Editing Permian–Triassic extinction event (section)

=== Marine ecosystems ===
[[File:Claraia Clarai Museum Gröden.jpg|thumb|Shell bed with the bivalve ''[[Claraia clarai]]'', a common early Triassic [[disaster taxon]]]]

A cosmopolitanism event began immediately after the end-Permian extinction event.<ref>{{cite journal |last1=Zhang |first1=Shu-han |last2=Shen |first2=Shu-zhong |last3=Erwin |first3=Douglas H. |date=September 2022 |title=Two cosmopolitanism events driven by different extreme paleoclimate regimes |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818122001667 |journal=[[Global and Planetary Change]] |volume=216 |page=103899 |doi=10.1016/j.gloplacha.2022.103899 |bibcode=2022GPC...21603899Z |s2cid=251174662 |access-date=26 May 2023|url-access=subscription }}</ref> Marine post-extinction faunas were mostly species-poor and were dominated by few [[pioneer organism|disaster taxa]] such as the bivalves ''[[Claraia]]'', ''Unionites'', ''Eumorphotis'', and ''Promyalina'',<ref name="PetsiosBottjer2016">{{cite journal |last1=Petsios |first1=Elizabeth |last2=Bottjer |first2=David P. |date=28 April 2016 |title=Quantitative analysis of the ecological dominance of benthic disaster taxa in the aftermath of the end-Permian mass extinction |url=https://pubs.geoscienceworld.org/paleobiol/article-abstract/42/3/380/304922/Quantitative-analysis-of-the-ecological-dominance |journal=[[Paleobiology (journal)|Paleobiology]] |volume=42 |issue=3 |pages=380–393 |doi=10.1017/pab.2015.47 |bibcode=2016Pbio...42..380P |s2cid=88450377 |access-date=23 March 2023|url-access=subscription }}</ref> the conodonts ''[[Clarkina]] and [[Hindeodus]],''<ref>{{Cite journal |last1=Yuan |first1=Dong-Xun |last2=Zhang |first2=Yi-Chun |last3=Shen |first3=Shu-Zhong |date=1 February 2018 |title=Conodont succession and reassessment of major events around the Permian-Triassic boundary at the Selong Xishan section, southern Tibet, China |url=https://www.sciencedirect.com/science/article/pii/S0921818117303624 |journal=[[Global and Planetary Change]] |volume=161 |pages=194–210 |doi=10.1016/j.gloplacha.2017.12.024 |bibcode=2018GPC...161..194Y |issn=0921-8181 |access-date=24 November 2023|url-access=subscription }}</ref> the inarticulate brachiopod ''Lingularia'',<ref name="PetsiosBottjer2016" /> and the foraminifera ''Earlandia'' and ''Rectocornuspira kalhori'',<ref>{{cite journal |last1=Groves |first1=John R. |last2=Rettori |first2=Roberto |last3=Payne |first3=Jonathan L. |last4=Boyce |first4=Matthew D. |last5=Altiner |first5=Demír |date=14 July 2015 |title=End-Permian mass extinction of lagenide foraminifers in the Southern Alps (Northern Italy) |url=https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/endpermian-mass-extinction-of-lagenide-foraminifers-in-the-southern-alps-northern-italy/464BE45FED6C4A2C64B4D3FA9C17141D |journal=[[Journal of Paleontology]] |volume=81 |issue=3 |pages=415–434 |doi=10.1666/05123.1 |hdl=11511/46635 |s2cid=32920409 |access-date=23 March 2023|url-access=subscription }}</ref> the latter of which is sometimes classified under the genus ''[[Ammodiscus]]''.<ref>{{Cite journal |last1=Kolar-Jurkovšek |first1=Tea |last2=Hrvatović |first2=Hazim |last3=Aljinović |first3=Dunja |last4=Nestell |first4=Galina P. |last5=Jurkovšek |first5=Bogdan |last6=Skopljak |first6=Ferid |date=1 May 2021 |title=Permian-Triassic biofacies of the Teočak section, Bosnia and Herzegovina |url=https://www.sciencedirect.com/science/article/pii/S0921818121000436 |journal=[[Global and Planetary Change]] |volume=200 |pages=103458 |doi=10.1016/j.gloplacha.2021.103458 |bibcode=2021GPC...20003458K |s2cid=233858016 |issn=0921-8181 |access-date=24 November 2023|url-access=subscription }}</ref> Their [[guild (ecology)|guild]] diversity was also low.<ref>{{cite journal |last1=Schubert |first1=Jennifer K. |last2=Bottjer |first2=David J. |date=June 1995 |title=Aftermath of the Permian-Triassic mass extinction event: Paleoecology of Lower Triassic carbonates in the western USA |url=https://dx.doi.org/10.1016/0031-0182%2894%2900093-N |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=116 |issue=1–2 |pages=1–39 |doi=10.1016/0031-0182(94)00093-N |bibcode=1995PPP...116....1S |access-date=2 April 2023|url-access=subscription }}</ref> Post-PTME faunas had a flat, insignificant latitudinal diversity gradient.<ref>{{Cite journal |last1=Song |first1=Haijun |last2=Huang |first2=Shan |last3=Jia |first3=Enhao |last4=Dai |first4=Xu |last5=Wignall |first5=Paul Barry |last6=Dunhill |first6=Alexander M. |date=28 July 2020 |title=Flat latitudinal diversity gradient caused by the Permian–Triassic mass extinction |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |language=en |volume=117 |issue=30 |pages=17578–17583 |doi=10.1073/pnas.1918953117 |doi-access=free |issn=0027-8424 |pmc=7395496 |pmid=32631978 |bibcode=2020PNAS..11717578S }}</ref>

