graptolite

UK: /ˈɡræptəˌlaɪt/ US: (grap′tə līt′)

WordReference Random House Unabridged Dictionary of American English © 2025

grap•to•lite  (grap′tə līt′), n. 

1. Paleontology any colonial animal of the extinct class Graptolithina, most common in the Ordovician and Silurian Periods, thought to be related to the pterobranchs.

• Greek graptó(s) painted, marked with letters (verb, verbal adjective, adjectival from gráphein to write) + -lite
• 1830–40;

grap•to•lit•ic  (grap′tə lit′ik), adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

graptolite / ˈɡræptəˌlaɪt/ noun

1. 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

Etymology: 19th Century: from Greek graptos written, from graphein to write + -lite