After the dinosaurs disappeared, a new chapter of Earth history began. The Cenozoic Era started about 66 million years ago and continues to the present. It is often called the Age of Mammals because mammals diversified rapidly to fill ecological niches left vacant.

The era is divided into the Paleogene, Neogene, and Quaternary periods. Continents drifted toward their modern positions, mountain ranges such as the Alps and Himalayas rose, and global climate cooled from the warm early Cenozoic into the ice ages of the Pleistocene.

Fossils from Cenozoic rocks record the evolution of grasses, modern plant communities, and the ancestors of humans. Ice-core and sediment records from this era provide the most detailed climate history available. We are still living in the Cenozoic, specifically in the Holocene epoch of the Quaternary.

• Current geologic era beginning 66 million years ago
• Marked by mammal diversification
• Includes Paleogene, Neogene, and Quaternary
• Features major mountain building and climate cooling