FACTOID # 24: Looking for table makers? Head to Mississippi, with an overwhlemingly large number of employees in furniture manufacturing.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Ordovician" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Ordovician
Artist impression of the Ordovician Sea.

The Ordovician period is the second of the six (seven in North America) periods[1] of the Paleozoic era, and covers the time roughly between 490 to 440 million years ago. It follows the Cambrian period and is followed by the Silurian period. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879, to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods respectively. Lapworth, recognizing that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods, realized that they should be placed in a period of their own. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. ... The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... A geologic era is a subdivision of geologic time that is a separate classification that divides the Phanerozoic Eon into three parts timeframes. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... This article is about the country. ... The Ordovices were one of the Celtic tribes living in the British Islands, before the Roman invasion of Britain. ... Charles Lapworth (September 20, 1842 – March 13, 1920) was an English geologist. ... Adam Sedgwick (March 22nd, 1785–January 27, 1873) was one of the founders of modern geology. ... Sir Roderick Murchison Sir Roderick Impey Murchison (February 19, 1792 – October 22, 1871), was an influential Scottish geologist who first described and investigated the Silurian era. ... For other uses, see Rock (disambiguation). ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... For other uses, see Fossil (disambiguation). ... Fauna is a collective term for animal life. ... For other uses, see strata (novel) and strata title. ...


While recognition of the distinct Ordovician period was slow in the United Kingdom, other areas of the world accepted it quickly. It received international sanction in 1906, when it was adopted as an official period of the Paleozoic era by the International Geological Congress. 1906 (MCMVI) was a common year starting on Monday (see link for calendar). ...

Contents

Ordovician dating

The Ordovician period started at a major extinction event called the Cambrian-Ordovician extinction events some time about 488.3 ± 1.7 million years ago (Ma) and lasted for about 44.6 million years. It ended with another major extinction event about 443.7 ± 1.5 Ma (ICS, 2004) that wiped out 60% of marine genera. A. Melott et al. (ref. 2006) suggested a ten-second gamma ray burst could have destroyed the ozone layer and exposed terrestrial and marine surface-dwelling life to deadly radiation, but most scientists agree that extinction events are complex with multiple causes. See below. The Cambrian-Ordovician extinction event occured approximately 488 million years ago, an extinction event that eliminated many brachiopods and conodonts and severely reduced the number of trilobite species. ... For other uses of mya, see mya (disambiguation). ... For other uses, see Genus (disambiguation). ... The image above shows the optical afterglow of gamma ray burst GRB-990123 taken on January 23, 1999. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ... Artist impression of the Ordovician Sea. ...


The dates given are recent radiometric dates and vary slightly from those used in other sources. This second period of the Paleozoic era created abundant fossils and in some regions, major petroleum and gas reservoirs. In telecommunication and physics, radiometry is the science of radiation measurement. ... For other uses, see Fossil (disambiguation). ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... For other uses, see Gas (disambiguation). ...


Ordovician subdivisions

The Ordovician Period is usually broken into Early (Tremadoc and Arenig), Middle (Llanvirn [subdivided into Abereiddian and Llandeilian]) and Late (Caradoc and Ashgill) epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, or Upper part of the column. The faunal stages (subdivisions of epochs) from youngest to oldest are: In geology, the Arenig group is the name applied to the lowest stage of the Ordovician System. ... In geology, Caradoc Series is the name introduced by Roderick Murchison in 1839 for the sandstone series of Caer Caradoc in Shropshire, England. ... Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ...

