Dictionary.com

index fossil

Save This Word!

noun Geology, Paleontology.

a widely distributed fossil, of narrow range in time, regarded as characteristic of a given geological formation, used especially in determining the age of related formations.

QUIZZES

THINK YOU’VE GOT A HANDLE ON THIS US STATE NICKNAME QUIZ?

Did you ever collect all those state quarters? Put them to good use on this quiz about curious state monikers and the facts around them.
Question 1 of 8
Mississippi’s nickname comes from the magnificent trees that grow there. What is it?
Also called guide fossil.

Origin of index fossil

First recorded in 1895–1900
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

Example sentences from the Web for index fossil

British Dictionary definitions for index fossil

index fossil

noun

a fossil species that characterizes and is used to delimit a geological zoneAlso called: zone fossil
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for index fossil

index fossil
[ ĭndĕks′ ]

The fossil remains of an organism that lived in a particular geologic age, used to identify or date the rock or rock layer in which it is found. The best type of index fossils are usually those of swimming or floating organisms that evolved quickly (and therefore did not cover a long span of geologic history) and were able to spread over large areas. Ammonites and graptolites are good index fossils.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Book Your Online Tutor Now