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The Paleozoic
Paleozoic
(or Palaeozoic) Era ( /ˌpeɪliəˈzoʊɪk, ˌpæ-/;[1][2] from the Greek palaios (παλαιός), "old" and zoe (ζωή), "life", meaning "ancient life"[3]) is the earliest of three geologic eras of the Phanerozoic
Phanerozoic
Eon. It is the longest of the Phanerozoic
Phanerozoic
eras, lasting from 541 to 251.902 million years ago, and is subdivided into six geologic periods (from oldest to youngest): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic
Paleozoic
comes after the Neoproterozoic Era of the Proterozoic
Proterozoic
Eon and is followed by the Mesozoic
Mesozoic
Era. The Paleozoic
Paleozoic
was a time of dramatic geological, climatic, and evolutionary change. The Cambrian
Cambrian
witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian
Cambrian
explosion, in which most modern phyla first appeared. Fish, arthropods, amphibians, anapsids, synapsids, euryapsids, and diapsids all evolved during the Paleozoic. Life began in the ocean but eventually transitioned onto land, and by the late Paleozoic, it was dominated by various forms of organisms. Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe
Europe
and eastern North America. Towards the end of the era, large, sophisticated diapsids and synapsids were dominant and the first modern plants (conifers) appeared. The Paleozoic
Paleozoic
Era ended with the largest extinction event in the history of Earth, the Permian– Triassic
Triassic
extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic
Mesozoic
Era to recover.[4] Recovery of life in the sea may have been much faster.[5]

Contents

1 Geology

1.1 Periods of the Paleozoic
Paleozoic
Era

1.1.1 Cambrian
Cambrian
Period 1.1.2 Ordovician
Ordovician
Period 1.1.3 Silurian
Silurian
Period 1.1.4 Devonian
Devonian
Period 1.1.5 Carboniferous
Carboniferous
Period 1.1.6 Permian
Permian
Period

2 Tectonic activity 3 Climate 4 Flora 5 Fauna 6 See also 7 References and further reading 8 External links

Geology[edit]

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The Paleozoic
Paleozoic
era began and ended with supercontinents and in between were the rise of mountains along the continental margins, and flooding and draining of shallow seas between.[clarification needed] At its start, the supercontinent Pannotia
Pannotia
broke up. Paleoclimatic studies and evidence of glaciers indicate that central Africa was most likely in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwana
Gondwana
(510 million years ago) formed or was forming. By mid-Paleozoic, the collision of North America and Europe
Europe
produced the Acadian-Caledonian uplifts, and a subduction plate uplifted eastern Australia. By the late Paleozoic, continental collisions formed the supercontinent of Pangaea
Pangaea
and resulted in some of the great mountain chains, including the Appalachians, Ural Mountains, and mountains of Tasmania. Periods of the Paleozoic
Paleozoic
Era[edit] There are six periods in the Paleozoic
Paleozoic
Era: Cambrian, Ordovician, Silurian, Devonian, Carboniferous
Carboniferous
(alternatively subdivided into the Mississippian Period and the Pennsylvanian Period), and the Permian.[6] Cambrian
Cambrian
Period[edit] Main article: Cambrian

Trilobites

The Cambrian
Cambrian
spans from 541 million years to 485 million years and is the first period of the Paleozoic
Paleozoic
era of the Phanerozoic. The Cambrian marked a boom in evolution in an event known as the Cambrian
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
Pannotia
begins to break up, most of which later became the supercontinent Gondwana.[7] Ordovician
Ordovician
Period[edit] Main article: Ordovician

Cephalaspis
Cephalaspis
(a jawless fish)

