View source for Triassic

{{Short description|First period of the Mesozoic Era}}
{{Infobox geologic timespan
| name                         = {{Color|white|Triassic}}
| color                        = Triassic
| top_bar                      =
| time_start                   = 251.902
| time_start_uncertainty       = 0.024
| time_end                     = 201.4
| time_end_uncertainty         = 0.2
| image_map                    = Mollweide Paleographic Map of Earth, 225 Ma (Norian Age).png 
| caption_map                  = A map of Earth as it appeared during the [[Norian]] age of the [[Late Triassic]]
| image_outcrop                =
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<!--Chronology-->  
| timeline                     = Triassic
<!--Etymology-->
| name_formality               = Formal
| name_accept_date             =
| alternate_spellings          =
| synonym1                     =
| synonym1_coined              =
| synonym2                     =
| synonym2_coined              =
| synonym3                     =
| synonym3_coined              =
| nicknames                    =
| former_names                 =
| proposed_names               =
<!--Usage Information--> 
| celestial_body               = earth
| usage                        = Global ([[International Commission on Stratigraphy|ICS]])
| timescales_used              = ICS Time Scale
| formerly_used_by             =
| not_used_by                  =
<!--Definition-->
| chrono_unit                  = Period
| strat_unit                   = System
| proposed_by                  =
| timespan_formality           = Formal
| lower_boundary_def           = First appearance of the [[conodont]] ''[[Hindeodus|Hindeodus parvus]]''
| lower_gssp_location          = [[Meishan]], [[Zhejiang]], [[China]]
| lower_gssp_coords            = {{Coord|31.0798|N|119.7058|E|display=inline}}
| lower_gssp_accept_date  = 2001<ref>{{cite journal |last1=Hongfu |first1=Yin |last2=Kexin |first2=Zhang |last3=Jinnan |first3=Tong |last4=Zunyi |first4=Yang |last5=Shunbao |first5=Wu |title=The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary |journal=Episodes |date=June 2001 |volume=24 |issue=2 |pages=102–114 |doi=10.18814/epiiugs/2001/v24i2/004 |url=https://stratigraphy.org/gssps/files/induan.pdf |access-date=8 December 2020 |doi-access=free}}</ref>
| upper_boundary_def   = First appearance of the [[ammonite]] ''[[Psiloceras|Psiloceras spelae tirolicum]]''
| upper_gssp_location   = Kuhjoch section, [[Karwendel|Karwendel mountains]], [[Northern Calcareous Alps]], Austria
| upper_gssp_coords   = {{Coord|47.4839|N|11.5306|E|display=inline}}
| upper_gssp_accept_date  = 2010<ref>{{cite journal |last1=Hillebrandt |first1=A.v. |last2=Krystyn |first2=L. |last3=Kürschner |first3=W. M. |last4=Bonis |first4=N. R. |last5=Ruhl |first5=M. |last6=Richoz |first6=S. |last7=Schobben |first7=M. A. N. |last8=Urlichs |first8=M. |last9=Bown |first9=P.R. |last10=Kment |first10=K. |last11=McRoberts |first11=C. A. |last12=Simms |first12=M. |last13=Tomãsových |first13=A. |display-authors=3 |title=The Global Stratotype Sections and Point (GSSP) for the base of the Jurassic System at Kuhjoch (Karwendel Mountains, Northern Calcareous Alps, Tyrol, Austria) |journal=Episodes |date=September 2013 |volume=36 |issue=3 |pages=162–198 |doi=10.18814/epiiugs/2013/v36i3/001 |doi-access=free |citeseerx=10.1.1.736.9905|s2cid=128552062 }}</ref>
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}}

The '''Triassic''' ({{IPAc-en|t|r|aɪ|ˈ|æ|s|ɪ|k}}; sometimes symbolized as '''🝈''') is a [[geologic period]] and a [[system (stratigraphy)|stratigraphic system]] that spans 50.5 million years from the end of the [[Permian]] Period 251.902 Ma (million years ago) to the beginning of the [[Jurassic]] Period 201.4 Ma.<ref name="StratChart 2023">{{cite web |title=International Stratigraphic Chart |url=https://stratigraphy.org/ICSchart/ChronostratChart2023-06.pdf |publisher=International Commission on Stratigraphy | date=June 2023 |access-date=19 July 2023}}</ref><ref>{{dictionary.com|Triassic}}</ref> The Triassic Period is the first and shortest geologic period of the [[Mesozoic|Mesozoic Era]], and the seventh period of the [[Phanerozoic|Phanerozoic Eon]]. The start and the end of the Triassic Period featured major [[extinction event]]s.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{cite journal |url=|author1=Sahney, S. |author2=Benton, M.J. |name-list-style=amp |year=2008 |title=Recovery from the most profound mass extinction of all time |journal=Proceedings of the Royal Society B: Biological Sciences |doi=10.1098/rspb.2007.1370 |volume=275 |pmid=18198148 |issue=1636 |pmc=2596898 |pages=759–765}}</ref>

Chronologically, the Triassic Period is divided into three epochs: (i) the [[Early Triassic]], (ii) the [[Middle Triassic]], and (iii) the [[Late Triassic]]. The Triassic Period began after the [[Permian–Triassic extinction event]] that much reduced the [[biosphere]] of planet Earth. The fossil record of the Triassic Period presents three categories of organisms: (i) animals that survived the Permian–Triassic extinction event, (ii) new animals that briefly flourished in the Triassic biosphere, and (iii) new animals that evolved and dominated the [[Mesozoic]] Era. [[Reptiles]], especially [[archosaur]]s, were the chief terrestrial vertebrates during this time. A specialized group of archosaurs, called [[dinosaur]]s, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period.<ref name="Brusatte">{{cite journal |last1=Brusatte |first1=S. L. |last2=Benton |first2=M. J. |last3=Ruta |first3=M. |last4=Lloyd |first4=G. T. |title=Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs |journal=[[Science (journal)|Science]] |volume=321 |issue=5895 |pages=1485–1488 |date=2008-09-12 |url=http://palaeo.gly.bris.ac.uk/Benton/reprints/2008Science.pdf |doi=10.1126/science.1161833 |access-date=2012-01-14 |bibcode=2008Sci...321.1485B |pmid=18787166 |s2cid=13393888 |archive-url=https://web.archive.org/web/20140624204033/http://palaeo.gly.bris.ac.uk/Benton/reprints/2008Science.pdf |archive-date=2014-06-24 |hdl=20.500.11820/00556baf-6575-44d9-af39-bdd0b072ad2b |hdl-access=free}}</ref> Archosaurs that became dominant in this period were primarily [[pseudosuchia]]ns, relatives and ancestors of modern [[crocodilians]], while some archosaurs specialized in flight, the first time among vertebrates, becoming the [[pterosaurs]]. [[Therapsids]], the dominant vertebrates of the preceding Permian period, saw a brief surge in diversification in the Triassic, with [[Dicynodontia|dicynodonts]] and [[Cynodontia|cynodonts]] quickly becoming dominant, but they declined throughout the period with the majority becoming extinct by the end. However, the first stem-group [[mammal]]s ([[Mammaliamorpha|mammaliamorphs]]), themselves a specialized subgroup of cynodonts, appeared during the Triassic and would survive the extinction event, allowing them to radiate during the Jurassic. [[Amphibian|Amphibians]] were primarily represented by the [[Temnospondyli|temnospondyls]], giant aquatic predators that had survived the end-Permian extinction and saw a new burst of diversification in the Triassic, before going extinct by the end; however, early crown-group [[Lissamphibia|lissamphibians]] (including stem-group [[Frog|frogs]], [[Salamander|salamanders]] and [[Caecilian|caecilians]]) also became more common during the Triassic and survived the extinction event. The earliest known [[Neopterygii|neopterygian]] fish, including early [[Holostei|holosteans]] and [[Teleost|teleosts]], appeared near the beginning of the Triassic, and quickly diversified to become among the dominant groups of fish in both freshwater and marine habitats.

The vast [[supercontinent]] of [[Pangaea]] dominated the globe during the Triassic, but in the latest Triassic ([[Rhaetian]]) and Early Jurassic it began to gradually rift into two separate landmasses: [[Laurasia]] to the north and [[Gondwana]] to the south. The global climate during the Triassic was mostly hot and dry,<ref>{{cite web |url=http://news.nationalgeographic.com/news/2012/10/121018-triassic-extinctions-hot-global-warming-science-environment/ |archive-url=https://web.archive.org/web/20121020072805/http://news.nationalgeographic.com/news/2012/10/121018-triassic-extinctions-hot-global-warming-science-environment/ |archive-date=October 20, 2012 |title='Lethally Hot' Earth Was Devoid of Life – Could It Happen Again? |date=19 October 2012 |work=National Geographic}}</ref> with deserts spanning much of Pangaea's interior. However, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another major mass extinction, the [[Triassic–Jurassic extinction event]], that wiped out many groups, including most pseudosuchians, and allowed dinosaurs to assume dominance in the Jurassic.

==Etymology==
The Triassic was named in 1834 by [[Friedrich August von Alberti]], after a succession of three distinct rock layers (Greek {{wikt-lang|grc-Latn|τριάς|triás}} meaning 'triad') that are widespread in southern [[Germany]]: the lower [[Buntsandstein]] (colourful [[sandstone]]'')'', the middle [[Muschelkalk]] (shell-bearing [[limestone]]) and the upper [[Keuper]] (coloured [[clay]]).<ref>Friedrich von Alberti, ''Beitrag zu einer Monographie des bunten Sandsteins, Muschelkalks und Keupers, und die Verbindung dieser Gebilde zu einer Formation'' [Contribution to a monograph on the colored sandstone, shell limestone and mudstone, and the joining of these structures into one formation] (Stuttgart and Tübingen, (Germany):  J. G. Cotta, 1834).  Alberti coined the term "Trias" on  [https://archive.org/details/bub_gb_Ie27AAAAIAAJ/page/n347 <!-- pg=324 --> page 324] :<br />"… bunter Sandstein, Muschelkalk und Keuper das Resultat einer Periode, ihre Versteinerungen, um mich der Worte E. de Beaumont's zu bedeinen, die Thermometer einer geologischen Epoche seyen, … also die bis jezt beobachtete Trennung dieser Gebilde in 3 Formationen nicht angemessen, und es mehr dem Begriffe Formation entsprechend sey, sie zu einer Formation, welche ich vorläufig ''Trias'' nennen will, zu verbinden."<br />( … colored sandstone, shell limestone, and mudstone are the result of a period; their fossils are, to avail myself of the words of E. de Beaumont, the thermometer of a geologic epoch; … thus the separation of these structures into 3 formations, which has been maintained until now, isn't appropriate, and it is more consistent with the concept of "formation" to join them into one formation, which for now I will name "trias".)</ref>

<gallery class="center" widths="190px">
File:Stadtroda Sandstein.jpg|[[Early Triassic]] sandstone (Buntsandstein) near [[Stadtroda]], Germany
File:Obere Schaumkalkbank am Altenberg bei Dörzbach 280308.jpg|[[Middle Triassic]] Muschelkalk (shell-bearing limestone) near [[Dörzbach]], Germany
File:Kirnbergaufschluss.JPG|[[Late Triassic]] [[Steigerwald Formation]] and overlying [[Hassberge Formation]] in [[Schönbuch]], Germany
</gallery>

==Dating and subdivisions==
On the [[geologic time scale]], the Triassic is usually divided into [[Early Triassic|Early]], [[Middle Triassic|Middle]], and [[Late Triassic]] [[epoch (geology)|Epoch]]s, and the corresponding rocks are referred to as Lower, Middle, or Upper Triassic. The [[faunal stages]] from the youngest to oldest are:

