Dinosaur Embryos Found (3 articles)

[Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>]

Dinosaur Egg Suggests Fierce Animal May Have Been Tender Parent
11/03/94

By PAUL RECER
AP Science Writer

WASHINGTON (AP) - An 80-million-year-old egg from a Mongolian desert contains
the first embryo ever found of a meat-eating dinosaur and suggests the fierce
beast known as "egg thief" may have been a tenderly caring parent.

Mark A. Norell of the American Museum of Natural History said the embryo
discovery changes scientific conclusions about an entire species of dinosaurs.

A fossil of the dinosaur species was first found at an ancient Gobi Desert
nest in 1923. Researchers concluded that the animal died while eating eggs of
some other animal and named the dinosaur oviraptor, Latin for "egg seizer" or
"egg thief."

But with the discovery of the embryo, said Norell, there is evidence that the
1923 find was misinterpreted and oviraptor was given a bum rap.

"We have shown that the animal actually was protecting or brooding those eggs"
and not eating them, Norell said, and that the eggs were the oviraptor's own.

A report on the dinosaur study appears Friday in the journal Science.

Jacques Gauthier of the California Academy of Science said Norell's research "is
a stunning find."

"It confirms a lot of ideas" about how some dinosaurs may have cared for their
eggs and protected their nests, said Gauthier. And it also suggests experts
should be more careful about leaping to conclusions, he said.

Norell and his team found the dinosaur nest at a Gobi Desert site called Ukhaa
Tolgod in Mongolia. He said there were a number of other nests nearby,
suggesting the area was a major nesting site some 70 to 80 million years ago.

The nests, he said, contained eggs of the type identified in the 1923 study as
those of a plant-eating dinosaur called protoceratops.

But in one of the nests, Norell said his team found an egg that contained a
perfectly preserved fossil of what was unmistakably an oviraptor.

"Now we can look back and say that those protoceratops eggs are actually
oviraptor eggs," he said.

Norell said the same nesting area contains 20 fossils from adult oviraptors and
strongly supports the suggestion that the animals protected and cared for their
eggs.

At the nests, he said, clutches of six-inch-long eggs were consistently arranged
in a circular pattern with the large, blunt end of the eggs always pointing
outward.

"That is in a brooding position," said Norell. "It proves that they manipulated
their eggs in the way that a bird might. So the evidence is strong that the
animal could have been brooding."

Oviraptor was flightless, but it resembled some birds. It was up to eight feet
tall, ran on powerful hind legs and had two long front limbs armed with curving
claws. It had a long, S-shaped neck, a skull with large eyes and a powerful beak
and, for some of the animals, a distinctive bony crest on top.

The animals were undoubtedly meat-eaters, probably pulling their food apart with
their beaks, as do eagles and hawks.

Even though oviraptor may have gotten its name by mistake 70 years ago, Norell
said the animal may indeed have raided the nests of other species.

In one of the oviraptor nests, researchers found the tiny skulls from baby
dromaeosaurs, another type of dinosaur. Norell said the skulls could have been
from animals attacking the oviraptor nest, or the embryos from eggs laid in the
nest by another dinosaur species. But, more likely, they could have been the
remains of an oviraptor meal, he said.

"The oviraptor parents could have gone out and cleaned out somebody's nest and
these were just the left-over pieces," he said.

The co-authors of the study with Norell included five researchers from the New
York museum and three scientists from Mongolia.

Science, which published the work, is the journal of the American Association
for the Advancement of Science.

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In the same nest the scientists uncovered two tiny skulls of another type of
carnivorous dinosaurs from the group known as dromaeosaurs, possibly
Velociraptor.

The skulls may have been those of embryos or newborns. But to find these skulls
in the same nest with an embryo of another species is extraordinary,
paleontologists said.

The little dromaeosaurids were most likely brought to the nest as food by the
adult oviraptorids. Or else they may have been predators, raiding the nest, or
nest parasites, as cuckoos are today. Adult cuckoos lay their eggs in the nests
of birds of other species, abandoning them to be hatched and raised by the
surrogate parents.

Dr. John H. Ostrom, a paleontologist who recently retired from the Yale
University faculty, said the findings bolstered the case for a dinosaur-bird
ancestral link.

This is the first strong evidence for birdlike nesting behavior by theropods,
the group of dinosaurs from which birds perhaps evolved more than 150 million
years ago. Of course, these oviraptorids, having lived much later, would not
have been among the direct ancestors of birds.

The other authors of the journal report of the embryo discovery, besides Dr.
Norell and Dr. Novacek, were Dr. Luis M. Chiappe, Amy R. Davidson and Dr.
Malcolm C. McKenna of the American Museum; Dr. James M. Clark of George
Washington University; Dr. Dashzeveg Demberelyin and Dr. Barsbold Rhinchen of
the Mongolian academy, and Dr. Perle Altangerel of the Mongolian Museum of
Natural History.


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FOSSILIZED EMBRYO OFFERS NEW INSIGHT ON DINOSAUR INFANCY
11/3/94
By JOHN NOBLE WILFORD

In a discovery that should begin to round out knowledge of the full life cycle
of dinosaurs, paleontologists exploring the Gobi Desert of Mongolia have found
the first fossilized embryo of a meat-eating dinosaur. Only six or seven other
dinosaur embryos are known to science, and none is as exquisitely preserved as
this one.

