# Triassic
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> Markdown URL: https://mediated.wiki/source/Triassic.md
> Source: https://en.wikipedia.org/wiki/Triassic
> Source revision: 1356288950
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{{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 225 million years ago during the [Norian](/source/Norian) age of the [Late Triassic](/source/Late_Triassic) epoch
| image_outcrop =
| caption_outcrop =
| image_art =
| caption_art =
| timeline = Triassic
| name_formality = Formal
| name_accept_date =
| alternate_spellings =
| synonym1 =
| synonym1_coined =
| synonym2 =
| synonym2_coined =
| synonym3 =
| synonym3_coined =
| nicknames =
| former_names =
| proposed_names =
| celestial_body = earth
| usage = Global ([ICS](/source/International_Commission_on_Stratigraphy))
| timescales_used = ICS Time Scale
| formerly_used_by =
| not_used_by =
| chrono_unit = Period
| strat_unit = System
| proposed_by =
| timespan_formality = Formal
| lower_boundary_def = First appearance of the [conodont](/source/conodont) ''[Hindeodus parvus](/source/Hindeodus)''
| lower_gssp_location = [Meishan](/source/Meishan), [Zhejiang](/source/Zhejiang), [China](/source/China)
| lower_gssp_coords = {{Coord|31.0798|N|119.7058|E|display=inline}}
| lower_gssp_accept_date = 2001[{{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 |doi-access=free }}]
| upper_boundary_def = First appearance of the [ammonite](/source/ammonite) ''[Psiloceras spelae tirolicum](/source/Psiloceras)''
| upper_gssp_location = Kuhjoch section, [Karwendel mountains](/source/Karwendel), [Northern Calcareous Alps](/source/Northern_Calcareous_Alps), Austria
| upper_gssp_coords = {{Coord|47.4839|N|11.5306|E|display=inline}}
| upper_gssp_accept_date = 2010[{{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 }}]
| sea_level =
}}
The '''Triassic''' ({{IPAc-en|t|r|aɪ|ˈ|æ|s|ɪ|k}}; sometimes symbolized as '''🝈''') is a [geologic period](/source/geologic_period) and a [stratigraphic system](/source/system_(stratigraphy)) that spans 50.5 million years from the end of the [Permian](/source/Permian) Period 251.902 Ma (million years ago) to the beginning of the [Jurassic](/source/Jurassic) Period 201.4 Ma.[{{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}}][{{dictionary.com|Triassic}}] The Triassic Period is the first and shortest geologic period of the [Mesozoic Era](/source/Mesozoic), and the seventh period of the [Phanerozoic Eon](/source/Phanerozoic). The start and the end of the Triassic Period featured major [extinction event](/source/extinction_event)s.[{{cite journal |last1=Sahney |first1=Sarda |last2=Benton |first2=Michael J |title=Recovery from the most profound mass extinction of all time |journal=Proceedings of the Royal Society B: Biological Sciences |date=7 April 2008 |volume=275 |issue=1636 |pages=759–765 |doi=10.1098/rspb.2007.1370 |pmid=18198148 |pmc=2596898 }}]
Chronologically, the Triassic Period is divided into three epochs: (i) the [Early Triassic](/source/Early_Triassic), (ii) the [Middle Triassic](/source/Middle_Triassic), and (iii) the [Late Triassic](/source/Late_Triassic). The Triassic Period began after the [Permian–Triassic extinction event](/source/Permian%E2%80%93Triassic_extinction_event) that much reduced the [biosphere](/source/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](/source/Mesozoic) Era. [Reptiles](/source/Reptiles), especially [archosaur](/source/archosaur)s, were the chief terrestrial vertebrates during this time. A specialized group of archosaurs, called [dinosaur](/source/dinosaur)s, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period.[{{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](/source/Science_(journal)) |volume=321 |issue=5895 |pages=1485–1488 |date=12 September 2008 |doi=10.1126/science.1161833 |bibcode=2008Sci...321.1485B |pmid=18787166 |hdl=20.500.11820/00556baf-6575-44d9-af39-bdd0b072ad2b |hdl-access=free }}] Archosaurs that became dominant in this period were primarily [pseudosuchia](/source/pseudosuchia)ns, relatives and ancestors of modern [crocodilians](/source/crocodilians), while some archosaurs specialized in flight, the first time among vertebrates, becoming the [pterosaurs](/source/pterosaurs). [Therapsids](/source/Therapsids), the dominant vertebrates of the preceding Permian period, saw a brief surge in diversification in the Triassic, with [dicynodonts](/source/Dicynodontia) and [cynodonts](/source/Cynodontia) quickly becoming dominant, but they declined throughout the period with the majority becoming extinct by the end. However, the first stem-group [mammal](/source/mammal)s ([mammaliamorphs](/source/Mammaliamorpha)), themselves a specialized subgroup of cynodonts, appeared during the Triassic and would survive the extinction event, allowing them to radiate during the Jurassic. [Amphibian](/source/Amphibian)s were primarily represented by the [temnospondyls](/source/Temnospondyli), 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](/source/lissamphibia)ns (including stem-group [frog](/source/frog)s, [salamander](/source/salamander)s and [caecilian](/source/caecilian)s) also became more common during the Triassic and survived the extinction event. The earliest known [neopterygian](/source/Neopterygii) fish, including early [holosteans](/source/Holostei) and [teleost](/source/teleost)s, 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](/source/supercontinent) of [Pangaea](/source/Pangaea) dominated the globe during the Triassic, but in the latest Triassic ([Rhaetian](/source/Rhaetian)) and Early Jurassic it began to gradually rift into two separate landmasses: [Laurasia](/source/Laurasia) to the north and [Gondwana](/source/Gondwana) to the south. The global climate during the Triassic was mostly hot and dry,[{{cite news |last1=Dell'Amore |first1=Christine |title='Lethally Hot' Earth Was Devoid of Life—Could It Happen Again? |url=https://www.nationalgeographic.com/history/article/121018-triassic-extinctions-hot-global-warming-science-environment |work=National Geographic |date=19 October 2012 }}] 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](/source/Triassic%E2%80%93Jurassic_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 Alberti](/source/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](/source/Germany): the lower [Buntsandstein](/source/Buntsandstein) (colourful [sandstone](/source/sandstone)'')'', the middle [Muschelkalk](/source/Muschelkalk) (shell-bearing [limestone](/source/limestone)) and the upper [Keuper](/source/Keuper) (coloured [clay](/source/clay)).[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 page 324] :]
"… 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."
