Labels:text | font | screenshot | document OCR: From the discoveries of dinosaur nests and eggs made so far, it appears that some species of dinosaurs spent time and energy looking after their young, while others did not. Maiasaura nests had eggshells that were broken into pieces, probably indicating that they had been trampled by young hatchlings constantly returning to the nest. Fossil hatchlings found in nests also had worn teeth, indicating that they had been fed inside the nest, or had left the nest for food and had then returned. All of this is strong evidence of Maiasaura showing parental care, by feeding and looking after young that were altricial (poorly developed on hatching). The nests of Troodon, on the other hand, contained opened but untrampled eggs, indicating that the young left the nest as soon as they hatched and did not return and trample the eggshells. This suggests that young Troodon dinosaurs may have been precocial (well-developed on hatching). FEEDING AND PROTECTION Dinosaurs that showed parental care, like Maiasaura, invested time in feeding and protecting their young. Females, and perhaps males, gathered food and brought it back to the nest. Because a nest was one of many in the nesting ground, the large number of adults living together may have acted as a deterrent to potential egg-stealers and predators. As the young Maiasaura grew larger and reached 2-3 m (61/2-10 ft) in length, they might have migrated with their parents to new feeding areas. Migration would have posed new threats to the young, because it is easy for predators to pick off stragglers from a herd. Therefore, Maiasaura parents perhaps stayed on the outside of the herd, while the vulnerable younger dinosaurs were protected within the herd from predators.
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