  • Hirnantian/Gamach (Late-Ashgill)
  • Rawtheyan/Richmond (Late-Ashgill)
  • Cautleyan/Richmond (Late-Ashgill)
  • Pusgillian/Maysville/Richmond (Late-Ashgill)
  • Trenton (Middle-Caradoc)
  • Onnian/Maysville/Eden (Middle-Caradoc)
  • Actonian/Eden (Middle-Caradoc)
  • Marshbrookian/Sherman (Middle-Caradoc)
  • Longvillian/Sherman (Middle-Caradoc)
  • Soundleyan/Kirkfield (Middle-Caradoc)
  • Harnagian/Rockland (Middle-Caradoc)
  • Costonian/Black River (Middle-Caradoc)
  • Chazy (Middle-Llandeilo)
  • Llandeilo (Middle-Llandeilo)
  • Whiterock (Middle-Llanvirn)
  • Llanvirn (Middle-Llanvirn)
  • Cassinian (Early-Arenig)
  • Arenig/Jefferson/Castleman (Early-Arenig)
  • Tremadoc/Deming/Gaconadian (Early-Tremadoc)

The Hirnantian is the seventh and final internationally-recognized stage of the Ordovician Period of the Paleozoic Era. ...

Ordovician paleogeography

Sea levels were high during the Ordovician; in fact during the Tremadocian, marine transgressions worldwide were the greatest for which evidence is preserved in the rocks. A transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in coastal flooding. ...


During the Ordovician, the southern continents were collected into a single continent called Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician, the continents Laurentia, Siberia, and Baltica were still independent continents (since the break-up of the supercontinent Pannotia earlier), but Baltica began to move towards Laurentia later in the period, causing the Iapetus Ocean to shrink between them. Also, Avalonia broke free from Gondwana and began to head north towards Laurentia. Rheic Ocean was formed as a result of this. Gondwanaland redirects here. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... This article is about the geographical term. ... For other uses, see South Pole (disambiguation). ... This article or section does not adequately cite its references or sources. ... Siberia (Sometimes called Angara) is the craton located in the heart of the region of Siberia. ... Baltica (green) Baltica is a Late Proterozoic-Early Palaeozoic continent that now includes the East European craton of northwestern Eurasia. ... In geology, a supercontinent is a land mass comprising more than one continental core, or craton. ... Pannotia is the name given to a hypothetical supercontinent that existed from about 600 to about 540 mya. ... The Iapetus Ocean was an Ocean that existed in the Southern Hemisphere between Scotland, England and Scandinavia between 400 and 600 million years ago. ... Avalonia was a paleomicrocontinent also known as a Terrane. ... The Rheic Ocean was an ocean in the Paleozoic Era that existed between the continent of Baltica (northern Europe) and number of terranes broken up from Gondwana, including the future southern Europe. ...


Ordovician rocks are chiefly sedimentary. Because of the restricted area and low elevation of solid land, which set limits to erosion, marine sediments that make up a large part of the Ordovician system consist chiefly of limestone. Shale and sandstone are less conspicuous. Two types of sedimentary rock: limey shale overlaid by limestone. ... For morphological image processing operations, see Erosion (morphology). ... This article or section cites very few or no references or sources. ... For other uses, see Limestone (disambiguation). ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ...


A major mountain-building episode was the Taconic orogeny that was well under way in Cambrian times. Illustration of the Taconic orogeny The Taconic orogeny was a great mountain building period that perhaps had the greatest overall effect on the geologic structure of basement rocks within the New York Bight region. ...


By the end of the period, Gondwana had neared or approached the pole and was largely glaciated. This article is about the geological formation. ...


