Open Paleo

Jianchangosaurus

Pu et al., 2013 JEE-EN-CHAN-go-SOR-us

Named after Jianchang County, Liaoning Province, China, where the type specimen was discovered; meaning "lizard from Jianchang County"

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

Jianchangosaurus is a genus of therizinosaurian dinosaur that lived approximately 126 million years ago during the early part of the Cretaceous Period from the Yixian Formation in what is now China. The type specimen, a juvenile, was discovered in Jianchang County, in the western part of Liaoning Province. It was described in 2013 by a team of paleontologists from the Henan Museum, who determined that it was among the most basal therizinosaurs.

Under dispute

Jianchangosaurus is recovered as one of the earliest-diverging therizinosaurs, between Falcarius and Beipiaosaurus (Pu and colleagues, 2013; Hartman and colleagues, 2019; Liao and colleagues, 2026). Cau (2024) treated its juvenile holotype as an immature Beipiaosaurus, coding the two in a single unit on the grounds that their differences are related to size and growth, and regarded Jianchangosaurus as a junior synonym; Liao and colleagues (2026) treat the two as distinct.

Diagnosis

  1. 27 Tightly packed maxillary teeth aligned along lateral edge
  2. Edentulous premaxilla
  3. Short diastema in anterior dentary tip
  4. Dentary teeth posterior to 7th position with reversed morphology (concave labial, convex lingual surfaces)
  5. Down-turned anterior dentary with rostral gap and inset tooth row by shelf
  6. Anterior caudal centra with oval cross-section and articular facets as tall as wide
  7. Anterior caudal neural spines with anterior and posterior alae
  8. Lack of prominent hypapophyses in anterior dorsal vertebrae
  9. Manual unguals weakly curved with weak flexor tubercles
  10. Straight ulnar shaft (not bowed)
  11. Jugal not participating in antorbital fenestra margin

Species

Jianchangosaurus yixianensis Pu et al., 2013

Type species

Named for the Yixian Formation, where the specimen was found.

Holotype
HGM 41HIII-0308A , Henan Geological Museum
Material
Nearly complete skeleton
Horizon
Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Niujiaogou, Liaoning, China

References

  1. Pu, H.; Kobayashi, Y.; Lü, J.; Xu, L.; Wu, Y.; Chang, H.; Zhang, J.; Jia, S. (2013). An Unusual Basal Therizinosaur Dinosaur with an Ornithischian Dental Arrangement from Northeastern China. PLoS ONE 8(5): e63423. Public Library of Science (PLoS). doi:10.1371/journal.pone.0063423

    Named Jianchangosaurus from a juvenile skeleton and recovered it as the sister of Therizinosauroidea.

    pu2013a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the appearance features. Treats Jianchangosaurus as a valid basal therizinosaur.

    jones2026c
  3. Cau, A. (2024). A Unified Framework for Predatory Dinosaur Macroevolution. Bollettino della Società Paleontologica Italiana 63(1): 1-19. doi:10.4435/BSPI.2024.08

    Coded the Jianchangosaurus holotype in the Beipiaosaurus unit as an immature individual, regarding Jianchangosaurus as a junior synonym.

    cau2024a
  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 Falcarius, Jianchangosaurus, Beipiaosaurus and Alxasaurus as successively closer to therizinosaurids.

    hartman2019a
  5. Liao, C. C.; Freimuth, W. J.; Zanno, L. E.; Xu, X. (2026). A new therizinosaur from the Early Cretaceous Jehol Biota and ecomorphological patterns among early therizinosaurians. Journal of Systematic Palaeontology 24(2): 2710287. Informa UK Limited. doi:10.1080/14772019.2026.2710287

    Recovered Jianchangosaurus between Eshanosaurus and Kayrasaurus, apart from Beipiaosaurus.

    liao2026a
  6. Kobayashi, Y.; Zelenitsky, D. K.; Fiorillo, A. R.; Chinzorig, T. (2025). Didactyl therizinosaur with a preserved keratinous claw from the Late Cretaceous of Mongolia. iScience 28(4). Elsevier BV. doi:10.1016/j.isci.2025.112141

    Retains Jianchangosaurus as a separate terminal.

    kobayashi2025a