Bashanosaurus
From Bashan (巴山, an ancient name for the Chongqing/Sichuan region of China, where the fossils were found) + Greek sauros (σαῦρος) meaning 'lizard'; overall meaning 'Bashan lizard'.
Bashanosaurus is an extinct genus of stegosaurian dinosaur from the Middle Jurassic (Bathonian age) Shaximiao Formation of Yunyang County, China. The genus contains a single species, Bashanosaurus primitivus, known from incomplete skeletons belonging to three individuals. It is one of the basalmost stegosaurs, as well as one of the oldest known stegosaurs, along with Adratiklit, Isaberrysaura, and Thyreosaurus.
Diagnosis
- Parapophyses of dorsal vertebrae elevated on stalks at the base of the transverse process, clearly visible in anterior and posterior views.
- Scapula blade is slender and flares distally (ratio of maximum to minimum blade height ~3.4), unlike other stegosaurs where the blade does not expand distally.
- Acromial process of the scapula is small, triangular, and poorly developed, less developed than in Huayangosaurus.
- Fourth trochanter of the femur is positioned below the middle of the shaft, distinct from stegosaurs where it is at midshaft or poorly developed.
- Bases of dermal plates are strongly convex and transversely thickened, separated from the anterior/posterior plate margins by a distinct groove.
Species
Bashanosaurus primitivus Dai et al., 2022
Type species
References the fact that Bashanosaurus is among the earliest diverging stegosaurians.
- Holotype
- CLGPR V00006-1 , Chongqing Laboratory of Geoheritage Protection and Research
- Material
- Partial individual comprising one dorsal vertebra, two caudal vertebrae, right scapula, right coracoid, left femur, left tibia, left fibula, one metatarsal, three pieces of dermal armor (1 plate and 2 spines) and some ribs.
- Horizon
- lower Shaximiao Formation, Bajocian, Middle Jurassic , 170.9–168.2 million years ago
- Locality
- Laojun Village, Pu'an Township, Yunyang County, Chongqing, China Dai and colleagues (2022) date the holotype's quarry from U-Pb detrital zircon ages "for horizons bounding the holotypic quarry", which "indicate a Middle Jurassic (Bajocian) age".
References
- Dai, H.; Li, N.; Maidment, S. C. R.; Wei, G.; Zhou, Y.; Hu, X.; Ma, Q.; Wang, X.; Hu, H.; Peng, G. (2022). New stegosaurs from the Middle Jurassic Lower Member of the Shaximiao Formation of Chongqing, China. Journal of Vertebrate Paleontology 41(5). Informa UK Limited. doi:10.1080/02724634.2021.1995737 dai2022b
-
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the mass and hip height estimates, and the appearance features; the dorsal spines are from its reconstruction.
jones2026a