But there is another kind of argument:
In the developed countries, where the ground is being upset all the time, you have many paleontologists who hunt for old bones and can stop construction works whenever necessary (done for the High Speed Train tracks, for example). You find many many more archaeologists, paleontologists in those countries (where there are universities) than in Africa, and yet, we can't find ancestors older than those found in Africa. One of the earliest Dinosaur discoveries was done in Bernissart, Belgium.
In Africa, there are 2 phenomenons: first, the climate is very dry, which keeps things intact for a longer time, but most importantly, there is the Rift valley, which enables old bones to return back to the surface after having been underground for aeons. Scientists like that area because it uncovers the past like an open book.

And about eternity...well, in the 20's, Hubble discovered that spiral nebulae were in fact very very distant milky ways just like ours and they had to be called galaxies and so was ours.
This led to the Big Bang theory through Georges Lemaître's primitive atom. This meant that even the Universe itself started, was born, had a time 0 !!! Which means that the universe evolves, changes and will die.
Something that is eternal does not start, is not born as eternity goes both ways back to time and to the future. So, the bottomline is....nothing is eternal...Least of which our lifetime on Earth.

Raoul