Index Fossil
표준화석
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<speciesfyi-glossary slug="index-fossil"></speciesfyi-glossary>Definition
A fossil of an organism that lived during a limited, well-known time period, used to date the rock in which it is found.
Detailed Explanation
Index fossils must have a short stratigraphic range (geologically brief existence), wide geographic distribution, and easy recognition. Ammonites, conodonts, and graptolites are classic index fossils for Mesozoic and Paleozoic strata. They allow geologists to correlate rock formations across continents and oceans — essential for oil exploration, geological mapping, and reconstructing ancient paleogeography.