Tonganosaurus

Tonganosaurus is a genus of mamenchisaurid sauropod dinosaur, similar to Omeisaurus. It is known from one specimen consisting of twenty vertebrae, a front limb and pectoral girdle, and a complete hind limb with partial hip. It was discovered in the Yimen Formation, China. The horizon of the specimen and the age of the Yimen Formation is controversial. The formation has been divided into three levels, and Tonganosaurus appears to be of late Early Jurassic (Pliensbachian) in age. Tonganosaurus is the oldest known member of the mamenchisaurids, being almost 15 million years older than the next-oldest members of the group. It was first named by Li Kui, Yang Chun-Yan, Liu Jian, and Wang Zheng-Xin in 2010, and the type species is Tonganosaurus hei.