Open Paleo

Yuezhuornis

Xu et al., 2026

"Yuezhuo" (Mandarin), a Chinese mythological bird, + "ornis" (Greek), bird

154.8–143.1 million years ago Kimmeridgian–Tithonian, Late Jurassic
Late Jurassic stages

Yuezhuornis is an extinct genus of basal avialan known from the Late Jurassic (Kimmeridgian–Tithonian ages) Nanyuan Formation of China. The genus contains a single species, Yuezhuornis yangyuanensis, known from a partial skeleton and skull. It has significantly shorter arms than its closest relatives—being proportionally more similar to many non-avialan theropods—implying it was incapable of flight. It was a close relative of Zhengheornis, which is known from the same locality.

Diagnosis

  1. Maxillary teeth serrated distally and not constricted below the crowns (possible autapomorphy)
  2. Slender jugal with a reduced quadratojugal process and a blunt-ended postorbital process (possible autapomorphy)
  3. Penultimate manual phalanges with enlarged ventral heels proximally (possible autapomorphy)
  4. Forelimb one-third shorter than the hind limb, with the humerus shorter than the femur
  5. Trapezoidal coracoid with an anterior surface sculpted by numerous pits
  6. Metatarsals II-IV not ginglymoid; pedal phalanx II-1 (or II-2) with a dorsally placed collateral ligament fossa and a large proximoventral heel

Species

Yuezhuornis yangyuanensis Xu et al., 2026

Type species

"yangyuan" (Mandarin), for Yangyuan Village, where the holotype was found

Holotype
IVPP V34427 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Incomplete, partially articulated skeleton of a subadult or adult, including the skull, cervical, dorsal and 17 caudal vertebrae, ribs, gastralia, furcula, coracoids, forelimbs, ilia, pubes, hind limbs and pedal phalanges
Horizon
lower Nanyuan Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
near Yangyuan Village, Zhenghe, Fujian, China Xu and colleagues (2026) correlate the horizon with the layers that yielded Fujianvenator, Baminornis and Zhengheornis. In Xu and colleagues' (2023) section those layers lie between a tuffite dated 150.2 ± 1.1 Ma and the ignimbrite over the fossil-bearing sediments, dated 148 ± 1.9 Ma: Kimmeridgian to Tithonian on the ICS chart v2024/12. The "Tithonian stage" both papers give belongs to an older chart.

References

  1. Xu, L.; Wang, M.; Lin, G.; Dong, L.; Deng, K.; Xu, X.; Du, H.; Lin, M.; Chen, R.; Zhou, Z. (2026). Jurassic flightless bird reveals early ecological diversity of avialans. Nature 658(8136): 690-697. Springer Science and Business Media LLC. doi:10.1038/s41586-026-10972-z xu2026b
  2. Xu, L.; Wang, M.; Chen, R.; Dong, L.; Lin, M.; Xu, X.; Tang, J.; You, H.; Zhou, G.; Wang, L.; He, W.; Li, Y.; Zhang, C.; Zhou, Z. (2023). A new avialan theropod from an emerging Jurassic terrestrial fauna. Nature 621(7978): 336-343. Springer Science and Business Media LLC. doi:10.1038/s41586-023-06513-7

    Dates the fossil-bearing layers of the lower Nanyuan Formation that the describing paper correlates with the holotype's horizon, and the ignimbrite that overlies them.

    xu2023a