( … 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".)
File:Stadtroda Sandstein.jpg|[Early Triassic](/source/Early_Triassic) sandstone (Buntsandstein) near [Stadtroda](/source/Stadtroda), Germany
File:Obere Schaumkalkbank am Altenberg bei Dörzbach 280308.jpg|[Middle Triassic](/source/Middle_Triassic) Muschelkalk (shell-bearing limestone) near [Dörzbach](/source/D%C3%B6rzbach), Germany
File:Kirnbergaufschluss.JPG|[Late Triassic](/source/Late_Triassic) [Steigerwald Formation](/source/Steigerwald_Formation) and overlying [Hassberge Formation](/source/Hassberge_Formation) in [Schönbuch](/source/Sch%C3%B6nbuch), Germany
==Dating and subdivisions==
On the [geologic time scale](/source/geologic_time_scale), the Triassic is usually divided into [Early](/source/Early_Triassic), [Middle](/source/Middle_Triassic), and [Late Triassic](/source/Late_Triassic) [Epoch](/source/epoch_(geology))s, and the corresponding rocks are referred to as Lower, Middle, or Upper Triassic. The [faunal stages](/source/faunal_stages) from the youngest to oldest are:
{|class="wikitable"
! span=col| Series/epoch
! span=col| Stage/age
! span=col| Lower boundary
|-
| style="background-color: {{period color|Early Jurassic}}; |Lower/Early Jurassic
| style="background-color: {{period color|Hettangian}}; color:white;" |Hettangian
|{{period start|Hettangian}} {{period start error|Hettangian}} Ma
|-
| rowspan="3", style="background-color: {{period color|Late Triassic}};" | {{Colored period link|Late Triassic|Upper/Late Triassic}}
|style="background-color: {{period color|Rhaetian}};" | {{Colored period link|Rhaetian}}
|{{period start|Rhaetian}} {{period start error|Rhaetian}} Ma
|-
|style="background-color: {{period color|Norian}};" | {{Colored period link|Norian}}
|{{period start|Norian}} {{period start error|Norian}} Ma
|-
|style="background-color: {{period color|Carnian}};" | {{Colored period link|Carnian}}
|{{period start|Carnian}} {{period start error|Carnian}} Ma
|-
| rowspan="2", style="background-color: {{period color|Middle Triassic}}" | {{Colored period link|Middle Triassic|Middle Triassic}}
|style="background-color: {{period color|Ladinian}};" | {{Colored period link|Ladinian}}
|{{period start|Ladinian}} {{period start error|Ladinian}} Ma
|-
|style="background-color: {{period color|Anisian}};" | {{Colored period link|Anisian}}
|{{period start|Anisian}} {{period start error|Anisian}} Ma
|-
| rowspan="2", style="background-color: {{period color|Early Triassic}};" | {{Colored period link|Early Triassic|Lower/Early Triassic}}
|style="background-color: {{period color|Olenekian}};" | {{Colored period link|Olenekian}}
|{{period start|Olenekian}} {{period start error|Olenekian}} Ma
|-
|style="background-color: {{period color|Induan}};" | {{Colored period link|Induan}}
|{{period start|Induan}} {{period start error|Induan}} Ma
|}
==Paleogeography==
thumb|upright=1.5|350px|View of the Tethys area during the Ladinian stage (230 Ma)
thumb|350px|230 Ma continental reconstructionAt 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 [Laurussia](/source/Laurasia) in the north and Gondwana in the south. The [Paleo](/source/Tethys_Ocean)- and [Neo-Tethys](/source/Tethys_Ocean) oceans lay within the arc of the supercontinent with the vast [Panthalassa](/source/Panthalassa) Ocean beyond.[{{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}}{{page needed|date=March 2026}}] [North China](/source/North_China_Craton) and [Amuria](/source/Amur_plate), and [South China](/source/South_China_Craton) were separated from Pangea by the Paleoasian Ocean, but this closed by the Late Triassic.[{{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 |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 |journal=Earth-Science Reviews |date=June 2024 |volume=253 |article-number=104771 |doi=10.1016/j.earscirev.2024.104771 |bibcode=2024ESRv..25304771S }}]
Pangea was surrounded by [subduction zones](/source/Subduction) 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](/source/Atlantic_Ocean), [Indian](/source/Indian_Ocean) and [Southern](/source/Southern_Ocean) oceans.[{{cite book |last1=Scotese |first1=C.R. |last2=Schettino |first2=A. |title=Permo-Triassic Salt Provinces of Europe, North Africa and the Atlantic Margins |chapter=Late Permian-Early Jurassic Paleogeography of Western Tethys and the World |date=2017 |pages=57–95 |doi=10.1016/B978-0-12-809417-4.00004-5 |isbn=978-0-12-809417-4 }}]
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.[{{cite journal |last1=Riel |first1=Nicolas |last2=Jaillard |first2=Etienne |last3=Martelat |first3=Jean-Emmanuel |last4=Guillot |first4=Stéphane |last5=Braun |first5=Jean |title=Permian-Triassic Tethyan realm reorganization: Implications for the outward Pangea margin |journal=Journal of South American Earth Sciences |date=January 2018 |volume=81 |pages=78–86 |doi=10.1016/j.jsames.2017.11.007 |bibcode=2018JSAES..81...78R }}]
The narrow [Cimmerian](/source/Cimmeria_(continent)) [terrane](/source/terrane)s 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.[{{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. |title=A review of Pangaea dispersal and Large Igneous Provinces – In search of a causative mechanism |journal=Earth-Science Reviews |date=July 2020 |volume=206 |article-number=102902 |doi=10.1016/j.earscirev.2019.102902 |bibcode=2020ESRv..20602902P }}]
=== 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](/source/Triassic_Boreal_Ocean_Delta_Plain))[{{cite journal |last1=Klausen |first1=Tore Grane |last2=Nyberg |first2=Björn |last3=Helland-Hansen |first3=William |title=The largest delta plain in Earth's history |journal=Geology |date=May 2019 |volume=47 |issue=5 |pages=470–474 |doi=10.1130/G45507.1 |bibcode=2019Geo....47..470K |doi-access=free }}] advanced across the shallow [Arctic Ocean](/source/Arctic_Ocean). Their [catchment areas](/source/Drainage_basin) the high ground of the [Urals](/source/Ural_Mountains), [Fennoscandinavia](/source/Fennoscandia), the Canada-Greenland Shield and the Lomonosov High.[{{cite journal |last1=Hadlari |first1=Thomas |last2=Midwinter |first2=Derrick |last3=Poulton |first3=Terry P. |last4=Matthews |first4=William A. |title=A Pangean rim of fire: Reviewing the Triassic of western Laurentia |journal=Lithosphere |date=13 April 2017 |article-number=L643.1 |doi=10.1130/L643.1 |doi-access=free }}] 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](/source/Slide_Mountain_Ocean) and the [Sonoma orogeny](/source/Sonoma_orogeny).[{{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 |journal=Tectonics |volume=34 |issue=5 |pages=1009–1029 |doi=10.1002/2014TC003760 |bibcode=2015Tecto..34.1009F }}]
