Editing Permian–Triassic extinction event (section)

== Dating ==
{{P-T extinction graphical timeline}}
Previously, it was thought that rock sequences spanning the Permian–Triassic boundary were too few and contained too many gaps for scientists to reliably determine its details.<ref name="Erwin1993">{{cite book |author=Erwin, D.H. |title=The great Paleozoic crisis; Life and death in the Permian |publisher=[[Columbia University Press]] |year=1993 |isbn=978-0-231-07467-4}}</ref> However, it is now possible to date the extinction with millennial precision. [[Uranium–lead dating|U–Pb]] [[zircon]] dates from five volcanic ash beds from the [[Global Boundary Stratotype Section and Point|Global Stratotype Section and Point]] for the Permian–Triassic boundary at [[Changxing County|Meishan]], [[China]], establish a high-resolution age model for the extinction – allowing exploration of the links between global environmental perturbation, [[carbon cycle]] disruption, mass extinction, and recovery at millennial timescales. The first appearance of the conodont ''[[Hindeodus]] parvus'' has been used to delineate the Permian-Triassic boundary.<ref name=YinGSSP>{{cite journal |vauthors=Yin H, Zhang K, Tong J, Yang Z, Wu S |year=2001 |title=The global stratotype section and point (GSSP) of the Permian–Triassic boundary |journal=[[Episodes (journal)|Episodes]] |volume=24 |issue=2 |pages=102–114 |doi=10.18814/epiiugs/2001/v24i2/004 |doi-access=free}}</ref><ref name=Yin1992>{{cite book |vauthors=Yin HF, Sweets WC, Yang ZY, Dickins JM |year=1992 |chapter=Permo–Triassic events in the eastern Tethys – an overview |editor=Sweet WC |title=Permo–Triassic Events in the Eastern Tethys: Stratigraphy, classification, and relations with the western Tethys |series=World and Regional Geology |publisher=[[Cambridge University Press]] |location=Cambridge |pages=1–7 |isbn=978-0-521-54573-0 |doi=10.1017/CBO9780511529498.002 |url=https://www.cambridge.org/core/books/abs/permotriassic-events-in-the-eastern-tethys/permotriassic-events-in-the-eastern-tethys-an-overview/89DD4B0A574BDC1086A0DA337C3B252E |access-date=3 July 2023}}</ref><ref>{{Cite journal |last=Kershaw |first=Stephen |date=1 April 2017 |title=Palaeogeographic variation in the Permian–Triassic boundary microbialites: A discussion of microbial and ocean processes after the end-Permian mass extinction |journal=Journal of Palaeogeography |volume=6 |issue=2 |pages=97–107 |doi=10.1016/j.jop.2016.12.002 |issn=2095-3836 |doi-access=free |bibcode=2017JPalG...6...97K }}</ref>

The extinction occurred between {{nobr|251.941 ± 0.037}} and {{nobr|251.880 ± 0.031 million}} years ago, a duration of 60 ± 48 thousand years.<ref name=Burgess-2014>{{cite journal |last1=Burgess |first1=Seth D. |last2=Bowring |first2=Samuel |last3=Shen |first3=Shu-zhong |date=10 February 2014 |title=High-precision timeline for Earth's most severe extinction |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |language=en |volume=111 |issue=9 |pages=3316–3321 |pmc=3948271 |bibcode=2014PNAS..111.3316B |doi=10.1073/pnas.1317692111 |doi-access=free |pmid=24516148}}</ref> A large, abrupt global decrease in [[δ13C|δ<sup>13</sup>C]], the [[Isotope analysis|ratio]] of the [[stable isotope]] [[13C|carbon-13]] to that of [[carbon-12]], coincides with this extinction,<ref>{{cite journal |last1=Yuan |first1=Dong-xun |last2=Shen |first2=Shu-zhong |last3=Henderson |first3=Charles M. |last4=Chen |first4=Jun |last5=Zhang |first5=Hua |last6=Feng |first6=Hong-zhen |date=1 September 2014 |title=Revised conodont-based integrated high-resolution timescale for the Changhsingian Stage and end-Permian extinction interval at the Meishan sections, South China |url=https://www.sciencedirect.com/science/article/abs/pii/S0024493714001170 |journal=[[Lithos (journal)|Lithos]] |volume=204 |pages=220–245 |doi=10.1016/j.lithos.2014.03.026 |bibcode=2014Litho.204..220Y |access-date=10 August 2023|url-access=subscription }}</ref><ref>{{cite journal |vauthors=Magaritz M |year=1989 |title=<sup>13</sup>C minima follow extinction events: A clue to faunal radiation |journal=[[Geology (journal)|Geology]] |volume=17 |issue=4 |pages=337–340 |bibcode=1989Geo....17..337M  |doi=10.1130/0091-7613(1989)017<0337:CMFEEA>2.3.CO;2}}</ref><ref>{{cite journal |last1=Musashi |first1=Masaaki |last2=Isozaki |first2=Yukio |last3=Koike |first3=Toshio |last4=Kreulen |first4=Rob |date=30 August 2001 |title=Stable carbon isotope signature in mid-Panthalassa shallow-water carbonates across the Permo–Triassic boundary: Evidence for <sup>13</sup>C-depleted ocean |url=https://www.sciencedirect.com/science/article/abs/pii/S0012821X01003983 |journal=[[Earth and Planetary Science Letters]] |volume=193 |issue=1–2 |pages=9–20 |doi=10.1016/S0012-821X(01)00398-3 |bibcode=2001E&PSL.191....9M |access-date=3 July 2023|url-access=subscription }}</ref> and is sometimes used to identify the Permian–Triassic boundary and PTME in rocks that are unsuitable for [[radiometric dating]].<ref name=DolenecLojenRamovs2001PermianTriassicBoundary>{{cite journal |vauthors=Dolenec T, Lojen S, Ramovs A |year=2001 |title=The Permian-Triassic boundary in Western Slovenia (Idrijca Valley section): magnetostratigraphy, stable isotopes, and elemental variations |journal=[[Chemical Geology]] |volume=175 |issue=1–2 |pages=175–190 |doi=10.1016/S0009-2541(00)00368-5 |bibcode=2001ChGeo.175..175D}}</ref><ref>{{Cite journal |last1=Yuan |first1=Dong-xun |last2=Chen |first2=Jun |last3=Zhang |first3=Yi-chun |last4=Zheng |first4=Quan-feng |last5=Shen |first5=Shu-zhong |date=1 June 2015 |title=Changhsingian conodont succession and the end-Permian mass extinction event at the Daijiagou section in Chongqing, Southwest China |url=https://linkinghub.elsevier.com/retrieve/pii/S1367912015001984 |journal=[[Journal of Asian Earth Sciences]] |language=en |volume=105 |pages=234–251 |doi=10.1016/j.jseaes.2015.04.002 |bibcode=2015JAESc.105..234Y |access-date=18 June 2024 |via=Elsevier Science Direct|url-access=subscription }}</ref> The negative carbon isotope excursion's magnitude was 4–7% and lasted for approximately 500 kyr,<ref>{{cite journal |last1=Korte |first1=Christoph |last2=Kozur |first2=Heinz W. |date=9 September 2010 |title=Carbon-isotope stratigraphy across the Permian–Triassic boundary: A review |url=https://www.sciencedirect.com/science/article/abs/pii/S1367912010000313 |journal=[[Journal of Asian Earth Sciences]] |volume=39 |issue=4 |pages=215–235 |doi=10.1016/j.jseaes.2010.01.005 |bibcode=2010JAESc..39..215K |access-date=26 June 2023|url-access=subscription }}</ref> though estimating its exact value is challenging due to diagenetic alteration of many sedimentary facies spanning the boundary.<ref>{{Cite journal |last1=Li |first1=Rong |last2=Jones |first2=Brian |date=15 February 2017 |title=Diagenetic overprint on negative δ13C excursions across the Permian/Triassic boundary: A case study from Meishan section, China |url=https://www.sciencedirect.com/science/article/pii/S0031018216307933 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=468 |pages=18–33 |doi=10.1016/j.palaeo.2016.11.044 |bibcode=2017PPP...468...18L |issn=0031-0182 |access-date=20 September 2023|url-access=subscription }}</ref><ref>{{cite book |last1=Schobben |first1=Martin |last2=Heuer |first2=Franziska |last3=Tietje |first3=Melanie |last4=Ghaderi |first4=Abbas |last5=Korn |first5=Dieter |last6=Korte |first6=Christoph |last7=Wignall |first7=Paul Barry |editor-last1=Sial |editor-first1=Alcides N. |editor-last2=Gaucher |editor-first2=Claudio |editor-last3=Ramkumar |editor-first3=Muthuvairavasamy |editor-last4=Pinto Ferreira |editor-first4=Valderez |date=19 November 2018 |title=Chemostratigraphy Across Major Chronological Boundaries |url=https://agupubs.onlinelibrary.wiley.com/doi/book/10.1002/9781119382508 |chapter=Chemostratigraphy Across the Permian-Triassic Boundary: The Effect of Sampling Strategies on Carbonate Carbon Isotope Stratigraphic Markers |chapter-url=https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119382508.ch9 |publisher=[[American Geophysical Union]] |pages=159–181 |doi=10.1002/9781119382508.ch9 |isbn=9781119382508 |s2cid=134060610 |access-date=20 September 2023}}</ref>

