Jurassic Bird Fossil Shows 15-Vertebra Tail Shortened Before Pygostyle Fusion
Updated
Updated · Sci.News · Jul 7
Jurassic Bird Fossil Shows 15-Vertebra Tail Shortened Before Pygostyle Fusion
3 articles · Updated · Sci.News · Jul 7
Summary
Zhengheornis buyu, described in Science Advances, preserves a short tail with 15 separate vertebrae, giving paleontologists a rare intermediate between long-tailed dinosaur ancestors and modern birds.
148-150 million-year-old remains from Fujian show tail shortening happened before vertebrae fused into a pygostyle, challenging the idea that both changes evolved simultaneously.
The 2024 find is estimated at 74 to 163 grams, making it the smallest known adult non-pygostylian theropod and adding a fourth bird taxon to the Zhenghe Fauna.
Its mixed anatomy and unclear tree- or ground-dwelling adaptations, alongside nearby species such as the cursorial Fujianvenator, suggest early birds were already diversifying ecologically by the end of the Jurassic.
A tiny Jurassic bird and its four-winged predator were found. What does their relationship reveal about ancient ecosystems?
How did a bird with a tail once deemed 'biologically impossible' reshape the story of early flight?
Unveiling the Avian Tail Mystery: *Zhengheornis buyu* and the Stepwise Evolution of Birds in the Late Jurassic
Overview
A major paleontological breakthrough was made in July 2026 with the discovery of Zhengheornis buyu in Zhenghe County, China. This ancient bird fossil, dating back 149 million years, was described by Min Wang and colleagues and stands out for its tail made of 15 unfused vertebrae. Unlike modern birds, which have a fused tailbone called a pygostyle, Zhengheornis buyu shows that tail shortening happened before this fusion. Because fossils showing this transition are extremely rare, this find provides the first direct evidence for a key step in bird evolution, helping to solve a long-standing mystery.