| Photosynthesizing [[cyanobacteria]] evolve; they use water as a [[reducing agent]], thereby producing oxygen as waste product.<ref name="Buick, R. 2008">{{cite journal |author=Buick R |title=When did oxygenic photosynthesis evolve? |journal=Philos. Trans. R. Soc. Lond., B, Biol. Sci. |volume=363 |issue=1504 |pages=2731–43 |year=2008 |month=August |pmid=18468984 |doi=10.1098/rstb.2008.0041 |pmc=2606769}}</ref> The oxygen initially oxidizes dissolved iron in the oceans, creating [[iron ore]]. The oxygen concentration in the atmosphere slowly rises, acting as a [[poison]] for many bacteria. The [[Moon]] is still very close to Earth and causes [[tide]]s {{convert|1000|ft|m|sigfig=3}} high. The Earth is continually wracked by [[hurricane]]-force winds. These extreme mixing influences are thought to stimulate evolutionary processes. (See [[Oxygen catastrophe]]).
| Photosynthesizing [[cyanobacteria]] evolve; they use water as a [[reducing agent]], thereby producing oxygen as waste product.<ref name="Buick, R. 2008">{{cite journal |author=Buick R |title=When did oxygenic photosynthesis evolve? |journal=Philos. Trans. R. Soc. Lond., B, Biol. Sci. |volume=363 |issue=1504 |pages=2731–43 |year=2008 |month=August |pmid=18468984 |doi=10.1098/rstb.2008.0041 |pmc=2606769}}</ref> The oxygen initially oxidizes dissolved iron in the oceans, creating [[iron ore]]. The oxygen concentration in the atmosphere slowly rises, acting as a [[poison]] for many bacteria. The [[Moon]] is still very close to Earth and causes [[tide]]s {{convert|1000|ft|m|sigfig=3}} high. The Earth is continually wracked by [[hurricane]]-force winds. These extreme mixing influences are thought to stimulate evolutionary processes. (See [[Oxygen catastrophe]]). Life on land likely developed at this time <ref>{{cite journal |author=Beraldi-Campesi H |title=Early life on land |journal=Ecol. Proc. |volume=2 |issue=1 |year=2013 |doi=10.1186/2192-1709-2-1}}</ref>
This timeline of evolution of life outlines the major events in the development of life on planet Earth. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules such as DNA and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the process of evolution.
The dates given in this article are estimates based on scientific evidence.
According to the giant impact hypothesis the moon is formed when the planet Earth and the planet Theia collide, sending a very large number of moonlets into orbit around the young Earth which eventually coalesce to form the Moon.[2] The gravitational pull of the new Moon stabilises the Earth's fluctuating axis of rotation and sets up the conditions in which life formed.[3]
4100 Ma
The surface of the Earth cools enough for the crust to solidify. The atmosphere and the oceans form.[4]
Cells resembling prokaryotes appear.[8] These first organisms are chemoautotrophs: they use carbon dioxide as a carbon source and oxidize inorganic materials to extract energy. Later, prokaryotes evolve glycolysis, a set of chemical reactions that free the energy of organic molecules such as glucose and store it in the chemical bonds of ATP. Glycolysis (and ATP) continue to be used in almost all organisms, unchanged, to this day.[9][10]
3800 Ma
Formation of Greenstone belt of the Isua complex of the western Greenland Region, whose rocks show an isotope frequency suggestive of the presence of life.[5]
Bacteria develop primitive forms of photosynthesis which at first do not produce oxygen.[14] These organisms generate ATP by exploiting a proton gradient, a mechanism still used in virtually all organisms.
