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The Devonian
Devonian
is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya.[9] It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish
Fish
reached substantial diversity during this time, leading the Devonian
Devonian
to often be dubbed the "Age of Fish". The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating almost every known aquatic environment. The ancestors of all four-limbed vertebrates (tetrapods) began adapting to walking on land, as their strong pectoral and pelvic fins gradually evolved into legs.[10] In the oceans, primitive sharks became more numerous than in the Silurian
Silurian
and Late Ordovician. The first ammonites, species of molluscs, appeared. Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction
Late Devonian extinction
which started about 375 million years ago[11] severely affected marine life, killing off all placodermi, and all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana
Gondwana
to the south, the continent of Siberia to the north, and the early formation of the small continent of Euramerica
Euramerica
in between.

Contents

1 History 2 Subdivisions 3 Climate 4 Paleogeography 5 Life

5.1 Marine biota 5.2 Reefs 5.3 Terrestrial biota

5.3.1 The greening of land 5.3.2 Animals and the first soils

6 Late Devonian
Late Devonian
extinction 7 See also 8 References 9 External links

History[edit]

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The rocks of Lummaton Quarry in Torquay
Torquay
in Devon
Devon
played an early role in defining the Devonian
Devonian
period.

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 distributed throughout the county was eventually resolved by the definition of the Devonian
Devonian
period in the geological timescale. The Great Devonian Controversy was a long period of vigorous argument and counter-argument between the main protagonists of Roderick Murchison
Roderick Murchison
with Adam Sedgwick
Adam Sedgwick
against Henry De la Beche supported by George Bellas Greenough. Murchison and Sedgwick won the debate and named the period they proposed as the Devonian System.[12][13][14] While the rock beds 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 (Ogg, 2004), the Devonian
Devonian
extends from the end of the Silurian
Silurian
419.2 Mya, to the beginning of the Carboniferous
Carboniferous
358.9 Mya (in North America, the beginning of the Mississippian subperiod of the Carboniferous).[9] In nineteenth-century texts the Devonian
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
Old Red Sandstone
in which early fossil discoveries were found. Another common term is "Age of the Fishes",[15] 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.[16] The Devonian
Devonian
has also erroneously been characterized as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator
Equator
as part of the supercontinent of Euramerica
Euramerica
where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid but in fact the climate in the Devonian
Devonian
differed greatly during its 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
South America
had a warm temperate climate. In the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common.[citation needed] Subdivisions[edit] The Devonian
Devonian
Period is formally broken into Early, Middle and Late subdivisions. The rocks corresponding to those epochs are referred to as belonging to the Lower, Middle and Upper parts of the Devonian System.

Early Devonian

The Early Devonian
Early Devonian
lasted from 419.2 ± 2.8 to 393.3 ± 2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ± 2.8 to 407.6 ± 2.5, and was followed by the Emsian, which lasted until the Middle Devonian
Middle Devonian
began, 393.3± 2.7 million years ago.[citation needed]

Middle Devonian

The Middle Devonian
Middle Devonian
comprised two subdivisions: first the Eifelian, which then gave way to the Givetian 387.7± 2.7 million years ago. During this time the jawless agnathan fishes began to decline in diversity in freshwater and marine environments partly due to drastic environmental changes and partly due to the increasing competition, predation and diversity of jawed fishes. The shallow, warm, oxygen-depleted waters of Devonian
Devonian
inland lakes, surrounded by primitive plants, provided the environment necessary for certain early fish to develop such essential characteristics as well developed lungs, and the ability to crawl out of the water and onto the land for short periods of time.[citation needed]

Late Devonian

Finally, the Late Devonian
Late Devonian
started with the Frasnian, 382.7 ± 2.8 to 372.2 ± 2.5, during which the first forests took shape on land. The first tetrapods appeared in the fossil record in the ensuing Famennian subdivision, the beginning and end of which are marked with extinction events. This lasted until the end of the Devonian, 358.9± 2.5 million years ago.[citation needed] Climate[edit] The Devonian
Devonian
was a relatively warm period, and probably lacked any glaciers. The temperature gradient from the equator to the poles was not as large as it is today. The weather was also very arid, mostly along the equator where it was the driest.[17] Reconstruction of tropical sea surface temperature from conodont apatite implies an average value of 30 °C (86 °F) in the Early Devonian.[17] CO2 levels dropped steeply throughout the Devonian
Devonian
period as the burial of the newly evolved forests drew carbon out of the atmosphere into sediments; this may be reflected by a Mid- Devonian
Devonian
cooling of around 5 °C (9 °F).[17] The Late Devonian
Late Devonian
warmed to levels equivalent to the Early Devonian; while there is no corresponding increase in CO2 concentrations, continental weathering increases (as predicted by warmer temperatures); further, a range of evidence, such as plant distribution, points to a Late Devonian
Late Devonian
warming.[17] The climate would have affected the dominant organisms in reefs; microbes would have been the main reef-forming organisms in warm periods, with corals and stromatoporoid sponges taking the dominant role in cooler times. The warming at the end of the Devonian
Devonian
may even have contributed to the extinction of the stromatoporoids. Paleogeography[edit]

