Open Paleo

Shuangbaisaurus

Wang et al., 2017 SHONG-by-SOR-us Disputed

From "Shuangbai" (Shuangbai County in Yunnan, China, where the holotype was found) and Greek "sauros" (lizard); meaning "Shuangbai lizard".

201.4–199.5 million years ago Hettangian, Early Jurassic
Early Jurassic stages

Shuangbaisaurus is a genus of theropod dinosaur, possibly a junior synonym of Sinosaurus. It lived in the Early Jurassic of Yunnan Province, China, and is represented by a single species, S. anlongbaoensis, known from a partial skull. Like the theropods Dilophosaurus and Sinosaurus, Shuangbaisaurus bore a pair of thin, midline crests on its skull. Unusually, these crests extended backwards over the level of the eyes, which, along with the unusual orientation of the jugal bone, led the describers to name it as a new genus. However, Shuangbaisaurus also possesses a groove between its premaxilla and maxilla, a characteristic which has been used to characterize Sinosaurus as a genus. Among the two morphotypes present within the genus Sinosaurus, Shuangbaisaurus more closely resembles the morphotype that is variably treated as a distinct species, S. sinensis, in its relatively tall skull.

Under dispute

Shuangbaisaurus anlongbaoensis is a basal neotheropod described as a distinct crested theropod close to Sinosaurus and Dilophosaurus (Wang and colleagues, 2017). Its suggested synonymy with Sinosaurus triassicus is unpublished, and Zhang and colleagues (2023) keep it valid. It tracks the uncertain position of Sinosaurus and is placed conservatively at Neotheropoda incertae sedis.

Diagnosis

  1. Parasagittal crests present at least along the orbital dorsal rims (supraorbital crests spanning the entire dorsal rims of the orbits)
  2. Premaxillary body higher than long, with ventral border of the preserved dorsal rim approximately level with the ventral border of the antorbital fenestra
  3. Ventral edge of the premaxilla notably elevated, higher than the ventral edge of the maxilla, placing the last two premaxillary teeth above the maxillary ventral edge
  4. Small, round upper temporal fenestra with diameter shorter than the transverse width of the parietals in between and about half the length of the skull table posterior to the orbit
  5. Quadratojugal and posterior process of jugal directed posteroventrally

Species

Shuangbaisaurus anlongbaoensis Wang et al., 2017 Disputed

Type species

Named for Anlongbao Town in Shuangbai County, near where the holotype was recovered; the name literally means "dragon-placing fort".

Holotype
CPM C2140ZA245 , Chuxiong Prefectural Museum
Material
Partial skull with associated lower jaw, missing the nasals and the dorsal portions of the premaxillae, maxillae, and lacrimals.
Horizon
lower Fengjiahe Formation, Hettangian, Early Jurassic , 201.4–199.5 million years ago
Locality
Liuna Village, Anlongbao Town, Yunnan, China

References

  1. Wang, G. F.; You, H. L.; Pan, S. G.; Wang, T. (2017). A new crested theropod dinosaur from the Early Jurassic of Yunnan Province, China. Vertebrata PalAsiatica 55(2): 177-186. wang2017b
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Lists Shuangbaisaurus as a junior synonym of Sinosaurus.

    jones2026c
  3. Zhang, Z. C.; Wang, T.; You, H. L. (2023). A new specimen of Sinosaurus triassicus (Dinosauria: Theropoda) from the Early Jurassic of Lufeng, Yunnan, China. Historical Biology 36(4): 857-871. doi:10.1080/08912963.2023.2190760

    Keeps Shuangbaisaurus valid, distinct from Sinosaurus.

    zhang2023a