Timeline of natural history

Main articles: History of the Earth and Geological history of Earth

See also: Geologic time scale and Timeline of human evolution

This timeline of natural history summarizes significant cosmological, geological and biological events from the formation of the Universe to the rise of modern humans.

Formation of the Universe

Main article: Timeline of the Big Bang

• 13.7 ± 0.2 billion years ago (13,700 million years ago, or Ma): estimated age of the universe according to the Big Bang theory
• 13,200 Ma: age of the oldest known star, HE 1523-0901
• 12,700 Ma: age of the quasar CFHQS 1641+3755

The earliest Solar System

Main articles: Formation and evolution of the Solar System and Nebular hypothesis

In the earliest solar system history, the sun, the planetesimals and the jovian planets were formed. The inner solar system aggregated slower than the outer, so the terrestrial planets were not yet formed, including Earth and Moon.

• c. 4,570 Ma: A supernova explosion seeds our galactic neighborhood with heavy elements that will be incorporated into the Earth, and results in a shock wave in a dense region of the Milky Way galaxy. The Ca-Al-rich inclusions, which formed 2 million years before the chondrules, are a key signature of a supernova explosion.
• 4,567±3 Ma: Rapid collapse of hydrogen molecular cloud, forming a third-generation Population I star, the Sun, in a region of the Galactic Habitable Zone (GHZ), about 25,000 light years from the center of the Milky Way Galaxy.
• 4,566±2 Ma: A protoplanetary disc (from which Earth eventually forms) emerges around the young Sun, which is in its T Tauri stage.
• 4,560–4550 Ma: Proto-Earth forms at the outer (cooler) edge of the habitable zone of the Solar System. At this stage the solar constant of the sun was only about 73% of its current value, but liquid water may have existed on the surface of the Proto-earth, probably due to the greenhouse warming of high levels of methane and carbon dioxide present in the atmosphere.

Hadean Eon

Main article: Hadean

• 4,533 Ma: Hadean Eon, Precambrian Supereon and Cryptic era start as the Earth–Moon system forms, possibly as a result of a glancing collision between proto–Earth and the hypothetical protoplanet Theia. (The Earth was considerably smaller than now, before this impact.) This impact vaporized a large amount of the crust, and sent material into orbit around Earth, which lingered as rings for a few million years, until these rings condensed into the Moon. The Moon geology pre-Nectarian period starts. Earth was covered by a magmatic ocean 200 kilometres (120 mi) deep resulting from the impact energy from this and other planetesimals during the early bombardment phase, and energy released by the planetary core forming. Outgassing from crustal rocks gives Earth a reducing atmosphere of methane, nitrogen, hydrogen, ammonia, and water vapour, with lesser amounts of hydrogen sulfide, carbon monoxide, then carbon dioxide. With further full outgassing over 1000–1500 K, nitrogen and ammonia become lesser constituents, and comparable amounts of methane, carbon monoxide, carbon dioxide, water vapour, and hydrogen are released.
• 4,450 Ma: 100 million years after the Moon formed, the first lunar crust, formed of lunar anorthosite, differentiates from lower magmas. The earliest Earth crust probably forms similarly out of similar material. On Earth the pluvial period starts, in which the Earth's crust cools enough to let oceans form.
• 4,404 Ma: First known mineral, found at Jack Hills in Western Australia. Detrital zircons show presence of a solid crust and liquid water. Latest possible date for a secondary atmosphere to form, produced by the Earth's crust outgassing, reinforced by water and possibly organic molecules delivered by comet impacts and carbonaceous chondrites (including type CI shown to be high in a number of amino acids and polycyclic aromatic hydrocarbons (PAH)).
• 4,150 Ma: Unofficial Basin Groups Era starts.
• 4,100 Ma: Acasta Gneiss of Northwest Territories, Canada, first known oldest rock, or aggregate of minerals.
• 3,920 Ma: Unofficial Nectarian Era starts.
• 3920–3850 Ma: Late heavy bombardment of the Moon (and probably of the Earth as well) by bolides and asteroids, produced possibly by the planetary migration of Neptune into the Kuiper belt as a result of orbital resonances between Jupiter and Saturn.
• 3,850 Ma: Unofficial Lower Imbrian Era starts.
• 3,850 Ma: Greenland apatite shows evidence of ¹²C enrichment, characteristic of the presence of photosynthetic life.
• 3,850 Ma: First evidence of life: Akilia island graphite off Western Greenland contains evidence of kerogen, of a type consistent with photosynthesis.