The Paleo-Tethys Ocean
Paleo-Tethys Ocean
opened during the Devonian

The Devonian
Devonian
period was a time of great tectonic activity, as Euramerica
Euramerica
and Gondwana
Gondwana
drew closer together. The continent Euramerica
Euramerica
(or Laurussia) was created in the early Devonian
Devonian
by the collision of Laurentia
Laurentia
and Baltica, which rotated into the natural dry zone along the Tropic of Capricorn, which is formed as much in Paleozoic
Paleozoic
times as nowadays by the convergence of two great air-masses, the Hadley cell
Hadley cell
and the Ferrel cell. In these near-deserts, the Old Red Sandstone
Old Red Sandstone
sedimentary beds formed, made red by the oxidized iron (hematite) characteristic of drought conditions.[18] Near the equator, the plate of Euramerica
Euramerica
and Gondwana
Gondwana
were starting to meet, beginning the early stages of the assembling of Pangaea. This activity further raised the northern Appalachian Mountains
Appalachian Mountains
and formed the Caledonian Mountains in Great Britain
Great Britain
and Scandinavia. The west coast of Devonian
Devonian
North America, by contrast, was a passive margin with deep silty embayments, river deltas and estuaries, found today in Idaho
Idaho
and Nevada; an approaching volcanic island arc reached the steep slope of the continental shelf in Late Devonian
Late Devonian
times and began to uplift deep water deposits, a collision that was the prelude to the mountain-building episode at the beginning of the Carboniferous called the Antler orogeny.[19] Sea levels were high worldwide, and much of the land lay under shallow seas, where tropical reef organisms lived. The deep, enormous Panthalassa
Panthalassa
(the "universal ocean") covered the rest of the planet. Other minor oceans were the Paleo-Tethys Ocean, Proto-Tethys Ocean, Rheic Ocean, and Ural Ocean (which was closed during the collision with Siberia and Baltica). Life[edit] Marine biota[edit]

Spindle diagram for the evolution of fish and other vertebrate classes. The diagram is based on Michael Benton, 2005.[20]

See also: Evolution of fish § Devonian: Age of fishes Sea levels in the Devonian
Devonian
were generally high. Marine faunas continued to be dominated by bryozoa, diverse and abundant brachiopods, the enigmatic hederellids, microconchids and corals. Lily-like crinoids (animals, their resemblance to flowers notwithstanding) were abundant, and trilobites were still fairly common. Among vertebrates, jaw-less armored fish (ostracoderms) declined in diversity, while the jawed fish (gnathostomes) simultaneously increased in both the sea and fresh water. Armored placoderms were numerous during the lower stages of the Devonian Period and became extinct in the Late Devonian, perhaps because of competition for food against the other fish species. Early cartilaginous (Chondrichthyes) and bony fishes (Osteichthyes) also become diverse and played a large role within the Devonian
Devonian
seas. The first abundant genus of shark, Cladoselache, appeared in the oceans during the Devonian
Devonian
Period. The great diversity of fish around at the time has led to the Devonian
Devonian
being given the name "The Age of Fish" in popular culture. The first ammonites also appeared during or slightly before the early Devonian
Devonian
Period around 400 Mya.[21] Reefs[edit] A now dry barrier reef, located in present-day Kimberley Basin of northwest Australia, once extended a thousand kilometers, fringing a Devonian
Devonian
continent. Reefs
Reefs
in general are built by various carbonate-secreting organisms that have the ability to erect wave-resistant frameworks close to sea level. The main contributors of the Devonian
Devonian
reefs were unlike modern reefs, which are constructed mainly by corals and calcareous algae. They were composed of calcareous algae and coral-like stromatoporoids, and tabulate and rugose corals, in that order of importance.[clarification needed]

