Quick reference to Earth's history
This chronology outlines major events in Earth's history, measured in millions of years ago (mya leftmost column). The rightmost column represents the time elapsed since Earth's formation, allowing events to be viewed in terms of how long it took before it occur. Many of these events are cyclical: supercontinents form and eventually break apart, ice ages advance and retreat, and periods of rapid evolutionary diversification are followed by mass extinctions - often occurring in tandem.
| Time mya | Event | Invert mya | |
|---|---|---|---|
| 4600 | π | Earth formed from debris around the solar protoplanetary disk. | 0 |
| 4500 | π | Moon formed, likely due to a collision between Early Earth and a protoplanet Theia. Giant-impact hypothesis | 100 |
| 4100 | βοΈ | Start of the Late Heavy Bombardment - disproportionately large number of asteroids and comets collided into the Earth | 500 |
| 3800 | βοΈ | End of the Late Heavy Bombardment. | 800 |
| 3636 | π | Formation of the Vaalbara first supercontinent. | 964 |
| 3600 | π¦ | Last Universal Common Ancestor (LUCA) β hypothesized ancestral cell from which all life emerged. | 1000 |
| 3500 | π¦ | Earliest confirmed life: prokaryotes (single-celled organisms without a nucleus, such as bacteria). Algal mats - microbial mat. | 1100 |
| 2900 | βοΈ | Start of the Pongola glaciation - oldest known ice age. | 1700 |
| 2803 | π | Formation of the Ur supercontinent. A small, barren, volcanic landmass with dark rocky terrain, surrounded by shallow seas. | 1797 |
| 2750 | βοΈ | End of the Pongola glaciation. | 1850 |
| 2720 | π | Formation of the Kenorland supercontinent. Was a vast, barren, ancient supercontinent with a rugged, volcanic landscape, mountain ranges, and shallow seas. | 1880 |
| 2460 | π¨ | Great Oxidation Event - rise in Earth's oxygen levels, primarily due to photosynthetic microbes, which dramatically altered the atmosphere and enabled the evolution of complex life. | 2140 |
| 2400 | βοΈ | Start of the Huronian glaciation (first known Snowball Earth event - the planet's surface became nearly entirely frozen). | 2200 |
| 2100 | βοΈ | End of the Huronian glaciation. | 2500 |
| 2023 | βοΈ | Asteroid impact formed the Vredefort crater, the largest known on Earth. | 2577 |
| 1991 | π | Formation of the Atlantica supercontinent. With a mostly flat, rocky landscape, surrounded by shallow seas. | 2609 |
| 1850 | π¦ | Earliest confirmed unicellular eukaryote (complex cell with a nucleus). | 2750 |
| 1820 | π | Formation of the Columbia supercontinent. With vast mountain ranges, shallow inland seas. | 2780 |
| 1500 | π¦ | Evolution of biological carbon fixation β conversion of COβ into organic compounds. | 3100 |
| 1430 | π | First fungi evolved. | 3170 |
| 1200 | 𧬠| Bangiomorpha β earliest known organism with differentiated, specialized cells; oldest known sexually reproducing organism. Origin of sexual reproduction | 3400 |
| 1130 | π | Formation of the Rodinia supercontinent. Rugged mountain ranges, barren rocky landscapes, and extensive inland seas. | 3470 |
| 760 | π | Otavia β oldest known animal fossil (sponges). Animals are heterotrophic, meaning they consume other organisms for energy, often through ingestion, digestion, and absorption. | 3840 |
| 720 | βοΈ | Start of the Cryogenian Ice Age (Snowball Earth events). | 3880 |
| 636 | βοΈ | End of the Cryogenian Ice Age. | 3964 |
| 635 | π | Ediacaran biota β earliest known complex multicellular organisms. | 3965 |
| 633 | π | Formation of the Pannotia a short-lived supercontinent with fragmented landmasses, shallow inland seas, and a mostly barren surface | 3967 |
