Dinosaurs' nasal passages kept their brains cool

The large size and shape of nasal passages in dinosaurs would have allowed incoming air to cool the blood making its way to the brain, maintaining the brain at an optimum temperature, a new study has found.

Dinosaurs possessed among the largest and most complex nasal passages seen in animals and their function has puzzled paleontologists.

"My work represents the first test of the hypothesis that the elaborated nasal passages of large dinosaurs functioned as efficient heat exchangers," said Jason Bourke, doctoral student researcher at Ohio University and lead author of the study.

Using a branch of engineering known as computational fluid dynamics, Bourke simulated the movement of air and heat through the nasal passages of various dinosaur species.

Detailed reconstruction of the 3-dimensional shape of the nasal passages in dinosaurs showed that large dinosaurs, whose bodies would have held on to more heat than smaller-bodied animals, needed elaborate and specialised nasal passages to avoid overheating their brains, 'phys.org' reported.

"For most dinosaurs that I looked at, there would have been a substantial amount of physiologically active soft tissues in their noses," said Bourke.

"This strongly suggests that dinosaur airways were more than capable of changing the attributes of respired air," Bourke said.

These findings provide an answer to the mystery of how dinosaurs avoided having their large bodies overheat their small brains, a question that has plagued paleontologists reconstructing dinosaur physiology.

"By having this blood detour through the nasal passages and dump some of that excess heat before reaching the brain, dinosaurs were able to keep their brains at an optimum temperature for their bodies," said Bourke.

The study was presented at the 75th Annual Meeting of the Society of Vertebrate Paleontology in Dallas, Texas.