The speed of recovery from the extinction is disputed. Some scientists estimate that it took 10&nbsp;million years (until the [[Middle Triassic]]) due to the severity of the extinction.<ref>{{cite news |date=27 May 2012 |title=It took Earth ten million years to recover from greatest mass extinction |url=https://www.sciencedaily.com/releases/2012/05/120527153810.htm |access-date=28 May 2012 |newspaper=ScienceDaily}}</ref> However, studies in [[Bear Lake County, Idaho|Bear Lake County]], near [[Paris, Idaho]],<ref name="Brayard2017">{{cite journal |last1=Brayard |first1=Arnaud |last2=Krumenacker |first2=L. J. |last3=Botting |first3=Joseph P. |last4=Jenks |first4=James F. |last5=Bylund |first5=Kevin G. |last6=Fara |first6=Emmanuel |last7=Vennin |first7=Emmanuelle |last8=Olivier |first8=Nicolas |last9=Goudemand |first9=Nicolas |last10=Saucède |first10=Thomas |last11=Charbonnier |first11=Sylvain |last12=Romano |first12=Carlo |last13=Doguzhaeva |first13=Larisa |last14=Thuy |first14=Ben |last15=Hautmann |first15=Michael |date=15 February 2017 |title=Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna |journal=[[Science Advances]] |volume=13 |issue=2 |pages=e1602159 |bibcode=2017SciA....3E2159B |doi=10.1126/sciadv.1602159 |pmc=5310825 |pmid=28246643 |last16=Stephen |first16=Daniel A. |last17=Thomazo |first17=Christophe |last18=Escarguel |first18=Gilles}}</ref> and nearby sites in Idaho and [[Nevada]]<ref>{{cite journal |last1=Smith |first1=Christopher P. A. |last2=Laville |first2=Thomas |last3=Fara |first3=Emmanuel |last4=Escarguel |first4=Gilles |last5=Olivier |first5=Nicolas |last6=Vennin |first6=Emmanuelle |last7=Goudemand |first7=Nicolas |last8=Bylund |first8=Kevin G. |last9=Jenks |first9=James F. |last10=Stephen |first10=Daniel A. |last11=Hautmann |first11=Michael |last12=Charbonnier |first12=Sylvain |last13=Krumenacker |first13=L. J. |last14=Brayard |first14=Arnaud |display-authors=6 |date=2021-10-04 |title=Exceptional fossil assemblages confirm the existence of complex Early Triassic ecosystems during the early Spathian |journal=[[Scientific Reports]] |volume=11 |issue=1 |page=19657 |bibcode=2021NatSR..1119657S |doi=10.1038/s41598-021-99056-8 |issn=2045-2322 |pmc=8490361 |pmid=34608207}}</ref> showed a relatively quick rebound in a localized [[Early Triassic]] marine ecosystem ([[Paris biota]]), taking around 1.3&nbsp;million years to recover,<ref name="Brayard2017"/> while an unusually diverse and complex [[Trace fossil|ichnobiota]] is known from Italy less than a million years after the end-Permian extinction.<ref>{{cite journal |last1=Hofmann |first1=Richard |last2=Goudemand |first2=Nicolas |last3=Wasmer |first3=Martin |last4=Bucher |first4=Hugo |last5=Hautmann |first5=Michael |date=1 October 2011 |title=New trace fossil evidence for an early recovery signal in the aftermath of the end-Permian mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S003101821100397X |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=310 |issue=3–4 |pages=216–226 |bibcode=2011PPP...310..216H |doi=10.1016/j.palaeo.2011.07.014 |access-date=20 December 2022|url-access=subscription }}</ref> Additionally, the complex [[Guiyang biota]] found near [[Guiyang]], China also indicates life thrived in some places just a million years after the mass extinction,<ref name="natnews-guoyang">{{cite journal |last1=Lewis |first1=Dyani |date=9 February 2023 |title=Sea life bounced back fast after the 'mother of mass extinctions' |url=https://www.nature.com/articles/d41586-023-00383-9 |journal=[[Nature (journal)|Nature]] |doi=10.1038/d41586-023-00383-9 |pmid=36759740 |s2cid=256738043 |access-date=23 February 2023|url-access=subscription }}</ref><ref name="science-guoyang">{{Cite journal |last1=Dai |first1=X. |last2=Davies |first2=J. H. F. L. |last3=Yuan |first3=Z. |last4=Brayard |first4=A. |last5=Ovtcharova |first5=M. |last6=Xu |first6=G. |last7=Liu |first7=X. |last8=Smith |first8=C. P. A. |last9=Schweitzer |first9=C. E. |last10=Li |first10=M. |last11=Perrot |first11=M. G. |last12=Jiang |first12=S. |last13=Miao |first13=L. |last14=Cao |first14=Y. |last15=Yan |first15=J. |year=2023 |title=A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem |url=https://www.science.org/doi/10.1126/science.adf1622 |journal=[[Science (journal)|Science]] |volume=379 |issue=6632 |pages=567–572 |bibcode=2023Sci...379..567D |doi=10.1126/science.adf1622 |pmid=36758082 |s2cid=256697946 |last16=Bai |first16=R. |last17=Wang |first17=F. |last18=Guo |first18=W. |last19=Song |first19=H. |last20=Tian |first20=L. |last21=Dal Corso |first21=J. |last22=Liu |first22=Y. |last23=Chu |first23=D. |last24=Song |first24=H.}}</ref> as does a fossil assemblage known as the Shanggan fauna found in Shanggan, China,<ref>{{cite journal |last1=Hautmann |first1=Michael |last2=Bucher |first2=Hugo |last3=Brühwiler |first3=Thomas |last4=Goudemand |first4=Nicolas |last5=Kaim |first5=Andrzej |last6=Nützel |first6=Alexander |date=January–February 2011 |title=An unusually diverse mollusc fauna from the earliest Triassic of South China and its implications for benthic recovery after the end-Permian biotic crisis |url=https://www.sciencedirect.com/science/article/abs/pii/S0016699510001166 |journal=[[Geobios]] |volume=44 |issue=1 |pages=71–85 |bibcode=2011Geobi..44...71H |doi=10.1016/j.geobios.2010.07.004 |access-date=2 April 2023|url-access=subscription }}</ref> the Wangmo biota from the Luolou Formation of Guizhou,<ref>{{Cite journal |last1=Zhou |first1=C.Y. |last2=Zhang |first2=Q.Y. |last3=Wen |first3=W. |last4=Huang |first4=J.Y. |last5=Hu |first5=S.X. |last6=Liu |first6=W. |last7=Min |first7=X. |last8=Ma |first8=Z.X. |last9=Wen |first9=Q.Q. |year=2024 |title=A new Early Triassic fossil Lagerstätte from Wangmo, Guizhou Province |url=https://www.cgsjournals.com/article/doi/10.19826/j.cnki.1009-3850.2022.06011 |journal=Sedimentary Geology and Tethyan Geology |volume=44 |issue=1 |pages=1–8 |doi=10.19826/j.cnki.1009-3850.2022.06011}}</ref> and a gastropod fauna from the Al Jil Formation of Oman.<ref>{{cite journal |last1=Wheeley |first1=James |last2=Twitchett |first2=Richard J. |date=2 January 2007 |title=Palaeoecological significance of a new Griesbachian (Early Triassic) gastropod assemblage from Oman |url=https://onlinelibrary.wiley.com/doi/abs/10.1080/0024116051003150 |journal=[[Lethaia]] |volume=38 |issue=1 |pages=37–45 |doi=10.1080/0024116051003150 |access-date=8 April 2023|url-access=subscription }}</ref> Regional differences in the pace of biotic recovery existed,<ref>{{Cite journal |last1=Pruss |first1=Sara B. |last2=Bottjer |first2=David J. |date=1 December 2004 |title=Early Triassic Trace Fossils of the Western United States and their Implications for Prolonged Environmental Stress from the End-Permian Mass Extinction |url=https://pubs.geoscienceworld.org/palaios/article/19/6/551-564/99969 |journal=[[PALAIOS]] |language=en |volume=19 |issue=6 |pages=551–564 |doi=10.1669/0883-1351(2004)019<0551:ETTFOT>2.0.CO;2 |bibcode=2004Palai..19..551P |issn=0883-1351 |access-date=18 June 2024 |via=GeoScienceWorld|url-access=subscription }}</ref><ref>{{Cite journal |last1=Flannery-Sutherland |first1=Joseph T. |last2=Silvestro |first2=Daniele |last3=Benton |first3=Michael J. |date=18 May 2022 |title=Global diversity dynamics in the fossil record are regionally heterogeneous |journal=[[Nature Communications]] |language=en |volume=13 |issue=1 |page=2751 |doi=10.1038/s41467-022-30507-0 |issn=2041-1723 |pmc=9117201 |pmid=35585069 |bibcode=2022NatCo..13.2751F }}</ref> which suggests that the impact of the extinction may have been felt less severely in some areas than others, with differential environmental stress and instability being the source of the variance.<ref>{{Cite journal |last1=Woods |first1=Adam D. |last2=Bottjer |first2=David J. |last3=Mutti |first3=Maria |last4=Morrison |first4=Jean |date=1 July 1999 |title=Lower Triassic large sea-floor carbonate cements: Their origin and a mechanism for the prolonged biotic recovery from the end-Permian mass extinction |url=https://pubs.geoscienceworld.org/geology/article/27/7/645-648/189532 |journal=[[Geology (journal)|Geology]] |language=en |volume=27 |issue=7 |pages=645–648 |doi=10.1130/0091-7613(1999)027<0645:LTLSFC>2.3.CO;2 |bibcode=1999Geo....27..645W |issn=0091-7613 |access-date=24 November 2023|url-access=subscription }}</ref><ref name="WoodsAlmsMonarrezMata2019">{{cite journal |last1=Woods |first1=Adam D. |last2=Alms |first2=Paul D. |last3=Monarrez |first3=Pedro M. |last4=Mata |first4=Scott |date=1 January 2019 |title=The interaction of recovery and environmental conditions: An analysis of the outer shelf edge of western North America during the early Triassic |url=https://www.sciencedirect.com/science/article/abs/pii/S003101821730696X |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=513 |pages=52–64 |bibcode=2019PPP...513...52W |doi=10.1016/j.palaeo.2018.05.014 |access-date=20 December 2022|url-access=subscription }}</ref> In addition, it has been proposed that although overall taxonomic diversity rebounded rapidly, functional ecological diversity took much longer to return to its pre-extinction levels;<ref>{{cite journal |last1=Dineen |first1=Ashley M. |last2=Fraiser |first2=Margaret L. |last3=Sheehan |first3=Peter M. |date=September 2014 |title=Quantifying functional diversity in pre- and post-extinction paleocommunities: A test of ecological restructuring after the end-Permian mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S001282521400110X |journal=[[Earth-Science Reviews]] |volume=136 |pages=339–349 |bibcode=2014ESRv..136..339D |doi=10.1016/j.earscirev.2014.06.002 |access-date=2 April 2023|url-access=subscription }}</ref> one study concluded that marine ecological recovery was still ongoing 50 million years after the extinction, during the latest Triassic, even though taxonomic diversity had rebounded in a tenth of that time.<ref>{{cite journal |last1=Song |first1=Haijun |last2=Wignall |first2=Paul Barry |last3=Dunhill |first3=Alexander M. |date=10 October 2018 |title=Decoupled taxonomic and ecological recoveries from the Permo-Triassic extinction |journal=[[Science Advances]] |volume=4 |issue=10 |pages=eaat5091 |bibcode=2018SciA....4.5091S |doi=10.1126/sciadv.aat5091 |pmc=6179380 |pmid=30324133}}</ref>

The pace and timing of recovery also differed based on clade and mode of life. Seafloor communities maintained a comparatively low diversity until the end of the Early Triassic, approximately 4&nbsp;million years after the extinction event.<ref name="Hofmann et al. 2014">{{cite journal |last1=Hofmann |first1=Richard |last2=Hautmann |first2=Michael |last3=Brayard |first3=Arnaud |last4=Nützel |first4=Alexander |last5=Bylund |first5=Kevin G. |last6=Jenks |first6=James F. |last7=Vennin |first7=Emmanuelle |last8=Olivier |first8=Nicolas |last9=Bucher |first9=Hugo |last10=Sevastopulo |first10=George |display-authors=6 |date=May 2014 |title=Recovery of benthic marine communities from the end-Permian mass extinction at the low latitudes of eastern Panthalassa |url=https://www.zora.uzh.ch/id/eprint/84501/1/Hofmann_etal_2014_recovery-USA_PALAEO-4.pdf |journal=[[Palaeontology (journal)|Palaeontology]] |volume=57 |issue=3 |pages=547–589 |bibcode=2014Palgy..57..547H |doi=10.1111/pala.12076 |s2cid=6247479}}</ref> Epifaunal benthos took longer to recover than infaunal benthos.<ref>{{cite journal |last1=Feng |first1=Xueqian |last2=Chen |first2=Zhong-Qiang |last3=Benton |first3=Michael James |last4=Su |first4=Chunmei |last5=Bottjer |first5=David J. |last6=Cribb |first6=Alison T. |last7=Li |first7=Ziheng |last8=Zhao |first8=Liashi |last9=Zhu |first9=Guangyou |last10=Huang |first10=Yuangeng |last11=Guo |first11=Zhen |date=29 June 2022 |title=Resilience of infaunal ecosystems during the Early Triassic greenhouse Earth |journal=[[Science Advances]] |volume=8 |issue=26 |pages=eabo0597 |bibcode=2022SciA....8O.597F |doi=10.1126/sciadv.abo0597 |pmc=9242451 |pmid=35767613 |s2cid=250114146}}</ref> This slow recovery stands in remarkable contrast with the quick recovery seen in nektonic organisms such as [[ammonoids]], which exceeded pre-extinction diversities already two million years after the crisis,<ref>{{cite journal |last1=Brayard |first1=A. |last2=Escarguel |first2=G. |last3=Bucher |first3=H. |last4=Monnet |first4=C. |last5=Bruhwiler |first5=T. |last6=Goudemand |first6=N. |last7=Galfetti |first7=T. |last8=Guex |first8=J. |display-authors=6 |date=27 August 2009 |title=Good genes and good luck: Ammonoid diversity and the end-Permian mass extinction |journal=[[Science (journal)|Science]] |volume=325 |issue=5944 |pages=1118–1121 |bibcode=2009Sci...325.1118B |doi=10.1126/science.1174638 |pmid=19713525 |s2cid=1287762}}</ref> and conodonts, which diversified considerably over the first two million years of the Early Triassic.<ref>{{cite journal |last1=Chen |first1=Zhong-Qiang |last2=Benton |first2=Michael James |date=27 May 2012 |title=The timing and pattern of biotic recovery following the end-Permian mass extinction |url=https://www.nature.com/articles/ngeo1475?error=cookies_not_supported&code=5176d851-7a2b-46f4-a0bc-070091275f15 |journal=[[Nature Geoscience]] |volume=5 |issue=6 |pages=375–383 |bibcode=2012NatGe...5..375C |doi=10.1038/ngeo1475 |access-date=28 March 2023|url-access=subscription }}</ref>

