Social behaviour and mass mortality in the basal ceratopsian dinosaur psittacosaurus (early Cretaceous, People's Republic of China)

摘要: An exceptionally preserved herd of the ceratop- sian dinosaur Psittacosaurus was recovered from Lujiatun Beds Lower Cretaceous Yixian Formation, Liaoning Province, north-east China. This specimen provides earli- est direct evidence post-nestling gregarious behaviour in this important clade. The sediment which skeletons occur represents a lahar (volcanic mudflow), indi- cating that six individuals present were entombed simul- taneously during catastrophic mass mortality event. Reconstruction age profile shows it com- posed offspring at least two clutches, revealing group fidelity these dinosaurs extended beyond time spent together nest. demonstrates sociality appeared much earlier ceratopsian evolution than is gen- erally acknowledged and such preceded elaborate horns frills seen derived ceratopsids.