Today’s reptiles take the tactic of burying their eggs underground – it protects them from predators, and helps preserve warmth. Some reptiles will also hang around their clutch to add additional protection.
However, most reptiles abandon their eggs, and leave them to develop, hatch, and live without interacting with them again. With the long incubation periods of dinosaurs now clearer, the question arose of whether dinosaurs hung around for the lengthy incubation period, or left them alone.
The birds with the very longest incubation periods, emperor penguins, take about two months to develop in the eggs. And they're certainly outliers: most bird breeds take between ten and thirty days to bust out of their shells.
Compared to modern-day reptiles, and especially ancient dinosaurs, that might as well be a blink of the eye in incubation terms.
Today's reptiles, on the other hand, tend to have an incubation period that lands between one and two months, which on average places them a lot closer to dinosaurs.
However, there are more details that lead researchers to believe dinosaurs aren't as closely related to reptiles than previously thought. In fact, the very way that modern reptiles interact with their developing eggs is different from how researchers believe dinosaurs acted.
Varricchio provides detail to us about the answer. There's evidence to suggest that unlike their modern-day cousins, some species of dinosaurs had quite a deal of parental instincts.
Several dinosaur species stayed with their eggs for the entire period of incubation, though it seems these species are usually those whose eggs took less time to hatch and were smaller in size.
Dinosaur parents that hung around would have provided additional protection from hungry predators. But for the eggs who took up to a year to hatch, like the Hypacrosaurus, it would have been quite the burden for dino moms and dads to remain in the same location.
If a predator knows you're always going to be in the same location for a long amount of time, even tiny dino brains might have figured out there are some tasty eggs nearby. Researchers have wondered if long incubation periods helped contribute to the extinction of some species.