Swedish team finds eggs from birdlike dinosaurs

A team of Argentine-Swedish researchers has reported finding fossilized bones and eggs from a giant-clawed birdlike dinosaur in a 70 million-year-old pocket in Patagonia.

• Swedish friction experts unravel curling mystery (14 May 13)
• New drive to address teacher shortage (4 May 13)
• Swedish scientists find new obesity genes (8 Apr 13)

”What makes the discovery unique are the two eggs preserved near articulated bones of its hindlimb,” said Dr. Martin Kundrát at Uppsala University in a statement.

”This is the first time the eggs are found in a close proximity to skeletal remains of an alvarezsaurid dinosaur,” he added.

The eggs of the enigmatic Bonapartenykus ultimus were found in December 2010 in a joint expedition featuring researchers from Sweden’s Uppsala University and Museo Argentino de Ciencias Naturales.

The Bonapartenykus ultimus represents the latest survivor of its kind from Gondwana, the southern landmass in the Mesozoic Era, the researchers said.

With its birdlike skull, tiny teeth, and stunted forearms each sporting an enormous claw, the creature belongs to one of the most mysterious groups of dinosaurs, the Alvarezsauridae. Measuring in at 2.6 metres, it is one of the family’s largest members.

The two eggs found with the bones might have been inside the oviducts of the Bonapartenykus female when the animal perished, the researchers said. But, they added, later eggshell finds suggested that some of the eggs were incubated and contained embryos at a late stage of their development.

On analyzing the eggshell’s microstructure, Kundrát found that it did not belong to any known category. As a result, a new egg-family was designated and named Arraigadoolithidae after Alberto Arraigada, the owner of the site where the eggs were found.

The Uppsala researcher also made another unusual discovery.

”During inspection of the shell samples using the electron scanning microscopy I observed unusual fossilized objects inside of the pneumatic canal of the eggshells. It turned out to be the first evidence of fungal contamination of dinosaur eggs,” he said.

The group’s findings are published in the online edition of the journal Cretaceous Research.