The Ordovician
Ordovician
spanned from approximately 485 million years to approximately 443 million years ago. The Ordovician
Ordovician
was a time in Earth's history in which many of the biological classes still prevalent today evolved, such as primitive fish, cephalopods, and coral. The most common forms of life, however, were trilobites, snails and shellfish. More importantly, the first arthropods went ashore to colonize the empty continent of Gondwana. By the end of the Ordovican, Gondwana
Gondwana
was at the south pole, early North America
North America
had collided with Europe, closing the Atlantic 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
Silurian
extinction events, in which 60% of marine invertebrates and 25% of families became extinct, and is considered the first mass extinction event and the second deadliest.[8] Silurian
Silurian
Period[edit] Main article: Silurian The Silurian
Silurian
spanned from 443 to 416 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 sea scorpions, were still apex predators. 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 are the forerunners of all plant life on land. During this time, there were four continents: Gondwana
Gondwana
(Africa, South America, Australia, Antarctica, Siberia), Laurentia
Laurentia
(North America), Baltica
Baltica
(Northern Europe), and Avalonia (Western Europe). The recent rise in sea levels allowed many new species to thrive in water.[9] Devonian
Devonian
Period[edit] Main article: Devonian

Eogyrinus
Eogyrinus
(an amphibian) of the Carboniferous

The Devonian
Devonian
spanned from 416 million years to 359 million years. Also known as "The Age of the Fish", the Devonian
Devonian
featured a huge diversification of fish, including armored fish like Dunkleosteus
Dunkleosteus
and lobe-finned fish which eventually evolved into the first tetrapods. On land, plant groups diversified incredibly in an event known as the Devonian
Devonian
Explosion when plants made lignin allowing taller growth and vascular tissue: the first trees evolved, as well as seeds. This event also diversified arthropod life, by providing them new habitats. The first amphibians also evolved, and the fish were now at the top of the food chain. Near the end of the Devonian, 70% of all species became extinct in an event known as the Late Devonian
Devonian
extinction and was the second mass extinction event the world has seen.[10] Carboniferous
Carboniferous
Period[edit] Main article: Carboniferous The Carboniferous
Carboniferous
spanned from 359 million to 299 million years. During this time, average global temperatures were exceedingly high; the early Carboniferous
Carboniferous
averaged at about 20 degrees Celsius (but cooled to 10 °C during the Middle Carboniferous).[11] Tropical swamps dominated the Earth, and the lignin stiffened trees grew to greater heights and number. As the bacteria and fungi capable of eating the lignin had not yet evolved, their remains were left buried, which created much of the carbon that became the coal deposits of today (hence the name "Carboniferous"). Perhaps the most important evolutionary development of the time was the evolution of 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 synapsids evolved in the swamps. Throughout the Carboniferous, there was a cooling trend, which led to the Permo- Carboniferous
Carboniferous
glaciation or the Carboniferous
Carboniferous
Rainforest Collapse. Gondwana
Gondwana
was glaciated as much of it was situated around the south pole.[12] Permian
Permian
Period[edit] Main article: Permian