{|
! span=col| Series/Epoch
! span=col| Faunal stage
! span=col| Time span
|-
| rowspan="3", style="background-color: {{period color|Late Triassic}};" | {{Colored period link|Late Triassic|'''Upper/Late Triassic''' (Tr3)}}
|style="background-color: {{period color|Rhaetian}};" | {{Colored period link|Rhaetian}}
|({{period start|Rhaetian}} {{period start error|Rhaetian}} – {{period end|Rhaetian}} {{period end error|Rhaetian}} Ma)
|-
|style="background-color: {{period color|Norian}};" | {{Colored period link|Norian}}
|({{period start|Norian}} {{period start error|Norian}} – {{period end|Norian}} {{period end error|Norian}} Ma)
|-
|style="background-color: {{period color|Carnian}};" | {{Colored period link|Carnian}}
|({{period start|Carnian}} {{period start error|Carnian}} – {{period end|Carnian}} {{period end error|Carnian}} Ma)
|-
| rowspan="2", style="background-color: {{period color|Middle Triassic}}" | {{Colored period link|Middle Triassic|'''Middle Triassic''' (Tr2)}}
|style="background-color: {{period color|Ladinian}};" | {{Colored period link|Ladinian}}
|({{period start|Ladinian}} {{period start error|Ladinian}} – {{period end|Ladinian}} {{period end error|Ladinian}} Ma)
|-
|style="background-color: {{period color|Anisian}};" | {{Colored period link|Anisian}}
|({{period start|Anisian}} {{period start error|Anisian}} – {{period end|Anisian}} {{period end error|Anisian}} Ma)
|-
| rowspan="2", style="background-color: {{period color|Early Triassic}};" | {{Colored period link|Early Triassic|'''Lower/Early Triassic''' (Scythian)}}
|style="background-color: {{period color|Olenekian}};" | {{Colored period link|Olenekian}}
|({{period start|Olenekian}} {{period start error|Olenekian}} – {{period end|Olenekian}} {{period end error|Olenekian}} Ma)
|-
|style="background-color: {{period color|Induan}};" | {{Colored period link|Induan}}
|({{period start|Induan}} {{period start error|Induan}} – {{period end|Induan}} {{period end error|Induan}} Ma)
|}

==Paleogeography==
[[File:230 Ma plate tectonic reconstruction.png|thumb|upright=1.5|350px|View of the Tethys area during the Ladinian stage (230&nbsp;Ma)]]
[[File:Pangaea (230 million years ago).png|thumb|350px|230&nbsp;Ma continental reconstruction]]At the beginning of the Triassic, all the major continents were amalgamated into the supercontinent of Pangea. Centred on the equator, this stretched in an arc from the north to south polar regions with [[Laurasia|Laurussia]] in the north and Gondwana in the south. The [[Tethys Ocean|Paleo]]- and [[Tethys Ocean|Neo-Tethys]] oceans lay within the arc of the supercontinent with the vast [[Panthalassa]] Ocean beyond.<ref name=":1">{{Cite book |last1=Torsvik |first1=Trond H. |title=Earth history and palaeogeography |last2=Cocks |first2=Leonard Robert Morrison |date=2017 |publisher=Cambridge university press |isbn=978-1-107-10532-4 |location=Cambridge}}</ref> [[North China Craton|North China]] and [[Amur plate|Amuria]], and [[South China Craton|South China]] were separated from Pangea by the Paleoasian Ocean, but this closed by the Late Triassic.<ref name=":3">{{Cite journal |last1=Song |first1=Dongfang |last2=Xiao |first2=Wenjiao |last3=Ao |first3=Songjian |last4=Mao |first4=Qigui |last5=Wan |first5=Bo |last6=Zeng |first6=Hao |date=2024-06-01 |title=Contemporaneous closure of the Paleo-Asian Ocean in the Middle-Late Triassic: A synthesis of new evidence and tectonic implications for the final assembly of Pangea |url=https://www.sciencedirect.com/science/article/pii/S0012825224000989 |journal=Earth-Science Reviews |volume=253 |article-number=104771 |doi=10.1016/j.earscirev.2024.104771 |bibcode=2024ESRv..25304771S |issn=0012-8252|url-access=subscription }}</ref>

Pangea was surrounded by [[Subduction|subduction zones]] that dipped beneath the supercontinent. The great mountain ranges that marked the Late Paleozoic continental collisions were largely eroded and were being replaced by regions of thinned crust that lay along the lines of the future [[Atlantic Ocean|Atlantic]], [[Indian Ocean|Indian]] and [[Southern Ocean|Southern]] oceans.<ref name=":1" /><ref name=":4">{{Cite book |last1=Scotese |first1=C. R. |chapter=3: Late Permian-Early Jurassic Paleogeography of Western Tethys and the World |date=2017-01-01 |title=Permo-Triassic Salt Provinces of Europe, North Africa and the Atlantic Margins |pages=57–95 |editor-last=Soto |editor-first=Juan I. |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128094174000045 |access-date=2025-06-25 |publisher=Elsevier |isbn=978-0-12-809417-4 |last2=Schettino |first2=A. |editor2-last=Flinch |editor2-first=Joan F. |editor3-last=Tari |editor3-first=Gabor}}</ref>

The supercontinent changed motion from drifting westward to rotating counterclockwise during late Permian. This continued until the Carnian (c. 230 Ma), after which it resumed the westward motion. These changes in motion were triggered by the opening of the Neo-Tethys, and closing of the Paleo-Tethys respectively, and affected tectonic regimes particularly along the southern and western margins.<ref name=":5">{{Cite journal |last1=Riel |first1=Nicolas |last2=Jaillard |first2=Etienne |last3=Martelat |first3=Jean-Emmanuel |last4=Guillot |first4=Stéphane |last5=Braun |first5=Jean |date=2018-01-01 |title=Permian-Triassic Tethyan realm reorganization: Implications for the outward Pangea margin |url=https://www.sciencedirect.com/science/article/pii/S0895981117302535 |journal=Journal of South American Earth Sciences |volume=81 |pages=78–86 |doi=10.1016/j.jsames.2017.11.007 |bibcode=2018JSAES..81...78R |issn=0895-9811|url-access=subscription }}</ref>

The narrow [[Cimmeria (continent)|Cimmerian]] [[Terrane|terranes]] that had rifted from the northern margin of Gondwana in the Permian continued to drift northwards; the Paleo-Tethys Ocean closing in front of them and the Neo-Tethys opening behind.<ref name=":3" />

Eruptions of the [[Siberian Traps]] [[Large igneous province|Large Igneous Province]] (LIP) persisted into the Early Triassic<ref name=":1" /> and the [[Central Atlantic magmatic province|Central Atlantic Magmatic Province]] (CAMP) were active by the Late Triassic as a prelude to [[seafloor spreading]] in the Central Atlantic at the boundary of the Triassic and Jurassic.<ref name=":6">{{Cite journal |last1=Peace |first1=Alexander L. |last2=Phethean |first2=J. J. J. |last3=Franke |first3=D. |last4=Foulger |first4=G. R. |last5=Schiffer |first5=C. |last6=Welford |first6=J. K. |last7=McHone |first7=G. |last8=Rocchi |first8=S. |last9=Schnabel |first9=M. |last10=Doré |first10=A. G. |date=2020-07-01 |title=A review of Pangaea dispersal and Large Igneous Provinces – In search of a causative mechanism |url=https://www.sciencedirect.com/science/article/pii/S0012825219304817 |journal=Earth-Science Reviews |series=A new paradigm for the North Atlantic Realm |volume=206 |article-number=102902 |doi=10.1016/j.earscirev.2019.102902 |bibcode=2020ESRv..20602902P |issn=0012-8252}}</ref>

=== Northern Pangea (Laurussia) ===
In northern-eastern Pangea, the Siberian Traps LIP continued to erupt into the Middle Triassic. Lower Triassic major deltaic systems (including the [[Triassic Boreal Ocean Delta Plain|Triassic Boreal Ocean delta plain]])<ref>{{Cite journal |author1=Tore Grane Klausen |author2=Björn Nyberg |author3=William Helland-Hansen |date=2019-03-22 |title=The largest delta plain in Earth's history |url=https://pubs.geoscienceworld.org/gsa/geology/article/47/5/470/569564/The-largest-delta-plain-in-Earth-s-history |journal=Geology |volume=47 |issue=5 |pages=470–474 |bibcode=2019Geo....47..470K |doi=10.1130/G45507.1 |access-date=2025-05-25|doi-access=free }}</ref> advanced across the shallow [[Arctic Ocean]]. Their [[Drainage basin|catchment areas]] the high ground of the [[Ural Mountains|Urals]], [[Fennoscandia|Fennoscandinavia]], the Canada-Greenland Shield and the Lomonosov High.<ref name=":1" /> During the Late Triassic, in response to the opening of the Central Atlantic to the south, tectonic movements between North America and [[Baltica]] led to convergence in the High Arctic with uplift, folding and thrusting in the [[Barents Sea]] and North Siberian margin.<ref name=":1" />

Major [[Extensional tectonics|extensional tectonic]] movements, that began in the late Permian, continued across Laurussia from North/Central Europe in the east to eastern Canada in the west, with north-south trending graben systems developing across Europe, including further subsidence in the Northern and Southern [[Permian Basin (Europe)|Permian basins]].<ref name=":1" /><ref name=":4" /> Lower Triassic sediments deposited in these basins are continental to brackish marine in nature. They are overlain by shallow marine [[Carbonate rock|carbonates]] and [[Mudstone|mudstones]] and [[Evaporite|evaporites]] of the [[Zechstein|Zechstein Sea]].<ref name=":1" />

Further south, during the Norian, the opening of the Central Atlantic led to the formation of narrow, deep water basins in the Eastern Mediterranean area.<ref name=":1" /> [[Corsica]], [[Sardinia]], [[Calabria]], and the [[Balearic Islands|Balearic]] terranes were attached to Europe, whilst [[Apulia]], Adria, and the terranes of southern [[Turkey]] remained attached to the [[African plate]].<ref name=":4" />

Along the western margin of Laurussia, a continental [[Volcanic arc|magmatic arc]] extended from the southwestern United States to the Arctic with an associated continental-scale [[foreland basin]] system. Localised [[Back-arc basin|back-arc basins]] developed within this, in regions of extension.<ref>{{Cite journal |last1=Hadlari |first1=Thomas |last2=Midwinter |first2=Derrick |last3=Poulton |first3=Terry P. |last4=Matthews |first4=William A. |date=2017-04-13 |title=A Pangean rim of fire: Reviewing the Triassic of western Laurentia |journal=Lithosphere |volume=9 |issue=4 |pages=579–582 |doi=10.1130/L643.1 |issn=1941-8264|doi-access=free }}</ref> Along the northern section of the margin, the Permian to Early Triassic counterclockwise rotation of Pangea resulted in the closure of the narrow [[Slide Mountain Ocean]] and the [[Sonoma orogeny]].<ref name=":1" /><ref name=":7">{{Cite journal |last1=Riel |first1=Nicolas |last2=Jaillard |first2=Etienne |last3=Martelat |first3=Jean-Emmanuel |last4=Guillot |first4=Stéphane |last5=Braun |first5=Jean |date=2018-01-01 |title=Permian-Triassic Tethyan realm reorganization: Implications for the outward Pangea margin |url=https://www.sciencedirect.com/science/article/pii/S0895981117302535 |journal=Journal of South American Earth Sciences |volume=81 |pages=78–86 |doi=10.1016/j.jsames.2017.11.007 |bibcode=2018JSAES..81...78R |issn=0895-9811|url-access=subscription }}</ref> In south, it led to a reduction in the dip of the subducting slab and thickening of the [[continental crust]].<ref name=":7" />

=== Southern Pangea (Gondwana) ===
Much of Africa was stable and above sea level, with only a few Triassic-aged lake sediments known, although along the northern coast marine sediments were deposited during periods of higher sea levels.<ref name=":1" />

