User:Abyssal/Portal:Cambrian
The Cambrian PortalIntroductionThe Cambrian ( /ˈkæmbri.ən, ˈkeɪm-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 485.4 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. (Full article...) Selected natural world articleGood evidence exists for the appearance of gastropods, cephalopods and bivalves in the Cambrian period 538.8 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. (see more...) Did you know...
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Selected science, culture, and economics articleGould's most significant contribution to evolutionary biology was the theory of punctuated equilibrium, which he developed with Niles Eldredge in 1972. The theory proposes that most evolution is marked by long periods of evolutionary stability, which is punctuated by rare instances of branching evolution. The theory was contrasted against phyletic gradualism, the popular idea that evolutionary change is marked by a pattern of smooth and continuous change in the fossil record. Most of Gould's research was based on the land snail genera Poecilozonites and Cerion. He also contributed to evolutionary developmental biology, and has received wide praise for his book Ontogeny and Phylogeny. In evolutionary theory he opposed strict selectionism, sociobiology as applied to humans, and evolutionary psychology. Gould was known by the general public mainly from his 300 popular essays in the magazine Natural History, and his books written for a non-specialist audience. In April 2000, the US Library of Congress named him a "Living Legend". (see more...) TopicsEpochs - Terreneuvian - Cambrian Series 2 - Cambrian Series 3 - Furongian Geography - Pannotia - Baltica - Gondwanaland - Laurentia - Siberia Fossil sites - Walcott Quarry Researchers - Stephen Jay Gould - Simon Conway Morris - Charles Doolittle Walcott SubcategoriesQuality ContentFeatured Cambrian articles - None Things you can doRelated contentAssociated WikimediaThe following Wikimedia Foundation sister projects provide more on this subject:
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