Thunderbirds

They once existed, enormous birds of prey which dwarfed any known flying species living today.  Teratorns, lived as recently as 12,000 years ago in the Americas.   These large birds may have been the basis for the Native American legends of Thunderbirds.  Large birds that meet the criteria of those supposed mythical beast have been seen from Alaska to Argentinian in modern times.    Could it be that these sightings are merely a case of mistaken identity or is it possible that a small population of these creatures still exist in some remote corner of the world?