Largest organisms were related to the ostrich. They exceeded in height and . The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was "Dromornis stirtoni" of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae. The largest carnivorous bird was "Brontornis", an extinct flightless bird from South America which reached a weight of and a height of about . The tallest carnivorous bird was "Kelenken", which could reach 3 to 3.2 meters in height and 220 to 250 kilograms. The tallest bird ever was
Bird egg Bird egg Bird eggs are laid by the females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one (as in condors) to about 17 (the grey partridge). Clutch size may vary latitudinally within a species. Some birds lay eggs even when the eggs have not been fertilized; it is not uncommon for pet owners to find their lone bird nesting on a clutch of infertile eggs, which are sometimes called wind-eggs. The default color of vertebrate eggs is the white of the calcium carbonate from