Portal:Silurian

Topics Culture Geography Health History Mathematics Nature People Philosophy Religion Society Technology The Silurian Portal The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.8 ± 1.5 million years ago (mya), to the beginning of the Devonian Period, about 419.2 ± 3.2 mya. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a major extinction event when 60% of marine species were wiped out. SeeOrdovician-Silurian extinction events. A significant evolutionary milestone during the Silurian was the appearance of jawed and bony fish. Life also began to appear on land in the form of small, moss-like, vascular plants which grew beside lakes, streams, and coastlines. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian. (See more…) Template:/box-footer Ornatifilum fossil. Ornatifilum (Latin ornatis + filum, Ornamented filament) is an artificial form genus, which is used to categorise any small, branched filaments with external ornamentation. It has been applied to microfossils of Devonian age with possible fungal affinities; two "species" have been described, and further Silurian fossils closely resemble it. These Silurian specimens hint that the organisms may have been fungal, placing them among the oldest representatives of this kingdom. (see more...) 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...) Silurian turbidites. Silurian proximal turbidite sedimentary rocks on the coast at New Quay, Ceredigion, Wales, UK. Photo credit: AliV ...that ostracoderms are the earliest known vertebrate animals? ... that fossils of the extinct bivalve family Praenuculidae have been found on every continent except Antarctica? ... that Arthropleuridea is an extinct class of myriapods which includes, at over 2 meters long, the largest terrestrial arthropods that ever lived? Template:/box-header Epochs - Llandovery - Wenlock - Ludlow - Pridoli Ages - Rhuddanian - Aeronian - Telychian - Sheinwoodian - Homerian - Gorstian - Ludfordian Events - Alice Springs Orogeny - Early Palaeozoic Icehouse - Andean-Saharan glaciation - Caledonian orogeny - Ireviken event - Lau event - Mulde event Geography - Avalonia - Baltica - Gondwana - Laurentia - Euramerica Animals - Acanthodians - Bivalves - Brachiopods - Bryozoa - Cephalopods - Crinoids - Gastropods - Hederelloids - Leeches - Tentaculitoids - Trilobites Plants - Lycopods - Rhyniophytes - Vascular plants Fossil sites - Yea Flora Fossil Site Stratigraphic units - Old Red Sandstone - Shawangunk Formation - Tuscarora Formation Researchers - Increase A. Lapham - Roderick Murchison Culture - List of creatures in the Walking with... series - Walking With Monsters Template:/box-footer Template:/box-header Featured Silurian articles - Fungus Good Silurian articles - Chitinozoan - Ornatifilum Template:/box-footer ▼ Silurian ► Silurian life Here are some tasks awaiting attention: Stubs : Silurian stubs Current Silurian FACs - none currently Template:/box-footer Time Earth sciences Paleontology Extinct and Endangered Species Paleozoic Cambrian Ordovician Silurian Error creating thumbnail: File missing Devonian Carboniferous Permian What are portals? List of portals Featured portals