Open Paleo

Tugulusaurus

Dong, 1973 too-GOO-loo-SAWR-us

Named for the Tugulu Group geological formation of Xinjiang, China, where the fossils were found, combined with Greek 'sauros' meaning 'lizard'.

137.1–100.5 million years ago Valanginian–Albian, Early Cretaceous
Early Cretaceous stages

Tugulusaurus is a genus of coelurosaurian theropod dinosaur, belonging to the Alvarezsauroidea, that is known from the Early Cretaceous Tugulu Group in the Urhe area of China. It was one of the first members of Alvarezsauria ever discovered. The type and only known species is T. faciles.

Under dispute

Tugulusaurus faciles was long treated as an enigmatic coelurosaur or ornithomimosaur, and even as a nomen dubium, until its validity was reaffirmed by the redescription of Rauhut and Xu (2005). It has since been recovered as a basal alvarezsauroid by Xu and colleagues (2018) and within a Bannykus plus Tugulusaurus plus Xiyunykus clade by Meso and colleagues (2024), a placement adopted by Jones (2026).

Diagnosis

  1. Proximal mid-caudal vertebrae with the neural arch placed only on the anterior two thirds of the centrum, the centrum considerably broader than high (width to height ratio about 1.5) (autapomorphy)
  2. Caudal centra increasing rapidly in length toward the posterior
  3. Minimal length of the first metacarpal less than the width of that bone (autapomorphy)
  4. Tibia with a pronounced, semicircular lateral expansion of the lateral malleolus (autapomorphy)

Species

Tugulusaurus faciles Dong, 1973

Type species

From Latin 'facilis' meaning 'easily moving', referring to the agility of the animal as indicated by its delicate bones.

Holotype
IVPP V4025 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Fragmentary postcranial skeleton comprising caudal vertebrae, a dorsal rib, the first digits of both manus, and partial hindlimbs.
Horizon
Lianmuqin Formation, Valanginian–Albian, Early Cretaceous , 137.1–100.5 million years ago
Locality
Wuerho, field locality 64041-2, Xinjiang, China

References

  1. Dong, Z. (1973). [Dinosaurs from Wuerho]. Reports of Paleontological Expedition to Sinkiang (II): Pterosaurian Fauna from Wuerho, Sinkiang. Memoirs of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica 11: 45-52. dong1973a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Xu, X.; Choiniere, J.; Tan, Q.; Benson, R. B. J.; Clark, J.; Sullivan, C.; Zhao, Q.; Han, F.; Ma, Q.; He, Y.; Wang, S.; Xing, H.; Tan, L. (2018). Two Early Cretaceous Fossils Document Transitional Stages in Alvarezsaurian Dinosaur Evolution. Current Biology 28(17): 2853-2860.e3. Elsevier BV. doi:10.1016/j.cub.2018.07.057

    Recovered Tugulusaurus as a basal alvarezsauroid outside more derived alvarezsaurid lineages.

    xu2018c
  4. Rauhut, O. W. M.; Xu, X. (2005). The small theropod dinosaurs Tugulusaurus and Phaedrolosaurus from the early Cretaceous of Xinjiang, China. Journal of Vertebrate Paleontology 25(1): 107-118. Informa UK Limited. doi:10.1671/0272-4634(2005)025[0107:tstdta]2.0.co;2

    Revalidated Tugulusaurus, previously an enigmatic coelurosaur, and gives its age as "?Valanginian-Albian".

    rauhut2005c
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Treats Tugulusaurus as a basal alvarezsauroid.

    jones2026c
  6. Meso, J. G.; Pol, D.; Chiappe, L.; Qin, Z.; Díaz-Martínez, I.; Gianechini, F.; Apesteguía, S.; Makovicky, P. J.; Pittman, M. (2024). Body size and evolutionary rate analyses reveal complex evolutionary history of Alvarezsauria. Cladistics 41(2): 135-155. Wiley. doi:10.1111/cla.12600

    Recovered Tugulusaurus within a Bannykus plus Tugulusaurus plus Xiyunykus clade.

    meso2024a