The opening of the Neo-Tethys created [passive margin](/source/passive_margin)s along the Arabian and Indian margins.[{{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 |journal=Journal of Petroleum Geology |volume=47 |issue=2 |pages=123–171 |doi=10.1111/jpg.12854 |bibcode=2024JPetG..47..123M }}] Rifting in the Neo-Tethys extended westwards between the [Pontides](/source/Pontic_Mountains) and [Taurides](/source/Taurus_Mountains) terranes of Turkey during the Late Triassic.[{{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 |title=Late Triassic sedimentary records in the northern Tethyan Himalaya: Tectonic link with Greater India |journal=Geoscience Frontiers |date=January 2018 |volume=9 |issue=1 |pages=273–291 |doi=10.1016/j.gsf.2017.04.001 |bibcode=2018GeoFr...9..273C |doi-access=free }}]
The counterclockwise rotation of Pangea precipitated [dextral](/source/Fault_(geology)) [transpression](/source/transpression) across the NNE-SSW trending, west-dipping subduction zone, along the eastern Australian margin, which culminated in the [Hunter-Bowen orogeny](/source/Hunter%E2%80%93Bowen_orogeny) (c. 260-230 Ma).[{{cite journal |last1=Rosenbaum |first1=Gideon |title=The Tasmanides: Phanerozoic Tectonic Evolution of Eastern Australia |journal=Annual Review of Earth and Planetary Sciences |date=30 May 2018 |volume=46 |issue=1 |pages=291–325 |doi=10.1146/annurev-earth-082517-010146 |bibcode=2018AREPS..46..291R }}] Following this, the magmatic arc rotated to north-south and compression gave way to extension. This was accompanied by [subduction rollback](/source/Subduction) and back-arc basin formation.[{{cite journal |last1=del Rey |first1=Álvaro |last2=Deckart |first2=Katja |last3=Planavsky |first3=Noah |last4=Arriagada |first4=César |last5=Martínez |first5=Fernando |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 |journal=Gondwana Research |date=December 2019 |volume=76 |pages=303–321 |doi=10.1016/j.gr.2019.05.007 |bibcode=2019GondR..76..303D }}][{{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 |title=On the nature of the Cimmerian Continent |journal=Earth-Science Reviews |date=December 2023 |volume=247 |article-number=104520 |doi=10.1016/j.earscirev.2023.104520 |bibcode=2023ESRv..24704520S |doi-access=free }}] The Eurasian sector of Pangea lay along its north and northwestern margin.[{{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 |title=Central China Orogenic Belt and amalgamation of East Asian continents |journal=Gondwana Research |date=December 2021 |volume=100 |pages=131–194 |doi=10.1016/j.gr.2021.03.006 |bibcode=2021GondR.100..131D }}]
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.[{{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 |title=Structural, stratigraphic and sedimentological characterisation of a wide rift system: The Triassic rift system of the Central Atlantic Domain |journal=Earth-Science Reviews |date=July 2016 |volume=158 |pages=89–124 |doi=10.1016/j.earscirev.2016.03.008 |bibcode=2016ESRv..158...89L |hdl=2164/8901 }}] The location of this rifting followed the pre-existing structures of the [Variscan orogeny](/source/Variscan_orogeny), and began immediately after the [orogenic collapse](/source/orogenic_collapse) of the Variscan belt.[{{cite book |last1=Marzoli |first1=Andrea |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 |last10=Jourdan |first10=Fred |title=The Late Triassic World |chapter=The Central Atlantic Magmatic Province (CAMP): A Review |series=Topics in Geobiology |date=2018 |volume=46 |pages=91–125 |doi=10.1007/978-3-319-68009-5_4 |isbn=978-3-319-68008-8 }}] Despite its size, the period of magmatism was brief, lasting only about 1 million years. Such intense igneous activity indicates widespread [mantle](/source/Mantle_(geology)) melting, rather than a simple [plume](/source/Mantle_plume) within the mantle. The varied [petrological](/source/Petrology) composition of the CAMP magmatism reflects local contamination of the upper mantle by continental lithosphere, including partial melting of previously subducted slabs.[{{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 |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 |date=12 November 2024 |volume=121 |issue=46 |article-number=e2415486121 |doi=10.1073/pnas.2415486121 |doi-access=free |pmc=11573653 |pmid=39467154|bibcode=2024PNAS..12115486K }}][{{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}}]]]
=== Paleooceanography ===
[Eustatic sea level](/source/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.[{{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](/source/Geological_Society_of_America) |volume=28 |issue=12 |pages=4–9 |doi=10.1130/GSATG381A.1 |bibcode=2018GSAT...28l...4H |doi-access=free }}] 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.[{{cite book |last1=Embry |first1=Ashton F. |title=Sea-Level Changes |chapter=Triassic Sea-Level Changes: Evidence from the Canadian Arctic Archipelago |date=1988 |pages=249–259 |doi=10.2110/pec.88.01.0249 |isbn=978-1-56576-089-9 }}] 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.[Stanley, 452–53.] The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial [monsoons](/source/monsoons),[{{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 |journal=[Gondwana Research](/source/Gondwana_Research) |volume=69 |pages=1–24 |doi=10.1016/j.gr.2018.11.015 |bibcode=2019GondR..69....1Z }}]
