Dating ancient fossils
By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site. Though still heavily used, relative dating is now augmented by several modern dating techniques.
Radiocarbon dating involves determining the age of an ancient fossil or specimen by measuring its carbon content. Carbon, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide. As the isotopes decay, they give off particles from their nucleus and become a different isotope.
The parent isotope is the original unstable isotope, and daughter isotopes are the stable product of the decay. Half-life is the amount of time it takes for half of the parent isotopes to decay. The decay occurs on a logarithmic scale. For example, the half-life of C is 5, years. In the first 5, years, the organism will lose half of its C isotopes. In another 5, years, the organism will lose another half of the remaining C isotopes. This process continues over time, with the organism losing half of the remaining C isotopes each 5, years.
Fossils are collected along with rocks that occur from the same strata. These samples are carefully cataloged and analyzed with a mass spectrometer. The mass spectrometer is able to give information about the type and amount of isotopes found in the rock. Scientists find the ratio of parent isotope to daughter isotope. By comparing this ratio to the half-life logarithmic scale of the parent isotope, they are able to find the age of the rock or fossil in question. Micraster echinoid fossil from England. An example of preservation by replacement. From Wikipedia, the free encyclopedia.
Preserved remains or traces of organisms from a past geological age. For the band, see Dinosaur Bones. For other uses, see Fossil disambiguation. Biogeography Extinction event Geochronology Geologic time scale Geologic record History of life Origin of life Timeline of evolution Transitional fossil. Evolution of various taxa. Introduction to evolution Common descent Phylogeny Cladistics Biological classification.
History of paleontology Timeline of paleontology. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.
August Learn how and when to remove this template message. Geochronology and Relative dating. Ghost lineage , Signor—Lipps effect , and Biostratigraphy. List of fossil sites. List of transitional fossils. Fossil trading and Fossil collecting. Paleontology portal Geology portal. San Diego Natural History Museum:: Your Nature Connection in Balboa Park:: Retrieved 5 November Meet your microbial mom". Retrieved 15 November Retrieved 21 August Wade, Nicholas 21 August The New York Times.
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How Is Radioactive Dating Used to Date Fossils? | Sciencing
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Natural history Biogeography Extinction event Geochronology Geologic time scale Geologic record History of life Origin of life Timeline of evolution Transitional fossil. History of paleontology History of paleontology Timeline of paleontology.
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