The Pliocene (5.2-1.64 mya)
Pliocene community (Smithsonian Institution 2000)
Climate continued
to cool and dry during the Pliocene (Prothero 1998), resulting in the domination
of evergreen over deciduous forests, and a
general decline in tree numbers (WGBH 2001). Steppe environments appeared
and replaced many of the savannas that were
created during the Miocene (Prothero 1998). By the end of the Pliocene,
ice sheets covered both the north and south poles (WGBH 2001) and the earth
had entered a period of fluctuating glacial conditions (Prothero 1998). These
glacial conditions may have been caused by changed ocean circulation patterns
resulting from the closure of the Isthmus of Panama, which connected North
and South America and divided the Atlantic and Pacific Oceans (WGBH 2001).