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.[{{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}}] 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](/source/Svalbard) Islands), the [North America](/source/North_America)n continent, the [South China block](/source/South_China_Craton) and [Argentina](/source/Argentina). The best-studied of such episodes of humid climate, and probably the most intense and widespread, was the [Carnian Pluvial Event](/source/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](/source/greenhouse_gas)es from the Siberian Traps. The Early Triassic began with the [Permian](/source/Permian)-Triassic Thermal Maximum (PTTM) and was followed by the brief [Dienerian](/source/Dienerian) Cooling (DC) from 251 to 249 Ma, which was in turn followed by the Latest [Smithian](/source/Olenekian) Thermal Maximum (LSTT) around 249 to 248 Ma. During the Latest [Olenekian](/source/Olenekian) Cooling (LOC), from 248 to 247 Ma, temperatures cooled by about 6 °C.[{{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=April 2021 |title=Phanerozoic paleotemperatures: The earth's changing climate during the last 540 million years |journal=[Earth-Science Reviews](/source/Earth-Science_Reviews) |volume=215 |article-number=103503 |doi=10.1016/j.earscirev.2021.103503 |bibcode=2021ESRv..21503503S }}]
=== 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.[{{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 |journal=[Earth and Planetary Science Letters](/source/Earth_and_Planetary_Science_Letters) |volume=415 |pages=165–174 |doi=10.1016/j.epsl.2015.01.038 |bibcode=2015E&PSL.415..165T }}] From 242 to 233 Ma, the Ladinian-Carnian Cooling (LCC) ensued.[{{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 |journal=[Earth and Planetary Science Letters](/source/Earth_and_Planetary_Science_Letters) |volume=578 |article-number=117321 |doi=10.1016/j.epsl.2021.117321 |bibcode=2022E&PSL.57817321D }}] The eruption of the Wrangellia Large Igneous Province around 234 Ma caused abrupt global warming, terminating the cooling trend of the LCC.[{{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. |title=Discovery of a major negative 13C spike in the Carnian (Late Triassic) linked to the eruption of Wrangellia flood basalts |journal=[Geology](/source/Geology_(journal)) |date=2012 |volume=40 |issue=1 |pages=79–82 |doi=10.1130/G32473.1 |bibcode=2012Geo....40...79D }}] This warming was responsible for the Carnian Pluvial Event and resulted in an episode of widespread global humidity.[{{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 |journal=[Review of Palaeobotany and Palynology](/source/Review_of_Palaeobotany_and_Palynology) |volume=304 |article-number=104704 |doi=10.1016/j.revpalbo.2022.104704 |bibcode=2022RPaPa.30404704L |hdl=10852/99190 |hdl-access=free }}] The CPE ushered in the Mid-Carnian Warm Interval (MCWI), which lasted from 234 to 227 Ma.[{{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=April 2014 |title=A Middle–Late Triassic (Ladinian–Rhaetian) carbon and oxygen isotope record from the Tethyan Ocean |journal=[Palaeogeography, Palaeoclimatology, Palaeoecology](/source/Palaeogeography%2C_Palaeoclimatology%2C_Palaeoecology) |volume=399 |pages=246–259 |doi=10.1016/j.palaeo.2014.01.018 |bibcode=2014PPP...399..246M }}] 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](/source/Manicouagan_Impact_Crater).[{{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](/source/Scientific_Reports) |volume=10 |issue=1 |page=11984 |doi=10.1038/s41598-020-68542-w |pmid=32704030 |pmc=7378230 |bibcode=2020NatSR..1011984I }}] The Rhaetian Cool Interval (RCI) lasted from 209 to 201 Ma.[{{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](/source/Nature_Communications) |volume=11 |issue=1 |page=1670 |doi=10.1038/s41467-020-15325-6 |pmc=7138847 |pmid=32265448 |bibcode=2020NatCo..11.1670C }}]
== Flora ==
[[File:Triassic plants MKL Bd. 15 1890 (128662915).jpg|thumb|upright|left|Triassic flora as depicted in {{Lang|de|[Meyers Konversations-Lexikon](/source/Meyers_Konversations-Lexikon)}} (1885–1890)]]
=== Land plants ===
During the Early Triassic, [lycophyte](/source/lycophyte)s, particularly those of the order [Isoetales](/source/Isoetales) (which contains living [quillwort](/source/quillwort)s), rose to prominence due to the environmental instability following the Permian-Triassic extinction, with one particularly notable example being the genus ''[Pleuromeia](/source/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.[{{cite journal |last1=Looy |first1=Cindy V. |last2=van Konijnenburg-van Cittert |first2=Johanna H. A. |last3=Duijnstee |first3=Ivo A. P. |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 |date=2 March 2021 |volume=9 |article-number=615370 |doi=10.3389/feart.2021.615370 |doi-access=free |bibcode=2021FrEaS...9...55L }}]
While having first appeared during the Permian, the extinct seed plant group [Bennettitales](/source/Bennettitales) first became a prominent element in global floras during the Late Triassic, a position they would hold for much of the Mesozoic.[{{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}}] In the Southern Hemisphere landmasses of Gondwana, the tree ''[Dicroidium](/source/Dicroidium)'', an extinct "[seed fern](/source/seed_fern)" belong to the order [Corystospermales](/source/Corystospermales) was a dominant element in forest habitats across the region during the Middle-Late Triassic.[{{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 }}] During the Late Triassic, the [Ginkgoales](/source/Ginkgoales) (which today are represented by only a single species, ''[Ginkgo biloba](/source/Ginkgo_biloba)'') underwent considerable diversification.[{{Cite journal |last=Zhou |first=Zhi-Yan |date=March 2009 |title=An overview of fossil Ginkgoales |journal=Palaeoworld |volume=18 |issue=1 |pages=1–22 |doi=10.1016/j.palwor.2009.01.001 }}] Conifers were abundant during the Triassic, and included the [Voltziales](/source/Voltziales) (which contains various lineages, probably including those ancestral to modern conifers),[{{cite journal |last1=Forte |first1=Giuseppa |last2=Kustatscher |first2=Evelyn |last3=Van Konijnenburg-van Cittert |first3=Johanna H. A. |title=Conifer Diversity in the Middle Triassic: New Data from the Fossillagerstätte Kühwiesenkopf/Monte Prà della Vacca (Pelsonian, Anisian) in the Dolomites (Northeastern Italy) |journal=International Journal of Plant Sciences |date=July 2021 |volume=182 |issue=6 |pages=445–467 |doi=10.1086/714280 |bibcode=2021IJPlS.182..445F }}] as well as the extinct family [Cheirolepidiaceae](/source/Cheirolepidiaceae), which first appeared in the Late Triassic, and would be prominent throughout most of the rest of the Mesozoic.[{{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 |journal=American Journal of Botany |volume=104 |issue=2 |pages=322–334 |doi=10.3732/ajb.1600321 |pmid=28213347 |hdl=11336/40738 |hdl-access=free }}]
