Editing Argentavis

{{short description|Extinct genus of very large birds}}
{{Speciesbox
| fossil_range = [[Miocene|Late Miocene]] ([[Huayquerian]])<br />~{{fossil range|9.0|6.8}}
| image = Argentavis magnificens.png
| image_caption = [[Life reconstruction]] of a grounded individual
| genus = Argentavis
| parent_authority = [[Kenneth E. Campbell|Campbell]] & [[Eduardo P. Tonni|Tonni]] 1980
| species = magnificens
| authority = Campbell & Tonni 1980
}}

'''''Argentavis''''' is an [[extinction|extinct]] [[genus]] of [[Teratornithidae|teratornithid]] known from three sites in the [[Epecuén Formation|Epecuén]] and [[Andalhualá Formation|Andalhualá]] Formations in central and northwestern [[Argentina]] dating to the [[Miocene|Late Miocene]] ([[Huayquerian]]). The type species, '''''A. magnificens''''', is sometimes called the '''giant teratorn'''. ''Argentavis'' was among the largest flying [[bird]]s to ever exist, holding the record for heaviest flying bird, although it was surpassed in wingspan after the 2014 description of ''[[Pelagornis sandersi]],'' which is estimated to have possessed wings some 20% longer than those of ''Argentavis''.<ref name=FWArgentavis>[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=39644 ''Argentavis''] at [[Fossilworks]].org</ref><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>

== Discovery and naming ==
In the 1970s while on an expedition by the [[La Plata Museum|Museo de La Plata]], paleontologists [[Rosendo Pascual]] and [[Eduardo Tonni]] unearthed a fragmentary skeleton consisting of a partial [[skull]], right [[coracoid]], left [[humerus]], portions of the left [[ulna]], left [[Radius (bone)|radius]], and left [[Metacarpal bones|metacarpals]], and [[Bone shaft|shafts]] of the right [[tibiotarsus]] and [[tarsometatarsus]].<ref name=":1">{{Cite journal |last1=Campbell |first1=Kenneth E. |last2=Tonni |first2=Eduardo P. |date=1980-09-15 |title=A new genus of teratorn from the Huayquerian of Argentina (Aves: Teratornithidae) |url=https://www.biodiversitylibrary.org/part/208145 |journal=Contributions in Science |volume=330 |pages=59–68 |doi=10.5962/p.208145}}</ref><ref name=":0">{{Cite journal |last1=Cenizo |first1=Marcos Martín |last2=Tambussi |first2=Claudia Patricia |last3=Montalvo |first3=Claudia Inés |date=2012 |title=Late Miocene continental birds from the Cerro Azul Formation in the Pampean region (central-southern Argentina) |url=http://www.tandfonline.com/doi/abs/10.1080/03115518.2011.582806 |journal=Alcheringa: An Australasian Journal of Palaeontology |language=en |volume=36 |issue=1 |pages=47–68 |doi=10.1080/03115518.2011.582806 |bibcode=2012Alch...36...47C |issn=0311-5518 |hdl=11336/54110 |hdl-access=free }}</ref> Later restudy of the specimen also found an incomplete [[Ungual|ungual phalanx]] with the skeleton.<ref name=":0" /> These fossils had been exposed in brown-red silt and clay sediments from the [[Cerro Azul Formation|Epecuén Formation]] in [[Salinas Grandes de Hidalgo]] in [[Atreuco Department|Atreucó]], [[Argentina]]. These outcrops derive from the [[Huayquerian]] stage of the [[Late Miocene|upper Miocene]] (9.0-6.8 mya). This specimen was deposited at the Museo de La Plata under catalogue number MLP 65-VII-29-49 and cast at the [[Natural History Museum of Los Angeles County|Los Angeles County Museum]].<ref name=":1" />