Recent work suggests that the pace of recovery was intrinsically driven by the intensity of competition among species, which drives rates of [[niche differentiation]] and [[speciation]].<ref name="Hautmann et al. 2015">{{cite journal |last1=Hautmann |first1=Michael |last2=Bagherpour |first2=Borhan |last3=Brosse |first3=Morgane |last4=Frisk |first4=Åsa |last5=Hofmann |first5=Richard |last6=Baud |first6=Aymon |last7=Nützel |first7=Alexander |last8=Goudemand |first8=Nicolas |last9=Bucher |first9=Hugo |last10=Brayard |first10=Arnaud |display-authors=6 |title=Competition in slow motion: The unusual case of benthic marine communities in the wake of the end-Permian mass extinction |journal=[[Palaeontology (journal)|Palaeontology]] |date=September 2015 |volume=58 |issue=5 |pages=871–901 |doi=10.1111/pala.12186|bibcode=2015Palgy..58..871H |s2cid=140688908 |doi-access=free }}</ref> That recovery was slow in the Early Triassic can be explained by low levels of biological competition due to the paucity of taxonomic diversity,<ref name="GrosseEtAl2018">{{cite journal |last1=Grosse |first1=Morgane |last2=Bucher |first2=Hugo |last3=Baud |first3=Aymon |last4=Frisk |first4=Åsa M. |last5=Goudemand |first5=Nicolas |last6=Hagdorn |first6=Hans |last7=Nützel |first7=Alexander |last8=Ware |first8=David |last9=Hautmann |first9=Michael |date=31 July 2018 |title=New data from Oman indicate benthic high biomass productivity coupled with low taxonomic diversity in the aftermath of the Permian–Triassic Boundary mass extinction |url=https://onlinelibrary.wiley.com/doi/full/10.1111/let.12281 |journal=[[Lethaia]] |volume=52 |issue=2 |pages=165–187 |doi=10.1111/let.12281 |s2cid=135442906 |access-date=8 April 2023|url-access=subscription }}</ref> and that biotic recovery explosively accelerated in the Anisian can be explained by niche crowding, a phenomenon that would have drastically increased competition, becoming prevalent by the Anisian.<ref>{{cite journal |last1=Friesenbichler |first1=Evelyn |last2=Hautmann |first2=Michael |last3=Bucher |first3=Hugo |date=20 July 2021 |title=The main stage of recovery after the end-Permian mass extinction: taxonomic rediversification and ecologic reorganization of marine level-bottom communities during the Middle Triassic |journal=[[PeerJ]] |volume=9 |pages=e11654 |doi=10.7717/peerj.11654 |pmid=34322318 |pmc=8300500 |doi-access=free }}</ref> Biodiversity rise thus behaved as a positive feedback loop enhancing itself as it took off in the Spathian and Anisian.<ref>{{cite journal |last1=Erwin |first1=Douglas H. |date=January–September 2007 |title=Increasing returns, ecological feedback and the Early Triassic recovery |url=https://www.sciencedirect.com/science/article/abs/pii/S1871174X07000054 |journal=[[Palaeoworld]] |volume=16 |issue=1–3 |pages=9–15 |doi=10.1016/j.palwor.2007.05.013 |access-date=3 July 2023|url-access=subscription }}</ref> Accordingly, low levels of [[interspecific competition]] in seafloor communities that are dominated by [[primary consumers]] correspond to slow rates of [[Genetic divergence|diversification]] and high levels of interspecific competition among nektonic secondary and tertiary consumers to high diversification rates.<ref name="GrosseEtAl2018" /> Other explanations state that life was delayed in its recovery because grim conditions returned periodically over the course of the Early Triassic,<ref>{{Cite journal |last1=Wei |first1=Hengye |last2=Shen |first2=Jun |last3=Schoepfer |first3=Shane D. |last4=Krystyn |first4=Leo |last5=Richoz |first5=Sylvain |last6=Algeo |first6=Thomas J. |date=October 2015 |title=Environmental controls on marine ecosystem recovery following mass extinctions, with an example from the Early Triassic |url=https://linkinghub.elsevier.com/retrieve/pii/S001282521400186X |journal=[[Earth-Science Reviews]] |language=en |volume=149 |pages=108–135 |doi=10.1016/j.earscirev.2014.10.007 |bibcode=2015ESRv..149..108W |access-date=18 June 2024 |via=Elsevier Science Direct}}</ref><ref>{{cite journal |last1=Stanley |first1=Steven M. |date=8 September 2009 |title=Evidence from ammonoids and conodonts for multiple Early Triassic mass extinctions |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=106 |issue=36 |pages=15264–15267 |bibcode=2009PNAS..10615264S |doi=10.1073/pnas.0907992106 |pmc=2741239 |pmid=19721005 |doi-access=free}}</ref> causing further extinction events, such as the [[Smithian-Spathian boundary extinction]].<ref name="ChenRichoz2019" /><ref>{{Cite journal |last1=Sun |first1=Y. D. |last2=Wignall |first2=Paul Barry |last3=Joachimski |first3=Michael M. |last4=Bond |first4=David P. G. |last5=Grasby |first5=Stephen E. |last6=Sun |first6=S. |last7=Yan |first7=C. B. |last8=Wang |first8=L. N. |last9=Chen |first9=Y. L. |last10=Lai |first10=X. L. |date=1 June 2015 |title=High amplitude redox changes in the late Early Triassic of South China and the Smithian–Spathian extinction |url=https://www.sciencedirect.com/science/article/pii/S0031018215001698 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=427 |pages=62–78 |doi=10.1016/j.palaeo.2015.03.038 |bibcode=2015PPP...427...62S |issn=0031-0182 |access-date=24 November 2023}}</ref><ref>{{Cite journal |last1=Lloret |first1=Joan |last2=De la Horra |first2=Raúl |last3=Gretter |first3=Nicola |last4=Borruel-Abadía |first4=Violeta |last5=Barrenechea |first5=José F. |last6=Ronchi |first6=Ausonio |last7=Diez |first7=José B. |last8=Arche |first8=Alfredo |last9=López-Gómez |first9=José |date=1 September 2020 |title=Gradual changes in the Olenekian-Anisian continental record and biotic implications in the Central-Eastern Pyrenean basin, NE Spain |url=https://www.sciencedirect.com/science/article/pii/S0921818120301430 |journal=[[Global and Planetary Change]] |volume=192 |pages=103252 |doi=10.1016/j.gloplacha.2020.103252 |bibcode=2020GPC...19203252L |s2cid=225301237 |issn=0921-8181 |access-date=24 November 2023|url-access=subscription }}</ref> Continual episodes of extremely hot climatic conditions during the Early Triassic have been held responsible for the delayed recovery of oceanic life,<ref name="PetsiosEtAl2019">{{cite journal |last1=Petsios |first1=Elizabeth |last2=Thompson |first2=Jeffrey R. |last3=Pietsch |first3=Carlie |last4=Bottjer |first4=David J. |date=1 January 2019 |title=Biotic impacts of temperature before, during, and after the end-Permian extinction: A multi-metric and multi-scale approach to modeling extinction and recovery dynamics |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217306223 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=513 |pages=86–99 |doi=10.1016/j.palaeo.2017.08.038 |bibcode=2019PPP...513...86P |s2cid=134149088 |access-date=2 December 2022|url-access=subscription }}</ref><ref name="EnhancedReverseWeathering">{{cite journal |last1=Cao |first1=Cheng |last2=Bataille |first2=Clément P. |last3=Song |first3=Haijun |last4=Saltzman |first4=Matthew R. |last5=Cramer |first5=Kate Tierney |last6=Wu |first6=Huaichun |last7=Korte |first7=Christoph |last8=Zhang |first8=Zhaofeng |last9=Liu |first9=Xiao-Ming |date=3 October 2022 |title=Persistent late Permian to Early Triassic warmth linked to enhanced reverse weathering |url=https://www.researchgate.net/publication/364124531 |journal=[[Nature Geoscience]] |volume=15 |issue=1 |pages=832–838 |doi=10.1038/s41561-022-01009-x |bibcode=2022NatGe..15..832C |s2cid=252708876 |access-date=20 April 2023}}</ref> in particular skeletonized taxa that are most vulnerable to high carbon dioxide concentrations.<ref>{{cite journal |last1=Wood |first1=Rachel |last2=Erwin |first2=Douglas H. |date=16 October 2017 |title=Innovation not recovery: dynamic redox promotes metazoan radiations |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12375 |journal=Biology Reviews |volume=93 |issue=2 |pages=863–873 |doi=10.1111/brv.12375 |pmid=29034568 |hdl=20.500.11820/a962bbdd-5d2a-45f9-8cbf-2fdd1d539ba1 |s2cid=207103048 |access-date=20 April 2023|hdl-access=free }}</ref> The relative delay in the recovery of benthic organisms has been attributed to widespread anoxia,<ref name="OceanicAnoxiaAndTheEndPermianMassExtinction">{{cite journal |last1=Wignall |first1=P. B. |last2=Twitchett |first2=Richard J. |date=24 May 1996 |title=Oceanic Anoxia and the End Permian Mass Extinction |journal=[[Science (journal)|Science]] |volume=272 |issue=5265 |pages=1155–1158 |bibcode=1996Sci...272.1155W |doi=10.1126/science.272.5265.1155 |pmid=8662450 |s2cid=35032406}}</ref> but high abundances of benthic species contradict this explanation.<ref>{{cite journal |last1=Hofmann |first1=Richard |last2=Hautmann |first2=Michael |last3=Bucher |first3=Hugo |date=October 2015 |title=Recovery dynamics of benthic marine communities from the Lower Triassic Werfen Formation, northern Italy |journal=[[Lethaia]] |volume=48 |issue=4 |pages=474–496 |doi=10.1111/let.12121|bibcode=2015Letha..48..474H }}</ref> A 2019 study attributed the dissimilarity of recovery times between different ecological communities to differences in local environmental stress during the biotic recovery interval, with regions experiencing persistent environmental stress post-extinction recovering more slowly, supporting the view that recurrent environmental calamities were culpable for retarded biotic recovery.<ref name="WoodsAlmsMonarrezMata2019" /> Recurrent Early Triassic environmental stresses also acted as a ceiling limiting the maximum ecological complexity of marine ecosystems until the Spathian.<ref>{{cite journal |last1=Foster |first1=William J. |last2=Danise |first2=Silvia |last3=Price |first3=Gregory D. |last4=Twitchett |first4=Richard J. |date=15 March 2017 |title=Subsequent biotic crises delayed marine recovery following the late Permian mass extinction event in northern Italy |journal=[[PLOS ONE]] |volume=12 |issue=3 |pages=e0172321 |doi=10.1371/journal.pone.0172321 |pmid=28296886 |pmc=5351997 |bibcode=2017PLoSO..1272321F |doi-access=free }}</ref> Recovery biotas appear to have been ecologically uneven and unstable into the [[Anisian]], making them vulnerable to environmental stresses.<ref>{{cite journal |last1=Dineen |first1=Ashley A. |last2=Fraiser |first2=Margaret L. |last3=Tong |first3=Jinnan |date=October 2015 |title=Low functional evenness in a post-extinction Anisian (Middle Triassic) paleocommunity: A case study of the Leidapo Member (Qingyan Formation), south China |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818115001502 |journal=[[Global and Planetary Change]] |volume=133 |pages=79–86 |doi=10.1016/j.gloplacha.2015.08.001 |bibcode=2015GPC...133...79D |access-date=2 April 2023|url-access=subscription }}</ref>

