Editing Mesozoic (section)

==Climate==
The Triassic was generally dry, a trend that began in the late [[Carboniferous]], and highly seasonal, especially in the interior of Pangaea. Low sea levels may have also exacerbated temperature extremes. With its high [[specific heat capacity]], water acts as a temperature-stabilizing heat reservoir, and land areas near large bodies of water—especially oceans—experience less variation in temperature. Because much of Pangaea's land was distant from its shores, temperatures fluctuated greatly, and the interior probably included expansive [[desert]]s. Abundant [[red beds]] and evaporites such as [[halite]] support these conclusions, but some evidence suggests the generally dry climate of the Triassic was punctuated by episodes of increased rainfall.<ref name=Pretoetal2010>{{cite journal |last1=Preto |first1=Nereo |last2=Kustatscher |first2=Evelyn |last3=Wignall |first3=Paul B. |date=15 April 2010 |title=Triassic climates – State of the art and perspectives | journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume = 290 |issue=1–4 |pages=1–10 |doi=10.1016/j.palaeo.2010.03.015 |bibcode=2010PPP...290....1P |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018210001434 |access-date=21 July 2023}}</ref> The most important humid episodes were the [[Carnian Pluvial Event]] and one in the [[Rhaetian]], a few million years before the Triassic–Jurassic extinction event.

Sea levels began to rise during the Jurassic, probably caused by an increase in [[seafloor spreading]]. The formation of new crust beneath the surface displaced ocean waters by as much as {{convert|200|m|0|abbr=on}} above today's sea level, flooding coastal areas. Furthermore, Pangaea began to rift into smaller divisions, creating new shoreline around the Tethys Ocean. Temperatures continued to increase, then began to stabilize. [[Humidity]] also increased with the proximity of water, and deserts retreated.<ref>{{Cite journal |last=Gurung |first=Khushboo |last2=Field |first2=Katie J. |last3=Batterman |first3=Sarah A. |last4=Poulton |first4=Simon W. |last5=Mills |first5=Benjamin J. W. |date=28 February 2024 |title=Geographic range of plants drives long-term climate change |url=https://www.nature.com/articles/s41467-024-46105-1 |journal=[[Nature Communications]] |language=en |volume=15 |issue=1 |doi=10.1038/s41467-024-46105-1 |issn=2041-1723 |pmc=10901853 |pmid=38418475 |access-date=28 June 2024}}</ref>

The climate of the Cretaceous is less certain and more widely disputed. Probably, higher levels of [[carbon dioxide]] in the [[Earth's atmosphere|atmosphere]] are thought to have almost eliminated the north–south [[temperature gradient]]: temperatures were about the same across the planet, and about 10°[[Celsius|C]] higher than today.  The circulation of [[oxygen]] to the deep ocean may also have been disrupted, preventing the [[decomposition]] of large volumes of organic matter, which was eventually [[deposition (sediment)|deposited]] as "[[black shale]]".<ref>{{cite journal |last1=Leckie |first1=R. Mark |last2=Bralower |first2=Timothy J. |last3=Cashman |first3=Richard |title=Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the mid-Cretaceous: OCEANIC ANOXIC EVENTS AND PLANKTON EVOLUTION |journal=[[Paleoceanography and Paleoclimatology]] |date=September 2002 |volume=17 |issue=3 |pages=13–1–13–29 |doi=10.1029/2001PA000623 |doi-access=free}}</ref><ref>{{cite journal |last1=Turgeon |first1=Steven C. |last2=Creaser |first2=Robert A. |title=Cretaceous oceanic anoxic event 2 triggered by a massive magmatic episode |url=https://www.researchgate.net/publication/51407958_Cretaceous_Anoxic_Event_2_triggered_by_a_massive_magmatic_episode |journal=[[Nature (journal)|Nature]] |date=17 July 2008 |volume=454 |issue=7202 |pages=323–326 |doi=10.1038/nature07076 |pmid=18633415 |bibcode=2008Natur.454..323T |s2cid=4315155 |access-date=28 June 2024}}</ref>