Further evidence for environmental change around the Permian-Triassic boundary suggests an {{convert|8|C-change|F-change}} rise in temperature,<ref name=McElwain2007/> and an increase in {{chem|CO|2}} levels to {{val|2500|ul=ppm|fmt=commas}} (for comparison, the concentration immediately before the [[Industrial Revolution]] was {{val|280|u=ppm}},<ref name=McElwain2007/> and the amount today is about 422&nbsp;ppm<ref>{{cite web |url=https://www.co2.earth/daily-co2 |title=Daily CO<sub>2</sub> |publisher=Mauna Loa Observatory}}</ref>). There is also evidence of increased [[Ultraviolet|ultraviolet radiation]] reaching the Earth, causing the [[mutation]] of plant spores.<ref name=McElwain2007 /><ref name=EnvironmentalMutagenesis>{{Cite journal |last1=Visscher |first1=Henk |last2=Looy |first2=Cindy V. |last3=Collinson |first3=Margaret E. |last4=Brinkhuis |first4=Henk |last5=Cittert |first5=Johanna H.A. van Konijnenburg |last6=Kürschner |first6=Wolfram M. |last7=Sephton |first7=Mark A. |date=31 August 2004 |title=Environmental mutagenesis during the end-Permian ecological crisis |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=101 |issue=35 |pages=12952–12956 |bibcode=2004PNAS..10112952V |doi=10.1073/pnas.0404472101 |issn=0027-8424 |pmc=516500 |pmid=15282373 |doi-access=free}}</ref>

It has been suggested that the Permian–Triassic boundary is associated with a sharp increase in the abundance of marine and terrestrial [[fungi]], caused by the sharp increase in the amount of dead plants and animals fed upon by the fungi.<ref name=VisscherBrinkhuisEtAl1996TerminalPaleozoicFungalEvent>{{cite journal |vauthors=Visscher H, Brinkhuis H, Dilcher DL, Elsik WC, Eshet Y, Looy CW, Rampino MR, Traverse A |year=1996 |title=The terminal Paleozoic fungal event: Evidence of terrestrial ecosystem destabilization and collapse |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=93 |issue=5 |pages=2155–2158 |doi=10.1073/pnas.93.5.2155 |pmc=39926 |pmid=11607638 
|bibcode=1996PNAS...93.2155V|doi-access=free }}</ref> This "fungal spike" has been used by some [[Paleontology|paleontologists]] to identify a [[lithological]] sequence as being on or very close to the Permian–Triassic boundary in rocks that are unsuitable for radiometric dating or have a lack of suitable [[index fossil]]s.<ref>{{cite journal |last1=Tewari |first1=Rajni |last2=Awatar |first2=Ram |last3=Pandita |first3=Sundeep K. |last4=McLoughlin |first4=Stephen D. |last5=Agnihotri |first5=Deepa |last6=Pillai |first6=Suresh S. K. |last7=Singh |first7=Vartika |last8=Kumar |first8=Kamlesh |last9=Bhat |first9=Ghulam D. |display-authors=6 |date=October 2015 |title=The Permian–Triassic palynological transition in the Guryul Ravine section, Kashmir, India: implications for Tethyan–Gondwanan correlations |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825214001615 |journal=[[Earth-Science Reviews]] |volume=149 |pages=53–66 |doi=10.1016/j.earscirev.2014.08.018 |bibcode=2015ESRv..149...53T |access-date=26 May 2023}}</ref> However, even the proposers of the fungal spike hypothesis pointed out that "fungal spikes" may have been a repeating phenomenon created by the post-extinction ecosystem during the earliest Triassic.<ref name="VisscherBrinkhuisEtAl1996TerminalPaleozoicFungalEvent"/> The very idea of a fungal spike has been criticized on several grounds, including: ''[[Reduviasporonites]]'', the most common supposed fungal spore, may be a fossilized [[alga]];<ref name="McElwain2007" /><ref name=FosterEtAl2002>{{cite journal |vauthors=Foster CB, Stephenson MH, Marshall C, Logan GA, Greenwood PF |year=2002 |title=A revision of Reduviasporonites Wilson 1962: Description, illustration, comparison and biological affinities |journal=Palynology |volume=26 |issue=1 |pages=35–58 |doi=10.2113/0260035 |bibcode=2002Paly...26...35F }}</ref> the spike did not appear worldwide;<ref>{{cite journal |last1=Diez |first1=José B. |last2=Broutin |first2=Jean |last3=Grauvogel-Stamm |first3=Léa |last4=Borquin |first4=Sylvie |last5=Bercovici |first5=Antoine |last6=Ferrer |first6=Javier |date=October 2010 |title=Anisian floras from the NE Iberian Peninsula and Balearic Islands: A synthesis |url=https://www.sciencedirect.com/science/article/abs/pii/S0034666710001892 |journal=[[Review of Palaeobotany and Palynology]] |volume=162 |issue=3 |pages=522–542 |doi=10.1016/j.revpalbo.2010.09.003 |bibcode=2010RPaPa.162..522D |access-date=8 January 2023|url-access=subscription }}</ref><ref>{{cite journal |vauthors=López-Gómez J, Taylor EL |year=2005 |title=Permian–Triassic transition in Spain: A multidisciplinary approach |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=229 |issue=1–2 |pages=1–2 |doi=10.1016/j.palaeo.2005.06.028}}</ref><ref name=LooyEtAl2005EndPermianDeadZone>{{cite journal |vauthors=Looy CV, Twitchett RJ, Dilcher DL, ((van Konijnenburg-Van Cittert JH)), Visscher H |year=2005 |title=Life in the end-Permian dead zone |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=98 |issue=4 |pages=7879–7883 |doi=10.1073/pnas.131218098 |quote=See image 2 |pmid=11427710 |pmc=35436 |bibcode=2001PNAS...98.7879L |doi-access=free}}</ref> and in many places it did not fall on the Permian–Triassic boundary.