User:Abyssal/Portal:Permian

The Permian Portal Introduction Selected article on the Permian world and its legacies Acanthodes. A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups. Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as ambient temperatures change. Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams to even hadal depths of the deepest oceans. At 32,000 species, fish exhibit greater species diversity than any other group of vertebrates. Because the term "fish" is defined negatively, and excludes the tetrapods (i.e., the amphibians, reptiles, birds and mammals) which descend from within the same ancestry, it is paraphyletic, and is not considered a proper grouping in systematic biology. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessednotochords which allowed them to be more agile than their invertebrate counterparts. Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many (such as sharks) became formidable marine predators rather than just the prey of arthropods. (see more...) Did you know? Methanosarcina barkeri fusaro. ... that the single-celled Methanosarcina (Methanosarcina barkeri fusaro pictured) may have played a significant role in both the evolution of early life and the worst extinction event in history? ... that Gerobatrachus is considered to be a missing link that supports the hypothesis offered by cladistics, that frogs and salamanders had a common ancestor? ... that Arthropleuridea is an extinct class of myriapods which includes, at over 2 meters long, the largest terrestrial arthropods that ever lived? Need help? Do you have a question about Abyssal/Portal:Permian that you can't find the answer to? Consider asking it at the Wikipedia reference desk. Selected image Cross-bedded Permian Sandstone. These are the remnants of ancient desert sand dunes from around 300 to 350 million years ago. Photo credit: Tony Atkin Selected article on the Permian in human science, culture and economics A skeletal mount of Edaphosaurus. Paleontology or palaeontology (/ˌpeɪliɒnˈtɒlədʒi, ˌpæli-, -ən-/) is the scientific study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments (their paleoecology). As a "historical science" it attempts to explain causes rather than conduct experiments to observe effects. Paleontological observations have been documented as far back as the 5th century BC. The science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, and developed rapidly in the 19th century. The term itself originates from Greek: παλαιός (palaios) meaning "old, ancient," ὄν, ὀντ- (on, ont-), meaning "being, creature" and λόγος (logos), meaning "speech, thought, study". Paleontology lies on the border between biology and geology. It now uses techniques drawn from a wide range of sciences, including biochemistry, mathematics and engineering. Use of all these techniques has enabled paleontologists to discover much of the evolutionary history of life, almost all the way back to when Earth became capable of supporting life, about 3,800 million years ago. As knowledge has increased, paleontology has developed specialized sub-divisions, some of which focus on different types of fossil organisms while others study ecology and environmental history, such as ancient climates. Body fossils and trace fossils are the principal types of evidence about ancient life, and geochemical evidence has helped to decipher the evolution of life before there were organisms large enough to leave fossils. (see more...) Geochronology Epochs - Cisuralian - Guadalupian - Lopingian Ages - Asselian - Sakmarian - Artinskian - Kungurian - Roadian - Wordian - Capitanian -Wuchiapingian - Changhsingian Events - Hunter-Bowen orogeny - Permian–Triassic extinction event Geography - Pangaea - Panthalassa Animals - Ammonoids - Blattopterans - Dicynodonts - Dinocephalians - Fusulinids - Gorgonopsians - Lepospondyls - Pareiasaurs - Pelycosaurs - Temnospondyls - Trilobites Plants - Conifers - Cycads - Ginkgos - Seed ferns Stratigraphic units - Red Beds of Texas and Oklahoma Researchers - Edward Drinker Cope Culture - Animal Armageddon - The Day The Earth Nearly Died - List of creatures in the Walking with... series - Walking with Monsters Subcategories Permian Permian Africa Permian Antarctica Permian Asia Permian Europe Permian North America Permian Oceania Permian South America Permian geochronology Permian events Permian geology Permian life Permian paleogeography Permian stubs Quality Content Featured Permian articles - Amphibian Good Permian articles - Dimetrodon - Temnospondyli Things you can do Here are some tasks awaiting attention: Stubs : Permian stubs Current Permian FACs - none currently Related content Time Earth sciences Paleontology Extinct and Endangered Species Paleozoic Cambrian Ordovician Silurian Devonian Carboniferous Permian Mesozoic Associated Wikimedia The following Wikimedia Foundation sister projects provide more on this subject: Commons Free media repository Wikibooks Free textbooks and manuals Wikidata Free knowledge base Wikinews Free-content news Wikiquote Collection of quotations Wikisource Free-content library Wikiversity Free learning tools Wiktionary Dictionary and thesaurus ¤ Category:Geologic time portals