කාලික පරාසය: Quaternary–Recent
|Aepyornis maximus skeleton and egg|
A. Newton, 1884
|2 genera, 7 species|
The elephant birds, which were giant ratites native to Madagascar, have been extinct since at least the 17th century. Étienne de Flacourt, a French governor of Madagascar in the 1640s and 1650s, recorded frequent sightings of elephant birds. Also the famous explorer and traveler Marco Polo mentions very large birds in his accounts of his journeys to the East during the 12th-13th centuries. These earlier accounts are today believed to describe elephant birds.Aepyornis was the world's largest bird, believed to have been over 3 metres (10 ft) tall and weighing close to 400 kg (880 lb). Remains of Aepyornis adults and eggs have been found; in some cases the eggs have a circumference of over 1 metre (3 ft) and a length up to 34 centimetres (13 in). The egg volume is about 160 times greater than a chicken egg.
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 treating them all in just one species, A. maximus. Up to three species are also generally included in Mullerornis.
- Aepyornis gracilis (Monnier, 1913)
- Aepyornis hildebrandti (Burckhardt, 1893)
- Aepyornis maximus (Hilaire, 1851)
- Aepyornis modestus (Milne-Edwards & Grandidier, 1869)
- Aepyornis ingens (Milne-Edwards & Grandidier, 1894)
- Aepyornis titan (Andrews, 1894)
- Aepyornis medius (Milne-Edwards & Grandidier, 1866)
- Aepyornis grandidieri (Rowley, 1867)
- Aepyornis cursor (Milne-Edwards & Grandidier, 1894)
- Aepyornis lentus (Milne-Edwards & Grandidier, 1894)
- Mullerornis betsilei (Milne-Edwards & Grandidier, 1894)
- Mullerornis agilis (Milne-Edwards & Grandidier, 1894)
- Mullerornis rudis (Milne-Edwards & Grandidier, 1894)
- Flacourtia rudis (Andrews, 1894)
Because there is no rainforest fossil record in Madagascar, it is not known for certain if there were species adapted to dense forest dwelling, like the cassowary in ඕස්ට්රේලියාව and New Guinea today. However, some rainforest fruits with thick, highly sculptured endocarps, such as that of the currently undispersed and highly threatened forest coconut palm Voanioala gerardii, may have been adapted for passage through ratite guts, and the fruit of some palm species are indeed dark bluish purple (e.g. Ravenea louvelii and Satranala decussilvae), just like many cassowary-dispersed fruits.
Like the cassowary, ostrich, rhea, emu and kiwi, Mullerornis and Aepyornis were ratites; they could not fly, and their 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. However, subfossil Aepyornis fragments have not yet been successfully sequenced for mitochondrial DNA. Some DNA has been extracted.
Supposed remains of "aepyornithid" eggs found on the eastern Canary Islands represent a major biogeographical enigma. These islands were probably not connected to mainland Africa when elephant birds were alive. During episodes of very low sea levels, there may have been a land bridge, and at least for some time, there probably was an archipelago between Fuerteventura/Lanzarote and the African coast. This might have enabled flightless birds to cross over to these islands. Still, there is no indication that elephant birds evolved outside Madagascar, and today, the Canary Island eggshells are considered to belong to extinct North African birds that may or may not have been ratites (Eremopezus/Psammornis), or even Pelagornithidae, prehistoric seabirds of immense size[තහවුරු කරන්න].
It is widely believed that the extinction of Aepyornis was a result of human activity. The birds were initially widespread, occurring from the northern to the southern tip of Madagascar. One theory states that humans hunted the elephant birds to extinction in a very short time for such a large landmass (the blitzkrieg hypothesis). There is indeed evidence that they were killed. Their eggs may have been particularly 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.
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).
An alternative theory is that the extinction was a secondary effect of human impact resulting from 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.).
English name[සංස්කරණය කරන්න]
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.
Malagasy name[සංස්කරණය කරන්න]
The ancient Malagasy name for the bird is Vorompatra, meaning "bird of the Ampatres". The Ampatres are today known as the Androy region of southern Madagascar. Indeed, Étienne de Flacourt wrote (1658), "vouropatra - a large bird which haunts the Ampatres and lays eggs like the ostriches; so that the people of these places may not take it, it seeks the most lonely places".
