As time passes, the organic components of bone (mostly fat) are lost primarily through bacterial action.
In other words, they may no longer be in their primary context.
When the bones of our early ancestors are found in the same geological strata as those of other animals that are known to have lived only during a specific time period in the past, we assume that these ancestors must also have come from that time.
At the same time, percolating ground water deposits trace amounts of fluorine and other elements, such as uranium, into the bone.
As a result, the amount of fluorine Fluorine analysis can be used only as a relative dating method because the rate of decay and the amount of dissolved minerals in the ground water varies from site to site.
It had been cleverly carved to fit the skull and stained to look ancient.