List of earliest taxonomically identified lifeforms

This is a list of the earliest taxonomically identified lifeforms.
==Precambrian==
===Hadeon Eon (4567.30 ± 0.16 - 4031 ± 3 Mya)===
4567 - 4404 Mya	Chaotian Era (proposed)
4519 - 4477 Mya	A molecular clock model suggests that the Last Universal Common Ancestor (LUCA) may have lived around this time.Betts, Holly C.; Putick, Mark N.; Clark, James W.; Williams, Tom A.; Donoghue, Philip C.J.; Pisani, Davide (20 August 2018). "Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin". Nature. 2 (10): 1556–1562.
4500 Mya 	Some computer models suggest life began as early as 4.5 billion years ago.Betts, Holly C.; Putick, Mark N.; Clark, James W.; Williams, Tom A.; Donoghue, Philip C.J.; Pisani, Davide (20 August 2018). "Integrated genomic and fossil evidence illuminates life's early evolution and eukaryote origin". Nature. 2 (10): 1556–1562.
4404 - 4030 Mya	Zirconian Era (proposed)
4280 Mya 	Claims of the earliest life using fossilized microorganisms are from hydrothermal vent precipitates from an ancient sea-bed in the Nuvvuagittuq Belt of Quebec, Canada. These may be as old as 4.28 Ga, which would make it the oldest evidence of life on Earth, suggesting "an almost instantaneous emergence of life" after ocean formation 4.41 billion years ago.Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; slack, John F.; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T. S. (2 March 2017). "Evidence for early life in Earth's oldest hydrothermal vent precipitates" (PDF). Nature. 543 (7643): 60–64. However, these findings may be better explained by abiotic processes: for example, silica-rich waters,García-Ruiz, Juan Manuel; Nakouzi, Elias; Kotopoulou, Electra; Tamborrino, Leonardo; Steinbock, Oliver (2017-03-03). "Biomimetic mineral self-organization from silica-rich spring waters". Science Advances. 3 (3) "chemical gardens",McMahon, Sean (2019-12-04). "Earth's earliest and deepest purported fossils may be iron-mineralized chemical gardens". Proceedings of the Royal Society B: Biological Sciences. 286 (1916) circulating hydrothermal fluids,Johannessen, Karen C.; McLoughlin, Nicola; Vullum, Per Erik; Thorseth, Ingunn H. (January 2020). "On the biogenicity of Fe-oxyhydroxide filaments in silicified low-temperature hydrothermal deposits: Implications for the identification of Fe-oxidizing bacteria in the rock record". Geobiology. 18 (1): 31–53. and volcanic ejectaWacey, David; Saunders, Martin; Kong, Charlie (April 2018). "Remarkably preserved tephra from the 3430 Ma Strelley Pool Formation, Western Australia: Implications for the interpretation of Precambrian microfossils". Earth and Planetary Science Letters. 487: 33–43. can produce morphologies similar to those presented in Nuvvuagittuq.
4250 Mya 	Possible earliest evidence for life, based on unusually high amounts of light isotopes of carbon, a common sign of life, found in Earth's oldest mineral deposits located in the Jack Hills of Western Australia.Courtland, Rachel (July 2, 2008). "Did newborn Earth harbour life?". New Scientist.
4100 Mya 	Possible. but disputed, "remains of biotic life" based on carbon isotope ratios on graphite inclusions from the Jack Hills zircons.Bell, Elizabeth A.; Boehnike, Patrick; Harrison, T. Mark; et al. (19 October 2015). "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon".
===Archean Eon (4031 ± 3 – 2500 Mya)===
 	
4031 - 3600 Mya	Eoarchean Era
3900 Mya 	Cells resembling prokaryotes appear.Woese, Carl; Gogarten, J. Peter (October 21, 1999). "When did eukaryotic cells (cells with nuclei and other internal organelles) first evolve? What do we know about how they evolved from earlier life-forms?". Scientific American. These first organisms are believed to have been chemoautotrophs, using carbon dioxide as a carbon source and oxidizing inorganic materials to extract energy.
3850 Mya 	Greenland apatite shows evidence of 12C enrichment, which may suggest the presence of photosynthetic life.Mojzis, S, et al. (1996), "Evidence for Life on Earth before 3800 million years ago", (Nature, 384)
 	Akilia Island graphite off Western Greenland contains evidence of kerogen, of a type possibly consistent with photosynthesis. (uncited)
3800 Mya 	Possible lifetime of LUCA, shortly before split between Bacteria and Archaea.Glansdorff, Nicolas; Ying Xu; Labedan, Bernard (July 9, 2008). "The Last Universal Common Ancestor: emergence, constitution and genetic legacy of an elusive forerunner". Biology Direct. 3: 29.
3770 Mya 	Possible earliest physical evidence of life consisting of microbialites found in the Nuvvuagittuq Greenstone Belt of Northern Quebec, in banded iron formation rocks at least 3.77 and possibly as old as 4.32 Gya.Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; et al. (1 March 2017). "Evidence for early life in Earth's oldest hydrothermal vent precipitates". Nature. 543 (7643): 60–64.
