elephant bird, extinct, flightless bird of the family Aepyornithidae. Once native to the island of Madagascar, these gigantic birds may have survived until as late as 1649. Today, they are known only from bone specimens and a few well-preserved eggs. In appearance they are thought to have resembled monstrous ostriches, with the largest reaching heights of up to 10 ft (305 cm) and weighing perhaps as much as 1,000 lb (455 kg). Their eggs, the largest single cells in the animal kingdom, measured up to 13 in. (33 cm) in length and held a liquid content estimated at two gallons (7.5 liters). It is quite possible that the creation of the legendary roc of the Arabian Nights was based on discoveries of such eggs or even on distant memories of the elephant bird, for, if the roc legend did not originate in Madagascar, it has long been localized there by tradition. The largest of the elephant birds, Aepyornis maximus, was also the heaviest of all known birds. Elephant birds probably became extinct at the same time as the moas. Elephant birds are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Aepyornithiformes, family Aepyornithidae.