Eggs from a fossil nursery Dinosaurs: From a vast field of sauropod eggs found in Argentina -- some almost perfectly preserved -- come examples on display in Baltimore.

November 19, 1998|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

A photo caption in yesterday's Sun incorrectly identified several baby dinosaur models at the Maryland Science Center as argentinosaurs. In fact, the models should have been identified as young titanosaurs.

The Sun regrets the error.

For the dinosaurs, it was a catastrophe, a sudden river flood that drowned and buried an estimated 100,000 eggs that had been incubating in the warm earth.

But for Argentine paleontologist Rudolfo Coria 70 million or 80 million years later, the flood yielded a scientific bonanza -- a field of fossilized eggs 20 miles in diameter.


Some were so minutely preserved that they held the bones, minuscule teeth and even the skin of the squirrel-sized embryos inside.

"We couldn't believe it," said Coria.

He is director of the Museo Municipal Carmen Funes in Argentina and co-discoverer a year ago of the Patagonian fossil nursery, with Luis Chiappe and Lowell Dingus, of the American Museum of Natural History in New York.

Their report was published in today's issue of the journal Nature and the December issue of National Geographic Magazine.

Coria and his team have so far unearthed more than 100 complete eggs and recovered about 10 that hold fossil embryos.

Those represent the first dinosaur embryos ever found in the Southern Hemisphere and the first ever conclusively identified as those of the long-necked plant-eaters called sauropods.

One of the volleyball-sized eggs -- with no visible embryo -- went on display yesterday at the Maryland Science Center in Baltimore.

Others are being shown in New York and at the Gulf Coast Explorium in Mobile, Ala.

The Science Center's egg will remain here on loan until Feb. 1. The loan came about through Coria's association with Don Lessem's Dinosaur Productions, which has mounted the center's current exhibit, "The Dinosaurs of Jurassic Park."

The displays include other dinosaur eggs from China and France.

"To find the eggs was very nice," Coria said, "but it was really a shock to find the embryos, because always when you find fossil eggs, you hope to find the embryos."

Only rarely do events and chemistry combine to preserve such )) fragile tissues in stone before they decompose. And never before has anyone found fossil traces of the lizard-like embryonic skin.

"It's amazing," said Coria.

His work in a barren and remote corner of northwestern Argentina has produced both the 120-foot, 100-ton argentinosaur the largest terrestrial plant-eater ever, as big as a blue whale -- and giganotosaur, a 40-footer whose discovery three years ago nudged aside Tyrannosaurus rex as the biggest flesh-eater ever.

Johns Hopkins University biologist and anatomist David Weishampel said the gigantic beasts Coria has unearthed in recent years may represent a sort of "arms race" between plant-eaters and carnivores of their day.

Their astonishing bulk threatens the limits of both physics and nomenclature.

Scientists have already used up such superlatives as giganotosaur, titanosaur, seismosaur and supersaur. Future finds, Weishampel said, "may be limited by our ability to name them, because they sure don't seem limited by physics."

Coria suspects the embryos are those of titanosaur, a sauropod that grew to be 45 feet long. Their adult remains have been found before in the region.

But a positive identification must await discovery of some "diagnostic" remains -- pelvic bones or skull fragments inside the eggs.

Dinosaur fossils have turned up in the Argentine desert since the century, Coria said. But until the 1980s, the paleontologists who arrived from South America, Europe and the United States have been interested in other things, like mammals and early reptiles.

Coria, 39, counts himself among the first generation of Argentine dinosaur hunters. Their hunting ground is 55 miles from the nearest city, a dry, nearly barren region much like eastern Montana or the Dakota badlands, where ancient bones are constantly exposed as wind and weather erode the dirt around them.

"It is a remote area, and being that remote they were preserved from predation by fossil thieves," Coria said.

The few ranchers living in the area alert scientists and museums when new bones turn up. But the fossil eggshell fragments went unnoticed.

In November 1997, Coria and Chiappe were in the area looking for primitive birds and the remains of adult meat-eaters when they spotted the egg fragments. As they dug, they turned up more and more of the slightly flattened spheres. Then they began to scrape away at the rock inside.

They found a few tiny bones. And pressed inside one of the shells, "one of the volunteers found a little skin patch," Coria said. "That we dismissed because it was so tiny it could be anything.

"It could be crystallized rock, or weathering, erosion. "

So they kept looking. On the second day, he said, "we found a really nice skin patch. There was no doubt it was skin. It looked like dried lizard skin against the bottom of the egg."

Work at the hilltop site will resume in March. Coria plans to strip away the earth and expose more eggs.

By mapping them, his crew hopes to learn whether the sauropods laid them in individual nests or shared "colonial" nests. Further egg dissections may confirm the embryos as titanosaurs.

Revenues from attendance at the Science Center exhibit -- up 24 percent since the dinosaurs arrived early last month -- yesterday yielded two $3,500 checks to support new dinosaur research.

One went to Weishampel, who will conduct research on the remains of Maryland's state dinosaur, Astrodon johnstoni. The second went to Coria to support his work in Patagonia.

"One in every 10 dinosaurs found in the world in this decade was found within an hour's drive of his museum," said Gregory Andorfer, the science center's executive director.

Pub Date: 11/19/98

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