Dunkleosteus, one of the largest armoured fish ever to roam the planet, lived during the late Devonian

Early shark Cladoselache, several lobe-finned fishes, including Eusthenopteron
Eusthenopteron
that was an early marine tetrapod, and the placoderm Bothriolepis
Bothriolepis
in a painting from 1905

Enrolled phacopid trilobite from the Devonian
Devonian
of Ohio

The common tabulate coral Aulopora
Aulopora
from the Middle Devonian
Middle Devonian
of Ohio – view of colony encrusting a brachiopod valve

Tropidoleptus carinatus, an orthid brachiopod from the Middle Devonian of New York.

Pleurodictyum
Pleurodictyum
americanum, Kashong Shale, Middle Devonian
Middle Devonian
of New York

SEM image of a hederelloid from the Devonian
Devonian
of Michigan (largest tube diameter is 0.75 mm)

Devonian
Devonian
spiriferid brachiopod from Ohio
Ohio
which served as a host substrate for a colony of hederelloids

Terrestrial biota[edit] By the Devonian
Devonian
Period, life was well underway in its colonization of the land. The moss forests and bacterial and algal mats of the Silurian
Silurian
were joined early in the period by primitive rooted plants that created the first stable soils and harbored arthropods like mites, scorpions, trigonotarbids[22] and myriapods (although arthropods appeared on land much earlier than in the Early Devonian[23] and the existence of fossils such as Climactichnites suggest that land arthropods may have appeared as early as the Cambrian). Also the first possible fossils of insects appeared around 416 Mya in the Early Devonian. Evidence for the earliest tetrapods takes the form of trace fossils in shallow lagoon environments within a marine carbonate platform/shelf during the Middle Devonian[24], although these traces have been questioned and an interpretation as fish feeding traces (Piscichnus) has been advanced.[25]

The greening of land[edit]

The Devonian
Devonian
period marks the beginning of extensive land colonization by plants. With large land-dwelling herbivores not yet present, large forests grew and shaped the landscape.

Many Early Devonian
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
Drepanophycus
likely spread by vegetative growth and spores.[26] The earliest land plants such as Cooksonia consisted of leafless, dichotomous axes and terminal sporangia and were generally very short-statured, and grew hardly more than a few centimeters tall.[27] By far the largest land organism during this period was the enigmatic Prototaxites, which was possibly the fruiting body of an enormous fungus,[28] rolled liverwort mat,[29] or another organism of uncertain affinities[30] that stood more than 8 meters tall, and towered over the low, carpet-like vegetation. By the Middle Devonian, shrub-like forests of primitive plants existed: lycophytes, horsetails, ferns, and progymnosperms had evolved. Most of these plants had true roots and leaves, and many were quite tall. The earliest known trees, from the genus Wattieza, appeared in the Late Devonian
Devonian
around 385 Mya.[31] In the Late Devonian, the tree-like ancestral Progymnosperm
Progymnosperm
Archaeopteris
Archaeopteris
which had conifer-like true wood and fern-like foliage and the cladoxylopsids grew.[32] (See also: lignin.) These are the oldest known trees of the world's first forests. By the end of the Devonian, the first seed-forming plants had appeared. This rapid appearance of so many plant groups and growth forms has been called the " Devonian
Devonian
Explosion". The 'greening' of the continents acted as a carbon sink, and atmospheric concentrations of carbon dioxide may have dropped. This may have cooled the climate and led to a massive extinction event. See Late Devonian
Late Devonian
extinction. Animals and the first soils[edit] 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
Late Devonian
period. 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 vertebrates to seek out a terrestrial living. By the end of the Devonian, arthropods were solidly established on the land.[33] Late Devonian
Late Devonian
extinction[edit] Main article: Late Devonian
Late Devonian
extinction

The Late Devonian
Late Devonian
is characterised by three episodes of extinction ("Late D")

