Dinosaurs expended little effort when it came to motherhood. Digging a shallow hole, they laid eggs in layers - one atop the other. Then the eggs were covered with a thin layer of soil. Following on such a monumental effort, the dinosaur would head out for its next meal.
Young dinosaurs, once they had worked their way out of their shells, needed to survive on their own. Many dinosaur eggs did not survive, most likely eaten by other dinosaurs who would discover the nest. Also, around this time (69.5 MYA), there were many small mammals with large brains compared to body size. This meant they would have had to employ their intelligence to survive, and accordingly would seek out caches of dinosaur eggs. Eggs from older rock layers would have thick shells whereas those found in younger layers have thin shells.
The fossilized dinosaur egg in this photograph is on exhibit at the Indodra Fossil and Dinosaur Park, Gandhinagar.
Scientists believe there were many millions of dinosaurs in existence during the Mesozoic Era circa 250 - 65 MYA. However, during the latter part of this era (145.5 to 65.95 MYA) an event occurred on planet Earth that resulted in the extinction of all land-based and avian dinosaurs. It is believed by many scientists that a series of monumental volcanic eruptions in what is present-day western India were the most likely causes. Evidence of volcanic activity may be seen in the gigantic Deccan Traps - lava beds centred near Mumbai.