Northeast-southwest trending rifting along the eastern edge of Africa between [[Madagascar]] ([[Indian plate]]) and eastern Africa ([[Somali plate|Somalian plate]]) continued from the Late Carboniferous into the Triassic, with substantial mountains rising along the edge of the rift and the formation of a series of [[Pull-apart basin|pull-apart basins]]. Gradual marine incursions from the Neo-Tethys resulted in the deposition of Lower and Middle Triassic marine sediments in these basins. Upper Triassic sediments are continental in nature and this [[Rift|rift system]] ultimately failed and a new north-south trending rift system developed in the Jurassic.<ref name=":1" /><ref name=":8">{{Cite journal |last1=Frizon de Lamotte |first1=Dominique |last2=Fourdan |first2=Brendan |last3=Leleu |first3=Sophie |last4=Leparmentier |first4=François |last5=de Clarens |first5=Philippe |date=2015 |title=Style of rifting and the stages of Pangea breakup |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/2014TC003760 |journal=Tectonics |language=en |volume=34 |issue=5 |pages=1009–1029 |doi=10.1002/2014TC003760 |bibcode=2015Tecto..34.1009F |issn=1944-9194}}</ref>

The opening of the Neo-Tethys created [[Passive margin|passive margins]] along the Arabian and Indian margins.<ref name=":1" /><ref>{{Cite journal |last1=Madanipour |first1=Saeed |last2=Najafi |first2=Mahdi |last3=Nozaem |first3=Reza |last4=Vergés |first4=Jaume |last5=Yassaghi |first5=Ali |last6=Heydari |first6=Iraj |last7=Khodaparast |first7=Sedigheh |last8=Soudmand |first8=Zahra |last9=Aghajari |first9=Lotfollah |date=2024 |title=The Arabia – Eurasia Collision Zone in Iran: Tectonostratigraphic and Structural Synthesis |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jpg.12854 |journal=Journal of Petroleum Geology |language=en |volume=47 |issue=2 |pages=123–171 |doi=10.1111/jpg.12854 |bibcode=2024JPetG..47..123M |issn=1747-5457|url-access=subscription }}</ref> Rifting in the Neo-Tethys extended westwards between the [[Pontic Mountains|Pontides]] and [[Taurus Mountains|Taurides]] terranes of Turkey during the Late Triassic.<ref name=":1" /> The Tethyan Himalayan block remained attached to India but was separated by the thinned crust of Greater India, the northern margin of which supplied sediments to the passive margin.<ref>{{Cite journal |last1=Cao |first1=Huawen |last2=Huang |first2=Yong |last3=Li |first3=Guangming |last4=Zhang |first4=Linkui |last5=Wu |first5=Jianyang |last6=Dong |first6=Lei |last7=Dai |first7=Zuowen |last8=Lu |first8=Liu |date=2018-01-01 |title=Late Triassic sedimentary records in the northern Tethyan Himalaya: Tectonic link with Greater India |url=https://www.sciencedirect.com/science/article/pii/S167498711730052X |journal=Geoscience Frontiers |series=Lid Tectonics |volume=9 |issue=1 |pages=273–291 |doi=10.1016/j.gsf.2017.04.001 |bibcode=2018GeoFr...9..273C |issn=1674-9871|doi-access=free }}</ref>

The counterclockwise rotation of Pangea precipitated [[Fault (geology)|dextral]] [[transpression]] across the NNE-SSW trending, west-dipping subduction zone, along the eastern Australian margin, which culminated in the [[Hunter–Bowen orogeny|Hunter-Bowen orogeny]] (c. 260-230 Ma).<ref name=":5" /><ref name=":9">{{Cite journal |last=Rosenbaum |first=Gideon |date=2018-05-30 |title=The Tasmanides: Phanerozoic Tectonic Evolution of Eastern Australia |url=https://www.annualreviews.org/content/journals/10.1146/annurev-earth-082517-010146 |journal=Annual Review of Earth and Planetary Sciences |language=en |volume=46 |pages=291–325 |doi=10.1146/annurev-earth-082517-010146 |bibcode=2018AREPS..46..291R |issn=0084-6597}}</ref> Following this, the magmatic arc rotated to north-south and compression gave way to extension. This was accompanied by [[Subduction|subduction rollback]] and back-arc basin formation.<ref name=":5" /><ref name=":9" />

Along the southwestern margin of [[South American plate|South America]], low plate convergence and subduction rates, triggered by the assembly and rotation of Pangea, resulted in subduction rollback and extension across the back-arc region. This generated large amounts of [[felsic]] [[magmatism]].<ref>{{Cite journal |last1=del Rey |first1=Álvaro |last2=Deckart |first2=Katja |last3=Planavsky |first3=Noah |last4=Arriagada |first4=César |last5=Martínez |first5=Fernando |date=2019-12-01 |title=Tectonic evolution of the southwestern margin of Pangea and its global implications: Evidence from the mid Permian–Triassic magmatism along the Chilean-Argentine border |url=https://www.sciencedirect.com/science/article/pii/S1342937X19301571 |journal=Gondwana Research |volume=76 |pages=303–321 |doi=10.1016/j.gr.2019.05.007 |bibcode=2019GondR..76..303D |issn=1342-937X|url-access=subscription }}</ref><ref name=":5" /> These extensional forces stretched across the continent with the formation of large northwest-trending basins with thick sedimentary deposits and the extension related magmatism.<ref name=":1" />

=== Closure of the Paleo-Tethys ===
The Paleo-Tethys ocean formed as the continents surrounding it assembled to form Pangea in the Late Palaeozoic.<ref>{{Cite journal |last1=Şengör |first1=A. M. Celâl |last2=Altıner |first2=Demir |last3=Zabcı |first3=Cengiz |last4=Sunal |first4=Gürsel |last5=Lom |first5=Nalan |last6=Aylan |first6=Eşref |last7=Öner |first7=Tayfun |date=2023-12-01 |title=On the nature of the Cimmerian Continent |url=https://www.sciencedirect.com/science/article/pii/S001282522300209X |journal=Earth-Science Reviews |volume=247 |article-number=104520 |doi=10.1016/j.earscirev.2023.104520 |bibcode=2023ESRv..24704520S |issn=0012-8252|doi-access=free }}</ref> The Eurasian sector of Pangea lay along its north and northwestern margin.<ref name=":1" /> To the northeast, the narrow Paleoasian Ocean (a branch of the Paleo-Tethys) lay between Eurasia, and North China and Tarim, and to the east, South China and Annamia (Southeast Asia). To the south were the Cimmerian terranes (Central Iran, [[Qiangtang terrane|Qiangtang]](north Tibet), [[Lhasa terrane|Lhasa]] (south Tibet), and [[Shan–Thai terrane|Sibumasu]] (eastern Myanmar, Thailand, Malay peninsula and Sumatra). These terranes had rifted from northeastern Gondwana during the Permian. As they drifted northwards through the Triassic, the Paleo-Tethys closed in front of them, and the Neotethys opened behind.<ref name=":1" /><ref name=":3" />

The Paleo-Tethys was being consumed by subduction zones along the southern margin of North China, much of the Eurasian margin, and along the northern margin of the Qiangtang-Annamia and Lhasa-Sibumasu blocks.<ref name=":1" /><ref name=":3" />

Collisions between Annamia and South China (c. 246-230 Ma); between Sibumasu and South China–Annamia (c. 240-230 Ma); and, between Qiangtang and Lhasa (c. 250–230 Ma) resulted in the Indosinian orogeny and the formation of a single large Eastern Asian continent.<ref name=":3" /> At about the same time (c. 240-230 Ma), the final closure of the Paleoasian Ocean led to the collision of Tarim and North China with the Kazakhstan and Siberian regions of Pangea, to form the [[Central Asian Orogenic Belt|Central Asian orogenic belt]].<ref name=":3" /> South China collided with North China (c. 220 Ma), forming the Central China orogenic belt.<ref name=":3" /> The segment of the Paleo-Tethys between North China and Qiangtang may never have fully closed, but was filled with Permo-Triassic turbidites preserved in the West Kunlun and Bayanhar belts of the Central China orogenic belt.<ref>{{Cite journal |last1=Dong |first1=Yunpeng |last2=Sun |first2=Shengsi |last3=Santosh |first3=M. |last4=Zhao |first4=Jie |last5=Sun |first5=Jiaopeng |last6=He |first6=Dengfeng |last7=Shi |first7=Xiaohui |last8=Hui |first8=Bo |last9=Cheng |first9=Chao |last10=Zhang |first10=Guowei |date=2021-12-01 |title=Central China Orogenic Belt and amalgamation of East Asian continents |url=https://www.sciencedirect.com/science/article/pii/S1342937X21000903 |journal=Gondwana Research |series=SPECIAL ISSUE: GR-100 |volume=100 |pages=131–194 |doi=10.1016/j.gr.2021.03.006 |bibcode=2021GondR.100..131D |issn=1342-937X|url-access=subscription }}</ref>

The amalgamation of these East Asian blocks with Pangea in the Late Triassic maximised the land area of the supercontinent. It coincided with a period of dramatic climate change and the development of the megamonsoon, although the relationship between these is the subject of ongoing research.<ref name=":3" />

The western Paleo-Tethys remained open until about 205 Ma, when the Iranian blocks collided with the Turan platform, on the southern margin of Eurasia, resulting in the Cimmerian orogeny. This extended from the [[Anatolian plateau|Anatolian Plateau]] in the northwest, and merged with the Indosinian orogenic belt in the east.<ref name=":1" /><ref>{{Cite journal |last1=Madanipour |first1=Saeed |last2=Najafi |first2=Mahdi |last3=Nozaem |first3=Reza |last4=Vergés |first4=Jaume |last5=Yassaghi |first5=Ali |last6=Heydari |first6=Iraj |last7=Khodaparast |first7=Sedigheh |last8=Soudmand |first8=Zahra |last9=Aghajari |first9=Lotfollah |date=2024 |title=The Arabia – Eurasia Collision Zone in Iran: Tectonostratigraphic and Structural Synthesis |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jpg.12854 |journal=Journal of Petroleum Geology |language=en |volume=47 |issue=2 |pages=123–171 |doi=10.1111/jpg.12854 |bibcode=2024JPetG..47..123M |issn=1747-5457|url-access=subscription }}</ref> Late Triassic deformation across the Eastern Mediterranean area and much of the Middle East was complex, with regional scale [[Fault (geology)|strike-slip faulting]] and continued subduction below the Iranian margin.<ref name=":1" />

=== Opening of the Central Atlantic ===
Beginning in the latest Permian, a broad zone of [[Lithosphere|lithospheric]] extension developed across Pangea along the line of the future Central Atlantic Ocean.<ref name=":6" /><ref name=":10">{{Cite journal |last1=Leleu |first1=Sophie |last2=Hartley |first2=Adrian J. |last3=van Oosterhout |first3=Cees |last4=Kennan |first4=Lorcan |last5=Ruckwied |first5=Katrin |last6=Gerdes |first6=Keith |date=2016-07-01 |title=Structural, stratigraphic and sedimentological characterisation of a wide rift system: The Triassic rift system of the Central Atlantic Domain |url=https://www.sciencedirect.com/science/article/pii/S0012825216300538 |journal=Earth-Science Reviews |volume=158 |pages=89–124 |doi=10.1016/j.earscirev.2016.03.008 |bibcode=2016ESRv..158...89L |hdl=2164/8901 |issn=0012-8252|url-access=subscription }}</ref> The location of this rifting followed the pre-existing structures of the [[Variscan orogeny]], and began immediately after the [[orogenic collapse]] of the Variscan belt.<ref name=":6" /><ref name=":8" /> Extension began in the northern Central Atlantic region in the Anisian, and in the southern Central Atlantic in the Carnian.<ref name=":6" /><ref name=":10" />

Major rift basins formed along the present-day eastern North American margin from Florida to Newfoundland ([[Newark Supergroup]] basins), and along the Europe/African margin (Moroccan and Iberian basins). The Moroccan basins are the equivalent of Nova Scotian basins, and the Iberian the equivalent of the Newfoundland basins.<ref name=":10" /> These basins formed broad depressions on the continental crust that extended for hundreds of kilometres across central Pangea, with localised faulting formed sub-basins.<ref name=":8" /> The basins were filled by mainly continental deposits from regional-scale river systems and lakes, with only minor, late marine incursions in some areas.<ref name=":10" /><ref name=":8" />

The period of rifting came to an end with the emplacement of the Central Atlantic Magmatic Province (CAMP) around 201 Ma. This was followed by seafloor spreading and the opening of the Central Atlantic Ocean.<ref name=":6" /> The CAMP is one of the largest LIPs and covered a region of about 10 million km<sup>2</sup> across North America, northeastern South America, northwestern Africa, and southwestern Europe.<ref name=":1" /><ref name=":6" /> The magmatism produced dense [[Dike swarm|dyke swarms]], with individual dykes up to 800 km long, massive [[Sill (geology)|sill complexes]], and [[Lava field|lava fields]] that covered several hundred kilometres.<ref name=":11">{{Cite book |last1=Marzoli |first1=Andrea |chapter=The Central Atlantic Magmatic Province (CAMP): A Review |date=2018 |title=The Late Triassic World: Earth in a Time of Transition |pages=91–125 |editor-last=Tanner |editor-first=Lawrence H. |chapter-url=https://doi.org/10.1007/978-3-319-68009-5_4 |access-date=2025-06-25 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-68009-5_4 |isbn=978-3-319-68009-5 |last2=Callegaro |first2=Sara |last3=Dal Corso |first3=Jacopo |last4=Davies |first4=Joshua H. F. L. |last5=Chiaradia |first5=Massimo |last6=Youbi |first6=Nassrrdine |last7=Bertrand |first7=Hervé |last8=Reisberg |first8=Laurie |last9=Merle |first9=Renaud}}</ref> Despite its size, the period of magmatism was brief, lasting only about 1 million years. Such intense igneous activity indicates widespread [[Mantle (geology)|mantle]] melting, rather than a simple [[Mantle plume|plume]] within the mantle. The varied [[Petrology|petrological]] composition of the CAMP magmatism reflects local contamination of the upper mantle by continental lithosphere, including partial melting of previously subducted slabs.<ref name=":6" /><ref name=":11" /> The magmatism, with its large scale injection of carbon and sulphur into the atmosphere, precipitated [[Volcanic winter|volcanic winters]]. This was followed by longer-term climate warming and [[ocean acidification]], which caused  the end-Triassic mass extinction.<ref name=":6" /><ref>{{Cite journal |last1=Kent |first1=Dennis V. |last2=Olsen |first2=Paul E. |last3=Wang |first3=Huapei |last4=Schaller |first4=Morgan F. |last5=Et-Touhami |first5=Mohammed |date=2024-11-12 |title=Correlation of sub-centennial-scale pulses of initial Central Atlantic Magmatic Province lavas and the end-Triassic extinctions |journal=Proceedings of the National Academy of Sciences |volume=121 |issue=46 |article-number=e2415486121 |doi=10.1073/pnas.2415486121 |pmc=11573653 |pmid=39467154|bibcode=2024PNAS..12115486K }}</ref><ref name=":11" />

=== Panthalassic Ocean ===
Although no direct evidence remains, Panthalassa is thought to have been divided into three major tectonic plates: the [[Farallon plate|Farallon]]; [[Izanagi plate|Izanagi]]; and, [[Phoenix plate|Phoenix]]. These were separated by oceanic spreading ridges. In the northeast, the smaller Cache Creek plate was being subducted beneath the western margin of North America, and beneath the Farallon plate to the south.<ref name=":1" />[[File:(1)Saunders Quarry-1.jpg|thumb|left|[[Sydney]], [[Australia]] lies on Triassic [[shale]]s and sandstones. Almost all of the exposed rocks around Sydney belong to the Triassic [[Sydney sandstone]].<ref>{{cite book |last1=Herbert |first1=Chris |last2=Helby |first2=Robin |year=1980 |title=A Guide to the Sydney basin |publisher=Geological Survey of NSW |page=582 |location=Maitland, NSW |isbn=978-0-7240-1250-3}}</ref>]]
=== Paleooceanography ===
[[Eustatic sea level]] in the Triassic was consistently low compared to the other geological periods. The beginning of the Triassic was around present sea level, rising to about {{convert|10|–|20|m|0}} above present-day sea level during the Early and Middle Triassic. Sea level rise accelerated in the Ladinian, culminating with a sea level up to {{convert|50|m|0}} above present-day levels during the Carnian. Sea level began to decline in the Norian, reaching a low of {{convert|50|m|0}} below present sea level during the mid-Rhaetian. Low global sea levels persisted into the earliest Jurassic. The long-term sea level trend is superimposed by 22 sea level drop events widespread in the geologic record, mostly of minor (less than {{convert|25|m|0|adj=on}}) and medium ({{convert|25|–|75|m|0|adj=on}}) magnitudes. A lack of evidence for Triassic continental ice sheets suggest that glacial eustasy is unlikely to be the cause of these changes.<ref name="Eustatic">{{Cite journal|last=Haq |first=Bilal U. |author-link=Bilal U. Haq |date=December 2018 |title=Triassic eustatic variations reexamined |journal=GSA Today |publisher=[[Geological Society of America]] |volume=28 |issue=12 |pages=4–9 |doi=10.1130/GSATG381A.1 |bibcode=2018GSAT...28l...4H |s2cid=134477691 |url=https://www.geosociety.org/gsatoday/science/G381A/article.htm|doi-access=free }}</ref> It has generally been assumed that the cause was changes in volume of the global ocean basin due to variations in oceanic volcanism, with largest volumes occurring in volcanism's absence when the ocean basins were subsiding.<ref>{{cite conference|editor-first1=Cheryl K.|editor-last1=Wilgus|editor-first2=Bruce S.|editor-last2=Hastings|editor-first3=Henry|editor-last3=Posamentier|editor-first4=John|editor-last4=van Wagoner|editor-first5=Charles A.|editor-last5=Ross|editor-first6=Christopher G. St. C.|editor-last6=Kendall |last=Embry |first=Ashton F. |chapter=Triassic Sea-Level Changes: Evidence from the Canadian Arctic Archipelago |title=Sea-Level Changes: An Integrated Approach|pages=249–259|publisher=Geological Survey of Canada|year=1985|location=[[Calgary]], [[Alberta]]}}</ref> Variation in water and sediment delivery to the oceans, with higher sea levels during pluvial eras lasting up to four million years, is also hypothesised to be behind these sea level variations.<ref name="Eustatic"/>

==Climate==
The Triassic continental interior climate was generally hot and dry, so that typical deposits are [[red beds|red bed]] [[sandstone]]s and [[evaporite]]s. There is no evidence of [[glacier|glaciation]] at or near either pole; in fact, the polar regions were apparently moist and [[temperate]], providing a climate suitable for forests and vertebrates, including reptiles. Pangaea's large size limited the moderating effect of the global ocean; its [[continental climate]] was highly seasonal, with very hot summers and cool winters.<ref name="Stanley, 452-3">Stanley, 452–53.</ref> The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial [[monsoons]],<ref name="Stanley, 452-3"/> sometimes referred to as the [[Pangean megamonsoon]]s.<ref>{{cite journal |last1=Zeng |first1=Zhiwei |last2=Zhu |first2=Hongtao |last3=Yang |first3=Xianghua |last4=Zeng |first4=Hongliu |last5=Hu |first5=Xiaolin |last6=Xia |first6=Chenchen |date=May 2019 |title=The Pangaea Megamonsoon records: Evidence from the Triassic Mungaroo Formation, Northwest Shelf of Australia |url=https://www.sciencedirect.com/science/article/abs/pii/S1342937X19300127 |journal=[[Gondwana Research]] |volume=69 |pages=1–24 |doi=10.1016/j.gr.2018.11.015 |bibcode=2019GondR..69....1Z |s2cid=134145664 |access-date=9 January 2023|url-access=subscription }}</ref>

The Triassic may have mostly been a dry period, but evidence exists that it was punctuated by several episodes of increased rainfall in tropical and subtropical latitudes of the Tethys Sea and its surrounding land.<ref name=Pretoetal2010>{{cite journal |last1=Preto |first1=N. |last2=Kustatscher |first2=E. |last3=Wignall |first3=P. B. |year=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}}</ref> Sediments and fossils suggestive of a more humid climate are known from the Anisian to Ladinian of the Tethysian domain, and from the Carnian and Rhaetian of a larger area that includes also the Boreal domain (e.g., [[Svalbard]] Islands), the [[North America]]n continent, the South [[China]] block and [[Argentina]]. The best-studied of such episodes of humid climate, and probably the most intense and widespread, was the [[Carnian Pluvial Event]]. 

=== Early Triassic ===
The Early Triassic was the hottest portion of the entire Phanerozoic, seeing as it occurred during and immediately after the discharge of titanic volumes of [[greenhouse gas]]es from the Siberian Traps. The Early Triassic began with the [[Permian]]-Triassic Thermal Maximum (PTTM) and was followed by the brief [[Dienerian]] Cooling (DC) from 251 to 249 Ma, which was in turn followed by the Latest [[Olenekian|Smithian]] Thermal Maximum (LSTT) around 249 to 248 Ma. During the Latest [[Olenekian]] Cooling (LOC), from 248 to 247 Ma, temperatures cooled by about 6 °C.<ref name="ChristopherRobertScotese">{{Cite journal |last1=Scotese |first1=Christopher Robert |last2=Song |first2=Haijun |last3=Mills |first3=Benjamin J. W. |last4=van der Meer |first4=Douwe G. |date=1 April 2021 |title=Phanerozoic paleotemperatures: The earth's changing climate during the last 540 million years |url=https://www.sciencedirect.com/science/article/pii/S0012825221000027 |journal=[[Earth-Science Reviews]] |volume=215 |article-number=103503 |doi=10.1016/j.earscirev.2021.103503 |bibcode=2021ESRv..21503503S |s2cid=233579194 |issn=0012-8252 |access-date=22 September 2023|url-access=subscription }}</ref>

=== Middle Triassic ===
The Middle Triassic was cooler than the Early Triassic, with temperatures falling over most of the Anisian, with the exception of a warming spike in the latter portion of the stage.<ref>{{Cite journal |last1=Trotter |first1=Julie A. |last2=Williams |first2=Ian S. |last3=Nicora |first3=Alda |last4=Mazza |first4=Michele |last5=Rigo |first5=Manuel |date=April 2015 |title=Long-term cycles of Triassic climate change: a new δ18O record from conodont apatite |url=https://linkinghub.elsevier.com/retrieve/pii/S0012821X15000667 |journal=[[Earth and Planetary Science Letters]] |language=en |volume=415 |pages=165–174 |doi=10.1016/j.epsl.2015.01.038 |bibcode=2015E&PSL.415..165T |access-date=22 September 2023|url-access=subscription }}</ref> From 242 to 233 Ma, the Ladinian-Carnian Cooling (LCC) ensued.<ref name="ChristopherRobertScotese" /> 

