The discovery of fossilized dinosaur eggs, the nests that they were hatched in and even the baby dinosaurs inside the eggs, has given palaeontologists a great deal of information about how dinosaurs brought up their young. A 1979 find of fossil eggshells and babies of Maiasaura was particularly revealing. Taken together with study of nesting habits in modern birds and reptiles helps us to build up a picture of the dinosaurs’ parenting behaviour.

Using their feet, the mother dinosaurs gouged out hollows in the ground in which they laid their eggs. Then, using their teeth, they built up the soil around them and covered the eggs with a blanket of rotting vegetation to keep the eggs warm. Afterwards, they stood guard to keep predators away. The eggs were incubated by heat coming from rotting vegetation piled on top of them, rather than a parent sitting on the nest—although some smaller dinosaurs, for example, Citipati, did brood their eggs.

Eggs

The study of fossilized dinosaur eggs shows they had shells thin enough to allow oxygen to pass through, and for the baby to break out. The textured surface would have prevented the tiny pores in the shells from being blocked. Colours and patterns on the eggshells served to camouflage them from egg predators.

Babies

Fossils of some baby dinosaurs, Maiasaura for example, show that they were too weak to leave the nest. Their teeth were also partly worn, suggesting that adults brought food to them in their nest. Other fossil evidence, including fragments of trampled eggshell (from the mother and babies walking over them) and even the remains of regurgitated vegetation, confirm this.