Here's why:
* Distinctive and Easily Recognizable: Index fossils are unique and easy to identify, even for non-experts.
* Geographically Widespread: They existed over a large geographic area, which allows for comparisons across different locations.
* Short Lived: Index fossils have a relatively short geological lifespan, meaning they only existed for a specific period. This allows for more precise dating.
Trilobites, for example, existed for millions of years but within that time, different species evolved and went extinct, each with its own specific timeframe. Finding a specific trilobite species can help pinpoint the age of the rock layer containing it.
