Editing Reptile (section)

===Research history===
{{See also|Skull roof}}
[[File:Reptile003d.jpg|thumb|right|Reptiles, from ''Nouveau Larousse Illustré'', 1897–1904, notice the inclusion of [[amphibian]]s (below the crocodiles)]]

In the 13th century, the category of ''reptile'' was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians, and worms", as recorded by [[Vincent of Beauvais|Beauvais]] in his ''Mirror of Nature''.<ref>{{cite book | last = Franklin-Brown | first = Mary | year = 2012 | title = Reading the World : Encyclopedic writing in the scholastic age | publisher = The University of Chicago Press | location = Chicago, IL / London, UK | isbn = 9780226260709 |pages=223, 377}}</ref>
In the 18th century, the reptiles were, from the outset of classification, grouped with the [[amphibian]]s. [[Carl Linnaeus|Linnaeus]], working from species-poor [[Sweden]], where the [[common adder]] and [[grass snake]] are often found hunting in water, included all reptiles and amphibians in [[class (biology)|class]] [[Amphibia in the 10th edition of Systema Naturae|{{nobr|"III – Amphibia"}}]] in his ''[[Systema Naturæ]]''.<ref name=Linn1758>{{cite book |last=Linnaeus |first=Carolus |author-link=Carl Linnaeus |year=1758 |title=Systema naturae per regna tria naturae: Secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis |language=la |trans-title=System of Nature through the Three Natural Kingdoms, According to classes, orders, genera, species, with characters, differences, synonyms, places |edition=10th |publisher=Holmiae (Laurentii Salvii) |url=https://www.biodiversitylibrary.org/bibliography/542 |access-date=September 22, 2008}}</ref>
The terms ''reptile'' and ''amphibian'' were largely interchangeable, ''reptile'' (from Latin ''repere'', 'to creep') being preferred by the French.<ref>{{cite encyclopedia |title=Amphibia |encyclopedia=Encyclopædia Britannica |edition=9th |year=1878 |url=http://aleph0.clarku.edu/huxley/UnColl/EnBrit/Amphibia.html}}</ref> [[Josephus Nicolaus Laurenti|J.N. Laurenti]] was the first to formally use the term ''Reptilia'' for an expanded selection of reptiles and amphibians basically similar to that of Linnaeus.<ref>{{cite book |author=Laurenti, J.N. |author-link=Josephus Nicolaus Laurenti |year=1768 |title=Specimen medicum, exhibens synopsin reptilium emendatam cum experimentis circa venena |language=la |trans-title=Medical Specimen: Presenting an improved synopsis of reptiles with experiments on poisons |url=http://gdz.sub.uni-goettingen.de/no_cache/dms/load/img/?IDDOC=281657 |format=facsimile |archive-url=https://web.archive.org/web/20150904013401/http://gdz.sub.uni-goettingen.de/no_cache/dms/load/img/?IDDOC=281657 |archive-date=2015-09-04 }} — shows the mixed composition of ''Reptilia''.</ref> Today, the two groups are still commonly treated under the single heading [[herpetology]].

[[File:MosasaurDiscovery.jpg|thumb|left|"Antediluvian monster", a ''[[Mosasaurus]]'' discovered in a [[Maastricht]] limestone quarry, 1770 (contemporary engraving)]]

It was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, and [[Pierre André Latreille|P.A. Latreille]] erected the class ''Batracia'' (1825) for the latter, dividing the [[tetrapod]]s into the four familiar classes of reptiles, amphibians, birds, and mammals.<ref>{{cite book |author=Latreielle, P.A. |author-link=Pierre André Latreille |year=1804 |title=Nouveau Dictionnaire à Histoire Naturelle |language=fr |trans-title=New Dictionary of Natural History |page=xxiv}} cited in {{cite book |author=Latreille, P.A. |year=1825 |title=Familles naturelles du règne animal, exposés succinctement et dans un ordre analytique |language=fr |trans-title=Natural families of the animal kingdom, succinctly presented in analytical order}}</ref> The British anatomist [[Thomas Henry Huxley|T.H. Huxley]] made Latreille's definition popular and, together with [[Richard Owen]], expanded Reptilia to include the various fossil "[[antediluvian]] monsters", including [[dinosaur]]s and the mammal-like ([[synapsid]]) ''[[Dicynodon]]'' he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the [[Royal College of Surgeons of England|Royal College of Surgeons]] in 1863, Huxley grouped the vertebrates into [[mammal]]s, sauroids, and ichthyoids (the latter containing the fishes and amphibians). He subsequently proposed the names of [[Sauropsida]] and [[Ichthyopsida]] for the latter two groups.<ref>{{cite periodical |author=Huxley, T.H. |author-link=Thomas Henry Huxley |year=1863 |title=The structure and classification of the Mammalia |series=Hunterian lectures |periodical=Medical Times and Gazette |url=http://aleph0.clarku.edu/huxley/UnColl/Gazettes/Mamma.html}}</ref> In 1866, [[Ernst Haeckel|Haeckel]] demonstrated that vertebrates could be divided based on their reproductive strategies, and that reptiles, birds, and mammals were united by the [[amniotic egg]].