These fossils were described by paleontologists [[Kenneth Campbell Jr]]. and Eduardo Tonni in 1980, who named the new genus and species ''Argentavis magnificens'' with MLP 65-VII-29-49 as the [[holotype]] specimen. The generic name ''Argentavis'' is derived from the Latin root ''argentum'', “silver”, after the country of origin, and ''avis'', “bird”, while the specific name ''magnificens'', “magnificent”, refers to its size. In the description, ''Argentavis'' was classified as a member of [[Teratornithidae]] and was the first described from [[South America]].<ref name=":1" /> Since ''Argentavis''<nowiki/>' description, ''[[Taubatornis]]'' was named and a multitude of specimens described from the continent.<ref>{{Cite journal |last1=Cenizo |first1=Marcos |last2=Noriega |first2=Jorge I. |last3=Vezzosi |first3=RaúL I. |last4=Tassara |first4=Daniel |last5=Tomassini |first5=Rodrigo |date=2021-03-04 |title=First Pleistocene South American Teratornithidae (Aves): new insights into the late evolutionary history of teratorns |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2021.1927064 |journal=Journal of Vertebrate Paleontology |language=en |volume=41 |issue=2 |doi=10.1080/02724634.2021.1927064 |bibcode=2021JVPal..41E7064C |issn=0272-4634}}</ref><ref>Olson, S. L., & Alvarenga, H. (2002). A new genus of small teratorn from the Middle Tertiary of the Taubaté Basin, Brazil (Aves: Teratornithidae). ''Proceedings of the Biological Society of Washington''.</ref> Later in 1995, Campbell described three additional ''Argentavis'' specimens that had been discovered in other sites in Argentina. One, an ungual phalanx, was unearthed in an Epecuén Formation outcrops around 60&nbsp;km northeast of the holotype locality. Campbell assigned it to ''A. magnificens'' based on the development of grooves and [[tubercle]]s on the bone,<ref name=":3">Campbell Jr, K. E. (1995). Additional specimens of the giant teratorn, Argentavis magnificens, from Argentina (Aves: Teratornithidae). ''Courier Forschungsinstitut Senckenberg'', ''181'', 199-201.</ref> however due to the lack of overlap with the holotype and its robust morphology a 2011 article classified it as phorusrhacid.<ref name="Tambussi">{{Cite journal |last=Tambussi |first=Claudia |date=June 2011 |title=Palaeoenvironmental and faunal inferences based on the avian fossil record of Patagonia and Pampa: what works and what does not |journal=Biological Journal of the Linnean Society |volume=103 |issue=2 |pages=458–474 |hdl=11336/53447 |hdl-access=free |doi=10.1111/j.1095-8312.2011.01658.x |issn=0024-4066 |url=https://ri.conicet.gov.ar/bitstream/handle/11336/53447/CONICET_Digital_Nro.d8add167-e99f-4f07-8855-e0df7c5f4b5a_A.pdf?sequence=2&isAllowed=y }}</ref> Additionally, a fragmentary coracoid and the distal end of a tibiotarsus were collected from sediments of the Huayquerian-aged [[Andalhualá Formation]] in [[Valle de Santa María]] in [[Catamarca Province]], northwest Argentina.<ref name=":3" />

== Description ==
''Argentavis'' was a large bird, with the length of the skull and [[humerus]] (upper arm bone) measuring {{cvt|435|±|20|mm|in}} and {{cvt|570|±|10|mm|in}} respectively.<ref name=":1"/> Although the humerus of ''Argentavis'' is somewhat damaged, it allows a fairly accurate estimate of its length in life. ''Argentavis'' had stout, strong legs and large feet which indicate decent terrestrial capabilities.<ref name=c&t1983/>

[[File:62628-Argentavis-hegazti-erraldoia.svg|thumb|A comparison of ''Argentavis'' with (left to right) a human, a [[Palaeeudyptinae|giant Miocene penguin]], an [[emperor penguin]], an [[elephant bird]], an [[ostrich]] and an [[Andean condor]]. The estimated weight and wingspan of ''Argentavis'' as stated have since been reduced.]]

