here goes another bit of whatever I have left for a reputation.

"He showed photographs of ancient Sumerian carvings and etchings showing what he said were alien gods dressed in space helmets and suits."

You use to be able to see exactly this up at Hopi. Not carvings but Katchina. The live ones. Another thing that impressed me was when I was told the Katchina's appearence isn't figural or alliterative, "this is exactly the way these people appeared to us".