Zigongosaurus

Taxobox
name = Zigongosaurus
fossil_range = Middle Jurassic-Late Jurassic
regnum = Animalia
phylum = Chordata
classis = Sauropsid
superordo = Dinosauria
ordo = Saurischia
subordo = Sauropodomorpha
infraordo = Sauropoda
familia = uncertain
genus = "Zigongosaurus"
genus_authority = Hou, Zhao, and Chao, 1976 (also represented as Hou, Chao, and Chu, but they are the same authors)
subdivision_ranks = Species
subdivision =
* "Z. fuxiensis " Hou "et al.", 1976 (type)

"Zigongosaurus" (meaning "Zigong lizard") is a genus of sauropod dinosaur from the Middle Jurassic-Late Jurassic-age Shaximiao Formation of Zigong, Sichuan, China. Because of incomplete knowledge of Jurassic Chinese sauropods, it has been hard to interpret, with some sources assigning it to "Omeisaurus", some to "Mamenchisaurus", and some to its own genus.

History and taxonomy

The genus was based on CV 00261, a specimen including a partial mandible, maxilla, and basioccipital (a bone from the braincase region). Additional bones from all areas of the skeleton, belonging to multiple individuals, were also described and assigned to the new genus. The authors thought it resembled "Omeisaurus", but was distinct based on vertebral details.cite journal |last=Hou |first=L.-h. |coauthors=S.-w. Zhou; and S.-c. Chao |year=1976 |title=New discovery of sauropod dinosaurs from Sichuan |journal=Vertebrata PalAsiatica |volume=14 |issue=3 |pages=160–165 |language=Chinese ] Early accounts in the popular press suggested it was a brachiosaurid.cite book |last=Glut |first=Donald F. |title=The New Dinosaur Dictionary |year=1982 |publisher=Citadel Press |location=Secaucus, NJ |isbn=0-8065-0782-9 |pages=p. 263 ] cite book |last=Lambert |first=David |coauthors=and the Diagram Group |title=A Field Guide to Dinosaurs |year=1983 |publisher=Avon Books |location=New York |isbn=0-380-83519-3 |pages=p. 119] cite book |last=Norman |first=David. B. |authorlink=David B. Norman |title=The Illustrated Encyclopedia of Dinosaurs: An Original and Compelling Insight into Life in the Dinosaur Kingdom |chapter=Camarasaurids & Brachiosaurids |year=1985 |publisher=Crescent Books |location=New York |pages=86-91 |isbn=0-517-468905 ]

Chinese sauropod taxonomy became increasingly convoluted in the 1980s. In 1983, Dong, Zhou, and Zhang named a species "Omeisaurus fuxiensis", which they based on different material than "Zigongosaurus fuxiensis", but then suggested that the two were the same animal.cite journal |last=Zhiming |first=Dong |authorlink=Dong Zhiming |coauthors=S. Zhou; and H. Zhang |year=1983 |title=Dinosaurs from the Jurassic of Sichuan |journal=Palaeontologica Sinica, New Series C |volume=162 |issue=33 |pages=1–136 |language=Chinese] Following this, the genus was thought to belong to "Omeisaurus",cite book |last=Lambert |first=David |coauthors=and the Diagram Group |title=The Dinosaur Data Book |year=1990 |publisher=Avon Books |location=New York |isbn=0-380-75896-3 |pages=p. 105] possibly as a synonym of "O. junghsiensis".cite book |last=McIntosh |first=Jack S. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka. (eds.)|title=The Dinosauria |year=1990 |publisher=University of California Press |location=Berkeley |isbn=0-520-06727-4 |pages=345-401 |chapter=Sauropoda] In the mid-1990s, opinion shifted, and the genus was instead assigned, by Zhang and Chen, to "Mamenchisaurus". They noted that it came from a stratigraphic level between the usual "Omeisaurus" and "Mamenchisaurus" beds in age, but more closely resembled "Mamenchisaurus". In particular, the neural spines of the vertebrae (the part of the vertebra that sticks up, over the passage for the spinal cord) in both genera have distinctive weak bifurcation, or splitting, that is not found in "Omeisaurus". The authors renamed it "Mamenchisaurus fuxiensis".cite book |last=Zhang |first=Y. |coauthors=W. Chen |year=1996 |chapter=Preliminary research on the classification of sauropods from Sichuan Basin, China |editor=Morales, M. (ed.)|title=The Continental Jurassic |series=Museum of Northern Arizona Bulletin, 60 |publisher=Museum of Northern Arizona |pages=97-107 ] This assignment was followed provisionally in the most recent major review of sauropods,cite book |last=Upchurch|first=Paul |coauthors=Barrett, Paul M., and Dodson, Peter. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka. (eds.)|title=The Dinosauria |edition=2nd |year= 2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=259-322 |chapter=Sauropoda] but at least one author (Valérie Martin-Rolland) has found it to be a distinct genus.cite journal |last=Martin-Rolland |first=Valérie |year=1999 |title=Les sauropodes chinois |journal=Revue Paléobiologie, Genève |volume=18 |issue=1 |pages=287–315 |language=French ]

Paleobiology

Whichever genus it turns out to be, as a mamenchisaur- or omeisaur-like sauropod it would have been a large, quadrupedal herbivore with a long neck. It is regarded as a medium- to large-sized sauropod, with a length of around 15 meters (50 feet).cite book|title=The Dinosaur Society Dinosaur Encyclopedia|year=1993|chapter="Omeisaurus"|author=Lessem, D., and Glut, D.F.|pages=329-330|publisher=Random House, Inc.|id=ISBN 0-679-41770-2]

References