Portal:Cenozoic

Topics Culture Geography Health History Mathematics Nature People Philosophy Religion Society Technology The Cenozoic Portal edit   Introduction The Cenozoic Era (/sɛnɵˈzoʊɪk/ or /ˌsiːnɵˈzoʊɪk/; also Cænozoic, Caenozoic or Cainozoic; meaning "new life", from Greek καινός kainos "new", and ζωή zoe "life") is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and covering the period from 66 million years ago to the present. The era began 65 million years ago. The Cenozoic is also known as the Age of Mammals, because the extinction of many groups allowed mammals to greatly diversify. Early in the Cenozoic, following the K-Pg event, the planet was dominated by relatively small fauna, including small mammals, birds, reptiles, and amphibians. From a geological perspective, it did not take long for mammals and birds to greatly diversify in the absence of the large reptiles that had dominated during the Mesozoic. Some birds grew larger than the average human. This group became known as the "terror birds," and were formidable predators. Mammals came to occupy almost every available niche (both marine and terrestrial), and some also grew very large, attaining sizes not seen in most of today's mammals. Climate-wise, the Earth had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, and partially offset by the Paleocene-Eocene Thermal Maximum. The continents also began looking roughly familiar at this time and moved into their current positions. edit   Selected article on the Cenozoic world and its legacies The flatworms, or Platyhelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates, (having no body cavity), and no specialized circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both the ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. Over half of all known flatworm species are parasitic. Free-living flatworms are mostly predators, and live in water or in shaded, humid terrestrial environments such as leaf litter. Analyses since the mid-1980s have separated out one subgroup, the Acoelomorpha, as basal bilaterians (animals with bilateral symmetry and hence with distinct front and rear ends). The remaining Platyhelminthes form a monophyletic group - one that contains all and only descendants of a common ancestor that is itself a member of the group. The redefined Platyhelminthes is part of the Lophotrochozoa, one of the three main groups of more complex bilaterians. These analyses had concluded the redefined Platyhelminthes, excluding Acoelomorpha, consists of two monophyletic subgroups, Catenulida and Rhabditida, with Cestoda, Trematoda and Monogenea forming a monophyletic subgroup within one branch of the Rhabditophora. Hence, the traditional platyhelminth subgroup "Turbellaria" is now regarded as paraphyletic, since it excludes the wholly parasitic groups, although these are descended from one group of "turbellarians". (see more...) edit   Selected article on the Cenozoic in human science, culture and economics Evolutionary thought, the conception that species change over time, has roots in antiquity. With the beginnings of biological taxonomy in the late 17th century, a new anti-Aristotelian approach to modern science challenged traditional essentialism. Naturalists began to focus on the variability of species; the emergence of paleontology with the concept of extinction further undermined the static view of nature. In the early 19th century, Jean-Baptiste Lamarck proposed the first fully formed theory of evolution. In 1858, Charles Darwin and Alfred Russel Wallace published a new evolutionary theory that was explained in detail in Darwin's On the Origin of Species (1859). Unlike Lamarck, Darwin proposedcommon descent and a branching tree of life. The theory was based on the idea of natural selection, and it synthesized a broad range of evidence from animal husbandry, biogeography, geology, morphology, and embryology. The debate over Darwin's work led to the rapid acceptance of the general concept of evolution, but the specific mechanism he proposed, natural selection, was not widely accepted until it was revived by developments in biology that occurred during the 1920s through the 1940s. Before that time most biologists argued that other factors were responsible for evolution. The synthesis of natural selection with Mendelian genetics during the 1920s and 1930s founded the new discipline of population genetics. Throughout the 1930s and 1940s, population genetics became integrated with other biological fields, resulting in a widely applicable theory of evolution that encompassed much of biology—the modern evolutionary synthesis. (see more...) edit   Selected picture edit   Did you know? edit   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 appearances - Brachiopods - Burgess shale fauna - Cephalopods - Chitons - Crustaceans - Echinoderms - Foraminiferans - Graptolites - Radiolarians -Trilobites - Vertebrates Ordovician appearances - Conodonts - Echinoids Silurian appearances - Fungi - Galeaspids - Heterostracans - Land plants - Pituriaspids -Ray-finned fishes - Scorpions - Trigonotarbids Devonian appearances - Crabs - Ferns - Harvestmen - Lichens - Lycophytes - Mites -Springtails - Stoneworts - Trimerophytes Carboniferous appearances - Amphibians - Hagfishes - Insects - Ratfishes - Reptiles -Synapsids Permian 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 - Paleorrota - 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 edit   Quality Content Featured Paleozoic articles - Bone Sharps, Cowboys, and Thunder Lizards - Bone Wars - Edward Drinker Cope - Geology of the Capitol Reef area - Geology of the Death Valley area -Geology of the Grand Canyon area - Geology of the Zion and Kolob canyons area Good Paleozoic articles - Chitinozoan - Coal ball - Dimetrodon - History of paleontology - Evolutionary history of life - Ornatifilum - Opabinia - Paleontology- Schinderhannes - Small shelly fauna - Temnospondyli - Tiktaalik - Waptia edit   Categories ▼ Cenozoic ► Cenozoic Africa ► Cenozoic Antarctica ► Cenozoic Asia ► Cenozoic Europe ► Cenozoic North America ► Cenozoic Oceania ► Cenozoic South America ► Paleogene ► Neogene ► Quaternary ► Cenozoic geochronology ► Cenozoic events ► Cenozoic geology ► Cenozoic life ► Cenozoic paleontological sites ► Cenozoic rifts and grabens edit   Things you can do Here are some tasks awaiting attention: Stubs : Cenozoic stubs, Paleogene stubs, Neogene stubs, Quaternary stubs Current Cenozoic FACs - none currently edit   Related content Time Earth sciences Paleontology Extinct and Endangered Species Paleozoic Mesozoic Cenozoic Paleogene Neogene Quaternary edit   Associated Wikimedia What are portals? 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