Archaean Eon

Main article: Archaean

Eoarchaean

• 3,800 Ma: Archean Eon and Eoarchean Era start.
• 3,800 Ma: Oldest banded iron formations found.

Paleoarchaean

• 3,600 Ma: Paleoarchean Era starts. Possible assembly of the Vaalbara supercontinent
• 3,500 Ma: Fossils resembling cyanobacteria, found at Warrawoona, Western Australia.
• 3,460 Ma: Fossils of bacteria in chert.
• 3,300 Ma: Onset of compressional tectonics

Mesoarchaean

• 3,200 Ma: Mesoarchean Era starts.
• 3,200–2600 Ma: Assembly of the Ur supercontinent to cover between 12–16% of the current continental crust.
• 2,900 Ma: Assembly of the Kenorland supercontinent, based upon the core of the Baltic shield, formed at 3100 Ma.

Neoarchaean

• 2,800 Ma: Neoarchean Era starts. Breakup of the Vaalbara supercontinent
• 2,736 Ma: Formation of the Temagami greenstone belt in Temagami, Ontario, Canada
• 2,705 Ma: Major komatiite eruption, possibly global
• 2,700 Ma: Biomarkers of cyanobacteria discovered, together with steranes (sterols of cholesterol), associated with films of eukaryotes, in shales located beneath banded iron formation hematite beds, in Hamersley Range, Western Australia Skewed sulfur isotope ratios found in pyrites shows a small rise in oxygen concentration in the atmosphere
• 2,600 Ma: Oldest known giant carbonate platform

Proterozoic Eon

Main article: Proterozoic

Paleoproterozoic

Main article: Paleoproterozoic

• 2,500 Ma: Proterozoic Eon, Paleoproterozoic Era, and Siderian Period start. Banded iron formations form during this period. Earth's atmosphere starts to become oxygenic. Assembly of Arctica out of the Canadian Laurentian Shield and Siberian craton.
• 2,400 Ma: Huronian glaciation starts, probably from oxidation of earlier methane greenhouse gas produced by burial of organic sediments of photosynthesizers. First cyanobacteria.
• 2,300 Ma: Rhyacian period starts.
• 2,200–1800 Ma: Continental Red Beds found, produced by iron in weathered sandstone being exposed to oxygen.
• 2,200 Ma: Iron content of ancient fossil soils shows an oxygen built up to 5–18% of current levels
• 2,100 Ma: Huronian glaciation ends. Earliest known eukaryote fossils found. Earliest multicellular organisms (Francevillian Group Fossil)
• 2,050 Ma: Orosirian Period starts. Significant orogeny in most continents.
• 2,023 Ma: Vredefort impact structure forms.
• 2,000 Ma: The lesser supercontinent Atlantica forms. The Oklo natural nuclear reactor of Gabon produced by uranium-precipitant bacteria. First acritarchs.
• 1,850 Ma: Sudbury impact structure. Penokean orogeny. First eukaryotes.
• 1,800 Ma: Statherian Period starts. Supercontinent Columbia forms, one of whose fragments being Nena. Oldest ergs develop on several cratons

Mesoproterozoic

Main article: Mesoproterozoic

• 1,600 Ma: Mesoproterozoic Era and Calymmian Period start. Platform covers expand.
• 1,500 Ma: Supercontinent Columbia breaks up. First structurally complex eukaryotes.
• 1,400 Ma: Ectasian Period starts. Platform covers expand. Stromatolite diversity increases.
• 1,300 Ma: Grenville orogeny starts.
• 1,200 Ma: Red alga Bangiomorpha pubescens, first known sexually reproducing organism. Stenian Period starts, during which supercontinent Rodinia comes together.
• 1,100 Ma: First dinoflagellate.

