Mamenchisauridae, Young and Zhao, 1972

Suteethorn, Suravech, Loeuff, Jean Le, Buffetaut, Eric, Suteethorn, Varavudh & Wongko, Kamonrak, 2013, First evidence of a mamenchisaurid dinosaur from the Upper Jurassic-Lower Cretaceous Phu Kradung Formation of Thailand, Acta Palaeontologica Polonica 58 (3), pp. 459-469 : 467

Mamenchisauridae indet. B

Material.— SDRC KB1−1 , a dorsal vertebra from Khlong Thorn District , Krabi, Khlong Min Formation, southern Thailand .

Remarks.—A sauropod vertebra from the Upper Jurassic Khlong Min Formation of southern Thailand was described by Buffetaut et al. (2005). The shape of the centrum and the position of the parapophysis indicate a position midway through the dorsal vertebral series and its pneumatic camellate structure resembles that of the mamenchisaurids and Titanosauriformes ( Wedel 2003). Buffetaut et al. (2005) noted the difference between these groups using pleurocoel shape, the pleurocoels of Titanosauriformes tending to have a tapering, acute caudal margin. They considered the vertebra from southern Thailand as a mid−dorsal vertebra of a euhelopodid (sensu Upchurch 1995, 1998) on the basis of camellate structure and the shape of the pleurocoel. This vertebra can be excluded from the genus Euhelopus because of the lack of a “K”−lamina, an autapomorphic character of Euhelopus recognized by Wilson and Upchurch (2009). It resembles Mamenchisaurus and Omeisaurus in several respects and accordingly can be placed in the family Mamenchisauridae .