Fanerozoic

The Phanerozoic Eon is the current geologic eon, which began about 538.8 million years ago. It is the time in Earth's history during which complex life, characterized by easily fossilized hard shells and skeletons, became abundant. The name "Phanerozoic" comes from the Greek words phaneros meaning "visible" and zoe meaning "life". This eon is divided into three eras: the Paleozoic, the Mesozoic, and the Cenozoic.

The Paleozoic Era, meaning "ancient life," lasted from 538.8 to 251.9 million years ago. It witnessed the diversification of marine life, the emergence of land plants and animals, and ended with the Permian-Triassic extinction event, the most severe extinction in Earth's history.

The Mesozoic Era, or "middle life," spanned from 251.9 to 66 million years ago. This era is famously known as the "Age of Reptiles," dominated by dinosaurs. It also saw the evolution of mammals, birds, and flowering plants. The Mesozoic ended with the Cretaceous-Paleogene extinction event, which wiped out the non-avian dinosaurs.

The Cenozoic Era, or "new life," began 66 million years ago and continues to the present. It is characterized by the rise of mammals and birds to prominence. The Cenozoic has seen significant climatic shifts, including ice ages, and the evolution of humans.