For example, 60 million years is a measure of absolute time. These are numerical representations of time, and they give us specific points of reference.
We have a long record of events in absolute time but much of that occurred before humans were on Earth to write it down.
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Knowing when a dinosaur or other animal lived is important because it helps us place them on the evolutionary family tree.
Accurate dates also allow us to create sequences of evolutionary change and work out when species appeared or became extinct. These are: Where possible, several different methods are used and each method is repeated to confirm the results obtained and improve accuracy.
Tools like radiometric dating allow some samples to be assigned a certain age to within some accuracy.
But, how can we determine how old a rock formation is, if it hasn’t previously been dated?
Instead, other methods are used to work out a fossil’s age.
These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.
Before radiometric dating it was difficult to determine the actual age of an object.
Radiometric dating, based on known rates of decay of radioactive isotopes in objects, allows a specific age of an object to be determined to some degree of accuracy.