Oversimplification due to a lack of actual data. Also, I think each generation has very interesting histories to tell. But we have lost almost all of them, exc

Oversimplification due to a lack of actual data. Also, I think each generation has very interesting histories to tell. But we have lost almost all of them, except for an infinitesimal very last bit. So we don't know what has happened in hundreds of thousands of generations, from the first cordates to therapsides to primates, that could perfectly explain it all.