Neoproterozoic

Main article: Neoproterozoic

• 1,000 Ma: Grenville orogeny ends. Neoproterozoic Era and Tonian Period starts. First radiation of acritarchs. Rodinia starts to break up. First vaucherian algae.
• 850 Ma: Cryogenian Period starts, during which Earth freezes over (Snowball Earth or Slushball Earth) at least 3 times.
• 750 Ma: Sturtian glaciation starts. Rodinia splits. Beginning of a possible Snowball Earth ice age. First protozoa.
• 700 Ma: Worm impressions in China.
• 685 Ma: Varanger glaciation begins.
• 635 Ma: Varanger glaciation ends.
• 635 Ma: Ediacaran period begins.
• 600 Ma: Pan-African orogeny. Supercontinent Pannotia forms.
• 575 Ma: First Ediacaran-type fossils.
• 560 Ma: Trace fossils, e.g., worm burrows, and small bilaterally symmetrical animals. Earliest arthropods. Earliest fungi.
• 555 Ma: The first possible mollusk Kimberella appears.
• 550 Ma: First possible comb-jellies, sponges, corals, and anemones.
• 544 Ma: The small shelly fauna first appears.

Phanerozoic Eon

Main article: Phanerozoic

Paleozoic

Main article: Paleozoic

• 542 Ma: beginning of the Cambrian period, the Paleozoic Era and the Phanerozoic (current) Eon. End of the Ediacaran Period, the Proterozoic Eon and the Precambrian Supereon. Time since the Cambrian explosion the emergence of most forms of complex life, including vertebrates (fish), arthropods, echinoderms and molluscs. Pannotia breaks up into several smaller continents: Laurentia, Baltica and Gondwana.
• 530 Ma: Possible early land animals.
• 525 Ma: First graptolites.
• 510 Ma: First cephalopods and chitons.
• 505 Ma: Fossilization of the Burgess Shale.
• 500 Ma: Beginning of the Ordovician and the end of the Cambrian period.
• 485 Ma: First jawless fishes.
• 450 Ma: Plants and arthropods colonize the land. Sharks evolve.
• 440 Ma: First agnathan fish.
• 435 Ma: Beginning of the Silurian and the end of the Ordovician period.
• 420 Ma: First creature took a breath of air. First ray-finned fish and land scorpions.
• 410 Ma: First toothed fish and nautiloids.
• 400 Ma: Beginning of the Devonian and end of the Silurian period. First insects.
• 395 Ma: First of many modern groups, including tetrapods.
• 360 Ma: First crabs and ferns.
• 350 Ma: First large sharks, ratfish and hagfish.
• 340 Ma: Beginning of the Carboniferous and the end of Devonian period. Amphibians diversify.
• 330 Ma: First amniotes evolve.
• 320 Ma: First synapsids evolve.
• 315 Ma: The evolution of the first reptiles.
• 305 Ma: First diapsids evolve.
• 280 Ma: End of Carboniferous and beginning of Permian Period. By this time, all continents have fused into the supercontinent of Pangaea. Beetles evolve. Seed plants and conifers diversify along with temnospondyls and pelycosaurs.
• 275 Ma: First therapsids evolve.
• 251.4 Ma: Permian mass extinction. End of Permian Period and of the Palaeozoic Era. Beginning of Triassic Period, the Mesozoic era and of the age of the dinosaurs.