<ref name="wardetal"/> The ''Reduviasporonites'' may even represent a transition to a lake-dominated Triassic world rather than an earliest Triassic zone of death and decay in some terrestrial fossil beds.<ref name="RetallackEtAl2003VertebrateExtinctionInKaroo">{{cite journal |vauthors=Retallack GJ, Smith RM, Ward PD |year=2003 |title=Vertebrate extinction across Permian-Triassic boundary in Karoo Basin, South Africa |journal=[[Bulletin of the Geological Society of America]] |volume=115 |issue=9 |pages=1133–1152 |doi=10.1130/B25215.1 |bibcode=2003GSAB..115.1133R }}</ref> Newer chemical evidence agrees better with a fungal origin for ''Reduviasporonites'', diluting these critiques.<ref name=Sephton2009>{{cite journal |vauthors=Sephton MA, Visscher H, Looy CV, Verchovsky AB, Watson JS |year=2009 |title=Chemical constitution of a Permian-Triassic disaster species |journal=[[Geology (journal)|Geology]] |volume=37 |issue=10 |pages=875–878 |doi=10.1130/G30096A.1 |bibcode=2009Geo....37..875S}}</ref><ref name="RampinoEshet2018">{{cite journal |last1=Rampino |first1=Michael R. |last2=Eshet |first2=Yoram |date=January 2018 |title=The fungal and acritarch events as time markers for the latest Permian mass extinction: An update |url=https://www.researchgate.net/publication/318472943 |journal=Geoscience Frontiers |volume=9 |issue=1 |pages=147–154 |doi=10.1016/j.gsf.2017.06.005 |bibcode=2018GeoFr...9..147R |access-date=24 December 2022|doi-access=free }}</ref>

Uncertainty exists regarding the duration of the overall extinction and about the timing and duration of various groups' extinctions within the greater process. Some evidence suggests that there were multiple extinction pulses<ref>{{Cite journal |last1=Shen |first1=Jun |last2=Feng |first2=Qinglai |last3=Algeo |first3=Thomas J. |last4=Li |first4=Chao |last5=Planavsky |first5=Noah J. |last6=Zhou |first6=Lian |last7=Zhang |first7=Mingliang |date=1 June 2016 |title=Two pulses of oceanic environmental disturbance during the Permian–Triassic boundary crisis |url=https://linkinghub.elsevier.com/retrieve/pii/S0012821X16301170 |journal=[[Earth and Planetary Science Letters]] |language=en |volume=443 |pages=139–152 |doi=10.1016/j.epsl.2016.03.030 |bibcode=2016E&PSL.443..139S |access-date=18 June 2024 |via=Elsevier Science Direct}}</ref><ref>{{Cite journal |last1=Yin |first1=Hongfu |last2=Jiang |first2=Haishui |last3=Xia |first3=Wenchen |last4=Feng |first4=Qinglai |last5=Zhang |first5=Ning |last6=Shen |first6=Jun |date=October 2014 |title=The end-Permian regression in South China and its implication on mass extinction |url=https://linkinghub.elsevier.com/retrieve/pii/S0012825213001153 |journal=[[Earth-Science Reviews]] |language=en |volume=137 |pages=19–33 |doi=10.1016/j.earscirev.2013.06.003 |bibcode=2014ESRv..137...19Y |access-date=20 September 2023|url-access=subscription }}</ref><ref>{{Cite journal |last1=de Wit |first1=Maarten J. |last2=Ghosh |first2=Joy G. |last3=de Villiers |first3=Stephanie |last4=Rakotosolofo |first4=Nicolas |last5=Alexander |first5=James |last6=Tripathi |first6=Archana |last7=Looy |first7=Cindy |date=March 2002 |title=Multiple Organic Carbon Isotope Reversals across the Permo-Triassic Boundary of Terrestrial Gondwana Sequences: Clues to Extinction Patterns and Delayed Ecosystem Recovery |url=https://www.journals.uchicago.edu/doi/10.1086/338411 |journal=[[The Journal of Geology]] |language=en |volume=110 |issue=2 |pages=227–240 |doi=10.1086/338411 |bibcode=2002JG....110..227D |s2cid=129653925 |issn=0022-1376 |access-date=20 September 2023|url-access=subscription }}</ref> or that the extinction was long and spread out over a few million years, with a sharp peak in the last million years of the Permian.