FORTY-SIX

Emergent Miocene: 23 - 5.3 mya

Features of the Miocene epoch 23 -5.3 mya:

5) Grasslands and savannas spread through N. America, while deserts develop later, in the Pliocene and Pleistocene epochs.

1) dated at 20-23 mya: M. Leakey discovers earliest hominoid fossil on Rusinga Island (in Lake Victoria, Kenya), in 1951: Proconsul heseloni

        a) the earliest of apes;

        b) retained some skeletal, monkey-like features of backbone, pelvis, and forelimbs;

        c) quadruped (walked on all four limbs), not a brachiator ( tree-swinger)

4) dated at 6.5 mya: Fossil of Sahelanthropus tschadensis is the first hominin discovered.

2) dated at 17 mya: early apes traversed a land bridge (due to lowered sea-levels) into Eurasia:

         a) developed thick tooth enamel, allowing diet of nuts and tough-coated seeds,                            not available to Proconsul;

         b) apes diversified into at least 8 forms.

3) dated at 13 mya: 2 lineages of early apes - 

          a) Asia: Sivapithecus migrates to S.E. Asia, ancestor of orang-utans;

          b) Europe: Dryopithecus migrates back to Africa, ancestor of African apes and

              humans.