- For the Cretaceous–Paleogene extinction event, see: K-T extinction
Permian–Triassic extinction event was the last and worst of a series of mass extinction events in the Permian period in 252 Ma. This event was Earth's most severe known extinction event of all time, with up to 96% of all marine species and 70% of terrestrial species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years. Studies in Bear Lake County near Paris, Idaho showed a quick and dynamic rebound in a marine ecosystem, illustrating the remarkable resiliency of life.
- (See also: Day 4)
The climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an ice age, which began in the Carboniferous. Glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continent's interiors for thirteen million years. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles for another eight million years until the occurrence of the P-T extinction event in 252 Ma.
- 272.95 – 252 million years ago
An unknown global warming phenomena caused an abrupt climate change to have occurred as early as the Guadalupian age (272.95 Ma). The anomaly triggered a runaway greenhouse effect that caused the most severe anoxic conditions in Earth's oceanic history, which led to the "The Great Dying" (P–T extinction) in 252 Ma. There are several developing theories as to what contributed to the anoxic oceans:
- Clathrate gun hypothesis, where increases in sea temperatures (and/or drops in sea levels) can trigger a catastrophic positive feedback effect on climate:: first, warming causes a sudden release of methane from methane clathrate compounds buried in seabeds and seabed permafrost; second, because methane itself is a powerful greenhouse gas, temperatures rise further, and the cycle repeats. This runaway process, once started, could be as irreversible as the firing of a gun.
- In 2015, evidence and a timeline indicated that the extinction was caused by events in the Large igneous province of the Siberian Traps. The Siberian Traps eruptions, which occurred near coal beds and the continental shelf, triggered very large releases of carbon dioxide and methane. Another possible contributor to the extinction may have been from the aftermath of earlier volcanism from the Emeishan Traps in south-western China.
- Sea levels in the Permian remained generally low, and near-shore environments were reduced as almost all major landmasses collected into a single continent – Pangaea. Due to the land mass reconfiguration by the end of the period, the reduction of shallow coastal areas that were preferred by many marine organisms, may have contributed to the widespread extinctions of marine species.
- The already shallow waters that contained anaerobic sulfur-reducing organisms, dominated the chemistry of the oceans, and the warming of water temperatures may have caused massive emissions of toxic hydrogen sulfide.
|Permian extinctions (mya: millions years ago)|
- ↑ 1.0 1.1 Benton M J (2005). When life nearly died: the greatest mass extinction of all time. London: Thames & Hudson. ISBN 0-500-28573-X.
- ↑ Carl T. Bergstrom; Lee Alan Dugatkin (2012). Evolution. Norton. p. 515. ISBN 978-0-393-92592-0. https://books.google.com/books?id=SeaEZwEACAAJ.
- ↑ Sahney S; Benton M.J (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B 275 (1636): 759–765. doi:10.1098/rspb.2007.1370. PMID 18198148. PMC: 2596898. http://rspb.royalsocietypublishing.org/content/275/1636/759.full.
- ↑ "Insect diversity in the fossil record". Science 261 (5119): 310–315. 1993. doi:10.1126/science.11536548. PMID 11536548. Bibcode: 1993Sci...261..310L.
- ↑ "Extinctions and Biodiversity in the Fossil Record". Encyclopedia of Global Environmental Change, The Earth System – Biological and Ecological Dimensions of Global Environmental Change (Volume 2). New York: Wiley. 2003. pp. 297–391. ISBN 0-470-85361-1.
- ↑ "It Took Earth Ten Million Years to Recover from Greatest Mass Extinction". ScienceDaily. 27 May 2012. http://www.sciencedaily.com/releases/2012/05/120527153810.htm. Retrieved on 28 May 2012.
- ↑ "Fossils show quick rebound of life after ancient mass extinction". Reuters. 2017-02-15. https://www.reuters.com/article/us-science-extinction-idUSKBN15U2L3.
- ↑ Palaeos: Life Through Deep Time > The Permian Period Accessed 1 April 2013.
- ↑ Kennett, James P.; Cannariato, Kevin G.; Hendy, Ingrid L.; Behl, Richard J. (2003). Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis. Washington DC: American Geophysical Union. ISBN 0-87590-296-0. http://onlinelibrary.wiley.com/book/10.1029/054SP.
- ↑ Burgess, Seth D.; Bowring, Samuel; Shen, Shu-zhong (2014-03-04). "High-precision timeline for Earth’s most severe extinction" (in en). Proceedings of the National Academy of Sciences 111 (9): 3316–3321. doi:10.1073/pnas.1317692111. ISSN 0027-8424. PMID 24516148. PMC: 3948271. http://www.pnas.org/content/111/9/3316.
- ↑ "Earth’s worst extinction "inescapably" tied to Siberian Traps, CO2, and climate change". http://www.skepticalscience.com/Burgess-Bowring-2015-Siberian-Traps-Dates.html.
- ↑ Black, Benjamin A.; Weiss, Benjamin P.; Elkins-Tanton, Linda T.; Veselovskiy, Roman V.; Latyshev, Anton (2015-04-30). "Siberian Traps volcaniclastic rocks and the role of magma-water interactions" (in en). Geological Society of America Bulletin 127: B31108.1. doi:10.1130/B31108.1. ISSN 0016-7606. http://gsabulletin.gsapubs.org/content/early/2015/04/30/B31108.1.
- ↑ Burgess, Seth D.; Bowring, Samuel A. (2015-08-01). "High-precision geochronology confirms voluminous magmatism before, during, and after Earth’s most severe extinction" (in en). Science Advances 1 (7): e1500470. doi:10.1126/sciadv.1500470. ISSN 2375-2548. PMID 26601239. PMC: 4643808. http://advances.sciencemag.org/content/1/7/e1500470.
- ↑ Fischman, Josh. "Giant Eruptions and Giant Extinctions [Video"]. http://www.scientificamerican.com/article/giant-eruptions-and-giant-extinctions-video/.
- ↑ 15.0 15.1 Knoll, A.H., Bambach, R.K., Payne, J.L., Pruss, S., and Fischer, W.W. (2007). "Paleophysiology and end-Permian mass extinction". Earth and Planetary Science Letters 256 (3–4): 295–313. doi:10.1016/j.epsl.2007.02.018. Bibcode: 2007E&PSL.256..295K. http://pangea.stanford.edu/~jlpayne/Knoll%20et%20al%202007%20EPSL%20Permian%20Triassic%20paleophysiology.pdf. Retrieved on 4 July 2008.
- ↑ Zhou, M-F., Malpas, J, Song, X-Y, Robinson, PT, Sun, M, Kennedy, AK, Lesher, CM & Keays, RR (2002). "A temporal link between the Emeishan large igneous province (SW China) and the end-Guadalupian mass extinction". Earth and Planetary Science Letters 196 (3–4): 113–122. doi:10.1016/S0012-821X(01)00608-2. Bibcode: 2002E&PSL.196..113Z.
- ↑ Wignall, Paul B.; Sun, Y.; Bond, D. P. G.; Izon, G.; Newton, R. J.; Vedrine, S.; Widdowson, M.; Ali, J. R.; et al. (2009). "Volcanism, Mass Extinction, and Carbon Isotope Fluctuations in the Middle Permian of China". Science 324 (5931): 1179–1182. doi:10.1126/science.1171956. PMID 19478179. Bibcode: 2009Sci...324.1179W.