Chinese fossil of a Jurassic bird rewrites history of avian evolution

The fossil of a Jurassic bird unearthed in southeastern China has major implications for the history of avian evolution, researchers say.

The newly discovered Baminornis zhenghensis, a quail-sized bird, roamed the skies some 150 million years ago during the Jurassic period, according to a study published Wednesday in the journal Nature, meaning it is among the oldest birds known to mankind, along with the iconic Archaeopteryx that was discovered in Germany in 1862 and is of similar age.

“For more than 150 years now, Archaeopteryx has stood alone,” said Steve Brusatte, a University of Edinburgh paleontologist who wrote a commentary accompanying the study.

“During all of that time, it has remained as the only unquestionable bird fossil from the Jurassic Period,” he told NBC News in an email.

While there have been other birdlike Jurassic fossils found here and there, Brusatte said, there was a “huge mystery and a frustrating gap” in the fossil record: If Archaeopteryx was flying by then, other birds must have been too. So where were their fossils?

The 2023 discovery of Baminornis in Zhenghe county in China’s Fujian province, now among the most important discoveries since Archaeopteryx, helps fill that gap, he said, making it the “second unquestioned bird from the Jurassic Period.”

Min Wang, the lead author of the study, said it was a “very exciting” discovery.

“These two fossil birds have systematically changed our understanding about the earliest evolution of birds,” the paleontologist from the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences told NBC News in an email.

“They demonstrate that the origin of birds is much earlier than current thought.”

Unlike the half-bird, half-reptile Archaeopteryx, which had a long and skinny tail similar to that of a velociraptor, Baminornis had a short tail with some of its vertebrae fused into a short, stubby nubbin called a pygostyle — a crucial aerodynamic feature that pushes the body’s center of mass toward the wings, similar to those in modern-day birds that help them fly better.

Until the discovery of Baminornis, short tails had been found only in birds known to have lived around 20 million years later, such as Eoconfuciusornis and Protopteryx.

“What excites me most is that it is a more advanced bird than Archaeopteryx, and it could fly much better,” Brusatte said.

Baminornis was much more anatomically complex than Archaeopteryx, which Brusatte said was a “primitive” bird with claws and sharp teeth like its dinosaur ancestors.

Archaeopteryx, which played a crucial role in determining that today’s birds evolved from dinosaurs, was a “textbook example of a creature caught in the act of evolution like a freeze frame,” he added.

The vast difference between the two similarly aged birds, discovered about 5,500 miles apart, has led the team behind the Nature study to believe that avian evolution occurred millions of years earlier than previously thought, with the estimate now at about 164 to 172 million years ago.

In addition to dozens of fossils of aquatic or semiaquatic animals, the Zhenghe Fauna collection, as it’s referred to, includes at least three fossils so far that belong to the group including birds and their closest relatives. The researchers said this suggests the collection holds great potential to “enrich our understanding of early bird diversification” and “fill a critical gap in the evolutionary history of terrestrial ecosystem” toward the end of the Jurassic period.

Though the Baminornis fossil preserved much of the skeleton, the feathers were not preserved, leaving unanswered questions about the size and structure of its wings. It was also missing the skull, limiting clues about the bird’s diet.

Nevertheless, “Baminornis tells us that a variety of birds lived during the Jurassic, and they flew in different ways,” Brusatte said.