3700 Mya 	Possible earliest evidence for life in graphite of biogenic origin found in metasedimentary rocks in Western Greenland.Ohtomo Y, Kakegawa T, Ishida A, Nagase T, Rosing MT (8 December 2013). "Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks". Nature Geoscience. 7 (1): 25–28.
 	Evidence of early life in rocks from Akilia Island, near the Isua supracrustal belt in southwestern Greenland, dating to 3.7 Gya, have shown biogenic carbon isotopes.Davies, Paul (1999). The Fifth Miracle: The Search for the Origin of Life. London: Penguin Books. ISBN 978-0-14-028226-9.
 	In other parts of the Isua supracrustal belt, graphite inclusions trapped within garnet crystals are connected to the other elements of life: oxygen, nitrogen, and possibly phosphorus in the form of phosphate, providing further evidence for life.Hassenkam, T.; Andersson, M. P.; Dalby, K. N.; Mackenzie, D. M. A.; Rosing, M.T. (2017). "Elements of Eoarchean life trapped in mineral inclusions". Nature. 548 (7665): 78–81.
 	Disputed reports of stromatolites from the 3.7 Ga Isua metasediments that show convex-up, conical, and domical morphologies.Nutman, Allen P.; Bennett, Vickie C.; Friend, Clark R. L.; Van Kranendonk, Martin J.; Chivas, Allan R. (2016-08-31). "Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures". Nature. 537 (7621): 535–538. Allwood, Abigail C. (22 September 2016). "Evidence of life in Earth's oldest rocks". Nature. 537 (7621): 500–5021. Further mineralogical analysis disagrees with the initial findings of internal convex-up laminae, a critical criteria for stromatolite identification, suggesting that the structures may be deformation features (i.e. boudins) caused by extensional tectonics in the Isua Supracrustal Belt.Zawaski, Mike J.; Kelly, Nigel M.; Orlandini, Omero Felipe; Nichols, Claire I. O.; Allwood, Abigail C.; Mojzsis, Stephen J. (2020-09-01). "Reappraisal of purported ca. 3.7 Ga stromatolites from the Isua Supracrustal Belt (West Greenland) from detailed chemical and structural analysis". Earth and Planetary Science Letters. 545. Wei-Haas, Maya (17 October 2018). "'World's oldest fossils' may just be pretty rocks – Analysis of 3.7-billion-year-old outcrops has reignited controversy over when life on Earth began". National Geographic.
3600 - 3200 Mya	Paleoarchean Era
3500 Mya 	The Pilbara region of Western Australia contains the Dresser Formation with rocks 3.48 Gya old, including layered structures of stromatolites.Baumgartner, Rafael; Van Kranendonk, Martin; Wacey, David; et al. (2019). "Nano−porous pyrite and organic matter in 3.5-billion-year-old stromatolites record primordial life" (PDF). Geology. 47 (11): 1039–1043.
3500 Mya 	Other possible lifetime of LUCA, shortly before split between Bacteria and Archaea. (uncited)
 	Fossils resembling cyanobacteria, found at Warrawoona, Western Australia. (uncited)
 	Split between Bacteria and Archaea occurs as "tree of life" begins branching out. (uncited)
 	Varieties of Eubacteria begin to radiate globally. (uncited)
 	Bacteria develop primitive photosynthesis, which at first did not produce oxygen.Olson, John M. (May 2006). "Photosynthesis in the Archean era". Photosynthesis Research. 88 (2): 109–117. These organisms exploit a proton gradient to generate adenosine triphosphate (ATP), a mechanism used by virtually all subsequent organisms.Romano, Antonio H.; Conway, Tyrrell (July–September 1996). "Evolution of carbohydrate metabolic pathways". Research in Microbiology. 147 (6–7): 448–455.
3480 Mya 	Possible first appearance of photosynthetic organisms.Caredona, Tanai (6 March 2018). "Early Archean origin of heterodimeric Photosystem I". Heliyon. 4 (3)
 	Earliest direct known life on land may be stromatolites (microbial mats formed in shallow waters by cyanobacteria) found in sandstone discovered in the Pilbara region of Western Australia.Noffke N, Christian D, Wacey D, Hazen RM (December 2013). "Microbially induced sedimentary structures recording an ancient ecosystem in the ca. 3.48 billion-year-old Dresser Formation, Pilbara, Western Australia". Astrobiology. 13 (12): 1103–1124. Sulfur isotopes from barite veins in the stromatolites also favor a biologic origin.Philippot, Pascal; Van Zuilen, Mark; Lepot, Kevin; Thomazo, Christophe; Farquhar, James; Van Kranendonk, Martin J. (2007-09-14). "Early Archaean Microorganisms Preferred Elemental Sulfur, Not Sulfate". Science. 317 (5844): 1534–1537. However, abiotic explanations for these fossils cannot be fully discarded due to their hydrothermal depositional environment and debated geochemical evidence.Lollar, Barbara Sherwood; McCollom, Thomas M. (December 2006). "Biosignatures and abiotic constraints on early life". Nature. 444 (7121): E18, discussion E18-9.
