Editing Jurassic (section)

==== Early Jurassic ====
The oldest part of the Jurassic Period has historically been referred to as the Lias or Liassic, roughly equivalent in extent to the Early Jurassic, but also including part of the preceding [[Rhaetian]]. The Hettangian Stage was named by Swiss palaeontologist [[Eugène Renevier]] in 1864 after [[Hettange-Grande]] in north-eastern France.<ref name="Ogg-2012" /> The GSSP for the base of the Hettangian is located at the Kuhjoch Pass, [[Karwendel|Karwendel Mountains]], [[Northern Limestone Alps|Northern Calcareous Alps]], Austria; it was ratified in 2010. The beginning of the Hettangian, and thus the Jurassic as a whole, is marked by the [[First appearance datum|first appearance]] of the ammonite ''[[Psiloceras|Psiloceras spelae tirolicum]]'' in the [[Kendlbach Formation]] exposed at Kuhjoch.<ref>{{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.|date=2013-09-01|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|language=en|volume=36|issue=3|pages=162–198|doi=10.18814/epiiugs/2013/v36i3/001|issn=0705-3797|doi-access=free}}</ref> The base of the Jurassic was previously defined as the first appearance of ''Psiloceras planorbis'' by Albert Oppel in 1856–58, but this was changed as the appearance was seen as too localised an event for an international boundary.<ref name="Ogg-2012" />

The Sinemurian Stage was first defined and introduced into scientific literature by Alcide d'Orbigny in 1842. It takes its name from the French town of [[Semur-en-Auxois]], near [[Dijon]]. The original definition of Sinemurian included what is now the Hettangian. The GSSP of the Sinemurian is located at a cliff face north of the hamlet of [[East Quantoxhead]], 6 kilometres east of [[Watchet]], [[Somerset]], [[England]], within the [[Blue Lias]], and was ratified in 2000. The beginning of the Sinemurian is defined by the first appearance of the ammonite ''[[Vermiceras|Vermiceras quantoxense]].''<ref name="Ogg-2012">{{Citation|last1=Ogg|first1=J.G.|title=Jurassic|date=2012|url=https://linkinghub.elsevier.com/retrieve/pii/B9780444594259000263|work=The Geologic Time Scale|pages=731–791|publisher=Elsevier|language=en|doi=10.1016/b978-0-444-59425-9.00026-3|isbn=978-0-444-59425-9|access-date=2020-12-05|last2=Hinnov|first2=L.A.|last3=Huang|first3=C.}}</ref><ref>{{Cite journal|last1=Bloos|first1=Gert|last2=Page|first2=Kevin N.|date=2002-03-01|title=Global Stratotype Section and Point for base of the Sinemurian Stage (Lower Jurassic)|journal=Episodes|volume=25|issue=1|pages=22–28|doi=10.18814/epiiugs/2002/v25i1/003|issn=0705-3797|doi-access=free}}</ref>

Albert Oppel in 1858 named the Pliensbachian Stage after the hamlet of [[Pliensbach]] in the community of [[Zell unter Aichelberg]] in the [[Swabian Alb]], near [[Stuttgart]], Germany. The GSSP for the base of the Pliensbachian is found at the Wine Haven locality in [[Robin Hood's Bay]], [[Yorkshire]], England, in the [[Redcar Mudstone Formation]], and was ratified in 2005. The beginning of the Pliensbachian is defined by the first appearance of the ammonite ''[[Bifericeras|Bifericeras donovani]]''.<ref>{{Cite journal|last1=Meister|first1=Christian|last2=Aberhan|first2=Martin|last3=Blau|first3=Joachim|last4=Dommergues|first4=Jean-Louis|last5=Feist-Burkhardt|first5=Susanne|last6=Hailwood|first6=Ernie A.|last7=Hart|first7=Malcom|last8=Hesselbo|first8=Stephen P.|last9=Hounslow|first9=Mark W.|last10=Hylton|first10=Mark|last11=Morton|first11=Nicol|date=2006-06-01|title=The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic), Wine Haven, Yorkshire, UK|journal=Episodes|volume=29|issue=2|pages=93–106|doi=10.18814/epiiugs/2006/v29i2/003|issn=0705-3797|doi-access=free}}</ref>

The village [[Thouars]] (Latin: ''Toarcium''), just south of [[Saumur]] in the [[Loire Valley]] of [[France]], lends its name to the Toarcian Stage. The Toarcian was named by Alcide d'Orbigny in 1842, with the original locality being Vrines quarry around 2&nbsp;km northwest of Thouars. The GSSP for the base of the Toarcian is located at [[Peniche, Portugal]], and was ratified in 2014. The boundary is defined by the first appearance of ammonites belonging to the subgenus ''[[Dactylioceras]]'' [[Dactylioceras|(''Eodactylites'')]]''.''<ref>{{Cite journal|last1=Rocha|first1=Rogério Bordalo da|last2=Mattioli|first2=Emanuela|last3=Duarte|first3=Luís Vítor|last4=Pittet|first4=Bernard|last5=Elmi|first5=Serge|last6=Mouterde|first6=René|last7=Cabral|first7=Maria Cristina|last8=Comas-Rengifo|first8=Maria José|last9=Gómez|first9=Juan José|last10=Goy|first10=António|last11=Hesselbo|first11=Stephen P.|date=2016-09-01|title=Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)|journal=Episodes|language=en|volume=39|issue=3|pages=460–481|doi=10.18814/epiiugs/2016/v39i3/99741|s2cid=131791652 |issn=0705-3797|doi-access=free|hdl=10261/140775|hdl-access=free}}</ref>