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 the skeleton of the unborn bird. The Denver Museum of Nature and Science (Denver, Colorado) holds two intact eggs, one of which is currently on display. Another giant Aepyornis egg is on display at the Harvard Museum of Natural History in Cambridge, MA. A cast of the egg is preserved at the Grant Museum of Zoology at London University.
David Attenborough owns an almost complete eggshell, dating from 6-700 CE, which he pieced together from fragments that were given to him while making his 1961 BBC series Zoo Quest to Madagascar. In March 2011, the BBC aired the 60 min. documentary Attenborough and the Giant Egg, presented by Attenborough, about his personal scientific quest to discover the secrets of the elephant bird and its egg.
There is also an intact specimen of an elephant bird's egg (contrasted with the eggs from other bird species, including a hummingbird's) on display at the Delaware Museum of Natural History, just outside Wilmington, Delaware, USA, and another in the Natural History Museum, London, England.
The Melbourne Museum in ඕස්ට්රේලියාව has two Aepyornis eggs. The first was acquired for 100 pounds by Professor Frederick McCoy in June 1862, and is an intact example. In 1950 it was subjected to radiological examination, which revealed no traces of embryonic material. A second, side-blown Aepyornis egg was acquired at a later date.
In art and literature[සංස්කරණය කරන්න]
- The Rukh is known from Sindbad the Sailor's encounter with one in "One Thousand and One Nights". Some scholars think the Roc is a distorted account of the Aepyornis. Historical evidence for this can be found in Megiser (1623).
- H.G. Wells wrote a short story entitled "Aepyornis Island" (1894) about the bird. It was first collected in The Stolen Bacillus and Other Incidents (1895).
- Wildlife artist Walton Ford created a painting called "Madagascar" about the Elephant Bird in 2002.
See also[සංස්කරණය කරන්න]
- Island gigantism
- Late Quaternary prehistoric birds
- New World Pleistocene extinctions
- Pleistocene megafauna
- Brands, S. (2008)
- BBC Two Presents (2011)
- Davies, S. J. J. F. (2003)
- Mlíkovsky, J. (2003)
- Hawkins, A. F. A. & Goodman, S. M. (2003)
- Brodkorb, P. (1963)
- Brands (a), S. (2008)
- LePage, D. (2008)
- Dransfield, J. & Beentje, H. (1995)
- Yoder, A. D. & Nowak, M. D. (2006)
- van Tuinen, M. et al. (1998)
- Hay, W. W., et al. (1999)
- Cooper, A., et al. (2001)
- International Darwin Bicentennial Symposium Ancient DNA
- Extinct giant bird DNA recovered from fossil eggs
- Sauer and Rothe, 1972
- Pearson and Godden (2002)
- Goodman, S. M. & Rakotozafy, L. M. A. (1997)
- Goodman, S. M. (1994)
- BBC News
- Attenborough and the Giant Egg. BBC. 2011-03-02. Retrieved on 2011-07-24.
- R.T.M. Pescott, 'Collections of a Century: The History of the First Hundred Years of the National Museum of Victoria, National Museum of Victoria, 1954, p.47.
- BBC News (2009-03-25). One minute world news. Day in Pictures (BBC News). සම්ප්රවේශය Mar 26 2009. Check date values in:
- BBC-2 Presents: Attenborough and the Giant Egg. Presenter: David Attenborough; Director: Sally Thomson; Producer: Sally Thomson; Executive Producer: Michael Gunton. BBC. BBC Two. March 2, 2011.
- Brands, Sheila J. (1989). The Taxonomicon : Taxon: Order Aepyornithiformes. Zwaag, Netherlands: Universal Taxonomic Services. සම්ප්රවේශය 21 Jan 2010.
- Brands(a), Sheila (Aug 14 2008). Systema Naturae 2000 / Classification, Genus Aepyornis. Project: The Taxonomicon. සම්ප්රවේශය Feb 04 2009. Check date values in:
- Brodkorb, Pierce (1963). "Catalogue of Fossil Birds Part 1 (Archaeopterygiformes through Ardeiformes)" (PDF). Bulletin of the Florida State Museum, Biological Sciences (Gainesville, FL: University of Florida) 7 (4): 179–293. http://ufdc.ufl.edu/UF00001514/00001/98j.
