If you check out this artifact up above, this is from a Mayan culture that lived in Mexico. Their legends tell of flying hybrid creatures that stalked local villages. In many artifact drawings there are references to gods from the skies visiting the early indigenous people of Mexico dating all the way back to Mayan era.
So what comes to mind, Aliens that's for sure. It sounds pretty fictitious, I know. But, then you hear a story from a local police officer that had a nasty encounter with one of these floating creatures. He says he still has horrific dreams to this day. The story from the officer was very intriguing.
The investigators from Monster Quest actually suggested that this could be an alien species visiting earth. I was kind of amazed to hear this on Monster Quest since the show was suppose to be about monsters. But, when I think about it, half the monsters seen out in the world might actually be Aliens. So I guess it was only a matter of time before an investigator linked one of these monsters to an extraterrestrial race.
This show was awesome, if you get a chance I definitely suggest checking it out. Try youtube, I looked and they had it up there.