==== Coal ====
[[File:Prospect Hill Monterey Pine Forest.jpg|thumb|upright=1.2|Immediately above the Permian–Triassic boundary the [glossopteris](/source/glossopteris) flora was suddenly largely displaced by an [Australia](/source/Australia)-wide coniferous flora[{{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]}}]]]
No known [coal](/source/coal) deposits date from the start of the Triassic Period. This is known as the [Early Triassic](/source/Early_Triassic) "coal gap" and can be seen as part of the [Permian–Triassic extinction event](/source/Permian%E2%80%93Triassic_extinction_event).[{{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}}] Possible explanations for the coal gap include sharp drops in sea level at the time of the Permo-Triassic boundary;[{{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 |journal=[Nature](/source/Nature_(journal)) |volume=337 |issue=6202 |pages=39 [42] |bibcode=1989Natur.337...39H |doi=10.1038/337039a0 }}] 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;[{{cite book |last1=Retallack |first1=Gregory J. |last2=Krull |first2=Evelyn S. |title=Wetlands through Time |chapter=Carbon isotopic evidence for terminal-Permian methane outbursts and their role in extinctions of animals, plants, coral reefs, and peat swamps |date=2006 |doi=10.1130/2006.2399(12) |isbn=978-0-8137-2399-0 }}]
=== Phytoplankton ===
Before the Permian extinction, [Archaeplastida](/source/Archaeplastida) (red and green algae) had been the major marine [phytoplankton](/source/phytoplankton)s since about 659–645 million years ago,[{{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}}] when they replaced marine planktonic [cyanobacteria](/source/cyanobacteria), which first appeared about 800 million years ago, as the dominant phytoplankton in the oceans.[{{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 }}] In the Triassic, [secondary endosymbiotic](/source/Symbiogenesis) algae became the most important plankton.[{{cite journal |last1=Brocks |first1=Jochen J. |last2=Jarrett |first2=Amber J. M. |last3=Sirantoine |first3=Eva |last4=Hallmann |first4=Christian |last5=Hoshino |first5=Yosuke |last6=Liyanage |first6=Tharika |title=The rise of algae in Cryogenian oceans and the emergence of animals |journal=Nature |date=August 2017 |volume=548 |issue=7669 |pages=578–581 |doi=10.1038/nature23457 |pmid=28813409 }}]
{{clear}}
== Fauna ==
[[File:Triassic Utah.JPG|thumb|upright=1.2|Middle Triassic marginal marine sequence, southwestern [Utah](/source/Utah)]]
=== Marine invertebrates ===
In [marine environments](/source/Ocean), new modern types of [coral](/source/coral)s appeared in the Early Triassic, forming small patches of [reefs](/source/reefs) of modest extent compared to the great reef systems of [Devonian](/source/Devonian) or modern times. At the end of the Carnian, a reef crisis occurred in South China.[{{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 |journal=[Journal of Asian Earth Sciences](/source/Journal_of_Asian_Earth_Sciences) |volume=164 |pages=104–124 |doi=10.1016/j.jseaes.2018.06.021 |bibcode=2018JAESc.164..104J }}] [Serpulids](/source/Serpulidae) appeared in the Middle Triassic.[{{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 |doi=10.3176/earth.2009.4.07 |doi-access=free |bibcode=2009EsJES..58..286V }}] [Microconchids](/source/Microconchids) were abundant. The shelled [cephalopod](/source/cephalopod)s called [ammonite](/source/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.[{{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 |journal=[Palaeogeography, Palaeoclimatology, Palaeoecology](/source/Palaeogeography%2C_Palaeoclimatology%2C_Palaeoecology) |volume=208 |issue=3–4 |pages=227–223 |doi=10.1016/j.palaeo.2004.03.005 |bibcode=2004PPP...208..207K }}]
=== Insects ===
Aquatic insects rapidly diversified during the Middle Triassic, with this time interval representing a crucial diversification for [Holometabola](/source/Holometabola), the clade containing the majority of modern insect species.[{{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](/source/Science_Advances) |volume=4 |issue=9 |article-number=eaat1380 |doi=10.1126/sciadv.aat1380 |pmc=6124916 |pmid=30191177 |bibcode=2018SciA....4.1380Z }}]
=== Fish ===
[[File:Birgeria recon.jpg|right|thumb|250px|''[Birgeria](/source/Birgeria)'']]