 	Metasedimentary rocks from the Dresser Formation, which experienced less metamorphism than the sequences in Greenland, contain possible preserved geochemical evidence of life.Van Kranendonk, Martin J.; Djokic, Tara; Poole, Greg; Tadbiri, Sahand; Steller, Luke; Baumgartner, Raphael (2019), "Depositional Setting of the Fossiliferous, c.3480 Ma Dresser Formation, Pilbara Craton", Earth's Oldest Rocks, Elsevier, pp. 985–1006
 	Carbon isotopes as well as sulfur isotopes found in barite from the Dresser Formation, which are fractionated by microbial metabolisms during sulfate reductionSim, Min Sub; Woo, Dong Kyun; Kim, Bokyung; Jeong, Hyeonjeong; Joo, Young Ji; Hong, Yeon Woo; Choi, Jy Young (2023-03-15). "What Controls the Sulfur Isotope Fractionation during Dissimilatory Sulfate Reduction?". ACS Environmental Au. 3 (2): 76–86., are consistent with biological processes; the Formation may hosts microfossils of prokaryotic filaments in silica veins, the earliest fossil evidence of life on Earth.Ueno, Yuichiro; Yamada, Keita; Yoshida, Naohiro; Maruyama, Shigenori; Isozaki, Yukio (March 2006). "Evidence from fluid inclusions for microbial methanogenesis in the early Archaean era". Nature. 440 (7083): 516–519. Wacey, David; Noffke, Nora; Cliff, John; Barley, Mark E.; Farquhar, James (September 2015). "Micro-scale quadruple sulfur isotope analysis of pyrite from the ∼3480Ma Dresser Formation: New insights into sulfur cycling on the early Earth". Precambrian Research. 258: 24–35. However, the Dresser formation was deposited in an active volcanic and hydrothermal environment,Wacey, David; Noffke, Nora; Saunders, Martin; Guagliardo, Paul; Pyle, David M. (May 2018). "Volcanogenic Pseudo-Fossils from the ∼3.48 Ga Dresser Formation, Pilbara, Western Australia". Astrobiology. 18 (5): 539–555. and abiotic processes could still be responsible for these fractionations.Lollar, Barbara Sherwood; McCollom, Thomas M. (December 2006). "Biosignatures and abiotic constraints on early life". Nature. 444 (7121): E18, discussion E18-9.
 	Possible first appearance of stromatolitic organisms that grow at interfaces between different types of material, mostly on submerged or moist surfaces. (uncited)
3470 Mya 	Evidence for early life found in baryte discovered in the Warrawoona Group of Western Australia.Shen Y, Buick R, Canfield DE (March 2001). "Isotopic evidence for microbial sulphate reduction in the early Archaean era". Nature. 410 (6824): 77–81
3465 Mya 	Various microfossils of microorganisms have been found in 3.4 Ga rocks, including 3.465-billion-year-old Apex chert rocks from the same Australian craton region,Schopf, J. William; Kitajima, Kouki; Spicuzza, Michael J.; Kudryavtsev, Anatolly B.; Valley, John W. (2017). "SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions". PNAS. 115 (1): 53–58. although the validity of these findings has been contested.Brasier, Martin D.; Green, Owen R.; Lindsay, John F.; McLoughlin, Nicola; Steele, Andrew; Stoakes, Cris (2005-10-21). "Critical testing of Earth's oldest putative fossil assemblage from the ~3.5Ga Apex chert, Chinaman Creek, Western Australia". Precambrian Research. 140 (1): 55–102. Pinti, Daniele L.; Mineau, Raymond; Clement, Valentin (2009-08-02). "Hydrothermal alteration and microfossil artefacts of the 3,465-million-year-old Apex chert". Nature Geoscience. 2 (9): 640–643.
3460 Mya 	Possible fossils of bacteria found in chert. (uncited)
 	Stratiform stromatolites evidence at the Hooggenoeg Formation of the Onverwacht Group in Barberton, South Africa.Hickman-Lewis, Keyron; Westall, Frances; Cavalazzi, Barbara (2019), "Traces of Early Life From the Barberton Greenstone Belt, South Africa", Earth's Oldest Rocks, Elsevier, pp. 1029–1058
3430 Mya 	The Strelley Pool Formation in Western Australia hosts stromatolites that demonstrate vertical and horizontal changes that may demonstrate microbial communities responding to transient environmental conditions.Allwood, Abigail C.; Grotzinger, John P.; Knoll, Andrew H.; Burch, Ian W.; Anderson, Mark S.; Coleman, Max L.; Kanik, Isik (2009-06-16). "Controls on development and diversity of Early Archean stromatolites". Proceedings of the National Academy of Sciences. 106 (24): 9548–9555. Thus, it is likely anoxygenic or oxygenic photosynthesis has been occurring since at least this time.Duda, Jan-Peter; Kranendonk, Martin J. Van; Thiel, Volker; Ionescu, Danny; Strauss, Harald; Schäfer, Nadine; Reitner, Joachim (2016-01-25). "A Rare Glimpse of Paleoarchean Life: Geobiology of an Exceptionally Preserved Microbial Mat Facies from the 3.4 Ga Strelley Pool Formation, Western Australia". PLOS ONE. 11 (1),
 	A diverse set of microfossil morphologies have been found in the Strelley Pool Formation including spheroid, lenticular, and film-like microstructures.Sugitani, K.; Mimura, K.; Takeuchi, M.; Lepot, K.; Ito, S.; Javaux, E. J. (November 2015). "Early evolution of large micro-organisms with cytological complexity revealed by microanalyses of 3.4 Ga organic-walled microfossils". Geobiology. 13 (6): 507–521. Their biogenicity are strengthened by their observed chemical preservation; the early lithification of these structures allowed important chemical tracers, such as the carbon-to-nitrogen ratio, to be retained at levels higher than is typical in older, metamorphosed rock units.Alleon, J.; Bernard, S.; Le Guillou, C.; Beyssac, O.; Sugitani, K.; Robert, F. (August 2018). "Chemical nature of the 3.4 Ga Strelley Pool microfossils". Geochemical Perspectives Letters: 37–42.
