Argentavis: Difference between revisions
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{{taxobox |
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| name = ''Argentavis magnificens'' |
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| image = Argentavis magnificens.JPG |
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| image_caption = Reconstruction of ''A. magnificens'' |
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| image_width = 250px |
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| fossil_range = [[Late Miocene]], {{fossil range|8|6}} |
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| regnum = [[Animal]]ia |
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| phylum = [[Chordate|Chordata]] |
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| classis = [[Bird|Aves]] |
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| ordo = [[Cathartiformes]] <small>(disputed)</small> |
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| familia = †[[Teratornithidae]] |
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| genus = [[extinction|†]]'''''Argentavis''''' |
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| genus_authority = [[Kenneth E. Campbell|Campbell]] & [[Eduardo P. Tonni|Tonni]], 1980 |
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| species = †'''''A. magnificens''''' |
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| binomial = ''Argentavis magnificens'' |
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| binomial_authority = Campbell & Tonni, 1980 |
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}} |
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'''''Argentavis magnificens''''' ("magnificent Argentine bird", or more literally "magnificent [[Argentina#Name and etymology|silver]] bird") is one of the largest flying birds ever known, possibly surpassed in wingspan only by the recently discovered ''[[Pelagornis sandersi]]''. ''A. magnificens'', sometimes called the giant [[teratorn]], is an [[extinction|extinct]] [[species]] known from three sites from the late [[Miocene]] of central and northwestern [[Argentina]], where a good sample of [[fossil]]s have been obtained.<ref>[http://news.bbc.co.uk/2/hi/science/nature/6262740.stm Ancient American bird was glider]. ''[[BBC]]'', 2007-JUL-02. Retrieved 2008-JAN-14</ref> |
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==Description== |
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The [[humerus]] (upper arm bone) of ''Argentavis'' is somewhat damaged. Even so, it allows a fairly accurate estimate of its length in life. ''Argentavis''{{'s}} humerus was only slightly shorter than an entire human arm.<ref name=c&t1983/> The species apparently had stout, strong legs and large feet which enabled it to walk with ease. The bill was large, rather slender, and had a hooked tip with a wide gape. |
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===Size=== |
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''Argentavis'' had an estimated wing span of {{convert|7|m|ft|abbr=on}}, a height of circa {{convert|1.5|m|ft|abbr=on}}, and a mass of approximately {{convert|72|kg|lb|abbr=on}}. |
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In 2014, another extinct species, ''[[Pelagornis sandersi]]'', was described as having a similar size (although only weighing 22 to 40 kg).<ref name=NG-Vergano>{{cite news|last1=Vergano|first1=Dan|title=Biggest Flying Seabird Had 21-Foot Wingspan, Scientists Say|url=http://news.nationalgeographic.com/news/2014/07/140707-bird-biggest-flight-ancient-wings-charleston-science/|accessdate=8 July 2014|publisher=National Geopraphic|date=8 July 2014}}</ref> For comparison, the living bird with the largest wingspan is the [[wandering albatross]], at {{convert|3.65|m|ft|abbr=on}}. Since ''A. magnificens'' is known to have been a land bird, another good point of comparison is the [[Andean condor]], one of the largest extant land birds, with a wingspan of up to {{convert|3.2|m|ft|abbr=on}} and weight of up to {{convert|15|kg|lb|abbr=on}}, and which is not too distantly related to ''Argentavis''. |
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The ability to fly is not a simple question of weight ratios, except in extreme cases. Size and structure of the wing must also be taken into account. As a rule of thumb, a [[wing loading]] of 25 kg/m<sup>2</sup> is considered the limit for avian flight.<ref name=Meunier/> |
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The ''heaviest'' extant flying birds are known to weigh up to {{convert|21|kg|lb|abbr=on}} (there are several contenders, among which are the European [[great bustard]] and the African [[kori bustard]]). A [[mute swan]], which may have personally lost the power of flight due to extreme weight, was found to have weighed {{convert|23|kg|lb|abbr=on}}.<ref name="Wood">{{cite book|last=Wood |first=Gerald |title=The Guinness Book of Animal Facts and Feats |year=1983 |isbn=978-0-85112-235-9}}</ref> The [[sarus crane]] is the tallest flying bird alive, at up to {{convert|1.8|m|ft|abbr=on}} tall, standing about as high as ''Argentavis'' due to its long legs and neck. |
