Open Paleo

Jianianhualong

Xu et al., 2017

Named after Jianianhua (the company that funded the research) combined with Chinese long (dragon); meaning "Jianianhua dragon"

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Jianianhualong is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, Jianianhualong tengi, named in 2017 by Xu Xing and colleagues based on an articulated skeleton preserving feathers. The feathers at the middle of the tail of Jianianhualong are asymmetric, being the first record of asymmetrical feathers among the troodontids. Despite aerodynamic differences from the flight feathers of modern birds, the feathers in the tail vane of Jianianhualong could have functioned in drag reduction while the animal was moving. The discovery of Jianianhualong supports the notion that asymmetrical feathers appeared early in the evolutionary history of the Paraves.

Under dispute

Jianianhualong is consistently recovered as a basal troodontid, but analyses split on whether it belongs to Sinovenatorinae. Hartman and colleagues (2019), Sellés and colleagues (2021) and Kubota and colleagues (2024) place it within the subfamily, whereas Cau and Madzia (2021), Pei and colleagues (2021) and Wang and colleagues (2023) recover it outside; its describers placed it crownward of Mei and Sinovenator (Xu and colleagues, 2017).

Diagnosis

  1. Maxillary rostral ramus triangular in outline and relatively high dorsoventrally
  2. Maxillary ascending process extending posterodorsally at high angle (~45° to maxillary ventral margin)
  3. Long manual phalanx II-1 with prominent proximoventral heel and large groove along medial surface
  4. Highly elongated manual phalanx III-2 (slightly longer than metacarpal III)
  5. Ilium with slightly concave dorsal margin in lateral view
  6. Metatarsal IV without prominent ventral flange

Species

Jianianhualong tengi Xu et al., 2017

Type species

Named for Ms. Teng Fangfang, who acquired the specimen and made it available for study.

Holotype
DLXH 1218 , Xinghai Paleontological Museum of Dalian
Material
Nearly complete articulated skeleton preserving feathers, missing only the end of the tail
Horizon
Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Baicaigou, Liaoning, China

References

  1. Xu, X.; Currie, P.; Pittman, M.; Xing, L.; Meng, Q.; Lü, J.; Hu, D.; Yu, C. (2017). Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features. Nature Communications 8(1). Springer Science and Business Media LLC. doi:10.1038/ncomms14972

    Named Jianianhualong and recovered it crownward of Mei and Sinovenator.

    xu2017b
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026c
  3. Cau, A.; Madzia, D. (2021). The phylogenetic affinities and morphological peculiarities of the bird-like dinosaur Borogovia gracilicrus from the Upper Cretaceous of Mongolia. PeerJ 9: e12640. PeerJ. doi:10.7717/peerj.12640

    Recovered Jianianhualong outside Sinovenatorinae.

    cau2021a
  4. Hartman, S.; Mortimer, M.; Wahl, W. R.; Lomax, D. R.; Lippincott, J.; Lovelace, D. M. (2019). A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ 7: e7247. PeerJ. doi:10.7717/peerj.7247

    Recovered Jianianhualong as a basal troodontid within Sinovenatorinae.

    hartman2019a
  5. Sellés, A. G.; Vila, B.; Brusatte, S. L.; Currie, P. J.; Galobart, À. (2021). A fast-growing basal troodontid (Dinosauria: Theropoda) from the latest Cretaceous of Europe. Scientific Reports 11(1). Springer Science and Business Media LLC. doi:10.1038/s41598-021-83745-5

    Recovered Jianianhualong within Sinovenatorinae.

    sellés2021a
  6. Kubota, K.; Kobayashi, Y.; Ikeda, T. (2024). Early Cretaceous troodontine troodontid (Dinosauria: Theropoda) from the Ohyamashimo Formation of Japan reveals the early evolution of Troodontinae. Scientific Reports 14(1). Springer Science and Business Media LLC. doi:10.1038/s41598-024-66815-2

    Recovered Jianianhualong within Sinovenatorinae.

    kubota2024a
  7. Pei, R.; Qin, Y.; Wen, A.; Zhao, Q.; Wang, Z.; Liu, Z.; Guo, W.; Liu, P.; Ye, W.; Wang, L.; Yin, Z.; Dai, R.; Xu, X. (2021). A new troodontid from the Upper Cretaceous Gobi Basin of inner Mongolia, China. Cretaceous Research 130. Elsevier BV. doi:10.1016/j.cretres.2021.105052

    Recovered Jianianhualong outside Sinovenatorinae.

    pei2021a
  8. Wang, X.; Cau, A.; Wang, Z.; Yu, K.; Wu, W.; Wang, Y.; Liu, Y. (2023). A new theropod dinosaur from the Lower Cretaceous Longjiang Formation of Inner Mongolia (China). Cretaceous Research 151. Elsevier BV. doi:10.1016/j.cretres.2023.105605

    Recovered Jianianhualong outside Sinovenatorinae.

    wang2023a