The Cenozoic Era is the most recent of the three major subdivisions of animal history. The other two are the Mesozoic and Paleozoic Eras. The Cenozoic spans only about 65 million years, from the end of the Cretaceous Period 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.

What is the Cenozoic Era?

-Paleogene Period (65-23 million years ago), which consists of the Paleocene, Eocene and Oligocene epochs);

-Neogene Period (23-2.6 million years ago), which includes the Miocene and Pliocene epochs)

-Quaternary Period (2.6 million years ago to the present), consisting the Pleistocene and Holocene epochs). While it is widely accepted that we are still in the Holocene Epoch, some scientists argue that we have entered the Anthropocene Epoch. In a 2010 article in the scientific journal Environmental Science & Technology, scientists made the case for a new epoch, blaming humans for causing a drastic shift in conditions.

The three periods in the Cenozoic

Statigraphy

The concepts of Tertiary and Quaternary have an interesting history. In the 1760s and 1770s a geologist named Giovanni Arduino was studying the rocks and minerals in Tuscany. He classified mountains according to the type of rocks that he found in them. Unfossil i ferous schists, granites, and basalts (all volcanic rocks) that formed the cores of large mountains he called Primitive. Fossil-rich rocks of limestone and clay that were found on the flanks of mountains over the Primitive rocks were called Secondary. Finally, there were another group of fossil i ferous rocks of limestones and sandstones lying over the Secondary rocks and forming the foothills of the mountains that Anduino called Tertiary. So at first, Tertiary referred to a certain type of rock found in the area of Tuscany. But later, geologists used the fossils found in the Tertiary rocks there to recognize rocks of the same age elsewhere. Rocks with the same species of fossils were the same age.

Facts

The Cenozoic Era is the last major division in time, beginning 65.5 million years ago and continuing until today. The three eras - the Paleozoic Era, the Mesozoic Era, and the Cenozoic Era - make up the Eras of the Phanerozoic. These three eras are broken into 12 periods. The Cenozoic Era is also referred to as the Age of Mammals as mammals began to rule the earth following the extinction of dinosaurs in the Mesozoic Era.