In the wake of the [Permian-Triassic mass extinction event](/source/end-Permian_mass_extinction), the [fish](/source/fish) fauna was remarkably uniform, with many [families](/source/Family_(taxonomy)) and [genera](/source/genera) exhibiting a [cosmopolitan distribution](/source/cosmopolitan_distribution).[{{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 |url=https://hal.science/hal-01253154 }}] [Coelacanth](/source/Coelacanth)s show their highest post-[Devonian](/source/Devonian) diversity in the [Early Triassic](/source/Early_Triassic).[{{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 }}] [Ray-finned fishes](/source/Actinopterygians) (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 [taphonomic megabias](/source/megabias).[{{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 }}] The first [stem-group](/source/stem-group) [teleost](/source/teleost)s appeared during the Triassic (teleosts are by far the most diverse group of fish today).[ Predatory actinopterygians such as [saurichthyids](/source/Saurichthys) and [birgeriids](/source/Birgeria), 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.][{{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}}] Lakes and rivers were populated by [lungfish](/source/lungfish) (Dipnoi), such as ''[Ceratodus](/source/Ceratodus_(genus))'', which are mainly known from the dental plates, abundant in the fossils record.[{{cite journal |last1=Agnolin |first1=Federico L. |last2=Mateus |first2=Octávio |last3=Milàn |first3=Jesper |last4=Marzola |first4=Marco |last5=Wings |first5=Oliver |last6=Adolfssen |first6=Jan Schulz |last7=Clemmensen |first7=Lars B. |title=Ceratodus tunuensis, sp. nov., a new lungfish (Sarcopterygii, Dipnoi) from the Upper Triassic of central East Greenland |journal=Journal of Vertebrate Paleontology |date=4 March 2018 |volume=38 |issue=2 |article-number=e1439834 |doi=10.1080/02724634.2018.1439834 }}] [Hybodonts](/source/Hybodonts), a group of shark-like [cartilaginous fish](/source/cartilaginous_fish), were dominant in both freshwater and marine environments throughout the Triassic.[{{cite journal |last1=Kumar |first1=Krishna |last2=Bajpai |first2=Sunil |last3=Pandey |first3=Pragya |last4=Ghosh |first4=Triparna |last5=Bhattacharya |first5=Debasish |title=Hybodont sharks from the Jurassic of Jaisalmer, western India |journal=Historical Biology |date=3 June 2022 |volume=34 |issue=6 |pages=953–963 |doi=10.1080/08912963.2021.1954920 }}] Last survivors of the mainly [Palaeozoic](/source/Palaeozoic) [Eugeneodontida](/source/Eugeneodontida) are known from the Early Triassic.[{{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 }}]
=== Amphibians ===
[[File:Mastodonsaurus3.jpg|thumb|170px|right|Reconstruction of the Triassic amphibian ''[Mastodonsaurus](/source/Mastodonsaurus)'']]
[Temnospondyl](/source/Temnospondyli) [amphibian](/source/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](/source/Tupilakosaurus)'', ''[Thabanchuia](/source/Thabanchuia)'', [Branchiosauridae](/source/Branchiosauridae) and ''[Micropholis](/source/Micropholis_(amphibian))'', all of which died out in Early Triassic, and the successful [Stereospondyli](/source/Stereospondyli), with survivors into the Cretaceous Period. The largest Triassic stereospondyls, such as ''[Mastodonsaurus](/source/Mastodonsaurus),'' were up to {{convert|4|to|6|m|ft}} in length.[{{cite book |last1=Wells |first1=Kentwood D. |title=The Ecology and Behavior of Amphibians |date=2010 |publisher=University of Chicago Press |isbn=978-0-226-89333-4 |page=8 |url={{GBurl|eDKEKy5JJbIC|p=8}} }}][{{cite book |last1=Benton |first1=Michael J. |chapter=Temnospondyls and Reptiliomorphs after the Carboniferous |pages=97–99 |chapter-url={{GBurl|VThUUUtM8A4C|p=97}} |title=Vertebrate Palaeontology |date=2009 |publisher=John Wiley & Sons |isbn=978-1-4051-4449-0 }}] Some lineages (e.g. [trematosaur](/source/trematosaur)s) flourished briefly in the Early Triassic, while others (e.g. [capitosaur](/source/capitosaur)s) remained successful throughout the whole period, or only came to prominence in the Late Triassic (e.g. ''[Plagiosaurus](/source/Plagiosaurus)'', [metoposaur](/source/metoposaur)s).
The first [Lissamphibia](/source/Lissamphibia)ns (modern amphibians) appear in the Triassic, with the progenitors of the first [frog](/source/frog)s already present by the Early Triassic. However, the group as a whole did not become common until the [Jurassic](/source/Jurassic), when the temnospondyls had become very rare.
Most of the [Reptiliomorpha](/source/Reptiliomorpha), stem-amniotes that gave rise to the amniotes, disappeared in the Triassic, but two water-dwelling groups survived: [Embolomeri](/source/Embolomeri) that only survived into the early part of the period, and the [Chroniosuchia](/source/Chroniosuchia), which survived until the end of the Triassic.
The [Ashfield Shale](/source/Ashfield_Shale) of western [Sydney](/source/Sydney), formed during the Middle Triassic, features amphibian fossils from that period.[{{cite journal |last1=Farman |first1=Roy M. |last2=Bell |first2=Phil R. |title=Australia's earliest tetrapod swimming traces from the Hawkesbury Sandstone (Middle Triassic) of the Sydney Basin |journal=Journal of Paleontology |date=September 2020 |volume=94 |issue=5 |pages=966–978 |doi=10.1017/jpa.2020.22 }}]
=== Reptiles ===
==== Archosauromorphs ====
The Permian–Triassic extinction devastated terrestrial life. Biodiversity rebounded as the [surviving species](/source/pioneer_organisms) repopulated empty terrain, but these were short-lived. Diverse communities with complex [food-web](/source/food-web) structures took 30 million years to reestablish.[{{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}}] [Archosauromorph](/source/Archosauromorpha) reptiles, which had already appeared and diversified to an extent in the Permian Period, exploded in diversity as an [adaptive radiation](/source/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 [protorosaurs](/source/Protorosauria), which is likely a paraphyletic group rather than a true clade. [Tanystropheids](/source/Tanystropheidae) were a family of protorosaurs which elevated their neck size to extremes, with the largest genus ''[Tanystropheus](/source/Tanystropheus)'' having a neck longer than its body. The protorosaur family [Sharovipterygidae](/source/Sharovipterygidae) used their elongated hindlimbs for gliding. Other archosauromorphs, such as [rhynchosaur](/source/rhynchosaur)s and [allokotosaurs](/source/Allokotosauria), 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](/source/Trilophosaurus)'' (a common Late Triassic reptile with three-crowned teeth), ''[Teraterpeton](/source/Teraterpeton)'' (which had a long beak-like snout), and ''[Shringasaurus](/source/Shringasaurus)'' (a horned herbivore which reached a body length of {{convert|3–4|m}}).
