In Graham Hancock’s latest book, “America Before”, he mentions a mastodon bone that was found in San Diego county that was found planted in a vertical position in the ground as presumably some sort of marker. The bone was dated to around 130,000 years ago. The assumption is a human being put it there during the inter glacial between the last two ice ages.
Needless to say this is controversial.
In the late 1990s I met a woman anthropologist at an east coast bar who had left California. She told me there was a lot of controversy about human remains or traces there that were over 100,000 years old.