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===Terrestrial biota=== [[File:Prototaxites milwaukeensis.jpg|thumb|150px|''Prototaxites milwaukeensis'', a large fungus, initially thought to be a marine alga, from the Middle Devonian of Wisconsin]] By the Devonian Period, life was well underway in its colonization of the land. The [[moss]] forests and [[bacteria]]l and algal mats of the Silurian were joined early in the period by primitive rooted plants that created the first stable [[soil]]s and harbored arthropods like [[mite]]s, [[scorpion]]s, [[Trigonotarbida|trigonotarbids]]<ref>{{cite journal |last1=Garwood |first1=Russell J. |last2=Dunlop |first2=Jason |date=July 2014 |title=The walking dead: Blender as a tool for paleontologists with a case study on extinct arachnids |url=https://www.academia.edu/7625529 |journal=[[Journal of Paleontology]] |volume=88 |issue=4 |pages=735–746 |doi=10.1666/13-088 |bibcode=2014JPal...88..735G |s2cid=131202472 |issn=0022-3360 |access-date=2015-07-21}}</ref> and [[Myriapoda|myriapods]] (although arthropods appeared on land much earlier than in the Early Devonian<ref name="Garwood">{{cite journal |last1=Garwood |first1=Russell J. |last2=Edgecombe |first2=Gregory D. |date=September 2011 |title=Early Terrestrial Animals, Evolution, and Uncertainty |journal=Evolution: Education and Outreach |volume=4 |issue=3 |pages=489–501 |doi=10.1007/s12052-011-0357-y |df=dmy-all|doi-access=free }}</ref> and the existence of fossils such as ''[[Protichnites]]'' suggest that amphibious arthropods may have appeared as early as the [[Cambrian]]). By far the largest land organism at the beginning of this period was the enigmatic ''[[Prototaxites]]'', which was possibly the fruiting body of an enormous fungus,<ref>{{cite journal |last1=Hueber |first1=Francis M. |title=Rotted wood-alga fungus: The history and life of ''Prototaxites'' Dawson 1859 |journal=Review of Palaeobotany and Palynology |year=2001 |volume=116 |issue=1–2 |pages=123–159 |doi=10.1016/s0034-6667(01)00058-6|bibcode=2001RPaPa.116..123H }}</ref> rolled liverwort mat,<ref>{{cite journal |last1=Graham |first1=Linda E. |last2=Cook |first2=Martha E. |last3=Hanson |first3=David T. |last4=Pigg |first4=Kathleen B. |last5=Graham |first5=James M. |title=Rolled liverwort mats explain major ''Prototaxites'' features: Response to commentaries |journal=American Journal of Botany |year=2010 |volume=97 |issue=7 |pages=1079–1086 |doi=10.3732/ajb.1000172 |pmid=21616860|doi-access=free |bibcode=2010AmJB...97.1079G }}</ref> or another organism of uncertain affinities<ref>{{cite journal |last1=Taylor |first1=Thomas N. |last2=Taylor |first2=Edith L. |last3=Decombeix |first3=Anne-Laure |last4=Schwendemann |first4=Andrew |last5=Serbet |first5=Rudolph |last6=Escapa |first6=Ignacio |last7=Krings |first7=Michael |title=The enigmatic Devonian fossil ''Prototaxites'' is not a rolled-up liverwort mat: Comment on the paper by Graham et al.(AJB 97: 268–275) |journal=American Journal of Botany |year=2010 |volume=97 |issue=7 |pages=1074–1078 |doi=10.3732/ajb.1000047 |pmid=21616859|doi-access=free |bibcode=2010AmJB...97.1074T |hdl=11336/97957 |hdl-access=free }}</ref> that stood more than {{convert|8|metres|feet}} tall, and towered over the low, carpet-like vegetation during the early part of the Devonian. Also, the first possible fossils of [[insect]]s appeared around 416 Ma, in the Early Devonian. Evidence for the earliest [[tetrapod]]s takes the form of trace fossils in shallow lagoon environments within a marine carbonate platform/shelf during the Middle Devonian,<ref>{{cite journal |last1=Niedźwiedzki |year=2010 |title=Tetrapod trackways from the early middle Devonian period of Poland |journal=[[Nature (journal)|Nature]] |volume=463 |issue=7277 |pages=43–48 |doi=10.1038/nature08623 |bibcode=2010Natur.463...43N |pmid=20054388|s2cid=4428903 }}</ref> although these traces have been questioned and an interpretation as fish feeding traces (''[[Piscichnus]]'') has been advanced.