The Late Ordovician, also called the Upper Ordovician by geologists, is the third epoch of the Ordovician period. A geologist is a contributor to the science of geology, studying the physical structure and processes of the Earth. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ...

At this time Western and Central Europe and North America collided to form Laurentia, while glaciers built up in Gondwana, which was positioned over the South Pole. This caused a drop in global temperatures, resulting in "ice house" conditions. A common understanding of Western Europe in modern times. ... Regions of Europe Central Europe is the region lying between the variously and vaguely defined areas of Eastern and Western Europe. ... World map showing North America A satellite composite image of North America. ... North American craton. ... Pangaea was formed by the merging of two continents, Laurasia and Gondwana East African and Kuungan Orogens 550 Ma reconstruction showing final stages of assembly The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America... Location of the South Pole in the Antarctic continent. ...

For most of this time life continued to flourish, but at the end of the period there was a mass-extinction that seriously affected planktonic forms like conodonts, graptolites, and some groups of trilobites (Agnostida and Pytchopariida, which compeletly died out, while the Asaphida were much reduced). Brachiopods and bryozoans and echinoderms were also heavily affected, and the endocerid nautiloids died out completely, except for possible rare Silurian forms. The two Ordovician-Silurian Extinction events, taken together were the second largest of the major extinction events that have occurred in the Earths history. ... Photomontage of plankton organisms For the Spongebob SquarePants character, see Sheldon J. Plankton. ... 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). ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida doubtful order Nektaspida Trilobites are extinct arthropods in the class Trilobita. ... Families Suborder Agnostina Superfamily Agnostoidea Agnostidae Ammagnostidae Clavagnostidae Diplagnostidae Doryagnostidae Glyptagnostidae Metagnostidae Peronopsidae Ptychagnostidae Superfamily Condylopygoidea Condylopygidae Suborder Eodiscina Superfamily Eodiscoidea Calodiscidae Eodiscidae Hebediscidae Tsunyidiscidae Weymouthiidae Yukoniidae Agnostida (the agnostids) is an order of trilobite. ... Superfamilies Anomocaroidea Asaphoidea Dikelokephaloidea Remopleuridoidea Cyclopygoidea Trinucleioidea Asaphida is a large, morphologically diverse order of trilobites that are found in strata dated from the Middle Cambrian boundary to the Upper Ordovician. ... Subphyla and classes See Classification 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. ... Classes Asteroidea Blastoidea (extinct) Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea The echinoderms (Echinodermata) are a phylum of marine animals found in the ocean at all depths. ... Orders Palcephalopoda Plectronocerida (extinct) Ellesmerocerida (extinct) Actinocerida (extinct) Endocerida (extinct) Tarphycerida (extinct) Oncocerida (extinct) Discosorida (extinct) Nautilida Neocephalopoda Orthocerida (extinct) Ascocerida (extinct) Bactritida (extinct) Nautiloids are a group of marine mollusks which all possess an external shell, the most well known example being the modern nautiluses. ...

External links

• Middle & Late Ordovician Climate
• The World during the Middle and Late Ordovician paleogeography
• The Late Ordovician
• GeoWhen Database - Late Ordovician
• The Ordovician Mass Extinction
• BBC Evolution Weekend: Extinction Files (very brief entry)