Definitions for index fossil
in·dex fos·sil

Princeton's WordNetRate this definition:0.0 / 0 votes

1. index fossil, guide fossilnoun

   a fossil known to have lived in a particular geologic age that can be used to date the rock layer in which it is found

WiktionaryRate this definition:4.5 / 6 votes

1. index fossilnoun

   Any ancient remains of a plant or animal that lived during a specific geological period and that can be used to date the containing rocks.

WikipediaRate this definition:0.0 / 0 votes

1. index fossil

   Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. The primary objective of biostratigraphy is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to help identify biozones, as they make up the basic biostratigraphy units, and define geological time periods based upon the fossil species found within each section. Basic concepts of biostratigraphic principles were introduced many centuries ago, going as far back as the early 1800s. A Danish scientist and bishop by the name of Nicolas Steno was one of the first geologists to recognize that rock layers correlate to the Law of Superposition. With advancements in science and technology, by the 18th century it began to be accepted that fossils were remains left by species that had become deceased and were then preserved within the rock record. The method was well-established before Charles Darwin explained the mechanism behind it—evolution. Scientists William Smith, George Cuvier, and Alexandre Brongniart came to the conclusion that fossils then indicated a series of chronological events, establishing layers of rock strata as some type of unit, later termed biozone. From here on, scientists began relating the changes in strata and biozones to different geological eras, establishing boundaries and time periods within major faunal changes. By the late 18th century the Cambrian and Carboniferous periods were internationally recognized due to these findings. During the early 20th century, advancements in technology gave scientists the ability to study radioactive decay. Using this methodology, scientists were able to establish geological time, the boundaries of the different eras (Paleozoic, Mesozoic, Cenozoic), as well as Periods (Cambrian, Ordovician, Silurian) through the isotopes found within fossils via radioactive decay. Current 21st century uses of biostratigraphy involve interpretations of age for rock layers, which are primarily used by oil and gas industries for drilling workflows and resource allocations.

ChatGPTRate this definition:0.0 / 0 votes

1. index fossil

   An index fossil is a fossil that is used to define and identify geological periods. It is distinct, widespread, and represents a type of organism that existed only for a relatively short period of time during a specific geological period. Due to their unique characteristics and brief existence, they provide a useful tool for dating rock layers and correlating the age of different geological formations worldwide.

WikidataRate this definition:3.2 / 5 votes

1. Index fossil

   Index fossils are fossils used to define and identify geologic periods. They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived, then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of fossils are particularly valuable. The best index fossils are common, easy-to-identify at species level, and have a broad distribution—otherwise the likelihood of finding and recognizing one in the two sediments is minor. Ammonites fit these demands well, and are the best-known fossils that have been widely used for this. Other important groups that provide index fossils are the corals, graptolites, brachiopods, trilobites, and echinoids. Conodonts may be identified by experts using light microscopy such that they can be used to index a given sample with good resolution. Fossilized teeth of mammals have also been used.

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How to pronounce index fossil?

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Numerology

1. Chaldean Numerology

   The numerical value of index fossil in Chaldean Numerology is: 9

2. Pythagorean Numerology

   The numerical value of index fossil in Pythagorean Numerology is: 1

References

1. ^ Princeton's WordNet
   http://wordnetweb.princeton.edu/perl/webwn?s=index fossil
2. ^ Wiktionary
   https://en.wiktionary.org/wiki/Index_Fossil
3. ^ Wikipedia
   https://en.wikipedia.org/wiki/Index_Fossil
4. ^ ChatGPT
   https://chat.openai.com
5. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=index fossil