December 21, 1995 in Nation/World

What Came First, The Dinosaur Or The Egg? Fossil Find Links Dinosaurs To Birds

Peter Gorner Chicago Tribune
 

A prehistoric bone yard entombed for eons by the rocky red sands of Mongolia’s Gobi Desert has yielded one of the great finds in paleontology: a nesting dinosaur fossilized in the act of incubating its eggs.

The discovery, announced Wednesday, of the ostrich-sized, tailed dinosaur - a rare and bizarre toothless predator known as an oviraptor - provides the first direct evidence of parental care-giving among dinosaurs. It also provides the most graphic evidence so far of their remarkably birdlike habits.

“Birds are a kind of dinosaur,” said Mark A. Norell of New York’s American Museum of Natural History, who found the new fossil. “By its skeleton, the oviraptor is much more closely related to later birds than it is to other meat-eating dinosaurs.

“That’s why we would expect to find birdlike behavioral characteristics in dinosaurs like oviraptors. They shared a common ancestor with birds.”

The specimen was unearthed at a spectacular fossil trove called Ukhaa Tolgod in south-central Mongolia.

Apparently trapped by a sudden sandstorm about 80 million years ago and preserved in a sort of freeze-frame, the 400-pound oviraptor is crouched atop a nest of at least 15 eggs with its hind limbs parallel and folded, one on each side of the nest.

The posture is identical to the brooding position of chickens and pigeons. The arms are turned back, encircling the nest protectively.

Arranged in a circle, the cigar-shaped eggs, about 7 inches long and 3 inches wide, correspond to the contours of the parent’s body with the broad ends facing the nest’s center. Many birds arrange their eggs the same way.

Norell can’t say whether the parent dino was male or female, or if it was warming the eggs or protecting them from the dry desert heat; Gobi temperatures may swing 200 degrees between summer and winter, with roaring sandstorms each spring that make Beijing, China, often turn orange from Gobi dust.

Most modern birds incubate their eggs to maintain a constant temperature. That may have been the original purpose of nesting, Norell said, or it could have arisen as a modification of some earlier unknown behavior.

But the new fossil adds to the scientific consensus that the birds known today - at least 10,000 different species - are really feathered dinosaurs.

Norell seeks to illuminate the relationship between the two. His ambition, in fact, is to find a complete fossil of the earliest modern bird.


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