All dinosaurs start off life small. That’s as true for today’s birds as the titans of the Mesozoic, and it may have been a critical part of what allowed ancient dinosaurs to surpass mammals in size. In order to hatch and grow into such stupendous shapes, though, the little egg-bound dinosaurs had to be nestled in a cozy little refuge. How did the biggest of the big care for their incubating little ones?

The classic image of a dinosaur on its nest is “Big Mamma.” Surrounded by elongated eggs, arms outstretched to protect them, the dinosaur was a model parent, even to the death. But this strategy wouldn’t have worked for huge, multi-ton dinosaurs, particularly