<ref name="YinEtAl2007">{{cite journal |last1=Yin |first1=Hongfu |last2=Feng |first2=Qinglai |last3=Lai |first3=Xulong |last4=Baud |first4=Aymon |last5=Tong |first5=Jinnan |date=January 2007 |title=The protracted Permo-Triassic crisis and multi-episode extinction around the Permian–Triassic boundary |journal=[[Global and Planetary Change]] |volume=55 |issue=1–3 |pages=1–20 |doi=10.1016/j.gloplacha.2006.06.005 |bibcode=2007GPC....55....1Y |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818106001354 |access-date=29 October 2022|url-access=subscription }}</ref><ref name=wardetal>{{cite journal |vauthors=Ward PD, Botha J, Buick R, de Kock MO, Erwin DH, Garrison GH, Kirschvink JL, Smith R |year=2005 |title=Abrupt and gradual extinction among late Permian land vertebrates in the Karoo Basin, South Africa |journal=[[Science (journal)|Science]] |volume=307 |issue=5710 |pages=709–714 |doi=10.1126/science.1107068 |pmid=15661973 
|bibcode=2005Sci...307..709W |s2cid=46198018 |url=http://www.gps.caltech.edu/users/jkirschvink/pdfs/WardKarooScienceFinal.pdf |citeseerx=10.1.1.503.2065}}</ref><ref>{{cite journal |vauthors=Rampino MR, Prokoph A, Adler A |year=2000 |doi=10.1130/0091-7613(2000)28<643:TOTEEH>2.0.CO;2 |title=Tempo of the end-Permian event: High-resolution cyclostratigraphy at the Permian–Triassic boundary |journal=[[Geology (journal)|Geology]] |volume=28 |issue=7 |pages=643–646 |issn=0091-7613 |bibcode=2000Geo....28..643R}}</ref> Statistical analyses of some highly fossiliferous [[Stratum|strata]] in Meishan, [[Zhejiang]] Province in southeastern China, suggest that the main extinction was clustered around one peak,<ref name=Jin2000/> while a study of the Liangfengya section found evidence of two extinction waves, MEH-1 and MEH-2, which varied in their causes,<ref>{{cite journal |last1=Li |first1=Guoshan |last2=Liao |first2=Wei |last3=Li |first3=Sheng |last4=Wang |first4=Yongbiao |last5=Lai |first5=Zhongping |date=23 March 2021 |title=Different triggers for the two pulses of mass extinction across the Permian and Triassic boundary |journal=[[Scientific Reports]] |volume=11 |issue=1 |page=6686 |doi=10.1038/s41598-021-86111-7 |pmid=33758284 |pmc=7988102 |bibcode=2021NatSR..11.6686L }}</ref> and a study of the Shangsi section showed two extinction pulses with different causes too.<ref>{{cite journal |last1=Shen |first1=Jiaheng |last2=Zhang |first2=Yi Ge |last3=Yang |first3=Huan |last4=Xie |first4=Shucheng |last5=Pearson |first5=Ann |date=3 October 2022 |title=Early and late phases of the Permian–Triassic mass extinction marked by different atmospheric {{CO2}} regimes |journal=[[Nature Geoscience]] |volume=15 |issue=1 |pages=839–844 |doi=10.1038/s41561-022-01034-w |bibcode=2022NatGe..15..839S |s2cid=252697822 |url=https://www.nature.com/articles/s41561-022-01034-w |access-date=20 April 2023|url-access=subscription }}</ref> Recent research shows that different groups became extinct at different times; for example, while difficult to date absolutely, [[ostracod]] and [[brachiopod]] extinctions were separated by around 670,000 to 1.17 million years.<ref name=Wang2007>{{cite journal |vauthors=Wang SC, Everson PJ |year=2007 |title=Confidence intervals for pulsed mass extinction events |journal=[[Paleobiology (journal)|Paleobiology]] |volume=33 |issue=2 |pages=324–336 |doi=10.1666/06056.1 |bibcode=2007Pbio...33..324W |s2cid=2729020 |url=http://www.swarthmore.edu/NatSci/swang1/Publications/ }}</ref> Paleoenvironmental analysis of [[Lopingian]] strata in the [[Bowen Basin]] of [[Queensland]] indicates numerous intermittent periods of marine environmental stress from the middle to late Lopingian leading up to the end-Permian extinction proper, supporting aspects of the gradualist hypothesis.<ref>{{cite journal |last1=Fielding |first1=Christopher R. |last2=Frank |first2=Tracy D. |last3=Savatic |first3=Katarina |last4=Mays |first4=Chris |last5=McLoughlin |first5=Stephen |last6=Vajda |first6=Vivi |last7=Nicoll |first7=Robert S. |date=15 May 2022 |title=Environmental change in the late Permian of Queensland, NE Australia: The warmup to the end-Permian Extinction |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=594 |page=110936 |doi=10.1016/j.palaeo.2022.110936 |bibcode=2022PPP...59410936F |s2cid=247514266 |doi-access=free }}</ref> Additionally, the decline in marine species richness and the structural collapse of marine ecosystems may have been decoupled as well, with the former preceding the latter by about 61,000 years according to one study.