Dinosaurs hunted at night.

A new study has confirmed a belief held by some palaeontologists that some dinosaurs were active at night. Nocturnal animals need a maximum amount of light possible, so both their eyes and the eye openings tend to be larger than daytime animals. Researchers studied the fossilized eye sockets and scleroidal rings – a ring of bone that surrounds the iris of the eye in birds, lizards and dinosaurs. Of the 33 species studied most dinosaurs demonstrated some degree of nocturnal activity.

Most of the plant-eating dinosaurs were awake periodically. This means sporadically throughout the day or at dusk and dawn. All the predatory dinosaurs studied were either nocturnal or periodically hunting. Some Pterosaurs were also studied. They were mainly awake during the day, as was the case with all avian dinosaurs, although there was evidence of some species being nocturnal or awake periodically.