New discovery of Cretaceous dinosaur track fauna in Xichang basin, Sichuan Province

The dinosaur fossils haven't been recorded in Cretaceous Xiaoba Formation in Xichang basin, Sichuan Province. Hence, the dinosaur footprints provide crucial information for improving the understanding of the Cretaceous dinosaur assemblages. In April 2007, the authors discovered a new dinosaur footprint assemblage in Xiaoba Formation at Luogan Township, Xide County. The Luogan tracksite is poorly preserved, but it contains abundant theropod tracks with basic morphological features. In general, the small the-ropod tracks (8~13cm) are characterized by moderate mesaxony (0.5~0.6) and wide divarication angles between digits Ⅱ and Ⅳ (70°~100°), few of which developed metatarsal pads. The authors tentatively hold that the Luogan theropod assemblages are probably similar to Eubrontes and Grallator of Jiaguan Formation in Sichuan basin, which provides new evidence that these two areas had similar dinosaur faunae in Middle Cretaceous. This discovery is of great significance for paleoclimate, paleogeography and stratigraphic contrast in Xichang basin. Detailed classification of footprints needs further study.