Beaked dinosaur sheds new light on evolution of birds

The discovery of a strange-looking dinosaur with a beak-like snout, feathers and wing-like limbs has forced scientists to rethink the relationship between dinosaurs and birds.

Palaeontologists found the fossilised bones of the 90 million-year-old creature in a block of sandstone in Argentina. The dinosaur, called Buiteraptor, belongs to a group of carnivorous theropods called dromaeosaurs that ran on two legs and are thought to be distantly related to modern-day birds.

It is the first time a specimen from the group has been found in the southern hemisphere, which shows dinosaurs were more widely dispersed around the world than previously imagined.

Peter Makovicky, curator of dinosaurs at The Field Museum in Chicago, who led the excavation in Patagonia, said until now dromaeosaurs had been found only in Asia and North America, which once formed the landmass of the northern hemisphere.

Such distribution suggested those dinosaurs originated on the ancient continent - called Laurasia - and did not manage to migrate to the other ancient continent of Gondwana in the south before they began to drift apart.

"Buiteraptor... tells a bigger story about the Earth's history," Dr Makovicky said. "It... provides definitive evidence for a more global distribution ... for dromaeosaurs than was previously known, [and] suggests dromaeosaurs on northern and southern continents took different evolutionary routes after the land masses they occupied drifted apart."