The find of a herd of six "Psittacosaurus" individuals killed and buried by a volcanic mudflow indicates the presence of at least two age groups from two distinct clutches gathered together. This find has been taken as evidence for group fidelity and gregariousness extending beyond the nest; the earliest such evidence for any ceratopsian. Even very young psittacosaur teeth appear worn, indicating they chewed their own food and may have been precocial. Another juvenile-only cluster shows that specimens of different ages grouped together. These juveniles may have associated together as a close knit, mixed-age herd either for protection, to enhance their foraging, or as putative helpers at the parental nest. There is no evidence for parental care.