[Nateman]

I bet they were assuming the fossils of mammoths were those of men. That is the origin of the Titan myths in Greece.

[Ruy Dias de Bivar]

I remember reading how early explorers in America often found mastodon bones lying on the surface of the ground. Some places had so many the explorers used the ribs for shelter for their tents.

[PIF]

Actually not. There are stone carvings to the claimed effect. how genuine they are is anyone’s guess. And that was dinosaur bones, not mammoth bones.