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Sinus-Laden Dino Skulls Reveal Hotheaded Life

Jennifer Viegas, Discovery News

The heads of the plant-eating dinosaurs were lighter, but they featured twisty corkscrewed air passageways that Witmer likened to "crazy straws," the swirly drinking straws favored by kids.

One function of this complex network of nasal cavities was heat transfer, the researchers believe, since blood vessels ran alongside their nasal passages, allowing air to pass over the moist surfaces, cooling the blood and therefore removing excess heat from their heads.

"Most big dinosaurs would have had a problem of being too hot," Witmer said. "We now think these were warm blooded animals. You can imagine them sitting out under the Cretaceous sun."

"They created shade, but didn't often find it," he added.

The scientists also believe the nasal passages acted as resonating chambers, giving each dino its own unique "voice." It's possible that armored dinosaurs, in particular, could recognize individuals based on their vocalizations alone.

CT scans of crocodiles and ostriches found similar -- although not quite so prominent -- head air spaces, adding to the evidence that these creatures are distantly related to dinosaurs. Their collective common ancestor must have passed down the trait.

Michael Ryan, coordinator of research and head of vertebrate paleontology at the Cleveland Museum of Natural History, told Discovery News that Witmer's lab has "been the cutting edge for investigating what's going on inside of the fossil dinosaur skulls that we so painstakingly dig up."

"The new information about the convoluted nasal passages of ankylosaurs gives us the very first suggestion that these weird herbivorous dinosaurs may have had complex vocal patterns," Ryan said. "It turns out that the Late Cretaceous may have been as noisy as a frog pond during mating season, with the air being full of honks, chirps and squeaks."

Ryan added, "It's work like this that helps us to better understand these dinosaurs as once living animals."

Related Links:

Jennifer Viegas' Blog: Born Animal

Royal Tyrrell Museum

How Stuff Works: Dinosaurs