Introduction
The timeline of Earth is a journey through billions of years, from the formation of the planet to the present day. It encompasses major geological, biological, and climatic events that have shaped the world we know today.
Timeline
Precambrian
| Era/Period | Timeframe | Key Events |
|---|
| Hadean | 4.6 to 4 billion years ago | - Formation of Earth <br> - Differentiation into core, mantle, and crust <br> - Heavy bombardment by asteroids and comets |
| Archean | 4 to 2.5 billion years ago | - Formation of the first continents <br> - Emergence of early life (prokaryotes) <br> - Development of the atmosphere and oceans |
| Proterozoic | 2.5 billion to 541 million years ago | - Oxygenation of the atmosphere (Great Oxidation Event) <br> - Appearance of eukaryotic cells <br> - First multicellular organisms |
Phanerozoic Eon
Paleozoic Era
| Era/Period | Timeframe | Key Events |
|---|
| Cambrian | 541 to 485 million years ago | - "Cambrian Explosion" of diverse life forms <br> - Development of hard-bodied organisms <br> - Origin of major animal phyla |
| Ordovician | 485 to 444 million years ago | - Marine biodiversity flourished <br> - First vertebrates <br> - Colonization of land by plants |
| Silurian | 444 to 419 million years ago | - Evolution of jawed fish <br> - Early terrestrial arthropods <br> - Vascular plants spread on land |
| Devonian | 419 to 359 million years ago | - Age of Fishes <br> - First amphibians <br> - Plants and forests become widespread |
| Carboniferous | 359 to 299 million years ago | - Extensive coal forests <br> - Evolution of reptiles <br> - High oxygen levels in the atmosphere |
| Permian | 299 to 251 million years ago | - Pangea supercontinent formation <br> - Diversification of reptiles <br> - End-Permian mass extinction (largest in Earth's history) |
Mesozoic Era
| Era/Period | Timeframe | Key Events |
|---|
| Triassic | 251 to 201 million years ago | - Recovery from Permian extinction <br> - Rise of dinosaurs and mammals <br> - First pterosaurs and marine reptiles |
| Jurassic | 201 to 145 million years ago | - Dinosaurs dominate terrestrial ecosystems <br> - Evolution of birds <br> - Early mammals and flowering plants appear |
| Cretaceous | 145 to 66 million years ago | - Flowering plants diversify <br> - Peak of dinosaur evolution <br> - Ended by a mass extinction event (asteroid impact) |
Cenozoic Era
| Era/Period | Timeframe | Key Events |
|---|
| Paleogene | 66 to 23 million years ago | - Mammals diversify and evolve into major groups <br> - Birds and reptiles radiate <br> - Climate shifts from warm to cooler conditions |
| Neogene | 23 to 2.6 million years ago | - Grasslands expand <br> - Evolution of hominins <br> - Continents move toward current positions |
| Quaternary | 2.6 million years ago to present | - Repeated glacial and interglacial cycles <br> - Rise of modern humans <br> - Extinction of many large mammals |
Anthropocene (Proposed Epoch)
| Timeframe | Key Events |
|---|
| - Human activity reshapes geology and ecosystems <br> - Industrialization, urbanization, and climate change <br> - Mass extinction and biodiversity loss |
Conclusion
Earth's timeline is a testament to constant change and evolution, driven by geological forces, climatic shifts, and biological innovations. From the molten beginnings of the Hadean to the complex ecosystems of today, each era has contributed to the planet's dynamic history. The proposed Anthropocene underscores the significant impact humans have had on the environment, marking a new chapter in this ancient story.
