Meat-eating dinosaur from Argentina had bird-like breathing system

Sep 29, 2008
Flesh rendering of the predator Aerosteon with the body wall removed to show a reconstruction of the lungs (red) and air sacs (other colors) as they might have been in life. Drawing: Todd Marshall c 2008, courtesy of Project Exploration.

The remains of a 30-foot-long predatory dinosaur discovered along the banks of Argentina's Rio Colorado is helping to unravel how birds evolved their unusual breathing system.

University of Michigan paleontologist Jeffrey Wilson was part of the team that made the discovery, to be published Sept. 29 in the online journal Public Library of Science ONE and announced at a news conference in Mendoza, Argentina.

The discovery of this dinosaur builds on decades of paleontological research indicating that birds evolved from dinosaurs.

Birds have a breathing system that is unique among land animals. Instead of lungs that expand, birds have a system of bellows, or air sacs, which help pump air through the lungs. This novel feature is the reason birds can fly higher and faster than bats, which, like all mammals, expand their lungs in a less efficient breathing process.

Wilson was a University of Chicago graduate student working with noted dinosaur authority Paul Sereno on the 1996 expedition during which the dinosaur, named Aerosteon riocoloradensis ("air bones from the Rio Colorado") was found. Although the researchers were excited to find such a complete skeleton, it took on even more importance as they began to understand that its bones preserved hallmark features of a bird-like respiratory system.

Arriving at that understanding took some time. Laboratory technicians spent years cleaning and CT-scanning the bones, which were embedded in hard rock, to finally reveal the evidence of air sacs within Aerosteon's body cavity. Previously, paleontologists had found only tantalizing evidence in the backbone, outside the cavity with the lungs.

Wilson worked with Sereno and the rest of the team to scientifically describe and interpret the find. The vertebrae, clavicles, and hip bones bear small openings that lead into large, hollow spaces that would have been lined with a thin layer of soft tissue and filled with air in life. These chambers result from a process called pneumatization, in which outpocketings of the lungs (air sacs) invade the bones. Air-filled bones are the hallmark of the bellows system of breathing in birds and also are found in sauropods, the long-necked, long-tailed, plant-eating dinosaurs that Wilson studies.

"In sauropods, pneumaticity was key to the evolution of large body size and long necks; in birds it was key to the evolution of a light skeleton and flight," Wilson said. "The ancient history and evolutionary path of this feature is full of surprising turns, the explanations for which must account for their presence in a huge predator like Aerosteon and herbivores like Diplodocus, as well as in a chicken."

In the PLoS ONE paper, the team proposes three possible explanations for the evolution of air sacs in dinosaurs: development of a more efficient lung; reduction of upper body mass in tipsy two-legged runners; and release of excess body heat.

Sereno, a National Geographic Explorer-in-Residence, said he is especially intrigued by heat loss, given that Aerosteon was likely a high-energy predator with feathers but without the sweat glands that birds possess. At approximately 30 feet in length and weighing as much as an elephant, Aerosteon might well have used an air system under the skin to rid itself of unwanted heat.

Source: University of Michigan

Explore further: Ancient clay seals may shed light on biblical era

add to favorites email to friend print save as pdf

Related Stories

A/C came standard on armored dinosaur models

Nov 08, 2014

Sweating, panting, moving to the shade, or taking a dip are all time-honored methods used by animals to cool down. The implicit goal of these adaptations is always to keep the brain from overheating. Now a new study shows ...

Bone chemistry reveals royal lifestyle of Richard III

Aug 17, 2014

A recent study by the British Geological Survey, in association with researchers at the University of Leicester, has delved into the bone and tooth chemistry of King Richard III and uncovered fascinating ...

World's largest-ever flying bird identified

Jul 07, 2014

Scientists have identified the fossilized remains of an extinct giant bird that could be the biggest flying bird ever found. With an estimated 20-24-foot wingspan, the creature surpassed size estimates based ...

Recommended for you

Ancient clay seals may shed light on biblical era

Dec 20, 2014

Impressions from ancient clay seals found at a small site in Israel east of Gaza are signs of government in an area thought to be entirely rural during the 10th century B.C., says Mississippi State University archaeologist ...

Digging up the 'Spanish Vikings'

Dec 19, 2014

The fearsome reputation of the Vikings has made them the subject of countless exhibitions, books and films - however, surprisingly little is known about their more southerly exploits in Spain.

Short-necked Triassic marine reptile discovered in China

Dec 17, 2014

A new species of short-necked marine reptile from the Triassic period has been discovered in China, according to a study published December 17, 2014 in the open-access journal PLOS ONE by Xiao-hong Chen f ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

jeffsaunders
5 / 5 (1) Sep 29, 2008
well well well.

Evolution in action in multiple scenarios too. Just shows that there is more than one road to Rome and maybe the anti-evolution pro creationists will finally have to admit that the world was not actually created 6,000 years ago.

Then again maybe this will just prove that if you believe that (the creationist theory) you will believe whatever the hell you want.
D666
not rated yet Sep 30, 2008
maybe the anti-evolution pro creationists will finally have to admit that the world was not actually created 6,000 years ago.


You make a small joke, yes?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.