Few prehistoric animals have captured the imaginations of palaeontologists as has Argentavis magnificens.
The bird was the same size as a light aircraft, had a 20in skull and weighed 150lb.
But with relatively little muscle to flap its wings, how it remained in the air has been the subject of speculation.
Using software designed for helicopters, scientists from the Museum of Texas Tech University have shown how the giant bird took off, remained aloft and landed.
Like eagles and condors, Argentavis relied on the wind for lifting power. It was concluded that Argentavis would have been incapable of flight powered entirely by flapping its wings, or even of a standing take-off, because it lacked enough muscle power.
The economical high-performance glider had a turning radius of 100 feet, short enough for it to circle around within a thermal as it rose up to search the Angentinian pampas for prey.
It seems that Argentavis was a lazy glider that relied either on updrafts in the rocky Andes or thermals on the grassy plains to provide enough lifting power. The bird also relied on what the team calls “slope soaring” over the Andes, harnessing the rising air caused by upward deflection of wind over a ridge or a cliff.
The constant east wind that originates in the South Atlantic and heads across the pampas against the Andean foothills would create a steady source of rising air along the line of the slope. This enabled Argentavis to cover long distances with little effort, cruising for up to 200 miles at speeds exceeding 40mph.
The hardest part would be taking off from the ground. It would have been impossible to take off from a standing start. The difficulties are highlighted by the example of a living bird that is three times lighter than Argentavis. The 40lb Great Kori Bustard can only take off by running like a taxiing aircraft. The Argentavis used techniques used by hang-glider pilots such as running on sloping ground to get thrust.