The first stegosaurian dinosaur from Gansu Province, China

Abstract

Stegosaurs are a minor but iconic clade of ornithischian dinosaurs, and along with their sister taxon ankylosaurs form the clade Eurypoda, the major radiation of Thyreophora (armoured dinosaurs). We here report some stegosaurian materials from the Lower Cretaceous Hekou Group of the Zhongpu area, Lanzhou-Minhe Basin, Gansu Province, China. Most of the morphology of the specimen is similar to Stegosaurus stenops and Stegosaurus homheni. However, its dorsal vertebrae have a higher neural arch and smaller neural canal than Stegosaurus stenops. The neural arches of the dorsal vertebrae of Stegosaurus homheni are deeply excavated dorsal to the neural canal in anterior view, which is not present in GSAU 201201. Because the material is fragmentary, we consider the new specimen as Stegosaurus sp. In phylogenetic analysis, it is also recovered as the sister taxon of Stegosaurus stenops. This is the first stegosaurian dinosaur from Gansu Province, which extends the geographical range of Stegosauria and enriches the Cretaceous stegosaurian record. The Ankylosaur Taohelong jinchengensis is also from the same area and same layer as this stegosaur, which is new evidence that they lived in the same ecosystems alongside each other.