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The largest known flying creatures are a group of [[pterosaur]]s named [[Azhdarchidae|azhdarchids]], extinct flying reptiles that existed during the age of the [[dinosaur]]s and died out at the end of the [[Cretaceous]]. Estimations of the wingspan of the largest species like ''[[Quetzalcoatlus]]'' and ''[[Hatzegopteryx]]'' exceed {{convert|10|m|ft|abbr=on}}, with less conservative estimates being {{convert|12|m|ft|abbr=on}} or more. Mass estimates for these azhdarchids are on the order of {{convert|200|–|250|kg|lb|abbr=on}}.<ref name=wittonweight2010>{{cite journal| last1 = Witton | first1 = M.P. | last2 = Habib | first2 = M.B. | year = 2010 | title = On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness | url = http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0013982 | journal = PLoS ONE | volume = 5 | issue = 11| page = e13982 | doi = 10.1371/journal.pone.0013982 | pmid=21085624 | pmc=2981443}}</ref> |
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Currently accepted estimates: |
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* [[Wingspan]]: approximately {{convert|7|m|ft|abbr=on}}<ref name="Chatterjee07">{{cite journal|title=The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina|volume=104|issue=30|pages=12398–12403|date=2007-07-24|journal=PNAS|doi=10.1073/pnas.0702040104|last1=Chatterjee|first1=S.|last2=Templin|first2=R. J.|last3=Campbell|first3=K. E.|pmid=17609382|pmc=1906724}}</ref> |
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* Wing area: {{convert|8.11|m2|ft2|abbr=on}}<ref name="Chatterjee07" /> |
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* [[Wing loading]]: 84.6 [[Pascal (unit)|N/m<sup>2</sup>]]<ref name="Chatterjee07" /> (1.77 lbs/ft<sup>2</sup>) |
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* Body Length: {{convert|1.26|m|ft|abbr=on}}<ref name="Chatterjee07" /> |
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* Height: {{convert|1.5|–|2|m|ft|abbr=on}}{{Citation needed|date=February 2012}} |
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* Mass: {{convert|70|–|72|kg|lb|abbr=on}}<ref name="Chatterjee07" /> |
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==Paleobiology== |
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===Life history=== |
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[[File:Argentavis.jpg|thumb|right|Illustration]] |
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Comparison with extant birds suggests it laid one or two eggs with a mass of somewhat over 1 kg (smaller than an [[ostrich]] egg) every two years. Climate considerations make it likely that the birds incubated over the winter, mates exchanging duties of incubating and procuring food every few days, and that the young were independent after some 16 months, but not fully mature until aged about a dozen years. Mortality must have been very low; to maintain a viable population less than about 2% of birds may have died each year. Of course, ''Argentavis'' suffered hardly any predation, and mortality was mainly from old age, accidents and disease.<ref name=Palmqvist/> |
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===Flight=== |
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From the size and structure of its wings it is inferred that ''A. magnificens'' flew mainly by soaring, using flapping flight only during short periods. It is probable that it used thermal currents as well. It has been estimated that the minimal velocity for the wing of ''A. magnificens'' is about 11 m/s or {{convert|40|km/h|mi/h}}.<ref name=Vizcaino/> Especially for takeoff, it would have depended on the wind, as although its legs were strong enough to provide it with a running or jumping start, the wings were simply too long to flap effectively until the bird was some height off the ground.<ref name=c&t1983/> However, skeletal evidence suggests that its breast muscles were not powerful enough for wing flapping for extended periods.<ref>Yong, Ed (2007-07-08) [http://notexactlyrocketscience.wordpress.com/2007/07/08/argentavis-the-largest-flying-bird-was-a-master-glider/ Argentavis, the largest flying bird, was a master glider]. notexactlyrocketscience.wordpress.com</ref> ''Argentavis'' may have used mountain slopes and headwinds to take off, and probably could manage to do so from even gently sloping terrain with little effort. It may have flown and lived much like the modern [[Andean condor]], scanning large areas of land from aloft for carrion. The climate of the Andean foothills in Argentina during the late Miocene was warmer and drier than today, which would have further aided the bird in staying aloft atop thermal updrafts. |
