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
Largest prehistoric animals "Argentavis magnificens" which a wingspan of , and a body weight of . The largest-known waterfowl of all time belonged to the Dromornithidae (e.g. "Dromornis stirtoni"). The largest-known of Ciconiiformes was "Leptoptilos robustus", standing tall and weighing an estimated . The largest-known of the hesperornithines was "Canadaga arctica" at long. The largest-known diatryma was "Gastornis" tall, with large individuals up to tall. The largest-known teratorn and the largest flying bird ever was "Argentavis". The immense bird had a wingspan estimated up to and a weight up to . It was as high as an adult human when standing. The largest-known-ever