Editing Marine reptile

{{Short description|Aquatically secondarily adapted reptiles}}
[[Image:Modern-marine-reptiles-001.jpg|thumb|Extant Cenozoic marine reptiles:<br />
{{*}} [[Saltwater crocodile]] (top left)<br />
{{*}} [[Sea turtle]] (top right)<br />
{{*}} [[Marine iguana]] (bottom left)<br />
{{*}} [[Sea snake]] (bottom right)]]

'''Marine reptiles''' are [[reptile]]s which have become secondarily [[adaptation|adapted]] for an [[aquatic animal|aquatic]] or [[semiaquatic]] life in a [[marine ecosystem|marine]] [[Natural environment|environment]]. Only about 100 of the 12,000 [[Extant taxon|extant]] reptile species and subspecies are classed as marine reptiles, including [[marine iguana]]s, [[sea snake]]s, [[sea turtle]]s and [[saltwater crocodile]]s.<ref name=":0">{{Cite journal |last1=Rasmussen |first1=Arne Redsted |last2=Murphy |first2=John C. |last3=Ompi |first3=Medy |last4=Gibbons |first4=J. Whitfield |last5=Uetz |first5=Peter |date=2011-11-08 |title=Marine Reptiles |journal=PLOS ONE |volume=6 |issue=11 |pages=e27373 |bibcode=2011PLoSO...627373R |doi=10.1371/journal.pone.0027373 |pmc=3210815 |pmid=22087300 |doi-access=free}}</ref>

The earliest marine reptile was ''[[Mesosaurus]]'' (not to be confused with ''[[Mosasaurus]]''), which arose in the [[Permian]] period of the [[Paleozoic]] era.<ref>{{cite journal |last1=Piñeiro |first1=Graciela |last2=Ferigolo |first2=Jorge |last3=Ramos |first3=Alejandro |last4=Laurin |first4=Michel |title=Cranial morphology of the Early Permian mesosaurid Mesosaurus tenuidens and the evolution of the lower temporal fenestration reassessed |journal=Comptes Rendus Palevol |date=1 July 2012 |volume=11 |issue=5 |pages=379–391 |doi=10.1016/j.crpv.2012.02.001 |bibcode=2012CRPal..11..379P }}</ref> During the [[Mesozoic]] era, many groups of reptiles became adapted to life in the seas, including such familiar clades as the [[ichthyosaur]]s, [[plesiosaur]]s (these two orders were once thought united in the group "Enaliosauria",<ref>Williston SW (1914) [https://books.google.com/books?id=uB7YkzwYaswC&dq=enaliosauria+ichthyosauria&pg=PA75 ''Water Reptiles of the Past and Present''] University of Chicago Press (reprint 2002). {{ISBN|1-4021-4677-9}}</ref> a classification now cladistically obsolete), [[mosasaur]]s, [[nothosaur]]s, [[placodont]]s, [[sea turtle]]s, [[thalattosaur]]s and [[thalattosuchia]]ns. Most marine reptile groups became extinct at the end of the [[Cretaceous]] period, but some still existed during the Cenozoic, most importantly the [[sea turtles]]. Other Cenozoic marine reptiles included the [[Bothremydidae|bothremydids]],<ref>{{cite journal |last1=Carvalho |first1=Anny Rafaela De Araújo |last2=Ghilardi |first2=Aline Marcele |last3=Barreto |first3=Alcina Magnólia Franca |title=A new side-neck turtle (Pelomedusoides: Bothremydidae) from the Early Paleocene (Danian) Maria Farinha Formation, Paraíba Basin, Brazil |journal=Zootaxa |date=21 June 2016 |volume=4126 |issue=4 |pages=491–513 |doi=10.11646/zootaxa.4126.4.3 |pmid=27395602 }}</ref> [[Palaeophiidae|palaeophiid]] snakes, a few [[Choristodera|choristodere]]s such as ''[[Simoedosaurus]]'' and [[dyrosaurid]] crocodylomorphs. Various types of marine [[gavialid]] crocodilians remained widespread as recently as the Late Miocene.<ref>{{cite book |last1=Langston |first1=Wann |last2=Gasparini |first2=Z. |chapter=Crocodilians, Gryposuchus, and the South American gavials |pages=113–154 |editor1-last=Kay |editor1-first=Richard F |editor2-last=Madden |editor2-first=Richard H |editor3-last=Cifelli |editor3-first=Richard L |editor4-last=Flynn |editor4-first=John J. |title=Vertebrate paleontology in the neotropics: the Miocene fauna of La Venta, Colombia |date=1997 |publisher=Smithsonian Institution Press |isbn=978-1-56098-418-4 }}</ref>

Some marine reptiles, such as ichthyosaurs, plesiosaurs, [[Metriorhynchidae|metriorhynchid]] thalattosuchians, and mosasaurs became so well adapted to a marine lifestyle that they were incapable of venturing onto land and gave birth in the water. Others, such as sea turtles and saltwater crocodiles, return to shore to lay their eggs. Some marine reptiles also occasionally rest and [[wikt:bask|bask]] on land.

