The eggs were found over 20 years ago, but only with modern technology were the infants inside discovered. What was found, shocked scientists to their very core. These babies had cartiligenous bones when they hatched, meaning they couldn't walk right away. Also, they had no teeth! No precocial reptiles that hatches has no teeth! Even baby crocs, which are cared for to an extent by their mother, have teeth!
This means that baby massospondylus were altricial, meaning they had to stay in the nest for a time after hatching and needed food brought to them, pre-chewed by their parents. When the babies were able to walk, they walked on all fours instead of on their hind legs like their parents. This is interesting, because massospondylus is a prosauropod, which is the ancestral group of sauropods, large long-necked dinosaurs that walked on all fours. The massospondylus hatchlings seemed to be a precursor to what was coming.