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More on the Massospondylus embryos



Oldest dinosaur eggs yet held hapless babies-study By
Maggie Fox, Health and Science Correspondent
1 hour, 6 minutes ago

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 the University of Montana 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 quadriped 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 quadriped 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.