Abstract
The Early Jurassic ornithischian dinosaurs in Laurasia are dominated by armored dinosaurs, with other early ornithischian groups being rare. Here, a new taxon, Archaeocursor asiaticus gen. et sp. nov., is reported from the Lower Jurassic of southwestern China. Phylogenetic analysis places Archaeocursor asiaticus as the earliest-diverging ornithischian dinosaur yet discovered in Asia, albeit with weak support. Osteohistological analysis of the femoral cross-section suggests that Archaeocursor asiaticus was a young adult at the time of death, indicating a small body size of approximately 1 m in body length. This discovery extends the known presence of ornithischian dinosaurs in East Asia to the Pliensbachian or even late Sinemurian stages. Additionally, it points to an earlier dispersal event of Early Jurassic ornithischian dinosaurs from Gondwana to Laurasia, including East Asia, which appears to be independent of, and possibly earlier than, the dispersal of armored dinosaurs.