Aepyornis Maximus

''Aepyornis'' is a genus of aepyornithid, one of three genera of ratite birds endemic to Madagascar until their extinction sometime around 1000 CE. The species ''A. maximus'' weighed up to , and until recently was regarded as the largest known bird of all time. However, in 2018 the largest aepyornithid specimens, weighing up to , were moved to the related genus ''Vorombe''. Its closest living relative is the New Zealand kiwi.

Taxonomy

Brodkorb (1963) listed four species of ''Aepyornis'' as valid: ''A. hildebrandti'', ''A. gracilis'', ''A. medius'' and ''A. maximus''. However, Hume and Walters (2012) listed only one species, ''A. maximus''. Most recently, Hansford and Turvey (2018) recognized only ''A. hildebrandti'' and ''A. maximus''.
* ?''A. grandidieri'' Rowley 1867 nomen dubium
* ''Aepyornis hildebrandti'' Burckhardt, 1893 (Hildebrandt's elephant-bird)
** ''Aepyornis gracilis'' Monnier, 1913
** ''Aepyornis lentus'' Milne-Edwards & Grandidier, 1894
** ?''Aepyornis minimus''
** ?''Aepyornis mulleri'' Milne-Edwards & Grandidier, 1894
* ''Aepyornis maximus'' Hilaire, 1851 (Giant elephant-bird)
** ''Aepyornis cursor'' Milne-Edwards & Grandidier, 1894
** ?''Aepyornis intermedius''
** ''Aepyornis medius'' Milne-Edwards & Grandidier, 1866

The nominal species ''Aepyornis titan'' Andrews, 1894, was placed in the separate genus ''Vorombe'' by Hansford and Turvey (2018), with ''A. ingens'' a synonym of ''titan''. ''Aepyornis grandidieri'' Rowley, 1867 is an ootaxon known only from an eggshell fragment and hence a ''nomen dubium''. Hansford and Truvey (2018) also found ''Aepyornis modestus'' a senior synonym of all ''Mullerornis'' nominal species, making ''modestus'' the epithet of the ''Mullerornis'' type species.

Evolution

Like the cassowaries, ostriches, rheas, emu and kiwis, ''Aepyornis'' was a ratite; it could not fly, and its breast bone had no keel. Because Madagascar and Africa separated before the ratite lineage arose, ''Aepyornis'' has been thought to have dispersed and become flightless and gigantic ''in situ''. More recently, it has been deduced from DNA sequence comparisons that the closest living relatives of elephant birds are the New Zealand kiwis, indicating that the ancestors of elephant birds dispersed to Madagascar from Australasia.

Etymology

''Aepyornis maximus'' is commonly known as the 'elephant bird', a term that apparently originated from Marco Polo's account of the rukh in 1298, although he was apparently referring to an eagle-like bird strong enough to "seize an elephant with its talons". Sightings of eggs of elephant birds by early sailors (e.g. text on the Fra Mauro map of 1467–69, if not attributable to ostriches) could also have been erroneously attributed to a giant raptor from Madagascar. The legend of the roc could also have originated from sightings of such a giant subfossil eagle related to the African crowned eagle, which has been described in the genus '' Stephanoaetus'' from Madagascar, being large enough to carry off large primates; today, lemurs still retain a fear of aerial predators such as these. Another might be the perception of ratites retaining neotenic features and thus being mistaken for enormous chicks of a presumably more massive bird.

Description

''Aepyornis'', which was a giant, flightless ratite native to Madagascar, has probably been extinct since at least the 11th century (1000 CE). ''Aepyornis'' was one of the world's largest birds, believed to have been up to tall,Davies, S. J. J. F. (2003) with weights in the range for ''A. hildebrandti'' and for ''A. maximus''. Remains of ''Aepyornis'' adults and eggs have been found; in some cases the eggs have a circumference of over and a length up to .Mlíkovsky, J. (2003) The egg volume is about 160 times greater than a chicken egg.Hawkins, A. F. A. & Goodman, S. M. (2003)

Nocturnality

Endocasts of aepyornithid skulls have shown that these animals had poor eyesight and large olfactory bulbs, much like living kiwis. This has been interpreted as a sign that, like them, elephant birds were nocturnal.

Reproduction

Occasionally, the subfossilized eggs are found intact. The National Geographic Society in Washington holds a specimen of an ''Aepyornis'' egg which was given to Luis Marden in 1967. The specimen is intact and contains an embryonic skeleton of the unborn bird. Another giant ''Aepyornis'' egg is on display at the Harvard Museum of Natural History in Cambridge, MA. A cast of the ''Aepyornis'' egg is preserved at the Grant Museum of Zoology at the University of London. The BBC
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