Cenozoic Era

Mammals and the Modern World

Era Age (Myrs) Epoch

0.01Holocene

1.8Pleistocene

5.3Pliocene

23.8Miocene

33.6Oligocene

54.8Eocene

65Paleocene

144

206

248

290

323

354

417

443

490

543

2500

3800

Precambrian

Phanerozoic

Eon

Proterozoic

Archean

Hadean

Period

Quaternary

Tertiary

Neogene

Paleocene

Mississippian

Cenozoic

Mesozoic

Paleozoic

Cretaceous

Jurassic

Age of the Earth 4600 Myrs (4.6 Byrs)Source: Geological Society of America (1999)

Geologic Time Scale

Devonian

Silurian

Ordivician

Cambrian

Triassic

Permian

Pennsylvanian

Cenozoic65-0 Myr

Highlights of the Cenozoic:Geology

1. Continents move into their current configurations. (Western NA remains active.)

2. Tethys Sea closes with the Alpine/Himalayan Orogeny.

3. Minor sea level fluctuations

4. Temperature peaks in the Eocene and drops through the Pliocene/Pleistocene Ice Age.

Highlights of the Cenozoic:Life

1. Mammals and angiosperms (including grasses) diversify and dominate.

2. Mammals return to the sea.

3. Two minor mass extinctions - Eocene and Pleistocene/Holocene.

4. Humans appear in the Pliocene and by the late Holocene become a “geologic force”.

Cenozoic Geology

Late Cretaceous

Early Eocene

Late Eocene

Early Miocene

Late Miocene

Separation of Antarctica

&Climate

Alpine/Himalayan Orogeny & the Closing of the Tethys Sea

Central American

Land Bridge

Climate -Hot to Cold

Sea LevelFluctuations

Transgression Regression

The Pliocene/Pleistocene Ice Age

The Final Ice Age

What Causes Ice Ages?

1. Position of the Continents• Changes to Ocean Currents• Closer o Poles

2. Orogenies / Uplift of Land Surface• Changes in air circulation• Increased erosion

3. Changes in Greenhouse Gases

Glacial Cycles within an Ice Age

What Causes Cycles?

Some Effects of the Ice

Changing Ecosystems