faunal succession

The principle of faunal succession is based on the observation that sedimentary rock strata contain fossilised flora and fauna, and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances. A fossilised Neanderthal bone will never be found in the same stratum as a fossilised Megalosaurus, for example, because the two species lived during different geological periods, separated by many millions of years. This allows for strata to be identified and dated by the fossils found within.
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