Different studies have come to different conclusions about the amount of oxygen in the atmosphere during different parts of the Mesozoic, with some concluding oxygen levels were lower than the current level (about 21%) throughout the Mesozoic,<ref>[[Robert Berner]], John M. VandenBrooks and Peter D. Ward, 2007, [https://www.science.org/doi/abs/10.1126/science.1140273 ''Oxygen and Evolution'']. ''Science 27 April 2007'', Vol. 316 no. 5824 pp. 557–58 . A graph showing the reconstruction from this paper can be found [http://www.oocities.org/marie.mitchell@rogers.com/climate_files/Phanerozoic_Oxygen.gif here], from the webpage [http://www.oocities.org/marie.mitchell@rogers.com/PaleoClimate.html Paleoclimate – The History of Climate Change].</ref><ref>[[Robert Berner|Berner R. A.]] 2006 ''GEOCARBSULF: a combined model for Phanerozoic atmospheric O2 and CO2''. Geochim. Cosmochim. Acta 70, 5653–64. See the dotted line in Fig. 1 of [http://rspb.royalsocietypublishing.org/content/early/2010/03/04/rspb.2010.0001.full ''Atmospheric oxygen level and the evolution of insect body size''] by Jon F. Harrison, Alexander Kaiser and John M. VandenBrooks</ref> some concluding they were lower in the Triassic and part of the Jurassic but higher in the Cretaceous,<ref>[[Robert Berner|Berner]], Robert A., 2009, [http://www.ajsonline.org/content/309/7/603.abstract ''Phanerozoic atmospheric oxygen: New results using the GEOCARBSULF model'']. ''Am. J. Sci.'' 309 no. 7, 603–06. A graph showing the reconstructed levels in this paper can be found on [https://books.google.com/books?id=GdRnFn7I38kC&pg=PA31 p. 31] of the book ''Living Dinosaurs'' by [[Gareth J. Dyke|Gareth Dyke]] and Gary Kaiser.</ref><ref>[[Robert Berner|Berner R. A.]], Canfield D. E. 1989 ''A new model for atmospheric oxygen over phanerozoic time''. ''Am. J. Sci.'' 289, 333–61. See the solid line in Fig. 1 of [http://rspb.royalsocietypublishing.org/content/early/2010/03/04/rspb.2010.0001.full ''Atmospheric oxygen level and the evolution of insect body size''] by Jon F. Harrison, Alexander Kaiser and John M. VandenBrooks</ref><ref>[[Robert Berner|Berner, R]], et al., 2003, ''Phanerozoic atmospheric oxygen'', Annu. Rev. Earth Planet. Sci., V, 31, p. 105–34. See the graph near the bottom of the webpage [http://essayweb.net/geology/timeline/phanerozoic.shtml Phanerozoic Eon] {{webarchive|url=https://web.archive.org/web/20130427055918/http://essayweb.net/geology/timeline/phanerozoic.shtml |date=27 April 2013 }}</ref> and some concluding they were higher throughout most or all of the Triassic, Jurassic and Cretaceous.<ref>Glasspool, I.J., Scott, A.C., 2010, ''Phanerozoic concentrations of atmospheric oxygen reconstructed from sedimentary charcoal'', [[Nature Geoscience]], 3, 627–30</ref><ref>Bergman N. M., Lenton T. M., Watson A. J. 2004 COPSE: a new model of biogeochemical cycling over Phanaerozoic time. ''Am. J. Sci.'' 304, 397–437. See the dashed line in Fig. 1 of [http://rspb.royalsocietypublishing.org/content/early/2010/03/04/rspb.2010.0001.full ''Atmospheric oxygen level and the evolution of insect body size''] by Jon F. Harrison, Alexander Kaiser and John M. VandenBrooks</ref>