More than 20 of them have turned up across the American West, including one unearthed in a Colorado backyard in 2008. They have been found by construction crews, artifact collectors, and in one case by a man hand-digging an irrigation canal.

When I was very young my brothers, friends and I used to play down by the creek that ran past our place. After the spring flood had receded we used to find all kind of fossils arrow heads and stuff. We never thought to save any of it though.