This is the Wonderchicken , the wonder chicken ( Asteriornis maastrichtensis ), the first modern bird to live 66.7 million years ago, less than a million years before the asteroid impact that doomed all non-avian dinosaurs. However, the winged and beaked descendants of this quail-sized bird survived that mass extinction event, forming a long lineage that includes both chickens and modern ducks.
According to analyzes of fossil remains, which consist of a nearly complete skull and some limb bones, Asteriornis maastrichtensis is closely related to the most recent common ancestor of land and water birds, the researchers report in the journal Nature.
The team, led by the University of Cambridge, believe the new fossil helps clarify why birds survived the mass extinction event at the end of the Cretaceous period and giant dinosaurs did not.
Detailed analysis of the skull shows that it combines many characteristics common to modern chicken and duck-looking birds, suggesting that the affectionately nicknamed Wonder Chicken – which wouldn’t have weighed 500 grams – is close to the last common ancestor of chickens and modern ducks. The fossil was found in a limestone quarry near the Belgian-Dutch border, making it the first modern bird of the dinosaur age to be found in the Northern Hemisphere.
The fossil doesn’t attract much attention, at first, but thanks to high-resolution X-ray CT scans, the researchers saw what was inside that rock: a nearly complete bird skull.
” The moment I first saw what was under the rock was the most exciting moment in my scientific career ,” explained Daniel Field of the Cambridge Department of Earth Sciences and 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 it came from such an important moment in Earth’s history. “
“The discovery of Asteriornis provides some of the first evidence that Europe was a key area in the early evolutionary history of modern birds,” clarifies John Jagt of the Natuurhistorische Maastricht Museum in the Netherlands and a co-author of the study.
Characteristics
The skull, despite belonging to a completely different geological era, has characteristics that are perfectly recognizable in modern birds. The front of the skull is like a chicken, including the nasal bone that was part of the nose, which helped shape its beak. “A free-range chicken will eat whatever you put in front of it,” says Field, and that’s reflected in the shape of the chicken’s unspecialized beak, suggesting that this ancient bird wasn’t picky eaters either. Something that could have a key importance in their survival : “A non-specialized diet is the type of characteristic that could have helped animals like the Chicken Wonder to survive” after the impact of the asteroid.
Another part of the skull is more characteristic of waterfowl like ducks, such as a distinctive bone projecting from the back of the skull to the base of the eye socket and a hooked bone at the back of the jaw.
The rock containing the fossils contains marine sediments, suggesting that the beach was normally inhabited.
Previous estimates, based on molecular analyzes of groups of live birds, suggested that modern birds evolved before the mass extinction event about 66 million years ago, but until now we did not have the evidence . This fossil definitely places a modern ancestor on the scene.
Referencia: Daniel J. Field, Juan Benito, Albert Chen, John W. M. Jagt, Daniel T. Ksepka. Late Cretaceous neornithine from Europe illuminates the origins of crown birds. Nature, 2020; 579 (7799): 397 DOI: 10.1038/s41586-020-2096-0
