-
Bacteria began harnessing sunlight to make sugar from carbon dioxide and water, just like green plants today. These microbes pumped out oxygen as a waste product, creating the oxygen-rich atmosphere we have today.
-
Earth froze over again, twice, in the space of 200 million years. The ice stretched all the way from the poles to the equator.
-
This apparent 'explosion' may be partly down to better fossilization, as many animals now had hard shells.
-
Plants were the first to take up permanent residence on land. The first land plants were relatives of green algae, but they rapidly diversified.
-
The Ordovician period was a time when life flourished. But towards its end, the world cooled dramatically and ice sheets spread from the poles.
-
With plants well-established on land, the next step was for animals to move out of the water.
-
When the first reptiles appeared, Earth was in the middle of a long cold snap called the Late Paleozoic Ice Age. Reptiles evolved from newt-like amphibians.
-
For the last time, all Earth's continents came together to form one giant supercontinent. Known as Pangaea, it was surrounded by a world-spanning ocean called Panthalassa.
-
Just as the reptiles were flourishing, life on Earth faced perhaps its greatest challenge. The Permian extinction was the worst mass extinction in the planet's history, obliterating up to 96% of marine species and similar numbers of land animals.
-
At the same time that the dinosaurs were spreading and diversifying, the first mammals evolved.