By:Daniel J. Peppe(Department the Geology, Baylor University)&Alan L. Deino(Berkeley Geochronology Center)©2013beer-selection.com Education


You are watching: To be useful as an index fossil, a species must have existed for a

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Citation:Peppe,D.J.&Deino,A.L.(2013)Dating Rocks and also Fossils utilizing Geologic Methods.beer-selection.com education Knowledge4(10):1
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Using relative and also radiometric date methods, geologists room able come answer the question: exactly how old is this fossil?

Despite seeming like a relatively stable place, the Earth"s surface ar has adjusted dramatically end the past 4.6 exchange rate years. Mountains have been built and eroded, continents and also oceans have moved great distances, and the planet has fluctuated indigenous being exceptionally cold and almost completely covered through ice to being really warm and ice-free. These transforms typically happen so gradually that they room barely detectable end the expectancy of a human life, yet even at this instant, the Earth"s surface is moving and also changing. Together these changes have occurred, organisms have evolved, and also remnants the some have been maintained as fossils.

A fossil have the right to be learned to recognize what sort of organism it represents, how the organism lived, and how it to be preserved. However, by chin a fossil has actually little definition unless it is put within some context. The period of the fossil need to be figured out so it can be compared to various other fossil varieties from the very same time period. Understanding the periods of associated fossil species helps scientists item together the evolutionary background of a team of organisms.

For example, based on the primate fossil record, scientists understand that life primates advanced from fossil primates and that this evolutionary background took 10s of numerous years. By comparing fossils of various primate species, scientists have the right to examine just how features readjusted and exactly how primates developed through time. However, the age of each fossil primate needs to be identified so that fossils that the exact same age found in various parts that the world and fossils of various ages can be compared.

There are three basic approaches that allow scientists to day geological materials and answer the question: "How old is this fossil?" First, the relative period of a fossil deserve to be determined. Family member dating place geologic occasions in chronological order there is no requiring the a specific numerical age be assigned to each event. Second, it is feasible to determine the numerical age for fossils or planet materials. Numerical ages estimate the day of a geology event and also can occasionally reveal quite precisely when a fossil varieties existed in time. Third, magnetism in rocks can be supplied to estimate the period of a fossil site. This method uses the orientation the the Earth"s magnetic field, i m sorry has readjusted through time, to determine ages for fossils and also rocks.