Whereas most marine communities were fully recovered by the Middle Triassic,<ref>{{cite journal |last1=Friesenbichler |first1=Evelyn |last2=Hautmann |first2=Michael |last3=Nützel |first3=Alexander |last4=Urlichs |first4=Max |last5=Bucher |first5=Hugo |title=Palaeoecology of Late Ladinian (Middle Triassic) benthic faunas from the Schlern/Sciliar and Seiser Alm/Alpe di Siusi area (South Tyrol, Italy) |journal=[[PalZ]] |date=24 July 2018 |volume=93 |issue=1 |pages=1–29 |doi=10.1007/s12542-018-0423-7 |s2cid=134192673 |url=https://www.zora.uzh.ch/id/eprint/152680/9/PAZE-D-17-00052_R2.pdf }}</ref><ref>{{cite journal |last1=Friesenbichler |first1=Evelyn |last2=Hautmann |first2=Michael |last3=Grădinaru |first3=Eugen |last4=Bucher |first4=Hugo |last5=Brayard |first5=Arnaud |title=A highly diverse bivalve fauna from a Bithynian (Anisian, Middle Triassic) – microbial buildup in North Dobrogea (Romania) |journal=Papers in Palaeontology |date=12 October 2019 |doi=10.1002/spp2.1286|s2cid=208555999 |url=https://www.zora.uzh.ch/id/eprint/175886/3/_system_appendPDF_proof_hi-1.pdf }}</ref> global marine diversity reached pre-extinction values no earlier than the Middle Jurassic, approximately 75&nbsp;million years after the extinction event.<ref name="Sepkoski 1997">{{cite journal |last1=Sepkoski |first1=J. John |title=Biodiversity: Past, Present, and Future |journal=[[Journal of Paleontology]] |date=1997 |volume=71 |issue=4 |pages=533–539 |doi=10.1017/S0022336000040026|pmid=11540302 |bibcode=1997JPal...71..533S |s2cid=27430390 }}</ref>

[[File:Crinoïde Carbonifère 8127.jpg| thumb | left | Sessile filter feeders like this [[Carboniferous]] crinoid, the mushroom crinoid (''[[Agaricocrinus americanus]]''), were significantly less abundant after the P–Tr extinction.]]
Prior to the extinction, about two-thirds of marine animals were [[sessility (zoology)|sessile]] and attached to the seafloor. During the Mesozoic, only about half of the marine animals were sessile while the rest were free-living. Analysis of marine fossils from the period indicated a decrease in the abundance of sessile [[epifauna]]l [[suspension feeder]]s such as brachiopods and [[sea lily|sea lilies]] and an increase in more complex mobile species such as [[snail]]s, [[sea urchins]] and [[crab]]s.<ref name="WagnerKosnikLidgard2006" /> Before the Permian mass extinction event, both complex and simple marine ecosystems were equally common. After the recovery from the mass extinction, the complex communities outnumbered the simple communities by nearly three to one,<ref name="WagnerKosnikLidgard2006">{{cite journal|title=Abundance Distributions Imply Elevated Complexity of Post-Paleozoic Marine Ecosystems|vauthors=Wagner PJ, Kosnik MA, Lidgard S |journal=[[Science (journal)|Science]]|year=2006|volume=314|issue=5803|pages=1289–1292|doi=10.1126/science.1133795|pmid=17124319
|bibcode = 2006Sci...314.1289W |s2cid=26957610 }}</ref> and the increase in predation pressure and durophagy led to the [[Mesozoic Marine Revolution]].<ref>{{Cite journal |last1=Salamon |first1=Mariusz A. |last2=Niedźwiedzki |first2=Robert |last3=Gorzelak |first3=Przemysław |last4=Lach |first4=Rafał |last5=Surmik |first5=Dawid |date=1 March 2012 |title=Bromalites from the Middle Triassic of Poland and the rise of the Mesozoic Marine Revolution |url=https://linkinghub.elsevier.com/retrieve/pii/S0031018212000533 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=321-322 |pages=142–150 |doi=10.1016/j.palaeo.2012.01.029 |bibcode=2012PPP...321..142S |access-date=24 November 2023|url-access=subscription }}</ref>

Marine vertebrates recovered relatively quickly, with complex predator-prey interactions with vertebrates at the top of the food web being known from coprolites five million years after the PTME.<ref>{{Cite journal |last1=Nakajima |first1=Yasuhisa |last2=Izumi |first2=Kentaro |date=15 November 2014 |title=Coprolites from the upper Osawa Formation (upper Spathian), northeastern Japan: Evidence for predation in a marine ecosystem 5Myr after the end-Permian mass extinction |url=https://linkinghub.elsevier.com/retrieve/pii/S0031018214004118 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=414 |pages=225–232 |doi=10.1016/j.palaeo.2014.08.014 |bibcode=2014PPP...414..225N |access-date=18 June 2024 |via=Elsevier Science Direct|url-access=subscription }}</ref> Post-PTME hybodonts exhibited extremely rapid tooth replacement.<ref>{{Cite journal |last1=Wen |first1=Wen |last2=Zhang |first2=Qiyue |last3=Kriwet |first3=Jürgen |last4=Hu |first4=Shixue |last5=Zhou |first5=Changyong |last6=Huang |first6=Jinyuan |last7=Cui |first7=Xindong |last8=Min |first8=Xiao |last9=Benton |first9=Michael James |date=1 May 2023 |title=First occurrence of hybodontid teeth in the Luoping Biota (Middle Triassic, Anisian) and recovery of the marine ecosystem after the end-Permian mass extinction |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=617 |pages=111471 |doi=10.1016/j.palaeo.2023.111471 |doi-access=free |bibcode=2023PPP...61711471W }}</ref> Ichthyopterygians appear to have ballooned in size extremely rapidly following the PTME.<ref>{{Cite journal |last1=Nakajima |first1=Yasuhisa |last2=Shigeta |first2=Yasunari |last3=Houssaye |first3=Alexandra |last4=Zakharov |first4=Yuri D. |last5=Popov |first5=Alexander M. |last6=Sander |first6=P. Martin |date=1 April 2022 |title=Early Triassic ichthyopterygian fossils from the Russian Far East |journal=[[Scientific Reports]] |language=en |volume=12 |issue=1 |pages=5546 |doi=10.1038/s41598-022-09481-6 |pmid=35365703 |issn=2045-2322 |pmc=8976075 |bibcode=2022NatSR..12.5546N }}</ref>

