A New Titanosaurian Sauropod from the Upper Cretaceous of Jiangxi Province, Southern China

Jiangxititan ganzhouensis gen. et sp. nov. is a new titanosaurian sauropod recovered from the Upper Cretaceous (Maastrichtian) Nanxiong Formation of Jiangxi Province, southern China. It is characterised by: (1) posterior cervical and anterior dorsal centra strongly compressed dorsoventrally; (2) accessory horizontal laminae present within the anterior dorsal pleurocoels; (3) posterior cervical and anterior dorsal neural arches low; (4) posterior cervical and anterior dorsal neural spines deeply bifurcated and widely separated; (5) inverted ‘V’ lamina formed by the left and right medial spinoprezygapophyseal laminae present at the anterior margin of the bifid point in posteriormost cervical and anteriormost dorsal neural spines; (6) triangular fossa formed by the metapophysis, medial and lateral spinoprezygapophyseal laminae present at the anterior margins of the posteriormost cervical and anteriormost dorsal neural spines; (7) postzygapophyses in the posterior cervical vertebrae fan-shaped; (8) medial and lateral spinopostzygapophyseal laminae present in the anterior dorsal vertebrae; and (9) anterior dorsal rib short and gracil. Our phylogenetic analysis places Jiangxititan within the deeply-nested titanosauriform clade Lognkosauria and the sympatric Gannansaurus in a much earlier-diverging lineage. This new discovery thus demonstrates the presence of both early-diverging and late-diverging titanosauriform sauropods in the Late Cretaceous Ganzhou dinosaur fauna.