China's Jurassic Phoenix: New Fossil Suggests One of the Earliest Birds May Never Have Taken to the Sky

I have a bird feeder in my garden. We got it to entertain our cat (he is the worst hunter ever and has only ever successfully caught a) an already dead bird, and b) a fledgling that fell from its nest). We like to say we are renewing his 'Cat TV' subscription when we refill the bird feeder.

Initially, very few birds came to visit; over time, more and more have come to entertain our cat, from giant red-eyed pigeons that just spill everything to tiny bronze mannikins (Spermestes cucullata).

Every once in a while, I'm reminded that the distant ancestors of these birds were dinosaurs. When we think of early birds, we think of things like Archaeopteryx, Anchiornis, and other ancient fossil animals that shared the earth with other dinosaurs. We think of them patrolling the skies, as Allosaurus stalked the lands, Stegosaurus lumbered along in herds, and plesiosaurs swam through the depths.

Now scientists in China have discovered a fossil of a new kind of early bird, called Yuezhuornis. The surprise: it couldn't fly!

But why? Was Yuezhuornis still at the start of the evolutionary journey to becoming a flyer, or was it a youngster whose wings hadn't yet formed, or something else entirely?

The Evolution of Birds

All the way back in 1860, a year after Darwin's publication 'On the Origin of Species', someone in the Jurassic Solnhofen Limestone bed in Bavaria, Germany, discovered a single fossilized feather. A year later, the first of many Archaeopteryx fossils would be discovered in Late Jurassic rock layers roughly 163 to 145 million years old.

The fossils showed that birds had first evolved during the Mesozoic, the age of dinosaurs, roughly 252 to 66 million years ago.

Now, scientists agree birds are dinosaurs, descendants of carnivorous dinosaurs similar to species like Velociraptor and Deinonychus.

In the wider family tree, the group that includes all modern birds and their ancient relatives, including Archaeopteryx, is called Avialae.

Their closest relatives are thought to be feathered, ground-dwelling dinosaurs such as troodontids, dromaeosaurs, and unenlagiids. The first known winged birds (avialans) began flapping around during the Late Jurassic.

Since 2009, researchers have uncovered a proverbial flock of early fossil birds, especially in China from different Late Jurassic sites. Among them is the so-called Yanliao Fauna, a collection of ~164-million-year-old fossils from various animals, including early birds like Anchiornis huxleyi.

These early birds suggest that the ability to fly may have evolved a few million years earlier than Archaeopteryx had initially suggested.

Now, a new fossil from the so-called Zhenghe Fauna, around 149 million years old, adds to the long and complex evolution of avialans.

Describing an Oddity

Researchers uncovered the new fossil in the summer of 2024 near Yangyuan Village, roughly 4.5 km from the main Zhenghe Fauna dig site in Fujian Province. It came from the Nanyuan Formation, dated to roughly 148-150 million years ago. Those same layers produced early birds such as Fujianvenator, Baminornis, and Zhengheornis.

By examining a slice of shinbone, the researchers think that the bone had slowed or stopped growing, suggesting it was either an adult or subadult. The creature may have weighed around 820 grams. From the tip of its snout to the end of its tail, it was roughly 50 cm long.

That made it about the same size as Archaeopteryx. Unlike Archaeopteryx, however, it had short wings, more akin to carnivorous dinosaurs than birds, and slender, long legs.

All three fingers had strong, curved talons, and its feet likely had a long second claw eerily similar to a raptor's 'killing claw'.

Like the early bird Anchiornis and troodontids, its front teeth were tightly packed. Unlike any known bird, it also had saw-like edges, like mini serrated knives, on the rear edges of its teeth.

Its shoulders and arms resembled those of its ground-dwelling ancestors, while its hips, shins, and feet resembled those of later birds.

This strange mix of archaic and more modern features made the fossil unlike anything else the researchers had found.