3000 Ma
Photosynthesizing cyanobacteria evolve; they use water as a reducing agent, thereby producing oxygen as waste product.[15] The oxygen initially oxidizes dissolved iron in the oceans, creating iron ore. The oxygen concentration in the atmosphere slowly rises, acting as a poison for many bacteria. The Moon is still very close to Earth and causes tides 1,000 feet (305 m) high. The Earth is continually wracked by hurricane-force winds. These extreme mixing influences are thought to stimulate evolutionary processes. (See Oxygen catastrophe). Life on land likely developed at this time [16]
Eukaryotic cells appear. Eukaryotes contain membrane-bound organelles with diverse functions, probably derived from prokaryotes engulfing each other via phagocytosis. (See Endosymbiosis). The appearance of red beds show that an oxidising atmosphere had been produced. Incentives now favoured the spread of eukaryotic life.[18][19][20]
A global glaciation may have occurred.[22][23] Opinion is divided on whether it increased or decreased biodiversity or the rate of evolution.[24][25][26]
580–542 Ma
The Ediacaran biota represent the first large, complex multicellular organisms - although their affinities remain a subject of debate.[27]
The accumulation of atmospheric oxygen allows the formation of an ozone layer.[30] This blocks ultraviolet radiation, permitting the colonisation of the land.[30]
The Phanerozoic Eon, literally the "period of well-displayed life", marks the appearance in the fossil record of abundant, shell-forming and/or trace-making organisms. It is subdivided into three eras, the Paleozoic, Mesozoic and Cenozoic, which are divided by major mass extinctions.
The first known footprints on land date to 530 Ma, indicating that early animal explorations may have predated the development of terrestrial plants.[31]
The first primitive plants move onto land,[32] having evolved from green algae living along the edges of lakes.[33] They are accompanied by fungi[citation needed], which may have aided the colonization of land through symbiosis.
By the start of the Carboniferous Period, the Earth begins to be recognisable. Insects roamed the land and would soon take to the skies; sharks swam the oceans as top predators,[34] and vegetation covered the land, with seed-bearing plants and forests soon to flourish.
Four-limbed tetrapods gradually gain adaptations which will help them occupy a terrestrial life-habit.
360 Ma
First crabs and ferns. Land flora dominated by seed ferns.
The Permian-Triassic extinction event eliminates over 90-95% of marine species. Terrestrial organisms were not as seriously affected as the marine biota. This "clearing of the slate" may have led to an ensuing diversification, but life on land took 30M years to completely recover.[36]
The Mesozoic Marine Revolution begins: increasingly well-adapted and diverse predators pressurize sessile marine groups; the "balance of power" in the oceans shifts dramatically as some groups of prey adapt more rapidly and effectively than others.
The first accepted evidence for viruses (at least, the group Geminiviridae) exists.[37] Viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon.
Major extinctions in terrestrial vertebrates and large amphibians. Earliest examples of Ankylosaurian dinosaurs
The rise of the Angiosperms: These flowering plants boast structures that attract insects and other animals to spread pollen. This innovation causes a major burst of animal evolution through co-evolution. First freshwater pelomedusid turtles.
Peak diversity of dinoflagellates and nanofossils, increase in diversity of anomalodesmatan and heteroconch bivalves, brontotheres, tapirs, rhinoceroses, and camels appear in the fossil record, diversification of primates.
40 Ma
Modern-type butterflies and moths appear. Extinction of Gastornis. Basilosaurus, one of the first of the giant whales, appeared in the fossil record.
37 Ma
First Nimravid carnivores ("False Saber-toothed Cats") - these species are unrelated to modern-type felines
Grasslands and savannas are established, diversity in insects, especially ants and termites, horses increase in body size and develop high-crowned teeth, major diversification in grassland mammals and snakes.
