The Earth Through Time, 8e

Eighth Edition
by Harold L. Levin


Chapter 15 - page 1

Cenozoic Events

Pamela J. W. Gore
Georgia Perimeter College


Introduction

Cenozoic Era = 65.5 million years ago to the present.

Name "Cenozoic" = "new life" or "recent life"

The Cenozoic Era followed the extinction of the dinosaurs (and many other organisms). Cenozoic rocks contain modern types of plants and animals, more advanced than those in the Paleozoic and Mesozoic. The Cenozoic is the time of the adaptive radiation of the mammals, a dramatic cooling of the Earth's climate resulting in the Ice Ages, and the evolution of humans.

The Cenozoic Era consists of two periods, the older Paleogene Period and the younger Neogene Period.

The Paris Basin is the type area for most of the epochs of the Cenozoic. There is a major unconformity in the basin, and it is chosen as the boundary between the Paleogene and the Neogene.

Until 2003, the two periods in the Cenozoic Era were the Tertiary and Quaternary Periods. You may see these terms on maps and in other publications, particularly older ones.

In 2003, the International Commission on Stratigraphy revised the nomenclature, dropping the terms Tertiary and Quaternary. The two periods of the Cenozoic Era are officially recognized as the Paleogene and the Neogene.

The Paleogene Period is divided into three epochs, Paleocene, Eocene, and Oligocene.

The Neogene Period is divided into the Miocene, Pliocene, Pleistocene, and Holocene epochs.

Era Period Epoch Millions of years
Cenozoic Neogene Holocene
0.01
Pleistocene


1.8

Pliocene


5.3

Miocene


23.0

Paleogene Oligocene


33.9

Eocene


55.8

Paleocene


65.5

Some of these epochs were proposed by Lyell in 1832 on the basis of proportions of species of fossil marine invertebrates, found in rocks of that time, that are still living. For example, only 3% of the Eocene organisms found as fossils are still living, whereas 17% of Miocene organisms found as fossils are still alive, and 50-67% of the Pliocene fossils are still living.

The meanings of the root words for the epochs of the Cenozoic are in the table below. They refer to the proportions of fossil species that are still alive.

Pleist = most

Pleion = more

Meion = less

Oligos = few

Eos = dawn

Paleo = ancient


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Document created by: Pamela J. W. Gore
Georgia Perimeter College, Clarkston, GA

February 12, 2006