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Jurassic
Large dinosaurs were dominant during the Jurassic Period. The Jurassic was named by Alexandre Brongniart for the extensive marine limestone exposures of the Jura Mountains, in the region where Germany, France and Switzerland meet.
DivisionsThe Jurassic period of time is usually broken into Early, Middle, and Late Jurassic subdivisions, also known as Lias, Dogger and Malm in europe.[1] The corresponding terms for the rocks are Lower, Middle, and Upper Jurassic. The faunal stages from youngest to oldest are:
Paleogeography
Jurassic limestones and marls (the Matmor Formation) in southern Israel. The Jurassic geological record is good in western Europe, where extensive marine sequences indicate a time when much of the continent was submerged under shallow tropical seas; famous locales include the Jurassic Coast World Heritage Site and the renowned late Jurassic lagerstätten of Holzmaden and Solnhofen.[3] In contrast, the North American Jurassic record is the poorest of the Mesozoic, with few outcrops at the surface.[4] Though the epicontinental Sundance Sea left marine deposits in parts of the northern plains of the United States and Canada during the late Jurassic, most exposed sediments from this period are continental, such as the alluvial deposits of the Morrison Formation. The Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, and invertebrate faunas with dominantly calcitic skeletons (Stanley and Hardie, 1998, 1999). The first of several massive batholiths were emplaced in the northern Cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny.[5] Important Jurassic exposures are also found in Russia, India, South America, Japan, Australasia, and the United Kingdom. Fauna
Ichthyosaurus from Liassic oil slates in Holzmaden, southern Germany. 
Gigandipus, a dinosaur footprint in the Lower Jurassic Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern Utah. Aquatic and marineDuring the Jurassic, the primary vertebrates living in the seas were fish and marine reptiles. The latter include ichthyosaurs, plesiosaurs and marine crocodiles, of the families Teleosauridae and Metriorhynchidae. In the invertebrate world, several new groups appeared, including rudists (a reef-forming variety of bivalves) and belemnites. The Jurassic also had diverse encrusting and boring (sclerobiont) communities (see Taylor & Wilson, 2003), and it saw a significant rise in the bioerosion of carbonate shells and hardgrounds. Especially common is the ichnogenus (trace fossil) Gastrochaenolites. During the Jurassic period about four or five of the twelve clades of planktonic organisms that exist in the fossil record either experienced a massive evolutionary radiation or appeared for the first time.[6] TerrestrialOn land, large archosaurian reptiles remained dominant. The Jurassic was the golden age of the large herbivorous dinosaurs known as the sauropods — Camarasaurus, Apatosaurus, Diplodocus, Brachiosaurus, and many others—that roamed the land late in the period; their mainstays were either the prairies of ferns, palm-like cycads and bennettitales, or the higher coniferous growth, according to their adaptations. They were preyed upon by large theropods as for example Ceratosaurus, Megalosaurus, Torvosaurus and Allosaurus. All these belong to the 'lizard hipped' or saurischian branch of the dinosaurs. During the Late Jurassic, the first birds evolved from small coelurosaurian dinosaurs. Ornithischian dinosaurs were less predominant than saurischian dinosaurs, although some like stegosaurs and small ornithopods played important roles as small and medium-to-large (but not sauropod-sized) herbivores. In the air, pterosaurs were common; they ruled the skies, filling many ecological roles now taken by birds. Flora
Conifers were common in the Jurassic period. In the oceans modern coral red algae appeared for the first time.[16] NotesReferences
External links
ar:??? ?????? ast:Xurásicu br:Juraseg bg:??? (??????) ca:Juràssic cs:Jura da:Jura (geologi) de:Jura (Geologie) et:Juura (geoloogia) el:???????? ???????? es:Jurásico eo:?urasio eu:Jurasiko fr:Jurassique gl:Xurásico ko:??? hr:Jura (period) id:Jura (periode) is:Júra it:Giurassico he:???? (????????) ka:?????? ??????? kk:??? ?????? la:Aevum Iurassicum lb:Jura (Geologie) lt:Jura hu:Jura (id?szak) nl:Jura (periode) ja:???? no:Jura (geologi) nn:Juratida pl:Jura pt:Jurássico ro:Jurasic ru:?????? ?????? simple:Jurassic sk:Jura (geochronologická jednotka) sl:Jura sr:???? sh:Jura (period) fi:Jurakausi sv:Jura (period) th:??????????? vi:K? Jura tr:Jura Devri uk:??????? ?????? zh:??? Source: Wikipedia | The above article is available under the GNU FDL. | Edit this article
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