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Thursday, 8 November 2007 Jennifer Viegas
Discovery News

Dinosaurs had a similar breathing mechanism to modern diving birds, like penguins(Source: iStockphoto)

Meat-loving dinosaurs didn't huff and puff while chasing their prey, according to a new study that concludes dinosaur breathing was smooth, like that of present-day diving birds.

The study, published today in the Proceedings of the Royal Society B: Biological Sciences, presents the first explanation for how carnivorous dinosaurs breathed.

The researchers also believe large herbivorous dinosaurs, such as Diplodocus and Brachiosaurus, also breathed like birds.

"Dinosaurs probably possessed a breathing mechanism that functioned like bellows," says lead author Dr Jonathan Codd, from the Faculty of Life Sciences at the University of Manchester.

"It would have operated smoothly, allowing them to chase after prey at around [65 kilometres per hour] without running out of breath."

Codd and his team studied the fossilised remains of maniraptoran dinosaurs, such as Oviraptor philoceratops, Velociraptor mongoliensis and the tiny Microraptor zhaoianus.

He and his colleagues also looked at fossils of extinct birds from the dinosaur era, including the most primitive known bird, Archaeopteryx, as well as bones from modern birds and crocodiles.

The scientists focused on tiny bones called 'uncinate processes', which play an important role in how modern birds breathe.

Breathing through the nose

Birds breathe with their mouths closed, with air travelling through the nasal cavity before filling the lungs and multiple air sacs.

Air can flow in and out due to moving bones, including the uncinate processes, which help to push the ribs outward, expanding the chest. If a bird couldn't move its ribs, it would suffocate.

Dinosaurs, like modern birds and crocodiles, were found to have the tiny, L-shaped uncinate processes that act as levers, moving the ribs and sternum in and out.

Efficient breathing

Diving birds and dinosaurs were found to have especially long levers, indicating very efficient breathing.

"At first, nobody even knew what role these structures played in modern birds," Codd says.

"They're small and not particularly exciting to look at, so many people commonly misidentified them as rib bones poking out from the bird's back."

Like a trained singer

Since the dinosaur levers would have also pumped their abdomens full of air, dinosaurs also probably had the breath power of a trained singer who tries to fill his or her entire body, especially the abdomen, with air.

A big difference, however, is that dinosaurs would have had two exhalations for every inhalation, in contrast to our single 'breathe in, breathe out' pattern, says Codd.

Professor David Carrier, an expert on bird and mammal breathing and locomotion from the University of Utah, says the researchers could be right.

"The function of uncinate processes, as proposed by Codd and collaborators, clearly could have facilitated the hypothesised ... breathing mechanism of theropod dinosaurs."

Bad breath?

Dinosaurs may have had respiratory systems similar to fowls, but did they have foul breath?

"It's quite likely," says Codd. "They possessed multiple teeth that would have trapped bits of rotting meat."

Story and image courtesy of ABC.net Science @
http://www.abc.net.au/science/articles/2007/11/08/2092731.htm?site=science&topic=health