An Important Ornithischian Tracksite in the Early Jurassic of the Shenmu Region, Shaanxi, China

Abstract:A large track site with multiple, well‐preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report ofMoyenisauripus‐like trackways from Asia, herein namedShenmuichnus youngteilhardorum. The tracks occur in a clastic fluvial sequence in the Fuxian Formation in Shenmu County, Shaanxi Province, which is in the same general region as the discovery site ofSinoichnites, the first dinosaur track reported from China. Based on size and morphology, it is likely thatSinoichnites, which is now lost, also represents an ornithischian. TheShenmuichnus youngteilhardorumtrackways show two modes of preservation: the first representing deeper tracks, with sediment rims, results inDeltapodus‐like tracks, with indistinct pes digit traces and sub‐circular manus traces, the second producesMoyenosauripus‐like tracks, with clear tridactyl and pentadactyl digit traces in the pes and manus respectively. Thus the Shenmu trackways play a key role in resolving globally significant ichnotaxonomic problems surrounding the nomenclature ofSinoichnites, Moyenosauripus, Deltapodusand other named (Ravatichnus) and unnamed trackways from Asia, Africa and Europe. In addition they shed important light on the paleogeographical and paleoecological distribution of quadrupedal ornithischians in the Early Mesozoic. The track site has been the focus of a major excavation to transfer the trackways from their original remote location to the new Shenmu Museum, in Shenmu City. Other tracksites in the area which revealAnomoepus, Grallatorand theDeltapodusmorphotype, together withShenmuichnusand plant fossil evidence, suggest an Early Jurassic age for the tracksite.