New evidence for the earliest ornithischian dinosaurs from Asia
Xi Yao,
Qi Zhao,
Tingcong Ren,
Guangbiao Wei,
Xing Xu
Affiliations
Xi Yao
Center for Vertebrate Evolutionary Biology, Yunnan University, Kunming 650091, China; Corresponding author
Qi Zhao
Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China
Tingcong Ren
Southeast Sichuan Geological Team, Chongqing Bureau of Geology and Minerals Exploration, Chongqing 400038, China
Guangbiao Wei
Chongqing Institute of Paleontology, Chongqing 401122, China; Corresponding author
Xing Xu
Center for Vertebrate Evolutionary Biology, Yunnan University, Kunming 650091, China; Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China
Summary: 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.