3420 Mya 	"Putative filamentous microfossils" possibly of methanogens and/or methanotrophs that lived in "a paleo-subseafloor hydrothermal vein system" have been possibly identified from Barberton, South Africa.Cavalazzi, Barbara; et al. (14 July 2021). "Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment". Science Advances. 7 (9)
3416/3334 Mya 	The Kromberg Formation, near the top of the Onverwacht Group which itself is a part of the Barberton Greenstone Belt, South Africa, contains evidence of microbial life reproducing via multiple fission and binary fission.Kaźmierczak, Józef; Kremer, Barbara (1 September 2019). "Pattern of cell division in ~3.4 Ga-old microbes from South Africa". Precambrian Research. 331: 1–9.
3400 Mya 	Eleven taxa of prokaryotes are preserved in the Apex Chert of the Pilbara craton in Western Australia. (uncited)
 	The Strelley Pool Chert, also located in the Pilbara Craton, contains stromatolites that may have been created by bacteria 3.4 billion years ago. However, it is possible that these stromatolies are abiogenic and were actually formed through evaporitic precipitation then deposited on the sea floor.van Kranendonk, Martin J. (2007). "Chapter 7.2 A review of the evidence for putative Paleoarchean life in the Pilbara craton, Western Australia". In van Kranendonk, Martin J.; Smithies, R. Hugh; Bennett, Vickie C. (eds.). Developments in Precambrian Geology. Earth's Oldest Rocks. Vol. 15. Elsevier. pp. 855–877.
 	In the Pilbara region of Western Australia, compelling evidence of early life was found in pyrite-bearing sandstone in a fossilized beach, with rounded tubular cells that oxidized sulfur by photosynthesis in the absence of oxygen.Wacey, David; Kilburn, Matt R.; Saunders, Martin; et al. (October 2011). "Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia". Nature Geoscience. 4 (10): 698–702.
3330 Mya 	Stratiform stromatolites evidence at the Mendon Formations of the Onverwacht Group in Barberton, South Africa. Hofmann, H. J. (2000), Riding, Robert E.; Awramik, Stanley M. (eds.), "Archean Stromatolites as Microbial Archives", Microbial Sediments, Berlin, Heidelberg: Springer, pp. 315–327
3226 Mya 	The Buck Reef chert and the Josefsdal chert, two rock formations in the Barberton Greenstone Belt of South Africa, both contain microbial mats with fossilized bacteria from the Paleoarchean era.Homann, Martin (2019). "Earliest life on Earth: Evidence from the Barberton Greenstone Belt, South Africa" (PDF). Earth-Science Reviews. 196
3220 Mya 	Fossilized microbes from terrestrial microbial mats (earliest known life on land) possibly identified in South Africa.Homann, Martin; Sansjofre, Pierre; Van Zuilen, Mark; Heubeck, Christoph; Gong, Jian; Killingsworth, Bryan; Foster, Ian S.; Airo, Alessandro; Van Kranendonk, Martin J.; Ader, Magali; Lalonde, Stefan V. (23 July 2018). "Microbial life and biogeochemical cycling on land 3,220 million years ago". Nature Geoscience. 11 (9): 665–671
3200 - 2800 Mya	Mesoarchean Era
3200 Mya 	Onverwacht series in South Africa contains some of the oldest microfossils, mostly spheroidal and carbonaceous alga-like bodies. (uncited)
3100 Mya 	Fig Tree Formation: second round of fossilizations including Archaeosphaeroides barbertonensis and extinct genus Eobacterium. (uncited)
3000 Mya 	Photosynthesizing cyanobacteria using water as a reducing agent and producing oxygen as a waste product.Buick, Roger (August 27, 2008). "When did oxygenic photosynthesis evolve?". Philosophical Transactions of the Royal Society B. 363 (1504): 2731–2743.
 	Free oxygen initially oxidizes dissolved iron in the oceans, creating iron ore. Oxygen concentration in the atmosphere slowly rises, poisoning many bacteria and eventually triggering the Great Oxygenation Event.
2800 - 2500 Mya	Neoarchean Era
2800 Mya 	Evidence for microbial life on land in the form of organic matter-rich paleosols, ephemeral ponds and alluvial sequences, some bearing microfossils.Beraldi-Campesi, Hugo (February 23, 2013). "Early life on land and the first terrestrial ecosystems" (PDF). Ecological Processes. 2 (1): 4.