One group of archosauromorphs, the [archosauriforms](/source/Archosauriformes), 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 [erythrosuchids](/source/Erythrosuchidae) were among the dominant carnivores in the early Triassic. [Phytosaurs](/source/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](/source/archosaur)s appeared in the early Triassic, splitting into two branches: [Avemetatarsalia](/source/Avemetatarsalia) (the ancestors to birds) and [Pseudosuchia](/source/Pseudosuchia) (the ancestors to crocodilians). Avemetatarsalians were a minor component of their ecosystems, but eventually produced the earliest [pterosaur](/source/pterosaur)s and [dinosaur](/source/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](/source/Coelophysis)'', which was {{convert|1|to|2|m|ft}} long. Triassic [sauropodomorphs](/source/Sauropodomorpha) primarily inhabited cooler regions of the world.[{{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](/source/Current_Biology) |volume=33 |issue=1 |pages=206–214 |doi=10.1016/j.cub.2022.11.064 |pmid=36528026 |doi-access=free |bibcode=2023CBio...33E.206D |hdl=1983/aea1ae86-2260-4d4d-a9d5-0fe38a0f470e |hdl-access=free }}]
The large predator ''[Smok](/source/Smok_(archosaur))'' 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](/source/aetosaur)s), large carnivores ("[rauisuchia](/source/rauisuchia)ns"), and the first [crocodylomorphs](/source/crocodylomorphs) ("[sphenosuchia](/source/sphenosuchia)ns"). [Aetosaurs](/source/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](/source/rauisuchia)ns" (formally known as [paracrocodylomorphs](/source/Paracrocodylomorpha)) 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.
File:Tanystropheus NT small.jpg|''[Tanystropheus](/source/Tanystropheus),'' a long-necked [tanystropheid](/source/Tanystropheidae)
File:Proterosuchus BW.jpg|''[Proterosuchus](/source/Proterosuchus)'', a crocodile-like early archosauriform from the Early Triassic
File:Staurikosaurus BW.jpg|''[Staurikosaurus](/source/Staurikosaurus),'' one of the earliest dinosaurs, a member of the Triassic family [Herrerasauridae](/source/Herrerasauridae)
File:Postosuchus kirkpatricki.jpg|''[Postosuchus](/source/Postosuchus),'' a [rauisuchid](/source/Rauisuchidae) which was an [apex predator](/source/apex_predator) in parts of Late Triassic North America
File:Sellosaurus.jpg|''[Plateosaurus](/source/Plateosaurus)'' was one of the largest of early [sauropodomorph](/source/sauropodomorph)s, or "prosauropods", of the Late Triassic
File:Coelophysis size flipped.jpg|''[Coelophysis](/source/Coelophysis)'' was one of the most abundant theropod dinosaurs in the Late Triassic
==== Marine reptiles ====
[[File:Triassic marine vertebrate apex predators.png|thumb|upright=1.2|Marine vertebrate apex predators of the [Early Triassic](/source/Early_Triassic) and [Anisian](/source/Anisian) (Middle Triassic)[{{cite journal |last1=Scheyer |first1=Torsten M. |last2=Romano |first2=Carlo |last3=Jenks |first3=Jim |last4=Bucher |first4=Hugo |title=Early Triassic Marine Biotic Recovery: The Predators' Perspective |journal=PLOS ONE |date=19 March 2014 |volume=9 |issue=3 |article-number=e88987 |doi=10.1371/journal.pone.0088987 |doi-access=free |pmid=24647136 |pmc=3960099 }}]]]
There were many types of marine reptiles. These included the [Sauropterygia](/source/Sauropterygia), which featured [pachypleurosaur](/source/pachypleurosaur)s and [nothosaur](/source/nothosaur)s (both common during the Middle Triassic, especially in the [Tethys](/source/Tethys_Ocean) region), [placodont](/source/placodont)s, the earliest known herbivorous marine reptile ''[Atopodentatus](/source/Atopodentatus)'', and the first [plesiosaur](/source/plesiosaur)s. The first of the lizard-like [Thalattosauria](/source/Thalattosauria) (''[Askeptosaurus](/source/Askeptosaurus)'') and the highly successful [ichthyopterygia](/source/ichthyopterygia)ns, which appeared in [Early Triassic](/source/Early_Triassic) seas, soon diversified. By the Middle Triassic, some ichthyopterygians were achieving very large body masses.[{{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 |journal=[Stratigraphy and Geological Correlation](/source/Stratigraphy_and_Geological_Correlation) |volume=32 |issue=3 |pages=242–264 |doi=10.1134/S0869593824030080 |bibcode=2024SGC....32..242Z }}]
==== Other reptiles ====
Among other reptiles, the earliest [turtle](/source/turtle)s, like ''[Proganochelys](/source/Proganochelys)'' and ''[Proterochersis](/source/Proterochersis)'', appeared during the [Norian](/source/Norian) Age (Stage) of the Late Triassic Period. The [Lepidosauromorpha](/source/Lepidosauromorpha), specifically the [Sphenodontia](/source/Sphenodontia), are first found in the fossil record of the earlier Carnian Age, though the earliest lepidosauromorphs likely occurred in the Permian. The [Procolophonidae](/source/Procolophonidae), the last surviving [parareptiles](/source/Parareptilia), were an important group of small lizard-like herbivores. The [drepanosaur](/source/drepanosaur)s were a clade of unusual, chameleon-like arboreal reptiles with birdlike heads and specialised claws.
