Open Paleo

Wannanosaurus

Hou, 1977 WAHN-NAHN-o-SAWR-us

Named for Wannan (southern Anhui), the region of China where the fossils were discovered, combined with Greek 'sauros' meaning 'lizard'.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Wannanosaurus is a genus of basal pachycephalosaurian dinosaur from the Campanian-aged (Upper Cretaceous) Xiaoyan Formation, in what is now Anhui, China. The type species Wannanosaurus yansiensis was described by Hou Lian-Hai in 1977.

Diagnosis

  1. Well-developed supratemporal fenestra (relatively large and elliptical)
  2. Cranial roof completely flattened, not domed
  3. Osseous tuberosities small and densely packed
  4. Forelimb short, humerus approximately half the length of femur
  5. Mandibular dentition long, exceeding half the length of mandible
  6. Distinct retroarticular process on mandible

Species

Wannanosaurus yansiensis Hou, 1977

Type species

Named for Yansi, the locality in Anhui Province, China, where the holotype was discovered.

Holotype
IVPP V4447 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Right posterior skull cap, left jugal, complete left mandible with teeth, left humerus, pair of femora, right tibia, portion of ilium, and cervical vertebra
Horizon
upper Xiaoyan Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Yansi, Anhui, China

References

  1. Hou, L. H. (1977). A new primitive Pachycephalosauria from Anhui, China. Vertebrata PalAsiatica 15(3): 198-202. hou1977a
  2. Schott, R. K.; Evans, D. C. (2016). Cranial variation and systematics of Foraminacephale brevis gen. nov. and the diversity of pachycephalosaurid dinosaurs (Ornithischia: Cerapoda) in the Belly River Group of Alberta, Canada. Zoological Journal of the Linnean Society. Oxford University Press (OUP). doi:10.1111/zoj.12465

    Recovered Wannanosaurus as basal-most pachycephalosaur outside Pachycephalosauridae.

    schott2016a
  3. Chinzorig, T.; Takasaki, R.; Yoshida, J.; Tucker, R. T.; Buyantegsh, B.; Mainbayar, B.; Tsogtbaatar, K.; Zanno, L. E. (2025). A domed pachycephalosaur from the early Cretaceous of Mongolia. Nature 646(8087): 1138-1145. Springer Science and Business Media LLC. doi:10.1038/s41586-025-09213-6

    Recovered Wannanosaurus as the earliest-branching pachycephalosaurian, but cautions that the immaturity of the holotype may influence its position.

    chinzorig2025a