A new titanosaurian sauropod, Gandititan cavocaudatus gen. et sp. nov., from the Late Cretaceous of southern China

Large quadrupedal sauropod dinosaurs of the group Titanosauria were globally distributed in the Late Cretaceous. Many titanosaurian species have been discovered in eastern Asia, but most of them are controversial and represented by poorly preserved remains. Here, we describe a new titanosaur, Gandititan cavocaudatus gen. et sp. nov., based on a partial skeleton recovered from the lower Upper Cretaceous of Ganxian County, Ganzhou City, southern China, and comprising six articulated cervical vertebrae, two partial dorsal vertebrae, and a complete sacrum preserved in articulation with the first 17 caudal vertebrae and part of the right pelvis. Gandititan can be diagnosed on the basis of the following autapomorphies: long and narrow fossae present on the dorsal and ventral parts of the lateral surfaces of the cervical centra, sacral neural spines forming a dorsal platform with wave-shaped lateral margins, anteriormost six caudal vertebrae with bifurcated neural spines, the presence of prominent triangular flanges on the transverse processes of the anteriormost caudal vertebrae, a pair of slit-like foramina present on the ventral surface of each anterior caudal centrum, lateral surfaces of neural arches strongly excavated, additional spinoprezygapophyseal laminae present, and a prominent lamina extending horizontally between the bases of the pre- and postzygapophyses in some anterior caudal vertebrae. An expanded phylogenetic analysis places Gandititan as the sister taxon to Abdarainurus, within a clade of non-lithostrotian titanosaurs that also includes the Chinese titanosaurs Dongyangosaurus, Baotianmansaurus and Huabeisaurus, as well as the Argentine titanosaur Andesaurus. Such results imply the possible existence of a previously unrecognized group of titanosaurs in eastern Asia, and potential dispersal of titanosaurs between Asia and South America during the mid-Cretaceous.