Bivalves rapidly recolonized many marine environments in the wake of the catastrophe.<ref>{{cite journal |last1=Song |first1=Ting |last2=Tong |first2=Jinnan |last3=Tian |first3=Li |last4=Chu |first4=Daoliang |last5=Huang |first5=Yunfei |date=1 April 2019 |title=Taxonomic and ecological variations of Permian-Triassic transitional bivalve communities from the littoral clastic facies in southwestern China |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217311100 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=519 |pages=108–123 |doi=10.1016/j.palaeo.2018.02.027 |bibcode=2019PPP...519..108S |s2cid=134649495 |access-date=2 April 2023|url-access=subscription }}</ref> Bivalves were fairly rare before the P–Tr extinction but became numerous and diverse in the Triassic, taking over niches that were filled primarily by brachiopods before the mass extinction event.<ref name="ChenTongLiaoChen2010">{{cite journal |last1=Chen |first1=Zhong-Qiang |last2=Tong |first2=Jinnan |last3=Liao |first3=Zhuo-Ting |last4=Chen |first4=Jing |date=August 2010 |title=Structural changes of marine communities over the Permian–Triassic transition: Ecologically assessing the end-Permian mass extinction and its aftermath |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818110000871 |journal=[[Global and Planetary Change]] |volume=73 |issue=1–2 |pages=123–140 |doi=10.1016/j.gloplacha.2010.03.011 |bibcode=2010GPC....73..123C |access-date=6 November 2022|url-access=subscription }}</ref> Bivalves were once thought to have outcompeted brachiopods, but this outdated hypothesis about the brachiopod-bivalve transition has been disproven by [[Bayesian analysis]].<ref>{{Cite journal |last1=Guo |first1=Zhen |last2=Flannery-Sutherland |first2=Joseph T. |last3=Benton |first3=Michael J. |last4=Chen |first4=Zhong-Qiang |date=9 September 2023 |title=Bayesian analyses indicate bivalves did not drive the downfall of brachiopods following the Permian-Triassic mass extinction |url=https://www.researchgate.net/publication/373816337 |journal=[[Nature Communications]] |language=en |volume=14 |issue=1 |page=5566 |doi=10.1038/s41467-023-41358-8 |issn=2041-1723 |pmc=10492784 |pmid=37689772 |bibcode=2023NatCo..14.5566G |access-date=24 November 2023}}</ref> The success of bivalves in the aftermath of the extinction event may have been a function of them possessing greater resilience to environmental stress compared to the brachiopods that they coexisted with,<ref name="ClaphamBottjer2007PNAS">{{cite journal |last1=Clapham |first1=Matthew E. |last2=Bottjer |first2=David J. |date=7 August 2007 |title=Prolonged Permian–Triassic ecological crisis recorded by molluscan dominance in Late Permian offshore assemblages |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=104 |issue=32 |pages=12971–12975 |doi=10.1073/pnas.0705280104 |pmid=17664426 |pmc=1941817 |doi-access=free |bibcode=2007PNAS..10412971C }}</ref> whilst other studies have emphasised the greater niche breadth of the former.<ref>{{Cite journal |last1=Afanasjeva |first1=G. A. |last2=Viskova |first2=L. A. |date=20 December 2021 |title=Morphophysiological Peculiarities of Articulated Brachiopods and Marine Bryozoans as a Reason for Their Different Evolutionary Consequences of the Permian–Triassic Crisis |url=https://link.springer.com/10.1134/S0031030121070029 |journal=[[Paleontological Journal]] |language=en |volume=55 |issue=7 |pages=742–751 |doi=10.1134/S0031030121070029 |bibcode=2021PalJ...55..742A |issn=0031-0301 |access-date=18 June 2024 |via=Springer Link|url-access=subscription }}</ref> The rise of bivalves to taxonomic and ecological dominance over brachiopods was not synchronous, however, and brachiopods retained an outsized ecological dominance into the Middle Triassic even as bivalves eclipsed them in taxonomic diversity.<ref name="MesozoicReturnPalaeozoicFauna">{{cite journal |last1=Greene |first1=Sarah E. |last2=Bottjer |first2=David J. |last3=Hagdorn |first3=Hans |last4=Zonneveld |first4=John-Paul |date=15 July 2011 |title=The Mesozoic return of Paleozoic faunal constituents: A decoupling of taxonomic and ecological dominance during the recovery from the end-Permian mass extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018210005134 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=308 |issue=1–2 |pages=224–232 |doi=10.1016/j.palaeo.2010.08.019 |bibcode=2011PPP...308..224G |access-date=2 April 2023|url-access=subscription }}</ref> Some researchers think the brachiopod-bivalve transition was attributable not only to the end-Permian extinction but also the ecological restructuring that began as a result of the Capitanian extinction.<ref>{{cite journal |url=http://gsa.confex.com/gsa/2006AM/finalprogram/abstract_111312.htm |vauthors=Clapham ME, Bottjer DJ, Shen S |year=2006 |title=Decoupled diversity and ecology during the end-Guadalupian extinction (late Permian) |journal=Geological Society of America Abstracts with Programs |volume=38 |issue=7 |access-date=28 March 2008 |page=117 |archive-url=https://web.archive.org/web/20151208110315/https://gsa.confex.com/gsa/2006AM/finalprogram/abstract_111312.htm |archive-date=2015-12-08 |url-status=dead}}</ref> Infaunal habits in bivalves became more common after the PTME.<ref>{{Cite journal |last=McRoberts |first=Christopher A. |date=1 April 2001 |title=Triassic bivalves and the initial marine Mesozoic revolution: A role for predators? |url=https://pubs.geoscienceworld.org/geology/article/29/4/359-362/198478 |journal=[[Geology (journal)|Geology]] |language=en |volume=29 |issue=4 |pages=359 |doi=10.1130/0091-7613(2001)029<0359:TBATIM>2.0.CO;2 |bibcode=2001Geo....29..359M |issn=0091-7613 |access-date=20 September 2023|url-access=subscription }}</ref>

Linguliform brachiopods were commonplace immediately after the extinction event, their abundance having been essentially unaffected by the crisis. Adaptations for oxygen-poor and warm environments, such as increased lophophoral cavity surface, shell width/length ratio, and shell miniaturization, are observed in post-extinction linguliforms.<ref>{{cite journal |last1=Posenato |first1=Renato |last2=Holmer |first2=Lars E. |last3=Prinoth |first3=Herwig |date=1 April 2014 |title=Adaptive strategies and environmental significance of lingulid brachiopods across the late Permian extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018214000479 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=399 |pages=373–384 |doi=10.1016/j.palaeo.2014.01.028 |bibcode=2014PPP...399..373P |access-date=14 January 2023}}</ref> The surviving brachiopod fauna was very low in diversity and exhibited no provincialism whatsoever.<ref>{{cite journal |last1=Ke |first1=Yan |last2=Shen |first2=Shu-zhong |last3=Shi |first3=Guang R. |last4=Fan |first4=Jun-xuan |last5=Zhang |first5=Hua |last6=Qiao |first6=Li |last7=Zeng |first7=Yong |date=15 April 2016 |title=Global brachiopod palaeobiogeographical evolution from Changhsingian (Late Permian) to Rhaetian (Late Triassic) |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018215005593 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=448 |pages=4–25 |doi=10.1016/j.palaeo.2015.09.049 |bibcode=2016PPP...448....4K |access-date=3 July 2023|url-access=subscription }}</ref> Brachiopods began their recovery around 250.1 ± 0.3 Ma, as marked by the appearance of the genus ''Meishanorhynchia'', believed to be the first of the progenitor brachiopods that evolved after the mass extinction.<ref>{{cite journal |last1=Chen |first1=Zhong-Qiang |last2=Shi |first2=Guang R. |last3=Kaiho |first3=Kunio |date=24 November 2003 |title=A New Genus of Rhynchonellid Brachiopod from the Lower Triassic of South China and Implications for Timing the Recovery of Brachiopoda After the End-Permian Mass Extinction |journal=[[Palaeontology (journal)|Palaeontology]] |volume=45 |issue=1 |pages=149–164 |doi=10.1111/1475-4983.00231 |s2cid=128441580 |doi-access=free }}</ref> Major brachiopod rediversification only began in the late Spathian and Anisian in conjunction with the decline of widespread anoxia and extreme heat and the expansion of more habitable climatic zones.<ref>{{cite journal |last1=Shen |first1=Jing |last2=Tong |first2=Jinnan |last3=Song |first3=Haijun |last4=Luo |first4=Mao |last5=Huang |first5=Yunfei |last6=Xiang |first6=Ye |date=1 September 2015 |title=Recovery pattern of brachiopods after the Permian–Triassic crisis in South China |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018215002771 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=433 |pages=91–105 |doi=10.1016/j.palaeo.2015.05.020 |bibcode=2015PPP...433...91C |access-date=26 June 2023|url-access=subscription }}</ref> Brachiopod taxa during the Anisian recovery interval were only phylogenetically related to Late Permian brachiopods at a familial taxonomic level or higher; the ecology of brachiopods had radically changed from before in the mass extinction's aftermath.<ref>{{cite journal |last1=Rong |first1=Jia-yu |last2=Shen |first2=Shu-zhong |date=1 December 2002 |title=Comparative analysis of the end-Permian and end-Ordovician brachiopod mass extinctions and survivals in South China |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018202005072 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=188 |issue=1–2 |pages=25–38 |doi=10.1016/S0031-0182(02)00507-2 |bibcode=2002PPP...188...25R |access-date=18 April 2023|url-access=subscription }}</ref>

Ostracods were extremely rare during the basal-most Early Triassic.<ref>{{cite journal |last1=Forel |first1=Marie-Béatrice |last2=Crasquin |first2=Sylvie |date=6 September 2011 |title=Lower Triassic ostracods (Crustacea) from the Meishan section, Permian–Triassic boundary GSSP (Zhejiang Province, South China) |url=https://www.tandfonline.com/doi/abs/10.1080/14772019.2010.526638?journalCode=tjsp20 |journal=[[Journal of Systematic Palaeontology]] |volume=9 |issue=3 |pages=455–466 |doi=10.1080/14772019.2010.526638 |bibcode=2011JSPal...9..455F |s2cid=128739624 |access-date=23 May 2023|url-access=subscription }}</ref> Taxa associated with microbialites were disproportionately represented among ostracod survivors.<ref name="Forel2012" /> Ostracod recovery began in the Spathian.<ref>{{cite journal |last1=Crasquin |first1=Sylvie |last2=Forel |first2=Marie-Béatrice |date=October 2014 |title=Ostracods (Crustacea) through Permian–Triassic events |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825213000184 |journal=[[Earth-Science Reviews]] |volume=137 |pages=52–64 |doi=10.1016/j.earscirev.2013.01.006 |bibcode=2014ESRv..137...52C |access-date=23 May 2023}}</ref> Despite high taxonomic turnover, the ecological life modes of Early Triassic ostracods remained rather similar to those of pre-PTME ostracods.<ref>{{cite journal |last1=Forel |first1=Marie-Béatrice |last2=Crasquin |first2=Sylvie |last3=Kershaw |first3=S. |last4=Feng |first4=Q. L. |last5=Collin |first5=P.-Y. |date=13 July 2009 |title=Ostracods (Crustacea) and water oxygenation in the earliest Triassic of South China: implications for oceanic events at the end-Permian mass extinction |url=https://www.tandfonline.com/doi/abs/10.1080/08120090903002631 |journal=[[Australian Journal of Earth Sciences]] |volume=56 |issue=6 |pages=815–823 |doi=10.1080/08120090903002631 |bibcode=2009AuJES..56..815F |s2cid=128700856 |access-date=23 May 2023|url-access=subscription }}</ref>

