Editing Paleozoic (section)

==Geology==
The beginning of the Paleozoic Era witnessed the breakup of the supercontinent of [[Pannotia]]<ref name=Scotese-2009>
{{cite journal |last=Scotese |first=C.R. |year=2009 |title=Late Proterozoic plate tectonics and palaeogeography: A tale of two supercontinents, Rodinia and Pannotia |journal=Geological Society, London, Special Publications |volume=326 |issue=1 |page=68 |doi=10.1144/SP326.4 |bibcode=2009GSLSP.326...67S |s2cid=128845353 |url=https://www.researchgate.net/publication/249552299 |access-date=29 November 2015}}
</ref><ref name=Murphy-Nance-Cawood-2009>
{{cite journal |last1=Murphy |first1=J.B. |last2=Nance |first2=R.D. |last3=Cawood |first3=P.A. |name-list-style=amp |year=2009 |title=Contrasting modes of supercontinent formation and the conundrum of Pangea |journal=Gondwana Research |volume=15 |issue=3 |pages=408–20 |doi=10.1016/j.gr.2008.09.005 |bibcode=2009GondR..15..408M |url=https://www.researchgate.net/publication/222153136 |access-date=20 December 2019}}
</ref>
and ended while the supercontinent [[Pangaea]] was assembling.<ref name=Rogers-Santosh-2004>
{{cite book |author1=Rogers, J.J.W. |author2=Santosh, M. |name-list-style=amp |year=2004 |title=Continents and Supercontinents |publisher=Oxford University Press |place=Oxford, UK |isbn=978-0-19-516589-0 |page=146}}
</ref>
The breakup of Pannotia began with the opening of the [[Iapetus Ocean]] and other Cambrian seas and coincided with a dramatic rise in sea level.<ref name=Dalziel-1997>
{{cite journal |last=Dalziel |first=I.W. |year=1997 |title=Neoproterozoic-Paleozoic geography and tectonics: Review, hypothesis, environmental speculation |journal=Geological Society of America Bulletin |volume=109 |issue=1 |pages=16–42 |doi=10.1130/0016-7606(1997)109<0016:ONPGAT>2.3.CO;2 |bibcode=1997GSAB..109...16D}}
</ref>
[[Paleoclimatology|Paleoclimatic]] studies and evidence of [[glacier]]s indicate that [[Central Africa]] was most likely in the polar regions during the early Paleozoic. The breakup of Pannotia was followed by the assembly of the huge continent [[Gondwana]] ({{Ma|510}}). By the mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, and a subducting plate uplifted eastern [[Australia]]. By the late Paleozoic, continental collisions formed the supercontinent of Pangaea and created great mountain chains, including the [[Appalachians]], [[Caledonides]], [[Ural Mountains]], and mountains of [[Tasmania]].<ref name=Rogers-Santosh-2004/>

=== Cambrian Period ===
{{main|Cambrian}}
[[File:Trilobite Heinrich Harder.jpg|thumb|left|[[Trilobite]]s]]
The Cambrian spanned from 539–485&nbsp;million years ago and is the first period of the Paleozoic Era of the Phanerozoic. The Cambrian marked a boom in evolution in an event known as the [[Cambrian explosion]] in which the largest number of creatures evolved in any single period of the history of the Earth. Creatures like [[algae]] evolved, but the most ubiquitous of that period were the armored arthropods, like trilobites. Almost all marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, most of which later became the supercontinent Gondwana.<ref>{{cite web |title=Cambrian |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=[[University of California Museum of Paleontology]] |url=http://www.ucmp.berkeley.edu/cambrian/cambrian.php |access-date=2015-04-26 |archive-date=2012-05-15 |archive-url=https://web.archive.org/web/20120515190500/http://www.ucmp.berkeley.edu/cambrian/cambrian.php |url-status=live }}</ref>
{{Clear}}