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===Feeding=== |
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''Argentavis''{{'}} [[territory (animal)|territories]] measured probably more than 500 km<sup>2</sup>, which the birds screened for food, possibly utilizing a generally north-south direction to avoid being slowed by adverse winds. This species seems less [[aerodynamic]]ally suited for [[predation]] than its relatives. It probably preferred to scavenge for carrion, and it is possible that it habitually chased [[metatheria]]n carnivores such as [[Thylacosmilidae]] from their kills. Unlike extant condors and vultures, the other species of teratorns generally had long, [[eagle]]-like beaks and are believed to have been active predators, being less ponderous than ''Argentavis''. When hunting actively, ''A. magnificens'' would probably have swooped from high above onto their prey, which they usually would have been able to grab, kill, and swallow without landing. Skull structure suggests that it ate most of its prey whole rather than tearing off pieces of flesh.<ref name=c&t1983/> |
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==References== |
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{{Reflist|2|refs= |
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<ref name=c&t1983>{{cite journal |last1=Campbell |first1=Kenneth E. Jr. |last2=Tonni |first2=E. P. |year=1983 |title=Size and locomotion in teratorns |journal=[[The Auk|Auk]] |volume=100 |issue=2 |pages=390–403 |url=http://sora.unm.edu/sites/default/files/journals/auk/v100n02/p0390-p0403.pdf}}</ref> |
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<ref name=Meunier>{{cite journal |last1=Meunier |first1=K. |year=1951 |title= Korrelation und Umkonstruktionen in den Größenbeziehungen zwischen Vogelflügel und Vogelkörper |trans_title=Correlation and restructuring in the size relationship between avian wing and avian body |language=German |journal=Biologia Generalis |volume=19 |pages=403–443}}</ref> |
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<ref name=Palmqvist>{{cite journal |last1=Palmqvist |first1=Paul |last2=Vizcaíno |first2=Sergio F. |year=2003 |title=Ecological and reproductive constraints of body size in the gigantic ''Argentavis magnificens'' (Aves, Theratornithidae) from the Miocene of Argentina |journal=Ameghiniana |volume=40 |issue=3 |pages=379–385 |url=http://webpersonal.uma.es/de/ppb/Argentavis.pdf}}</ref> |
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<ref name=Vizcaino>{{cite journal|last1=Vizcaíno |first1=Sergio F. |last2=Palmqvist |first2=Paul |last3=Fariña |first3=Richard A. |year=2000 |title=¿Hay un límite para el tamaño corporal en las aves voladoras? |trans_title=Is there a limit to body size in flying birds? |journal=Encuentros en la Biología |volume=64 |language=Spanish |url=http://www.ciencias.uma.es/publicaciones/encuentros/ENCUENTROS64/aves.html}}</ref> |
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}} |
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==Further reading== |
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*{{cite journal | last1 = Campbell | first1 = Kenneth E. Jr. | last2 = Tonni | first2 = E.P. | year = 1980 | title = A new genus of teratorn from the Huayquerian of Argentina (Aves: Teratornithidae) | url = | journal = Contributions in Science, Natural History Museum of Los Angeles County | volume = 330 | issue = | pages = 59–68 }} |
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*[[Peter Wellnhofer|Wellnhofer, Peter]] (1996): ''The Illustrated Encyclopedia of Pterosaurs''. Barnes and Noble Books, New York. ISBN 0-7607-0154-7 |
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==External links== |
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{{Portal|Paleontology}} |
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*[http://www.argentavis.net Argentavis information] Website about the Argentavis magnificens |
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*[http://news.bbc.co.uk/2/hi/science/nature/6262740.stm BBC News: Ancient American bird was glider] – BBC News article |
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*[http://www.telegraph.co.uk/science/science-news/3299302/How-the-dinosaur-bird-took-to-the-skies.html How the dinosaur bird took to the skies] – Telegraph.co.uk article |
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*[http://www.cosmosmagazine.com/node/1421 Secret of flight for world's largest bird revealed][Dead Link] – COSMOS Magazine article |
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*[http://notexactlyrocketscience.wordpress.com/2007/07/08/argentavis-the-largest-flying-bird-was-a-master-glider/ Argentavis, the largest flying bird, was a master glider] – Article from the blog ''Not Exactly Rocket Science'' |
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[[Category:Miocene birds]] |
[[Category:Miocene birds]] |
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