2700 Mya 	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.Brocks et al. (1999), "Archaean molecular fossils and the early rise of eukaryotes", (Science 285) Lipids are commonly used in geologic studies to find evidence of oxygenic photosynthesis. However, the age of these biomarkers and whether their deposition was synchronous with their host rocks has been debated.Rasmussen, Birger; Fletcher, Ian R.; Brocks, Jochen J.; Kilburn, Matt R. (October 2008). "Reassessing the first appearance of eukaryotes and cyanobacteria". Nature. 455 (7216): 1101–1104. French, Katherine L.; Hallmann, Christian; Hope, Janet M.; Schoon, Petra L.; Zumberge, J. Alex; et al. (2015-04-27). "Reappraisal of hydrocarbon biomarkers in Archean rocks". Proceedings of the National Academy of Sciences. 112 (19): 5915–5920.
 	Skewed sulfur isotope ratios found in pyrites show a small rise in oxygen concentration in the atmosphere.Canfield, D (1999), "A Breath of Fresh Air" (Nature 400)
 	Stromatolites of Bulawayo series in Zimbabwe, possibly first verified reef community on Earth. (uncited)
2670 Mya 	Fossilized lipids reported from the Kaapvaal Craton in South Africa.Waldbauer, Jacob R.; Sherman, Laura S.; Sumner, Dawn Y.; Summons, Roger E. (2009-03-01). "Late Archean molecular fossils from the Transvaal Supergroup record the antiquity of microbial diversity and aerobiosis". Precambrian Research. Initial investigations of a Neoarchean shelf margin–basin transition (Transvaal Supergroup, South Africa). 169 (1): 28–47. However, further work showed that the lipids were contaminants.
===Proterozoic Eon (2500 - 541 Mya)===
 	
2500 - 1600 Mya	Paleoproterozoic Era
2500 - 2300 Mya	Siderian Period
2500 Mya 	Great Oxidation Event led by cyanobacteria's oxygenic photosynthesis; various forms of Archaea and anoxic bacteria become extinct in first great extinction event on Earth.
2400 Mya 	Huronian glaciation starts, probably from oxidation of earlier methane greenhouse gas produced by burial of organic sediments of photosynthesizers.
2300 - 2050 Mya	Rhyacian Period
2300 Mya 	A molecular clock analysis suggests the emergence of eukaryotic sterol biosynthesis around this time.Gold DA, Caron A, Fournier GP, Summons RE (March 2017). "Paleoproterozoic sterol biosynthesis and the rise of oxygen". Nature. 543 (7645): 420–423. However, the nature of steranes as eukaryotic biomarkers is further complicated by the production of sterols by some bacteria.Hoshino Y, Gaucher EA (June 2021). "Evolution of bacterial steroid biosynthesis and its impact on eukaryogenesis". Proceedings of the National Academy of Sciences of the United States of America. 118 (25).
2200 Mya 	The First Eukaryotic Common Ancestor (FECA) may have lived around this time.
In the syntrophic model, it first gained mitochondria, then membranes, then a nucleus. In the phagotrophic model, it gained a nucleus, then membranes, then mitochondria. In a more complex process, it gained all three in short order, then other capabilities. Whatever happened, many lineages must have been created, but later the LECA either out-competed or came together with the other lineages to form a single point of origin for the eukaryotes.Koumandou, V. Lila; Wickstead, Bill; Ginger, Michael L.; van der Giezen, Mark; Dacks, Joel B.; Field, Mark C. (2013). "Molecular paleontology and complexity in the last eukaryotic common ancestor". Critical Reviews in Biochemistry and Molecular Biology. 48 (4): 373–396.
 	From around this time, Diskagma represents a genus of problematic fossil from a Paleoproterozoic paleosol from South Africa. It's significant as the oldest likely eukaryote and the earliest evidence for megascopic life on land.Retallack, G.J.; Krull, E.S.; Thackray, G.D.; Parkinson, D. (2013). "Problematic urn-shaped fossils from a Paleoproterozoic (2.2 Ga) paleosol in South Africa". Precambrian Research. 235: 71–87.
 	Diskagma buttonii is a small fossil less than 1mm in length found within the surface horizon of a vertisol paleosol above the Hekpoort Basalt.
2100 Mya 	Earliest known eukaryote fossils found.
 	First attestation of the controversial multicellular Francevillian biota, known from the Francevillian B Formation in Gabon.El Albani, Abderrazak; Bengtson, Stefan; Canfield, Donald E.; Riboulleau, Armelle; Rollion Bard, Claire; Macchiarelli, Roberto; et al. (2014). "The 2.1 Ga Old Francevillian Biota: Biogenicity, Taphonomy and Biodiversity". PLOS ONE. 9 (6) The structures have been postulated by some authors to be evidence of the earliest form of multicellular life, and of eukaryotes.El Albani, Abderrazak (2023). "A search for life in Palaeoproterozoic marine sediments using Zn isotopes and geochemistry". Earth and Planetary Science Letters, 623 The status of the structures as fossils has been questioned.Javaux, Emmanuelle J.; Lepot, Kevin (January 2018). "The Paleoproterozoic fossil record: Implications for the evolution of the biosphere during Earth's middle-age". Earth-Science Reviews. 176: 68–86. Fakhraee, Mojtaba; Tarhan, Lidya G.; Reinhard, Christopher T.; Crowe, Sean A.; Lyons, Timothy W.; Planavsky, Noah J. (May 2023). "Earth's surface oxygenation and the rise of eukaryotic life: Relationships to the Lomagundi positive carbon isotope excursion revisited". Earth-Science Reviews. 240: 104398.
