Portal:Devonian

Topics Culture Geography Health History Mathematics Nature People Philosophy Religion Society Technology The Devonian Portal The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 419.2 ± 3.2 Mya(million years ago), to the beginning of the Carboniferous Period, about 358.9 ± 0.4. It is named after Devon, England, where rocks from this period were first studied. The Devonian period experienced the first significant adaptive radiation of terrestrial life. Since large vertebrateterrestrial herbivores had not yet appeared, free-sporingvascular plants began to spread acrossdry 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 firstseed-bearing plants appeared. Various terrestrial arthropods also became well-established. Fish reached substantial diversity during this time, leading the 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 tetrapods began adapting to walking on land, their strong pectoral and pelvic fins gradually evolved into legs. In the oceans, primitive sharks became more numerous than in the Silurian and the late Ordovician. The firstammonite mollusks appeared.Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction severely affected marine life, killing off all placoderms, and all trilobites, save for a few species of the order Proetida. The paleogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, and the early formation of the small continent of Euramerica in between. (See more…) Template:/box-footer Tiktaalik /tɪkˈtɑːlᵻk/ is a monospecific genus of extinct sarcopterygian (lobe-finned fish) from the late Devonian period, with many features akin to those of tetrapods (four-legged animals). It is an example from several lines of ancient sarcopterygian fish developing adaptations to the oxygen-poor shallow-water habitats of its time, which led to the evolution of tetrapods. Well-preserved fossils were found in 2004 on Ellesmere Island in Nunavut, Canada.(see more...) Oil shale, also known as kerogen shale, is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil can be produced. Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact. Deposits of oil shale occur around the world. Estimates of global deposits range from 2.8 to 3.3 trillion barrels (450×10^9 to 520×10^9 m3) of recoverable oil. Heating oil shale to a sufficiently high temperature causes the chemical process of pyrolysis to yield a vapor. Upon cooling the vapor, the liquid shale oil—an unconventional oil—is separated from combustible oil-shale gas (the term shale gas can also refer to gas occurring naturally in shales). Oil shale can also be burned directly in furnaces as a low-grade fuel for power generation and district heating or used as a raw material in chemical and construction-materials processing. Oil-shale mining and processing raise a number of environmental concerns, such as land use, waste disposal, water use, waste-water management, greenhouse-gas emissions and air pollution. Estonia and China have well-established oil shale industries, and Brazil, Germany, and Russia also utilize oil shale. (see more...) Sample of the Devonian Barre Granite from E. L. Smith Quarry of the Rock of Ages Stone Company, Graniteville, Vermont. Photo credit: Jstuby ...that fossil Thelodont fish (depiction pictured) surprised scientists by showing that stomachs evolved before jaws? ... that the extinct bivalve subfamily Praenuculinae can be told apart from its sister subfamily by looking at teeth? ... that Arthropleuridea is an extinct class of myriapods which includes, at over 2 meters long, the largest terrestrial arthropods that ever lived? ...that ostracoderms are the earliest known vertebrate animals? Template:/box-header Epochs - Early Devonian - Middle Devonian - Late Devonian Ages - Lochkovian - Pragian - Emsian - Eifelian - Givetian - Frasnian - Famennian Events - Alice Springs Orogeny - Caledonian orogeny - Acadian orogeny - Karoo Ice Age Landmasses - Baltica - Laurentia - Euramerica - Gondwana Bodies of water Ural Ocean - Panthalassa Paleo-Tethys - Proto-Tethys - Rheic Ocean Animals - Ammonoids - Brachiopods - Bryozoans - Corals - Crinoids - Hederelloids - Insects - Microconchids - Ostracoderms - Placoderms - Sharks - Tetrapods - Trilobites Fungi - Prototaxites Plants - Ferns - Horsetails - Lycophytes - Progymnosperms Fossil sites - Grenfell fossil site Stratigraphic units - Columbus Limestone - Gogo Formation - Hunsrück Slate - Jeffersonville Limestone - Keyser Formation - Mahantango Formation - Marcellus Formation - New Albany Shale - Old Port Formation - Old Red Sandstone - Rhynie chert History - The Great Devonian Controversy Researchers - Henry De la Beche - Roderick Murchison - Neil Shubin Culture - Animal Armageddon - List of creatures in the Walking with... series - Miracle Planet - Sea Monsters - Walking With Monsters Template:/box-footer Template:/box-header Featured Devonian articles - None Good Devonian articles - Chitinozoan - Fish - Marcellus Formation - Ornatifilum - Schinderhannes - Tiktaalik Template:/box-footer ▼ Devonian ► Devonian life Here are some tasks awaiting attention: Stubs : Devonian stubs Current Devonian 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? 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