Mesozoic

Main article: Mesozoic

• 251.4 Ma: Mesozoic era and Triassic period begin. Mesozoic Marine Revolution begins.
• 245 Ma: First ichthyosaurs.
• 240 Ma: Cynodonts and rhynchosaurs diversify.
• 225 Ma: First dinosaurs and teleosti evolve.
• 220 Ma: First crocodilians and flies.
• 215 Ma: First turtles. Long-necked sauropod dinosaurs and Coelophysis, one of the earliest theropod dinosaurs, evolve. First mammals.
• 195 Ma: end of Triassic and beginning of Jurassic Period. The largest dinosaurs, such as Diplodocus and Brachiosaurus evolve during this time, as do the carnosaurs; large, bipedal predatory dinosaurs such as Allosaurus. First specialized pterosaurs and sauropods. Ornithischians diversify.
• 190 Ma: Pliosaurs evolve, along with many groups of primitive sea invertebrates.
• 180 Ma: Pangaea splits into two major continents: Laurasia in the north and Gondwana in the south.
• 176 Ma: First stegosaurs.
• 170 Ma: First salamanders and newts evolve. Cynodonts go extinct.
• 165 Ma: First stingrays.
• 161 Ma: First ceratopsians.
• 155 Ma: First birds and triconodonts. Stegosaurs and theropods diversify.
• 135 Ma: End of Jurassic and beginning of Cretaceous Period.
• 130 Ma: Laurasia and Gondwana begin to split apart as the Atlantic Ocean forms. First flowering plants.
• 115 Ma: First monotremes.
• 110 Ma: First hesperornithes.
• 106 Ma: Spinosaurus evolves.
• 100 Ma: First bees.
• 90 Ma: the Indian subcontinent splits from Gondwana, becoming an island continent. Ichthyosaurs go extinct. Snakes and ticks evolve.
• 80 Ma: Australia splits from Antarctica. First ants.
• 70 Ma: Multituberculates diversify.
• 68 Ma: Tyrannosaurus Rex evolves.
• 65 Ma: Cretaceous-Tertiary extinction event at the end of the Cretaceous period marks the end of the Mesozoic era and the age of the dinosaurs; start of the Paleogene period and the current Cenozoic era.

Cenozoic

Main article: Cenozoic

• 63 Ma: First creodonts.
• 60 Ma: Evolution of the first primates and miacids. Flightless birds diversify.
• 56 Ma: Gastornis evolves.
• 55 Ma: the island of the Indian subcontinent collides with Asia, thrusting up the Himalayas and the Tibetan Plateau. Many modern bird groups appear. First whale ancestors. First rodents, lagomorphs, armadillos, sirenians, proboscideans, perissodactyls, artiodactyls, and mako sharks. Angiosperms diversify.
• 52 Ma: First bats.
• 50 Ma: Africa collides with Eurasia, closing the Tethys Sea. Divergence of cat and dog ancestors. Primates diversify. Brontotheres, tapirs, rhinos, and camels evolve.
• 49 Ma: Whales return to the water.
• 40 Ma: Age of the Catarrhini parvorder; first canines evolve. Lepidopteran insects become recognizable. Gastornis goes extinct. Basilosaurus evolves.
• 37 Ma: First Nimravids.
• 36 Ma: End of Eocene, start of Oligocene epoch.
• 35 Ma: Grasslands first appear. Glyptodonts, ground sloths, peccaries, dogs, eagles, and hawks evolve.
• 34 Ma: Cats evolve.
• 33 Ma: First thylacinid marsupials evolve.
• 30 Ma: Brontotheres go extinct. Pigs evolve. South America separates from Antarctica, becoming an island continent.
• 28 Ma: Paraceratherium evolves.
• 26 Ma: Emergence of the first true elephants.
• 25 Ma: First deer.
• 24 Ma: Neogene period and Miocene epoch begin
• 20 Ma: Giraffes and giant anteaters evolve.
• 18-12 Ma: estimated age of the Hominidae/Hylobatidae (great apes vs. gibbons) split.
• 15 Ma: First mastodons, bovids, and kangaroos. Australian megafauna diversify.
• 10 Ma: Insects diversify. First large horses.
• 6.5 Ma: First members of the Hominini tribe.
• 6 Ma: Australopithecines diversify.
• 5.4-6.3 Ma: Estimated age of the Homo/Pan (human vs. chimpanzee) split.
• 5.5 Ma: Appearance of the genus Ardipithecus
• 5 Ma: Pliocene epoch begins. First tree sloths and hippopotami. First large vultures. Nimravids go extinct.
• 4.8 Ma: The mammoth appears.
• 4.5 Ma: appearance of the genus Australopithecus
• 3 Ma: Isthmus of Panama joins North and South America. Great American Interchange.
• 2.7 Ma: Paranthropus evolve.
• 2.6 Ma: current ice age begins
• 2.5 Ma: start of the Pleistocene epoch, the Stone Age and the current Quaternary period; emergence of the genus Homo. Smilodon, the best known of the sabre-toothed cats, appears.
• 1.7 Ma: Australopithecines go extinct.
• 1.5 Ma: earliest possible evidence of the controlled use of fire by Homo erectus
• 1.2 Ma: Homo antecessor evolves. Paranthropus dies out.
• 0.79 Ma: earliest demonstrable evidence of the controlled use of fire by Homo erectus
• 0.7 Ma: last reversal of the earth's magnetic field
• 0.6 Ma: Homo heidelbergensis evolves.
• 0.5 Ma: colonisation of Eurasia by Homo erectus
• 0.35 Ma: Neanderthals evolve.
• 0.3 Ma: Approximate age of Canis lupus. Middle Stone Age begins in Africa. Gigantopithecus evolves.
• 0.2 Ma: Middle Paleolithic begins. Appearance of Homo sapiens in Africa

