Editing Triassic (section)

== 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}}</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 |pages=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}}</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 |pages=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  |url=https://doi.org/10.1144/SP295.3 |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 |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>