Curled up and resting in part of its oblong egg, the specimen looks very much
like a tiny dinosaur on the half-shell. With tail and all, the fully extended
embryo would probably measure eight inches long. But it is still in the fetal
position, the head tucked near the knees. A hand is over the face.

Except for the missing pieces of the tail and the top of the skull, everything
about the skeleton seems complete, with individual vertebrae, pelvic bones and
limbs all well formed and clearly identifiable.

In his laboratory this week, Dr. Mark A. Norell, associate curator of vertebrate
paleontology at the American Museum of Natural History in New York, who made the
discovery, tenderly cupped the 75-million-year-old specimen in his hand.

It was strange to see a hunter of those ancient reptiles, best known for their
fierce teeth, sharp claws and gargantuan bones, smiling over a find so delicate
and vulnerable.

"I knew this was an embryo as soon as I saw it lying on the ground," Norell
said. "I knew from the ankle bones it was a theropod," the broad group of
dinosaurs that includes such agile carnivores as Tyrannosaurus rex,
Velociraptors and the smaller, birdlike Oviraptors.

An analysis in the laboratory, after the sand and minerals were painstakingly
cleaned away, confirmed Norell's first impressions. It also determined that the
tiny bones had already ossified, indicating that the embryo had been close to
hatching.

The cranial features, Norell said, identified it as a member of the oviraptorid
family, or dinosaurs that grew to be more than six feet long with a short head,
an elongated neck, toothless jaws and a hornlike bump on the end of its snout.

They probably looked something like an ostrich with a tail, running about on two
legs and attacking prey with strong claws on their forelimbs.

Details of these findings are being reported Friday in the journal Science by
Norell and a team of American and Mongolian scientists. The discovery was made
in the western Gobi in the summer of 1993 on an expedition from the American
museum and the Mongolian Academy of Sciences, led by Dr. Michael J. Novacek, a
paleontologist and dean of science at the museum.

Other scientists examined the specimen last week at a meeting of the Society of
Vertebrate Paleontology in Seattle and agreed that it was an important discovery
that should open a window on the early life of dinosaurs and their nesting
behavior.

It could also provide further support for an ancestral connection between
dinosaurs and birds, as many scientists have theorized.

"This is absolutely noncontroversial," Norell said in an interview. "Everyone
agrees it's an oviraptorid."

John R. Horner, a dinosaur paleontologist at the Museum of the Rockies in
Bozeman, Mont., praised the discovery because good dinosaur embryos are so rare.
"Mostly we have adults to work with," he said, "and that only tells you about
adults."

In particular, Horner said, the bone development of embryos could provide
evidence of whether, as hatchlings, these dinosaurs were able to walk or had to
stay in the nest for some time.

An examination of the few embryos of plant-eating dinosaurs, he said, had
produced conflicting results, indicating some probably could walk immediately,
but others could not.

Since most dinosaur eggs are rock-solid fossils, any embryos preserved inside
can only be studied indirectly, and not too well, with X-rays and CAT scanners.

In his excavations in Montana, Horner has made many important discoveries about
the parental practices of plant-eating dinosaurs, finding eggs, shells and
juvenile skeletons in large nests arranged not unlike those in a teeming penguin
colony.

The remains of an adult associated with some nests suggested that parental
nurturing might be part of the behavior of some dinosaur species. One of these
was a duck-billed species given the name Maiasaura, the good mother reptile.

The oviraptorid embryo was found at Ukhaa Tolgod, a mile-wide basin in the
western Gobi that has proved to be one of the richest lodes of vertebrate
fossils from the end of the age of dinosaurs.

The American-Mongolian expedition discovered the site in 1993 and returned this
past summer for further exploration.

Erosion had exposed a clutch of fossil eggs, which were about five inches long
and two and a half inches wide. One was so badly weathered that the top had worn
away, revealing the tiny embryo skeleton. Besides giving scientists a rare view
of early dinosaur life, the discovery immediately confronted them with a mystery
of mistaken identity.

In 1923, an American Museum expedition led by Roy Chapman Andrews discovered the
first known cluster of dinosaur eggs at a spectacular site in the Gobi called
Flaming Cliffs. The eggs were assumed to belong to a species of plant-eating
dinosaur, known as Protoceratops, because it was the most common dinosaur 
fossil the explorers had found in the Gobi.

They read even more into this prehistoric scene. Lying atop the nest was the
strange-looking skeleton of a previously unknown dinosaur. It was identified as
a carnivore that probably died in a sandstorm while sucking the Protoceratops
eggs. So the fossil was named Oviraptor, which means "egg seizers" in Latin,
and ever since its reputation has suffered accordingly.

Norell's discovery in the basin 200 miles from the Flaming Cliffs has revealed
that the dinosaur had been misnamed. Determining that these were the eggs of the
supposed predator itself, not a Protoceratops, amounted to a vindication for
Oviraptor. "Rather than eating the eggs, they were incubating them or protecting
them," Norell said.