'Wonderchicken,' 66.7 million-year-old bird fossil, discovered

March 18 (UPI) -- A dinosaur-era fossil of a bird -- nicknamed "Wonderchicken" -- dates back 66.7 million year and is shedding light on early bird evolution, a study published Wednesday said.

The fossil of Asteriornis maastrichtensis, from the Masozoic era, was discovered in a limestone rock formation near the French-Belgian border by a team led by University of Cambridge researchers. It can lead to a better understanding of why birds of that period survived mass extinction while dinosaurs did not, a study in the journal Nature said.

With high-resolution X-ray CT [computed tomography] scans, the researchers were stunned to find a nearly complete bird skull only 1 millimeter beneath the rock's surface. Few bird fossils from the Mesozoic era have been found. The discovery of the "Wonderchicken" fossil indicates that Europe, which had a tropical climate at the time of the dinosaur's demise, was a key area in bird evolution.

"The moment I first saw what was beneath the rock was the most exciting moment of my scientific career," said Dr. Daniel Field of the University of Cambridge, the lead author of the study. "This is one of the best-preserved fossil bird skulls of any age, from anywhere in the world. We almost had to pinch ourselves when we saw it, knowing that it was from such an important time in Earth's history."

The skull is recognizable as that of a bird, and has features common to the group of early chickens and ducks known as Galloanserae.

"Finding the skull blew my mind," said co-author Juan Benito. "Without these cutting-edge scans, we never would have known that we were holding the oldest modern bird skull in the world."