The Paleozoic Era is one of the most important geological divisions of our planet"s geochronological timescale, as it marks the extensive evolution of life, along with the largest mass extinction. Read this Buzzle article to gain more information about this era on Earth, along with the respective major geological events and related facts.

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At the boundary between Ediacaran (last period of the Proterozoic Era) and Cambrian (first period of the Paleozoic Era), the Earth witnessed a sudden appearance of diversity in life. This is called the "Cambrian Explosion", as the number of new species increased dramatically within a short geological timescale.
The term "Paleozoic" has been derived from Greek words: palaios meaning "ancient" and zoe meaning "life". This era spans around 200 million years from about 542 to 252 M.A. (million years ago), and is the largest one in terms of time-span. It"s the first era of the Phanerozoic Eon, marking the beginning of life on our planet. Marine life, including reptiles, amphibians, and arthropods, evolved a lot, and consequently got introduced to the continental portions. The flora consisted of various kinds of gymnosperms, like coniferous trees and ferns, many of which are not seen in present times.The Paleozoic Era can be divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. Each has its own particular characteristics, after which they have been named. The planet experienced a lot of changes regarding widely varying parameters, like climate, biodiversity, tectonic and other geological phenomena, evolution, etc. At the end of this era, the largest mass extinction ever took place, which wiped out most of the species of plants and animals on Earth. Although the extinction occurred on a larger scale in oceanic regions, new life did not emerge on land for almost thirty million years into the next era.
The Paleozoic Era is divided into six periods, depending on various features like tectonic and geological environment, evolution of flora and fauna, climate, marine regressions and transgressions, etc. Refer to the following image to understand the timeline of this era, depending on the variation of characteristics across the periods.
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Of the 6 periods, the Cambrian, Devonian, and Carboniferous periods are of a longer duration than the others. All the periods are divided into respective stages, which vary in duration. In some timescale versions, especially in the USA, the Carboniferous period is known in the form of two separate divisions: Mississippian and Pennsylvanian, though the above chart shows a universally accepted version.
Click on the right-side forward button on the following slide-show, which will illustrate the movement of continental plates, starting from the early Proterozoic, and throughout the entire Paleozoic Era till its last period. Refresh the article to reset the slideshow.
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Middle Proterozoic
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Late Proterozoic
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Early Cambrian
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Late Cambrian
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Middle Ordovician
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Late Ordovician
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Silurian
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Early Devonian
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Late Devonian
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Mississippian
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Pennsylvanian
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Early Permian
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Late Permian
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From a geological point of view, the Earth"s surface experienced a lot of activity, including shifting of tectonic plates, formation of mountain chains, formation of coal beds, etc. At the beginning, a supercontinent called Pannotia broke up into smaller continents, thus forming several basins and small oceans between the land portions. A sudden influx of water was probably one of the main factors which led to the explosion of life at the start of the Cambrian period. At the end of Permian, all the landmasses merged again to form a supercontinent called Pangaea.Marine transgression were common, leading to the formation of numerous sedimentary deposits in basins. In the North American subcontinent, some mountain building activity took place in the form of the sediments, that formed a part of the Appalachian mountain range. In the Mississippian period, mainly marine sediments got deposited, overlain by sand, shale, and coal deposition, that belonged to the Pennsylvanian period. At the same time, the African subcontinent must have been near the polar areas, on the basis of several fossil evidences. The continent called Gondwanaland started forming slowly, and this resulted into the formation of major mountain orogenies, like Acadian and Caledonian. The Appalachian and Ural mountain ranges are a product of such couple of orogenies.After the Ice Age that occurred during Silurian, the continent called Baltica, which consisted of Russia and other northern European parts, moved to the tropical regions. Likewise, the continent of Laurentia was also characterized by tropical climate. In the middle Paleozoic, both these landmasses merged together, whereas, in the late Paleozoic, Gondwanaland merged with the other remaining continents to form a supercontinent called Pangaea.

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After extensive research and careful analysis of geological rock samples dating back to the Paleozoic Era, it has been concluded that the entire span of about 200 million years witnessed some of the greatest and most varied climate changes. Cambrian started with climatic characteristics which were more or less like the present ones. During Ordovician and Silurian, the climate became warmer, and life flourished both on land and in the oceans along with marine transgression; according to studies, this has been attributed to a phase of global warming experienced by our planet.However, conditions changed drastically as Gondwanaland moved to the polar regions, thus causing extreme glacial activities and the subsequent beginning of an Ice Age. This is believed to be the reason for the second largest mass extinction of the Phanerozoic period, when at least 60% of invertebrates in the oceans and seas became extinct. The climate became warm again during the Devonian and Carboniferous periods, and oxygen levels increased steadily. Devonian is known as the "Age of the Fish", as such climate proved to be favorable for their dominance in this time-span.Similarly, warm temperatures caused a lot of diversification in terrestrial plants, forming dense forests similar to the present rainforests. This is the reason why the period is named Carboniferous, as one of the largest and best quality of coal seams formed in this period; the reason being a large source of incompletely decomposed swamp forest wood. Carbon dioxide levels dropped further, but recovered at the end of the Carboniferous period. A drastic change in climate was present during Permian, and coupled up with marine regressions, increase in CO2 levels, etc., caused the largest mass extinction.