Egg embryo is adequately developed it hatches, i.e. breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark, and was in size. Whale shark eggs typically hatch within the mother. At and up to , the ostrich egg is the largest egg of any living bird, though the extinct elephant bird and some dinosaurs laid larger eggs. The bee hummingbird produces the smallest known bird egg, which weighs half of a gram (around 0.02 oz). Some eggs laid
Largest prehistoric animals along with the closely related "Eotriceratops xerinsularis" both with estimated lengths of . Ojoceratops and several other ceratopsians rival them in size. The very largest-known ornithopods, like "Shantungosaurus" were as heavy as medium-sized sauropods at up to , and in length. The largest-known birds of all time might have been the elephant birds of Madagascar. Of almost the same size was the Australian "Dromornis stirtoni". Both were about tall. The elephant birds were up to and "Dromornis stirtoni" was up to in weight. The tallest bird ever was the giant moa ("Dinornis maximus") at tall. The largest-known flight-capable bird was