Found: Dinosaur With A Heart
North Carolina researchers say the discovery of a 66 million-year-old dinosaur skeleton may change the way scientists think about the largest creatures to ever roam the earth.
CBS News Correspondent Cathy Moss reports the remains of the small dinosaur were found six years ago, complete with a fossilized heart. That's a first.
The heart has two ventricles and a single aortic stem the researchers say resembles the heart of a mammal or bird more than that of a reptile. This leads to the conclusion that some, if not all dinosaurs, were warm-blooded, not cold-blooded as had been commonly believed.
"This was a major wakeup call," said paleontologist Dale Russell, senior research curator at the North Carolina Museum of Natural Sciences, where the skeleton is on permanent display. "The world has never seen this before."
Cold-blooded reptiles usually have a single ventricle, but even in those with four chambers, such as a crocodile, the blood is pumped through a double aorta.
Warm-blooded dinosaurs would have had higher metabolisms than cold-blooded creatures and thus would have eaten more, ranged farther, lived in colder climates, and moved faster and for longer periods of time. They would have been capable of the swift and sustained motion typical of modern birds and mammals.
The researchers, led by Russell and Paul E. Fisher, director of the Biomedical Imaging Resource Facility at N.C. State University, said the discovery could lead to new ways of thinking about the behavior and ecological impact of dinosaurs.
At the very least, they think, it will intensify scientific debates over whether dinosaurs were warm-blooded and whether birds, which also have four-chambered hearts, evolved from dinosaurs.
The findings appear in Friday's issue of the journal Science.
A modern medical X-ray of the dinosaur fossil found clear evidence that the animal had four heart chambers that sent blood directly to and from the lungs and then pumped the oxygen-rich blood to the body through a single arched aorta, similar to how the human heart works.
The dinosaur fossil was found on a South Dakota ranch in 1993 by Michael Hammer, who co-authored the study. He dubbed it "Willo" after the wife of the owner. Hammer recovered Willo without disturbing the dark mass he found in the chest cavity.
Researchers initially suspected that the mass could be fossilized soft tissue, but such tissue usually decays before it can become fossilized.
Russell said the fossil was apparently buried in waterlogged sand and that the soft tissue changed into a soap-like substance that petrified rather than decayed— a process called saponification.
The bottom line, according to Russell: "We got lucky".
The fossil is that of a Thescelosaurus, or "marvelous lizard," an ornithischian, or "bird-hipped" plant eater that lived in the late Cretaceous period, about one million years before the dinosaur era ended 65 million yearago.
Size-wise, Willo is rather small as far as dinosaurs go. Russell estimates it was about the size of a small pony and weighed about 660 pounds, and that it was able to move very rapidly using its massive rear legs.
The North Carolina Museum paid more than $300,000 to have Willo studied and displayed with part of the skull, spine, ribs and tail still embedded as they were found.