hich isolated Western Europe from the exchange of flora and fauna, was periodically disrupted, allowing for the migration of animals. Additionally, faunal routes with Africa were well established and occasional land bridges were also created.
Africa also encountered some tectonic movement, including rifting in East Africa and the union of the African-Arabian plate with Eurasia. Associated with this rifting, a major uplift in East Africa created a rain shadow effect between the wet Central-West Africa and dry East Africa. The union of the continents of Africa and Eurasia caused interruption and contraction of the Tethys Sea, thereby depleting the primary source of atmospheric moisture in that area. Thus rainfall was significantly reduced, as were the moderating effects of sea temperature on the neighboring land climates. However, this union enabled more vigorous exchanges of flora and fauna between Africa and Eurasia.
Antarctica became isolated from the other continents in the Miocene, leading to the formation of a circumpolar ocean circulation. Global ocean and atmospheric circulation were also affected by the formation of this circumpolar circulation pattern, as it restricted north-south circulation flows. This reduced the mixing of warm, tropical ocean water and cold, polar water causing additional buildup of snow and ice on Antarctica. This accelerated the development of global seasonality, aridity, and enhanced global cooling.
This entry is based on an article written for the University of California Museum of Paleontology by Brian R. Speer, Lucy Brining, Valerie Chan, Ellen Choi, Michael De Sosa, and Christina Lee.
- Behrensmeyer, Anna K., John D. Damuth, William A. DiMichele, Richard Potts, Hans-D. Sues and Scott L. Wing (Editors). 1992. Terrestrial Ecosystems Through Time: Evolutionary Paleoecology of Terrestrial Plants and Animals. University of Chicago Press, Chicago.
- Palmer, A.R. and J. Geissman.1999. Geologic Timescale. Geological Society of America (GSA).