- Cooper, A.; Lalueza-Fox, C.; Anderson, S.; Rambaut, A.; Austin, J.; Ward, R. (2001-02-08). "Complete Mitochondrial Genome Sequences of Two Extinct Moas Clarify Ratite Evolution". Nature 409 (6821): 704–707. doi:10.1038/35055536. PMID 11217857.
- Davies, S. J. J. F. (2003). "Elephant birds". in Hutchins, Michael. Grzimek's Animal Life Encyclopedia. 8 Birds I Tinamous and Ratites to Hoatzins (2 ed.). Farmington Hills, MI: Gale Group. pp. 103–104. ISBN 0 7876 5784 0.
- Dransfield, John; Beentje, Henk (1995) The Palms of Madagascar Kew, Victoria, ඕස්ට්රේලියාව: Royal Botanic Gardens ISBN 0 947643 82 6
- Flacourt, Etienne de.; Allibert, Claude (2007) (Frenchයෙන්) Histoire de la grande île de Madagascar Paris, FR: Karthala ISBN 2845865821
- Goodman, Steven M. (1994). "Description of a new species of subfossil eagle from Madagascar: Stephanoaetus (Aves: Falconiformes) from the deposits of Ampasambazimba". Proceedings of the Biological Society of Washington (107): 421–428.
- Goodman, S. M.; Patterson, B. D., eds. (1997) "Subfossil birds from coastal sites in western and southwestern Madagascar" Natural Change and Human Impact in Madagascar Washington, DC: Smithsonian Institution Press pp. 257–279 ISBN 1560986832
- Hawkins, A. F. A.; Goodman, S. M. (2003) Goodman, S. M.; Benstead, J. P. eds. The Natural History of Madagascar University of Chicago Press pp. 1026–1029 ISBN 0226303071
- Hay, W. W.; DeConto, R. M.; Wold, C. N.; Wilson, K. M.; Voigt, S. (1999) "Alternative global Cretaceous paleogeography" මෙම කෘතිය තුල: Barrera, E.; Johnson, C. C. Evolution of the Cretaceous Ocean Climate System Boulder, CO: Geological Society of America pp. 1–47 ISBN 0813723329
- LePage, Dennis (2008). Aepyornithidae. Avibase, the World Bird Database. සම්ප්රවේශය 04 Feb 2009. Check date values in:
- MacPhee, R. D. E.; Marx, P. A. (1997) "The 40,000 year plague: humans, hyperdisease, and first-contact extinctions" මෙම කෘතිය තුල: Goodman, S. M.; Patterson, B. D. Natural Change and Human Impact in Madagascar Washington DC: Smithsonian Institution Press pp. 169–217
- Megiser, H. (1623) Warhafftige ... so wol Historische als Chorographische Beschreibung der ... Insul Madagascar, sonsten S. Laurentii genandt (etc.) Leipzig: Groß
- Mlíkovsky, J. (2003). "Eggs of extinct aepyornithids (Aves: Aepyornithidae) of Madagascar: size and taxonomic identity". Sylvia 39: 133–138.
- Pearson, Mike Parker; Godden, K. (2002) In search of the Red Slave: Shipwreck and Captivity in Madagascar Stroud, Gloucestershire: The History Press ISBN 0750929383
- Sauer, E. G. Franz; Rothe, Peter (1972-04-07). "Ratite Eggshells from Lanzarote, Canary Islands". Science (AAAS) 176 (4030): 43–45. doi:10.1126/science.176.4030.43. http://www.sciencemag.org/content/176/4030/43.abstract. ප්රතිෂ්ඨාපනය 2011-03-05.
- van Tuinen, Marcel; Sibley, Charles G.; Hedges, S. Blair (1998). "Phylogeny and Biogeography of Ratite Birds Inferred from DNA Sequences of the Mitochondrial Ribosomal Genes" (PDF). Molecular Biology and Evolution 15 (4): 370–376. http://mbe.oxfordjournals.org/content/15/4/370.full.pdf.
- Yoder, Anne D.; Nowak, Michael D. (2006). "Has Vicariance or Dispersal Been the Predominant Biogeographic Force in Madagascar? Only Time Will Tell". Annual Review of Ecology, Evolution, and Systematics 37: 405–431. doi:10.1146/annurev.ecolsys.37.091305.110239.