Open Paleo

Yunyangosaurus

Dai et al., 2020 yoon-YAHNG-oh-SAWR-us

Named for Yunyang County in Chongqing, China, where the fossils were found, combined with Greek 'sauros' meaning 'lizard'.

184.2–170.9 million years ago Toarcian–Aalenian, Early Jurassic–Middle Jurassic
Early Jurassic and Middle Jurassic stages

Yunyangosaurus is a genus of possible megalosauroid dinosaur from the Xintiangou Formation in Chongqing, China. The type and only species is Yunyangosaurus puanensis. The name was first published in the 2019 SVP abstract book by Dai (2019) before it was formally described by Dai and colleagues (2020).

Under dispute

Yunyangosaurus puanensis shares vertebral features with megalosauroids and was described as a possible basal megalosauroid, but in the numerical analysis it behaves as a wildcard: under equal weights it falls in an unresolved polytomy at the base of Tetanurae (collapsing Megalosauroidea and Coelurosauria), and only under implied weighting does it nest within Megalosauroidea (Dai and colleagues, 2020). It is placed conservatively at Tetanurae incertae sedis.

Diagnosis

  1. Mediolateral width of axial centrum tapers ventrally, resulting in subtriangular outline in posterior view
  2. Axis with accessory medial spinopostzygapophyseal lamina
  3. Ball-like structure at anterior margin base of axial neural spine
  4. Cervical epipophyses prominent and posteriorly oriented
  5. Posterior cervical and anterior dorsal vertebrae with transversely bifurcated neural spines
  6. Distinctive fossae immediately ventral to dorsal parapophyses

Species

Yunyangosaurus puanensis Dai et al., 2020

Type species

Named for Pu'an town in Yunyang County, Chongqing, China, the locality where the holotype specimen was found.

Holotype
CLGPR V00002 , Chongqing Laboratory of Geoheritage Protection and Research
Material
Partial skeleton comprising 11 presacral vertebrae, cervical and dorsal ribs, and chevrons
Horizon
upper Xintiangou Formation, Toarcian–Aalenian, Early Jurassic–Middle Jurassic , 184.2–170.9 million years ago
Locality
Laojun Village, Pu'an Township, Yunyang County, Chongqing, China

References

  1. Dai, H.; Benson, R.; Hu, X.; Ma, Q.; Tan, C.; Li, N.; Xiao, M.; Hu, H.; Zhou, Y.; Wei, Z.; Zhang, F.; Jiang, S.; Li, D.; Peng, G.; Yu, Y.; Xu, X. (2020). A new possible megalosauroid theropod from the Middle Jurassic Xintiangou Formation of Chongqing, People's Republic of China and its implication for early tetanuran evolution. Scientific Reports 10(1). Springer Science and Business Media LLC. doi:10.1038/s41598-019-56959-x dai2020a
  2. Dai, H.; Xu, X. (2019). A new megalosaurid theropod from the Middle Jurassic Xintiangou Formation of Chongqing, People's Republic of China and its implication for early tetanuran evolution. Society of Vertebrate Paleontology, 79th Annual Meeting, Program and Abstracts 79A: 86. dai2019a