By:Daniel J. Peppe(Department of Geology, Baylor University)&Alan L. Deino(Berkeley Geochronology Center)©2013snucongo.org Education


You are watching: What must be true about an index fossil whose absolute age is used as a reference for other fossils

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Citation:Peppe,D.J.&Deino,A.L.(2013)Dating Rocks and also Fossils using Geologic Methods.snucongo.org education Knowledge4(10):1
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Using relative and radiometric dating methods, geologists room able to answer the question: just how old is this fossil?

Despite seeming prefer a reasonably stable place, the Earth"s surface ar has adjusted dramatically end the previous 4.6 exchange rate years. Mountains have been built and also eroded, continents and oceans have actually moved great distances, and the earth has fluctuated native being extremely cold and also almost completely covered v ice come being really warm and also ice-free. These alters typically take place so slowly that they are barely detectable over the expectations of a person life, yet even at this instant, the Earth"s surface is moving and also changing. As these alters have occurred, organisms have evolved, and remnants the some have been preserved as fossils.

A fossil have the right to be learned to determine what sort of organism it represents, how the organism lived, and how it to be preserved. However, by chin a fossil has actually little an interpretation unless it is placed within some context. The age of the fossil need to be established so it deserve to be compared to various other fossil species from the exact same time period. Expertise the periods of associated fossil species helps scientists piece together the evolutionary background of a team of organisms.

For example, based on the primate fossil record, scientists understand that life primates evolved from fossil primates and also that this evolutionary background took 10s of countless years. By to compare fossils of various primate species, scientists have the right to examine just how features adjusted and just how primates advanced through time. However, the period of every fossil primate requirements to be figured out so the fossils of the very same age discovered in various parts the the world and fossils of various ages have the right to be compared.

There space three basic approaches that enable scientists to date geological materials and also answer the question: "How old is this fossil?" First, the relative age of a fossil can be determined. Relative dating put geologic occasions in chronological order without requiring that a details numerical age be assigned to each event. Second, the is possible to determine the numerical age for fossils or planet materials. Numerical periods estimate the date of a geological event and also can sometimes reveal quite exactly when a fossil types existed in time. Third, magnetism in rocks can be provided to calculation the age of a fossil site. This technique uses the orientation that the Earth"s magnetic field, i m sorry has adjusted through time, come determine eras for fossils and also rocks.