Climate

The Early Ordovician climate was thought to be quite warm, at least in the tropics. As with North America and Europe, Gondwana was largely covered with shallow seas during the Ordovician. Shallow clear waters over continental shelves encouraged the growth of organisms that deposit calcium carbonates in their shells and hard parts. Panthalassic Ocean covered much of the northern hemisphere, and other minor oceans included Proto-Tethys, Paleo-Tethys, Khanty Ocean which was closed off by the Late Ordovician, Iapetus Ocean, and the new Rheic Ocean. For other uses, see Europe (disambiguation). ... The blue ocean surrounding Pangaea is Panthalassa Panthalassa (Greek for all seas) was the vast ocean that surrounded the supercontinent Pangaea during the late Paleozoic era and the early Mesozoic era. ... Proto-Tethys Ocean was an ancient ocean that existed from the latest Ediacaran to the Carboniferous. ... The Paleo-Tethys Ocean was an ancient Paleozoic ocean. ... Khanty Ocean was an ancient, small ocean that existed near the end of the Precambrian time to the Silurian. ... The Iapetus Ocean was an Ocean that existed in the Southern Hemisphere between Scotland, England and Scandinavia between 400 and 600 million years ago. ... The Rheic Ocean was an ocean in the Paleozoic Era that existed between the continent of Baltica (northern Europe) and number of terranes broken up from Gondwana, including the future southern Europe. ...


As the Ordovician progressed, we see evidence of glaciers on the land we now know as Africa and South America. At the time these land masses were sitting at the South Pole, and covered by ice caps. This article is about the geological formation. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... For other uses, see South Pole (disambiguation). ... An ice cap is a dome-shaped ice mass that covers less than 50,000 km² of land area (usually covering a highland area). ...


Ordovician Life

Ordovician bryozoa, Batavia, Ohio

Bryozoa, Ordovician limestone, Batavia, Ohio Image copyleft: Image taken by me, released under GFDL Pollinator 14:46, Aug 24, 2004 (UTC) ( ) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Bryozoa, Ordovician limestone, Batavia, Ohio Image copyleft: Image taken by me, released under GFDL Pollinator 14:46, Aug 24, 2004 (UTC) ( ) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Classes Stenolaemata Gymnolaemata Phylactolaemata Bryozoans are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ...

Ordovician fauna

Though less famous than the Cambrian explosion, the Ordovician featured an adaptive radiation that was no less remarkable; marine faunal genera increased fourfold, resulting in 12% of all known Phanerozoic marine fauna.[2] The trilobite, inarticulate brachiopod, archaeocyathid, and eocrinoid faunas of the Cambrian were succeeded by those which would dominate for the rest of the Paleozoic, such as articulate brachiopods, cephalopods, and crinoids; articulate brachiopods, in particular, largely replaced trilobites in shelf communities.[3] Their success epitomizes the greatly increased diversity of carbonate shell-secreting organisms in the Ordovician compared to the Cambrian.[4] The Cambrian explosion is the geologically kukko sudden appearance in the fossil record of the ancestors of familiar animals, starting about 542 million years ago (Mya). ... Four of the 13 finch species found on the Galápagos Archipelago, and thought to have evolved by an adaptive radiation that diversified their beak shapes to adapt them to different food sources. ... For other uses, see Genus (disambiguation). ... During the Phanerozoic the biodiversity shows a steady but not monotonic increase from near zero to several thousands of genera. ... Orders Agnostida Redlichiida Corynexochida Lichida Nektaspida? Phacopida Proetida Asaphida Harpetida Ptychopariida Trilobites are extinct arthropods in the class Trilobita. ... Classes Lingulata Paterinata (extinct) Craniforma Chileata (extinct) Obolellata (extinct) Kutorginata (extinct) Strophomenata (extinct) Rhynchonellata Brachiopods (from Latin bracchium, arm + New Latin -poda, foot) make up one of the major animal phyla, Brachiopoda. ... The Archeocyatha, also called Archaeocyathids, were sessile, reef-building marine organisms that lived during the Lower Cambrian period (500-600 million years ago). ... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Nautilida The Cephalopods (head-foot) are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusc foot into the form of arms or tentacles. ... Subclasses Articulata (540 species) Cladida (extinct) Flexibilia (extinct) Camerata (extinct) Disparida (extinct) Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). ...  Sediment  Rock  Mantle  The global continental shelf, highlighted in cyan The continental shelf is the extended perimeter of each continent, which is covered during interglacial periods such as the current epoch by relatively shallow seas (known as shelf seas) and gulfs. ... Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ...


