Dinosaur Fossils and the Flood

An artist's rendering shows what the embryos from Auca Mahuevo in Argentina may have looked like as they grew, with scaly skin, unusual nasal openings at the top of their heads and a thin eggshell with airholes like chicken eggs.

Eggs contain traces of skin and bone from
unhatched sauropods, researchers say

Fossilized dinosaur
embryos found

By Alan Boyle
MSNBC

Nov. 17— A prehistoric nesting ground in Argentina has yielded a treasure trove of fossilized dinosaur embryos, complete with traces of skin, scientists say. They say the discovery has produced “the first unequivocal embryonic remains” from a class of plant-eating dinosaurs known as sauropods. But don’t expect a real-life sequel to “Jurassic Park.”

These are just a few of the thousands of fossilized dinosaur eggs found at a nesting site in Argentina during an expedition sponsored by the American Museum of Natural History and the Museo Municipal Carmen Funes.

THE NESTING site at Auca Mahuevo in Argentina’s Patagonia region contains thousands of dinosaur eggs, researchers said. More than a dozen eggs and nearly 40 egg fragments were recovered last year during an expedition sponsored by the American Museum of Natural History and the Museo Municipal Carmen Funes. The researchers speculated that some catastrophe, perhaps a huge flood, prevented the 6-inch-diameter eggs from hatching.

The specimens, which are at least 71 million years old and perhaps as old as 89 million years, were remarkable: Not only were there embryonic bones within the fossilized shells, but there were also traces of skin casts, reflecting tiny patterns on the scales of the unhatched dinosaurs. One of the specimens appeared to have a stripe of scales that probably ran down the creature’s back, the researchers reported in Thursday’s issue of Nature. Paleontologists said the skin patterns — as well as the pencil-like teeth and the structure of the skulls — clearly indicated that the embryos were sauropods, a class of large-bodied, small-brained, four-legged herbivores that includes Diplodocus and apatosaurs (formerly known as Brontosaurus).

Fossilized skin from a dinosaur embryo reveals a scaly pattern. The speciment was discovered in Argentina during an expedition sponsored by the American Museum of Natural History and the Museo Municipal Carmen Funes.

“The anatomical information of the bones and teeth allow a confident identification of the Auca Mahuevo embryos as sauropod dinosaurs,” the researchers wrote. They said the findings contradicted previous speculation that sauropods might have given birth to live young rather than laying eggs. Heading the research team were Luis Chiappe and Lowell Dingus, paleontologists at the American Museum of Natural History, and Rodolfo Coria of the Museo Municipal Carmen Funes. Another member of the team, Frankie Jackson of the Museum of the Rockies, said the key contribution of the new research was to link the eggs conclusively to a particular type of dinosaur.
“The preservation on these is pretty amazing, and hopefully there will be other results from the study of these eggs,” she said. Other authors of the Nature study were Anusuya Chinsamy of the University of Cape Town and Marilyn Fox of the Peabody Museum of Natural History. The idea of finding dinosaur embryos, complete with the pattern of their skin, might lead some to imagine a scenario paralleling the plot of “Jurassic Park,” in which dinosaurs were re-created by manipulating DNA recovered from ancient specimens. However, fossils like the dinosaur eggs are composed of minerals that have taken on the form of bones and other tissue, rather than the organic material itself. The preserved “skin,” for example, is actually a cast of the embryos’ original skin, containing clay, quartz and a carbonate mineral.

New York, Nov. 17 - Scientists have found a vast dinosaur nesting site in Argentina that includes thousands of fossil eggs. Inside egg fragments, they found the first embryo remains from a major class of large dinosaurs and the first fossils of embryo skin from any dinosaur.

Discoveries from the site should shed light on the early development of sauropods, a class of plant-eaters with long necks and tails, small heads and four elephant-like legs. The sauropod family included the largest animals ever to walk the Earth.
    The badlands site, which covers one square mile, is littered with dark-gray fossil fragments of round, rough-textured, six-inch eggs. “You see eggshells everywhere,” said Luis Chiappe of the American Museum of Natural History in New York. The eggs were laid 70 million to 90 million years ago, apparently by titanosaurs that stretched about 45 feet long. The hatchlings might have been only about 15 inches long.
    From the embryonic remains, “We’re really getting a look at what these animals would have looked like to us, and felt like to touch, when they hatched,” said Lowell Dingus of the Museum of Natural History. Chiappe, Dingus and others describe the finds in the next issue of the journal Nature, which will be released Thursday.
    Scientists found so many embryonic remains that it appears catastrophe struck the nesting ground, keeping many eggs from hatching, Chiappe said. Floods may have penetrated the porous shells and drowned the embryos, he said. The flooding also could have carried in layers of silt that kept the eggs so well preserved.   The modern-day result is embryonic bones, which look like tiny light brown flakes surrounded by green mudstone in eggshell fragments and dark patches of fossilized skin within the shells.
    The haul includes approximately 70 shell fragments containing pieces of fossilized skin in fingernail-size patches, with scales clearly visible. No complete embryo skeletons were found, but even finding the collapsed bones is a rarity. Before the new find, embryonic remains had been identified from only five species of dinosaur.
    “If you’re a dinosaur paleontologist, then I think it’s a pretty exciting and wonderful discovery,” said Kenneth Carpenter of the Denver Museum of Natural History, who is familiar with the work.   For one thing, the find knocks down a controversial suggestion that sauropods gave birth to live young, Carpenter said. That idea had arisen because sauropod fossils are common in some older rocks in North America, yet no remains of eggs ever had been found.
    And the sheer number of eggs at the site suggests dinosaurs converged repeatedly in one place to lay them, Carpenter said. While scientists have speculated about such behavior, “We’ve never had any real good evidence that’s what dinosaurs would do,” he said.
    The discovery also shows that a particular kind of large, round dinosaur egg found in Africa, India, China, Europe and South America is often from sauropods, Chiappe said.   Carpenter said that had been proposed before because the eggs were so big, but that the new discovery finally solves the mystery after about 100 years of debate.
    The site was discovered a year ago in Neuquen, a province in northwestern Patagonia.