Earth’s history is divided into major time periods called Geological Eras. Each era marks important changes in life and environment.
🔹 Precambrian Time (4.6 billion – 541 million years ago) The earliest phase of Earth. Formation of the planet, oceans, and first simple life like bacteria and algae.
🔹 Paleozoic Era (541 – 252 million years ago) Life begins to flourish. Fish, amphibians, and early reptiles appear. First forests grow on land.
🔹 Mesozoic Era (252 – 66 million years ago) Known as the “Age of Reptiles.” Dinosaurs dominate the Earth. First birds and mammals evolve.
🔹 Cenozoic Era (66 million years ago – Present) The “Age of Mammals.” Modern animals and humans develop. Continents take their current shape.
📌 These eras show how Earth transformed from a lifeless planet into a world full of diverse life.