=== Synapsids ===
Three [therapsid](/source/therapsid) groups survived into the Triassic: [dicynodont](/source/dicynodont)s, [therocephalia](/source/therocephalia)ns, and [cynodont](/source/cynodont)s. The cynodont ''[Cynognathus](/source/Cynognathus)'' was a characteristic top predator in the [Olenekian](/source/Olenekian) and [Anisian](/source/Anisian) of [Gondwana](/source/Gondwana). Both [kannemeyeriiform](/source/Kannemeyeriiformes) dicynodonts and [gomphodont](/source/Gomphodontia) cynodonts remained important [herbivore](/source/herbivore)s during much of the period. Therocephalians included both large predators (''[Moschorhinus](/source/Moschorhinus)'') and herbivorous forms ([bauriids](/source/Bauriidae)) until their extinction midway through the period. [Ecteniniid](/source/Ecteniniidae) cynodonts played a role as large-sized, cursorial predators in the Late Triassic. During the [Carnian](/source/Carnian) (early part of the Late Triassic), some advanced cynodonts gave rise to the [first mammals](/source/Evolution_of_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](/source/evolution_of_mammals) by forcing the surviving therapsids and their [mammaliaform](/source/Mammaliaformes) successors to live as small, mainly nocturnal [insectivore](/source/insectivore)s. [Nocturnal life](/source/Nocturnal_bottleneck) may have forced the mammaliaforms to develop fur and a higher [metabolic rate](/source/Basal_metabolic_rate).[{{cite journal |last1=Ruben |first1=John A. |last2=Jones |first2=Terry D. |title=Selective Factors Associated with the Origin of Fur and Feathers |journal=American Zoologist |date=August 2000 |volume=40 |issue=4 |pages=585–596 |doi=10.1093/icb/40.4.585 |doi-access=free }}]
File:Lystrosaurus BW.jpg|''[Lystrosaurus](/source/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](/source/Cynognathus)'' was a carnivorous [mammal-like](/source/Mammaliaformes) [cynodont](/source/cynodont) from the Early Triassic.
==Lagerstätten==
Two [Early Triassic](/source/Early_Triassic) [lagerstätten](/source/lagerst%C3%A4tten) (high-quality fossil beds), the [Dienerian](/source/Dienerian) aged [Guiyang biota](/source/Guiyang_biota)[{{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 |url=https://u-bourgogne.hal.science/hal-04016004 }}] and the earliest [Spathian](/source/Spathian) aged [Paris biota](/source/Paris_biota)[{{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 }}] stand out due to their exceptional preservation and [diversity](/source/biodiversity). They represent the earliest lagerstätten of the Mesozoic era and provide insight into the biotic recovery from the [Permian-Triassic mass extinction](/source/Permian-Triassic_mass_extinction) event.
The [Monte San Giorgio](/source/Monte_San_Giorgio) lagerstätte, now in the [Lake Lugano](/source/Lake_Lugano) region of northern [Italy](/source/Italy) and southern [Switzerland](/source/Switzerland), was in [Middle Triassic](/source/Middle_Triassic) times a [lagoon](/source/lagoon) behind reefs with an [anoxic](/source/anoxic_waters) 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](/source/Solnhofen_Limestone) [lagerstätte](/source/lagerst%C3%A4tte). The remains of fish and various marine reptiles (including the common [pachypleurosaur](/source/pachypleurosaur) ''[Neusticosaurus](/source/Neusticosaurus)'', and the bizarre long-necked [archosauromorph](/source/archosauromorph) ''[Tanystropheus](/source/Tanystropheus)''), along with some terrestrial forms like ''[Ticinosuchus](/source/Ticinosuchus)'' and ''[Macrocnemus](/source/Macrocnemus)'', have been recovered from this locality. All these fossils date from the [Anisian](/source/Anisian) and [Ladinian](/source/Ladinian) [ages](/source/age_(geology)) (about 242 [Ma](/source/megaannum) ago).
==Triassic–Jurassic extinction event==
{{Main|Triassic–Jurassic extinction event}}
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](/source/conodont)s disappeared, as did all the marine reptiles except [ichthyosaur](/source/Ichthyosauria)s and [plesiosaur](/source/plesiosaur)s. Invertebrates like [brachiopod](/source/brachiopod)s and [mollusc](/source/mollusc)s (such as [gastropod](/source/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 [crurotarsans](/source/Crurotarsi) (large archosaurian reptiles previously grouped together as the [thecodont](/source/Thecodontia)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 [volcanic](/source/volcano) eruptions that occurred as the supercontinent Pangaea began to break apart about 202 to 191 million years ago (40Ar/39Ar dates),[{{cite journal |last1=Nomade |first1=S. |last2=Knight |first2=K.B. |last3=Beutel |first3=E. |last4=Renne |first4=P.R. |last5=Verati |first5=C. |last6=Féraud |first6=G. |last7=Marzoli |first7=A. |last8=Youbi |first8=N. |last9=Bertrand |first9=H. |title=Chronology of the Central Atlantic Magmatic Province: Implications for the Central Atlantic rifting processes and the Triassic–Jurassic biotic crisis |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=February 2007 |volume=244 |issue=1–4 |pages=326–344 |doi=10.1016/j.palaeo.2006.06.034 }}] forming the [Central Atlantic Magmatic Province](/source/Central_Atlantic_Magmatic_Province) (CAMP),[{{cite journal |last1=Marzoli |first1=Andrea |last2=Renne |first2=Paul R. |last3=Piccirillo |first3=Enzo M. |last4=Ernesto |first4=Marcia |last5=Bellieni |first5=Giuliano |last6=Min |first6=Angelo De |title=Extensive 200-Million-Year-Old Continental Flood Basalts of the Central Atlantic Magmatic Province |journal=Science |date=23 April 1999 |volume=284 |issue=5414 |pages=616–618 |doi=10.1126/science.284.5414.616 |pmid=10213679 }}] 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](/source/bolide) impact, for which an impact crater containing [Manicouagan Reservoir](/source/Manicouagan_Reservoir) in [Quebec](/source/Quebec), [Canada](/source/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.[{{cite journal |last1=Hodych |first1=J. P. |last2=Dunning |first2=G. R. |title=Did the Manicouagan impact trigger end-of-Triassic mass extinction? |journal=Geology |date=1992 |volume=20 |issue=1 |page=51 |doi=10.1130/0091-7613(1992)020<0051:DTMITE>2.3.CO;2 }}]
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](/source/Petrified_Forest_National_Park) 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.[{{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}}] [Phytosaur](/source/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](/source/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](/source/therapsid)s—the [kannemeyeriid](/source/Kannemeyeriidae) dicynodonts and the [traversodont](/source/Traversodontidae) cynodonts—were much reduced in the northern half of Pangaea ([Laurasia](/source/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}}
{{Clear}}
==Notes==
{{Reflist|26em}}
==References==
*[Emiliani, Cesare](/source/Cesare_Emiliani). (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](/source/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
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Adapted from the Wikipedia article [Triassic](https://en.wikipedia.org/wiki/Triassic) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Triassic?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.