07/14/2026
A newly discovered Jurassic bird is helping answer one of the longest-standing questions in bird evolution.
Paleontologists have described Zhengheornis buyu, a bird that lived approximately 148β150 million years ago in what is now Fujian Province, China.
Unlike earlier birds such as Archaeopteryx, which had long, dinosaur-like tails with 23β24 caudal vertebrae, Zhengheornis buyu had only 15 caudal vertebrae. However, those vertebrae remained separate and had not yet fused into a pygostyle-the compact tailbone that supports the fan-shaped tail feathers of modern birds.
For decades, many evolutionary biologists questioned whether this transitional stage had ever existed because no fossil had clearly documented it. This discovery provides the first clear evidence that tail shortening preceded the evolution of the pygostyle, showing that one of the defining features of modern birds evolved through multiple evolutionary steps rather than all at once.
The fossil also reveals that birds were already undergoing significant adaptive diversification by the end of the Jurassic, highlighting how rapidly early avian evolution was unfolding.
Published in Science Advances, Zhengheornis buyu represents one of the most significant recent discoveries for understanding how the tails of dinosaurs gradually evolved into those of modern birds.
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