Biology Timeline By zholder5 3650 BCE Earliest Evidence of Life 3650 BCE Precambrian Era 2500 BCE First Photosynthetic/autotrophic bacteria appear 2200 BCE First Great Extinction, oxygen producing bacteria "poison" the environment, age of aerobic organisms begins 1750 BCE First Eukaryotes Appear 650 BCE Sexual Reproduction 650 BCE Multi-cellular Life Appears 550 BCE Paleozoic Era 550 BCE "Cambrian Explosion"---- huge diversity and complexity increase in a relatively short period of time 505 BCE Marine Invertebrates Appear 438 BCE Great Extinction, fish appear 408 BCE Land Plants Appear 360 BCE Great Extinction, amphibians appear 286 BCE Reptiles Appear 245 BCE Mesozoic Era 245 BCE Great Extinction, seed plants appear 208 BCE Great Extinction, mammals and dinosaurs appear 114 BCE Primitive Birds Appear 66 BCE Cenozoic Era 66 BCE Great Extinction, dinosaurs disappear 60 BCE Primates Appear 38 BCE Anthropoids Appear 37 BCE Primitive Horses Appear 1 BCE Humans Appear 2 Historical Date of Jesus Birth 2 USA's Declaration of Independance