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 ago—and 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 Period—of the Cenozoic Era of the...