The terms ''Sauropsida'' ("lizard faces") and ''[[synapsid|Theropsida]]'' ("beast faces") were used again in 1916 by [[Edwin Stephen Goodrich|E.S. Goodrich]] to distinguish between lizards, birds, and their relatives on the one hand (Sauropsida) and [[mammal]]s and their extinct relatives (Theropsida) on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, and other features, such as the structure of the forebrain. According to Goodrich, both lineages evolved from an earlier stem group, Protosauria ("first lizards") in which he included some animals today considered [[Reptiliomorpha|reptile-like amphibians]], as well as early reptiles.<ref name=goodrich1916>{{cite journal |last=Goodrich |first=E.S. |title=On the classification of the Reptilia |journal=Proceedings of the Royal Society of London B |volume=89 |pages=261–276 |year=1916 |doi=10.1098/rspb.1916.0012 |doi-access=free |issue=615|bibcode=1916RSPSB..89..261G }}</ref>

In 1956, [[D. M. S. Watson|D.M.S. Watson]] observed that the first two groups diverged very early in reptilian history, so he divided Goodrich's Protosauria between them. He also reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included [[Procolophonia]], [[Eosuchia]], [[Millerettid|Millerosauria]], [[Turtle|Chelonia]] (turtles), [[Squamata]] (lizards and snakes), [[Sphenodontia|Rhynchocephalia]], [[Crocodilia]], "[[Thecodontia|thecodonts]]" ([[paraphyly|paraphyletic]] [[basal (phylogenetics)|basal]] [[Archosaur]]ia), non-[[wikt:avian|avian]] [[dinosaur]]s, [[pterosaur]]s, [[ichthyosaur]]s, and [[sauropterygia]]ns.<ref name=watson1956>{{cite journal |last=Watson |first=D.M.S. |year=1957 |title=On millerosaurus and the early history of the sauropsid reptiles |journal=Philosophical Transactions of the Royal Society of London B |volume=240 |issue=673 |pages=325–400 |doi=10.1098/rstb.1957.0003 |doi-access=free |bibcode=1957RSPTB.240..325W}}</ref>

In the late 19th century, a number of definitions of Reptilia were offered. The biological traits listed by [[Richard Lydekker|Lydekker]] in 1896, for example, include a single [[occipital condyle]], a jaw joint formed by the [[Quadrate bone|quadrate]] and [[articular]] bones, and certain characteristics of the [[Vertebral column|vertebrae]].<ref>{{cite book |last=Lydekker |first=Richard |year=1896 |series=The Royal Natural History |title=Reptiles and Fishes |pages=[https://archive.org/details/in.ernet.dli.2015.110219/page/n26 2]–3 |publisher=Frederick Warne & Son |location=London, UK |url=https://archive.org/details/in.ernet.dli.2015.110219 |access-date=March 25, 2016}}</ref> The animals singled out by these formulations, the [[amniote]]s other than the mammals and the birds, are still those considered reptiles today.<ref name="tudge"/>

[[File:Captorhinus aguti p.jpg|thumb|right|The first reptiles had an [[anapsid]] type of [[skull roof]], as seen in the [[Permian]] genus ''[[Captorhinus]]'']]

The synapsid/sauropsid division supplemented another approach, one that split the reptiles into four subclasses based on the number and position of [[temporal fenestra]]e, openings in the sides of the skull behind the eyes. This classification was initiated by [[Henry Fairfield Osborn]] and elaborated and made popular by [[Alfred Romer|Romer]]'s classic ''[[Vertebrate Paleontology (Romer)|Vertebrate Paleontology]]''.<ref>{{cite journal | last1=Osborn | first1=H.F. | author-link=Henry Fairfield Osborn | year=1903 | title=The reptilian subclasses ''Diapsida'' and ''Synapsida'' and [the] early history of ''Diaptosauria'' | journal=Memoirs of the American Museum of Natural History | volume=1 | pages=451–507 }}</ref><ref name=romer1933>{{cite book |last=Romer |first=A.S. |author-link=Alfred Romer |orig-year=1933 |year=1966 |title=Vertebrate Paleontology |edition=3rd |publisher=University of Chicago Press |place=Chicago, IL}}</ref> Those four subclasses were:
* [[Anapsid]]a – no fenestrae – [[Captorhinida|cotylosaurs]] and [[turtle|chelonia]] ([[turtle]]s and relatives){{efn|
This taxonomy does not reflect modern molecular evidence, which places turtles within [[Diapsida]].
}}
* [[Synapsida]] – one low fenestra – [[pelycosaur]]s and [[therapsid]]s (the '[[mammal-like reptiles]]')
* [[Euryapsida]]&nbsp;– one high fenestra (above the postorbital and squamosal)&nbsp;– [[protorosaur]]s (small, early lizard-like reptiles) and the marine [[sauropterygia]]ns and [[ichthyosaurs]], the latter called [[Parapsida]] in Osborn's work.
* [[Diapsid]]a – two fenestrae – most reptiles, including [[lizard]]s, [[snake]]s, [[crocodilian]]s, [[dinosaur]]s and [[pterosaur]]s.

[[File:Varanodon1DB.jpg|thumb|right|Phylogenetic classifications group the traditional "mammal-like reptiles", like this ''[[Varanodon]]'', with other synapsids, not with extant reptiles]]
The composition of Euryapsida was uncertain. [[Ichthyosaurs]] were, at times, considered to have arisen independently of the other euryapsids, and given the older name Parapsida. Parapsida was later discarded as a group for the most part (ichthyosaurs being classified as ''[[incertae sedis]]'' or with Euryapsida). However, four (or three if Euryapsida is merged into Diapsida) subclasses remained more or less universal for non-specialist work throughout the 20th&nbsp;century. It has largely been abandoned by recent researchers: In particular, the anapsid condition has been found to occur so variably among unrelated groups that it is not now considered a useful distinction.<ref>{{cite journal |last1=Tsuji |first1=L.A. |last2=Müller |first2=J. |year=2009 |title=Assembling the History of the Parareptilia: Phylogeny, diversification, and a new definition of the clade |journal=Fossil Record |volume=12 |issue=1 |pages=71–81 |doi=10.1002/mmng.200800011 |bibcode=2009FossR..12...71T |doi-access=free}}</ref>