The largest flying bird they have discovered so far lived 6 million years ago. Argentavis magnificens had 70 kilos and 7 meters south length. At the University of Technology Texas Museum they wanted to know how it was carried out to fly. One study concluded that the bird was a glider, that is, it used the air currents that ascended to raise its great weight, without stirring wings for a long time. As they have seen, this bird would not have been able to fly constantly stirring its wings, as it would need 3.5 times the energy it obtained from food.