A major extinction occurred at the beginning of the last phase of the Devonian
Devonian
period, the Famennian faunal stage (the Frasnian-Famennian boundary), about 372.2 Mya, when all the fossil agnathan fishes, save for the psammosteid heterostraci, suddenly disappeared. A second strong pulse closed the Devonian
Devonian
period. The Late Devonian
Late Devonian
extinction was one of five major extinction events in the history of the Earth's biota, and was more drastic than the familiar extinction event that closed the Cretaceous. The Devonian
Devonian
extinction crisis primarily affected the marine community, and selectively affected shallow warm-water organisms rather than cool-water organisms. The most important group to be affected by this extinction event were the reef-builders of the great Devonian
Devonian
reef-systems. Amongst the severely affected marine groups were the brachiopods, trilobites, ammonites, conodonts, and acritarchs, as well as jawless fish, and all placoderms. Land plants as well as freshwater species, such as our tetrapod ancestors, were relatively unaffected by the Late Devonian
Devonian
extinction event (but see [34] for a counterargument that the Devonian
Devonian
extinctions nearly wiped out the tetrapods). The reasons for the Late Devonian
Late Devonian
extinctions are still unknown, and all explanations remain speculative.[35] Canadian paleontologist Digby McLaren suggested in 1969 that the Devonian
Devonian
extinction events were caused by an asteroid impact. However, while there were Late Devonian collision events (see the Alamo bolide impact), little evidence supports the existence of a large enough Devonian
Devonian
crater. See also[edit]

Category: Devonian
Devonian
plants Falls of the Ohio
Ohio
State Park USA, Indiana. One of the largest exposed Devonian
Devonian
fossil beds in the world. Geologic time scale List of Early Devonian
Early Devonian
land plants List of fossil sites
List of fossil sites
(with link directory) Phacops rana: a Devonian
Devonian
trilobite.

References[edit]

^ Image:Sauerstoffgehalt-1000mj.svg ^ File:OxygenLevel-1000ma.svg ^ Image: Phanerozoic
Phanerozoic
Carbon Dioxide.png ^ Image:All palaeotemps.png ^ Haq, B. U.; Schutter, SR (2008). "A Chronology of Paleozoic Sea-Level Changes". Science. 322 (5898): 64–68. Bibcode:2008Sci...322...64H. doi:10.1126/science.1161648. PMID 18832639.  ^ Parry, S. F.; Noble, S. R.; Crowley, Q. G.; Wellman, C. H. (2011). "A high-precision U–Pb age constraint on the Rhynie Chert Konservat-Lagerstätte: time scale and other implications". Journal of the Geological Society. London: Geological Society. 168 (4): 863–872. doi:10.1144/0016-76492010-043.  ^ Kaufmann, B.; Trapp, E.; Mezger, K. (2004). "The numerical age of the Upper Frasnian (Upper Devonian) Kellwasser horizons: A new U-Pb zircon date from Steinbruch Schmidt(Kellerwald, Germany)". The Journal of Geology. 112 (4): 495–501. Bibcode:2004JG....112..495K. doi:10.1086/421077.  ^ Algeo, T. J. (1998). "Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events". Philosophical Transactions of the Royal Society B: Biological Sciences. 353 (1365): 113–130. doi:10.1098/rstb.1998.0195.  ^ a b Gradstein, Felix M.; Ogg, J. G.; Smith, A. G. (2004). A Geologic Time Scale 2004. Cambridge: Cambridge University Press. ISBN 0521786738.  ^ Amos, Jonathan. " Fossil
Fossil
tracks record 'oldest land-walkers'". news.bbc.co.uk. BBC News. Retrieved 24 December 2016.  ^ Newitz, Annalee. "How Do You Have a Mass Extinction Without an Increase in Extinctions?". The Atlantic.  ^ Rudwick M.S.J. 1985 The great Devonian
Devonian
controversy: the shaping of scientific knowledge among gentlemanly specialists. Chicago: University of Chicago Press. ^ Note:

Sedgwick and Murchison coined the term " Devonian
Devonian
system" in: Adam Sedgwick and Roderick Impey Murchison (1840) "On the physical structure of Devonshire, and on the subdivisions and geological relations of its older stratified deposits, etc.," Transactions of the Geological Society of London, 2nd series, 5 (part II) : 633-687 (Part I) and 688-705 (Part II). From p. 701: "We propose therefore, for the future, to designate these groups collectively by the name Devonian
Devonian
system, … ." Sedgwick and Murchison acknowledged William Lonsdale's role in proposing, on the basis of fossil evidence, the existence of a Devonian
Devonian
stratum between those of the Silurian
Silurian
and Carboniferous periods. From (Sedgwick and Murchison, 1840), p. 690: "Again, Mr. 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
Carboniferous
and Silurian
Silurian
systems, … ." William Lonsdale stated that in December 1837 he had suggested the existence of a stratum between the Silurian
Silurian
and Carboniferous
Carboniferous
ones. See: William Lonsdale (1840) "Notes on the age of limestones from south Devonshire," Transactions of the Geological Society of London, 2nd series, 5 (part II) : 721-738 ; see especially pp. 724 and 727. From p. 724: " … Mr. Austen's communication [was] read December 1837, … . 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. Murchison and then to Prof. Sedgwick, … ."