For later events, see Timeline of human prehistory.

Etymology of period names

Period	Started	Root word	Meaning	Reason for name
Siderian	2500 Ma	Greek sidēros	iron	ref. the banded iron formations
Rhyacian	2300 Ma	Gk. rhyax	lava flow	much lava flowed
Orosirian	2050 Ma	Gk. oroseira	mountain range	much orogeny in this period's latter half
Statherian	1800 Ma	Gk. statheros	steady	continents became stable cratons
Calymmian	1600 Ma	Gk. calymma	cover	platform covers developed or expanded
Ectasian	1400 Ma	Gk. ectasis	stretch	platform covers expanded
Stenian	1200 Ma	Gk. stenos	narrow	much orogeny, which survives as narrow metamorphic belts
Tonian	1000 Ma	Gk. tonos	stretch	The continental crust stretched as Rodinia broke up
Cryogenian	850 Ma	Gk. cryogenicos	cold-making	In this period all the Earth froze over
Ediacaran	635 Ma	Ediacara Hills		place in Australia where the Ediacaran biota fossils were found
Cambrian	542 Ma	Latin Cambria	Wales	ref. to the place in Great Britain where Cambrian rocks are best exposed
Ordovician	488 Ma	Celtic Ordovices		Tribe in north Wales, where the rocks were first identified
Silurian	444 Ma	Ctc. Silures		Tribe in south Wales, where the rocks were first identified
Devonian	416 Ma	Devon		County in England in which rocks from this period were first identified
Carboniferous	359 Ma	Lt. carbo	coal	Global coal beds were laid in this period
Permian	299 Ma	Perm Krai		Region in Russia where rocks from this period were first identified
Triassic	250 Ma	Lt. trias	triad	In Germany this period forms three distinct layers
Jurassic	200 Ma	Jura Mountains		Mountain range in the Alps in which rocks from this period were first identified
Cretaceous	146 Ma	Lt. creta	chalk	More chalk formed in this period than any other
Paleogene	65 Ma	Gk. palaiogenos	"ancient born"
Neogene	23 Ma	Gk. neogenos	"new born"
Quaternary	2.6 Ma	Lt. quaternarius	"fourth"	This was initially deemed the "fourth" period after the now-obsolete "primary", "secondary" and "tertiary" periods.

See also

• Timeline of the far future
• Detailed logarithmic timeline
• Terasecond and longer