042 The Fundamental Philosophy of Earth Science

• Hadean eon

• Precambrian era

• 4.6 billion to 4 billion years ago

• Formation of the Earth and Moon

• Heavy astronomical activity

• Archean eon

• Precambrian era

• 4 billion to 2.5 billion years ago

• Formation of Earth’s crust

• First signs of life

• Prokaryotes

• Proterozoic eon

• Precambrian era

• 2.5 billion to 541 million

• Oxygenation of atmosphere

• First eukaryotes

• Phanerozoic eon

• Paleozoic era

• 541 million to 252 million years ago

• Cambrian period

• 541 million to 485 million years ago

• Cambrian Explosion

• Ordovician period

• 485 million to 444 million years ago

• First land plants

• Marine biodiversity

• Silurian

• 444 million to 419 million years ago

• First jawed fish

• Vascular plants

• Devonian

• 419 million to 359 million years ago

• Age of fish

• First amphibians

• Carboniferous

• 359 million to 299 million years ago

• Coal swamps

• First Reptiles

• Permian

• 299 million to 252 million years ago

• Pangaea forms

• Mass extinction

• Mesozoic era

• 252 million to 66 million years ago

• Triassic

• 252 million to 201 million years ago

• First dinosaurs

• First mammals

• Jurassic

• 201 million to 145 million years ago

• Age of dinosaurs

• First birds

• Cretaceous

• 145 million to 66 million years ago

• Flowering plants

• Mass extinction

• Cenozoic era

• 66 million years ago to present

• Paleogene

• 66 million to 23 million years ago

• Mammals diversify

• Neogene

• 23 million to 2.58 million years ago

• First hominins

• Quaternary

• 2.58 million years ago to present

• Ice Ages

• Rise of humans