^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. Cambridge University Press. ISBN 9780521786737.  ^ Age of Fishes Museum ^ Barclay, W.J. 1989. Geology of the South Wales Coalfield Pt II, the country around Abergavenny, 3rd edn. Memoir of the British Geological Survey Sheet 232 (Eng & Wales) pp18-19 ^ a b c d Joachimski, M. M.; Breisig, S.; Buggisch, W. F.; Talent, J. A.; Mawson, R.; Gereke, M.; Morrow, J. R.; Day, J.; Weddige, K. (2009). " Devonian
Devonian
climate and reef evolution: Insights from oxygen isotopes in apatite". Earth and Planetary Science Letters. 284 (3–4): 599–609. Bibcode:2009E&PSL.284..599J. doi:10.1016/j.epsl.2009.05.028.  - Graph of palaeotemperature from Conodont
Conodont
apatite ^ " Devonian
Devonian
Period geochronology". Encyclopedia Britannica. Retrieved 2017-12-15.  ^ Devonian
Devonian
Paleogeography ^ Benton, M. J. (2005) Vertebrate
Vertebrate
Palaeontology John Wiley, 3rd edition, page 14. ISBN 9781405144490. ^ Palaeos Paleozoic: Devonian: The Devonian
Devonian
Period - 2 ^ Garwood, Russell J.; Dunlop, Jason (July 2014). "The walking dead: Blender as a tool for paleontologists with a case study on extinct arachnids". Journal of Paleontology. Paleontological Society. 88 (4): 735–746. doi:10.1666/13-088. ISSN 0022-3360. Retrieved 2015-07-21.  ^ Garwood, Russell J.; Edgecombe, Gregory D. (September 2011). "Early Terrestrial Animals, Evolution, and Uncertainty". Evolution: Education and Outreach. New York: Springer Science+Business Media. 4 (3): 489–501. doi:10.1007/s12052-011-0357-y. ISSN 1936-6426. Retrieved 2015-07-21.  ^ Niedźwiedzki (2010). " Tetrapod
Tetrapod
trackways from the early Middle Devonian
Devonian
period of Poland". Nature. 463 (7277): 43–48. Bibcode:2010Natur.463...43N. doi:10.1038/nature08623. PMID 20054388.  ^ Lucas (2015). "Thinopus and a Critical Review of Devonian
Devonian
Tetrapod Footprints". Ichnos. 22 (3–4): 136–154. doi:10.1080/10420940.2015.1063491.  ^ Zhang, Ying-ying; Xue, Jin-Zhuang; Liu, Le; Wang, De-ming (2016). "Periodicity of reproductive growth in lycopsids: An example from the Upper Devonian
Devonian
of Zhejiang Province, China". Paleoworld. 25 (1): 12–20. doi:10.1016/j.palwor.2015.07.002.  ^ Gonez, Paul; Gerrienne, Philippe (2010). "A new definition and a lectotypification of the genus Cooksonia Lang 1937". International Journal of Plant
Plant
Sciences. 171 (2): 199–215. doi:10.1086/648988.  ^ Hueber, Francis M. (2001). "Rotted wood-alga fungus: The history and life of Prototaxites
Prototaxites
Dawson 1859". Review of Palaeobotany and Palynology. 116: 123–159. doi:10.1016/s0034-6667(01)00058-6.  ^ Graham, Linda E.; Cook, Martha E; Hanson, David T.; Pigg, Kathleen B.; Graham, James M. (2010). "Rolled liverwort mats explain major Prototaxites
Prototaxites
features: Response to commentaries". American Journal of Botany. 97 (7): 1079–1086. doi:10.3732/ajb.1000172. PMID 21616860.  ^ Taylor, Thomas N.; Taylor, Edith L.; Decombeix, Anne-Laure; Schwendemann, Andrew; Serbet, Rudolph; Escapa, Ignacio; Krings, Michael (2010). "The enigmatic Devonian
Devonian
fossil Prototaxites
Prototaxites
is not a rolled-up liverwort mat: Comment on the paper by Graham et al.(AJB 97: 268–275)". American Journal of Botany. 97 (7): 1074–1078. doi:10.3732/ajb.1000047. PMID 21616859.  ^ Smith, Lewis (April 19, 2007). " Fossil
Fossil
from a forest that gave Earth its breath of fresh air". The Times. London. Retrieved May 1, 2010.  ^ C.Michael Hogan. 2010. Fern. Encyclopedia of Earth. eds. Saikat Basu and C.Cleveland. National Council for Science and the Environment. Washington DC. ^ Gess, R.W. (2013). "The earliest record of terrestrial animals in Gondwana: A scorpion from the Famennian (Late Devonian) Witpoort Formation of South Africa". African Invertebrates. 54 (2): 373–379. doi:10.5733/afin.054.0206.  ^ McGhee, George R. (2013). When the Invasion of Land Failed. New York: Columbia University Press. ^ Citation needed

