[D] Chungkingosaurus jiangbeiensis [Su] [sG] [T]
Dong, Zhou & Zhang, 1983
Jurassic Late Oxfordian
Ornithischia Thyreophora Stegosauria Stegosauridae
Shangshaximiao Formation, Chungking Group of Mai-eisni, Jiangbei,
near Chongqing Sichuan, China
Genus - Typespecies - Skull
Incomplete skeleton with skull, 3 fragmentary postcrania, adult
Chungkingosaurus jiangbeiensis is known from several medium-sized partial skeletons (length approximately 3-4 m) The hunerus is primitive in retaining a very proximal deltopectoral crest but derived in having very broad ends.
CV 207: ilio-sacral block and partial ischia found in Ouling Public Park in Chongqing;V 205: damaged sacral vertebrae, four caudal vertebrae, a right humerus and a pair of femora found in Huayibo, Chongqing; CV 208: ten posterior caudal vertebrae with associated chevrons and three pairs of dermal spines, found in Longshi, Hechuan, Sichuan. Dong, Zhou & Zhang (1983) and Dong (1990) suggested that each specimen may represent a different species of Chungkingosaurus, although the different specieswere never named due to the fragmentary nature of the material (Dong, Zhou & Zhang, 1983).
Current location of material
An ilio-sacral block, one dorsal vertebra, two caudal vertebrae, and three plates of CV 206, three caudal vertebrae and a tibia and fibula bearing the catalogue number CV 205 (although a tibia and fibula is not listed under the CV 205 material by Dong, Zhou & Zhang, 1983) and an ischium and pubis from CV 207 were in the collections of Chongqing Museum in September 2004. The location of the remaining material, including the cranial material belonging to the holotype and all of CV208, is currently unknown.
Differs from all other stegosaurs in that all of the sacral ribs are angled strongly posterolaterally. The anterior iliac processes do not diverge strongly from the parasagittal plane.
The location of all material from CV 205, referred to as ‘Chungkingosaurus sp. two’ by Dong, Zhou & Zhang (1983, p. 129), is unknown, except for a humerus, tibia and fibula (a tibia and fibula are not listed as part of CV 205 in the original description). No explanation for the assignment to a new species was given by Dong, Zhou & Zhang (1983) or Dong (1990). Tibiae, fibulae and humeri of stegosaurian dinosaurs are not diagnostic and do not differ a great deal between genera or species (see Galton, 1982b, 1985; Galton & Upchurch, 2004; pers. obs. 2004–2005). Since the rest of the material comprises caudal vertebrae, which are similarly undiagnostic, and is missing, CV 205 is here regarded as Stegosauria indet.
‘Chungkingosaurus sp. three’ was named for CV 208 by Dong, Zhou & Zhang (1983, p. 131) for material comprising ten posterior caudal vertebrae with three pairs of dermal spines. These elements were not represented among the original holotype material of Chungkingosaurus; comparisons cannot be drawn, and this material cannot therefore be referred to the latter genus. The location of this entire specimen is unknown so it is impossible to assess its validity independently.
Dong, Zhou & Zhang (1983) noted that the spines were laterally compressed with sharp anterior and posterior edges, a feature of the dermal armour that is common to many stegosaurs including Kentrosaurus and Dacentrurus. No other autapomorphies can be identified from the original description of Chungkingosaurus sp. three, and the fragmentary nature of the material precludes its referral to any other stegosaurian genus known from the fauna. CV 208 is therefore considered Stegosauria indet. (Maidment & Wei , 2006)