Miocene Epoch (World of Earth Science)
Notable in the development of primates and human evolution, are fossilized remains of Ardipithecus ramidus, perhaps one of the earliest identifiable ancestors of man. Fossilized remains found in Ethiopia date to approximately six million years ago, near the end of the Miocene Epoch. Importantly, the fossilized bones found provide evidence that Ardipithecus ramidus could walk upright. Anthropologists assert that the ancestral line between apes and humans diverged six to eight million years ago from a common ancestor that lived during the Miocene Epoch.
In geologic time, the Miocene Epoch occurs during the Tertiary Period (65 million years ago to 2.6 million years agond is also sometimes divided or referred to in terms of a Paleogene Period from 65 million years ago to 23 million years ago) and a Neogene Period (23 million years ago to 2.6 million years ago) instead of a singular Tertiary Periodf the Cenozoic Era of the Phanerozoic Eon. The Miocene Epoch is the fourth epoch in the Tertiary Period (in the alternative, the earliest epoch in the Neogene Period).
The Miocene Epoch ranges from approximately 23 million years ago (mya) to 5 mya. The Miocene Epoch was preceded by the Oligocene Epoch and was followed by the Pliocene Epoch.
The Miocene Epoch is further subdivided into (from earliest to most recent) Aquitanian (23 mya to 21 mya), Burdigalian (21 mya to 16 mya), Langhian (16 mya to 14 mya), Serravallian (14 mya to 10 mya), Tortonian (10 mya to 7 mya), and Messinian (7 mya to 5 mya) stages.
Craters dating to the end of the Oligocene Epoch and start of the Miocene Epoch can be studied in Northwest Canada and in Logancha, Russia. Smaller impact craters dating to the end of the middle of the Miocene Epoch are evident in Russia and Germany.
Other notable finds in the fossil record that date to the Miocene Epoch include evidence of the continued extensive development of grasslands initiated during the preceding Eocene and Oligocene Epochs. The grassland development offered a chance for grazing animals to become well established. Many of the modern migratory patterns date to the Miocene Epoch. The fusion of the Arabian plate to the Eurasian plate provided a land bridge from Africa to Asia allowing migration of species and mixing of genetic traits among reproductively compatible sub-species.
The paleobotanical record provides evidence that kelp forests also became well developed during the Miocene Epoch as the climate cyclically warmed and cooled, but more generally became less humid.
See also Archean; Cambrian Period; Cretaceous Period; Dating methods; Devonian Period; Evolution; Evolution, evidence of; Evolutionary mechanisms; Fossils and fossilization; Historical geology; Holocene Epoch; Jurassic Period; Mesozoic Era; Miocene Epoch; Mississippian Period; Ordovician Period; Paleocene Epoch; Paleozoic Era; Pennsylvanian Period; Pleistocene Epoch; Precambrian; Proterozoic Eon; Quaternary Period; Silurian Period; Triassic Period