1. Chapter 12: The History of Life

2. Section One: The Fossil Record
Fossils
Used to date time an organism lived
Relative dating: estimates the time during which an organism lived by comparing the placement of fossils of the organism with the placement of fossils in other layers of rock
Usually use carbon dating

3. Section Two: The Geologic Time Scale
Index fossils
Fossils of organisms that existed only during specific spans of time over large geographic areas
The shorter the life span of the organism, the closer we can date the time it was living

4. Section Two: The Geologic Time Scale
A representation of the history of the Earth
Divided into
Eras: last tens to hundreds of millions of years and consist of 2 or more periods
Periods: lasting tens of millions of years
Epochs: the smallest units that last several million years

5. Section Four: Early Single-Celled Organisms
Endosymbiotic Theory
Endosymbiosis
A relationship in which one organism lives in the body of another, and both benefit from the relationship
Suggests that chloroplasts and mitochondria were once simple prokaryotic cells that were engulfed by larger prokaryotes