Interesting how the skull's all placed on old rags - as if it's in a crate. My theory is that Indy... doesn't find it / loot it from the Incan/Aztec temple. It's already in one of those crates in the Government Warehouse where the Ark also resides. Indy has to recover it from the warehouse* and return it to the temple for some reason, perhaps to send a signal and stop an alien invasion (somewhat like the Humpback whale thing in that one Star Trek movie). * Didn't the early Indy teaser site have a crate stamped with a number similar, but not identical, to the Ark's?