Miocene

The specimen was found in a mountainous site known as Quebrada Honda, Bolivia, in 1978, in rock layers dated 12 million to 13 million years ago.

Going further back, it turns out we share a common ancestor with all large primates about 13 million years ago.

We learn the Pleistocene began 13 million years ago (reality 1.

So when the water of the Miocene Sea, in southern Poland, evaporated just over 13 million years ago, the salt it left behind was a treasure that eventually provided a succession of the country's kings with a third of their income in the Middle Ages.

Although they first appeared in Eurasia some 13 million years ago, the animals we know as elk first entered North America by crossing the Bering land bridge between Asia and Alaska about 120,000 years ago.

In the canyon's rocks are embedded bones of three-toed horses, oreodonts (piglike animals), camels the size of deer, pronghorn antelopes, small mastodons and rhinoceroses - animals scientists believe came to the canyon 15 million years ago to feed off native grasses that have since largely disappeared and to drink at a lake that dried up perhaps 13 million years ago.

After analyzing crystals excavated from an ancient South American streambed, researchers report in the April 10 Science that this continental connection must have taken place before 13 million years ago.

Around 5 to 13 million years ago, oceans were warmer than they are today -- even though atmospheric carbon dioxide concentrations were considerably low.

If the human and chimp mutation rates remained constant throughout evolutionary history, the species would have shared their most recent common ancestor about 13 million years ago.

He said that the result also explains the lack of fossil record for the echidna before 13 million years ago.