Portal:Paleozoic

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The Paleozoic Portal

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Introduction

The Paleozoic (or Palaeozoic) Era ( /ˌpæl.i.əˈz.ɪk, -i.-, ˌp.li.ə-, -li.-/ pal-ee-ə-ZOH-ik, -⁠ee-oh-, pay-lee-, -⁠lee-oh-; from the Greek palaiós (παλαιός), "old" and zōḗ (ζωή), "life", meaning "ancient life") is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the 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 comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.

The Paleozoic was a time of dramatic geological, climatic, and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, molluscs, fish, amphibians, synapsids 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 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 Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover. Recovery of life in the sea may have been much faster. ( Full article...)

Selected article on the Paleozoic world and its legacies

Modern Halobacteria sp.
The Archaea ( /ɑːrˈkə/ ( About this sound listen) or /ɑːrˈkə/; singular archaeon) constitute a domain or kingdom of single-celled microorganisms. These microbes are prokaryotes, meaning that they have no cell nucleus or any other membrane-bound organelles within their cells.

The Archaea show many differences in their biochemistry from other forms of life, and so they are now classified as a separate domain in the three-domain system. So far, the Archaea have been further divided into four recognized phyla. Classification is still difficult, because the vast majority have never been studied in the laboratory.

Archaea and bacteria are quite similar in size and shape, but despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes. Other aspects of archaean biochemistry are unique, such as their reliance on ether lipids in their cell membranes. Archaea use a much greater variety of sources of energy than eukaryotes: ranging from familiar organic compounds such as sugars, to ammonia, metal ions or even hydrogen gas. Salt-tolerant archaea use sunlight as an energy source, and other species of archaea fix carbon. Archaea reproduce asexually by binary fission, fragmentation, or budding.

Archaea are found in a broad range of habitats, including soils, oceans, marshlands and the human colon and navel. Archaea are now recognized as a major part of Earth's life and may play roles in both the carbon cycle and the nitrogen cycle. ( see more...)

Selected article on the Paleozoic in human science, culture and economics

Geologic map of the US state of Georgia.
The geologic map of Georgia (a state within the United States) is a special-purpose map made to show geological features. Rock units or geologic strata are shown by colors or symbols to indicate where they are exposed at the surface. Structural features such as faults and shear zones are also shown. Since the first national geological map, in 1809, there have been numerous maps which included the geology of Georgia. The first Georgia specific geologic map was created in 1825. The most recent state-produced geologic map of Georgia, by the Georgia Department of Natural Resources is 1:500,000 scale, and was created in 1976 by the department's Georgia Geological Survey. It was generated from a base map produced by the United States Geological Survey. The state geologist and Director of the Geological Survey of Georgia was Sam M. Pickering, Jr. Since 1976, several geological maps of Georgia, featuring the state's five distinct geologic regions, have been produced by the federal government. ( see more...)

Selected image

Laelaps by Charles R. Knight.

Illustration of Asteroxylon mackiei from the Rhynie Chert.
Photo credit: Smith609

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Restoration of the nanictopid Purlovia maxima.

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Topics

Geochronology - Cambrian ( Early - Middle - Late) - Ordovician ( Early - Middle - Late) - Silurian ( Early - Wenlock - Ludlow - Late) - Devonian ( Early - Middle - Late) - Carboniferous ( Mississippian - Pennsylvanian)- Permian ( Early - Middle - Late)

Paleozoic landmasses - Pannotia - Baltica - Laurentia - Siberia - Avalonia - Gondwanaland - Laurentia - Euramerica - Gondwana - South China- Pangaea

Major Paleozoic events - Cambrian Explosion - Cambrian substrate revolution - End-Botomian mass extinction - Cambrian–Ordovician extinction event

Cambrian biota appearances - Brachiopods - Burgess shale fauna - Cephalopods - Chitons - Crustaceans - Echinoderms - Foraminiferans - Graptolites - Radiolarians - Trilobites - Vertebrates

Ordovician biota appearances - Conodonts - Echinoids

Silurian biota appearances - Fungi - Galeaspids - Heterostracans - Land plants - Pituriaspids - Ray-finned fishes - Scorpions - Trigonotarbids

Devonian biota appearances - Crabs - Ferns - Harvestmen - Lichens - Lycophytes - Mites - Springtails - Stoneworts - Trimerophytes

Carboniferous biota appearances - Amphibians - Hagfishes - Insects - Ratfishes - Reptiles - Synapsids

Permian biota appearances - Beetles - Pelycosaurs - Temnospondyls - Therapsids

Fossil sites - Bear Gulch Limestone - Beecher's Trilobite Bed - Gilboa Forest - Grenfell fossil site - Hamilton Quarry - Mazon Creek fossil beds - Mississippi Petrified Forest - Walcott Quarry - Walcott–Rust quarry - Yea Flora Fossil Site

Stratigraphic units - Burgess Shale - Chazy Formation - Columbus Limestone - Fezouata formation - Francis Creek Shale - Gogo Formation - Holston Formation - Hunsrück Slate - Jeffersonville Limestone - Karoo Supergroup - Keyser Formation - Kope Formation - Llewellyn Formation - Mahantango Formation - Maotianshan Shales - Marcellus Formation - Millstone Grit - New Albany Shale - Old Port Formation - Old Red Sandstone - Potsdam Sandstone - Red Beds of Texas and Oklahoma - Rhynie chert - Shawangunk Formation - St. Peter Sandstone - Tuscarora Formation

History - History of paleontology - Timeline of paleontology - The Great Devonian Controversy

Researchers - Charles Emerson Beecher - Ermine Cowles Case - Edward Drinker Cope - Henry De la Beche - Stephen Jay Gould - Increase A. Lapham - Charles Lapworth - Simon Conway Morris - Roderick Murchison - Alfred Sherwood Romer - Neil Shubin - Charles Doolittle Walcott

Culture - Animal Armageddon - The Day The Earth Nearly Died - List of creatures in the Walking with... series - Lost Worlds, Vanished Lives - Miracle Planet - Prehistoric Park - Sea Monsters - Treatise on Invertebrate Paleontology - Vertebrate Paleontology - Walking with Monsters - Wonderful Life

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