The earliest ceratopsian from the Tuchengzi Formation of Liaoning, China

ABSTRACT

A new ceratopsian specimen, Chaoyangsaurus youngi gen. et sp. nov., was collected from the Tuchengzi Formation (Middle or Late Jurassic) of Liaoning, China. Distinctive characteristics of the new species include quad-ratojugal overlapping posterior side of quadrate shaft; lack of a broad lateral surface of the quadrate shaft; convex posterior margin of the ventral portion of the quadrate; a ridge between the planar lateral and ventral surface of the angular. The discovery of Chaoyangsaurus youngi extends the record of ceratopsian from back in time from the Early Cretaceous into the Middle or Late Jurassic. Some characters of C. youngi may suggest a close relationship between Ceratopsia and Heterodontosauridae.