Bryozoans in the Early Triassic were restricted to the Boreal realm.<ref name="PowersAndBottjer2009">{{Cite journal |last1=Powers |first1=Catherine M. |last2=Bottjer |first2=David J. |date=2 November 2009 |title=Behavior of lophophorates during the end-Permian mass extinction and recovery |url=https://www.sciencedirect.com/science/article/pii/S136791200800076X |journal=[[Journal of Asian Earth Sciences]] |language=en |volume=36 |issue=6 |pages=413–419 |doi=10.1016/j.jseaes.2008.05.002 |bibcode=2009JAESc..36..413P |access-date=28 October 2024 |via=Elsevier Science Direct|url-access=subscription }}</ref> They were also not diverse, represented mainly by members of [[Trepostomatida]]. During the Middle Triassic, there was a rise in bryozoan diversity, which peaked in the Carnian.<ref>{{Cite journal |last1=Powers |first1=Catherine M. |last2=Pachut |first2=Joseph F. |date=20 May 2016 |title=Diversity and distribution of Triassic bryozoans in the aftermath of the end-Permian mass extinction |url=https://www.cambridge.org/core/product/identifier/S0022336000054482/type/journal_article |journal=[[Journal of Paleontology]] |language=en |volume=82 |issue=2 |pages=362–371 |doi=10.1666/06-131.1 |s2cid=130929034 |issn=0022-3360 |access-date=30 December 2023|url-access=subscription }}</ref> However, bryozoans took until the Late Cretaceous to recover their full diversity.<ref>{{Cite journal |last1=Afanasjeva |first1=G. A. |last2=Viskova |first2=L. A. |date=20 December 2021 |title=Morphophysiological Peculiarities of Articulated Brachiopods and Marine Bryozoans as a Reason for Their Different Evolutionary Consequences of the Permian–Triassic Crisis |url=https://link.springer.com/article/10.1134/S0031030121070029 |journal=[[Paleontological Journal]] |language=en |volume=55 |issue=7 |pages=742–751 |doi=10.1134/S0031030121070029 |bibcode=2021PalJ...55..742A |issn=0031-0301 |access-date=28 October 2024 |via=Springer Link|url-access=subscription }}</ref>

Crinoids ("sea lilies") suffered a selective extinction, resulting in a decrease in the variety of their forms.<ref name=Foote1999>{{cite journal | author = Foote, M. | year = 1999 | title = Morphological diversity in the evolutionary radiation of Paleozoic and post-Paleozoic crinoids | journal = [[Paleobiology (journal)|Paleobiology]] | volume = 25 | issue = sp1 | pages = 1–116| doi = 10.1666/0094-8373(1999)25[1:MDITER]2.0.CO;2 | jstor = 2666042 | s2cid = 85586709 | issn = 0094-8373}}</ref> Though clade analyses suggest the beginning of their recovery to have taken place in the Induan, the recovery of their diversity as measured by fossil evidence was far less rapid, showing up in the late Ladinian.<ref>{{cite journal |last1=Twitchett |first1=Richard J. |last2=Oji |first2=Tatsuo |date=September–October 2005 |title=Early Triassic recovery of echinoderms |url=https://www.sciencedirect.com/science/article/pii/S1631068305000230 |journal=[[Comptes Rendus Palevol]] |volume=4 |issue=6–7 |pages=531–542 |doi=10.1016/j.crpv.2005.02.006 |bibcode=2005CRPal...4..531T |access-date=2 April 2023}}</ref> Their [[adaptive radiation]] after the extinction event resulted in forms possessing flexible arms becoming widespread; [[motility]], predominantly a response to predation pressure, also became far more prevalent.<ref name=Baumiller2008>{{Cite journal | issue = 1| pages = 221–249| year = 2008| doi = 10.1146/annurev.earth.36.031207.124116| volume = 36| journal = [[Annual Review of Earth and Planetary Sciences]]| last1 = Baumiller| title = Crinoid Ecological Morphology| first1 = T. K.|bibcode = 2008AREPS..36..221B }}</ref> Though their taxonomic diversity remained relatively low, crinoids regained much of their ecological dominance by the Middle Triassic epoch.<ref name="MesozoicReturnPalaeozoicFauna" /> Stem-group echinoids survived the PTME.<ref>{{Cite journal |last1=Thompson |first1=Jeffrey R. |last2=Hu |first2=Shi-xue |last3=Zhang |first3=Qi-Yue |last4=Petsios |first4=Elizabeth |last5=Cotton |first5=Laura J. |last6=Huang |first6=Jin-Yuan |last7=Zhou |first7=Chang-yong |last8=Wen |first8=Wen |last9=Bottjer |first9=David J. |date=21 December 2017 |title=A new stem group echinoid from the Triassic of China leads to a revised macroevolutionary history of echinoids during the end-Permian mass extinction |journal=[[Royal Society Open Science]] |language=en |volume=5 |issue=1 |pages=171548 |doi=10.1098/rsos.171548 |issn=2054-5703 |pmc=5792935 |pmid=29410858 }}</ref> The survival of miocidarid echinoids such as ''Eotiaris'' is likely attributable to their ability to thrive in a wide range of environmental conditions.<ref>{{Cite journal |last1=Thompson |first1=Jeffrey R. |last2=Posenato |first2=Renato |last3=Bottjer |first3=David J. |last4=Petsios |first4=Elizabeth |date=30 August 2019 |title=Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction |journal=[[PeerJ]] |language=en |volume=7 |pages=e7361 |doi=10.7717/peerj.7361 |issn=2167-8359 |pmc=6718154 |pmid=31531267 |doi-access=free }}</ref>

Conodonts saw a rapid recovery during the Induan,<ref>{{Cite journal |last1=Metcalfe |first1=Ian |last2=Isozaki |first2=Yukio |date=2 November 2009 |title=Current perspectives on the Permian–Triassic boundary and end-Permian mass extinction: Preface |url=https://www.sciencedirect.com/science/article/pii/S1367912009001655 |journal=[[Journal of Asian Earth Sciences]] |series=End-Permian Mass Extinction: Events & Processes, Age & Timescale, Causative mechanism(s), & Recovery |volume=36 |issue=6 |pages=407–412 |doi=10.1016/j.jseaes.2009.07.009 |bibcode=2009JAESc..36..407M |issn=1367-9120 |access-date=24 November 2023|url-access=subscription }}</ref> with [[Anchignathodontidae|anchignathodontids]] experiencing a diversity peak in the earliest Induan. [[Gondolellidae|Gondolellids]] diversified at the end of the Griesbachian; this diversity spike was most responsible for the overall conodont diversity peak in the Smithian.<ref>{{Cite journal |last1=Martínez-Pérez |first1=Carlos |last2=Plasencia |first2=Pablo |last3=Cascales-Miñana |first3=Borja |last4=Mazza |first4=Michele |last5=Botella |first5=Héctor |date=3 September 2014 |title=New insights into the diversity dynamics of Triassic conodonts |url=http://www.tandfonline.com/doi/abs/10.1080/08912963.2013.808632 |journal=[[Historical Biology]] |language=en |volume=26 |issue=5 |pages=591–602 |doi=10.1080/08912963.2013.808632 |bibcode=2014HBio...26..591M |hdl=2434/223492 |s2cid=53364944 |issn=0891-2963 |access-date=24 November 2023|hdl-access=free }}</ref> Segminiplanate conodonts again experienced a brief period of domination in the early Spathian, probably related to a transient oxygenation of deep waters.<ref>{{Cite journal |last1=Chen |first1=Yanlong |last2=Jiang |first2=Haishui |last3=Lai |first3=Xulong |last4=Yan |first4=Chunbo |last5=Richoz |first5=Sylvain |last6=Liu |first6=Xiaodan |last7=Wang |first7=Lina |date=1 June 2015 |title=Early Triassic conodonts of Jiarong, Nanpanjiang Basin, southern Guizhou Province, South China |url=https://www.sciencedirect.com/science/article/pii/S1367912015001455 |journal=[[Journal of Asian Earth Sciences]] |volume=105 |pages=104–121 |doi=10.1016/j.jseaes.2015.03.014 |bibcode=2015JAESc.105..104C |issn=1367-9120 |access-date=24 November 2023|url-access=subscription }}</ref> Neospathodid conodonts survived the crisis but underwent proteromorphosis.<ref>{{Cite journal |last1=Kiliç |first1=Ali Murat |last2=Plasencia |first2=Pablo |last3=Ishida |first3=Keisuke |last4=Guex |first4=Jean |last5=Hirsch |first5=Francis |date=1 January 2016 |title=Proteromorphosis of Neospathodus (Conodonta) during the Permian–Triassic crisis and recovery |url=https://www.sciencedirect.com/science/article/pii/S0035159816000052 |journal=Revue de Micropaléontologie |volume=59 |issue=1 |pages=33–39 |doi=10.1016/j.revmic.2016.01.003 |bibcode=2016RvMic..59...33K |issn=0035-1598 |access-date=24 November 2023|url-access=subscription }}</ref>

