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| Yuezhuornis yangyuanensis L. Xu, Wang, G. Lin, Dong, Deng, X. Xu, Du, M. Lin, Chen & Zhou, 2026 Life reconstruction by Min Wang. |
Abstract
The origin and early diversification of birds remain highly debated in vertebrate evolution. Although estimates of the evolutionary timescales suggest a Jurassic period radiation, a profound scarcity of fossils from this period has hampered how the distinctive bird bauplan was assembled. Selection for powered flight has been viewed as the primary driver of early avialan skeletal modifications, attesting to the independent occurrences of aerodynamic features among paravian lineages. Here we report on the discovery of a Late Jurassic avialan, Yuezhuornis yangyuanensis, gen. et sp. nov., from the Zhenghe Fauna of southeastern China. As one of the earliest diverging avialans, Y. yangyuanensis exhibits a striking mosaic of features, combining a mixture of avialan- and troodontid-like cranial characters, paired with derived postcranial traits and a deinonychosaur-like hyperextensible second pedal digit. Phylogenetically informed analyses show that Y. yangyuanensis possesses markedly short forelimbs—a condition present widely among non-avialan theropods. These findings provide strong evidence for a terrestrial, flightless lifestyle of Y. yangyuanensis. Our study demonstrates that evolution works intensively as exemplified by the occurrence of several, divergent ecological pathways being exploited in the initial diversification of birds.
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| Life reconstruction of the Late Jurassic bird Yuezhuornis yangyuanensis. Artwork by Min Wang. |
Liming Xu, Min Wang, Ganmin Lin, Liping Dong, Ke Deng, Xing Xu, Honggang Du, Min Lin, Runsheng Chen and Zhonghe Zhou. 2026. Jurassic flightless Bird reveals early Ecological Diversity of avialans. Nature. 658; 690–697. DOI: doi.org/10.1038/s41586-026-10972-z [14 October 2026]
Liming Xu (徐立明), Min Wang (王敏), Ganmin Lin (林淦旻), Liping Dong (董丽萍), Ke Deng (邓克), Xing Xu (徐星), Honggang Du (杜红岗), Min Lin (林敏), Runsheng Chen (陈润生) & Zhonghe Zhou (周忠和)