In North America and Europe, the Ordovician was a time of shallow continental seas rich in life. Trilobites and brachiopods in particular were rich and diverse. The first bryozoa appeared in the Ordovician as did the first coral reefs. Solitary corals date back to at least the Cambrian. Molluscs, which had also appeared during the Cambrian or the Ediacaran, became common and varied, especially bivalves, gastropods, and nautiloid cephalopods. It was long thought that the first true vertebrates (fish - Ostracoderms) appeared in the Ordovician, but recent discoveries in China reveal that they probably originated in the Early Cambrian. The very first jawed fish appeared in the Late Ordovician epoch. Now-extinct marine animals called graptolites thrived in the oceans. Some cystoids and crinoids appeared. Classes Stenolaemata Gymnolaemata Phylactolaemata Bryozoans are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ... Some of the biodiversity of a coral reef, in this case the Great Barrier Reef, Australia. ... Extant Subclasses and Orders Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea [1][2]  See Anthozoa for details For other uses, see Coral (disambiguation). ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... The Ediacaran[5][6]  â€¢  â€¢  | Neoproterozoic (last æon of the Precambrian) Phanerozoic Axis scale: millions of years ago. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... Subclass Subclass Eogastropoda     Patellogastropoda Subclass Orthogastropoda   Superorder Cocculiniformia   Superorder Hot Vent Taxa     Neomphaolida   Superorder Vetigastropoda   Superorder Neritaemorphi     Neritopsina   Superorder Caenogastropoda     Architaenioglossa     Sorbeoconcha   Superorder Heterobranchia     Heterostropha     Opisthobranchia     Pulmonata The gastropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 species, and second largest class... Orders Palcephalopoda †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida Neocephalopoda (in part) †Orthocerida †Ascocerida †Bactritida Nautiloids are a group of marine mollusks in the subclass Nautiloidea, which all possess an external shell, the best-known example being the modern nautiluses. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... This article or section does not cite its references or sources. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... Classes Placodermi Chondrichthyes Acanthodii Actinopterygii Sarcopterygii Gnathostomata is the group of vertebrates with jaws. ... The Late Ordovician, also called the Upper Ordovician by geologists, is the third epoch of the Ordovician period. ... Graptolites (Graptolita) are colonial animals known chiefly from the Upper Cambrian through the Mississippian (Lower Carboniferous). ...


During the Middle Ordovician there was a large increase in the intensity and diversity of bioeroding organisms. This is known as the Ordovician Bioerosion Revolution (Wilson & Palmer, 2006). It is marked by a sudden abundance of hard substrate trace fossils such as Trypanites, Palaeosabella and Petroxestes. Bioerosion describes the erosion of hard ocean substrates by living organisms by a number of mechanisms. ...

Ordovician flora

Green algae were common in the Ordovician and Late Cambrian (perhaps earlier). Plants probably evolved from green algae. The first terrestrial plants appeared in the form of tiny non-vascular plants resembling liverworts. Fossil spores from land plants have been identified in uppermost Ordovician sediments, but among the first land fungi may have been Arbuscular mycorrhiza fungi (Glomerales), playing a crucial role in facilitating the colonization of land by plants through mycorrhizal symbiosis, which makes mineral nutrients available to plant cells; such fossilized fungal hyphae and spores from the Ordovician of Wisconsin have been found with an age of about 460 mya, a time when the land flora most likely only consisted of plants similar to non-vascular bryophytes.[5] Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... For other uses, see Plant (disambiguation). ... Orders Jungermanniopsida Metzgeriales (simple thalloids) Haplomitriales (Calobryales) Jungermanniales (leafy liverworts) Marchantiopsida Sphaerocarpales (bottle liverworts) Marchantiales (complex thalloids) Monocleales Liverworts are a division of plants commonly called hepatics, Marchantiophyta or liverworts. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... An arbuscular mycorrhiza (plural mycorrhizae or mycorrhizas) is a type of mycorrhiza in which the fungus penetrates the cortical cells of the roots of a vascular plant. ... Wikispecies has information related to: Glomerales Glomerales is an order of symbiotic fungi within the phylum Glomeromycota. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ...


