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Law of Fossil Succession

The law of fossil succession summarizes the three most important concepts in the study of fossils. The law states simply that fossils are laid down in layers according to the time they lived--the deeper scientists look, the older the fossils are that they find.

Fossils Are the Remains of Once-Living Animals
- Scientists know that a fossil represents a once-living animal. They also know that life has changed over millions of years. Knowing the succession of one type of fossilized life-form after another helps them put together a timeline of life on Earth.
Most Fossils Are from Extinct Animals
- Part of fossil succession is evolution. Scientists know that one species evolves from another, older generation and that clues to extinction might be found in the adaptations of a species' modern counterparts.
Completing the Picture
- Using the timeline of fossil succession and evolution, geologists can accurately date rocks from anywhere in the world. Over millions of years, continents have drifted apart, together, and apart again. Using fossils as guides, geologists know how old the rocks are and where they came from.

Rocks & Minerals