Earth formed around 4.54 billion years ago, approx 1/3rd the age of universe by collisions in the giant disc-shaped cloud of material that also formed the Sun . At initial there is no life, no oxygen, no land, no water on the Earth. There is only heat, burning floating lava's. Volcanic outgassing probably created the primordial atmosphere and then the ocean. The creation of Earth's Moon occurred due to the collision with a planet-sized body named Theia ed. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water on the surface. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. In