For centuries, many of the Native American tribes who live in the western half of the US have told stories of creatures known as thunderbirds. Big (and fierce) enough to feed on full-grown bison, with wings so powerful that they could produce thunderclaps, the birds hold a special place in tribal lore.

But could thunderbird legends be based on animals still living in remote parts of America?

In 1890, two Arizona cowboys claimed to have killed a gigantic, featherless bird. Photographs (which disappeared long ago) are said to have shown a strange creature with an alligator-like head and a wingspan longer than the length of a barn. Some believe that the bird’s description matches that of the extinct Pteranodon (see above).

In the years since, sightings of similar flying “monsters” have been surprisingly common, particularly in South Texas. According to one terrified San Antonio eyewitness, an enormous, black creature with “stooped-up shoulders” flew over his car less than ten years ago. In 1976, three school teachers reported that their car had been similarly “buzzed.”

Yet another reputable witness claims he once saw two of the birds perched on a hillside. “These creatures were so huge they looked like the size of small planes,” he said. “All of the sudden one of them jumped off dropped off the top of the mountain, came down the front of the mountain and all the sudden these huge wings just spread out. I would say the wings were at least a 20-foot wingspan.”