General

Ogg, Jim; June, 2004, Overview of Global Boundary Stratotype Sections and Points (GSSP's) https://web.archive.org/web/20060716071827/http://www.stratigraphy.org/gssp.htm Accessed April 30, 2006. Palaeos Age of Fishes Museum

External links[edit]

Wikisource has original works on the topic: Paleozoic#Devonian

Wikimedia Commons has media related to Devonian.

The Devonian
Devonian
times - an excellent and frequently updated resource focussing on the Devonian
Devonian
period UC Berkeley site introduces the Devonian. " International Commission on Stratigraphy (ICS)". Geologic Time Scale 2004. Retrieved September 19, 2005.  Examples of Devonian
Devonian
Fossils

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(251.902–259.8 Mya) Guadalupian
Guadalupian
(259.8–272.3 Mya) Cisuralian
Cisuralian
(272.3–298.9 Mya)

Carboniferous
Carboniferous
(298.9–358.9 Mya)

Pennsylvanian (298.9–323.2 Mya) Mississippian (323.2–358.9 Mya)

Devonian
Devonian
(358.9–419.2 Mya)

Late (358.9–382.7 Mya) Middle (382.7–393.3 Mya) Early (393.3–419.2 Mya)

Silurian
Silurian
(419.2–443.8 Mya)

Pridoli (419.2–423.0 Mya) Ludlow (423.0–427.4 Mya) Wenlock (427.4–433.4 Mya) Llandovery (433.4–443.8 Mya)

Ordovician
Ordovician
(443.8–485.4 Mya)

Late (443.8–458.4 Mya) Middle (458.4–470.0 Mya) Early (470.0–485.4 Mya)

Cambrian
Cambrian
(485.4–541.0 Mya)

Furongian (485.4–497 Mya) Series 3 (497–509 Mya) Series 2 (509–521 Mya) Terreneuvian
Terreneuvian
(521–541.0 Mya)

Proterozoic
Proterozoic
eon² (541.0 Mya–2.5 Gya)

Neoproterozoic era (541.0 Mya–1 Gya)

Ediacaran
Ediacaran
(541.0-~635 Mya) Cryogenian (~635-~720 Mya) Tonian (~720 Mya-1 Gya)

Mesoproterozoic era (1–1.6 Gya)

Stenian (1-1.2 Gya) Ectasian (1.2-1.4 Gya) Calymmian (1.4-1.6 Gya)

Paleoproterozoic era (1.6–2.5 Gya)

Statherian (1.6-1.8 Gya) Orosirian
Orosirian
(1.8-2.05 Gya) Rhyacian (2.05-2.3 Gya) Siderian
Siderian
(2.3-2.5 Gya)

Archean
Archean
eon² (2.5–4 Gya)

Eras

Neoarchean (2.5–2.8 Gya) Mesoarchean (2.8–3.2 Gya) Paleoarchean
Paleoarchean
(3.2–3.6 Gya) Eoarchean
Eoarchean
(3.6–4 Gya)

Hadean
Hadean
eon² (4–4.6 Gya)

 

 

kya = thousands years ago. Mya = millions years ago. Gya = billions years ago.¹ = Phanerozoic
Phanerozoic
eon. ² = Precambrian
Precambrian
supereon. Source: (2017/02). International Commission on Stratigraphy. Retrieved 13 July 2015. Divisions of Geologic Time—Major Chronostratigraphic and Geochronologic Units USGS Retrieved 10 March 2013.

Authority control

GND: 40119

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