Question

Discuss the selective pressures operating in the late Miocene, Pliocene, and Pleistocene that favored the adaptive radiation of monkeys and contributed to decreased diversity among apes.

Name and describe, in your own words, the three hypotheses of primate origins.

400 words！

Answer 1

Selective pressures operating in late Pliocene, Miocene, Pleistocene that favored adaptive radiation of monkeys as well as contributed to reduced diversity among apes:

1. Plate Tectonic Motions of the Great African Rift. A chain of islands was created as a result along with East-Central Africa. These chains of islands were volcanic mountain chains.

2. Weather and climate patterns changed locally. Areas became wetter or more drier by the rain shadow phenomenon.

3. The global climate pattern was progressive cooling. Ice caps were continuously forming in the Polar Regions with the freezing of water from the seas. This attributed to the fall in sea level. Coastal lands, which were submerged underwater, were again exposed.

4. The result of above factors, Eurasia and Africa got rejoined. Continental Drift play important role.

5. The Mediterranean sea route gave migration path for the primates of Eurasia and Africa as they were rejoined.

6. Tropical forests provide the way to sparse, dry grasslands and woodlands.

Hypotheses of primate origin:                                       

1. Arboreal Theory: This theory tells that primates developed from their ancestors. They adapt some traits and habits like use of developed feet and hands for the purposes of holding, crawling and grasping to take food from tree easily.

2. Prosimian Theory: Placental mammals evolved in Eocene Epoch. They have larger bodies, bigger brains and appear in fossil records. Lemurs, Lorises and Tartiars are characteristic species of the Prosimian placental mammals.

3. Oligocene Epoch Theory: Origin of monkeys happened during the Oligocene Epoch. They were mainly forest dwellers and ate fruits and seeds. They had fewer teeth and lesser snout.