In the PTME's aftermath, disaster taxa of benthic foraminifera filled many of their vacant niches. The recovery of benthic foraminifera was very slow and frequently interrupted until the Spathian.<ref>{{Cite journal |last1=Altıner |first1=Demir |last2=Payne |first2=Jonathan L. |last3=Lehrmann |first3=Daniel J. |last4=Özkan-Altıner |first4=Sevinç |last5=Kelley |first5=Brian M. |last6=Summers |first6=Mindi M. |last7=Yu |first7=Meiyi |date=December 2021 |title=Triassic Foraminifera from the Great Bank of Guizhou, Nanpanjiang Basin, south China: taxonomic account, biostratigraphy, and implications for recovery from end-Permian mass extinction |url=https://www.cambridge.org/core/product/identifier/S002233602100010X/type/journal_article |journal=[[Journal of Paleontology]] |language=en |volume=95 |issue=S84 |pages=1–53 |doi=10.1017/jpa.2021.10 |bibcode=2021JPal...95S...1A |issn=0022-3360 |access-date=12 May 2024 |via=Cambridge Core|url-access=subscription }}</ref> In the Tethys, foraminiferal communities remained low in diversity into the Middle Triassic, with the exception of a notable Ladinian fauna from the Catalonian Basin.<ref>{{Cite journal |last=Márquez |first=Leopoldo |date=12 December 2005 |title=Foraminiferal fauna recovered after the Late Permian extinctions in Iberia and the westernmost Tethys area |url=https://www.sciencedirect.com/science/article/pii/S0031018205003883 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=229 |issue=1–2 |pages=137–157 |doi=10.1016/j.palaeo.2005.06.035 |bibcode=2005PPP...229..137M |access-date=28 October 2024 |via=Elsevier Science Direct|url-access=subscription }}</ref>

Microbial reefs were common across shallow seas for a short time during the earliest Triassic,<ref>{{cite journal |last1=Brayard |first1=Arnaud |last2=Vennin |first2=Emmanuelle |last3=Olivier |first3=Nicolas |last4=Bylund |first4=Kevin G. |last5=Jenks |first5=Jim |last6=Stephen |first6=Daniel A. |last7=Bucher |first7=Hugo |last8=Hofmann |first8=Richard |last9=Goudemand |first9=Nicolas |last10=Escarguel |first10=Gilles |date=18 September 2011 |title=Transient metazoan reefs in the aftermath of the end-Permian mass extinction |url=https://www.nature.com/articles/ngeo1264 |journal=[[Nature Geoscience]] |volume=4 |issue=1 |pages=693–697 |doi=10.1038/ngeo1264 |bibcode=2011NatGe...4..693B |access-date=8 May 2023|url-access=subscription }}</ref><ref>{{Cite journal |last1=باقرپور |first1=برهان |last2=سلیمانی |first2=معصومه |last3=فقیه |first3=علی |date=February 2024 |title=Morphological diversity of microbialites and the significance of sponge remains in the Permian Triassic transition interval from Hambast Range, Central Iran |url=https://doi.org/10.22055/aag.2024.43965.2378 |journal=Advanced Applied Geology |volume=14 |issue=2 |pages=350–369 |doi=10.22055/aag.2024.43965.2378 |access-date=11 September 2024}}</ref> predominating in low latitudes while being rarer in higher latitudes,<ref>{{Cite journal |last1=Kershaw |first1=S. |last2=Crasquin |first2=S. |last3=Li |first3=Y. |last4=Collin |first4=P.-Y. |last5=Forel |first5=M.-B. |last6=Mu |first6=X. |last7=Baud |first7=A. |last8=Wang |first8=Y. |last9=Xie |first9=S. |last10=Maurer |first10=F. |last11=Guo |first11=L. |date=13 November 2011 |title=Microbialites and global environmental change across the Permian–Triassic boundary: a synthesis |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1472-4669.2011.00302.x |journal=[[Geobiology (journal)|Geobiology]] |language=en |volume=10 |issue=1 |pages=25–47 |doi=10.1111/j.1472-4669.2011.00302.x |pmid=22077322 |issn=1472-4677 |access-date=1 August 2024 |via=Wiley Online Library|url-access=subscription }}</ref> occurring both in anoxic and oxic waters.<ref name="PermianTriassicMicrobialiteYangtzePlatform" /> ''Polybessurus''-like microfossils often dominated these earliest Triassic [[microbialite]]s.<ref>{{Cite journal |last1=Zhang |first1=Xi-Yang |last2=Zheng |first2=Quan-Feng |last3=Li |first3=Yue |last4=Yang |first4=Hong-Qiang |last5=Zhang |first5=Hua |last6=Wang |first6=Wen-Qian |last7=Shen |first7=Shu-Zhong |date=15 August 2020 |title=Polybessurus-like fossils as key contributors to Permian–Triassic boundary microbialites in South China |url=https://www.sciencedirect.com/science/article/pii/S0031018220302157 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=552 |pages=109770 |doi=10.1016/j.palaeo.2020.109770 |bibcode=2020PPP...55209770Z |s2cid=219090219 |issn=0031-0182 |access-date=24 November 2023|url-access=subscription }}</ref> Microbial-metazoan reefs appeared very early in the Early Triassic;<ref>{{cite journal |last1=Friesenbichler |first1=Evelyn |last2=Rychoz |first2=Sylvain |last3=Baud |first3=Aymon |last4=Krystyn |first4=Leopold |last5=Sahakyan |first5=Lilit |last6=Vardanyan |first6=Sargis |last7=Peckmann |first7=Jörn |last8=Reitner |first8=Joachim |last9=Heindel |first9=Katrin |date=15 January 2018 |title=Sponge-microbial build-ups from the lowermost Triassic Chanakhchi section in southern Armenia: Microfacies and stable carbon isotopes |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217308829 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=490 |pages=653–672 |doi=10.1016/j.palaeo.2017.11.056 |bibcode=2018PPP...490..653F |access-date=8 May 2023|url-access=subscription }}</ref> and they dominated many surviving communities across the recovery from the mass extinction.<ref name="MartindaleEtAl2019" /> Microbialite deposits appear to have declined in the early [[Griesbachian]] synchronously with a significant sea level drop that occurred then.<ref name="PermianTriassicMicrobialiteYangtzePlatform">{{cite journal |last1=Wu |first1=Siqi |last2=Chen |first2=Zhong-Qiang |last3=Fang |first3=Yuheng |last4=Pei |first4=Yu |last5=Yang |first5=Hao |last6=Ogg |first6=James |date=15 November 2017 |title=A Permian-Triassic boundary microbialite deposit from the eastern Yangtze Platform (Jiangxi Province, South China): Geobiologic features, ecosystem composition and redox conditions |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217305035 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=486 |pages=58–73 |doi=10.1016/j.palaeo.2017.05.015 |bibcode=2017PPP...486...58W |access-date=8 May 2023|url-access=subscription }}</ref> Metazoan-built reefs reemerged during the Olenekian, mainly being composed of sponge biostrome and bivalve buildups.<ref name="MartindaleEtAl2019" /> Keratinous sponges were particularly noteworthy in their integral importance to Early Triassic microbial-metazoan reef communities,<ref>{{cite journal |last1=Wu |first1=Siqi |last2=Chen |first2=Zhong-Qiang |last3=Su |first3=Chunmei |last4=Fang |first4=Yuheng |last5=Yang |first5=Hao |date=April 2022 |title=Keratose sponge fabrics from the lowermost Triassic microbialites in South China: Geobiologic features and Phanerozoic evolution |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818122000546 |journal=[[Global and Planetary Change]] |volume=211 |page=103787 |doi=10.1016/j.gloplacha.2022.103787 |bibcode=2022GPC...21103787W |s2cid=247491746 |access-date=8 May 2023|url-access=subscription }}</ref><ref>{{cite journal |last1=Baud |first1=Aymon |last2=Richoz |first2=Sylvain |last3=Brandner |first3=Rainier |last4=Krystyn |first4=Leopold |last5=Hindel |first5=Katrin |last6=Mohdat |first6=Tayebeh |last7=Mohtat-Aghai |first7=Parvin |last8=Horacek |first8=Micha |date=28 May 2021 |title=Sponge Takeover from End-Permian Mass Extinction to Early Induan Time: Records in Central Iran Microbial Buildups |journal=[[Frontiers in Earth Science]] |volume=9 |page=355 |doi=10.3389/feart.2021.586210 |bibcode=2021FrEaS...9..355B |doi-access=free }}</ref> and they helped to create stability in heavily damaged ecosystems during early phases of biotic recovery.<ref>{{Cite journal |last1=Wu |first1=Siqi |last2=Reitner |first2=Joachim |last3=Harper |first3=David A. T. |last4=Yu |first4=Jianxin |last5=Chen |first5=Zhong-Qiang |date=27 December 2023 |title=New keratose sponges after the end-Permian extinction provide insights into biotic recoveries |url=https://onlinelibrary.wiley.com/doi/10.1111/gbi.12582 |journal=[[Geobiology (journal)|Geobiology]] |language=en |volume=22 |issue=1 |pages=e12582 |doi=10.1111/gbi.12582 |pmid=38385600 |issn=1472-4677 |access-date=11 September 2024 |via=Wiley Online Library}}</ref> "''Tubiphytes''"-dominated reefs appeared at the end of the Olenekian, representing the earliest platform-margin reefs of the Triassic, though they did not become abundant until the late Anisian, when reefs' species richness increased. The first scleractinian corals appear in the late Anisian as well, although they would not become the dominant reef builders until the end of the Triassic period.<ref name="MartindaleEtAl2019">{{cite journal |last1=Martindale |first1=Rowan C. |last2=Foster |first2=William J. |last3=Velledits |first3=Felicitász |date=1 January 2019 |title=The survival, recovery, and diversification of metazoan reef ecosystems following the end-Permian mass extinction event |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018217302213 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=513 |pages=100–115 |doi=10.1016/j.palaeo.2017.08.014 |bibcode=2019PPP...513..100M |s2cid=135338869 |access-date=2 December 2022|url-access=subscription }}</ref> Bryozoans, after sponges, were the most numerous organisms in Tethyan reefs during the Anisian.<ref>{{Cite journal |last1=Senowbari-Daryan |first1=Baba |last2=Zühlke |first2=Rainer |last3=Bechstädt |first3=Thilo |last4=Flügel |first4=Erik |date=December 1993 |title=Anisian (middle triassic) buildups of the Northern Dolomites (Italy): The recovery of reef communities after the permian/triassic crisis |url=http://link.springer.com/10.1007/BF02539736 |journal=Facies |language=en |volume=28 |issue=1 |pages=181–256 |doi=10.1007/BF02539736 |bibcode=1993Faci...28..181S |s2cid=129651368 |issn=0172-9179 |access-date=20 September 2023|url-access=subscription }}</ref> Metazoan reefs became common again during the Anisian because the oceans cooled down then from their overheated state during the Early Triassic.<ref>{{cite journal |last1=Chen |first1=Zhong-Qiang |last2=Tu |first2=Chenyi |last3=Pei |first3=Yu |last4=Ogg |first4=James |last5=Fang |first5=Yuheng |last6=Wu |first6=Siqi |last7=Feng |first7=Xueqian |last8=Huang |first8=Yuangeng |last9=Guo |first9=Zhen |last10=Yang |first10=Hao |date=February 2019 |title=Biosedimentological features of major microbe-metazoan transitions (MMTs) from Precambrian to Cenozoic |url=https://www.sciencedirect.com/science/article/abs/pii/S0012825218303544 |journal=[[Earth-Science Reviews]] |volume=189 |pages=21–50 |doi=10.1016/j.earscirev.2019.01.015 |bibcode=2019ESRv..189...21C |s2cid=134828705 |access-date=20 February 2023|url-access=subscription }}</ref> Biodiversity amongst metazoan reefs did not recover until well into the Anisian, millions of years after non-reef ecosystems recovered their diversity.<ref>{{Cite journal |last1=Kelley |first1=Brian M. |last2=Yu |first2=Meiyi |last3=Lehrmann |first3=Daniel J. |last4=Altıner |first4=Demir |last5=Payne |first5=Jonathan L. |date=14 August 2023 |title=Prolonged and gradual recovery of metazoan-algal reefs following the end-Permian mass extinction |url=https://pubs.geoscienceworld.org/geology/article/doi/10.1130/G51058.1/627616/Prolonged-and-gradual-recovery-of-metazoan-algal |journal=[[Geology (journal)|Geology]] |language=en |volume=51 |issue=11 |pages=1011–1016 |doi=10.1130/G51058.1 |issn=0091-7613 |access-date=12 May 2024 |via=GeoScienceWorld}}</ref> [[Microbially induced sedimentary structure]]s (MISS) from the earliest Triassic have been found to be associated with abundant opportunistic bivalves and vertical burrows, and it is likely that post-extinction microbial mats played a vital, indispensable role in the survival and recovery of various bioturbating organisms.<ref>{{cite journal |last1=Xu |first1=Yanling |last2=Chen |first2=Zhong-Qiang |last3=Feng |first3=Xueqian |last4=Wu |first4=Siqi |last5=Shi |first5=Guang R. |last6=Tu |first6=Chenyi |date=15 May 2017 |title=Proliferation of MISS-related microbial mats following the end-Permian mass extinction in the northern Paleo-Tethys: Evidence from southern Qilianshan region, western China |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018216301274 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=474 |pages=198–213 |doi=10.1016/j.palaeo.2016.04.045 |bibcode=2017PPP...474..198X |access-date=8 May 2023|url-access=subscription }}</ref> The microbialite refuge hypothesis has been criticised as reflecting a taphonomic bias due to the greater preservation potential of microbialite deposits, however, rather than a genuine phenomenon.<ref>{{Cite journal |last1=Foster |first1=William J. |last2=Lehrmann |first2=Daniel J. |last3=Yu |first3=Meiyi |last4=Martindale |first4=Rowan Clare |date=23 May 2019 |title=Facies selectivity of benthic invertebrates in a Permian/Triassic boundary microbialite succession: Implications for the "microbialite refuge" hypothesis |url=https://onlinelibrary.wiley.com/doi/10.1111/gbi.12343 |journal=Geobiology |language=en |volume=17 |issue=5 |pages=523–535 |doi=10.1111/gbi.12343 |pmid=31120196 |bibcode=2019Gbio...17..523F |issn=1472-4677 |access-date=18 June 2024 |via=Wiley Online Library|url-access=subscription }}</ref>

