Palaeontology: parental care in an ornithischian dinosaur.

Crocodilians and birds show extensive parental care of their young, but whether this behaviour evolved independently in these two groups of living archosaurs is unknown - in part because features of parenting among related fossil groups such as dinosaurs are unclear. A dramatic specimen of the small ornithischian dinosaur Psittacosaurus sp. (Dalian Natural History Museum D2156) from Liaoning in China reveals a single adult clustered with 34 juveniles within an area of 0.5 square metres, providing strong evidence for post-hatching parental care in Dinosauria.