=== Late Triassic ===
At the beginning of the Carnian, global temperatures continued to be relatively cool.<ref>{{Cite journal |last1=Dal Corso |first1=Jacopo |last2=Mills |first2=Benjamin J.W. |last3=Chu |first3=Daoliang |last4=Newton |first4=Robert J. |last5=Song |first5=Haijun |date=15 January 2022 |title=Background Earth system state amplified Carnian (Late Triassic) environmental changes |url=https://linkinghub.elsevier.com/retrieve/pii/S0012821X2100577X |journal=[[Earth and Planetary Science Letters]] |language=en |volume=578 |article-number=117321 |doi=10.1016/j.epsl.2021.117321 |bibcode=2022E&PSL.57817321D |s2cid=244847207 |access-date=22 September 2023|url-access=subscription }}</ref> The eruption of the Wrangellia Large Igneous Province around 234 Ma caused abrupt global warming, terminating the cooling trend of the LCC.<ref>{{Cite journal |last1=Dal Corso |first1=J. |last2=Mietto |first2=P. |last3=Newton |first3=R. J. |last4=Pancost |first4=R. D. |last5=Preto |first5=N. |last6=Roghi |first6=G. |last7=Wignall |first7=P. B. |date=1 January 2012 |title=Discovery of a major negative 13C spike in the Carnian (Late Triassic) linked to the eruption of Wrangellia flood basalts |url=https://pubs.geoscienceworld.org/geology/article/40/1/79-82/130736 |journal=[[Geology (journal)|Geology]] |language=en |volume=40 |issue=1 |pages=79–82 |doi=10.1130/G32473.1 |bibcode=2012Geo....40...79D |issn=0091-7613 |access-date=22 September 2023|url-access=subscription }}</ref> This warming was responsible for the Carnian Pluvial Event and resulted in an episode of widespread global humidity.<ref>{{Cite journal |last1=Li |first1=Liqin |last2=Kürschner |first2=Wolfram M. |last3=Lu |first3=Ning |last4=Chen |first4=Hongyu |last5=An |first5=Pengcheng |last6=Wang |first6=Yongdong |date=September 2022 |title=Palynological record of the Carnian Pluvial Episode from the northwestern Sichuan Basin, SW China |url=https://linkinghub.elsevier.com/retrieve/pii/S0034666722001026 |journal=[[Review of Palaeobotany and Palynology]] |language=en |volume=304 |article-number=104704 |doi=10.1016/j.revpalbo.2022.104704 |bibcode=2022RPaPa.30404704L |s2cid=249528886 |access-date=22 September 2023|hdl=10852/99190 |hdl-access=free }}</ref> The CPE ushered in the Mid-Carnian Warm Interval (MCWI), which lasted from 234 to 227 Ma.<ref name="ChristopherRobertScotese" /> At the Carnian-Norian boundary occurred a positive [[Δ13C|δ<sup>13</sup>C]] excursion believed to signify an increase in organic carbon burial.<ref>{{Cite journal |last1=Muttoni |first1=Giovanni |last2=Mazza |first2=Michele |last3=Mosher |first3=David |last4=Katz |first4=Miriam E. |last5=Kent |first5=Dennis V. |last6=Balini |first6=Marco |date=1 April 2014 |title=A Middle–Late Triassic (Ladinian–Rhaetian) carbon and oxygen isotope record from the Tethyan Ocean |url=https://www.sciencedirect.com/science/article/pii/S0031018214000285 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=399 |pages=246–259 |doi=10.1016/j.palaeo.2014.01.018 |bibcode=2014PPP...399..246M |issn=0031-0182 |access-date=24 November 2023|url-access=subscription }}</ref> From 227 to 217 Ma, there was a relatively cool period known as the Early Norian Cool Interval (ENCI), after which occurred the Mid-Norian Warm Interval (MNWI) from 217 to 209 Ma. The MNWI was briefly interrupted around 214 Ma by a cooling possibly related to the [[Manicouagan Impact Crater|Manicouagan impact]].<ref name="ChristopherRobertScotese" /> Around 212 Ma, a 10 Myr eccentricity maximum caused a paludification of Pangaea and a reduction in the size of arid climatic zones.<ref>{{Cite journal |last1=Ikeda |first1=Masayuki |last2=Ozaki |first2=Kazumi |last3=Legrand |first3=Julien |date=23 July 2020 |title=Impact of 10-Myr scale monsoon dynamics on Mesozoic climate and ecosystems |journal=[[Scientific Reports]] |language=en |volume=10 |issue=1 |page=11984 |doi=10.1038/s41598-020-68542-w |pmid=32704030 |pmc=7378230 |bibcode=2020NatSR..1011984I |issn=2045-2322 }}</ref> The Rhaetian Cool Interval (RCI) lasted from 209 to 201 Ma.<ref name="ChristopherRobertScotese" /> At the terminus of the Triassic, there was an extreme warming event referred to as the End-Triassic Thermal Event (ETTE), which was responsible for the Triassic-Jurassic mass extinction.<ref name="ChristopherRobertScotese" /> Bubbles of [[carbon dioxide]] in basaltic rocks dating back to the end of the Triassic indicate that volcanic activity from the Central Atlantic Magmatic Province helped trigger climate change in the ETTE.<ref>{{Cite journal |last1=Capriolo |first1=Manfredo |last2=Marzoli |first2=Andrea |last3=Aradi |first3=László E. |last4=Callegaro |first4=Sara |last5=Dal Corso |first5=Jacopo |last6=Newton |first6=Robert J. |last7=Mills |first7=Benjamin J. W. |last8=Wignall |first8=Paul B. |last9=Bartoli |first9=Omar |last10=Baker |first10=Don R. |last11=Youbi |first11=Nasrrddine |last12=Remusat |first12=Laurent |last13=Spiess |first13=Richard |last14=Szabó |first14=Csaba |date=7 April 2020 |title=Deep CO2 in the end-Triassic Central Atlantic Magmatic Province |journal=[[Nature Communications]] |language=en |volume=11 |issue=1 |page=1670 |doi=10.1038/s41467-020-15325-6 |issn=2041-1723 |pmc=7138847 |pmid=32265448 |bibcode=2020NatCo..11.1670C }}</ref>

== Flora ==
[[File:Triassic plants MKL Bd. 15 1890 (128662915).jpg|thumb|upright|left|Triassic flora as depicted in {{Lang|de|[[Meyers Konversations-Lexikon]]}} (1885–90)]]

=== Land plants ===
During the Early Triassic, [[Lycophyte|lycophytes]], particularly those of the order [[Isoetales]] (which contains living [[Quillwort|quillworts]]), rose to prominence due to the environmental instability following the Permian-Triassic extinction, with one particularly notable example being the genus ''[[Pleuromeia]],'' which grew in columnar like fashion, sometimes reaching a height of {{Convert|2|m|ft}}. The relevance of lycophytes declined from the Middle Triassic onwards, following the return of more stable environmental conditions.<ref>{{Cite journal |last1=Looy |first1=Cindy V. |last2=van Konijnenburg-van Cittert |first2=Johanna H. A. |last3=Duijnstee |first3=Ivo A. P. |date=2021-03-02 |title=Proliferation of Isoëtalean Lycophytes During the Permo-Triassic Biotic Crises: A Proxy for the State of the Terrestrial Biosphere |journal=Frontiers in Earth Science |volume=9 |page=55 |article-number=615370 |doi=10.3389/feart.2021.615370 |doi-access=free |bibcode=2021FrEaS...9...55L |issn=2296-6463}}</ref>

While having first appeared during the Permian, the extinct seed plant group [[Bennettitales]] first became a prominent element in global floras during the Late Triassic, a position they would hold for much of the Mesozoic.<ref name=":0">{{Cite journal |last1=Blomenkemper |first1=Patrick |last2=Bäumer |first2=Robert |last3=Backer |first3=Malte |last4=Abu Hamad |first4=Abdalla |last5=Wang |first5=Jun |last6=Kerp |first6=Hans |last7=Bomfleur |first7=Benjamin |date=2021 |title=Bennettitalean Leaves From the Permian of Equatorial Pangea—The Early Radiation of an Iconic Mesozoic Gymnosperm Group |journal=Frontiers in Earth Science |volume=9 |page=162 |article-number=652699 |bibcode=2021FrEaS...9..162B |doi=10.3389/feart.2021.652699 |doi-access=free}}</ref> In the Southern Hemisphere landmasses of Gondwana, the tree ''[[Dicroidium]]'', an extinct "[[seed fern]]" belong to the order [[Corystospermales]] was a dominant element in forest habitats across the region during the Middle-Late Triassic.<ref name=":2">{{Cite web |last1=Mays |first1=Chris |last2=McLoughlin |first2=Stephen |date=2020-02-25 |title=Caught between two mass extinctions: The rise and fall of Dicroidium |url=https://depositsmag.com/2020/02/25/caught-between-two-mass-extinctions-the-rise-and-fall-of-dicroidium/ |access-date=2023-09-23 |website=Deposits Mag |language=en-US}}</ref> During the Late Triassic, the [[Ginkgoales]] (which today are represented by only a single species, ''[[Ginkgo biloba]]'') underwent considerable diversification.<ref>{{Cite journal |last=Zhou |first=Zhi-Yan |date=March 2009 |title=An overview of fossil Ginkgoales |url=https://linkinghub.elsevier.com/retrieve/pii/S1871174X0900002X |journal=Palaeoworld |language=en |volume=18 |issue=1 |pages=1–22 |doi=10.1016/j.palwor.2009.01.001|url-access=subscription }}</ref> Conifers were abundant during the Triassic, and included the [[Voltziales]] (which contains various lineages, probably including those ancestral to modern conifers),<ref>{{Cite journal |last1=Forte |first1=Giuseppa |last2=Kustatscher |first2=Evelyn |last3=Van Konijnenburg-van Cittert |first3=Johanna H. A. |date=2021-07-01 |title=Conifer Diversity in the Middle Triassic: New Data from the Fossillagerstätte Kühwiesenkopf/Monte Prà della Vacca (Pelsonian, Anisian) in the Dolomites (Northeastern Italy) |url=https://www.journals.uchicago.edu/doi/10.1086/714280 |journal=International Journal of Plant Sciences |language=en |volume=182 |issue=6 |pages=445–467 |doi=10.1086/714280 |bibcode=2021IJPlS.182..445F |issn=1058-5893|url-access=subscription }}</ref> as well as the extinct family [[Cheirolepidiaceae]], which first appeared in the Late Triassic, and would be prominent throughout most of the rest of the Mesozoic.<ref>{{Cite journal |last1=Escapa |first1=Ignacio |last2=Leslie |first2=Andrew |date=February 2017 |title=A new Cheirolepidiaceae (Coniferales) from the Early Jurassic of Patagonia (Argentina): Reconciling the records of impression and permineralized fossils |url=https://bsapubs.onlinelibrary.wiley.com/doi/10.3732/ajb.1600321 |journal=American Journal of Botany |language=en |volume=104 |issue=2 |pages=322–334 |doi=10.3732/ajb.1600321 |pmid=28213347 |issn=0002-9122|hdl=11336/40738 |hdl-access=free }}</ref>

==== Coal ====
[[File:Prospect Hill Monterey Pine Forest.jpg|thumb|upright=1.2|Immediately above the Permian–Triassic boundary the [[glossopteris]] flora was suddenly<ref>{{cite journal |last1=Hosher |first1=WT Magaritz M Clark D |year=1987 |title=Events near the time of the Permian-Triassic boundary |journal=Mod. Geol. |volume=11 |pages=155–80 [173–74]}}</ref> largely displaced by an [[Australia]]-wide coniferous flora.]]

