There is a story that in April 1890, two cowboys in Arizona managed to shoot to death a giant birdlike creature with an enormous wingspan. It was said it had smooth skin, and featherless wings like a bat. Its face resembled an alligator. Interestingly, this description has more than a cursory similarity to the prehistoric pterodactyl. They dragged the carcass back to town, and it was pinned, wings outstretched across the entire length of a barn. There is supposed to be a picture of this event, that may or may not have been published in the local newspaper, the Tombstone Epitaph. Despite numerous people who have claimed to have seen this photograph recently, no one has ever been able to produce a copy of the picture nor make historic corroboration that this event ever occurred, and it is most likely an urban legend.
There have also been thunderbird sightings more recently. In the 1960s and 1970s, sightings of a large bird the size of a Piper Cub airplane were made in Washington, Utah, and Idaho. On occasion, this was accompanied by large footprints or other purported evidence.
Some cryptozoologists have theorized the thunderbird myth to be based on sightings of a real animal that has dwindled in population of late. Initially this was scoffed at by skeptics saying a bird that large could not have flown. This is not outside the realm of possibility. The prehistoric vulture-like Teratornis incredibilis had a wingspan of anywhere from 5 m up to 7 m (16 to 24 ft) and is believed to have been capable of flight. Cryptozoologists also posit that the thunderbird was associated with storms because they followed the drafts to stay in flight, not unlike a modern eagle rides mountain upcurrents. Noted cryptozoologist John Keel claimed to have mapped several thunderbird sightings and found that they corresponded chronologically and geographically with storms moving across the United States.
In 2002, a new sighting in Alaska was announced.