The initial description by Campbell and Tonni in 1980 tentatively estimated the wingspan of ''Argentavis'' between {{convert|6.5|to|7.5|m|ftin|0|abbr=on}} based on comparisons with ''Teratornis merriami''.<ref name=":1"/> The 1983 study by the same authors estimated the wingspan of ''Argentavis'' by scaling up the dimensions of the [[California condor]], with the highest estimate being {{convert|8.3|m|ftin|0|abbr=on}} and other estimates between {{convert|5.7|to|6.4|m|ftin|0|abbr=on}}.<ref name=c&t1983/> In their supplementary material of the 2024 paper, Gayford and colleagues considered the {{convert|8.3|m|ftin|0|abbr=on}} estimate to be an outlier.<ref>{{Cite journal |last1=Gayford |first1=Joel H. |last2=Engelman |first2=Russell K. |last3=Sternes |first3=Phillip C. |last4=Itano |first4=Wayne M. |last5=Bazzi |first5=Mohamad |last6=Collareta |first6=Alberto |last7=Salas-Gismondi |first7=Rodolfo |last8=Shimada |first8=Kenshu |date=September 2024 |title=Cautionary tales on the use of proxies to estimate body size and form of extinct animals |journal=Ecology and Evolution |language=en |volume=14 |issue=9 |pages=e70218 |doi=10.1002/ece3.70218 |pmid=39224151 |issn=2045-7758 |pmc=11368419|bibcode=2024EcoEv..1470218G }}</ref> In 2010, Mayr and Rubilar-Rogers estimated the wing skeleton length of ''Argentavis'' and ''[[Pelagornis|Pelagornis chilensis]]'' at {{convert|1.83|m|ftin|0|abbr=on}} and {{convert|2.1|m|ftin|0|abbr=on}} respectively, with ''P. chilensis'' having an estimated wingspan of {{convert|5.2|to|6.1|m|ftin|0|abbr=on}}, suggesting that ''Argentavis'' probably had a smaller wingspan unless it had much longer [[primary feather]]s.<ref>{{cite journal|author1=Mayr, Gerald  |author2=Rubilar-Rogers, David  |name-list-style=amp |doi=10.1080/02724634.2010.501465|title=Osteology of a new giant bony-toothed bird from the Miocene of Chile, with a revision of the taxonomy of Neogene Pelagornithidae|year=2010|journal=Journal of Vertebrate Paleontology|volume=30|issue=5|pages=1313–1330|bibcode=2010JVPal..30.1313M |s2cid=84476605 }}</ref> In his 2014 description of ''[[Pelagornis|Pelagornis sandersi]]'', Daniel Ksepka estimated the wingspan of ''P. sandersi'' at {{convert|6.06|to|7.38|m|ftin|0|abbr=on}}, exceeding that of ''Argentavis'' which he estimated at {{convert|5.09|to|5.57|m|ftin|0|abbr=on}} and {{convert|5.70|to|6.07|m|ftin|0|abbr=on}} based on regression analyses and comparisons with the California condor respectively.<ref name="Pelagornis">{{cite journal |last1=Ksepka |first1=Daniel T. |date=22 July 2014 |title=Flight performance of the largest volant bird |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=111 |issue=29 |pages=10624–10629 |bibcode=2014PNAS..11110624K |doi=10.1073/pnas.1320297111 |pmc=4115518 |pmid=25002475 |doi-access=free}}</ref><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/|archive-url=https://web.archive.org/web/20140708020453/http://news.nationalgeographic.com/news/2014/07/140707-bird-biggest-flight-ancient-wings-charleston-science/|url-status=dead|archive-date=July 8, 2014|access-date=8 July 2014|publisher=National Geographic|date=8 July 2014}}</ref> For comparison, the living bird with the largest wingspan is the [[wandering albatross]], reaching upwards of {{convert|3.5|m|ftin|0|abbr=on}}.<ref>{{Cite journal |last1=Sanchez |first1=Gerardo |last2=Salazar |first2=Ryan D. |last3=Hassanalian |first3=Mostafa |last4=Abdelkefi |first4=Abdessattar |date=8 January 2018 |title=Sizing and performance analysis of albatross-inspired tilt-wing unmanned air vehicle |url=https://arc.aiaa.org/doi/10.2514/6.2018-1445 |journal=Dynamic Loads, Response, and Stability of Aerospace Vehicles |series=AIAA SciTech Forum |language=en |publisher=American Institute of Aeronautics and Astronautics |doi=10.2514/6.2018-1445 |isbn=978-1-62410-532-6|url-access=subscription }}</ref><ref>{{Cite book |last=Barwell |first=Graham |url=https://books.google.com/books?id=I5AOBQAAQBAJ&q=Albatross+size |title=Albatross |date=15 October 2013 |publisher=Reaktion Books |isbn=978-1-78023-214-0 |pages=12–14 |language=en}}</ref>

