As most of these sighters described large black birds with vulture-like heads and similar wing tips. Also, bioligists have observed endless condors that enjoy soaring and 'riding' air currents even those that precede thunderstorms... that would definately account for the native american legend...
and as for the prehistoric varieties of condors- I've often wondered just how any one can know for certain that any species is completely extinct.
And what a creepy ufo report from texas!! by far the most convincing I've ever heard- and fighter pilots? Wonder if the FBI has sh** a chicken over this yet and how the encounter was leaked in the first place... spooky stuff, Diantha!!