| 580 | π | First cnidarians - group of simple animals, including jellyfish, corals, and hydras, characterized by their stinging cells (cnidocytes) used for capturing prey and defense. | 4020 |
| 550 | π | Formation of the Gondwana a massive southern supercontinent with diverse landscapes, including mountains, vast deserts and extensive coastlines. Later it will be with lush forests and animals. | 4050 |
| 538 | π | Cambrian explosion β rapid diversification of complex life. First fish, creatures with hard outer bodies appeared. | 4062 |
| 497 | π | Start of the Great Ordovician Biodiversification Event - a time when a wide variety of new marine life forms appeared, including many new species of fish, shellfish, and other sea creatures, increasing the complexity of ocean ecosystems. | 4103 |
| 475 | π± | First land plants (mosses and liverworts). | 4125 |
| 460 | βοΈ | Start of the Hirnantian glaciation caused Late Ordovician mass extinction. | 4140 |
| 445 | π | Late Ordovician mass extinction - a major event that wiped out about 85% of marine species, likely caused by a sudden ice age and dramatic climate changes. | 4155 |
| 420 | βοΈ | End of the Hirnantian glaciation. | 4180 |
| 414 | π | Pneumodesmus β oldest known air-breathing animal (myriapod). | 4186 |
| 400 | π | Earliest fossils of insects. | 4200 |
| 400 | π¦ | First tetrapods (four-limbed vertebrates, not yet able to walk on land). | 4200 |
| 385 | π³ | First modern land ecosystems. | 4215 |
| 372 | π | Late Devonian mass extinction - a series of events that caused the loss of many marine species, particularly reef-building organisms, likely due to climate changes. | 4228 |
| 360 | βοΈ | Start of the Karoo Ice Age. | 4240 |
| 350 | π¦ | Fully developed tetrapods appeared. Evolution of tetrapods | 4250 |
| 313 | π | First reptiles (synapsids and sauropsids) - are cold-blooded animals with scaly skin, lay eggs with hard shells, and have lungs for breathing. | 4287 |
| 275 | π | Reptiles (pelycosaurs and therapsids) dominated temperate zones. Sauropsids and amphibians thrived in hotter, drier environments near the equator. | 4325 |
| 255 | βοΈ | End of the Karoo Ice Age. | 4345 |
| 252 | π | PermianβTriassic extinction event - the largest mass extinction in Earth's history, wiping out around 96% of marine species and 70% of terrestrial vertebrates, likely caused by volcanic activity, climate changes, and atmospheric disruptions. | 4348 |
| 243 | π¦ | Nyasasaurus β earliest known dinosaur. | 4357 |
| 235 | π | First crocodilians. | 4365 |
| 228 | π¦ | Pterosaurs β earliest flying vertebrates. | 4372 |
| 225 | π | First mammals - warm-blooded animals with hair or fur. | 4375 |
| 201 | π | TriassicβJurassic extinction event - wiped out many species, particularly large reptiles, and allowed dinosaurs to become the dominant land animals until 66 mya. | 4399 |
| 175 | π | Breakup of the Gondwana and Pangaea supercontinents. | 4425 |
| 150 | π¦ | Archaeopteryx β earliest known bird. Evolution of birds | 4450 |
| 150 | π | Termites β first eusocial animals (cooperative brood care, overlapping generations, division of labor). | 4450 |
| 130 | πΈ | First flowering plants (fruits). | 4470 |
| 66 | βοΈ | Asteroid impact formed the Chicxulub crater - a massive asteroid strike that contributed to CretaceousβPaleogene extinction event. | 4534 |
| 66 | π | CretaceousβPaleogene extinction event - the disappearance of the dinosaurs and many other species caused by an asteroid impact. | 4534 |
| 6 | π¦ | Upright-walking apes β ancestors of humans. | 4600 |
| 3 | π΅ | Homo habilis β earliest known representative of the genus Homo. | 4600 |
| 2 | π οΈ | First known stone tools. | 4600 |
| 2 | βοΈ | Start of the Quaternary Ice Age. | 4600 |
| 0 | π¨βπ» | We are here now | 4600 |