Sunday, January 4, 2015

.........


Timeline of evolutionary history of life

From Wikipedia, the free encyclopedia
Not to be confused with History of evolutionary thought.
This article is about the evolution of all life on Earth. For human evolution specifically, see timeline of human evolution. For more detailed and comprehensive coverage, see Evolutionary history of life.
Visual representation of the history of life on Earth as a spiral
Life Graphical Timeline
view • discuss • edit
-4500 —
-4000 —
-3500 —
-3000 —
-2500 —
-2000 —
-1500 —
-1000 —
-500 —
0 —
Formation
of Earth
Atmospheric oxygen
Modern-looking
humans
Axis scale: millions of years ago.
Dates prior to 1000 million years ago are speculative.
This timeline of evolution of life represents the current scientific theory outlining the major events during the development of life on planet Earth. In biologyevolution 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. Although more than 99 percent of all species that ever lived on the planet are estimated to be extinct,[1][2] there are currently 10–14 million species of life on the Earth.[3]
The dates given in this article are estimates based on scientific evidence.

Basic timeline[edit]

In its 4.6 billion years circling the Sun, the Earth has harbored an increasing diversity of life forms:
Periodic extinctions have temporarily reduced diversity, eliminating:
Dates are approximate.

Detailed timeline[edit]

In this timeline, Ma (for megaannum) means "million years ago", ka (for kiloannum) means "thousand years ago", and ya means "years ago".

Hadean Eon[edit]

Main article: Hadean
4000 Ma and earlier.
DateEvent
4600 MaThe planet Earth forms from the accretion disc revolving around the young Suncomplex organic molecules necessary for life may have formed in the protoplanetary disk of dust grains surrounding theSun before the formation of the Earth.[4]
4500 MaAccording 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.[5] The gravitational pull of the new Moon stabilises the Earth's fluctuating axis of rotation and sets up the conditions in which life formed.[6]

Archean Eon[edit]

Main article: Archean
4000 Ma – 2500 Ma
DateEvent
4000 MaFormation of Greenstone belt of the Acasta Gneiss of the Great Slave Region, in Canada, the oldest rock belt in the world.[7]
4100–3800 MaLate Heavy Bombardment: extended barrage of impact events upon the inner planets by meteoroids. Thermal flux from widespread hydrothermal activity during the LHB may have been conducive to life's emergence and early diversification.[8]
3900–2500 MaCells resembling prokaryotes appear.[9] 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.[10][11]
3800 MaFormation of Greenstone belt of the Isua complex of the western Greenland Region, whose rocks show an isotope frequency suggestive of the presence of life.[7] The earliest evidences for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland[12] and microbial mat fossils found in 3.48 billion-year-old sandstonediscovered in Western Australia.[13][14]
3500 MaLifetime of the last universal ancestor;[15][16] the split between bacteria and archaea occurs.[17]
Bacteria develop primitive forms of photosynthesis which at first do not produce oxygen.[18] These organisms generate ATP by exploiting a proton gradient, a mechanism still used in virtually all organisms.
3000 MaPhotosynthesizing cyanobacteria evolve; they use water as a reducing agent, thereby producing oxygen as a waste product.[19] 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[20]

Proterozoic Eon[edit]

Main article: Proterozoic
2500 Ma – 542 Ma
DateEvent
2500 MaGreat Oxidation Event led by Cyanobacteria's oxygenic photosynthesis.[19] Commencement of plate tectonics with old marine crust dense enough to subduct.[7]
2000 MaDiversification and expansion of acritarchs.[21]
By 1850 MaEukaryotic cells appear. Eukaryotes contain membrane-bound organelles with diverse functions, probably derived from prokaryotes engulfing each other via phagocytosis. (See Endosymbiosis). Bacterial viruses (bacteriophage) emerge before, or soon after, the divergence of the prokaryotic and eukaryotic lineages.[22] The appearance of red beds show that an oxidising atmosphere had been produced. Incentives now favoured the spread of eukaryotic life.[23][24][25]
1400 MaGreat increase in stromatolite diversity.
By 1200 MaMeiosis and sexual reproduction are present in single-celled eukaryotes, and possibly in the common ancestor of all eukaryotes.[26] Sex may even have arisen earlier in the RNA world.[27] Sexual reproduction first appears in the fossil records; it may have increased the rate of evolution.[28]
1200 MaSimple multicellular organisms evolve, mostly consisting of cell colonies of limited complexity. First multicellular red algae evolve.
1100 MaEarliest dinoflagellates
1000 MaFirst vaucherian algae (ex: Palaeovaucheria)
750 MaFirst protozoa (ex: Melanocyrillium)
850–630 Maglobal glaciation may have occurred.[29][30] Opinion is divided on whether it increased or decreased biodiversity or the rate of evolution.[31][32][33]
600 MaThe accumulation of atmospheric oxygen allows the formation of an ozone layer.[34] Prior to this, land-based life would probably have required other chemicals to attenuate ultraviolet radiation enough to permit colonisation of the land.[20]
580–542 MaThe Ediacaran biota represent the first large, complex multicellular organisms — although their affinities remain a subject of debate.[35]
580–500 MaMost modern phyla of animals begin to appear in the fossil record during the Cambrian explosion.[36][37]
560 MaEarliest fungi
550 MaFirst fossil evidence for ctenophora (comb jellies), porifera (sponges), and anthozoa (corals & anemones)

