Open Paleo

Daanosaurus

Ye et al., 2005 DAH-no-SOR-us

Named after Da'an District in Zigong, Sichuan Province, China, where the Zigong Dinosaur Museum is located, + Greek sauros ('lizard'), meaning 'Da'an lizard'.

154.8–143.1 million years ago Kimmeridgian–Tithonian, Late Jurassic
Late Jurassic stages

Daanosaurus was a genus of sauropod dinosaur which lived during the Late Jurassic (Oxfordian–Tithonian stage, about 163–145 mya). It lived in what is now China (Sichuan Province), and was similar to Bellusaurus. Daanosaurus is known only from a partial skeleton of a juvenile, and it has been debated whether the specimen may be a juvenile mamenchisaurid.

Under dispute

Daanosaurus, based on a juvenile, was originally described as a macronarian (Bellusaurinae within Brachiosauridae) by Ye and colleagues (2005), but Moore and colleagues (2023) treat it as a juvenile mamenchisaurid-grade form. Jones (2026) lists it among mamenchisaurids while documenting the macronarian alternative.

Diagnosis

  1. Axis extremely short and high, with centrum length only 60% of total vertebral height — far lower ratio than other known sauropods.
  2. Cervical neural spines low with straight upper borders and prominent anteroposterior extension; posterior cervical spines transversely widened into near-square shape but not bifurcated.
  3. Anterior processes of mid-cervical ribs bifurcate (forked apex), a condition previously known only from Mamenchisaurus youngi.
  4. Dorsal neural spines form transversely broad plate-like structures without bifurcation.
  5. Chevrons Y-shaped with haemal canal not closed (blood vessel foramina open) at proximal end.
  6. Cavities in cervical neural arches highly developed, including prominent prezygapophysial cavities in mid-cervical vertebrae and large deep postspinal cavities.

Species

Daanosaurus zhangi Ye et al., 2005

Type species

Named for Zhang Aiping, former Minister of National Defense of China.

Holotype
ZDM 0193 , Zigong Dinosaur Museum
Material
Incomplete skeleton: fragmented skull, 20+ pre-sacral vertebrae, one chevron, complete right femur, partial ribs.
Horizon
upper Shaximiao Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Yongan Town, Sichuan, China

References

  1. Ye, Y.; Gao, Y. H.; Jiang, S. (2005). A new genus of sauropod from Zigong, Sichuan. Vertebrata PalAsiatica 43(3): 175-181.

    Original description; assigned Daanosaurus to Bellusaurinae within Brachiosauridae (Macronaria).

    ye2005a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026b
  3. Moore, A. J.; Barrett, P. M.; Upchurch, P.; Liao, C. C.; Ye, Y.; Hao, B.; Xu, X. (2023). Re-assessment of the Late Jurassic eusauropod Mamenchisaurus sinocanadorum Russell and Zheng, 1993, and the evolution of exceptionally long necks in mamenchisaurids. Journal of Systematic Palaeontology 21(1). doi:10.1080/14772019.2023.2171818

    Treats Daanosaurus as a juvenile mamenchisaurid-grade form under its favored analysis.

    moore2023a