The genus was
based on CV 02501, 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. Early accounts in the popular press suggested it was a
brachiosaurid. 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. Following this, the genus was thought to belong to
Omeisaurus, possibly as a
synonym of
O. junghsiensis. 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. This assignment was followed provisionally in the most recent major review of sauropods, but at least one author (Valérie Martin-Rolland) has found it to be a distinct genus. ==Paleobiology==