 	Possible timing for the first fossils of Grypania, an early genus of tube-shaped organism; with a size over one centimeter and consistent form, could have been a giant bacterium, a bacterial colony, or a eukaryotic algae.Han, T. M.; Runnegar, B. (1992-07-10). "Megascopic eukaryotic algae from the 2.1-billion-year-old negaunee iron-formation, Michigan". Science. 257 (5067): 232–235.
2050 - 1800 Mya	Orosirian Period
2000 Mya 	The Oklo natural nuclear reactor of Gabon produced by uranium-precipitant bacteria.
 	The Last Eukaryotic Common Ancestor (LECA), the hypothetical last common ancestor of all living eukaryotes, may have lived around this timeGabaldón, T. (October 2021). "Origin and Early Evolution of the Eukaryotic Cell". Annual Review of Microbiology. 75 (1): 631–647. Woese, C.R.; Kandler, Otto; Wheelis, Mark L. (June 1990). "Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya". Proceedings of the National Academy of Sciences of the United States of America. 87 (12): 4576–4579. and was most likely a biological populationO'Malley, Maureen A.; Leger, Michelle M.; Wideman, Jeremy G.; Ruiz-Trillo, Iñaki (18 February 2019). "Concepts of the last eukaryotic common ancestor". Nature Ecology & Evolution. 3 (3): 338–344. of protists with a nucleus, at least one centriole and cilium, facultatively aerobic mitochondria, sex (meiosis and syngamy), a dormant cyst with a cell wall of chitin and/or cellulose, and peroxisomes.Leander, B. S. (May 2020). "Predatory protists". Current Biology. 30 (10): R510–R516. Strassert, Jürgen F. H.; Irisarri, Iker; Williams, Tom A.; Burki, Fabien (25 March 2021). "A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids". Nature Communications. 12 (1): 1879.
1900 - 1880 Mya	Gunflint chert biota forms flourishes including prokaryotes like Kakabekia, Gunflintia, Animikiea and Eoastrion.
1850 Mya 	Bacterial viruses (bacteriophage) emerge before, or soon after, the divergence of the prokaryotic and eukaryotic lineages.Bernstein H, Bernstein C (May 1989). "Bacteriophage T4 genetic homologies with bacteria and eucaryotes". J. Bacteriol. 171 (5): 2265–70.
 	Eukaryotic cells, containing membrane-bound organelles with diverse functions, probably derived from prokaryotes engulfing each other via phagocytosis.
 	Red beds show an oxidising atmosphere, favouring the spread of eukaryotic life.Knoll, Andrew H.; Javaux, Emmanuelle J.; Hewitt, David; et al. (June 29, 2006). "Eukaryotic organisms in Proterozoic oceans". Philosophical Transactions of the Royal Society B. 361 (1470): 1023–1038.
1800 - 1600 Mya	Statherian Period
1800 Mya 	Acritarchs organic microfossils.
 	Shuiyousphaeridium, an extinct genus of acritarch discovered in 1993, represents one of the earliest fossil eykaryote taxa.Yan, Y. Z.; Liu, Z. L. (1993). "Significance of eukaryotic organisms in the microfossil flora of Changcheng System". Acta Micropalaeontologica Sinica. 10 (2): 167–180.
1730 Mya 	Oldest "clearly indigenous" hydrocarbons biomarkers detected from the Wollogorang Formation in the McArthur Basin in Northern Australia.Vinnichenko, Galina; Jarrett, Amber J. M.; Hope, Janet M.; Brocks, Jochen J. (September 2020). "Discovery of the oldest known biomarkers provides evidence for phototrophic bacteria in the 1.73 Ga Wollogorang Formation, Australia". Geobiology. 18 (5): 544–559.
1640 Mya 	Biomarker evidence for green and purple sulphur bacteria reported from the Barney Creek Formation in the McArthur Basin in Northern Australia.Summons, Roger E; Powell, Trevor G; Boreham, Christopher J (1988-07-01). "Petroleum geology and geochemistry of the Middle Proterozoic McArthur Basin, Northern Australia: III. Composition of extractable hydrocarbons". Geochimica et Cosmochimica Acta. 52 (7): 1747–1763. Brocks, Jochen J.; Love, Gordon D.; Summons, Roger E.; Knoll, Andrew H.; Logan, Graham A.; Bowden, Stephen A. (October 2005). "Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea". Nature. 437 (7060): 866–870.
1635 Mya 	Qingshania magnificia, the earliest known multicellular eukaryote (discovered in Northern China), lived around this time.
