The first turiasaurian sauropod (Dinosauria: Eusauropoda) from East Asia

The Middle Jurassic of China hosts a diverse dinosaur fauna dominated by mamenchisaurid sauropods, along with some early diverging eusauropod and neosauropod members. However, no transitional taxa have been confirmed in East Asia along the evolutionary path from mamenchisaurids to neosauropods. Here, we describe a new sauropod represented by six presacral vertebrae, Yantaloong lini gen. et sp. nov., recovered from the Middle Jurassic Zhanghe Formation of Yunnan Province, China. Most of our phylogenetic analyses recover Yantaloong within a non-traditional Turiasauria clade (including Lapparentosaurus, Jobaria, and Atlasaurus). Alternatively, some of our analyses also suggest that Yantaloong could be a non-neosauropod eusauropod outside the traditional Turiasauria or as a member of Neosauropoda, although these conditions are less favoured. Yantaloong shows a unique mixture of derived characters typically seen in derived dicraeosaurinaes and even in titanosaurs, along with plesiomorphic traits characteristic of basal eusauropods. Yantaloong provides a better understanding of the vertebral morphological diversity in sauropods, such as the pneumatization and the hyposphene–hypantrum complex, which further supports its phylogenetic position as a form transitional towards Neosauropoda. Yantaloong probably represents the first discovery of a turiasaurian sauropod in China and even in East Asia.