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CORRECTED: Oldest dinosaur eggs held babies-study

August 2, 2005

(Corrects affiliation of paleontologist in sixth paragraph)

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – Unhatched dinosaur eggs dating back
190 million years carried fully developed embryos that would
have been born clumsy and helpless, scientists said on
Thursday.

Their finding, published in Friday’s issue of the journal
Science, suggests even the earliest dinosaurs tended carefully
to their young. It also raises questions about how the giant
four-legged dinosaurs called sauropods evolved.

“These animals do not have any teeth, and since they are
ready to hatch, that is strange,” said Robert Reisz of the
University of Toronto at Mississauga in Canada, who led the
study.

“The only explanation for that is they must have been fed
by the mother. That would be oldest evidence of parental care
in the fossil record,” Reisz added in a telephone interview.

“We are looking at the very beginning of dinosaur
evolution.”

“It does support the idea that parental care and possible
altricial (helpless) young existed throughout the reign of the
Dinosauria,” paleontologist Jack Horner of Montana State
University agreed in an e-mail.

The eggs come from a dinosaur called Massospondylus, one of
a group called prosauropods that later evolved into the giant
sauropods such as apatosaurus, previously known as
brontosaurus.

“Most dinosaur embryos are from the Cretaceous period (146
to 65 million years ago),” Reisz said in a statement.

The fossil eggs were found in South Africa in 1978, but
scientists have only now been able to open and study them
properly. Reisz’s team used tiny tools to do it.

“We have essentially miniature jackhammers. They are pencil
sized,” he said.

“And we use very delicate dental tools.”

Working under a powerful microscope, Reisz’s team had to
design a vibration-free table to work on.

“When somebody slammed a door in the building, my
technician who preparing this felt that,” Reisz said.

When they got the eggs open, they could see the baby
dinosaurs were just about to hatch. In fact, egg fragments were
all around, suggesting that at least one did.

And the babies did not look like the parents. Adult
prosauropods were slender and two-legged.

The babies looked more like the dinosaurs that developed
later, and they looked like the babies of animals such as birds
and mammals, as opposed to the small but adult-proportioned
young of reptiles.

“The head is quite large. The pelvic girdle is very small.
That’s where most of the muscles that would be used for
locomotion are located,” Reisz said.

“So we are suggesting this was a relatively helpless little
hatchling.”

Very few animals develop as this one appears to have, Reisz
said.

“It starts out as a quadruped and becomes, as it grows up,
as a biped. There are very few examples in nature that do
this,” he said.

One example, however, is a human baby.

“We start out as an awkward quadruped and we manage to
become bipedal,” he said.

Now the researchers can use computers to work out how these
animals grew from a 6-inch (15-cm) long embryo into a 15
foot-(5-meter) long adult.

“This discovery is exciting in providing a major piece of
the puzzle of how sauropodomorphs grew and reproduced,” said
biologist James Clark of George Washington University in
Washington.




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