Editing Pennsylvanian (geology)

{{Short description|Second subperiod of the Carboniferous}}
{{Redirect2|Pennsylvanian period|Late Carboniferous|the train|Pennsylvanian (train)}}
{{Use mdy dates|date=August 2020}}
{{Infobox geologic timespan
| name                         = Pennsylvanian
| color                        = Pennsylvanian
| top_bar                      =
| time_start                   = 323.2
| time_start_uncertainty       = 0.4
| time_end                     = 298.9
| time_end_uncertainty         = 0.15
| image_map                    = Mollweide Paleographic Map of Earth, 310 Ma (Moscovian Age).png
| caption_map                  = A map of Earth as it appeared 310 million years ago during the Pennsylvanian Subperiod, Moscovian Age
| image_outcrop                =
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<!--Chronology-->  
| timeline                     = Carboniferous
<!--Etymology-->
| name_formality               = Formal
| name_accept_date             =
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<!--Usage Information--> 
| celestial_body               = earth
| usage                        = Global ([[International Commission on Stratigraphy|ICS]])
| timescales_used              = ICS Time Scale
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<!--Definition-->
| chrono_unit                  = Subperiod
| strat_unit                   = 
| proposed_by                  =
| timespan_formality           = Formal
| lower_boundary_def           = First appearance of the [[Conodont]] ''[[Declinognathodus|Declinognathodus nodiliferus]]''.
| lower_gssp_location          = Arrow Canyon, Nevada, United States
| lower_gssp_coords            = {{Coord|36.7333|N|114.7778|W|display=inline}}
| lower_gssp_accept_date       = 1996<ref>{{cite journal |last1=Lane |first1=H. |last2=Brenckle |first2=Paul |last3=Baesemann |first3=J. |last4=Richards |first4=Barry |title=The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA |journal=Episodes |date=December 1999 |volume=22 |issue=4 |pages=272–283 |doi=10.18814/epiiugs/1999/v22i4/003 |doi-access=free |url=https://stratigraphy.org/gssps/files/bashkirian.pdf |access-date=8 December 2020}}</ref>
| upper_boundary_def           = First appearance of the [[Conodont]] ''[[Streptognathodus|Streptognathodus isolatus]]'' within the [[morphotype]] ''[[Streptognathodus|Streptognathodus wabaunsensis]]'' chronocline.
| upper_gssp_location          = [[Aidaralash]], [[Ural Mountains]], [[Kazakhstan]]
| upper_gssp_coords            = {{Coord|50.2458|N|57.8914|E|display=inline}}
| upper_gssp_accept_date       = 1996<ref>{{cite journal |last1=Davydov |first1=Vladimir |last2=Glenister |first2=Brian |last3=Spinosa |first3=Claude |last4=Ritter |first4=Scott |last5=Chernykh |first5=V. |last6=Wardlaw |first6=B. |last7=Snyder |first7=W. |title=Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System |journal=Episodes |date=March 1998 |volume=21 |pages=11–18 |doi=10.18814/epiiugs/1998/v21i1/003 |doi-access=free |url=https://stratigraphy.org/gssps/files/asselian.pdf |access-date=7 December 2020}}</ref>
<!--Atmospheric and Climatic Data-->
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The '''Pennsylvanian''' ({{IPAc-en|ˌ|p|ɛ|n|s|əl|ˈ|v|eɪ|n|i|.|ən}} {{respell|pen|səl|VAYN|i|ən}},<ref>{{dictionary.com|Pennsylvanian}}</ref> also known as '''Upper Carboniferous''' or '''Late Carboniferous''') is, on the [[International Commission on Stratigraphy|ICS]] [[geologic timescale]], the younger of two [[period (geology)|subperiods]] of the [[Carboniferous]] Period (or the upper of two [[system (stratigraphy)|subsystems]] of the Carboniferous System). It lasted from roughly {{Period span|Pennsylvanian}}. As with most other [[geochronology|geochronologic]] units, the [[stratum|rock]] beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few hundred thousand years. The Pennsylvanian is named after the U.S. state of [[Pennsylvania]], where the coal [[Bed (geology)|beds]] of this age are widespread.<ref name="Gradstein2005">{{cite book|last1=Gradstein|first1=Felix M.|author-link=Felix M. Gradstein|author2=James G. Ogg|author3=Alan G. Smith|author-link3=Alan Gilbert Smith|title=A Geologic Time Scale 2004|url=https://books.google.com/books?id=rse4v1P-f9kC|year=2005|publisher=Cambridge University Press|isbn=978-0-521-78673-7|page=288}}</ref>

The division between Pennsylvanian and [[Mississippian (geology)|Mississippian]] comes from North American stratigraphy. In North America, where the early [[Carboniferous]] beds are primarily marine [[limestone]]s, the Pennsylvanian was in the past treated as a full-fledged geologic period between the Mississippian and the [[Permian]]. In parts of Europe, the Mississippian and Pennsylvanian are one more-or-less continuous sequence of lowland continental deposits and are grouped together as the Carboniferous Period. The current internationally used geologic timescale of the [[International Commission on Stratigraphy|ICS]] gives the Mississippian and Pennsylvanian the rank of subperiods, subdivisions of the Carboniferous Period.

