs," he said.

Evolutionary advantage

Dinosaurs would have had good reasons for having nostrils at the front of their heads, he said.

Having nostrils closer to their mouths would have made physiological sense for creatures relying on scent to find mates, detect predators and find food, Dr Witmer said.

He found the largest nasal passages in horned dinosaurs like Triceratops, duck-billed dinosaurs, and brontosaurs like the 40-tonne Diplodocus.

Dr Witmer's work is published in the journal Science.