This usually requires what is commonly known as a "dating method".
Outside the range of recorded history, calibration of the 14 clock is not possible.
This means the above calculations are only evolution speculation and NOT backed up by real science.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.