A Weird Cousin in the Family Tree

The fossil was deemed a new species and named Yuezhuornis yangyuanensis. Its name combines the Chinese word 'Yuezhuo', a mythological bird, sometimes described as one of the five Chinese 'phoenixes', and 'ornis', the Greek word for bird. 'Yangyuan' pays homage to the village near which it was found.

The strange mix of features suggested Yuezhuornis could not fly. In fact, it seems to have lived as a speedy ground hunter. Its long second claw was possibly used to grab and secure prey.

Then the researchers ran a phylogenetic (family tree) analysis. Surprisingly, it placed Yuezhuornis closer to modern birds than Archaeopteryx. This suggests the flightless Yuezhuornis was more closely related to modern birds than THE ancient bird relative Archaeopteryx.

According to the study, among its contemporaries, Yuezhuornis was most closely related to the poor flyer Zhengheornis, and lived alongside the swamp-dwelling Fujianvenator.

But what does all this mean?

It may mean what paleontologists have been wondering about for a long time: evolution (once again) is not simple. Things did not just go from the ground to the sky in one smooth motion.

The researchers suggest two possible explanations. Explanation a) flight evolved more than once, including in the Avialae group. In this scenario, Archaeopteryx and Anchiornis evolved to fly, and later, bird ancestors evolved to do it again, separately. It's not too implausible; bats (mammals), insects, and birds all evolved to fly independently.

The second possibility is that Yuezhuornis's ancestors could fly, but it reverted back to a flightless lifestyle. After all, not all animals that managed to evolve to live on land actually stayed on land (think dolphins and whales). If so, Yuezhuornis would be much like modern penguins or ostriches: birds with flying ancestors that, for one reason or another, evolved to stay grounded. Similarly, its closest known relative, Zhengheornis, was a flyer, a poor one, yes, but a flyer regardless. This suggests Yuezhuornis's ancestors might have been flyers too.

What's more, Yuezhuornis's skull resembles those of troodontids. For a long time, paleontologists have believed birds were more closely related to dromaeosaurs, like Velociraptor and Microraptor. Troodontids were small, bird-like, non-avian dinosaurs like Troodon.

That may suggest troodontids were the group most closely related to birds.

The discovery is fitting, as paleontologists have come to realize the ability to fly probably evolved multiple times in other groups of carnivorous dinosaurs closely related to birds, such as Microraptor.

And evolving the ability to fly wasn't seamless; some remained clumsy flyers, like Zhengheornis, while others may have reverted to the lifeways of their ground-dwelling ancestors. All the while, many of their relatives, like Baminornis, had successfully taken to the sky.

It's easy to think the whole point of being a bird or evolving wings is to fly. But flying may have been just one of many ways evolution filled an empty niche. With every new fossil, paleontologists are realizing that once birds and their ancestors appeared, it wasn't simply a race to dominate the skies. It was a question of what worked best at the time, and for Yuezhuornis, the answer seems to have been to stay on the ground.

It might also help clarify birds' messy family history. Birds are generally thought to be closest to dromaeosaurs, but new evidence may suggest otherwise. It would be like finding out your cousin isn't Uncle John's kid after all, but your great-aunt's grandchild. That detail would change a whole branch of your family tree.

Now, the Cat TV subscription has run out, and it's about time I renew it.

Do you think Yuezhuornis belonged to a line of birds that had not yet evolved to fly, or to one that had given up flying?

Let me know what you think, and if you'd like to support this blog and the person writing it, you can chip in once, monthly, or yearly. Only if you'd like to.

References

Novas, F. E. (2026, October 14). Some Jurassic period birds were flightless. Nature, 658(8136), 609–610. https://doi.org/10.1038/d41586-026-02645-8

Xu, L., Wang, M., Lin, G. et al. Jurassic flightless bird reveals early ecological diversity of avialans. Nature 658, 690–697 (2026). https://doi.org/10.1038/s41586-026-10972-z