A Brief History of Earth: Four Billion Years in Eight Chapters

by Andrew H. Knoll

Life, then, is characterized by growth and reproduction, metabolism, and evolution.

As we move backward in time, we run out of rocks to examine before we run out of evidence for life. Earth has been a biological planet for most of its long history.

In this view, the Great Oxygenation Event was not simply a product of Earth’s physical development; nor did it exclusively reflect evolutionary innovation. It was the interaction between Earth and life that transformed our planet’s surface.

For sauropods, size provided a strong defense against predators (elephants seldom fear leopards).