How armour-plated dinosaurs developed their own air-con

A virtual model of the skull of Euoplocephalus tutus shows how air flow through through this dinosaur's convoluted nasal passages cooled the blood headed to the brain.

Armour-plated dinosaurs – ankylosaurs – used their long, winding nasal passages as heat transfer devices to manipulate their body temperature, palaeontologists have discovered.

Modern mammals and birds use scroll-shaped bones called conchae or turbinates to warm inhaled air, but ankylosaurs used a different anatomical construction.

Palaeontologist Jason Bourke and his team of scientists at Ohio University discovered the technique after using CT scans to document the anatomy of nasal passages in two different ankylosaur species.

"There are two ways that animal noses transfer heat while breathing," says Bourke. "One is to pack a bunch of conchae into the air field, like most mammals and birds do – it's spatially efficient. The other option is to do what lizards and crocodiles do and simply make the nasal airway much longer. Ankylosaurs took the second approach to the extreme."

Bourke modelled airflow through 3D reconstructions of these tubes and found that the convoluted passageways would have given the inhaled air more time and more surface area to warm up to body temperature by drawing heat away from nearby blood vessels.

As a result, the blood would be cooled before flowing to the brain to keep its temperature stable.

Lawrence Witmer, who was also involved with the study, said:

Our team discovered these "crazy-straw" airways several years ago, but only recently have we been able to scientifically test hypotheses on how they functioned. By simulating airflow through these noses, we found that these stretched airways were effective heat exchangers. They would have allowed these multi-tonne beasts to keep their multi-ounce brains from overheating.

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