Supplementary files of "<b>Discovery of large eusauropod dinosaur from the earliest Middle Jurassic of Chin</b><b>a</b>"

Sauropod dinosaurs were the largest terrestrial animals to have ever lived on Earth. However, in the initial evolutionary stages of sauropod gigantism, few fossils are known. In China, most non-sauropod sauropodomorphs from the Early Jurassic Lufeng Formation of southwestern China do not exceed 10 m in length, while all sauropods from the Middle Jurassic (Bajocian-Bathonian) Dashanpu quarry in the Sichuan Basin do exceed 10 m in length, with its largest member (<i>Omeisaurus</i>) around 16 t and 20 m long. Here, we report two large middle-posterior centra from dorsal vertebrae (the largest and most complete measures 142 mm in length; 201 mm in height, and 230 mm in width at its posterior articular surface) and other associated elements recovered from the earliest Middle Jurassic (Aalenican-earliest Bajocian) Xintiangou Formation in the Sichuan Basin of southwestern China. We perform a cladistic analysis and anatomical study to explore the affinities of the Xintiangou material and the early evolution of sauropod gigantism. The Xintiangou material is most likely an early-diverging eusauropod dinosaur. We recovered the specimen as being a diplodocoid sauropod belonging to the family Dicraeosauridae. This specimen was probably one of the first large-bodied sauropods in China, and may have been one of the largest in the world during the earliest Middle Jurassic. This discovery also provides further support for eusauropod-dominated assemblages that could have existed in China at the beginning of the Middle Jurassic.<br>