FORTY-FIVE

Emergent Oligocene Epoch: 34 - 23 mya

Dawn of ancestors of modern apes and humans,

but abundant fossils do not appear until  the following Miocene epoch

 

from the Greek, "few new"

The Grande Coupure was a sudden change in continuity of western European mammalian fauna, about 33.5 mya, at the Eocene-Oligocene boundary, with 17 group extinctions, and 20 first appearances

                    1) Global climate changing from wet and tropical to drier, more seasonal, and subtropical

                 

                   2) Hints of a cooling trend favors the evolution of grasses, which feed herds of grazing animals,

          

                        provide small animal and bird shelter, and stabilize the soil to reduce erosion. Unlike flowering                              

                         plants, grasses rely on wind for pollination

                   3) Increasing erosion develops in N. America and Europe, following the mountain-forming events of                          the prior Eocene epoch in those regions

                   4) In Asia, the Indian plate collides with the Eurasian plate, initiating the Himalayan mountain-                                     forming cycle

                   5) Antarctica begins ice accumulation, and becomes ice-capped, causing global, climatic cooling

                   6) Global cooling causes world-wide marine regression, with reduced marine plankton diversity;

                         many marine mammals become extinct due to climatic cooling

                   7) Late in the epoch, mammals such as horses, deer, cats, dogs, elephants, and primates dominate

                  8) Migration of land mammals continues between Asia and N. America

Features of the Oligocene epoch: 34 mya - 23 mya: