Open Paleo

Yizhousaurus

Zhang et al., 2018 YEEZ-hoo-SOR-us

Named for the Yizhou region (Chuxiong Yi Autonomous Region) of Yunnan, China, combined with Greek 'sauros' meaning 'lizard'.

199.5–192.9 million years ago Sinemurian, Early Jurassic
Early Jurassic stages

Yizhousaurus is a genus of basal sauropodiform dinosaurs which existed in what is now Lufeng Formation, Yunnan Province of southern China during the lower Jurassic period. Identified from a nearly complete and exquisitely preserved skeleton, it is the most complete basal sauropod currently known with intact skull. Although its name was revealed in a 2010 Geological Society of America abstract by Sankar Chatterjee, T. Wang, S.G. Pan, Z. Dong, X.C. Wu, and Paul Upchurch, it wasn't validly named and described until 2018. The type species is Yizhousaurus sunae.

Under dispute

Yizhousaurus sunae is a sauropodiform with a convergently sauropod-like skull. Zhang and colleagues (2018), describing the genus, recovered it within Sauropodiformes as a non-sauropodan sauropodomorph close to Anchisaurus and Mussaurus, nearer the base of Sauropoda than other Lufeng sauropodomorphs but not within Sauropoda itself.

Diagnosis

  1. Lateral plates appressed to labial sides of premaxillary and maxillary teeth but not dentary teeth
  2. Antorbital fenestra anteroposteriorly narrow and pipe-shaped in outline
  3. Lacrimal shaft vertical with respect to maxillary ramus
  4. Anterior tip of dentary anterodorsally curved over alveolar margin
  5. Tiny external mandibular fenestra approximately 5% of mandibular length
  6. Subelliptical cross-section of femoral midshaft with long axis oriented mediolaterally

Species

Yizhousaurus sunae Zhang et al., 2018

Type species

Named in honor of Professor Ai-Ling Sun for contributions to Chinese vertebrate paleontology, including the study of fossils from Lufeng.

Holotype
LFGT-ZLJ0033 , Lufeng World Dinosaur Valley
Material
Undistorted skeleton about 7m long, including well-preserved skull and mandible, mostly complete vertebral series (9 cervicals, 14 dorsals, 3 sacrals, 5 anterior caudals), pectoral and pelvic girdles, forelimbs and femora
Horizon
upper Zhangjiawa Member, Lufeng Formation, Sinemurian, Early Jurassic , 199.5–192.9 million years ago
Locality
Duwafang Village, Yunnan, China

References

  1. Zhang, Q. N.; You, H. L.; Wang, T.; Chatterjee, S. (2018). A new sauropodiform dinosaur with a 'sauropodan' skull from the Lower Jurassic Lufeng Formation of Yunnan Province, China. Scientific Reports 8(1). Springer Science and Business Media LLC. doi:10.1038/s41598-018-31874-9

    Erected Yizhousaurus and recovered it within Sauropodiformes as a non-sauropodan sauropodomorph, not within Sauropoda.

    zhang2018a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the body length and mass estimates.

    paul2024a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026b