 	Tappania, a genus of acanthromorph acritarch, first attested around this time. Tappania plana appears in Paleoproterozoic formations of India (Deonar) and northern China (Baicaoping and Beidajian).  It is a roughly spherical acritarch, 30-60 μm in diameter, with one or two small necks. Small branched and / or partitioned tubes emerge from the central body.Butterfield, Nicholas J. (2015). "Early evolution of the Eukaryota". Palaeontology. 58 (1): 5–17.
 	Other unequivocal unicellular eukaryotes which lived around this time (also discovered from North China) are Shuiyousphaeridium macroreticulatum, Dictyosphaera macroreticulata, Germinosphaera alveolata, and Valeria lophostriata.Miao, L.; Yin, Z.; Knoll, A. H.; Qu, Y.; Zhu, M. (2024). "1.63-billion-year-old multicellular eukaryotes from the Chuanlinggou Formation in North China". Science Advances. 10 (4)
1600 - 1000 Mya	Mesoproterozoic Era
1600 - 1400 Mya	Calymmian Period
1500 Mya 	Volyn biota, a collection of exceptionally well-preserved microfossils with varying morphologies.Franz G., Lyckberg P., Khomenko V., Chournousenko V., Schulz H.-M., Mahlstedt N., Wirth R., Glodny J., Gernert U., Nissen J. (2022). "Fossilization of Precambrian microfossils in the Volyn pegmatite, Ukraine" (PDF). Biogeosciences. 19 (6): 1795–1811.
 	Genus Horodyskia first attested. It is considered one of the oldest known eukaryotes.Retallack, G.J.; Dunn, K.L. & Saxby, J. (2013). "Problematic Mesoproterozoic fossil Horodyskia from Glacier National Park, Montana, USA". Precambrian Research. 226: 125–142. Fedonkin, M.A. (March 2003). "The origin of the Metazoa in the light of the Proterozoic fossil record" (PDF). Paleontological Research. 7 (1): 9–41.
1400 - 1200 Mya	Ectasian Period
1400 Mya 	The Hongshuizhuang Formation in the North China Craton contains hydrocarbons in shales that were likely sourced from prokaryotes.Luo, Qingyong; George, Simon C.; Xu, Yaohui; Zhong, Ningning (2016-09-01). "Organic geochemical characteristics of the Mesoproterozoic Hongshuizhuang Formation from northern China: Implications for thermal maturity and biological sources". Organic Geochemistry. 99: 23–37.
1380 Mya 	Biomarkers found in siltstones from the Roper Group of the McArthur Basin.Jarrett, Amber J. M.; Cox, Grant M.; Brocks, Jochen J.; Grosjean, Emmanuelle; Boreham, Chris J.; Edwards, Dianne S. (July 2019). "Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia". Geobiology. 17 (4): 360–380.
1370 Mya 	Hydrocarbons possibly derived from bacteria and algae reported from the Xiamaling Formation of the NCC.Luo, Genming; Hallmann, Christian; Xie, Shucheng; Ruan, Xiaoyan; Summons, Roger E. (2015-02-15). "Comparative microbial diversity and redox environments of black shale and stromatolite facies in the Mesoproterozoic Xiamaling Formation". Geochimica et Cosmochimica Acta. 151: 150–167.
1300 Mya 	Possible earliest land fungi."First Land Plants and Fungi Changed Earth's Climate, Paving the Way for Explosive Evolution of Land Animals, New Gene Study Suggests". science.psu.edu. Archived from the original on 2018-04-08. Retrieved 10 April 2018. The researchers found that land plants had evolved on Earth by about 700 million years ago and land fungi by about 1,300 million years ago — much earlier than previous estimates of around 480 million years ago, which were based on the earliest fossils of those organisms.
1200 - 1000 Mya	Stenian Period
1200 Mya 	Red alga Bangiomorpha pubescens, earliest fossil evidence for sexually reproducing organism.Butterfield, NJ. (2000). "Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes". Paleobiology. 26 (3): 386–404.
 	Meiosis and sexual reproduction are present in single-celled eukaryotes, and possibly in the common ancestor of all eukaryotes,Bernstein H, Bernstein C, Michod RE (2012). "DNA repair as the primary adaptive function of sex in bacteria and eukaryotes". Chapter 1: pp. 1–49 in: DNA Repair: New Research, Sakura Kimura and Sora Shimizu editors. Nova Sci. Publ., Hauppauge, NY. or in the RNA world.Bernstein, Harris; Byerly, Henry C.; Hopf, Frederic A.; Michod, Richard E. (October 7, 1984). "Origin of sex". Journal of Theoretical Biology. 110 (3): 323–351. Sexual reproduction may have increased the rate of evolution.Butterfield, Nicholas J. (Summer 2000). "Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes". Paleobiology. 26 (3): 386–404.
1100 Mya 	The Atar/El Mreïti Group in the Taoudeni Basin, Mauritania show indigenous biomarkers in black shales.Blumenberg, Martin; Thiel, Volker; Riegel, Walter; Kah, Linda C.; Reitner, Joachim (2012-02-01). "Biomarkers of black shales formed by microbial mats, Late Mesoproterozoic (1.1Ga) Taoudeni Basin, Mauritania". Precambrian Research. 196–197: 113–127.
