Argentavis is an extinct genus of teratornithid known from three sites in the Epecuén and Andalhualá Formations in central and northwestern Argentina dating to the Late Miocene (Huayquerian).

[4] These fossils had been exposed in brown-red silt and clay sediments from the Epecuén Formation in Salinas Grandes de Hidalgo in Atreucó, Argentina.

[3] 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.

Campbell assigned it to A. magnificens based on the development of grooves and tubercles on the bone,[7] however due to the lack of overlap with the holotype and its robust morphology a 2011 article classified it as phorusrhacid.

[8] 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.

[citation needed] Estimates for Argentavis' wingspan vary widely depending on the method used for scaling, i.e. regression analyses or comparisons with the California condor.

[17] Meanwhile, the sarus crane is the tallest flying bird alive, at up to 1.8 m (5 ft 11 in) tall, standing about as high as Argentavis due to its long legs and neck.

[21] 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.

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 11 metres per second (36 ft/s) or 40 kilometres per hour (25 mph).

[22] 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.

[citation needed] Argentavis' territories probably measured more than 500 square kilometres (190 sq mi), which the birds screened for food, possibly utilizing a north–south flying pattern to avoid being slowed by adverse winds.