Elephant birds are members of the extinct
family Aepyornithidae. Elephant birds were
large to enormous flightless birds that once lived on the island of
Madagascar. They became
extinct, probably in the 17th or 18th century, for reasons that are unclear, although human activity is the suspected cause. Elephant birds comprised the
genera Mullerornis and
Aepyornis.
Aepyornis was among the heaviest of birds (the extinct
Dromornis stirtoni of Australia reached a similar weight). While they were in close geographical proximity to the
ostrich, elephant birds' closest living relatives are
kiwis, Elephant birds are actually part of the mid-Cenozoic Australian ratite radiation; their ancestors flew across the Indian Ocean well after
Gondwana broke apart. The existence of possible flying palaeognaths in the Miocene such as
Proapteryx further supports the view that ratites did not diversify in response to
vicariance. Gondwana broke apart in the Cretaceous and their phylogenetic tree does not match the process of
continental drift.