Zigongosaurus

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Zigongosaurus
Temporal occurrence
Middle Jurassic ( Bathonian to Callovian )
168.3 to 163.5 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropodomorpha
Sauropods (Sauropoda)
Eusauropoda
Zigongosaurus
Scientific name
Zigongosaurus
Hou , Zhao & Chao, 1976
Art
  • Zigongosaurus fuxiensis

Zigongosaurus is a little-known genus of sauropod dinosaur from Central Jurassic China . The validity of this genus is controversial - so many researchers assume that the only species, Zigongosaurus fuxiensis , must actually beassumed to beeither Mamenchisaurus or Omeisaurus .

Research history and description

The only known fossils were found in 1974 by employees of the Chungking Natural History Museum from the Wujaiba Dam site in Zigong in the Chinese province of Sichuan . The site includes rocks of the Lower Shaximiao Formation , which can be dated from the Bathonian to Callovian . Among the finds are skull bones and bones of the residual skeleton that belonged to several different individuals. Under time pressure, only the most important fossils could be selected for preparation and subsequent description - in 1976 these fossils were scientifically described by the paleontologists Hou, Zhao and Chao in a brief description in Chinese as a new species and genus, Zigongosaurus fuxiensis . According to these researchers, the fossils resemble those of the Omeisaurus , but differ from them by the anterior caudal vertebrae, whose vertebral bodies were procoel (concave on the front and convex on the back) and their spinous processes less pronounced.

Dong (1983) provided the majority of the fossils of the species Omeisaurus junghsiensis . However , he attributed some remains of the skull (jawbones and basioccipital ) as well as a cervical vertebra ( axis ) to a new species - Omeisaurus fuxiensis . However, Dong was the only fossil of the material originally described as Zigongosaurus that could not assign a single upper jaw to Omeisaurus , but continued to carry it as Zigongosaurus fuxiensis . Thus, according to Dong, three sauropods were present in the Wujaiba Dam site: Omeisaurus junghsiensis , Omeisaurus fuxiensis and Zigongosaurus fuxiensis . McIntosh (1990) considers Zigongosaurus fuxiensis to be identical to Omeisaurus junghsiensis - so Zigongosaurus would be a younger synonym of Omeisaurus .

Zhang and Chen (1996) examined the fossils again and came to the opposite conclusion. As these researchers note, the posterior cervical vertebrae and the anterior vertebrae have slightly forked spinous processes - this feature, although less pronounced, is typical of Mamenchisaurus , but is absent in Omeisaurus . Consequently, these researchers attribute the sauropod material to the site of the genus Mamenchisaurus - as Mamenchisaurus fuxiensis . According to these researchers, M. fuxiensis was a medium to large-sized sauropod that compared to other Mamenchisaurus species was characterized by a relatively tall skull with a poorly developed snout. The spatula-shaped teeth were medium-sized, in the premaxillary there were 4 teeth on each side, in the upper jaw 12–14 and in the lower jaw 15–17.

Another study by Martin-Rolland (1999), however, considers Zigongosaurus to be a valid genus. The fossils would be clearly different from Mamenchisaurus , among other things in the less pronounced bifurcation of the vertebrae. A more recent study by Upchurch and colleagues (2004) follows the interpretation of Zhang and Chen and lists Zigongosaurus fuxiensis within the genus Mamenchisaurus .

Individual evidence

  1. ^ A b c Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324.
  2. ↑ L.-h. Hou, S.-w. Zhou, S.-c. Chao: [New discovery of sauropod dinosaurs from Sichuan]. In: Vertebrata PalAsiatica. Vol. 14, No. 3, 1976, ISSN  1000-3118 , pp. 160-165, digitized version (PDF; 1.11 MB) , (in Chinese language and writing).
  3. ↑ a b Zhiming Dong , Shiwu Zhou, Yihong Zhang: [Dinosaurs from the Jurassic of Sichuan]. In: Palaeontologica Sinica. No. 162 = New Series C, No. 23, 1983, pp. 1–136, (In Chinese language and writing; translation: Dinosaurs from the Jurassic of Sichuan. (PDF; 2.79 MB) ).
  4. ^ A b Donald F. Glut : Dinosaurs. The Encyclopedia. Supplement 2. McFarland, Jefferson NC 2002, ISBN 0-7864-1166-X , pp. 589-590.
  5. ^ John S. McIntosh: Sauropoda. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . University of California Press, Berkeley CA et al. 1990, ISBN 0-520-06726-6 , pp. 345-401, here p. 349.
  6. ^ Yihong Zhang, Wei Chen: Preliminary research on the classification of sauropods from Sichuan Basin, China. In: Michael Morales (Ed.): The Continental Jurassic. Transactions of the Continental Jurassic Symposium, October 21-23, 1996, Museum of Northern Arizona, Flagstaff, Arizona (= Museum of Northern Arizona. Bulletin Series. Vol. 60). Museum of Northern Arizona Press, Flagstaff AZ 1996, ISBN 0-89734-119-8 , pp. 97-107.