Synapsid: Dimetrodon

The Permian
Permian
spanned from 299 to 252 million years ago and was the last period of the Paleozoic
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
Pangaea
was not regulated by large bodies of water. Diapsids and synapsids flourished in the new dry climate. Creatures such as Dimetrodon
Dimetrodon
and Edaphosaurus
Edaphosaurus
ruled the new continent. The first conifers evolved, and dominated the terrestrial landscape. Near the end of the Permian, however, Pangaea
Pangaea
grew drier. The interior was desert, and new species such as Scutosaurus
Scutosaurus
and Gorgonopsids filled it. Eventually they disappeared, along with 95% of all life on Earth, in a cataclysm known as "The Great Dying", the third and most severe mass extinction.[13][14] Tectonic activity[edit] Geologically, the Paleozoic
Paleozoic
started shortly after the breakup of the supercontinent Pannotia. Throughout the early Paleozoic, that landmass was broken into a substantial number of continents. Towards the end of the era, the continents gathered together into a supercontinent called Pangaea, which included most of the Earth's land area. Climate[edit] The earliest two periods, the Ordovician
Ordovician
and Silurian, were warm greenhouse periods, with the highest sea levels of the Paleozoic (200 m above today's); the warm climate was interrupted only by a 30 million year cool period, the Early Palaeozoic Icehouse, culminating in the Huronian glaciation, 445 million years ago at the end of the Ordovican.[15] The early Cambrian
Cambrian
climate was probably moderate at first, becoming warmer over the course of the Cambrian, as the second-greatest sustained sea level rise in the Phanerozoic
Phanerozoic
got underway. However, as if to offset this trend, Gondwana
Gondwana
moved south, so that, in Ordovician time, most of West Gondwana
Gondwana
(Africa and South America) lay directly over the South Pole. The early Paleozoic
Paleozoic
climate was also strongly zonal, with the result that the "climate", in an abstract sense, became warmer, but the living space of most organisms of the time—the continental shelf marine environment—became steadily colder. However, Baltica
Baltica
(Northern Europe
Europe
and Russia) and Laurentia (eastern North America
North America
and Greenland) remained in the tropical zone, while China and Australia
Australia
lay in waters which were at least temperate. The early Paleozoic
Paleozoic
ended, rather abruptly, with the short, but apparently severe, late Ordovician
Ordovician
ice age. This cold spell caused the second-greatest mass extinction of Phanerozoic
Phanerozoic
time. Over time, the warmer weather moved into the Paleozoic
Paleozoic
Era. The middle Paleozoic
Paleozoic
was a time of considerable stability. Sea levels had dropped coincident with the ice age, but slowly recovered over the course of the Silurian
Silurian
and Devonian. The slow merger of Baltica
Baltica
and Laurentia, and the northward movement of bits and pieces of Gondwana created numerous new regions of relatively warm, shallow sea floor. As plants took hold on the continental margins, oxygen levels increased and carbon dioxide dropped, although much less dramatically. The north–south temperature gradient also seems to have moderated, or metazoan life simply became hardier, or both. At any event, the far southern continental margins of Antarctica
Antarctica
and West Gondwana
Gondwana
became increasingly less barren. The Devonian
Devonian
ended with a series of turnover pulses which killed off much of middle Paleozoic
Paleozoic
vertebrate life, without noticeably reducing species diversity overall. There are many unanswered questions about the late Paleozoic. The Mississippian (early Carboniferous
Carboniferous
Period) began with a spike in atmospheric oxygen, while carbon dioxide plummeted to new lows. This destabilized the climate and led to one, and perhaps two, ice ages during the Carboniferous. These were far more severe than the brief Late Ordovician
Ordovician
ice age; but, this time, the effects on world biota were inconsequential. By the Cisuralian
Cisuralian
Epoch, both oxygen and carbon dioxide had recovered to more normal levels. On the other hand, the assembly of Pangaea
Pangaea
created huge arid inland areas subject to temperature extremes. The Lopingian
Lopingian
Epoch is associated with falling sea levels, increased carbon dioxide and general climatic deterioration, culminating in the devastation of the Permian extinction. Flora[edit]

An artist's impression of early land plants

While macroscopic plant life appeared early in the Paleozoic
Paleozoic
Era and possibly late in the Neoproterozoic Era of the earlier eon. Plants mostly remained aquatic until sometime in the Silurian
Silurian
and Devonian Periods, about 420 million years ago, when they began to transition onto dry land. Terrestrial flora reached its climax in the Carboniferous, when towering lycopsid rainforests dominated the tropical belt of Euramerica. Climate change caused the Carboniferous Rainforest Collapse which fragmented this habitat, diminishing the diversity of plant life in the late Carboniferous
Carboniferous
and Permian.[16] Fauna[edit] A noteworthy feature of Paleozoic
Paleozoic
life is the sudden appearance of nearly all of the invertebrate animal phyla in great abundance at the beginning of the Cambrian. The first vertebrates appeared in the form of primitive fish, which greatly diversified in the Silurian
Silurian
and Devonian
Devonian
Periods. The first animals to venture onto dry land were the arthropods. Some fish had lungs, and powerful bony fins that in the late Devonian, 367.5 million years ago, allowed them to crawl onto land. The bones in their fins eventually evolved into legs and they became the first tetrapods, 390 million years ago, and began to develop lungs. Amphibians were the dominant tetrapods until the mid-Carboniferous, when climate change greatly reduced their diversity. Later, reptiles prospered and continued to increase in number and variety by the late Permian.[16] See also[edit]

Wikimedia Commons has media related to Paleozoic.

