Open Paleo

Abrosaurus

Ouyang, 1989 AB-ro-SAWR-us /ˌæbroʊˈsɔːrəs/

From Greek 'abros' meaning 'delicate' or 'dainty' and 'sauros' meaning 'lizard', referring to the delicate skull structure.

170.9–154.8 million years ago Bajocian–Oxfordian, Middle Jurassic–Late Jurassic
Middle Jurassic and Late Jurassic stages

Abrosaurus is a genus of macronarian sauropod dinosaur from the Middle Jurassic Period of what is now Asia. It is one of many dinosaurs found at the Dashanpu Quarry in the Sichuan Province of China. Like most sauropods, Abrosaurus was a quadrupedal herbivore. It was rather small for a sauropod, measuring no more than 9.1 meters (30 ft) long. Its head was boxy and topped with a tall, bony arch containing the nostrils. The generic name refers to the nature of the skull, with large openings separated by thin, bony struts. The only named species is A. dongpoi, named after eleventh-century Chinese poet Su Shi, also known as Su Dongpo, who was born in Sichuan.

Under dispute

Abrosaurus was described as a camarasaurid (Ouyang, 1989) but has not been included in a phylogenetic analysis. Upchurch and colleagues (2004) provisionally regard it as a basal macronarian, Wilson (2005) lists it among basal eusauropods, and Peng and colleagues (2005) assign it to Mamenchisauridae; undescribed cranial material limits its resolution.

Diagnosis

  1. Skull height/length index of 1:1.8, producing a lower and more elongated skull than other camarasaurids
  2. External nares larger than orbits and divided only by an extremely thin medial nasal crest
  3. Antorbital fenestra triangular and isosceles in shape, approximately half the size of the orbit
  4. Parietal extremely narrow with supratemporal fenestrae in relatively close proximity
  5. Premaxillary tooth count of 5, unrecorded in any other sauropod
  6. Dentary distinctly dorsoventrally constricted at its midportion between the anterior end and the coronoid process

Species

Abrosaurus dongpoi Ouyang, 1989

Type species

Named for the eleventh-century Chinese poet Su Shi, also known as Su Dongpo, who was born in Sichuan, the province where the fossil was found.

Holotype
ZDM5038 , Zigong Dinosaur Museum
Material
Exceptionally complete skull
Horizon
lower Shaximiao Formation, Bajocian–Oxfordian, Middle Jurassic–Late Jurassic , 170.9–154.8 million years ago
Locality
Dashanpu Dinosaur Quarry, Sichuan, China

References

  1. Ouyang, H. (1989). [A new sauropod from Dashanpu, Zigong Co., Sichuan Province (Abrosaurus dongpoensis gen. et sp. nov.)]. Zigong Dinosaur Museum Newsletter 2: 10-14. ouyang1989a
  2. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  3. Upchurch, P.; Barrett, P. M.; Dodson, P. (2004). Sauropoda. The Dinosauria, Second Edition (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 259-322. University of California Press, Berkeley.

    Provisionally regards Abrosaurus as a basal macronarian.

    upchurch2004a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Treats Abrosaurus as Macronaria incertae sedis.

    jones2026b
  5. Wilson, J. A. (2005). Redescription of the Mongolian sauropod Nemegtosaurus mongoliensis Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous sauropod diversity. Journal of Systematic Palaeontology 3(3): 283-318. doi:10.1017/s1477201905001628

    Lists Abrosaurus among basal eusauropods.

    wilson2005a
  6. Peng, G.; Ye, Y.; Gao, Y.; Shu, C.; Jiang, S. (2005). Zìgòng dìqū zhū luó jì kǒnglóng dòngwù qún [Jurassic Dinosaur Faunas in Zigong]. 1-236. People's Publishing House, Sichuan Publishing Group.

    Assigns Abrosaurus to Mamenchisauridae.

    peng2005a