Have you ever taken up genealogy? If you go back more than three generations and try to find all your ancestors, not just your paternal lineage, you run into gaps. If you cannot trace your ancestry back ten generations with certainty, how can you expect paleontologists to trace ancestries back millions of generations without error?
Like any genealogy, it's a work in progress.
All gaps in my genealogy are obviously occasions when one of my ancestors coupled with a god.