Geologic timescale Precambrian Cenozoic Mesozoic Phanerozoic
Phanerozoic
Eon

References and further reading[edit]

Wikisource has original works on the topic: Paleozoic

^ "Paleozoic". Dictionary.com Unabridged. Random House.  ^ "Paleozoic". Merriam-Webster
Merriam-Webster
Dictionary.  ^ "Paleozoic". Online Etymology Dictionary.  ^ Sahney, S. & Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time" (PDF). Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC 2596898 . PMID 18198148.  ^ http://www.economist.com/node/16524904 The Economist ^ http://www.ucmp.berkeley.edu/paleozoic/paleozoic.php ^ University of California. "Cambrian". University of California.  ^ University of California. "Ordovician". University of California.  ^ University of California. "Silurian". University of California.  ^ University of California. "Devonian". University of California.  ^ Monte Hieb. " Carboniferous
Carboniferous
Era". unknown.  ^ University of California. "Carboniferous". University of California.  ^ Natural History Museum. "The Great Dying". Natural History Museum.  ^ University of California. " Permian
Permian
Era". University of California.  ^ Munnecke, A.; Calner, M.; Harper, D. A. T.; Servais, T. (2010). " Ordovician
Ordovician
and Silurian
Silurian
sea-water chemistry, sea level, and climate: A synopsis". Palaeogeography, Palaeoclimatology, Palaeoecology. 296 (3–4): 389–413. doi:10.1016/j.palaeo.2010.08.001.  ^ a b Sahney, S.; Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology. 38 (12): 1079–1082. Bibcode:2010Geo....38.1079S. doi:10.1130/G31182.1. 

British Palaeozoic Fossils, 1975, The Natural History Museum, London. " International Commission on Stratigraphy (ICS)". Home Page. Retrieved September 19, 2005. 

v t e

Geologic history of Earth

Cenozoic
Cenozoic
era¹ (present–66.0 Mya)

Quaternary
Quaternary
(present–2.588 Mya)

Holocene
Holocene
(present–11.784 kya) Pleistocene
Pleistocene
(11.784 kya–2.588 Mya)

Neogene
Neogene
(2.588–23.03 Mya)

Pliocene
Pliocene
(2.588–5.333 Mya) Miocene
Miocene
(5.333–23.03 Mya)

Paleogene (23.03–66.0 Mya)

Oligocene
Oligocene
(23.03–33.9 Mya) Eocene
Eocene
(33.9–56.0 Mya) Paleocene
Paleocene
(56.0–66.0 Mya)

Mesozoic
Mesozoic
era¹ (66.0–251.902 Mya)

Cretaceous
Cretaceous
(66.0–145.0 Mya)

Late (66.0–100.5 Mya) Early (100.5–145.0 Mya)

Jurassic
Jurassic
(145.0–201.3 Mya)

Late (145.0–163.5 Mya) Middle (163.5–174.1 Mya) Early (174.1–201.3 Mya)

Triassic
Triassic
(201.3–251.902 Mya)

Late (201.3–237 Mya) Middle (237–247.2 Mya) Early (247.2–251.902 Mya)

Paleozoic
Paleozoic
era¹ (251.902–541.0 Mya)

Permian
Permian
(251.902–298.9 Mya)

Lopingian
Lopingian
(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.

External links[edit]

60+ images of Paleozoic
Paleozoic
Foraminifera

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