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Any of numerous extinct colonial marine animals chiefly of the orders Dendroidea and Graptoloidea of the late Cambrian to the early Mississippian Periods, whose fossil remains are often used to date the rocks of the Silurian and Ordovician ages.

[Greek graptos, written (from graphein, to write; see graphic) + -lite (from the resemblance of the fossils' impressions on shale to markings on a slate).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Palaeontology) 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 and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈgræp təˌlaɪt)

any extinct marine animal of the class Graptolithina that grew in branching, floating colonies preserved as traces in Ordovician through Mississippian deposits.
[1830–40; < Greek graptó(s) painted, marked with letters (v. adj. of gráphein to write) + -lite]
grap`to•lit′ic (-ˈlɪt ɪk) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Evolution of the earliest graptolites and other hemichordates.
These include fossils of bacteria, algae, plants, sponge, corals, worms, bryoza, brachiopods, mollusca (including cephalopods, bivalves, and gastropods), echinodermata, graptolites, arthropods, fish, amphibians, reptiles, and mammals.
Since their discovery in the 19th-century, some of the biggest questions in hemichordate evolution have focused on the group's origins and the relationship between its two main branches: the enteropneusts and the pterobranchs, including graptolites.
He said these tubes are the missing link connecting the two main hemichordata groups, which also included the now-extinct graptolites.
On Cornwallis Island he discovered graptolites, important index fossils for the lower Paleozoic, in an unusually complete state of preservation.
Sevier Shale produces graptolites, sometimes pyritized, trilobites, and brachiopods.
Coverage includes an overview of the topic followed by individual chapters on fossil classification and evolution, sponges, corals, bryozoans, brachiopods, echinoderms, trilobites, mollusks, graptolites, vertebrates, land plants, microfossils, trace fossils, precambrian life, and phanerozoic life.
We find no pentamerus brachiopods or cystoid crinozoans or psilopsid plants above Devonian strata, no graptolites above Mississippian strata, and no trilobites or rugose corals above Permian strata.
This level is close to the first appearance of Dicellograptus, however, graptolites are extremely rare or absent in the main part of the Uhaku Stage.
Since then, volume after volume has appeared, dealing with trace fossils, spores, conodonts, sponges, plants, graptolites, foraminifers, brachiopods and, yes, more trilobites (according to some, too many, but never mind).