Introduction to the Cenozoic

65 Million Years to the Present

The Cenozoic is the most recent of the three major subdivisions of animal history. The other two are the Paleozoic and Mesozoic. The Cenozoic spans only about 65 million years, from the end of the Cretaceous and the extinction of non-avian dinosaurs to the present. The Cenozoic is sometimes called the Age of Mammals, because the largest land animals have been mammals during that time. This is a misnomer for several reasons. First, the history of mammals began long before the Cenozoic began. Second, the diversity of life during the Cenozoic is far wider than mammals. The Cenozoic could have been called the "Age of Flowering Plants" or the "Age of Insects" or the "Age of Teleost Fish" or the "Age of Birds" just as accurately.

The Cenozoic is divided into two main sub-divisions: the Tertiary and the Quaternary. Most of the Cenozoic is the Tertiary, from 65 million years ago to 1.8 million years ago. The Quaternary includes only the last 1.8 million years.

Click on the buttons below to learn more about the Cenozoic Era.

Or click on a subdivision of the
Cenozoic to visit its exhibit!

The chart at left shows the several subdivisions of the Cenozoic Era. After the column labelled "Cenozoic", the next column shows the two periods, the Tertiary and the Quaternary. The Tertiary Period is subdivided into the Paleogene and the Neogene, though we have not created exhibits for these divisions.

The right-hand column lists the six major epochs into which the periods are divided. You may click on any of these to visit our exhibit on that epoch. A separate seventh period is often recognized for the last 11,000 years, and is called the Holocene.

The Cenozoic occurs after the Mesozoic and continues to the present day.

UCMP Special Exhibit: Paleontological Institute of Russia
Take a tour of the world's largest paleo institute, including many Cenozoic mammals from Russia.

Find out more about the Cenozoic paleontology and geology of North America at the Paleontology Portal.