Aepyornis is an extinct genus also known as elephant birds.
Like the cassowary, ostrich, rhea, emu and kiwi, Aepyornis was a ratite; it could not fly, and its breast bones had no keel. Because Madagascar and Africa separated too long ago for the ratite lineage, Aepyornis had been thought to have dispersed and become flightless and gigantic in situ. A land bridge from elsewhere in Gondwana to Madagascar for the elephant bird-ostrich lineage was probably available around 85 million years ago.
Four species are usually accepted in the genus Aepyornis today; A. hildebrandti, A. gracilis, A. medius and A. maximus, but the validity of some is disputed, with numerous authors[weasel words] treating them all in just one species, A. maximus.
* Aepyornis gracilis Monnier, 1913
It is often believed that the extinction of the Aepyornis was an effect of human activity. However, the birds were probably not only elusive but widespread, occurring from the northern to the southern tip of Madagascar, yet their eggs were vulnerable. A recent archaeological study found remains of eggshells among the remains of human fires, suggesting that the eggs regularly provided meals for entire families, but it is not known if there were taboos ("fady") against the killing of adult birds, although there is indeed evidence that they were killed. Animals arriving with the human colonists, such as rats and dogs, may also have preyed upon the eggs of the ratite population and reduced their viability.
The exact time period when they died out is also not certain; tales of these giant birds may have persisted for centuries in folk memory. There is archaeological evidence of Aepyornis from a radiocarbon-dated bone at 1880 +/- 70 BP (= c. 120 AD) with signs of butchering, and on the basis of radiocarbon dating of shells, about 1000 BP (= c. 1000 AD). It is thought that Aepyornis is the Malagasy legendary extinct animal called the vorompatra, Malagasy for "marsh bird". vorom translates to bird. After many years of failed attempts, DNA molecules of Aepyornis eggs were successfully extracted by a group of international researchers and results were published in the Proceedings of the Royal Society B.
An alternative theory states that humans hunted the elephant birds to extinction in a very short time for such a large landmass (the blitzkrieg hypothesis) or is the possible secondary effect of human impact by possible transfer of hyperdiseases from human commensals such as chickens and guineafowl. The bones of these domesticated fowl have been found in subfossil sites in the island (MacPhee and Marx, 1997: 188), such as Ambolisatra (Madagascar), where Mullerornis sp. and Aepyornis maximus have been reported. Also reported by these authors, ratite remains have been found in W-SW Madagascar, at Belo-sur-Mer (A. medius, Mullerornis rudis), Bemafandry (M. agilis) and Lamboharana (Mullerornis sp.).
A third viable theory to explain the demise of the giant elephant birds, as apparently first pointed by Sir David Attenborough, is climate change, related to an increased drying of Madagascar during the Holocene (to which the impact of humans might have been additive). -
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.
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 London University, and has been adopted by Claudia, the niece of the author and illustrator Charlotte Cory. The BBC television personality David Attenborough owns an almost complete fossilized eggshell, which he pieced together from fragments he collected on a visit to Madagascar.
* Island gigantism
1. ^ a b c d e f g h i j k Brands, S. (2008)
* Attenborough, D. (1961). Zoo Quest to Madagascar. Lutterworth Press, London. 160 pp.
Source: Wikispecies, Wikipedia: All text is available under the terms of the GNU Free Documentation License