The initial description by Campbell and Tonni in 1980 tentatively estimated the body mass of ''Argentavis'' at {{convert|120|kg|0|abbr=on}},<ref name=":1"/> while the 1983 paper by the same authors estimated its body mass at approximately {{convert|80|kg|0|abbr=on}}.<ref name=c&t1983/> Subsequent studies have suggested a lower body mass estimate between {{convert|70|and|72|kg|lb|0|abbr=on}}.<ref>{{cite journal|last1=Campbell, Jr.|first1=K. E.|last2=Marcus|first2=L.|year=1992|title=The relationship of hindlimb bone dimensions to body weight in birds|journal=Papers in Avian Paleontology Honoring Pierce Brodkorb|series=Science|issue=36|pages=395–412}}</ref><ref name="Chatterjee07">{{cite journal |last1=Chatterjee |first1=S. |last2=Templin |first2=R. J. |last3=Campbell |first3=K. E. |date=2007-07-24 |title=The aerodynamics of ''Argentavis'', the world's largest flying bird from the Miocene of Argentina |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=104 |issue=30 |pages=12398–12403 |bibcode=2007PNAS..10412398C |doi=10.1073/pnas.0702040104 |pmc=1906724 |pmid=17609382 |doi-access=free}}</ref><ref name="Alexander">{{cite journal |last1=Alexander |first1=David E. |date=24 July 2007 |title=Ancient Argentavis soars again |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=104 |issue=30 |pages=12233–12234 |bibcode=2007PNAS..10412233A |doi=10.1073/pnas.0705515104 |pmc=1941455 |pmid=17640902 |doi-access=free}}</ref> ''Argentavis'' still retains the title of the heaviest known flying bird by a considerable margin, with the aforementioned ''P. sandersi'' being estimated to have weighed no more than {{convert|21.9|to|40.1|kg|lb|abbr=on}}.<ref name="Pelagornis"/> Since ''A. magnificens'' is known to have lived in terrestrial environments, another good point of comparison is the [[Andean condor]], the largest extant flighted land bird both in average wingspan and weight, with the former spanning up to {{convert|3.3|m|ftin|0|abbr=on}} with an average of around {{convert|2.82|m|ftin|0|abbr=on}}, and the latter reaching a maximum of up to {{convert|15|kg|lb|abbr=on}}. [[New World vultures]] such as the condor are thought to be the closest living relatives to ''Argentavis'' and other teratorns. Average weights are much lower in both the wandering albatross and Andean condor than in ''Argentavis'', at approximately {{convert|8.5|kg|lb|abbr=on}} and {{convert|11.3|kg|lb|abbr=on}}, respectively.<ref name=CRC2>{{cite book |title=CRC Handbook of Avian Body Masses |edition=2nd |editor-first=John B. Jr. |editor-last=Dunning |publisher=CRC Press |year=2008 |isbn=978-1-4200-6444-5}}</ref><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 |url-access=registration |url=https://archive.org/details/guinnessbookofan00wood |publisher=Enfield, Middlesex : Guinness Superlatives }}</ref>

As a rule of thumb, a [[wing loading]] of 25&nbsp;kg/m<sup>2</sup> is considered the limit for avian flight.<ref name=Meunier/> A number of estimates related to wing loading have been produced for ''Argentavis'', most notably the wing area, estimated at {{convert|8.11|m2|ft2|abbr=on}}, and the wing loading, estimated at 84.6 [[Pascal (unit)|N/m<sup>2</sup>]] (1.77&nbsp;lb/ft<sup>2</sup>), or about 8.64&nbsp;kg/m<sup>2</sup>.<ref name="Chatterjee07" /> The heaviest extant flying birds are known to weigh up to a maximum of {{convert|21|kg|lb|abbr=on}} (there are several contenders, among which are the European [[great bustard]] and the African [[kori bustard]]). An individual [[mute swan]], which may have lost the power of flight due to extreme weight, was found to have weighed {{convert|23|kg|lb|abbr=on}}.<ref name=Wood/>

== Paleobiology ==
=== Life history ===
Comparison with extant birds suggests ''Argentavis'' laid one or two eggs with a mass of around {{convert|1|kg|lb|abbr=on}} every two years. Climate considerations make it likely that the birds incubated during the winter, with members of a mated pair alternating between incubating and procuring food every few days. The young are thought to have been independent after some 16 months, but to not reach full maturity until they reached roughly twelve years of age. To maintain a viable population, no more than 2% of birds could have died each year. Because of its large size and ability to fly, ''Argentavis'' suffered hardly any predation, and mortality was mainly related to old age and disease in adults.<ref name=Palmqvist/>

=== Flight ===
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. This is further supported by skeletal evidence, which suggests that its breast muscles were not powerful enough to enable flapping of the wings 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> Studies on [[condor]] flight indicate that ''Argentavis'' was fully capable of flight in normal conditions, as modern large soaring birds spend very little time flapping their wings regardless of environment.<ref>{{cite journal |last1=Williams |first1=H. J. |last2=Shepard |first2=E. L. C. |last3=Holton |first3=Mark D. |last4=Alarcón |first4=P. A. E. |last5=Wilson |first5=R. P. |last6=Lambertucci |first6=S. A. |date=13 July 2020 |title=Physical limits of flight performance in the heaviest soaring bird |journal=Proceedings of the National Academy of Sciences |volume=117 |issue=30 |pages=17884–17890 |bibcode=2020PNAS..11717884W |doi=10.1073/pnas.1907360117 |pmc=7395523 |pmid=32661147 |doi-access=free}}</ref>