Phanerozoic Eon[edit]

Main article: Phanerozoic
542 Ma – present
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.

Paleozoic Era[edit]

Main article: Paleozoic
542 Ma – 251.0 Ma
DateEvent
535 MaMajor diversification of living things in the oceans: chordatesarthropods (e.g. trilobitescrustaceans), echinodermsmollusksbrachiopodsforaminifers and radiolarians, etc.
530 MaThe first known footprints on land date to 530 Ma, indicating that early animal explorations may have predated the development of terrestrial plants.[38]
525 MaEarliest graptolites.
510 MaFirst cephalopods (Nautiloids) and chitons.
505 MaFossilization of the Burgess Shale.
485 MaFirst vertebrates with true bones (jawless fishes).
450 MaFirst complete conodonts and echinoids appear.
440 MaFirst agnathan fishes: HeterostraciGaleaspida, and Pituriaspida.
434 MaThe first primitive plants move onto land,[39] having evolved from green algae living along the edges of lakes.[40] They are accompanied by fungi[citation needed], which may have aided the colonization of land through symbiosis.
420 MaEarliest ray-finned fishestrigonotarbid arachnids, and land scorpions.
410 MaFirst signs of teeth in fish. Earliest nautiid nautiloidslycophytes, and trimerophytes.
395 MaFirst lichensstoneworts. Earliest harvestmanmiteshexapods (springtails) and ammonoids. The first known tetrapod tracks on land.
363 MaBy 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,[41] 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 MaFirst crabs and ferns. Land flora dominated by seed ferns.
350 MaFirst large sharks, ratfishes, and hagfish.
340 MaDiversification of amphibians.
330 MaFirst amniote vertebrates (Paleothyris).
320 MaSynapsids (pre-cursors to mammals) separate from sauropsids (reptiles) in late Carboniferous.[42]
305 MaEarliest diapsid reptiles (e.g. Petrolacosaurus).
280 MaEarliest beetles, seed plants and conifers diversify while lepidodendrids and sphenopsids decrease. Terrestrial temnospondyl amphibians and pelycosaurs (e.g. Dimetrodon) diversify in species.
275 MaTherapsids separate from synapsids.
251.4 MaThe 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.[43]

Mesozoic Era[edit]

