The Pliocene Epoch
When was it?
5 to 1.8 million years ago.
What was going on?
The Australopithecines and Hominids appear.
What were the continents like?
Pretty much modern.
What kind of life existed?
Either in the terminal Miocene, or the very early Pliocene, the common ancestor of the modern
African Apes (Humans, Chimps, and Gorillas) undergoes 2 or more speciation events leading to
the three major modern species.
The earliest hominids (based on cranial fossils) appear before 4 MYA, including the possible
hominids Ardipithecus ramidus and Australopithecus anamensis; the first definitely
bipedal hominid, A. afarensis appears somewhere between 4 and 3.5 MYA and survives until
somewhere around 3 MYA; "Lucy," is a fairly complete afarensis skeleton. The relationship between
A. afarensis, and the later Australopithecines (A. africanus, and the "robust" australopithecines
A. Boisei and A. robustus aka Paranthropus boisei and P. robustus) is not clear, nor is the exact
evolutionary relationship to the earliest member of our genus. The first fossils of Homo habilis
appear around 2 million years ago, although archaeological evidence for stone tools appears somewhat
earlier, around 2.5 MYA.