Timeline of the evolutionary history of life

The timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. Dates in this article are consensus estimates based on scientific evidence, mainly fossils.

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 imply a common ancestor from which all known species, living and extinct, have diverged. More than 99 percent of all species that ever lived (over five billion)[1] are estimated to be extinct.[2][3] Estimates on the number of Earth's current species range from 10 million to 14 million,[4] with about 1.2 million or 14% documented, the rest not yet described.[5] However, a 2016 report estimates an additional 1 trillion microbial species, with only 0.001% described.[6]

There has been controversy between more traditional views of steadily increasing biodiversity, and a newer view of cycles of annihilation and diversification, so that certain past times, such as the Cambrian explosion, experienced maximums of diversity followed by sharp winnowing.[7][8]

  1. ^ McKinney 1997, p. 110
  2. ^ Stearns, Beverly Peterson; Stearns, S. C.; Stearns, Stephen C. (2000). Watching, from the Edge of Extinction. Yale University Press. p. preface x. ISBN 978-0-300-08469-6. Retrieved 30 May 2017.
  3. ^ Novacek, Michael J. (November 8, 2014). "Prehistory's Brilliant Future". The New York Times. New York. ISSN 0362-4331. Archived from the original on 2022-01-01. Retrieved 2014-12-25.
  4. ^ Miller & Spoolman 2012, p. 62
  5. ^ Mora, Camilo; Tittensor, Derek P.; Adl, Sina; et al. (August 23, 2011). "How Many Species Are There on Earth and in the Ocean?". PLOS Biology. 9 (8): e1001127. doi:10.1371/journal.pbio.1001127. ISSN 1545-7885. PMC 3160336. PMID 21886479.
  6. ^ Staff (2 May 2016). "Researchers find that Earth may be home to 1 trillion species". National Science Foundation. Retrieved 11 April 2018.
  7. ^ Hickman, Crystal; Starn, Autumn. "The Burgess Shale & Models of Evolution". Reconstructions of the Burgess Shale and What They Mean... Morgantown, WV: West Virginia University. Retrieved 2015-10-18.
  8. ^ Barton et al. 2007, Figure 10.20 Four diagrams of evolutionary models

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