<ref>{{cite journal |last1=Lucas |year=2015 |title=Thinopus and a Critical Review of Devonian Tetrapod Footprints |journal=[[Ichnos (journal)|Ichnos]] |volume=22 |issue=3–4 |pages=136–154 |doi=10.1080/10420940.2015.1063491|bibcode=2015Ichno..22..136L |s2cid=130053031 }}</ref> ====The greening of land==== {{main|Devonian explosion}} [[File:Devonianscene-green.jpg|thumb|The Devonian Period marks the beginning of extensive land colonization by [[plant]]s. With large land-dwelling [[herbivore]]s not yet present, large forests grew and shaped the landscape.]] Many [[List of Early Devonian land plants|Early Devonian plants]] did not have true roots or leaves like extant plants, although vascular tissue is observed in many of those plants. Some of the early land plants such as ''[[Drepanophycus]]'' likely spread by vegetative growth and spores.<ref>{{cite journal |last1=Zhang |first1=Ying-ying |last2=Xue |first2=Jin-Zhuang |last3=Liu |first3=Le |last4=Wang |first4=De-ming |title=Periodicity of reproductive growth in lycopsids: An example from the Upper Devonian of Zhejiang Province, China |journal=Paleoworld |year=2016 |volume=25 |issue=1 |pages=12–20 |doi=10.1016/j.palwor.2015.07.002}}</ref> The earliest land plants such as ''[[Cooksonia]]'' consisted of leafless, [[Dichotomous branching|dichotomous]] axes with terminal sporangia and were generally very short-statured, and grew hardly more than a few centimetres tall.<ref>{{cite journal |last1=Gonez |first1=Paul |last2=Gerrienne |first2=Philippe |title=A new definition and a lectotypification of the genus ''Cooksonia'' Lang 1937 |journal=International Journal of Plant Sciences |year=2010 |volume=171 |issue=2 |pages=199–215 |doi=10.1086/648988|bibcode=2010IJPlS.171..199G |s2cid=84956576 }}</ref> Fossils of ''[[Armoricaphyton|Armoricaphyton chateaupannense]]'', about 400 million years old, represent the oldest known plants with [[wood]]y tissue.<ref name="Chateau">{{cite web | url=https://www.lightsource.ca/news/details/analyzing_the_worlds_oldest_woody_plant_fossil.html | title=Analyzing the World's Oldest Woody Plant Fossil | publisher=[[Canadian Light Source]] | date=28 August 2019 | access-date=19 May 2021 | last=MacPherson | first=C. | archive-date=14 April 2021 | archive-url=https://web.archive.org/web/20210414132810/https://www.lightsource.ca/news/details/analyzing_the_worlds_oldest_woody_plant_fossil.html | url-status=dead }}</ref> By the Middle Devonian, shrub-like forests of primitive plants existed: [[Lycopodiophyta|lycophytes]], [[Equisetales|horsetails]], [[fern]]s, and [[progymnosperm]]s evolved. Most of these plants had true roots and leaves, and many were quite tall. The earliest-known trees appeared in the Middle Devonian.<ref>{{cite news |url=http://www.timesonline.co.uk/tol/news/uk/science/article1674051.ece |archive-url=https://web.archive.org/web/20080704130342/http://timesonline.co.uk/tol/news/uk/science/article1674051.ece |url-status=dead |archive-date=4 July 2008 |newspaper=The Times |location=London |title=Fossil from a forest that gave Earth its breath of fresh air |first=Lewis |last=Smith |date=April 19, 2007 |access-date=May 1, 2010 |df=dmy-all}}</ref> These included a lineage of lycopods and another arborescent, woody vascular plant, the [[Cladoxylopsida|cladoxylopsids]] and progymnosperm ''[[Archaeopteris]]''.<ref>{{cite encyclopedia |first1=C. Michael |last1=Hogan |date=2010 |url=http://www.eoearth.org/article/Fern?topic=49480 |title=Fern |encyclopedia=Encyclopedia of Earth |editor-first1=Saikat |editor-last1=Basu |editor-first2=C. |editor-last2=Cleveland |publisher=National Council for Science and the Environment |location=Washington DC}}</ref> These [[tracheophyte]]s were able to grow to large size on dry land because they had evolved the ability to biosynthesize [[lignin]], which gave them physical rigidity and improved the effectiveness of their vascular system while giving them resistance to pathogens and herbivores.