Thursday, December 1, 2011

Gorgeous Dinosaur Nest Found Full of Babies

 A nest full of fossilized dinosaur babies has been discovered in Mongolia, and the find has paleontologists reexamining styles of parental care among the ancient reptiles.

The approximately 75-million-year-old nest shows 15 juvenile members of Protoceratops andrewsi—a relative of Triceratops—entombed in ancient sand dune deposits. The nest was recently discovered by Mongolian paleontologist Pagmin Narmandakh in the region's Djadokhta formation.

The 2.3-foot-wide (0.7-meter-wide) nest is breathtaking, according to David Fastovsky, a co-author on a paper about the dinosaur nest published in the November edition of the Journal of Paleontology.

Unlike other dinosaur nests found with fossil eggs, the babies in this nest appear to have been about a year old when they died.

"We think there's good evidence for some sort of parental care, because these animals are growing together at the nest," said Fastovsky, a paleontologist at the University of Rhode Island. "They did not come fresh out of eggs two minutes ago."

Above, a reconstruction of a previously found Protoceratops andrewsi fossil shows the herbivore's distinctive head frill and beaklike mouth. Protoceratops is a primitive member of Ceratopsia, the dinosaur group that includes Triceratops. Adults could grow to around six feet (two meters) long.

Protoceratops andrewsi lived in a sand sea that existed some 75 million years ago in the center of Asia, where the Gobi is found today.

"Think Lawrence of Arabia—that is the environment that these animals were living in," Fastovsky said. While the landscape was rugged, it must have been biologically productive, as it apparently provided Protoceratops with enough plant life to survive.
 Crowded Nest

The fossil dinosaurs huddle together in the ancient nest.

Scientists once believed that dinosaurs generally followed a crocodile-like model of child care—they would lay their eggs and leave their nests for good. This idea was replaced by the view that dinosaurs raised their young for a time after hatching, the way many birds do.

Now, Fastovsky explained, people understand that the ancient reptiles had parenting styles unlike those of any animals alive today.

Fifteen babies, as seen in the newfound fossil nest, is an unusually large number of offspring for any animal to nurture at once, Fastovsky said. Modern animals tend to have a few young, in which they invest heavily, like humans, or they have a "zillion babies" and show no parental care, like mosquitoes.

"So these [dinosaurs] seem to be something else."
 Sandy Death

As seen above, all of the young Protoceratops in the newfound nest are facing the same direction, giving scientists a clue to how they died.

"Our scenario is that these things were pointed away from the wind as it was blowing during a sand storm, and then they were catastrophically buried by an encroaching dune," Fastovsky said.

"I think in this particular case, it really was dramatic—this fossil really records the last, bug-eyed, terrified minutes of their little lives."
 Beaked Baby

A close-up view shows the head of one of the young Protoceratops with its tiny beaked mouth.

Another fossil discovered in the same region shows an adult Protoceratops and a velociraptor locked in an apparent death grip. "So you have two stunning examples of dinosaur behavior frozen for us to see some 75 million years later," Fastovsky said.

It's likely that velociraptors preyed on Protoceratops young, he added: "The desert environment where they lived just had to be hard, and possibly there were relatively high mortality rates."

Last Looks

A side view shows the jumble of bones in the fossil dinosaur nest. Overall, the newfound nest is "an amazing, beautiful, gorgeous fossil," Fastovsky said.

"I think there's room in the world for really amazing fossils [like this one] to really bring home to people the significance of ancient life on Earth."