<ref>{{cite journal |last1=Huang |first1=Yuangeng |last2=Chen |first2=Zhong-Qiang |last3=Roopnarine |first3=Peter D. |last4=Benton |first4=Michael James |last5=Zhao |first5=Laishi |last6=Feng |first6=Xueqian |last7=Li |first7=Zhenhua |date=24 February 2023 |title=The stability and collapse of marine ecosystems during the Permian-Triassic mass extinction |journal=[[Current Biology]] |volume=33 |issue=6 |pages=1059–1070.e4 |doi=10.1016/j.cub.2023.02.007 |pmid=36841237 |s2cid=257186215 |doi-access=free |bibcode=2023CBio...33E1059H }}</ref>

Whether the terrestrial and marine extinctions were synchronous or asynchronous is another point of controversy. Evidence from a well-preserved sequence in east [[Greenland]] suggests that the terrestrial and marine extinctions began simultaneously. In this sequence, the decline of animal life is concentrated in a period approximately 10,000 to 60,000 years long, with plants taking an additional several hundred thousand years to show the full impact of the event.<ref name=Twitchett/> Many sedimentary sequences from South China show synchronous terrestrial and marine extinctions.<ref>{{cite journal |last1=Shen |first1=Shu-Zhong |last2=Crowley |first2=James L. |last3=Wang |first3=Yue |last4=Bowring |first4=Samuel R. |last5=Erwin |first5=Douglas H. |last6=Sadler |first6=Peter M. |last7=Cao |first7=Chang-Qun |last8=Rothman |first8=Daniel H. |last9=Henderson |first9=Charles M. |last10=Ramezani |first10=Jahandar |last11=Zhang |first11=Hua |last12=Shen |first12=Yanan |last13=Wang |first13=Xiang-Dong |last14=Wang |first14=Wei |last15=Mu |first15=Lin |last16=Li |first16=Wen-Zhong |last17=Tang |first17=Yue-Gang |last18=Liu |first18=Xiao-Lei |last19=Liu |first19=Lu-Jun |last20=Zeng |first20=Yong |last21=Jiang |first21=Yao-Fa |last22=Jin |first22=Yu-Gan |display-authors=6 |date=17 November 2011 |title=Calibrating the End-Permian Mass Extinction |url=https://www.science.org/doi/10.1126/science.1213454 |journal=[[Science (journal)|Science]] |volume=334 |issue=6061 |pages=1367–1372 |doi=10.1126/science.1213454 |pmid=22096103 |bibcode=2011Sci...334.1367S |s2cid=970244 |access-date=26 May 2023|url-access=subscription }}</ref> Research in the Sydney Basin of the PTME's duration and course also supports a synchronous occurrence of the terrestrial and marine biotic collapses.<ref>{{cite journal |last1=Metcalfe |first1=I. |last2=Crowley |first2=J. L. |last3=Nicoll |first3=Robert S. |last4=Schmitz |first4=M. |date=August 2015 |title=High-precision U-Pb CA-TIMS calibration of Middle Permian to Lower Triassic sequences, mass extinction and extreme climate-change in eastern Australian Gondwana |url=https://www.sciencedirect.com/science/article/abs/pii/S1342937X14002706 |journal=[[Gondwana Research]] |volume=28 |issue=1 |pages=61–81 |doi=10.1016/j.gr.2014.09.002 |bibcode=2015GondR..28...61M |access-date=31 May 2023|url-access=subscription }}</ref> Other scientists believe the terrestrial mass extinction began between 60,000 and 370,000 years before the onset of the marine mass extinction.<ref name=":1">{{cite journal |last1=Dal Corso |first1=Jacopo |last2=Song |first2=Haijun |last3=Callegaro |first3=Sara |last4=Chu |first4=Daoliang |last5=Sun |first5=Yadong |last6=Hilton |first6=Jason |last7=Grasby |first7=Stephen E. |last8=Joachimski |first8=Michael M. |last9=Wignall |first9=Paul Barry |display-authors=6 |date=22 February 2022 |title=Environmental crises at the Permian–Triassic mass extinction |url=https://www.nature.com/articles/s43017-021-00259-4?error=cookies_not_supported&code=48160b3b-7577-4262-bb2b-cb65f64cc2a0 |journal=[[Nature Reviews Earth & Environment]] |volume=3 |issue=3 |pages=197–214 |bibcode=2022NRvEE...3..197D |doi=10.1038/s43017-021-00259-4 |s2cid=247013868 |access-date=20 December 2022 |quote="overwhelming data support that the [Permian-Triassic mass extinction] was triggered by the eruption of the [Siberian Traps Large Igneous Province]." |hdl-access=free |hdl=10852/100010}}</ref><ref>{{Cite journal |last1=Chen |first1=Zhong-Qiang |last2=Harper |first2=David A. T. |last3=Grasby |first3=Stephen |last4=Zhang |first4=Lei |date=1 August 2022 |title=Catastrophic event sequences across the Permian-Triassic boundary in the ocean and on land |url=https://www.sciencedirect.com/science/article/pii/S0921818122001576 |journal=[[Global and Planetary Change]] |volume=215 |pages=103890 |doi=10.1016/j.gloplacha.2022.103890 |bibcode=2022GPC...21503890C |s2cid=250417358 |issn=0921-8181 |access-date=24 November 2023|url-access=subscription }}</ref> Chemostratigraphic analysis from sections in [[Finnmark]] and [[Trøndelag]] shows the terrestrial floral turnover occurred before the large negative δ<sup>13</sup>C shift during the marine extinction.<ref>{{cite journal |last1=Hermann |first1=Elke |last2=Hochuli |first2=Peter A. |last3=Bucher |first3=Hugo |last4=Vigran |first4=Jorunn O. |last5=Weissert |first5=Helmut |last6=Bernasconi |first6=Stefano M. |date=December 2010 |title=A close-up view of the Permian–Triassic boundary based on expanded organic carbon isotope records from Norway (Trøndelag and Finnmark Platform) |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818110002316 |journal=[[Global and Planetary Change]] |volume=74 |issue=3–4 |pages=156–167 |doi=10.1016/j.gloplacha.2010.10.007 |bibcode=2010GPC....74..156H |access-date=10 August 2023|url-access=subscription }}</ref> Dating of the boundary between the ''Dicynodon'' and ''Lystrosaurus'' assemblage zones in the Karoo Basin indicates that the terrestrial extinction occurred earlier than the marine extinction.<ref>{{cite journal |last1=Gastaldo |first1=Robert A. |last2=Kamo |first2=Sandra L. |last3=Neveling |first3=Johann |last4=Geissman |first4=John W. |last5=Bamford |first5=Marion |last6=Looy |first6=Cindy V. |date=1 October 2015 |title=Is the vertebrate-defined Permian-Triassic boundary in the Karoo Basin, South Africa, the terrestrial expression of the end-Permian marine event? |journal=[[Geology (journal)|Geology]] |volume=43 |issue=10 |pages=939–942 |doi=10.1130/G37040.1 |bibcode=2015Geo....43..939G |s2cid=129258297 |doi-access=free }}</ref> The Sunjiagou Formation of South China also records a terrestrial ecosystem demise predating the marine crisis.<ref>{{cite journal |last1=Zhang |first1=Peixin |last2=Yang |first2=Minfang |last3=Lu |first3=Jing |last4=Bond |first4=David P. G. |last5=Zhou |first5=Kai |last6=Xu |first6=Xiaotao |last7=Wang |first7=Ye |last8=He |first8=Zhen |last9=Bian |first9=Xiao |last10=Shao |first10=Longyi |last11=Hilton |first11=Jason |display-authors=6 |date=March 2023 |title=End-Permian terrestrial ecosystem collapse in North China: Evidence from palynology and geochemistry |journal=[[Global and Planetary Change]] |volume=222 |page=104070 |doi=10.1016/j.gloplacha.2023.104070 |bibcode=2023GPC...22204070Z |s2cid=256920630 |doi-access=free }}</ref> Other research still has found that the terrestrial extinction occurred after the marine extinction in the tropics.<ref>{{Cite journal |last1=Wu |first1=Qiong |last2=Zhang |first2=Hua |last3=Ramezani |first3=Jahandar |last4=Zhang |first4=Fei-fei |last5=Erwin |first5=Douglas H. |last6=Feng |first6=Zhuo |last7=Shao |first7=Long-yi |last8=Cai |first8=Yao-feng |last9=Zhang |first9=Shu-han |last10=Xu |first10=Yi-gang |last11=Shen |first11=Shu-zhong |date=2 February 2024 |title=The terrestrial end-Permian mass extinction in the paleotropics postdates the marine extinction |journal=[[Science Advances]] |language=en |volume=10 |issue=5 |pages=eadi7284 |doi=10.1126/sciadv.adi7284 |issn=2375-2548 |pmc=10830061 |pmid=38295161 |bibcode=2024SciA...10I7284W }}</ref>

Studies of the timing and causes of the Permian-Triassic extinction are complicated by the often-overlooked [[Capitanian mass extinction event|Capitanian extinction]] (also called the Guadalupian extinction), just one of perhaps two mass extinctions in the late [[Permian]] that closely preceded the Permian-Triassic event. In short, when the Permian-Triassic starts it is difficult to know whether the end-Capitanian had finished, depending on the factor considered.