Key facts
- Fossil of Yuezhuornis yangyuanensis, the earliest known flightless bird, discovered in China.
- The bird lived approximately 150 million years ago.
- Yuezhuornis yangyuanensis had undersized wings and dinosaur-like features.
- Discovery challenges the paradigm that avian evolution was exclusively driven by flight.
Scientists in China have unearthed the fossil of Yuezhuornis yangyuanensis, a crow-sized bird that lived approximately 150 million years ago during the Jurassic Period. This discovery is significant as it represents the earliest known flightless bird, challenging long-held assumptions that flightlessness in birds was a secondary adaptation after flight was mastered. The fossil, found in Fujian Province, exhibits a mosaic of avian and dinosaurian traits, including undersized wings, serrated teeth, and a sickle-shaped claw on its second toe. Paleontologists suggest Yuezhuornis may have been more of a runner, potentially competing with small non-bird dinosaurs for prey. This finding alters the understanding of what early Jurassic birds looked like and suggests avian evolution was more complex than previously thought.