No known [[coal]] deposits date from the start of the Triassic Period. This is known as the [[Early Triassic]] "coal gap" and can be seen as part of the [[Permian–Triassic extinction event]].<ref name="Retallack1996a">{{cite journal |last1=Retallack |first1=G. J. |last2=Veevers |first2=J. J. |last3=Morante |first3=R. |year=1996 |title=Global coal gap between Permian-Triassic extinction and Middle Triassic recovery of peat-forming plants |journal=Bulletin of the Geological Society of America |volume=108 |issue=2 |pages=195–207 |doi=10.1130/0016-7606(1996)108<0195:GCGBPT>2.3.CO;2 |bibcode=1996GSAB..108..195R}}</ref> Possible explanations for the coal gap include sharp drops in sea level at the time of the Permo-Triassic boundary;<ref>{{cite journal |last1=Holser |first1=WT |last2=Schoenlaub |first2=H-P |last3=Klein |first3=P |last4=Attrep |first4=M |last5=Boeckelmann |first5=Klaus |display-authors=etal |year=1989 |title=A unique geochemical record at the Permian/Triassic boundary |url=https://www.nature.com/articles/337039a0 |journal=[[Nature (journal)|Nature]] |volume=337 |issue=6202 |pages=39 [42] |bibcode=1989Natur.337...39H |doi=10.1038/337039a0 |s2cid=8035040 |access-date=24 November 2023|url-access=subscription }}</ref> acid rain from the Siberian Traps eruptions or from an impact event that overwhelmed acidic swamps; climate shift to a greenhouse climate that was too hot and dry for peat accumulation; evolution of fungi or herbivores that were more destructive of wetlands; the extinction of all plants adapted to peat swamps, with a hiatus of several million years before new plant species evolved that were adapted to peat swamps;<ref name="Retallack1996a"/> or soil anoxia as oxygen levels plummeted.<ref>{{cite journal |last1=Retallack |first1=G.J. |last2=Krull |first2=E.S. |year=2006 |title=Carbon isotopic evidence for terminal-Permian methane outbursts and their role in extinctions of animals, plants, coral reefs, and peat swamps |journal=Geological Society of America Special Paper |volume=399 |page=249 |url=https://cpb-us-e1.wpmucdn.com/blogs.uoregon.edu/dist/d/3735/files/2013/07/ragnarok-15t4q8w.pdf |access-date=14 December 2020 |doi=10.1130/2006.2399(12) |isbn=978-0-8137-2399-0}}</ref>

=== Phytoplankton ===
Before the Permian extinction, [[Archaeplastida]] (red and green algae) had been the major marine [[phytoplankton]]s since about 659–645 million years ago,<ref>{{cite web |url=https://cosmosmagazine.com/geoscience/how-snowball-earth-gave-rise-to-complex-life |title=How snowball Earth gave rise to complex life – Cosmos Magazine |date=16 August 2017}}</ref> when they replaced marine planktonic [[cyanobacteria]], which first appeared about 800 million years ago, as the dominant phytoplankton in the oceans.<ref>{{cite web |url=https://www.bristol.ac.uk/news/2015/december/bacteria-bloom-evolution.html |title=December: Phytoplankton {{!}} News {{!}} University of Bristol |date=December 2015 }}</ref> In the Triassic, [[Symbiogenesis#Secondary endosymbiosis|secondary endosymbiotic]] algae became the most important plankton.<ref>{{cite web |url=https://www.researchgate.net/publication/319952276 |title=The rise of algae in Cryogenian oceans and the emergence of animals – ResearchGate}}</ref>

{{clear}}

== Fauna ==
[[File:Triassic Utah.JPG|thumb|upright=1.2|Middle Triassic marginal marine sequence, southwestern [[Utah]]]]

=== Marine invertebrates ===
In [[Ocean|marine environments]], new modern types of [[coral]]s appeared in the Early Triassic, forming small patches of [[reefs]] of modest extent compared to the great reef systems of [[Devonian]] or modern times. At the end of the Carnian, a reef crisis occurred in South China.<ref>{{Cite journal |last1=Jin |first1=Xin |last2=Shi |first2=Zhiqiang |last3=Rigo |first3=Manuel |last4=Franceschi |first4=Marco |last5=Preto |first5=Nereo |date=15 September 2018 |title=Carbonate platform crisis in the Carnian (Late Triassic) of Hanwang (Sichuan Basin, South China): Insights from conodonts and stable isotope data |url=https://linkinghub.elsevier.com/retrieve/pii/S1367912018302438 |journal=[[Journal of Asian Earth Sciences]] |language=en |volume=164 |pages=104–124 |doi=10.1016/j.jseaes.2018.06.021 |bibcode=2018JAESc.164..104J |s2cid=134733944 |access-date=22 September 2023|url-access=subscription }}</ref> [[Serpulidae|Serpulids]] appeared in the Middle Triassic.<ref name=VinnMutvei2009>{{cite journal |last1=Vinn |first1=O. |last2=Mutvei |first2=H. |year=2009 |title=Calcareous tubeworms of the Phanerozoic |journal=Estonian Journal of Earth Sciences |volume=58 |issue=4 |pages=286–96 |url=http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2009/issue_4/earth-2009-4-286-296.pdf |access-date=2012-09-16 |doi=10.3176/earth.2009.4.07 |doi-access=free|bibcode=2009EsJES..58..286V }}</ref> [[Microconchids]] were abundant. The shelled [[cephalopod]]s called [[ammonite]]s recovered, diversifying from a single line that survived the Permian extinction. Bivalves began to rapidly diversify during the Middle Triassic, becoming highly abundant in the oceans.<ref>{{cite journal |last1=Komatsu |first1=Toshifumi |last2=Chen |first2=Jin-hua |last3=Cao |first3=Mei-zhen |last4=Stiller |first4=Frank |last5=Naruse |first5=Hajime |date=10 June 2004 |title=Middle Triassic (Anisian) diversified bivalves: depositional environments and bivalve assemblages in the Leidapo Member of the Qingyan Formation, southern China |url=https://www.sciencedirect.com/science/article/abs/pii/S0031018204001841 |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=208 |issue=3–4 |pages=227–223 |doi=10.1016/j.palaeo.2004.03.005 |bibcode=2004PPP...208..207K |access-date=31 March 2023|url-access=subscription }}</ref>

=== Insects ===

Aquatic insects rapidly diversified during the Middle Triassic, with this time interval representing a crucial diversification for [[Holometabola]], the clade containing the majority of modern insect species.<ref>{{Cite journal |last1=Zheng |first1=Daran |last2=Chang |first2=Su-Chin |last3=Wang |first3=He |last4=Fang |first4=Yan |last5=Wang |first5=Jun |last6=Feng |first6=Chongqing |last7=Xie |first7=Guwei |last8=Jarzembowski |first8=Edmund A. |last9=Zhang |first9=Haichun |last10=Wang |first10=Bo |date=7 September 2018 |title=Middle-Late Triassic insect radiation revealed by diverse fossils and isotopic ages from China |journal=[[Science Advances]] |language=en |volume=4 |issue=9 |article-number=eaat1380 |doi=10.1126/sciadv.aat1380 |issn=2375-2548 |pmc=6124916 |pmid=30191177 |bibcode=2018SciA....4.1380Z }}</ref>
=== Fish ===
[[File:Birgeria recon.jpg|right|thumb|250px|''[[Birgeria]]'']]
In the wake of the [[end-Permian mass extinction|Permian-Triassic mass extinction event]], the [[fish]] fauna was remarkably uniform, with many [[family (biology)|families]] and [[genera]] exhibiting a [[cosmopolitan distribution]].<ref name=Romano2016>{{cite journal |last1=Romano |first1=Carlo |last2=Koot |first2=Martha B. |last3=Kogan |first3=Ilja |last4=Brayard |first4=Arnaud |last5=Minikh |first5=Alla V. |last6=Brinkmann |first6=Winand |last7=Bucher |first7=Hugo |last8=Kriwet |first8=Jürgen |title=Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution |journal=Biological Reviews |date=February 2016 |volume=91 |issue=1 |pages=106–47 |doi=10.1111/brv.12161 |pmid=25431138 |s2cid=5332637|url=https://hal.science/hal-01253154 }}</ref> [[Coelacanth]]s show their highest post-[[Devonian]] diversity in the [[Early Triassic]].<ref>{{cite journal |last1=Cavin |first1=Lionel |last2=Furrer |first2=Heinz |last3=Obrist |first3=Christian |year=2013 |title=New coelacanth material from the Middle Triassic of eastern Switzerland, and comments on the taxic diversity of actinistans |journal=Swiss Journal of Geoscience |volume=106 |issue=2 |pages=161–177 |doi=10.1007/s00015-013-0143-7 |doi-access=free|bibcode=2013SwJG..106..161C }}</ref> [[Actinopterygians|Ray-finned fishes]] (actinopterygians) went through a remarkable diversification in the beginning of the Triassic, leading to peak diversity during the Middle Triassic; however, the pattern of this diversification is still not well understood due to a [[megabias|taphonomic megabias]].<ref>{{cite journal |last1=Romano |first1=Carlo |title=A hiatus obscures the early evolution of Modern lineages of bony fishes |journal=Frontiers in Earth Science |date=January 2021 |volume=8 |article-number=618853 |doi=10.3389/feart.2020.618853 |doi-access=free|bibcode=2021FrEaS...8.8853R }}</ref> The first [[stem-group]] [[teleost]]s appeared during the Triassic (teleosts are by far the most diverse group of fish today).<ref name=Romano2016/> Predatory actinopterygians such as [[Saurichthys|saurichthyids]] and [[Birgeria|birgeriids]], some of which grew over {{cvt|1.2|m|ft}} in length, appeared in the Early Triassic and became widespread and successful during the period as a whole.<ref name="Romano17">{{cite journal |last1=Romano |first1=Carlo |last2=Jenks |first2=James F. |last3=Jattiot |first3=Romain |last4=Scheyer |first4=Torsten M. |year=2017 |title=Marine Early Triassic Actinopterygii from Elko County (Nevada, USA): implications for the Smithian equatorial vertebrate eclipse |journal=Journal of Paleontology |volume=91 |issue=5 |pages=1–22 |doi=10.1017/jpa.2017.36 |bibcode=2017JPal...91.1025R |doi-access=free}}</ref> Lakes and rivers were populated by [[lungfish]] (Dipnoi), such as ''[[Ceratodus (genus)|Ceratodus]]'', which are mainly known from the dental plates, abundant in the fossils record.<ref>Agnolin, F. L., Mateus O., Milàn J., Marzola M., Wings O., Adolfssen J. S., & Clemmensen L. B. (2018).  Ceratodus tunuensis, sp. nov., a new lungfish (Sarcopterygii, Dipnoi) from the Upper Triassic of central East Greenland. Journal of Vertebrate PaleontologyJournal of Vertebrate Paleontology. e1439834</ref> [[Hybodonts]], a group of shark-like [[cartilaginous fish]], were dominant in both freshwater and marine environments throughout the Triassic.<ref>{{Cite journal |last1=Kumar |first1=Krishna |last2=Bajpai |first2=Sunil |last3=Pandey |first3=Pragya |last4=Ghosh |first4=Triparna |last5=Bhattacharya |first5=Debasish |date=2021-08-04 |title=Hybodont sharks from the Jurassic of Jaisalmer, western India |journal=Historical Biology |volume=34 |issue=6 |pages=953–963 |doi=10.1080/08912963.2021.1954920 |s2cid=238781606 |issn=0891-2963}}</ref> Last survivors of the mainly [[Palaeozoic]] [[Eugeneodontida]] are known from the Early Triassic.<ref>{{cite book |last1=Mutter |first1=Raoul J. |last2=Neuman |first2=Andrew G. |year=2008 |chapter=New eugeneodontid sharks from the Lower Triassic Sulphur Mountain Formation of Western Canada |title=Fishes and the Break-up of Pangaea  |editor1=Cavin, L. |editor2=Longbottom, A. |editor3=Richter, M. |series=Geological Society of London, Special Publications |publisher=Geological Society of London |location=London |volume=295 |pages=9–41 |doi=10.1144/sp295.3|s2cid=130268582 }}</ref>

