It took paleontologists a long time to figure out how dinosaurs raised their babies. It was only in the 1920s that researchers figured out that dinosaurs actually laid eggs and did not give birth the way mammals did.
Different dinosaurs had different child rearing habits. Although we do not know everything about these habits, but there is sufficient evidence to show that most dinosaur eggs hatched young ones who could run and walk. A dinosaur would usually lay around 20 to 30 eggs but this number would vary depending on the different species. The reason for laying so many eggs boils down to the theory of survival of the fittest. Many of the babies were eaten by waiting predators the moment they were born and just a few would survive to reach adulthood.
For years paleontologists believed that dinosaurs actually laid their eggs and then forgot about them, leaving the young baby dinosaurs to fend for themselves. However, in the 1970s, a nesting ground of a duck-billed dinosaur named Maisaura was found in Montana by paleontologist Jack Horner. In this nesting ground, researchers found not just fossilized eggs but also fossils of newly hatched babies, young dinosaurs and adults.
Careful analysis of the fossils showed that the young Maisaura did not have fully developed leg muscles and therefore, were not capable of walking and running. In addition, the teeth of the baby dinosaurs showed wear and tear. This led paleontologists to conclude that the adult Maisauras actually brought back food to the nest so that young dinosaurs could eat until they were old enough to look after themselves. A similar site was found in China for Psittacosaurs.
However, it would be wrong to say that all herbivores took care of the newly hatched young ones. For example, based on certain evidence, scientists have concluded that sauropods did not take care of their young ones. A newborn Apatosaurus would have been around 12 inches long and could be easily crushed under the feet of its own mother. Therefore, the survival rate of an Apatosaurus would be higher if felt to fend on its own.
Scientists are still trying to find out more about the birthing and mothering habits of Tyrannosaurus Rex as hardly anything is known about its parenting habits.