First tree sloths and hippopotami, diversification of grazing herbivores like zebras and elephants, large carnivorous mammals like lions and dogs, burrowing rodents, kangaroos, birds, and small carnivores, vultures increase in size, decrease in the number of perissodactyl mammals. Extinction of Nimravid carnivores
First members of the genus Homo appear in the fossil record. Diversification of conifers in high latitudes. The eventual ancestor of cattle, Bos primigenius evolves in India
The last Woolly rhinoceros (Coelodonta) are believed to have gone extinct
11 ka
The giant short-faced bears (Arctodus) vanish from North America, with the last Giant Ground Sloths dying out. All Equidae become extinct in North America
^Planetary Science Institute page on the Giant Impact Hypothesis. Hartmann and Davis belonged to the PSI. This page also contains several paintings of the impact by Hartmann himself.
^"Because the Moon helps stabilize the tilt of the Earth's rotation, it prevents the Earth from wobbling between climatic extremes. Without the Moon, seasonal shifts would likely outpace even the most adaptable forms of life."
Making the Moon Astrobiology Magazine. (URL accessed on August 7, 2010)
^"However, once the Earth cooled sufficiently, sometime in the first 700 million years of its existence, clouds began to form in the atmosphere, and the Earth entered a new phase of development." How the Oceans Formed (URL accessed on January 9, 2005)
^ abcBjornerud, Marcia, (2005), "Readind the Rocks: the autobiography of the Earth" (Basic Books
^" Between about 3.8 billion and 4.5 billion years ago, no place in the solar system was safe from the huge arsenal of asteroids and comets left over from the formation of the planets. Sleep and Zahnle calculate that Earth was probably hit repeatedly by objects up to 500 kilometers across" Geophysicist Sleep: Martian underground may have harbored early life (URL accessed on January 9, 2005)
^Nicolas Glansdorff, Ying Xu & Bernard Labedan: The Last Universal Common Ancestor : emergence, constitution and genetic legacy of an elusive forerunner. Biology Direct 2008, 3:29.
^Hahn, Jürgen (1986). "Traces of Archaebacteria in ancient sediments". System Applied Microbiology. 7 (Archaebacteria '85 Proceedings): 178–83. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/nature08793, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/nature08793 instead.
^p.151, Bjornerund, Marcia (2005), "Reading the Rocks: the autobiography of the Earth" (Basic Books)
^Kirschvink, J.L. (1992). "Late Proterozoic low-latitude global glaciation: The snowball Earth". In Schopf, JW, and Klein, C. (ed.). The Proterozoic Biosphere: A Multidisciplinary Study(PDF). Cambridge University Press, Cambridge. pp. 51–52.{{cite book}}: CS1 maint: multiple names: editors list (link)
^Narbonne, Guy (2006). "The Origin and Early Evolution of Animals". Department of Geological Sciences and Geological Engineering, Queen's University. Retrieved 2007-03-10. {{cite web}}: Unknown parameter |month= ignored (help)
^"The oldest fossils of footprints ever found on land hint that animals may have beaten plants out of the primordial seas. Lobster-sized, centipede-like or slug like animals such as Protichnites and Climactichnites made the prints wading out of the ocean and scuttling over sand dunes about 530 million years ago. Previous fossils indicated that animals didn't take this step until 40 million years later." Oldest fossil footprints on land
^"The oldest fossils reveal evolution of non-vascular plants by the middle to late Ordovician Period (~450–440 Ma) on the basis of fossil spores" Transition of plants to land
^"The land plants evolved from the algae, more specifically green algae, as suggested by certain common
biochemical traits" The first land plants
^"Viruses of nearly all the major classes of organisms—animals, plants, fungi and bacteria/archaea—probably evolved with their hosts in the seas, given that most of the evolution of life on this planet has occurred there. This means that viruses also probably emerged from the waters with their different hosts, during the successive waves of colonisation of the terrestrial environment." Origins of Viruses (URL accessed on January 9, 2005)
^
Chiappe, Luis M., & Dyke, Gareth J. (2002). "The Mesozoic Radiation of Birds". Annual Review of Ecology & Systematics. 33 (1): 91–124. doi:10.1146/annurev.ecolsys.33.010802.150517.{{cite journal}}: CS1 maint: multiple names: authors list (link)