=== Amphibians ===
[[File:Mastodonsaurus3.jpg|thumb|170px|right|Reconstruction of the Triassic amphibian ''[[Mastodonsaurus]]'']]
[[Temnospondyli|Temnospondyl]] [[amphibian]]s were among those groups that survived the Permian–Triassic extinction. Once abundant in both terrestrial and aquatic environments, the terrestrial species had mostly died out during the extinction event. The Triassic survivors were aquatic or semi-aquatic, and were represented by ''[[Tupilakosaurus]]'', ''[[Thabanchuia]]'', [[Branchiosauridae]] and ''[[Micropholis (amphibian)|Micropholis]]'', all of which died out in Early Triassic, and the successful [[Stereospondyli]], with survivors into the Cretaceous Period. The largest Triassic stereospondyls, such as ''[[Mastodonsaurus]],'' were up to {{convert|4|to|6|m|ft}} in length.<ref>{{Cite book |last=Wells |first=Kentwood D. |url=https://books.google.com/books?id=eDKEKy5JJbIC&q=By+the+Triassic+Period+(245+million+years+ago),+the+temnospondyls&pg=PA8 |title=The Ecology and Behavior of Amphibians |publisher=[[University of Chicago Press]] |year=2010 |isbn=978-0-226-89333-4 |via=Google Books}}</ref><ref>{{Cite book |url=https://books.google.com/books?id=VThUUUtM8A4C&q=At+the+end+of+the+Permian,+the+temnospondyls+largely+died+out&pg=PA97 |title=Vertebrate Palaeontology |first=Michael |last=Benton |date=2009 |publisher=John Wiley & Sons |via=Google Books |isbn=978-1-4051-4449-0}}</ref> Some lineages (e.g. [[trematosaur]]s) flourished briefly in the Early Triassic, while others (e.g. [[capitosaur]]s) remained successful throughout the whole period, or only came to prominence in the Late Triassic (e.g. ''[[Plagiosaurus]]'', [[metoposaur]]s).

The first [[Lissamphibia]]ns (modern amphibians) appear in the Triassic, with the progenitors of the first [[frog]]s already present by the Early Triassic. However, the group as a whole did not become common until the [[Jurassic]], when the temnospondyls had become very rare.

Most of the [[Reptiliomorpha]], stem-amniotes that gave rise to the amniotes, disappeared in the Triassic, but two water-dwelling groups survived: [[Embolomeri]] that only survived into the early part of the period, and the [[Chroniosuchia]], which survived until the end of the Triassic.

=== Reptiles ===
==== Archosauromorphs ====
The Permian–Triassic extinction devastated terrestrial life. Biodiversity rebounded as the [[pioneer organisms|surviving species]] repopulated empty terrain, but these were short-lived. Diverse communities with complex [[food-web]] structures took 30 million years to reestablish.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction" /><ref name="EVOLUTION">{{cite book |author1=Douglas Palmer |author2=Peter Barrett |title=Evolution: The Story of Life |year=2009 |publisher=The Natural History Museum |location=London |isbn=978-1-84533-339-3}}</ref> [[Archosauromorpha|Archosauromorph]] reptiles, which had already appeared and diversified to an extent in the Permian Period, exploded in diversity as an [[adaptive radiation]] in response to the Permian-Triassic mass extinction. By the Early Triassic, several major archosauromorph groups had appeared. Long-necked, lizard-like early archosauromorphs were known as [[Protorosauria|protorosaurs]], which is likely a paraphyletic group rather than a true clade. [[Tanystropheidae|Tanystropheids]] were a family of protorosaurs which elevated their neck size to extremes, with the largest genus ''[[Tanystropheus]]'' having a neck longer than its body. The protorosaur family [[Sharovipterygidae]] used their elongated hindlimbs for gliding. Other archosauromorphs, such as [[rhynchosaur]]s and [[Allokotosauria|allokotosaurs]], were mostly stocky-bodied herbivores with specialized jaw structures.

Rhynchosaurs, barrel-gutted herbivores, thrived for only a short period of time, becoming extinct about 220 million years ago. They were exceptionally abundant in the middle of the Triassic, as the primary large herbivores in many Carnian-age ecosystems. They sheared plants with premaxillary beaks and plates along the upper jaw with multiple rows of teeth. Allokotosaurs were iguana-like reptiles, including ''[[Trilophosaurus]]'' (a common Late Triassic reptile with three-crowned teeth), ''[[Teraterpeton]]'' (which had a long beak-like snout), and ''[[Shringasaurus]]'' (a horned herbivore which reached a body length of {{convert|3–4|m}}).

One group of archosauromorphs, the [[Archosauriformes|archosauriforms]], were distinguished by their active predatory lifestyle, with serrated teeth and upright limb postures. Archosauriforms were diverse in the Triassic, including various terrestrial and semiaquatic predators of all shapes and sizes. The large-headed and robust [[Erythrosuchidae|erythrosuchids]] were among the dominant carnivores in the early Triassic. [[Phytosaurs]] were a particularly common group which prospered during the Late Triassic. These long-snouted and semiaquatic predators resemble living crocodiles and probably had a similar lifestyle, hunting for fish and small reptiles around the water's edge. However, this resemblance is only superficial and is a prime-case of convergent evolution.

True [[archosaur]]s appeared in the early Triassic, splitting into two branches: [[Avemetatarsalia]] (the ancestors to birds) and [[Pseudosuchia]] (the ancestors to crocodilians). Avemetatarsalians were a minor component of their ecosystems, but eventually produced the earliest [[pterosaur]]s and [[dinosaur]]s in the Late Triassic. Early long-tailed pterosaurs appeared in the Norian and quickly spread worldwide. Triassic dinosaurs evolved in the Carnian and include early sauropodomorphs and theropods. Most Triassic dinosaurs were small predators and only a few were common, such as ''[[Coelophysis]]'', which was {{convert|1|to|2|m|ft}} long. Triassic [[Sauropodomorpha|sauropodomorphs]] primarily inhabited cooler regions of the world.<ref>{{cite journal |last1=Dunne |first1=Emma M. |last2=Farnsworth |first2=Alexander |last3=Benson |first3=Roger B. J. |last4=Godoy |first4=Pedro L. |last5=Greene |first5=Sarah E. |last6=Valdes |first6=Paul J. |last7=Lunt |first7=Daniel J. |last8=Butler |first8=Richard J. |date=9 January 2023 |title=Climatic controls on the ecological ascendancy of dinosaurs |journal=[[Current Biology]] |volume=33 |issue=1 |pages=206–214 |doi=10.1016/j.cub.2022.11.064 |pmid=36528026 |s2cid=254754419 |doi-access=free |bibcode=2023CBio...33E.206D |hdl=1983/aea1ae86-2260-4d4d-a9d5-0fe38a0f470e |hdl-access=free }}</ref>

The large predator ''[[Smok (archosaur)|Smok]]'' was most likely also an archosaur, but it is uncertain if it was a primitive dinosaur or a pseudosuchian.

Pseudosuchians were far more ecologically dominant in the Triassic, including large herbivores (such as [[aetosaur]]s), large carnivores ("[[rauisuchia]]ns"), and the first [[crocodylomorphs]] ("[[sphenosuchia]]ns"). [[Aetosaurs]] were heavily-armored reptiles that were common during the last 30 million years of the Late Triassic until they died out at the Triassic-Jurassic extinction. Most aetosaurs were herbivorous and fed on low-growing plants, but some may have eaten meat. "[[rauisuchia]]ns" (formally known as [[Paracrocodylomorpha|paracrocodylomorphs]]) were the keystone predators of most Triassic terrestrial ecosystems. Over 25 species have been found, including giant quadrupedal hunters, sleek bipedal omnivores, and lumbering beasts with deep sails on their backs. They probably occupied the large-predator niche later filled by theropods. "Rauisuchians" were ancestral to small, lightly-built crocodylomorphs, the only pseudosuchians which survived into the Jurassic.

<gallery class="center">
File:Tanystropheus NT small.jpg|''[[Tanystropheus]],'' a long-necked [[Tanystropheidae|tanystropheid]]
File:Proterosuchus BW.jpg|''[[Proterosuchus]]'', a crocodile-like early archosauriform from the Early Triassic
File:Staurikosaurus BW.jpg|''[[Staurikosaurus]],'' one of the earliest dinosaurs, a member of the Triassic family [[Herrerasauridae]]
File:Postosuchus kirkpatricki.jpg|''[[Postosuchus]],'' a [[Rauisuchidae|rauisuchid]] which was an [[apex predator]] in parts of Late Triassic North America
File:Sellosaurus.jpg|''[[Plateosaurus]]'' was one of the largest of early [[sauropodomorph]]s, or "prosauropods", of the Late Triassic
File:Coelophysis size flipped.jpg|''[[Coelophysis]]'' was one of the most abundant theropod dinosaurs in the Late Triassic
</gallery>

==== Marine reptiles ====
[[File:Triassic marine vertebrate apex predators.png|thumb|upright=1.2|Marine vertebrate apex predators of the [[Early Triassic]] and [[Anisian]] (Middle Triassic)<ref>Scheyer et al. (2014): Early Triassic Marine Biotic Recovery: The Predators' Perspective. PLoS ONE  https://doi.org/10.1371/journal.pone.0088987</ref>]]
There were many types of marine reptiles. These included the [[Sauropterygia]], which featured [[pachypleurosaur]]s and [[nothosaur]]s (both common during the Middle Triassic, especially in the [[Tethys Ocean|Tethys]] region), [[placodont]]s, the earliest known herbivorous marine reptile ''[[Atopodentatus]]'', and the first [[plesiosaur]]s. The first of the lizard-like [[Thalattosauria]] (''[[Askeptosaurus]]'') and the highly successful [[Ichthyopterygia|ichthyopterygian]]s, which appeared in [[Early Triassic]] seas, soon diversified. By the Middle Triassic, some ichthyopterygians were achieving very large body masses.<ref>{{Cite journal |last1=Zakharov |first1=Y. D. |last2=Nakajima |first2=Y. |last3=Arkhangelsky |first3=M. S. |last4=Popov |first4=A. M. |last5=Bondarenko |first5=L. G. |last6=Smyshlyaeva |first6=O. P. |last7=Pokrovsky |first7=V. K. |date=15 May 2024 |title=New Finds of Triassic Marine Reptiles from Eastern Russia: Ammonoid Age Control and Possible Evidence for Ichthyopterygian Affinities |url=https://link.springer.com/10.1134/S0869593824030080 |journal=[[Stratigraphy and Geological Correlation]] |language=en |volume=32 |issue=3 |pages=242–264 |doi=10.1134/S0869593824030080 |bibcode=2024SGC....32..242Z |issn=0869-5938 |access-date=13 August 2024 |via=Springer Link|url-access=subscription }}</ref>

==== Other reptiles ====
Among other reptiles, the earliest [[turtle]]s, like ''[[Proganochelys]]'' and ''[[Proterochersis]]'', appeared during the [[Norian]] Age (Stage) of the Late Triassic Period. The [[Lepidosauromorpha]], specifically the [[Sphenodontia]], are first found in the fossil record of the earlier Carnian Age, though the earliest lepidosauromorphs likely occurred in the Permian. The [[Procolophonidae]], the last surviving [[Parareptilia|parareptiles]], were an important group of small lizard-like herbivores. The [[drepanosaur]]s were a clade of unusual, chameleon-like arboreal reptiles with birdlike heads and specialised claws.

=== Synapsids ===
Three [[therapsid]] groups survived into the Triassic: [[dicynodont]]s, [[therocephalia]]ns, and [[cynodont]]s. The cynodont ''[[Cynognathus]]'' was a characteristic top predator in the [[Olenekian]] and [[Anisian]] of [[Gondwana]]. Both [[Kannemeyeriiformes|kannemeyeriiform]] dicynodonts and [[Gomphodontia|gomphodont]] cynodonts remained important [[herbivore]]s during much of the period. Therocephalians included both large predators (''[[Moschorhinus]]'') and herbivorous forms ([[Bauriidae|bauriids]]) until their extinction midway through the period. [[Ecteniniidae|Ecteniniid]] cynodonts played a role as large-sized, cursorial predators in the Late Triassic. During the [[Carnian]] (early part of the Late Triassic), some advanced cynodonts gave rise to the [[Evolution of mammals#From cynodonts to crown mammals|first mammals]].