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 had gained some vertical distance, meaning that, especially for takeoff, ''Argentavis'' would have depended on the wind.<ref name="c&t1983" /> ''Argentavis'' may have used mountain slopes and headwinds to take off, and probably could manage to do so even from gently sloped terrain with little effort. It may have flown and lived much like the modern [[Andean condor]], scanning large areas of land for carrion. It is probable that it utilised thermal currents to stay aloft, and it has been estimated that the minimal velocity for ''A. magnificens'' is about {{convert|11|m/s|ft/s}} or {{convert|40|km/h|mph}}.<ref name="Vizcaino" /> 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.<ref name="Chatterjee07"/>

=== Predatory behavior ===
''Argentavis''{{'}} [[territory (animal)|territories]] probably measured more than {{convert|500|km2|sqmi}}, which the birds screened for food, possibly utilizing a north–south flying pattern to avoid being slowed by adverse winds. This species seems less [[aerodynamic]]ally suited for [[predation]] than its relatives and probably preferred to scavenge for carrion. ''Argentavis'' may have used its wings and size to intimidate metatherian mammals and small phorusrhacids to take over their kills.<ref name="Tambussi"/><ref name="Palmqvist"/> [[Phorusrhacidae|Phorusrhacids]] were the largest land predators in Miocene South America, and probably the biggest threats that ''Argentavis'' faced, with the largest species that coexisted with ''Argentavis'', ''[[Devincenzia]]'', weighing up to {{convert|350|kg|lb|0}}.<ref>{{cite journal |last1=Blanco |first1=Rudemar Ernesto |last2=Jones |first2=Washington W |date=2005 |title=Terror birds on the run: a mechanical model to estimate its maximum running speed |url=https://www.researchgate.net/publication/7664536 |journal=Proceedings of the Royal Society B: Biological Sciences |volume=272 |issue=1574 |pages=1769–1773 |doi=10.1098/rspb.2005.3133 |pmc=1559870 |pmid=16096087}}</ref> Torres Etchegorry & Degrange (2024) suggested that ''Argentavis'' was a scavenger or even a [[Kleptoparasitism|kleptoparasitic]] bird, living in open areas without much vegetation, based on its probable brain morphology inferred from [[endocast]] reconstruction.<ref>{{cite journal |last1=Torres Etchegorry |first1=M. |last2=Degrange |first2=F. J. |title=Insights into ''Argentavis magnificens'' (Aves, Teratornithidae) lifestyle based on neuroanatomy |journal=Journal of Anatomy |year=2024 |doi=10.1111/joa.14184 |pmid=39626195 }}</ref>

== References ==
{{Reflist|30em|refs=
<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|doi=10.1093/auk/100.2.390 }}</ref>
<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=de |journal=Biologia Generalis |volume=19 |pages=403–443}}</ref>
<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=https://ameghiniana.org.ar/index.php/ameghiniana/article/view/966/1733}}</ref>
<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=es |url=http://www.ciencias.uma.es/publicaciones/encuentros/ENCUENTROS64/aves.html |archive-url=https://web.archive.org/web/20010513084248/http://www.ciencias.uma.es/publicaciones/encuentros/encuentros64/aves.html |url-status=dead |archive-date=2001-05-13 }}</ref>
}}

== Further reading ==
* {{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) | journal = Contributions in Science |publisher=Natural History Museum of Los Angeles County | volume = 330 | pages = 59–68 | doi = 10.5962/p.208145 | s2cid = 197586985 | doi-access = free }}
* [[Peter Wellnhofer|Wellnhofer, Peter]] (1996): ''The Illustrated Encyclopedia of Pterosaurs''. Barnes and Noble Books, New York. {{ISBN|0-7607-0154-7}}

== External links ==
* [https://web.archive.org/web/20180419025443/http://argentavis.net/ Argentavis information] Website about the ''Argentavis magnificens''
* [http://news.bbc.co.uk/2/hi/science/nature/6262740.stm BBC News: Ancient American bird was glider] – [[BBC News]] article
* [https://web.archive.org/web/20090903034253/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] – ''[[Daily Telegraph]]'' article
* [https://web.archive.org/web/20160815063427/http://archive.cosmosmagazine.com/news/flight-secrets-largest-bird-ever-revealed/ Secret of flight for world's largest bird revealed] – ''COSMOS'' magazine article
* [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''

{{Accipitrimorphae|C.|state=collapsed}}
{{Taxonbar|from1=Q645107|from2=Q17351700}}

[[Category:Birds of prey|†Argentavis]]
[[Category:Cerro Azul Formation]]
[[Category:Fossil taxa described in 1980]]
[[Category:Fossils of Argentina]]
[[Category:Huayquerian]]
[[Category:Miocene birds of South America]]
[[Category:Neogene Argentina]]
[[Category:Prehistoric bird genera]]
[[Category:Teratornithidae]]