Marine fungi were abundant in the Ordovician seas to decompose animal carcasses, and other wastes.[verification needed] Decomposition is the reduction of bodies and other formerly living organisms into simpler forms of matter; and most particularly to the fate of the body, after death. ... For other uses, see Animal (disambiguation). ... Carcass of a chicken after cooking Carcass may refer to: A carcass (or carcase) is a term for a dead body, typically that of an animal. ...


End of the Ordovician

Main article: Ordovician-Silurian extinction events
.

The Ordovician came to a close in a series of extinction events that, taken together, comprise the second largest of the five major extinction events in Earth's history in terms of percentage of genera that went extinct. The only larger one was the Permian-Triassic extinction event. The Ordovician-Silurian extinction event, labeled End O here. ... An extinction event (also known as: mass extinction; extinction-level event, ELE) occurs when there is a sharp decrease in the number of species in a relatively short period of time. ... The Earth, photographed from Apollo 17 in 1972. ... For other uses, see Genus (disambiguation). ...


The extinctions occurred approximately 444-447 million years ago and mark the boundary between the Ordovician and the following Silurian Period. At that time all complex multicellular organisms lived in the sea, and about 49% of genera of fauna disappeared forever; brachiopods and bryozoans were decimated, along with many of the trilobite, conodont and graptolite families. The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... Classes Lingulata Paterinata (extinct) Craniforma Chileata (extinct) Obolellata (extinct) Kutorginata (extinct) Strophomenata (extinct) Rhynchonellata Brachiopods (from Latin bracchium, arm + New Latin -poda, foot) make up one of the major animal phyla, Brachiopoda. ... Fossilized Bryozoa, Ordovician limestone, Batavia, Ohio Bryozoans (moss animals) are tiny colonial animals that generally build stony skeletons of calcium carbonate, superficially similar to coral. ... Orders Agnostida Nectaspida Redlichiida Corynexochida Lichida Phacopida Subclass: Librostoma Proetida Asaphida Harpetida Ptychopariida For the robot vacuum cleaner, see Electrolux Trilobite. ... Conodonts are extinct worm-like forms with distinctive conical or multi-denticulate teeth made of apatite (calcium phosphate). ... Graptolites (Graptolithina) are fossil colonial animals known chiefly from the Upper Cambrian through the Mississippian (Lower Carboniferous). ...


The most commonly accepted theory is that these events were triggered by the onset of an ice age, in the Hirnantian faunal stage that ended the long, stable greenhouse conditions typical of the Ordovician. The ice age was probably not as long-lasting as once thought; study of oxygen isotopes in fossil brachiopods shows that it was probably no longer than 0.5 to 1.5 million years.[6] The event was preceded by a fall in atmospheric carbon dioxide (from 7000ppm to 4400ppm) which selectively affected the shallow seas where most organisms lived. As the southern supercontinent Gondwana drifted over the South Pole, ice caps formed on it, which have been detected in Upper Ordovician rock strata of North Africa and then-adjacent northeastern South America, which were south-polar locations at the time. Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... The Royal Greenhouses of Laeken. ... Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. ... Gondwanaland redirects here. ...  Northern Africa (UN subregion)  geographic, including above North Africa or Northern Africa is the northernmost region of the African continent, separated by the Sahara from Sub-Saharan Africa. ...


Glaciation locks up water from the world-ocean, and the interglacials free it, causing sea levels repeatedly to drop and rise; the vast shallow intra-continental Ordovician seas withdrew, which eliminated many ecological niches, then returned carrying diminished founder populations lacking many whole families of organisms, then withdrew again with the next pulse of glaciation, eliminating biological diversity at each change.[7] Species limited to a single epicontinental sea on a given landmass were severely affected.[8] Tropical lifeforms were hit particularly hard in the first wave of extinction, while cool-water species were hit worst in the second pulse.[9]


Surviving species were those that coped with the changed conditions and filled the ecological niches left by the extinctions.