=== Ordovician Period ===
{{main|Ordovician}}

[[File:Ostracoderm digital recreation..jpg|thumb|[[Cephalaspis]] (a jawless fish)]]
The Ordovician spanned from 485–444&nbsp;million years ago. The Ordovician was a time in Earth's history in which many of the [[Class (biology)|biological class]]es still prevalent today evolved, such as primitive fish, cephalopods, and coral. The most common forms of life, however, were trilobites, snails and shellfish. The first arthropods went ashore to colonize the empty continent of Gondwana. By the end of the Ordovician, Gondwana was at the south pole, early North America had collided with Europe, closing the intervening ocean. Glaciation of Africa resulted in a major drop in sea level, killing off all life that had established along coastal Gondwana. Glaciation may have caused the [[Ordovician–Silurian extinction events]], in which 60% of marine invertebrates and 25% of families became extinct, and is considered the first Phanerozoic mass extinction event, and the second deadliest.{{efn|name=only-counting-Phanerozoic-extinctions-note}}<ref>{{cite web |title=Ordovician |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=[[University of California Museum of Paleontology]] |url=http://www.ucmp.berkeley.edu/ordovician/ordovician.php |access-date=2015-04-26 |archive-date=2015-05-02 |archive-url=https://web.archive.org/web/20150502201732/http://www.ucmp.berkeley.edu/ordovician/ordovician.php |url-status=live }}</ref>

=== Silurian Period ===
{{main|Silurian}}

The Silurian spanned from 444–419&nbsp;million years ago. The Silurian saw the rejuvenation of life as the Earth recovered from the previous glaciation. This period saw the mass evolution of fish, as jawless fish became more numerous, jawed fish evolved, and the first freshwater fish evolved, though arthropods, such as [[Eurypterida|sea scorpions]], were still [[apex predator]]s. Fully terrestrial life evolved, including early arachnids, fungi, and centipedes. The evolution of [[vascular plants]] (''[[Cooksonia]]'') allowed plants to gain a foothold on land. These early plants were the forerunners of all plant life on land. During this time, there were four continents: Gondwana (Africa, South America, Australia, Antarctica, Siberia), Laurentia (North America), Baltica (Northern Europe), and Avalonia (Western Europe). The recent rise in sea levels allowed many new species to thrive in water.<ref>{{cite web |title=Silurian |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=[[University of California Museum of Paleontology]] |url=http://www.ucmp.berkeley.edu/silurian/silurian.php |access-date=2015-04-26 |archive-date=2017-06-16 |archive-url=https://web.archive.org/web/20170616141804/http://www.ucmp.berkeley.edu/silurian/silurian.php |url-status=live }}</ref>

=== Devonian Period ===
{{main|Devonian }}

[[File:Eogyrinus BW.jpg|thumb|[[Eogyrinus]] (an amphibian) of the Carboniferous]]
The Devonian spanned from 419–359&nbsp;million years ago. Also known as "The Age of the Fish", the Devonian featured a huge diversification of fish, including armored fish like ''[[Dunkleosteus]]'' and lobe-finned fish which eventually evolved into the first tetrapods. On land, plant groups diversified rapidly in an event known as the [[Devonian explosion]] when plants made [[lignin]], leading to taller growth and vascular tissue; the first trees and seeds evolved. These new habitats led to greater arthropod diversification. The first amphibians appeared and fish occupied the top of the food chain. Earth's second Phanerozoic mass extinction event (a group of several smaller extinction events), the [[Late Devonian extinction]], ended 70% of existing species.{{efn|name=only-counting-Phanerozoic-extinctions-note}}<ref>{{cite web |title=Devonian |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=[[University of California Museum of Paleontology]] |url=http://www.ucmp.berkeley.edu/devonian/devonian.php |access-date=2015-04-26 |archive-date=2012-05-11 |archive-url=https://web.archive.org/web/20120511155551/http://www.ucmp.berkeley.edu/devonian/devonian.php |url-status=live }}</ref>

