- any colonial animal of the extinct class Graptolithina, most common in the Ordovician and Silurian Periods, thought to be related to the pterobranchs.
Origin of graptolite
1830–40; < Greek graptó(s) painted, marked with letters (verbal adjective from gráphein to write) + -lite
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for graptolite
The strata consist of greywackes, flags and shales with seams and zones of graptolite shale which yield fossils sparingly.
- any extinct Palaeozoic colonial animal of the class Graptolithina, usually regarded as related to either the hemichordates or the coelenterates: a common fossil, used to determine the age of sedimentary rocks
C19: from Greek graptos written, from graphein to write + -lite
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
Word Origin and History for graptolite
Online Etymology Dictionary, © 2010 Douglas Harper
- Any of numerous hemichordates of the class Graptolithina. Graptolites form colonies consisting of interlocked cuplike chambers arranged in one or more branches and covered by an exoskeleton. They flourished from the late Cambrian to the early Mississippian Period, and were thought to be extinct until 1992 when scientists discovered what is believed to be a living species. Graptolites are important index fossils used to date the rocks of the Silurian and Ordovician Periods.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.