Download PDF June 1, 1980

 

ARGENTAVIS MAGNIFICENS: WORLD'S LARGEST FLYING BIRD

by
David H. Rhys

Research Associate, Geoscience Research Institute

Recently the Los Angeles County Natural History Museum displayed parts of a skeleton of the biggest known bird that ever flew. Looming over the entrance hall, a black silhouette of Argentavis magnificens spans its wings over 8 m and stands 3.5 m from tip of tail to end of beak. This is almost twice the size of Teratornis merriami which, until now, had been considered the largest size to which flying avians could evolve. Argentavis magnificens (new genus and species) has now wrested the title of “World’s largest flying bird” from Osteodotornis orri, the gigantic marine bird from the Miocene of California.

E. Tonni and R. Pascual of the National Museum of La Plata, Argentina, uncovered the fossil remains of A. magnificens from the banks of Salinas Grandes de Hidalgo in the Argentine province of La Pampa, 400 miles SW of Buenos Aires. Their collection included portions of the skull, the coracoid, the left humerus (incomplete), a portion of the ulna and right radius, the right tibiotarsus, one end of metacarpal II, a portion of meta- carpal III, and a shaft of right tarsometatarsus.

Systematics: Order. Accipitriformes
                      Family. Teratornithidae
                      New genus and species. Argentavis magnificens
Etymology:   Greek teretos (wonder) and ornis (bird)
                      Latin argentum (silver) and avis (bird)

This discovery did not come to the attention of the international scientific world until K. E. Campbell, curator of the Los Angeles County Natural History Museum and specialist in teratorns of Rancho La Brea, visited La Plata’s Museum and with Tonni began a detailed study of the collected fossils. Their results have now been published by the Los Angeles County Natural History Museum.

The fossils were found in Argentina’s central plain which is characterized by a flat, semi-arid topography. Dated in the Miocene epoch, the current evidence suggests an open grassland based on an abundance of fossil herbivorous animals. A large number were rodents on which the A. magnificens is thought to have fed. This latter supposition is based on studies of jaw articulation in comparison with recent similar birds. It is further supposed that the heads were not naked as are those of vultures, but covered with feathers.

The large wing size would limit this bird to more open areas, as maneuverability around trees and shrubs would seem difficult. Feather size is estimated to be 1.5 m long and 20 cm wide. It is not presently known if this teratorn actively flew by flapping its wings or if it mostly soared as do present-day condors.

An expedition to Argentina in 1981 is planned to search for further fossils of this most magnificent bird.