==Life==
[[File:USGSBulletin1291 mapofUS MiddlePennTime.png|thumb|Generalized geographic map of the United States in middle Pennsylvanian time]]

===Fungi===
All modern [[class (biology)|classes]] of [[fungus|fungi]] have been found in rocks of Pennsylvanian age.<ref>[[Meredith Blackwell|Blackwell, Meredith]], Vilgalys, Rytas, James, Timothy Y., and Taylor, John W. [http://tolweb.org/Fungi/2377/2008.02.21 Fungi. Eumycota: mushrooms, sac fungi, yeast, molds, rusts, smuts, etc.], February 2008, [[Tree of Life Web Project]]</ref>

=== Invertebrates ===
The major forms of life at this time were the arthropods. Arthropods were far larger than modern ones. ''[[Arthropleura]]'', a giant [[millipede]], was a common sight and the giant [[griffinfly]] ''[[Meganeura]]'' "flew the skies".<ref>{{Cite book|title=Fossil Invertebrates|last=Paul D. Taylor|first=David N. Lewis|publisher=The Natural History Museum; First North American edition|year=2005|isbn=0565091832|pages=160}}</ref> It is commonly considered that is because of high oxygen level, however some of those large arthropod records are also known from period with relatively low oxygen, which suggest high oxygen pressure may not have been a primary reason for their gigantism.<ref>{{Cite journal |last1=Gand |first1=G. |last2=Nel |first2=A. N. |last3=Fleck |first3=G. |last4=Garrouste |first4=R. |date=2008-01-01 |title=The Odonatoptera of the Late Permian Lodève Basin (Insecta) |url=https://revistas.ucm.es/index.php/JIGE/article/view/JIGE0808120115A |journal=Journal of Iberian Geology |language=es |volume=34 |issue=1 |pages=115–122 |issn=1886-7995}}</ref><ref>{{Cite journal |last1=Davies |first1=Neil S. |last2=Garwood |first2=Russell J. |last3=McMahon |first3=William J. |last4=Schneider |first4=Joerg W. |last5=Shillito |first5=Anthony P. |date=2021-12-21 |title=The largest arthropod in Earth history: insights from newly discovered''Arthropleura''remains (Serpukhovian Stainmore Formation, Northumberland, England) |url=http://dx.doi.org/10.1144/jgs2021-115 |journal=Journal of the Geological Society |volume=179 |issue=3 |doi=10.1144/jgs2021-115 |issn=0016-7649}}</ref>

===Vertebrates===
[[Amphibian]]s were diverse and common; some were several meters long as adults. The [[Carboniferous Rainforest Collapse|collapse of the rainforest ecology]] in the mid-Pennsylvanian (between the Moscovian and the Kasimovian) removed many amphibian species that did not survive as well in the cooler, drier conditions. Amniotes, however, prospered due to specific key adaptations.<ref name="SahneyBentonFerry2010RainforestCollapse">{{cite journal | last1= Sahney |first1=S. |last2=Benton |first2=M.J. |last3=Falcon-Lang |first3=H.J. | year=2010 | title= Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica | journal=Geology | volume = 38 | pages = 1079–1082 | doi=10.1130/G31182.1 | issue=12}}</ref> One of the greatest evolutionary innovations of the Carboniferous was the [[amniote]] egg, which allowed for the further exploitation of the land by certain [[tetrapod]]s. These included the earliest [[Sauropsida|sauropsid]] reptiles (''[[Hylonomus]]''), and the earliest known "[[pelycosaur]]" [[synapsid]]s (''[[Archaeothyris]]''). Small lizard-like animals quickly gave rise to many descendants. Amniotes underwent a major evolutionary radiation, in response to the drier climate that followed the rainforest [[Ecological collapse|collapse]].

