New Jurassic Bird Had Teeth and a Sickle-Shaped “Killer” Claw

Paleontologists have described a new genus and species of early bird from the Late Jurassic Zhenghe Fauna in southeastern China. The flightless bird had tightly packed, serrated teeth and a large, sickle-shaped claw—features more commonly associated with small predatory dinosaurs.

Yuezhuornis yangyuanensis lived about 150 million years ago

The newly described species, Yuezhuornis yangyuanensis, lived in what is now China approximately 150 million years ago, during the Late Jurassic period.

The fossil comes from the Zhenghe Fauna, a recently recognized collection of Jurassic fossils that has produced some of the earliest known bird species, including Baminornis and Jianianhualong.

The holotype specimen of Yuezhuornis yangyuanensis was discovered in the Nanyuan Formation near Yangyuan Village in Fujian Province, China.

A bird with dinosaur-like teeth and feet

“When we investigated Yuezhuornis yangyuanensis, we were shocked by its unusual combination of features,” said Dr. Ming Wang, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences.

The animal had bird-like hips and hind legs, but it also possessed tightly packed, serrated teeth and a highly elastic second toe ending in a sickle-shaped claw.

These characteristics are typical of deinonychosaurs, a group of predatory dinosaurs that includes dromaeosaurs and troodontids.

“It has a bird-like pelvis and hindlimb structure, but retains the specialized predatory feet and teeth of a small carnivorous dinosaur,” Dr. Wang said.

“This shows that early bird evolution was much more complex than we previously realized.”

What the fossil reveals about early bird evolution

Evolutionary analysis placed Yuezhuornis yangyuanensis among the earliest branches of the bird lineage, near Archaeopteryx and as a sister taxon to Baminornis.

Its forelimbs were noticeably short, a common condition among non-avian theropods, and its limb proportions were similar to those of land-dwelling birds.

“The results consistently showed that Yuezhuornis yangyuanensis lies firmly just above birds—a group that includes living birds and their extinct relatives—Archaeopteryx and as a sister taxon to Baminornis,” said Dr. Zhonghe Zhou, also from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences.

The team’s study was published in the journal Nature.

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L. Shu et al. 2026. Jurassic flightless birds reveal early ecological diversity of birds. Nature 658, 690–697; doi: 10.1038/s41586-026-10972-z