For a long time, paleontologists assumed that dinosaurs laid hard-shelled eggs in nests that they often buried to protect them from predators. But more recent evidence shows that dinosaur eggs varied as much as the animals themselves, and some were soft-shelled -although those often don't keep their shape long enough to fossilize. Parenting strategies varied from dino to dino as well.
For example, consider the parrot-like dinosaurs called oviraptorids. Paleontologists have found the gorgeous skeletons preserved in a position where they seem to be sitting over nests of eggs. “It’s tempting to call this brooding, like living birds,” says San Diego Natural History Museum paleontologist Ashley Poust, “but we’re still unsure if that was part of their behavior.” Still, the details would indicate that the dinosaurs constructed their nests with care. Scientists know from previous finds that oviraptorids laid two eggs at a time in a clutch of 30 or more. “This means that the mother would have to stay with or at least return to the nest, lay her pair of eggs, arrange them carefully in the circle, and bury them appropriately every day for two weeks to a month,” Poust says.
Those eggs would have taken months to hatch. While experts are still searching for definitive evidence, parent dinosaurs may have sat with these nests until the hatchling babies pushed their way out of the shells. Also, Zelenitsky notes, researchers have found a large number of oviraptorosaur nests with adult dinosaur skeletons nearby. “These dinosaurs were completely obsessed with their eggs,” she says.
Each species had to balance the danger of staying with their nests against the odds of their young surviving without them, and developed different egg architecture, nests, and parenting strategies to maximize the chances of survival and successful reproduction, with varying results. Read how different dinosaurs dealth with their young, as far as we know now, at Smithsonian.
(Image credit: Emőke Dénes)