Ichnoconoses show that marine ecosystems recovered to pre-extinction levels of ecological complexity by the late Olenekian.<ref>{{cite journal |last1=Zhao |first1=Xiaoming |last2=Tong |first2=Jinnan |last3=Yao |first3=Huazhou |last4=Niu |first4=Zhijun |last5=Luo |first5=Mao |last6=Huang |first6=Yunfei |last7=Song |first7=Haijun |date=1 July 2015 |title=Early Triassic trace fossils from the Three Gorges area of South China: Implications for the recovery of benthic ecosystems following the Permian–Triassic extinction |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018215001935 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=429 |pages=100–116 |doi=10.1016/j.palaeo.2015.04.008 |bibcode=2015PPP...429..100Z |access-date=20 January 2023|url-access=subscription }}</ref> Anisian ichnoconoses show slightly lower diversity than Spathian ichnoconoses, although this was likely a taphonomic consequence of increased and deeper bioturbation erasing evidence of shallower bioturbation.<ref>{{cite journal |last1=Feng |first1=Xueqian |last2=Chen |first2=Zhong-Qiang |last3=Woods |first3=Adam |last4=Pei |first4=Yu |last5=Wu |first5=Siqi |last6=Fang |first6=Yuheng |last7=Luo |first7=Mao |last8=Xu |first8=Yaling |date=October 2017 |title=Anisian (Middle Triassic) marine ichnocoenoses from the eastern and western margins of the Kamdian Continent, Yunnan Province, SW China: Implications for the Triassic biotic recovery |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818117302278 |journal=[[Global and Planetary Change]] |volume=157 |pages=194–213 |doi=10.1016/j.gloplacha.2017.09.004 |bibcode=2017GPC...157..194F |access-date=20 January 2023|url-access=subscription }}</ref>

[[Ichnological]] evidence suggests that recovery and recolonization of marine environments may have taken place by way of outward dispersal from refugia that suffered relatively mild perturbations and whose local biota were less strongly affected by the mass extinction compared to the rest of the world's oceans.<ref>{{cite journal |last1=Zonneveld |first1=John-Paul |last2=Gingras |first2=Murray |last3=Beatty |first3=Tyler W. |title=Diverse Ichnofossil Assemblages Following the P-T Mass Extinction, Lower Triassic, Alberta and British Columbia, Canada: Evidence for Shallow Marine Refugia on the Northwestern Coast of Pangaea |date=1 January 2010 |url=https://pubs.geoscienceworld.org/sepm/palaios/article-abstract/25/6/368/146150/DIVERSE-ICHNOFOSSIL-ASSEMBLAGES-FOLLOWING-THE-P-T |journal=[[PALAIOS]] |volume=25 |issue=6 |pages=368–392 |doi=10.2110/palo.2009.p09-135r |bibcode=2010Palai..25..368Z |s2cid=128837115 |access-date=20 January 2023|url-access=subscription }}</ref><ref>{{cite journal |last1=Knaust |first1=Dirk |date=11 May 2010 |title=The end-Permian mass extinction and its aftermath on an equatorial carbonate platform: insights from ichnology |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-3121.2010.00934.x |journal=[[Terra Nova (journal)|Terra Nova]] |volume=22 |issue=3 |pages=195–202 |doi=10.1111/j.1365-3121.2010.00934.x |bibcode=2010TeNov..22..195K |s2cid=128722898 |access-date=20 January 2023|url-access=subscription }}</ref> Although complex bioturbation patterns were rare in the Early Triassic, likely reflecting the inhospitability of many shallow water environments in the extinction's wake, complex ecosystem engineering managed to persist locally in some places, and may have spread from there after harsh conditions across the global ocean were ameliorated over time.<ref>{{cite journal |last1=Cribb |first1=Alison T. |last2=Bottjer |first2=David J. |date=14 January 2020 |title=Complex marine bioturbation ecosystem engineering behaviors persisted in the wake of the endPermian mass extinction |url=https://www.researchgate.net/publication/338575606 |journal=[[Scientific Reports]] |volume=10 |issue=1 |page=203 |doi=10.1038/s41598-019-56740-0 |pmid=31937801 |pmc=6959249 |bibcode=2020NatSR..10..203C |s2cid=210169203 |access-date=8 April 2023}}</ref> Wave-dominated shoreface settings (WDSS) are believed to have served as refugium environments because they appear to have been unusually diverse in the mass extinction's aftermath.<ref>{{cite journal |last1=Feng |first1=Xueqian |last2=Chen |first2=Zhong-Qiang |last3=Zhao |first3=Laishi |last4=Lan |first4=Zhongwu |date=February 2021 |title=Middle Permian trace fossil assemblages from the Carnarvon Basin of Western Australia: Implications for the evolution of ichnofaunas in wave-dominated siliciclastic shoreface settings across the Permian-Triassic boundary |url=https://www.sciencedirect.com/science/article/abs/pii/S0921818120302836 |journal=[[Global and Planetary Change]] |volume=197 |page=103392 |doi=10.1016/j.gloplacha.2020.103392 |bibcode=2021GPC...19703392F |s2cid=229416157 |access-date=20 January 2023|url-access=subscription }}</ref>