During the Triassic, archosaurs displaced therapsids as the largest and most ecologically prolific terrestrial amniotes. This "Triassic Takeover" may have contributed to the [[evolution of mammals]] by forcing the surviving therapsids and their [[Mammaliaformes|mammaliaform]] successors to live as small, mainly nocturnal [[insectivore]]s. [[Nocturnal bottleneck|Nocturnal life]] may have forced the mammaliaforms to develop fur and a higher [[Basal metabolic rate|metabolic rate]].<ref name="RubenJones2000FurAndFeathers">{{cite journal |last1=Ruben |first1=J. A. |last2=Jones |first2=T. D. |name-list-style=amp |date=1 August 2000 |title=Selective Factors Associated with the Origin of Fur and Feathers |url=https://www.researchgate.net/publication/247478113 |journal=[[Integrative and Comparative Biology]] |volume=40 |issue=4 |pages=585–96 |doi=10.1093/icb/40.4.585 |access-date=24 November 2023 |doi-access=free}}</ref>

<gallery class="center">
File:Lystrosaurus BW.jpg|''[[Lystrosaurus]]'' was a widespread dicynodont and the most common land vertebrate during the Early Triassic, after animal life had been greatly diminished
File:Cynognathus BW.jpg|''[[Cynognathus]]'' was a carnivorous [[Mammaliaformes|mammal-like]] [[cynodont]] from the Early Triassic.
</gallery>


==Lagerstätten==
Two [[Early Triassic]] [[lagerstätten]] (high-quality fossil beds), the [[Dienerian]] aged [[Guiyang biota]]<ref>{{cite journal |last1=Dai |first1=Xu |last2=Davies |first2=Joshua H.F.L. |last3=Yuan |first3=Zhiwei |last4=Brayard |first4=Arnaud |last5=Ovtcharova |first5=Maria |last6=Xu |first6=Guanghui |last7=Liu |first7=Xiaokang |last8=Smith |first8=Christopher P.A. |last9=Schweitzer |first9=Carrie E. |last10=Li |first10=Mingtao |last11=Perrot |first11=Morgann G. |last12=Jiang |first12=Shouyi |last13=Miao |first13=Luyi |last14=Cao |first14=Yiran |last15=Yan |first15=Jia |last16=Bai |first16=Ruoyu |last17=Wang |first17=Fengyu |last18=Guo |first18=Wei |last19=Song |first19=Huyue |last20=Tian |first20=Li |last21=Dal Corso |first21=Jacopo |last22=Liu |first22=Yuting |last23=Chu |first23=Daoliang |last24=Song |first24=Haijun |year=2023 |title=A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem |journal=Science |volume=379 |issue=6632 |pages=567–572 |doi=10.1126/science.adf1622|pmid=36758082 |bibcode=2023Sci...379..567D |s2cid=256697946 |url=https://u-bourgogne.hal.science/hal-04016004 }}</ref> and the earliest [[Spathian]] aged [[Paris biota]]<ref>{{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 |last16=Stephen |first16=Daniel A. |last17=Thomazo |first17=Christophe |last18=Escarguel |first18=Gilles |title=Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna |journal=Science Advances |year=2017 |volume=3 |issue=2 |article-number=e1602159 |doi=10.1126/sciadv.1602159 |pmid=28246643 |pmc=5310825 |bibcode=2017SciA....3E2159B |doi-access=free }}</ref> stand out due to their exceptional preservation and [[biodiversity|diversity]]. They represent the earliest lagerstätten of the Mesozoic era and provide insight into the biotic recovery from the [[Permian-Triassic mass extinction]] event.

The [[Monte San Giorgio]] lagerstätte, now in the [[Lake Lugano]] region of northern [[Italy]] and southern [[Switzerland]], was in [[Middle Triassic]] times a [[lagoon]] behind reefs with an [[anoxic waters|anoxic]] bottom layer, so there were no scavengers and little turbulence to disturb fossilization, a situation that can be compared to the better-known Jurassic [[Solnhofen Limestone]] [[lagerstätte]]. The remains of fish and various marine reptiles (including the common [[pachypleurosaur]] ''[[Neusticosaurus]]'', and the bizarre long-necked [[archosauromorph]] ''[[Tanystropheus]]''), along with some terrestrial forms like ''[[Ticinosuchus]]'' and ''[[Macrocnemus]]'', have been recovered from this locality. All these fossils date from the [[Anisian]] and [[Ladinian]] [[age (geology)|ages]] (about 242 [[megaannum|Ma]] ago).

==Triassic–Jurassic extinction event==
{{Main|Triassic–Jurassic extinction event}}
[[File:Extinction Intensity.svg|thumb|upright=1.2|The mass extinction event is marked by 'End Tr']]
The Triassic Period ended with a mass extinction, which was particularly severe in the oceans; the [[conodont]]s disappeared, as did all the marine reptiles except [[Ichthyosauria|ichthyosaur]]s and [[plesiosaur]]s. Invertebrates like [[brachiopod]]s and [[mollusc]]s (such as [[gastropod]]s) were severely affected. In the oceans, 22% of marine families and possibly about half of marine genera went missing.

Though the end-Triassic extinction event was not equally devastating in all terrestrial ecosystems, several important clades of [[Crurotarsi|crurotarsans]] (large archosaurian reptiles previously grouped together as the [[Thecodontia|thecodont]]s) disappeared, as did most of the large labyrinthodont amphibians, groups of small reptiles, and most synapsids. Some of the early, primitive dinosaurs also became extinct, but more adaptive ones survived to evolve into the Jurassic. Surviving plants that went on to dominate the Mesozoic world included modern conifers and cycadeoids.

The cause of the Late Triassic extinction is uncertain. It was accompanied by huge [[volcano|volcanic]] eruptions that occurred as the supercontinent Pangaea began to break apart about 202 to 191 million years ago (40Ar/39Ar dates),<ref>Nomade et al., 2007 Palaeogeography, Palaeoclimatology, Palaeoecology 244, 326–44.</ref> forming the [[Central Atlantic Magmatic Province]] (CAMP),<ref>Marzoli et al., 1999, Science 284. Extensive 200-million-year-old continental flood basalts of the Central Atlantic Magmatic Province, pp. 618–620.</ref> one of the largest known inland volcanic events since the planet had first cooled and stabilized. Other possible but less likely causes for the extinction events include global cooling or even a [[bolide]] impact, for which an impact crater containing [[Manicouagan Reservoir]] in [[Quebec]], [[Canada]], has been singled out. However, the Manicouagan impact melt has been dated to 214±1 Mya. The date of the Triassic-Jurassic boundary has also been more accurately fixed recently, at {{Period start|Jurassic}} Mya. Both dates are gaining accuracy by using more accurate forms of radiometric dating, in particular the decay of uranium to lead in zircons formed at time of the impact. So, the evidence suggests the Manicouagan impact preceded the end of the Triassic by approximately 10±2 Ma. It could not therefore be the immediate cause of the observed mass extinction.<ref>Hodych & Dunning, 1992.</ref>
[[File:Petrified Forest National Park-Rainbow Forest Museum-1.jpg|thumb|Skull of a Triassic Period phytosaur found in the Petrified Forest National Park]]
The number of Late Triassic extinctions is disputed. Some studies suggest that there are at least two periods of extinction towards the end of the Triassic, separated by 12 to 17 million years. But arguing against this is a recent study of North American faunas. In the [[Petrified Forest National Park|Petrified Forest]] of northeast Arizona there is a unique sequence of late Carnian-early Norian terrestrial sediments. An analysis in 2002 found no significant change in the paleoenvironment.<ref>{{cite web |url=http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_42936.htm |title=No Significant Nonmarine Carnian-Norian (Late Triassic) Extinction Event: Evidence From Petrified Forest National Park |website=gsa.confex.com |access-date=2003-12-12 |archive-url=https://web.archive.org/web/20031106231251/http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_42936.htm |archive-date=2003-11-06}}</ref> [[Phytosaur]]s, the most common fossils there, experienced a change-over only at the genus level, and the number of species remained the same. Some [[aetosaur]]s, the next most common tetrapods, and early dinosaurs, passed through unchanged. However, both phytosaurs and aetosaurs were among the groups of archosaur reptiles completely wiped out by the end-Triassic extinction event.

It seems likely then that there was some sort of end-Carnian extinction, when several herbivorous archosauromorph groups died out, while the large herbivorous [[therapsid]]s—the [[Kannemeyeriidae|kannemeyeriid]] dicynodonts and the [[Traversodontidae|traversodont]] cynodonts—were much reduced in the northern half of Pangaea ([[Laurasia]]).

These extinctions within the Triassic and at its end allowed the dinosaurs to expand into many niches that had become unoccupied. Dinosaurs became increasingly dominant, abundant and diverse, and remained that way for the next 150 million years. The true "Age of Dinosaurs" is during the following Jurassic and Cretaceous periods, rather than the Triassic.

==See also==
{{Portal|Geology|Paleontology}}
*{{annotated link|Geologic time scale}}
*{{annotated link|List of fossil sites}} ''(with link directory)''
* {{annotated link|Triassic land vertebrate faunachrons}}
*{{annotated link|Phylloceratina}}
*{{annotated link|Dinosaur}}s
{{-}}

==Notes==
{{Reflist|26em}}

==References==
*[[Cesare Emiliani|Emiliani, Cesare]]. (1992). ''Planet Earth: Cosmology, Geology, & the Evolution of Life & the Environment''. Cambridge University Press. (Paperback Edition {{ISBN|0-521-40949-7}})
*Ogg, Jim; June, 2004, ''Overview of Global Boundary Stratotype Sections and Points (GSSP's)'' [http://www.stratigraphy.org/bak/gssp.htm Stratigraphy.org], Accessed April 30, 2006
*Stanley, Steven M. ''Earth System History.'' New York: W.H. Freeman and Company, 1999. {{ISBN|0-7167-2882-6}}
*Sues, Hans-Dieter & Fraser, Nicholas C. ''Triassic Life on Land: The Great Transition'' New York: Columbia University Press, 2010. Series: Critical Moments and Perspectives in Earth History and Paleobiology. {{ISBN|978-0-231-13522-1}}
*van Andel, Tjeerd, (1985) 1994, ''New Views on an Old Planet: A History of Global Change'', [[Cambridge University Press]]

==External links==
{{Commons category|Triassic}}
{{wiktionary}}
{{EB1911 Poster|Triassic System}}
*[https://web.archive.org/web/20151210044546/http://palaeos.com/mesozoic/triassic/triassic.htm Overall introduction]
*[https://web.archive.org/web/20160222224358/http://rainbow.ldgo.columbia.edu/courses/v1001/9.html 'The Triassic world']
*[http://gallery.in-tch.com/~earthhistory/triassic%20page%201.html Douglas Henderson's illustrations of Triassic animals]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}
*[https://web.archive.org/web/20170801065542/http://palaeo.gly.bris.ac.uk/palaeofiles/triassic/triextict.htm Paleofiles page on the Triassic extinctions]
*[http://www.geo-lieven.com/erdzeitalter/trias/trias.htm Examples of Triassic Fossils]
*[https://web.archive.org/web/20200809123734/https://ghkclass.com/ghkC.html?triassic Triassic (chronostratigraphy scale)]

{{Triassic Footer}}
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[[Category:Triassic| ]]
[[Category:Geological periods]]
[[Category:1834 in paleontology]]