<ref>{{cite journal |last1=Weng |first1=Jing-Ke |last2=Chapple |first2=Clint |title=The origin and evolution of lignin biosynthesis: Tansley review |journal=New Phytologist |date=July 2010 |volume=187 |issue=2 |pages=273–285 |doi=10.1111/j.1469-8137.2010.03327.x|pmid=20642725 |doi-access=free }}</ref> In [[Eifelian]] age, cladoxylopsid trees formed the first forests in Earth history.<ref>{{cite journal|author=Davies, Neil S., McMahon, William J. and Berry, Christopher M.|year=2024|url=https://orca.cardiff.ac.uk/id/eprint/166971/1/davies-et-al-2024-earth-s-earliest-forest-fossilized-trees-and-vegetation-induced-sedimentary-structures-from-the.pdf|title=Earth's earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England|journal=Journal of the Geological Society|volume=181 |issue=4 |doi=10.1144/jgs2023-204|bibcode=2024JGSoc.181..204D |archive-url=https://web.archive.org/web/20240309154116/https://orca.cardiff.ac.uk/id/eprint/166971/1/davies-et-al-2024-earth-s-earliest-forest-fossilized-trees-and-vegetation-induced-sedimentary-structures-from-the.pdf|archive-date=2024-03-09|url-status=live}}</ref> By the end of the Devonian, the first seed-forming plants had appeared. This rapid appearance of many plant groups and growth forms has been referred to as the Devonian Explosion or the Silurian-Devonian Terrestrial Revolution.<ref name="SilurianDevonianTerrestrialRevolution">{{cite journal |last1=Capel |first1=Elliot |last2=Cleal |first2=Christopher J. |last3=Xue |first3=Jinzhuang |last4=Monnet |first4=Claude |last5=Servais |first5=Thomas |last6=Cascales-Miñana |first6=Borja |date=August 2022 |title=The Silurian–Devonian terrestrial revolution: Diversity patterns and sampling bias of the vascular plant macrofossil record |journal=[[Earth-Science Reviews]] |volume=231 |page=104085 |doi=10.1016/j.earscirev.2022.104085 |bibcode=2022ESRv..23104085C |s2cid=249616013 |doi-access=free |hdl=20.500.12210/76731 |hdl-access=free }}</ref> The 'greening' of the continents acted as a [[carbon sink]], and [[Atmosphere of Earth|atmospheric concentrations]] of [[carbon dioxide]] may have dropped. This may have cooled the climate and led to a massive [[extinction event]]. (''See'' [[Late Devonian extinction]]). {{gallery |align=center |width=200 |height=180 |File: Lycopod axis.jpg|Lycopod axis (branch) from the Middle Devonian of Wisconsin |File: Cladoxylopsid bark.jpg|Bark (possibly from a cladoxylopsid) from the Middle Devonian of Wisconsin }} ====Animals and the first soils==== Primitive arthropods co-evolved with this diversified terrestrial vegetation structure. The evolving co-dependence of insects and seed plants that characterized a recognizably modern world had its genesis in the Late Devonian Epoch. The development of soils and plant root systems probably led to changes in the speed and pattern of [[erosion]] and sediment deposition. The rapid evolution of a terrestrial ecosystem that contained copious animals opened the way for the first [[vertebrate]]s to seek terrestrial living. By the end of the Devonian, arthropods were solidly established on the land.<ref>{{cite journal |last1=Gess |first1=R.W. |year=2013 |title=The earliest record of terrestrial animals in Gondwana: A scorpion from the Famennian (Late Devonian) Witpoort Formation of South Africa |url=http://africaninvertebrates.org/ojs/index.php/AI/article/view/284 |archive-url=https://web.archive.org/web/20130906073206/http://africaninvertebrates.org/ojs/index.php/AI/article/view/284 |url-status=usurped |archive-date=6 September 2013 |journal=[[African Invertebrates]] |volume=54 |issue=2 |pages=373–379 |doi=10.5733/afin.054.0206|bibcode=2013AfrIn..54..373G |doi-access=free }}</ref>
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