The story can be traced in many parts of the world. So let's go to the Yangtze gorges, or the edges of the Gobi desert, or the Atlantic coast of Newfoundland. The idea is to stroll past the rocks, through 50 million years of Earth history. A day will be plenty of time. The start is pretty discouraging.
Fossils are tiny and difficult to find.
Next we come to thick layers of what is effectively rubble, bulldozed by ancient glaciers. So widely distributed are these glacial deposits that it now appears the entire Earth was enshrouded in ice. Then an episode of global warming allowed the first animals to flourish. And what strange creatures they are. Rather rubbery in texture, they present a major evolutionary enigma, but they are the harbingers of the most spectacular evolutionary unfolding the world has ever seen.