Prehistoric Time Line, Geologic Time Scale, Photos, Facts, Maps, and More
Humans have walked the Earth for 190,000 years, a mere blip in Earth's 4.5-billion-year history. A lot has happened in that time. Earth formed and oxygen levels rose in the foundational years of the Precambrian. The productive Paleozoic era gave rise to hard-shelled organisms, vertebrates, amphibians, and reptiles. Dinosaurs ruled the Earth in the mighty Mesozoic. And 64 million years after dinosaurs went extinct, modern humans emerged in the Cenozoic era.
Related: Geologic Time and Bedrock Geology