Overview
- The study published Wednesday in Nature formally names Yuezhuornis yangyuanensis and describes a nearly complete skeleton found in 2024 in the Upper Jurassic Zhenghe Fauna of Fujian, China.
- Researchers estimate the animal weighed about 0.8 kilograms and had forelimbs roughly one‑third shorter than its hind limbs, a limb ratio that clusters with modern ground‑running birds such as pheasants.
- Yuezhuornis shows a mosaic of features including serrated teeth, a bird‑like pelvis and a hyperextensible second toe with a sickle claw, traits that point to at least partial carnivory and active ground hunting.
- Authors and outside experts say the specimen undermines a simple, linear model of early bird evolution by showing that some early avialans reduced flight ability or evolved non‑flying, ground‑based lifestyles.
- Because Jurassic avialan fossils are scarce, the paper calls for more finds and broader phylogenetic sampling to clarify whether powered flight evolved multiple times or was lost in some lineages and to map niche partitioning among early birds and small dinosaurs.