Nesting dinosaur discovered in Mongolia.
"The position of this animal is really definitive. It looks just like a giant chicken with big claws on its feet sitting on a nest," says Mark A. Norell of the American Museum of Natural History in New York City.
The 8-foot-long ostrichlike dinosaur belongs to the genus Oviraptor and apparently died suddenly some 80 million years ago, when a large dust storm entombed it.
Norell unearthed the fossil during an expedition conducted by the museum and the Mongolian Academy of Sciences. The researchers reported their find in the Dec. 21/28, 1995 Nature.
Although scientists have long suspected that some dinosaurs tended their nests and cared for their young, this is the strongest evidence yet that any dinosaur actually sat on its nest much as modern birds do. The Oviraptor fossil has its legs folded beneath its body, and its forelimbs surround a clutch of at least 15 eggs arranged in a circle.
"It's a wonderful find," comments Kevin Padian of the University of California, Berkeley. "It is probably the most spectacular discovery in terms of behavior since the fighting dinosaurs were discovered in the 1970s," he says, referring to another Gobi find-the fossil of a predatory Velociraptor with its front claws locked around the skull of a Protoceratops skeleton.
Finding a dinosaur in a brooding position bolsters the widely held idea that birds descended from so-called theropod dinosaurs such as Oviraptor, say proponents of the theory.
"It fosters the very close link between dinosaurs like Oviraptor and Velociraptor and birds," says Norell. He suggests that brooding behavior evolved first in dinosaurs and was inherited by their avian descendants.
Dissenters from this theory brush aside such an interpretation, pointing out that pythons also sit on their eggs.
The Gobi fossil also heats up a long-simmering debate over dinosaur physiology: Were these ancient reptiles warm-blooded or cold-blooded? If Oviraptor sat on its eggs to keep them warm, the action would suggest that dinosaurs were warm-blooded, like modern birds.
While Norell finds the new specimen "suggestive of incubation," he does not rule out other possible explanations for the brooding behavior. The dinosaur may have sat on its nest to protect it from predators or to shield it from the sun or dust storms.
In any case, the discovery of a doting Oviraptor parent further vindicates this dinosaur, whose name means "egg stealer." The label stems from a misinterpretation on the part of American Museum scientists when they first visited the Gobi in 1923. The researchers found the fossil of an unknown animal with eggs presumed to belong to Protoceratops, so they reasoned that the new species had died while plundering the nest.
Norell cleared up the misconception last year. He discovered an Oviraptor embryo inside the same type of egg, suggesting that the original specimen had been tending its own nest. The new discovery of an Oviraptor in a brooding position demonstrates explicitly how this dinosaur cared for its eggs.
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|Title Annotation:||Science News of the Week; fossil Oviraptor found in Gobi Desert indicates that dinosaurs may brooded like modern birds|
|Article Type:||Brief Article|
|Date:||Jan 6, 1996|
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