Editing Devonian (section)

==History ==
[[File:Lummaton Quarry 1.JPG|thumb|The rocks of Lummaton Quarry in [[Torquay]] in [[Devon]] played an early role in defining the Devonian Period|left]]
The period is named after [[Devon]], a county in southwestern England, where a controversial argument in the 1830s over the age and structure of the rocks found throughout the county was resolved by adding the Devonian Period to the geological timescale. [[The Great Devonian Controversy]] was a lengthy debate between [[Roderick Murchison]], [[Adam Sedgwick]] and [[Henry De la Beche]] over the naming of the period. Murchison and Sedgwick won the debate and named it the Devonian System.<ref>{{harvtxt|Gradstein|Ogg|Smith|2004}}</ref><ref>{{cite book |last=Rudwick |first=M.S.J. |date=1985 |title=The great Devonian controversy: The shaping of scientific knowledge among gentlemanly specialists |url=https://archive.org/details/greatdevoniancon0000rudw |url-access=registration |location=Chicago |publisher=University of Chicago Press |isbn=978-0226731025}}</ref>{{efn|text= Sedgwick and Murchison coined the term "Devonian system" in 1840:<ref>{{cite encyclopedia |first1=Adam |last1=Sedgwick |first2=Roderick Impey |last2=Murchison |year=1840 |title=On the physical structure of Devonshire, and on the subdivisions and geological relations of its older stratified deposits, etc. Part I and Part II |encyclopedia=Transactions of the Geological Society of London |series=Second series |volume=5 part&nbsp;II |url=https://books.google.com/books?id=QknWzPRnVRQC&pg=PA701 |page=701}}</ref> "We propose therefore, for the future, to designate these groups collectively by the name ''Devonian system''". Sedgwick and Murchison acknowledged William Lonsdale's role in proposing, on the basis of fossil evidence, the existence of a Devonian stratum between those of the Silurian and Carboniferous periods:{{sfn|Sedgwick|Murchison|1840|p=690}} "Again, Mr.&nbsp;Lonsdale, after an extensive examination of the fossils of South Devon, had pronounced them, more than a year since, to form ''a group intermediate between those of the Carboniferous and Silurian systems''".

William Lonsdale stated that in December 1837 he had suggested the existence of a stratum between the Silurian and Carboniferous ones:<ref>{{cite encyclopedia |first1=William |last1=Lonsdale |date=1840 |url=https://books.google.com/books?id=QknWzPRnVRQC&pg=PA721 |title=Notes on the age of limestones from south Devonshire |encyclopedia=Transactions of the Geological Society of London |series=Second series |volume=5 part&nbsp;II |page=724}}</ref> "Mr.&nbsp;Austen's communication [was] read December&nbsp;1837 ...&nbsp;. It was immediately after the reading of that paper ... that I formed the opinion relative to the limestones of Devonshire being of the age of the old red sandstone; and which I afterwards suggested first to Mr.&nbsp;Murchison and then to Prof.&nbsp;Sedgwick".}}

While the [[stratum|rock bed]]s that define the start and end of the Devonian Period are well identified, the exact dates are uncertain. According to the [[International Commission on Stratigraphy]],{{sfn|Gradstein|Ogg|Smith|2004}} the Devonian extends from the end of the Silurian {{Period end|Silurian}} Ma, to the beginning of the [[Carboniferous]] {{Period start|Carboniferous}} Ma – in [[North America]], at the beginning of the [[Mississippian (geology)|Mississippian subperiod]] of the Carboniferous.

In 19th-century texts, the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the [[Old Red Sandstone]] in which early fossil discoveries were found. Another common term is "Age of the Fishes",<ref>{{cite web |url=http://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPaleo4.html#The%20Devonian |title=Paleobiology: The Late Paleozoic: Devonian |last=Farabee |first=Michael J. |website=The Online Biology Book |publisher=Estrella Mountain Community College |date=2006}}</ref> referring to the evolution of several major groups of [[fish]] that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian, Breconian, and Farlovian stages, the latter three of which are placed in the Devonian.<ref>{{cite encyclopedia |last1=Barclay |first1=W.J. |date=1989 |title=Geology of the South Wales Coalfield Part&nbsp;II, the country around Abergavenny |edition=3rd |series=Memoir for 1:50,000 geological sheet (England and Wales) |number=232 |pages=18–19 |isbn=0-11-884408-3}}</ref>

The Devonian has also erroneously been characterised as a "greenhouse age", due to [[sampling bias]]: most of the early Devonian-age discoveries came from the [[stratum|strata]] of [[Western Europe]] and eastern [[North America]], which at the time straddled the [[Equator]] as part of the supercontinent of Euramerica where [[fossil]] signatures of widespread reefs indicate tropical [[climate]]s that were warm and moderately humid. In fact, the climate in the Devonian differed greatly during its [[geologic time scale|epochs]] and between geographic regions. For example, during the Early Devonian, arid conditions were prevalent through much of the world including Siberia, Australia, North America, and China, but Africa and [[South America]] had a warm [[temperate climate]]. In the Late Devonian, by contrast, arid conditions were less prevalent across the world and [[temperate climate]]s were more common.{{Citation needed|date=December 2017}}