Main article: Mesozoic
DateEvent
From 251.4 MaThe 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.
245 MaEarliest ichthyosaurs.
240 MaIncrease in diversity of gomphodont cynodonts and rhynchosaurs.
225 MaEarliest dinosaurs (prosauropods), first cardiid bivalves, diversity in cycads, bennettitaleans, and conifers. First teleost fishes. First mammals (Adelobasileus).
220 MaGymnosperm forests dominate the land; herbivores grow to huge sizes to accommodate the large guts necessary to digest the nutrient-poor plants.[citation needed], first flies and turtles (Odontochelys). First Coelophysoid dinosaurs
200 MaThe first accepted evidence for viruses that infect eukaryotic cells (at least, the group Geminiviridae) exists.[44] 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
195 MaFirst pterosaurs with specialized feeding (Dorygnathus). First sauropod dinosaurs. Diversification in small, ornithischian dinosaursheterodontosauridsfabrosaurids, and scelidosaurids.
190 MaPliosaurs appear in the fossil record. First lepidopteran insects (Archaeolepis), hermit crabs, modern starfish, irregular echinoidscorbulid bivalves, and tubulipore bryozoans. Extensive development of sponge reefs.
176 MaFirst members of the Stegosauria group of dinosaurs
170 MaEarliest salamandersnewtscryptoclidid & elasmosaurid plesiosaurs, and cladotherian mammalsSauropod dinosaurs diversify.
165 MaFirst rays and glycymeridid bivalves.
163 MaPterodactyloid pterosaurs first appear.[45]
161 MaCeratopsian dinosaurs appear in the fossil record (Yinlong)
155 MaFirst blood-sucking insects (ceratopogonids), rudist bivalves, and cheilostome bryozoans. Archaeopteryx, a possible ancestor to the birds, appears in the fossil record, along with triconodontid andsymmetrodont mammals. Diversity in stegosaurian and theropod dinosaurs.
130 MaThe 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.
120 MaOldest fossils of heterokonts, including both marine diatoms and silicoflagellates.
115 MaFirst monotreme mammals.
110 MaFirst hesperornithes, toothed diving birds. Earliest limopsidverticordiid, and thyasirid bivalves.
106 MaSpinosaurus, the largest theropod dinosaur, appears in the fossil record.
100 MaEarliest bees.
90 MaExtinction of ichthyosaurs. Earliest snakes and nuculanid bivalves. Large diversification in angiosperms: magnoliidsrosidshamamelididsmonocots, and ginger. Earliest examples of ticks. Probable origins of placental mammals (earliest undisputed fossil evidence is 66 Ma).
80 MaFirst ants.
70 MaMultituberculate mammals increase in diversity. First yoldiid bivalves.
68 MaTyrannosaurus, the largest terrestrial predator of North America appears in the fossil record. First species of Triceratops.

Cenozoic Era[edit]

Main article: Cenozoic
66 Ma – present
DateEvent
66 MaThe Cretaceous–Paleogene extinction event eradicates about half of all animal species, including mosasaurspterosaursplesiosaursammonitesbelemnites, rudist and inoceramid bivalves, most planktic foraminifers, and all of the dinosaurs excluding their descendants, the birds.[46]
From 66 MaRapid dominance of conifers and ginkgos in high latitudes, along with mammals becoming the dominant species. First psammobiid bivalves. Rapid diversification in ants.
63 MaEvolution of the creodonts, an important group of carnivorous mammals.
60 MaDiversification of large, flightless birds. Earliest true primates, along with the first semelid bivalvesedentatescarnivorous and lipotyphlan mammals, and owls. The ancestors of the carnivorous mammals (miacids) were alive.
56 MaGastornis, a large, flightless bird appears in the fossil record, becoming an apex predator at the time.
55 MaModern bird groups diversify (first song birdsparrotsloonsswiftswoodpeckers), first whale (Himalayacetus), earliest rodentslagomorphsarmadillos, appearance of sireniansproboscideans,perissodactyl and artiodactyl mammals in the fossil record. Angiosperms diversify. The ancestor (according to theory) of the species in Carcharodon, the early mako shark Isurus hastalis, is alive.
52 MaFirst bats appear (Onychonycteris).
50 MaPeak diversity of dinoflagellates and nanofossils, increase in diversity of anomalodesmatan and heteroconch bivalves, brontotherestapirsrhinoceroses, and camels appear in the fossil record, diversification of primates.
40 MaModern-type butterflies and moths appear. Extinction of GastornisBasilosaurus, one of the first of the giant whales, appeared in the fossil record.
37 MaFirst Nimravid carnivores ("false saber-toothed cats") — these species are unrelated to modern-type felines
35 MaGrasses evolve from among the angiosperms; grasslands begin to expand. Slight increase in diversity of cold-tolerant ostracods and foraminifers, along with major extinctions of gastropodsreptiles, and amphibians. Many modern mammal groups begin to appear: first glyptodontsground slothsdogspeccaries, and the first eagles and hawks. Diversity in toothed and baleen whales.
33 MaEvolution of the thylacinid marsupials (Badjcinus).
30 MaFirst balanids and eucalypts, extinction of embrithopod and brontothere mammals, earliest pigs and cats.
28 MaParaceratherium appears in the fossil record, the largest terrestrial mammal that ever lived.
25 MaPelagornis sandersi appears in the fossil record, the largest bird that ever lived.
25 MaFirst deer.
20 MaFirst giraffeshyenasbears and giant anteaters, increase in bird diversity.
15 MaMammut appears in the fossil record, first bovids and kangaroos, diversity in Australian megafauna.
10 MaGrasslands and savannas are established, diversity in insects, especially ants and termiteshorses increase in body size and develop high-crowned teeth, major diversification in grassland mammals and snakes.
6.5 MaFirst hominin (Sahelanthropus).
6 MaAustralopithecines diversify (OrrorinArdipithecus)
5 MaFirst 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
4.8 MaMammoths appear in the fossil record.
4 MaEvolution of AustralopithecusStupendemys appears in the fossil record as the largest freshwater turtle, first modern elephantsgiraffeszebraslionsrhinos and gazelles appear in the fossil record.
3 MaThe Great American Interchange, where various land and freshwater faunas migrated between North and South America. Armadillosopossumshummingbirds, and vampire bats traveled to North America while horses, tapirssaber-toothed cats, and deer entered South America. The first short-faced bears (Arctodus) appear.
2.7 MaEvolution of Paranthropus
2.5 MaThe earliest species of Smilodon evolve
2 MaFirst members of the genus Homo appear in the fossil record. Diversification of conifers in high latitudes. The eventual ancestor of cattle, Bos primigenus evolves in India
1.7 MaExtinction of australopithecines.
1.2 MaEvolution of Homo antecessor. The last members of Paranthropus die out.
600 kaEvolution of Homo heidelbergensis
350 kaEvolution of Neanderthals
300 kaGigantopithecus, a giant relative of the orangutan dies out from Asia
200 kaAnatomically modern humans appear in Africa.[47][48][49] Around 50,000 years before present they start colonising the other continents, replacing the Neanderthals in Europe and other hominins in Asia.
40 kaThe last of the giant monitor lizards (Megalania) die out
30 kaExtinction of Neanderthals, first domestic dogs.
15 kaThe last woolly rhinoceros (Coelodonta) are believed to have gone extinct
11 kaThe giant short-faced bears (Arctodus) vanish from North America, with the last giant ground sloths dying out. All Equidae become extinct in North America
10 kaThe Holocene Epoch starts 10,000[50] years ago after the Late Glacial Maximum. The last mainland species of woolly mammoth (Mammuthus primigenus) die out, as does the last Smilodon species
Historical extinctions[edit]
DateEvent
6000 yaSmall populations of American mastodon die off in places like Utah and Michigan
4500 yaThe last members of a dwarf race of woolly mammoths vanish from Wrangel Island near Alaska
c. 600 ya (c. 1400)The moa and its predator, Haast's eagle, die out in New Zealand
388 ya (1627)The last recorded wild aurochs die out
327 ya (1688)The dodo goes extinct
247 ya (1768)The Steller's sea cow goes extinct
132 ya (1883)The quagga, a subspecies of zebra, goes extinct
101 ya (1914)Martha, last known passenger pigeon, dies
79 ya (1936)The thylacine goes extinct in a Tasmanian zoo, the last member of the family Thylacinidae
63 ya (1952)The Caribbean monk seal goes extinct[51]
7 ya (2008)The baiji, the Yangtze river dolphin, becomes functionally extinct