== Extant groups ==
[[Image:Eretmochelys-imbricata-Kélonia-2.JPG|thumb|[[Hawksbill sea turtle]] (''Eretmochelys imbricata'')]]

* '''[[Sea turtle]]s:''' there are seven extant species of sea turtles, which live mostly along the tropical and subtropical coastlines, though some do migrate long distances and have been known to travel as far north as Scandinavia. Sea turtles are largely solitary animals, though some do form large, though often loosely connected groups during nesting season. Although only seven turtle species are truly marine, many more dwell in brackish waters.<ref name=":0" /><ref name=":1">{{Cite web|url = http://www.britannica.com/animal/sea-turtle|title = Sea Turtle|access-date = December 8, 2015|website = Encyclopædia Britannica Online|last = Zug|first = George R.}}</ref>
* '''[[Sea snakes]]''': the most abundant of the marine reptiles, there are over 60 different species of sea snakes. They inhabit the tropical and subtropical waters of the [[Indian Ocean|Indian]] and [[Pacific Ocean|Pacific oceans]], though very limited reports of sightings suggest they may be extending into the [[Atlantic Ocean]]. Sea snakes are venomous and their bites have been known to be fatal, though generally they only bite when provoked and often inject only a very small, non-fatal quantity of venom. Sea snakes are distinguished from terrestrial snakes by a vertically flattened tail.<ref name=":0" /><ref>{{Cite web|url = http://www.britannica.com/animal/sea-snake|title = Sea Snake|access-date = December 8, 2015|website = Encyclopædia Britannica Online}}</ref>
* '''[[Marine iguana]]''': marine iguanas live only on the [[Galápagos Islands]] and are not fully adapted to marine life. Although they feed exclusively on [[marine plants]] and spend a good deal of their time in the water, they do nest on land and need to bask in the sun to reach their ideal body temperature; they are thus also subject to terrestrial predators.<ref name=":0" /><ref>{{Cite web|url = http://animals.nationalgeographic.com/animals/reptiles/marine-iguana/?source=A-to-Z|archive-url = https://web.archive.org/web/20110521013313/http://animals.nationalgeographic.com/animals/reptiles/marine-iguana/?source=A-to-Z|url-status = dead|archive-date = May 21, 2011|title = Marine Iguanas|access-date = December 8, 2015|website = National Geographic}}</ref>
* '''[[Saltwater crocodile|Saltwater]] and [[American crocodile]]s''': none of the extant species of crocodiles are truly marine; however, the saltwater crocodile (''Crocodylus porosus'') does display adaptations to saltwater inhabitation and dwells in the brackish waters of Southeast Asia and Australia. Saltwater crocodiles dispose of excess salt in their bodies through specialized [[salt gland]]s. These are the largest species of crocodile, also making them the largest [[reptiles]]. They can grow up to six meters in length.<ref name=":0" /><ref name=":2">{{Cite web|url = http://animals.nationalgeographic.com/animals/reptiles/saltwater-crocodile/|archive-url = https://web.archive.org/web/20100204214413/http://animals.nationalgeographic.com/animals/reptiles/saltwater-crocodile|url-status = dead|archive-date = February 4, 2010|title = Saltwater crocodile|access-date = December 8, 2015|website = National Geographic}}</ref> American crocodiles (''Crocodylus acutus'') similarly prefer brackish over freshwater habitats.<ref name="Ellis1981">{{cite journal|last1= Ellis|first1=T. M.|title= Tolerance of Sea Water by the American Crocodile, ''Crocodylus acutus''|journal= Journal of Herpetology|volume= 15|issue= 2|year= 1981|pages= 187–192|doi= 10.2307/1563379|jstor=1563379}}</ref>

==Extinct groups==
[[File:OphthalmosaurusIcenius-NaturalHistoryMuseum-August23-08.jpg|thumb|Fossil of ''[[Ophthalmosaurus icenius]]'', a species of ichthyosaur]]
*'''[[Ichthyosaur]]s''' were marine reptiles with a dolphin-like body shape that flourished during the Mesozoic era.
*'''[[Sauropterygia]]ns''' were a diverse group of aquatic reptiles adapted for flipper-based aquatic locomotion. This group included the [[plesiosaur]]s, [[nothosaur]]s, and [[placodont]]s.
*'''[[Mosasaur]]s''' were a group of large, aquatic [[squamate]]s (relatives of modern-day lizards and snakes) which became the dominant marine predators towards the end of the Cretaceous period.
*'''[[Thalattosaur]]s''' were a group of aquatic or semiaquatic marine reptiles of uncertain placement within the [[diapsid]] clade. One subgroup, the [[thalattosauroid]]s, are known for their unusual downturned snouts and crushing dentition.
*'''[[Mesosaur]]s''' were quite possibly the first fully aquatic reptilian animals and the only group known from the [[Paleozoic]], though they are technically not true reptiles in the sense of not being part of the [[diapsid]] group. Taxonomic placement either puts these Permian animals resembling long-snouted lizards with newt-like tails either as members of [[Parareptilia]] or as a type of [[Synapsid]].
*'''[[Thalattosuchia]]ns''' were marine [[crocodylomorph]]s that flourished during the Jurassic period.

==Adaptation to the marine environment==
{{main|Physiology of underwater diving#Aquatic reptiles}}
{{empty section|date=February 2020}}

== Conservation ==
Most species of marine reptiles are considered endangered to some degree. All but one species of sea turtles are endangered due to destruction of nesting habitats on coastal lands, exploitation, and marine fishing;<ref name=":1" /> many species of sea snakes are threatened or endangered due to commercial exploitation (sale of skins) and pollution especially in Asia; marine iguanas are threatened due to their very limited habitation range.<ref name=":0" /> Saltwater crocodiles are at low risk for extinction.<ref name=":2" />

==See also==
*[[List of marine reptiles]]
* {{portal-inline|Reptiles}}

==References==
{{Reflist}}

{{aquatic ecosystem topics|expanded=marine}}

{{DEFAULTSORT:Marine Reptile}}
[[Category:Marine reptiles|*]]