At the end of the second event, melting glaciers caused the sea level to rise and stabilise once more. The rebound of life's diversity with the permanent re-flooding of continental shelves at the onset of the Silurian saw increased biodiversity within the surviving Orders.


Notes

  1. ^ The Carboniferous in North America is divided in two, the Mississippian and the Pennsylvanian.
  2. ^ Dougal Dixon et al., Atlas of Life on Earth, (New York: Barnes & Noble Books, 2001), p. 87.
  3. ^ John D. Cooper, Richard H. Miller, and Jacqueline Patterson, A Trip Through Time: Principles of Historical Geology, (Columbus: Merrill Publishing Company, 1986), pp. 247, 255-9.
  4. ^ Ibid., 255-6.
  5. ^ D. Redecker, R. Kodner and L.E. Graham, "Glomalean fungi from the Ordovician" Science 2000 Sep 15;289(5486):1920-1.
  6. ^ Steven M. Stanley, Earth System History, (New York: W.H. Freeman and Company, 1999), 358.
  7. ^ Emiliani, (1992), 491
  8. ^ Stanley, 360.
  9. ^ Stanley, 360

This article is about the geologic period; for the North American culture, see Mississippian culture. ... The Pennsylvanian is an epoch of the Carboniferous period lasting from roughly 325 Ma to 299 Ma (million years ago). ...

References

  • Ogg, Jim, June, 2004, Overview of Global Boundary Stratotype Sections and Points (GSSP's) http://www.stratigraphy.org/gssp.htm Accessed April 30, 2006.
  • Stanley, Steven M., Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6
  • Mehrtens, Dr. Charlotte, "Chazy Reef at Isle La Motte". An Ordovician reef in Vermont.
  • Adrian Melott et al., "Did a gamma-ray burst initiate the late Ordovician mass extinction?" International Journal of Astrobiology 3 (2004) 55
  • BBC News, " Ray burst is extinction suspect", 11 April 2005.
  • ABC News, "Ray burst may have wiped out life on Earth", 29 April 2004
  • Wilson, M.A. and Palmer, T.J., 2001. Domiciles, not predatory borings: a simpler explanation of the holes in Ordovician shells analyzed by Kaplan and Baumiller, 2000. Palaios 16:524-525.
  • Wilson, M.A. and Palmer, T.J. 2006. Patterns and processes in the Ordovician Bioerosion Revolution. Ichnos 13: 109-112.[1]

External links

Wikimedia Commons has media related to:
Ordovician
Ordovician period
Lower/Early Ordovician Middle Ordovician Upper/Late Ordovician
Tremadocian | Stage 2 Stage 3 | Darriwilian Stage 5 | Stage 6
Hirnantian
Paleozoic era
Cambrian Ordovician Silurian Devonian Carboniferous Permian

  Results from FactBites:
 
The Ordovician (318 words)
The Ordovician period began approximately 510 million years ago, with the end of the Cambrian, and ended around 445 million years ago, with the beginning of the Silurian.
The Ordovician is best known for the presence of its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates).
From the Early to Middle Ordovician, the earth experienced a milder climate in which the weather was warm and the atmosphere contained a lot of moisture.
Ordovician (347 words)
The Ordovician Period is the second of the six (seven in North America) periods of the Paleozoic Era.
The Ordovician follows the Cambrian Period and is followed by the Silurian Period.
The Ordovician -- named for a Welsh tribe -- was defined by Charles Lapworth in 1879 to resolve a situation where followers of Adam Sedgwick and Roderick Murchison were placing the same rock beds in the Cambrian and Silurian Periods respectively.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m