See also[edit]

Further reading[edit]

References[edit]

  1. Jump up^ Stearns, Beverly Peterson; Stearns, S. C.; Stearns, Stephen C. (2000). Watching, from the Edge of ExtinctionYale University Press. p. 1921. ISBN 978-0-300-08469-6. Retrieved 27 December 2014.
  2. Jump up^ Novacek, Michael J. (8 November 2014). "Prehistory’s Brilliant Future"New York Times. Retrieved25 December 2014.
  3. Jump up^ G. Miller; Scott Spoolman (2012). Environmental Science - Biodiversity Is a Crucial Part of the Earth's Natural CapitalCengage Learning. p. 62. ISBN 1-133-70787-4. Retrieved 27 December 2014.
  4. Jump up^ Moskowitz, Clara (29 March 2012). "Life's Building Blocks May Have Formed in Dust Around Young Sun".Space.com. Retrieved 30 March 2012.
  5. Jump up^ 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.
  6. Jump up^ "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.[1] Astrobiology Magazine. (URL accessed on August 7, 2010)
  7. Jump up to:a b c Bjornerud, Marcia, (2005), "Reading the Rocks: the autobiography of the Earth" (Basic Books
  8. Jump up^ Abramov, Oleg; Mojzsis, Stephen J. last2=Mojzsis (2009). "Microbial habitability of the Hadean Earth during the late heavy bombardment"Nature 459 (7245): 419–422. Bibcode:2009Natur.459..419A.doi:10.1038/nature08015PMID 19458721. Retrieved May 26, 2013.
  9. Jump up^ Carl WoeseJ Peter Gogarten, "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, October 21, 1999.
  10. Jump up^ Romano, AH, Conway, T. (1996). "Evoluti

No comments:

Post a Comment