Sunday, January 9, 2011

"Lancangosaurus" - Zhao's nomina nuda part 4

As always, general references are in the first post of the series.

"Lancangosaurus" Zhao, 1980
"Lancanjiangosaurus" Zhao, 1983
"Lancangjiangosaurus cachuensis" Zhao, 1985
"Lancanjiangosaurus cachuensis" Chure and McIntosh, 1989
"Lancanjiangosaurus cahuensis" Glut, 1997
"Lancanjiangosaurus cashuensis" Martin-Rolland, 1999
"Lanchangjiangosaurus cachuensis" Fang, Zhang, Lu, Han, Zhao and Li, 2006
Etymology- The genus references the Lancang Jiang, the local name for the head of the Mekong River.  The species name refers to the Zaqu River, which is the upper reaches of the Mekong.
Middle Jurassic
Middle Dapuka Group, Dabuka, Qamdo County, Tibet, China
- (~15 m) specimen including skull, mandible, twelve teeth and limb elements
specimen (Fang et al., 2006)

Teeth of "Lancangosaurus" (after Zhao, 1985).

Comments- Though usually believed to be a preliminary name for Datousaurus (e.g. Olshevsky, 1991), "Lancangosaurus" was first reported by Zhao (1980) in relation to a Dapuka specimen, not the Xiashaximiao Datousaurus.  Listed characters are large skull, large spatulate teeth which decrease gradually in size posteriorly, a thick mandible and robust limbs.  Dong et al. (1983) believed the teeth were congeneric with those from the Wujiaba Quarry of the Shangshaximiao Formation, which they described as belonging to Omeisaurus junghsiensis and O. fuxiensis.  Zhao (1985) figures teeth in situ, though the photograph is unclear.  Note Olshevsky (1991) switched the authorship for the variants "Lancanjiangosaurus" and "Lancangjiangosaurus".  Glut (1997) incorrectly listed it as being Late Jurassic in age.  Fang et al. (2006) note additional material from lower in the same formation.  Given the etymology, either "Lancangosaurus" or "Lancangjiangosaurus" would be the most accurate names.
Relationships- "Lancanjiangosaurus" was stated by Zhao (1983) to be a bothrosauropodoid, in which he includes spatulate-toothed taxa like camarasaurids and brachiosaurids.  Zhao (1985) notes it is a sauropod similar to Cetiosaurus.  Chure and McIntosh (1989) listed it as a cetiosaurid, as does Olshevsky (1991) provisionally, while Lambert (1990) listed it as a brachiosaurid.  Glut (1997) merely referred it to Sauropoda incertae sedis.  Most recently, Fang et al. (2006) place it in Cetiosauridae.  The known characters are found in both basal eusauropods like Omeisaurus and camarasaurids, though the age, locality and Zhao's opinion all favor the former identification.  Whether Dong et al. are correct in placing it close to Omeisaurus is unknown, and for now I recommend keeping it as Eusauropoda incertae sedis.
References- Zhao, 1980. [Mesozoic vertebrate-bearing beds and stratigraphy of northern Xinjinag: Report of Paleontological Expedition to Xinjiang IV.] Memoirs of the Institute of Vertebrate Palaeontology and Palaeoanthropology, Academia Sinica A. 15, 1-119.
Dong, Zhou and Zhang, 1983. [Dinosaurs from the Jurassic of Sichuan]. Palaeontologica Sinica, New Series C. 162(23), 1-136 .
Martin-Rolland, 1999. Les sauropodes chinois [The Chinese sauropods]. Revue Paléobiologie, Genève. 18(1), 287-315.

1 comment:

  1. Go to Zhao named many genera but not finished the task. The list is long and left many in photography. Was there a reason or was it the way you work by this author?