Middle Miocene disruption

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.

Madelaine Bohme^[1] observed the occurrence of Varanidae, Chamaeleon, Cordylidae, Tomistomidae, Alligatoridae, and giant turtles which indicate survival through the Miocene Climatic Optimum (18 to 16 Ma) in Central Europe (42W 45 N palaeolatitude). A major and permanent cooling step occurred between 14.8 and 14.1 Ma, associated with increased production of cold Antarctic deep waters and a major growth of the East Antarctic ice sheet. Two crocodiles of the genera Gavialosuchus and Diplocynodon were noted to have been extant in these northern latitudes prior to the permanent cooling step then became extinct 13.5 to 14 Ma.

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.^[2]

References

1. ^ Madelaine Bohme, The Miocene Climatic Optimum: evidence from ectothermic vertebrates of Central Europe
2. ^ 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 reading

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

External links

• GeoWhen Database Criteria for defining the Middle Miocene in fossiliferous strata, based in part on Gradstein, Ogg, Smith, _A Geologic Time Scale, 2004.
• Middle Miocene global map

Extinction eventsv · d · e

Minor events

↓End-Ediacaran?

↓Lau event

↓Toarcian turnover

↓Aptian

↓Cenomanian-Turonian

↓Middle Miocene
    disruption

↓Cambro-Ordovician

↓Ordo-Silurian

↓Late Devonian

↓Permo-Triassic

↓Triassic–Jurassic

↓Cretaceous-Tertiary

Major events

 

Ediacaran

 

 

Cambrian

 

 

Ordovician

 

 

Silurian

 

 

Devonian

 

 

Carboniferous

 

 

Permian

 

 

Triassic

 

 

Jurassic

 

 

Cretaceous

 

 

Palæogene

 

 

Neo-
gene

 

 

Neoproterozoic

 

 

Palæozoic

 

 

Mesozoic

 

 

Cenozoic

 

 

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-50

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Millions of years before present