 	First dinoflagellate evolve; photosynthetic, some develop mixotrophic habits of ingesting prey. Thus, they become the first predators, forcing acritarchs to defensive strategies and leading to open "arms" race.
1010 Mya 	Ourasphaira giraldae: multicellular organic-walled microfossils preserved in shale of the Grassy Bay Formation (Canadian Arctic) with fungal affinity, that may have grown on land a billion years ago, before plants.Loron, Corentin C.; François, Camille; Rainbird, Robert H.; Turner, Elizabeth C.; Borensztajn, Stephan; Javaux, Emmanuelle J. (22 May 2019). "Early fungi from the Proterozoic era in Arctic Canada". Nature. 570 (7760). Springer Science and Business Media LLC: 232–235.
1000 - 538 Mya 	Neoproterozoic Era
1000 - 720 Mya 	Tonian Period
1000 Mya 	First radiation of dinoflagellates and spiny acritarchs; increase in defensive systems indicate that acritarchs are responding to carnivorous habits of dinoflagellates; decline in stromatolite reef populations begins.
 	First vaucherian algae.
 	Trace fossils of colonial Horodyskia.
 	Possible divergence between animal and plant kingdoms begins.
 	First non-marine eukaryotes move onto land. They were photosynthetic and multicellular, indicating that plants evolved much earlier than originally thought.Strother, Paul K.; Battison, Leila; Brasier, Martin D.; Wellman, Charles H. (26 May 2011). "Earth's earliest non-marine eukaryotes". Nature. 473 (7348): 505–509.
900 Mya 	Bitter Springs Formation of Australia: in addition to prokaryote assemblage of fossils, cherts include eukaryotes with ghostly internal structures similar to green algae – first appearance of Glenobotrydion (900–720 Ma), among earliest plants on Earth.
850 Mya 	Melanocyrillium is a Precambrian genus of vesicle-shaped (or vase-shaped) microfossils of uncertain affinity found in the Grand Canyon Supergroup and Togari Group of Tasmania.Bloeser, Bonnie (1985). "Melanocyrillium, a new genus of structurally complex late Proterozoic microfossils from the Kwagunt Formation (Chuar Group), Grand Canyon, Arizona". Journal of Paleontology. 59 (3): 741–765. Riedman, Leigh Anne; Porter, Susannah M.; Calver, Clive R. (December 2018). "Vase-shaped microfossil biostratigraphy with new data from Tasmania, Svalbard, Greenland, Sweden and the Yukon". Precambrian Research. 319: 19–36. M. hexodiadema has been described as a "probable lobose amoeba".Porter SM (2006). "The Proterozoic Fossil Record of Heterotrophic Eukaryotes". In Xiao S, Kaufman AJ (eds.). Neoproterozoic Geolobiology and Paleobiology. Topics in Geobiology. Vol. 27. Dordrecht, The Netherlands: Springer. p. 7.
800 Mya 	Oldest valid eukariotic biomarker records.Brocks JJ, Jarrett AJ, Sirantoine E, Hallmann C, Hoshino Y, Liyanage T (August 2017). "The rise of algae in Cryogenian oceans and the emergence of animals". Nature. 548 (7669): 578–581.
750 Mya 	First Protozoa appears: as creatures like Paramecium, Amoeba and Melanocyrillium evolve, first animal-like cells become distinctive from plants – rise of herbivores (plant feeders) in the food chain.
 	First sponge-like animal: similar to early colonial foraminiferan Horodyskia, earliest ancestors of sponges were colonial cells that circulated food sources using flagella to their gullet to be digested.
 	Beginning of animal evolution.Cunningham, John A.; et al. (5 December 2016). "The origin of animals: Can molecular clocks and the fossil record be reconciled?". BioEssays. 39 (1)
720 - 635 Mya 	Cryogenian Period
700 Mya 	Fossils of testate Amoeba first appear: first complex metazoans leave unconfirmed biomarkers – they introduce new complex body plan architecture which allows for development of complex internal and external structures. Worm trail impressions in China: because putative "burrows" under stromatolite mounds are of uneven width and tapering makes biological origin difficult to defend – structures imply simple feeding behaviours.
650 Mya 	First demosponges appear: form first skeletons of spicules made from protein spongin and silica – brightly coloured these colonial creatures filter feed since they lack nervous, digestive or circulatory systems and reproduce both sexually and asexually.
635 - 338 Mya 	Ediacaran Period
600 Mya 	Acritarch species Vernanimalcula guizhouena first attested.
570 Mya 	Genus Charnia first attested.
567 Mya 	Genus Dickinsonia first attested.
558 Mya 	Erniettomorph genus Pteridinium first attested.
 	Epibaion trace fossil first attested.
555.5 Mya 	Imprints of species Yorgia waggoneri first attested in rocks from the White Sea region of Russia.
555 Mya 	Genus Spriggina attested.
543 Mya 	Monospecific genus of erniettomorph, Swartpuntia, first attested.
===References===
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