The Miocene epoch extends from about 23.03 to 5.333 million years ago (Ma). The Miocene was named by Charles Lyell and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene and is followed by the Pliocene epoch.
- 2.1: Introduction to the Miocene Epoch
- Relative to the Oligocene Epoch, the Miocene was initially warmer and by the mid-Miocene, primates had once again ventured into the northern latitudes. This time they were apes, versus the prosimians of the Eocene. However, like those earlier primates, the northern apes would eventually go extinct due to global cooling that began ~14 mya.
- 2.2: Sahelanthropus tchadensis
- The Sahelanthropus tchadensis specimen (see Figure 6.2) was discovered in 2001 at the site of Toros-Menalla, in the Djurab Desert of northern Chad, by Michel Brunet and associates.
- 2.3: Orrorin tugenensis
- In 2000, the team of Brigitte Senut and Martin Pickford discovered fossil material from the Lukeino Formation in the Tugen Hills of Kenya. Nicknamed “Millenium Man” due to its timely discovery, the fossils were dated to ~6 mya and given the taxonomic classification, Orrorin tugenensis (“original man from the Tugen hills”).
- 2.4: Ardipithecus ramidus and Ardipithecus kadabba
- Deposits within the Afar triangle/depression of Ethiopia (see Figure 8.2) have yielded multiple hominin species within the genera Ardipithecus and Australopithecus. This hotbed of hominin fossils is the northern limit of the East African Rift Zone, where the Arabian and African plates converge. The first species of ardipith to be discovered in the area was Ar. ramidus (4.4 mya), and the second and even older species was Ar. kadabba (5.8 mya).
Thumbnail: Miocene fauna of North America. Mural made for the US government-owned Smithsonian Museum (Public Domain).