Editing Triassic–Jurassic extinction event (section)

=== Marine vertebrates ===
[[File:Euconodonta.gif|left|thumb|Conodonts were a major vertebrate group which died out at the end of the Triassic]]
Fish did not suffer a mass extinction at the end of the Triassic. The Late Triassic in general did experience a gradual drop in [[actinopterygii]]an diversity after an evolutionary explosion in the [[Middle Triassic]]. Though this may have been due to falling sea levels or the [[Carnian Pluvial Event]], it may instead be a result of [[sampling bias]] considering that Middle Triassic fish have been more extensively studied than Late Triassic fish.<ref>{{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|date=27 November 2014|title=Permian–Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution|url=https://www.researchgate.net/publication/268810424|journal=[[Biological Reviews of the Cambridge Philosophical Society]]|volume=91|issue=1|pages=106–147|doi=10.1111/brv.12161|issn=1469-185X|pmid=25431138|s2cid=5332637}}</ref> Despite the apparent drop in diversity, [[neopterygii]]ans (which include most modern bony fish) suffered less than more "primitive" actinopterygiians, indicating a biological turnover where modern groups of fish started to supplant earlier groups.<ref name="TannerLucas" /> Pycnodontiform fish were insignificantly affected.<ref>{{Cite journal |last1=Stumpf |first1=Sebastian |last2=Ansorge |first2=Jörg |last3=Pfaff |first3=Cathrin |last4=Kriwet |first4=Jürgen |date=4 July 2017 |title=Early Jurassic diversification of pycnodontiform fishes (Actinopterygii, Neopterygii) after the end-Triassic extinction event: evidence from a new genus and species, Grimmenodon aureum |journal=[[Journal of Vertebrate Paleontology]] |language=en |volume=37 |issue=4 |pages=e1344679 |doi=10.1080/02724634.2017.1344679 |issn=0272-4634 |pmc=5646184 |pmid=29170576 }}</ref> [[Conodont]]s, which were prominent index fossils throughout the Paleozoic and Triassic, finally became extinct at the T-J boundary following declining diversity.<ref name="TannerLucas" />

Like fish, marine reptiles experienced a substantial drop in diversity between the Middle Triassic and the Jurassic. However, their extinction rate at the Triassic–Jurassic boundary was not elevated. The highest extinction rates experienced by Mesozoic marine reptiles actually occurred at the end of the [[Ladinian]] stage, which corresponds to the end of the Middle Triassic. The only marine reptile [[Family (biology)|families]] which became extinct at or slightly before the Triassic–Jurassic boundary were the [[Placochelyidae|placochelyids]] (the last family of [[Placodontia|placodonts]]), making [[plesiosaur]]s the only surviving [[sauropterygia]]ns,<ref>{{cite journal | pmc=6873879 | date=2019 | last1=Fleischle | first1=C. V. | last2=Sander | first2=P. M. | last3=Wintrich | first3=T. | last4=Caspar | first4=K. R. | title=Hematological convergence between Mesozoic marine reptiles (Sauropterygia) and extant aquatic amniotes elucidates diving adaptations in plesiosaurs | journal=PeerJ | volume=7 | pages=e8022 | doi=10.7717/peerj.8022 | doi-access=free | pmid=31763069 }}</ref> and giant [[ichthyosaur]]s such as [[Shastasauridae|shastasaurids]].<ref>{{Cite journal|last=Bardet|first=Nathalie|date=1994-07-01|title=Extinction events among Mesozoic marine reptiles|journal=[[Historical Biology]]|volume=7|issue=4|pages=313–324|doi=10.1080/10292389409380462|bibcode=1994HBio....7..313B |issn=0891-2963|url=http://doc.rero.ch/record/15138/files/PAL_E2412.pdf }}</ref> Some authors have argued that the end of the Triassic acted as a genetic "[[Population bottleneck|bottleneck]]" for ichthyosaurs, which never regained the level of anatomical diversity and disparity which they possessed during the Triassic,<ref>{{Cite journal|last1=Thorne|first1=Philippa M.|last2=Ruta|first2=Marcello|last3=Benton|first3=Michael J.|date=17 May 2011|title=Resetting the evolution of marine reptiles at the Triassic–Jurassic boundary|journal=[[Proceedings of the National Academy of Sciences of the United States of America]]|language=en|volume=108|issue=20|pages=8339–8344|doi=10.1073/pnas.1018959108|issn=0027-8424|pmid=21536898|pmc=3100925|bibcode=2011PNAS..108.8339T|doi-access=free}}</ref> although analysis of ichthyosaurian and eosauropterygian disparity across the Triassic-Jurassic transition has shown no evidence for such a bottleneck.<ref>{{Cite journal |last=Laboury |first=Antoine |last2=Stubbs |first2=Thomas L. |last3=Wolniewicz |first3=Andrzej S. |last4=Liu |first4=Jun |last5=Scheyer |first5=Torsten M. |last6=Jones |first6=Marc E H |last7=Fischer |first7=Valentin |date=22 December 2024 |editor-last=Parins-Fukuchi |editor-first=Tomomi |editor2-last=Morlon |editor2-first=Hélène |title=Contrasting macroevolutionary patterns in pelagic tetrapods across the Triassic–Jurassic transition |url=https://academic.oup.com/evolut/article/79/1/38/7758686 |journal=[[Evolution (journal)|Evolution]] |language=en |volume=79 |issue=1 |pages=38–50 |doi=10.1093/evolut/qpae138 |issn=0014-3820 |access-date=18 February 2025 |via=Oxford Academic}}</ref> The high diversity of rhomaelosaurids immediately after the TJME points to a gradual extinction of marine reptiles rather than an abrupt one.<ref>{{Cite journal |last1=Benson |first1=Roger B. J. |last2=Evans |first2=Mark |last3=Druckenmiller |first3=Patrick S. |date=16 March 2012 |editor-last=Lalueza-Fox |editor-first=Carles |title=High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary |journal=PLOS ONE |language=en |volume=7 |issue=3 |pages=e31838 |doi=10.1371/journal.pone.0031838 |doi-access=free |issn=1932-6203 |pmc=3306369 |pmid=22438869 }}</ref>