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index fossil
index fossil (index species, zone fossil) Fossil whose presence is chosen to denote the zone in which it occurs and after which the zone is named. Index fossils are selected for their distinctiveness and/or abundance. To be of use in biostratigraphy, ideally an index fossil should have a narrow range in time (i.e. to have undergone rapid evolutionary change) but have had a wide geographical distribution. Trilobites (Cambrian); graptolites (Ordovician and Silurian); ammonites (Jurassic); and foraminifera (Cretaceous and Cenozoic) are among the most notable index fossils.
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AILSA ALLABY and MICHAEL ALLABY. "index fossil." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "index fossil." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-indexfossil.html AILSA ALLABY and MICHAEL ALLABY. "index fossil." A Dictionary of Earth Sciences. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-indexfossil.html |
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index fossil
index fossil (zone fossil) An animal fossil of a group that existed continuously during a particular span of geological time and can therefore be used to date the rock in which it is found. Index fossils are found chiefly in sedimentary rocks. They are an essential tool in stratigraphy for comparing the geological ages of sedimentary rock formations. Examples are ammonites and graptolites.
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"index fossil." A Dictionary of Biology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. "index fossil." A Dictionary of Biology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O6-indexfossil.html "index fossil." A Dictionary of Biology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-indexfossil.html |
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index fossil
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Cite this article
MICHAEL ALLABY. "index fossil." A Dictionary of Zoology. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "index fossil." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O8-indexfossil.html MICHAEL ALLABY. "index fossil." A Dictionary of Zoology. 1999. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-indexfossil.html |
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index fossil
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Cite this article
MICHAEL ALLABY. "index fossil." A Dictionary of Ecology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "index fossil." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O14-indexfossil.html MICHAEL ALLABY. "index fossil." A Dictionary of Ecology. 2004. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-indexfossil.html |
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