For some reason, pelycosaurs were able to reach larger sizes before reptiles could, and this trend continued until the [[Permian-Triassic extinction event|end of the Permian]], during which their [[cynodont]] descendants became smaller and [[nocturnal bottleneck|nocturnal]], as the reptilian [[archosaurs]] took over, although [[dicynodonts]] would remain megafaunal until their extinction at the [[Triassic-Jurassic extinction event|end of the Triassic]].<ref name="SahneyBentonFerry2010RainforestCollapse"/><ref name=Kazlev>{{cite web |author=Kazlev MA |year=1998 |url=http://palaeos.com/paleozoic/carboniferous/carboniferous.htm |title=Palaeos Paleozoic: Carboniferous: The Carboniferous Period |access-date=March 30, 2012 |archive-url=https://web.archive.org/web/20120309140141/http://palaeos.com/paleozoic/carboniferous/carboniferous.htm |archive-date=March 9, 2012 |url-status=dead }}</ref> Most pre-rainforest collapse tetrapods remained smaller, probably due to the land being primarily occupied by the gigantic millipedes, scorpions, and flying insects. After the rainforest collapse, the giant arthropods disappeared, allowing amniote tetrapods to achieve larger sizes.

==Subdivisions==
The Pennsylvanian has been variously subdivided. The international timescale of the [[International Commission on Stratigraphy|ICS]] follows the Russian subdivision into four stages:<ref name="ICS2013">Cohen ''et al.'' 2013</ref>

*[[Bashkirian]] (oldest)
*[[Moscovian (Carboniferous)|Moscovian]]
*[[Kasimovian]]
*[[Gzhelian]] (youngest)

North American subdivision is into five stages, but not precisely the same, with additional (older) Appalachian series names following:<ref>{{cite web |last1=Rice |first1=Charles L. |title=Pennsylvanian system |url=https://pubs.usgs.gov/pp/p1151h/penn.html |website=Contributions to the geology of Kentucky |publisher=United States Geological Survey |access-date=26 October 2020}}</ref><ref>{{cite journal |last1=Kues |first1=Barry S. |title=The Pennsylvanian System in New Mexico— overview with suggestions for revision of stratigraphic nomenclature |journal=New Mexico Geology |date=November 2001 |pages=103–122 |url=https://geoinfo.nmt.edu/publications/periodicals/nmg/23/n4/nmg_v23_n4_p103.pdf |access-date=26 October 2020}}</ref>

*[[Morrowan]] stage, corresponding with the middle and lower part of the [[Pottsville Group]] (oldest)
*[[Atokan]] stage, corresponding with the upper part of the Pottsville group
*[[Desmoinesian]] stage, corresponding with the [[Allegheny Group]]
*[[Missourian (stage)|Missourian]] stage, corresponding with the [[Conemaugh Group]]
*[[Virgilian series|Virgilian]] stage, corresponding with the [[Monongahela Group]] (youngest)

The Virgilian or Conemaugh corresponds to the Gzhelian plus the uppermost Kasimovian.
The Missourian or Monongahela corresponds to the rest of the Kasimovian.
The Desmoinesian or Allegheny corresponds to the upper half of the Moscovian.
The Atokan or upper Pottsville corresponds to the lower half of the Moscovian.
The Morrowan corresponds to the Bashkirian.

In the European subdivision, the Carboniferous is divided into two epochs: [[Dinantian]] (early) and [[Silesian (series)|Silesian]] (late). The Silesian starts earlier than the Pennsylvanian and is divided in three ages:<ref>{{cite journal |last1=Heckel |first1=P.H. |last2=Clayton |first2=G. |title=The Carboniferous System. Use of the new official names for the subsystems, series, and stages |journal=Geologica Acta |date=2006 |volume=4 |issue=3 |pages=403–407 |doi=10.1344/105.000000354 |url=https://ddd.uab.cat/pub/geoact/geoact_a2006v4n3/geoact_a2006v4n3p403.pdf |access-date=26 October 2020}}</ref>
*[[Namurian]] (corresponding to [[Serpukhovian]] and early Bashkirian)
*[[Westphalian (stage)|Westphalian]] (corresponding to late Bashkirian, Moskovian and Kasimovian)
*[[Stephanian (stage)|Stephanian]] (corresponding to Gzhelian).

==References==
{{reflist}}

== External links ==
* [https://web.archive.org/web/20100702114906/http://www.scotese.com/late.htm The Late Carboniferous a Time of Great Coal Swamps], Paleomap project. World map from this time period.
* [http://www.ucmp.berkeley.edu/carboniferous/carboniferous.html The Carboniferous – 354 to 290 Million Years Ago], [[University of California Museum of Paleontology]]. Information on stratigraphies, localities, tectonics, and life.
* [https://web.archive.org/web/20050305064050/http://www.palaeos.com/Paleozoic/Carboniferous/Pennsylvanian.htm The Pennsylvanian Epoch of the Carboniferous Period: 318 to 299 Mya], Paleos.com
* [https://pubs.usgs.gov/imap/i-2768/i2768.pdf US Geological Survey comparison of time scales]

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[[Category:Pennsylvanian (geology)| ]]
[[Category:Pennsylvanian geochronology| ]]
[[Category:Carboniferous geochronology|*02]]
[[Category:Geological epochs]]
[[Category:Carboniferous United States|*]]