History of Life on Earth By megaflops 1 CE Earth forms first day of earth Period: 1 CE to 1797 Pre-Cambrian 351 3.8 BYA First Life on Earth Replicating molecules (the precursors of DNA) form. Period: 1797 to 1924 Paleozoic Period: 1924 to 2005 Mesozoic 1992 Extinction of Dinosaurs 65 mya Period: 2005 to 2020 Cenozoic
