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Fossils are only in very rare cases dated directly, because they do not contain sufficient radioactive isotopes for dating. Most geological periods are first and foremost defined by biostratigraphy- fossil assemblages, typically. The Cambrian period starts with the Fortunian stage - this stage is defined by the appearance of a certain trace fossil in ...


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The short answer is no, because we always have some constraint of how old something is. Sometimes we have fossils with large date error bars, and often we do not know for how long that species existed. A large date range constraint in some cases, like archeology, might not be useful. If the specimen is taken without noting the location it was taken from, ...


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