Jurassic flightless bird reveals early ecological diversity of avialans

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.

For More information, please visit:https://www.nature.com/articles/s41586-026-10972-z#Fun

Published: 14 October 2026

DOI:10.1038/s41586-026-10972-z

Disclaimer:

Partial content of this page is transferred from the network, only for the use of scientific communication, if there is infringement, please contact us to delete. See the Privacy Policy for more information.