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How to Find the Age Range of a Fossil

As the remains of prehistoric life, fossils can give scientists a peek into the past. The fossilized remnants of human, animal and plant life over 10,000 years old exist in sedimentary rocks. Interestingly, the rocks surrounding the fossils serve as a guide to estimate the age of the fossils and vice versa. Yet determining the age range of fossils can be challenging, especially if parts of the same fossil type are found deposited in different environments. Each dating technique has its drawbacks, so scientists use a variety of relative and absolute techniques to find the age range of fossils.

Instructions

- 1
  Use stratigraphy or superposition to study how deeply the fossil is buried. The fossil's placement in the sedimentary rock bed will help you determine its age relative to other ones. Fossils deposited in the lower layers of the sedimentary rock are older than those deposited in the upper layers ̵1; as new rock layers form above older ones, with the passage of time.
- 2
  Estimate the age of animal fossils with biostratigraphy, a technique that uses animal fossils to mark specific time periods. For instance, the age of the fossils of elephants or horses found in a layer of rock, are the same as the fossils of elephants or horses found in the same rock layer at a nearby site.
- 3
  Use radiocarbon dating to determine the age of fossils such as wood or bone younger than 50,000 years. The isotopes in these fossils have different rates of radioactive decay that remain constant -- serving as a "radiometric clock" to ascertain the absolute age of fossils.
- 4
  Determine the age range of fossils with palynology, a technique that analyzes the pollen layer in the surrounding soil. Scientists have already determined the age of the pollen layer at most fossil sites. Pollen analysis also helps in understanding the climate and environment in which the fossil existed.

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