Revealing the secrets of life inside a dinosaur egg

Rare fossilised embryos found at the largest dinosaur nesting site on Earth have enabled scientists and CGI specialists to recreate a vision of life inside a dinosaur egg

The record breaking nest site, named Auca Mahuevo, is found in the Neuquén Province of Argentina and was discovered accidentally in 1997 by a team under the direction of Dr Luis Chiappe of the Dinosaur Institute at the Natural History Museum of Los Angeles County.

According to Chiappe, ‘serendipity’ is palaeontology’s middle name, as he was just a few days into an expedition searching for something quite different, when the team stumbled across this prehistoric treasure trove.

Speaking to BBC Earth, he recalled the moment he realised the significance of a discovery which would change the course of his research for the next five years.

“It is a very emotional feeling to find something so important, something no one else has ever seeing before. I remember how one team member, who was walking way ahead of me, came back to show me some chunks of "rhea eggs". I immediately recognised that the fossils were not those of a rhea (an ostrich-like bird that lives in Patagonia) but those of dinosaurs.”

These remarkable findings have enabled scientists and CGI specialists to recreate a vision of life inside a dinosaur egg, as part of a new BBC/PBS coproduction documentary Attenborough and the Giant Dinosaur.

The long-necked sauropod dinosaurs that laid these eggs belonged to titanosaurs, a group containing the largest dinosaurs, with specimens believed to reach lengths of up to 37 metres and weighing between 80 and 100 tonnes.

The discovery became even more significant when the scientists realized that an incredibly high proportion of these eggs contained the fossilized remains of baby dinosaurs. These are the first known embryonic remains of any sauropod dinosaurs to be discovered, with the eggs proving to be astonishing time capsules.

Preserving the skulls and bones, the mineralised remains proved so intact that the pattern of their scales embedded within the skin of the dinosaur foetuses could be clearly seen.

These nests in which embryos were found also offer tantalising glimpses of prehistoric life. The sheer number and distribution of eggs found together suggest that hundreds of female titanosaurs may well have gathered at this nesting site between 79 and 83 million years ago.

They are believed to have laid their eggs in clutches of up to 30 or 40 at a time, in shallow depressions. The remains of vegetation have even been found in some nests, suggesting the dinosaurs may have used the heat from decomposing leaves to aid in the incubation.

Scientists have also deduced from this astonishing find that the eggs were laid on an old river plain. When the river suddenly flooded, the deposited mud then effectively safely entombed the eggs for millions of years until their fortuitous discovery.

"The Auca Mahuevo nesting site is truly spectacular, but imagining hundreds of those behemoths gathering for the purpose of nesting is even more so,” says Chiappe.

'Attenborough and the Giant Dinosaur' will be shown in the UK on Sunday 24 January at 18:30 GMT on BBC One.

'Raising the Dinosaur Giant' will be shown in the US on Wednesday 17 February on PBS at 20:00 ET.

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