=== Carboniferous Period ===
{{main|Carboniferous}}

The Carboniferous is named after the large coal deposits laid down during the period. It spanned from 359–299&nbsp;million years ago. During this time, average global temperatures were exceedingly high; the early Carboniferous averaged at about 20&nbsp;degrees Celsius (but cooled to 10&nbsp;°C during the Middle Carboniferous).<ref>{{cite web |author=Hieb, Monte |title=Carboniferous Era |website=geocraft.com |url=http://www.geocraft.com/WVFossils/Carboniferous_climate.html |access-date=2015-04-26 |archive-date=2014-12-20 |archive-url=https://web.archive.org/web/20141220004649/http://www.geocraft.com/WVFossils/Carboniferous_climate.html |url-status=live }}</ref> An important evolutionary development of the time was the evolution of [[Amniote|amniotic eggs]], which allowed amphibians to move farther inland and remain the dominant vertebrates for the duration of this period. Also, the first reptiles and [[synapsid]]s evolved in the swamps. Throughout the Carboniferous, there was a cooling trend, which led to the Permo-Carboniferous glaciation or the [[Carboniferous Rainforest Collapse]]. [[Gondwana]] was glaciated as much of it was situated around the south pole.<ref>{{cite web |title=Carboniferous |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=University of California Museum of Paleontology |url=http://www.ucmp.berkeley.edu/carboniferous/carboniferous.php |access-date=2015-04-26 |archive-date=2012-02-10 |archive-url=https://web.archive.org/web/20120210070913/http://www.ucmp.berkeley.edu/carboniferous/carboniferous.php |url-status=live }}</ref>

=== Permian Period ===
{{main|Permian}}
[[File:Dimetrodon grandis in "high walk" pose.png|thumb|Synapsid: ''[[Dimetrodon|Dimetrodon grandis]]'']]
The Permian spanned from 299–252&nbsp;million years ago and was the last period of the Paleozoic Era. At the beginning of this period, all continents joined together to form the supercontinent Pangaea, which was encircled by one ocean called [[Panthalassa]]. The land mass was very dry during this time, with harsh seasons, as the climate of the interior of Pangaea was not regulated by large bodies of water. [[Diapsid]]s and [[synapsid]]s flourished in the new dry climate. Creatures such as ''[[Dimetrodon]]'' and ''[[Edaphosaurus]]'' ruled the new continent. The first conifers evolved, and dominated the terrestrial landscape. Near the end of the Permian, however, Pangaea grew drier. The interior was desert, and new taxa such as ''[[Scutosaurus]]'' and [[Gorgonopsia|Gorgonopsids]] filled it. Eventually they disappeared, along with 95% of all life on Earth, in a cataclysm known as "[[Permian–Triassic extinction event|The Great Dying]]", the third and most severe Phanerozoic mass extinction.{{efn|name=only-counting-Phanerozoic-extinctions-note}}<ref>{{cite web |title=The Great Dying |website=www.nhm.ac.uk |place=London, UK |publisher=[[Natural History Museum, London|Natural History Museum]] |url=http://www.nhm.ac.uk/nature-online/life/dinosaurs-other-extinct-creatures/mass-extinctions/end-permian-mass-extinction/ |access-date= |archive-date=2015-04-20 |archive-url=https://web.archive.org/web/20150420192109/http://www.nhm.ac.uk/nature-online/life/dinosaurs-other-extinct-creatures/mass-extinctions/end-permian-mass-extinction/ |url-status=dead}}</ref><ref>{{cite web |title=Permian Era |website=www.ucmp.berkeley.edu |place=Berkeley, CA |publisher=[[University of California Museum of Paleontology]] |url=http://www.ucmp.berkeley.edu/permian/permian.php |access-date=2015-05-24 |archive-date=2017-07-04 |archive-url=https://web.archive.org/web/20170704140229/http://www.ucmp.berkeley.edu/permian/permian.php |url-status=live }}</ref>