<ref name=Rohde-Muller2005>{{cite journal |vauthors=Rohde RA, Muller, RA |name-list-style=amp |year=2005 |title=Cycles in fossil diversity |url=https://www.nature.com/articles/nature03339 |journal=[[Nature (journal)|Nature]] |volume=434 |issue=7030 |pages=209–210 |doi=10.1038/nature03339 |pmid=15758998 |bibcode=2005Natur.434..208R |s2cid=32520208 |access-date=14 January 2023|url-access=subscription }}</ref><ref name=Bond-Wignall-etal-2010>{{cite journal |vauthors=Bond DP, Wignall PB, Wang W, Izon G, Jiang HS, Lai XL, Sund YD, Newtona RJ, Shaoe LY, Védrinea S, Cope H |display-authors=6 |year=2010 |title=The mid-Capitanian (Middle Permian) mass extinction and carbon isotope record of South China |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=292 |issue=1–2 |pages=282–294 |doi=10.1016/j.palaeo.2010.03.056|bibcode=2010PPP...292..282B |url=https://hull-repository.worktribe.com/output/423949 }}</ref> Many of the extinctions once dated to the Permian-Triassic boundary have more recently been re-dated to the end-[[Capitanian]]. Further, it is unclear whether some species who survived the prior extinction(s) had recovered well enough for their final demise in the Permian-Triassic event to be considered separate from Capitanian event. A minority point of view considers the sequence of environmental disasters to have effectively constituted a single, prolonged extinction event, perhaps depending on which species is considered. This older theory, still supported in some recent papers,<ref name=SahneyBenton2008RecoveryFromProfoundExtinction/><ref name=Retallack2006>{{cite journal |vauthors=Retallack GJ, Metzger CA, Greaver T, Jahren AH, Smith RM, Sheldon ND |date=November–December 2006 |title=Middle-Late Permian mass extinction on land |journal=[[Bulletin of the Geological Society of America]] |volume=118 |issue=11–12 |pages=1398–1411 |doi=10.1130/B26011.1 |bibcode=2006GSAB..118.1398R}}</ref> proposes that there were two major extinction pulses 9.4 million years apart, separated by a period of extinctions that were less extensive, but still well above the background level, and that the final extinction killed off only about 80% of marine species alive at that time, whereas the other losses occurred during the first pulse or the interval between pulses. According to this theory, one of these extinction pulses occurred at the end of the [[Guadalupian]] [[Epoch (geology)|epoch]] of the Permian.<ref>{{cite arXiv |last=Li |first=Dirson Jian |date=18 December 2012 |title=Tectonic cause of mass extinctions and the genomic contribution to biodiversification |class=q-bio.PE |eprint = 1212.4229}}</ref><ref name=SahneyBenton2008RecoveryFromProfoundExtinction/><ref>{{cite journal |vauthors=Stanley SM, Yang X |year=1994 |title=A double mass extinction at the end of the Paleozoic Era |journal=[[Science (journal)|Science]] |volume=266 |issue=5189 |pages=1340–1344 |doi=10.1126/science.266.5189.1340 |pmid=17772839 |bibcode=1994Sci...266.1340S |s2cid=39256134 }}</ref> For example, all [[dinocephalia]]n genera died out at the end of the Guadalupian,<ref name=Retallack2006/> as did the [[Verbeekinidae]], a family of large-size [[fusulinid|fusuline]] [[foraminifera]].<ref>{{cite journal |vauthors=Ota A, Isozaki Y |date=March 2006 |title=Fusuline biotic turnover across the Guadalupian–Lopingian (Middle–Upper Permian) boundary in mid-oceanic carbonate buildups: Biostratigraphy of accreted limestone in Japan |journal=[[Journal of Asian Earth Sciences]] |volume=26 |issue=3–4 |pages=353–368 |doi=10.1016/j.jseaes.2005.04.001 |bibcode=2006JAESc..26..353O}}</ref> The impact of the end-Guadalupian extinction on marine organisms appears to have varied between locations and between taxonomic groups – brachiopods and [[coral]]s had severe losses.<ref>{{cite journal |vauthors=Shen S, Shi GR |year=2002 |title=Paleobiogeographical extinction patterns of Permian brachiopods in the Asian-western Pacific region |journal=[[Paleobiology (journal)|Paleobiology]] |volume=28 |issue=4 |pages=449–463 |issn=0094-8373 |s2cid=35611701 |doi=10.1666/0094-8373(2002)028<0449:PEPOPB>2.0.CO;2 |bibcode=2002Pbio...28..449S }}</ref><ref>{{cite journal |vauthors=Wang XD, Sugiyama T |date=December 2000 |title=Diversity and extinction patterns of Permian coral faunas of China |journal=[[Lethaia]] |volume=33 |issue=4 |pages=285–294 |doi=10.1080/002411600750053853 |bibcode=2000Letha..33..285W }}</ref>

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