Ruyangosaurus

Ruyangosaurus (Ruyang County lizard) is a genus of titanosauriform sauropod dinosaur recovered from the Early Cretaceous Haoling Formation of China. The type species is R. giganteus, described in 2009 by Lü Junchang et al. Along with Huanghetitan and Daxiatitan, Ruyangosaurus is among the largest dinosaurs discovered in Cretaceous Asia. The describers of Ruyangosaurus assigned it to Andesauridae. However, Andesauridae is not monophyletic and, as such, is no longer used. The most comprehensive phylogenetic dataset to include Ruyangosaurus finds it to be in a polytomy with Andesaurus and other basal titanosaurs and near-titanosaur somphospondyls, supporting the original description's assertion of phylogenetic proximity of it and Andesaurus, though not the precise taxonomic assignment. However, not all phylogenetic analyses have supported its position as a somphospondyl. A smaller phylogenetic dataset found Ruyangosaurus to be a non-titanosauriform macronarian based on additional material from the type locality. Ruyangosaurus shared its habitat with Xianshanosaurus, 'Huanghetitan' ruyangensis, Yunmenglong, Luoyanggia, and Zhongyuansaurus. The type horizon of Ruyangosaurus was originally described as being of 'early Late Cretaceous' age, but recent work has assigned it an Aptian-Albian Age based on fieldwork and analysis of invertebrate and microfossil assemblages.