If the ancient handprint in Canada didn't convince you that we might be wrong about when the first humans appeared, perhaps this will. It's a footprint, and it's firmly embedded in a coal seam in Fisher Canyon, Nevada.
Coal takes a very long time to form. This particular seam is approximately fifteen million years old, so the footprint has to be of a similar age. Also, it's clearly not a barefoot; whoever made it was wearing a shoe. What we have here is either fast-forming coal, or an ancient astronaut.