'Wonderchicken' From 66 Million Years Ago Is 'Oldest Known Modern Bird,' Scientists Say

Researchers have discovered the remains of an extinct animal that may represent the oldest "modern" bird known to science.

An international team of palaeontologists identified the near-complete fossil skull of the bird, which they have dated to between 66.8 and 66.7 million years ago. This is around one million years before the cataclysmic asteroid impact marking the end of the Cretaceous period that wiped out all large dinosaurs.

Dubbed Asteriornis maastrichtensis, the extinct bird—affectionately nicknamed the "wonderchicken"—shares some features that can be seen in modern-day ducks and chickens, according to a study published in the journal Nature. The palaeontologists say the find sheds new light on the evolution of modern birds, and could help explain why these animals survived the mass-extinction event, while large dinosaurs did not.

"We have discovered the oldest modern bird fossil yet identified," Daniel Field, an author of the study from the University of Cambridge in the U.K., told Newsweek. "Asteriornis maastrichtensis is an early fossil bird close to the origin of the group that today includes chicken-like birds and duck-like birds. Asteriornis lived 66.7 million years ago, at the end of the Age of Dinosaurs, and provides new insights into what modern birds were like early in their evolutionary history."

He continued: "In addition to providing our best glimpse yet at the skull of an early modern bird from the Age of Dinosaurs, the fossil can help us understand which features may have helped modern birds survive the extinction event that wiped out the giant dinosaurs. We believe that several features exhibited by Asteriornis, such as a relatively small body size, ground-dwelling habits, an ability to fly, and a generalized diet were key attributes that would have favoured the survival of modern birds in the aftermath of the asteroid impact."

According to the researchers, the latest findings indicate modern birds emerged shortly before the devastating impact. To date, the early evolution of the so-called "crown" group of birds—which includes all living birds, plus all the descendants of their most recent common ancestor—has been shrouded in mystery, due to a significant lack of fossil evidence within the Mesozoic era (around 250–66 million years ago.)

But the discovery of A. maastrichtensis goes some way to fill this gap in our knowledge.

"We have known for a while that the earliest stages of modern bird evolutionary history took place towards the end of the Age of Dinosaurs, but we haven't had much direct evidence of modern birds from the fossil record of that time," Field said. "Asteriornis provides the clearest evidence yet of what kind of modern birds were actually around near the end of the Age of Dinosaurs, and it seems like only the very earliest branches of the modern bird family tree had arisen by the time the end-Cretaceous asteroid struck."

The fossil skull was found in a limestone quarry near the border between Belgium and the Netherlands in northern Europe, hidden within a seemingly nondescript piece of rock. The location of the find is also significant in and of itself the researchers say.

"This is the first time a fossil of a modern bird from the Age of Dinosaurs has ever been found from the northern hemisphere," Field said. "The fact that the fossil was found in Europe is incredibly exciting, because it suggests that future discoveries of even older modern birds might come from Europe. Until now we were not certain that modern birds were even present in Europe during the Age of Dinosaurs."

Initially, the researchers could only see few small fragments of leg bone sticking out of the piece of rock. However, this piqued their interest enough to conduct high-resolution CT scans of the specimen in a laboratory at the University of Cambridge, which revealed the hidden skull. According to Field, seeing the scans for the first time was the "most exciting moment" of his scientific career.

"The actual fossil specimens don't look very beautiful or interesting at first—they're basically just a few small rocks with some broken limb bones poking out," he said. "However, when we CT scanned those blocks in order to peer beneath the surface of the rock, we were absolutely shocked to discover a nearly complete, three-dimensionally preserved fossil skull within one of the tiny blocks. This is the earliest modern bird skull ever seen, and is the first time a modern bird skull has been found from the Age of Dinosaurs."

Even though the skull is tens of millions of years old, it is still clearly recognizable as a modern bird, resembling a mixture between a chicken and a duck, according to the researchers. The researchers think the extinct bird weighed under 15 ounces, and was relatively small in size, with fairly long legs. Given the bones were found in marine sediments, they suggest the wonderchicken may have spent its life by the shore at a time when the coastal environment of this part of northern Europe may have resembled those of today's tropical islands.

Asteriornis maastrichtensis
Artist’s reconstruction of the world’s oldest modern bird, Asteriornis maastrichtensis. Phillip Krzeminski

Asteriornis takes its name from Asteria, a Titan goddess of falling stars in Greek mythology who transformed herself into a quail.

"We thought it was an appropriate name for a creature that lived just before the end-Cretaceous asteroid impact," Daniel Ksepka, a co-author of the study from the Bruce Museum in Greenwich, Connecticut, said in a statement. "We believe Asteriornis was close to the common ancestor that today includes quails, as well as chickens and ducks."

Kevin Padian, a researcher in the Department of Integrative Biology and the Museum of Paleontology at the University of California, Berkeley, who was not involved in the latest study, said the paper was "important" because it describes the best-preserved specimens of a bird that is extinct, and yet is the earliest known member of the living group of birds.

"This bird belongs to the group that you could informally call poultry," he told Newsweek. "That is to say, chickens and ducks and geese and quail and so on. The fact that you have a member of that group present just a short time before the end of the Cretaceous means that other groups of birds had also evolved by that time, even if we don't find their remains."

"For example, the poultry group is closely related to the other living groups of birds like crows, woodpeckers, warblers, and the like. Those actual birds were not present in the latest Cretaceous, but their ancestors were. Just like this new bird is an ancient member of the poultry, but not exactly like any living member."

The study also implies that the group of birds that includes the ostrich, the rhea, the emu, and the kiwi were also present by this time period, and that they must have evolved in a very short burst of time. This is because scientists have not found any bones that clearly belong to these groups of birds earlier in the fossil record.

"So, this new bird is long extinct, but still clearly belongs to the groups of living birds. It's the oldest known well-preserved fossil in that group. Others have been reported in the past, but they had either been questionable or the authors were not able to recover it as among the groups of living birds in their study," Padian said.