Cambrian explosion


The Cambrian explosion, Cambrian radiation,[1] Cambrian diversification, or the Biological Big Bang[2] refers to an interval of time approximately 538.8 million years ago in the Cambrian Period when practically all major animal phyla started appearing in the fossil record.[3][4][5] It lasted for about 13[6][7][8] – 25[9][10] million years and resulted in the divergence of most modern metazoan phyla.[11] The event was accompanied by major diversification in other groups of organisms as well.[a]

Before early Cambrian diversification,[b] most organisms were relatively simple, composed of individual cells, or small multicellular organisms, occasionally organized into colonies. As the rate of diversification subsequently accelerated, the variety of life became much more complex, and began to resemble that of today.[13] Almost all present-day animal phyla appeared during this period,[14][15] including the earliest chordates.[16]

A 2019 paper suggests that the timing should be expanded back to include the late Ediacaran, rather than just the narrower timeframe of the "Cambrian Explosion" event visible in the fossil record, based on analysis of chemicals that would have laid the building blocks for a progression of transitional radiations starting with the Ediacaran period and continuing at a similar rate into the Cambrian.[17]

  1. ^ Zhuravlev, Andrey; Riding, Robert (2000). The Ecology of the Cambrian Radiation. Columbia University Press. ISBN 978-0-231-10613-9. The Cambrian radiation was the explosive evolution of marine life that started 550,000,000 years ago. It ranks as one of the most important episodes in Earth history. This key event in the history of life on our planet changed the marine biosphere and its sedimentary environment forever, requiring a complex interplay of wide-ranging biologic and nonbiologic processes.
  2. ^ Koonin, Eugene V (2007-08-20). "The Biological Big Bang model for the major transitions in evolution". Biology Direct. 2: 21. doi:10.1186/1745-6150-2-21. ISSN 1745-6150. PMC 1973067. PMID 17708768.
  3. ^ "Stratigraphic Chart 2022" (PDF). International Stratigraphic Commission. February 2022. Retrieved 22 April 2022.
  4. ^ Maloof, A. C.; Porter, S. M.; Moore, J. L.; Dudas, F. O.; Bowring, S. A.; Higgins, J. A.; Fike, D. A.; Eddy, M. P. (2010). "The earliest Cambrian record of animals and ocean geochemical change". Geological Society of America Bulletin. 122 (11–12): 1731–1774. Bibcode:2010GSAB..122.1731M. doi:10.1130/B30346.1.
  5. ^ "New Timeline for Appearances of Skeletal Animals in Fossil Record Developed by UCSB Researchers". The Regents of the University of California. 10 November 2010. Retrieved 1 September 2014.
  6. ^ Calibrating rates of early Cambrian evolution, Science 1993, 261(5126), s. 1293–1298. SA Bowring, JP Grotzinger, CE Isachsen, AH Knoll, SM Pelechaty, P Kolosov
  7. ^ Valentine, JW; Jablonski, D; Erwin, DH (1999). "Fossils, molecules and embryos: new perspectives on the Cambrian explosion". Development. 126 (5): 851–9. doi:10.1242/dev.126.5.851. PMID 9927587.
  8. ^ Budd, Graham (2013). "At the origin of animals: the revolutionary cambrian fossil record". Current Genomics. 14 (6): 344–354. doi:10.2174/13892029113149990011. PMC 3861885. PMID 24396267.
  9. ^ Erwin, D. H.; Laflamme, M.; Tweedt, S. M.; Sperling, E. A.; Pisani, D.; Peterson, K. J. (2011). "The Cambrian conundrum: early divergence and later ecological success in the early history of animals". Science. 334 (6059): 1091–1097. Bibcode:2011Sci...334.1091E. doi:10.1126/science.1206375. PMID 22116879. S2CID 7737847.
  10. ^ Kouchinsky, A.; Bengtson, S.; Runnegar, B. N.; Skovsted, C. B.; Steiner, M.; Vendrasco, M. J. (2012). "Chronology of early Cambrian biomineralization". Geological Magazine. 149 (2): 221–251. Bibcode:2012GeoM..149..221K. doi:10.1017/s0016756811000720.
  11. ^ Conway Morris, S. (2003). "The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied?". The International Journal of Developmental Biology. 47 (7–8): 505–15. PMID 14756326.
  12. ^ Cite error: The named reference Butterfield2001ECR was invoked but never defined (see the help page).
  13. ^ Bambach, R.K.; Bush, A.M.; Erwin, D.H. (2007). "Autecology and the filling of Ecospace: Key metazoan radiations". Palæontology. 50 (1): 1–22. doi:10.1111/j.1475-4983.2006.00611.x.
  14. ^ Cite error: The named reference Budd2000 was invoked but never defined (see the help page).
  15. ^ Budd, G.E. (2003). "The Cambrian Fossil Record and the Origin of the Phyla". Integrative and Comparative Biology. 43 (1): 157–165. doi:10.1093/icb/43.1.157. PMID 21680420.
  16. ^ McMenamin, Mark A. S. (2019). "Cambrian Chordates and Vetulicolians". Geosciences. 9 (8): 354. Bibcode:2019Geosc...9..354M. doi:10.3390/geosciences9080354. ISSN 2076-3263.
  17. ^ Wood, R.; Liu, A.G.; Bowyer, F.; Wilby, P.R.; Dunn, F.S.; Kenchington, C.G.; Cuthill, J.F.H.; Mitchell, E.G.; Penny, A. (2019). "Integrated records of environmental change and evolution challenge the Cambrian Explosion". Nature Ecology & Evolution. 3 (4): 528–538. doi:10.1038/s41559-019-0821-6. PMID 30858589.


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