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Middle Miocene disruption

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The term Middle Miocene disruption, alternatively the Middle Miocene extinction or Middle Miocene extinction peak, refers to a wave of extinctions of terrestrial and aquatic life forms that occurred around the middle of the Miocene Epoch, c. 14.8 to 14.5 million years ago, during the Langhian stage of the Miocene.

Researchers[citation needed] dispute the full extent of the extinctions in the middle Miocene; the most extreme estimates assert that 30% of the mammalian genera of the early Miocene epoch went extinct in the disruption — though other scientists[citation needed] rate the event much less severe. Possible causes are still speculative: the attention of some researchers[citation needed] has focused on the consequences of the bolide impact that created the Nördlinger Ries crater in southwestern Germany, which is dated in the relevant era. Volcanic action has also been considered; global volcanic ash output reached an extreme at the time, notably from the Rift Valley of East Africa,[citation needed] with consequent cooling of global climate and an advance in the East Antarctic Ice Sheet. A Middle Miocene delta 18O increase, that is a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the Southern Ocean and the South Atlantic.[1]

ReferencesEdit

  1. ^ Miller, Kenneth G.; Fairbanks, Richard G. (1983). "Evidence for Oligocene−Middle Miocene abyssal circulation changes in the western North Atlantic". Nature 306 (5940): 250–253. doi:10.1038/306250a0. 


Further readingEdit

  • Allmon, Warren D.; Bottjer, David J. (2001). Evolutionary Paleoecology: The Ecological Context of Macroevolutionary Change. New York: Columbia University Press. ISBN 0231109946. 


External linksEdit

Geological time spiral

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