A Jurassic bird fossil from southeastern China suggests that some of the earliest birds were already adapted to life on the ground. Researchers described Yuezhuornis yangyuanensis in Nature on October 14, 2026. Its unusually short wings provide evidence for a largely terrestrial, possibly flightless lifestyle, challenging the idea that early bird evolution mainly favored better flight.
The crow-sized animal lived about 148 million to 150 million years ago in what is now Fujian province. Scientists from the Chinese Academy of Sciences and the Fujian Institute of Geological Sciences studied the fossil from the Zhenghe Fauna. Jurassic bird fossils are rare, leaving substantial gaps in knowledge of how birds first diversified.
According to Nature's research summary, the bird weighed an estimated 821 grams and had forelimbs roughly a third shorter than its hind limbs. Comparisons with 377 living bird species linked its proportions most closely to ground-dwelling birds such as pheasants. These measurements underpin the team's interpretation of its lifestyle rather than direct evidence of its behavior.
The researchers also identified closely packed, serrated teeth and a flexible second toe bearing a sickle-shaped claw, alongside a birdlike pelvis. The Chinese Academy of Sciences said evolutionary analyses placed the species within the group containing modern birds and their closest extinct relatives, slightly closer to modern birds than Archaeopteryx.
The study argues that early birds explored different ecological roles, including ones that did not favor flight. Although the paper supports a flightless interpretation, researcher Min Wang told Reuters that mostly running with occasional short flights was also plausible. The precise extent of its flying ability therefore remains uncertain.
Nature's summary cautions that the species is known from one incomplete specimen. Further fossils will be needed to clarify its way of life and evolutionary position. The discovery gives researchers a new basis for testing how diverse bird bodies and behaviors became near the beginning of their evolutionary history.
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