The first mamenchisaurid from the Upper Jurassic Dongxing Formation of Guangxi, southernmost China

A new mamenchisaurid sauropod dinosaur, Jingia dongxingensis gen. et sp. nov. from the Upper Jurassic of Southernmost China is reported here. The holotype consists of partly preserved dorsal, sacral, and caudal vertebrae, left and right ulna, and right femur. Anatomical comparison and phylogenetic analysis indicate that the new taxon belongs to Mamenchisauridae and bears a unique combination of characteristics, such as the ratio of the length of the neural spine to the narrowest width of the neural arch of the dorsal vertebra is about 4.4; sacral centrum is opisthocoelous with shallow depression exists on the lateral surface; centrum of anterior caudal vertebrae are amphicoelous, and the articular surfaces are transversely compressed; the anterolateral and anteromedial processes of the ulna are generally perpendicular in proximal view. Phylogenetically, Jingia dongxingensis gen. et sp. nov. is located at the later diverged position in Mamenchisauridae. This discovery increases the diversity of Mamenchisauridae and provides additional information to help understand the evolutionary radiation of eusauropods in China. It also indicates that this lineage is more competitive than penecontemporaneous neosauropods to dominate the Late Jurassic of East Asia.