graptolite

American  

[grap-tuh-lahyt] / ˈgræp təˌlaɪt /

noun

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

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graptolite British  

/ 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

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graptolite Scientific  

/ grăp′tə-līt′ /

1. 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.

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Other Word Forms

• graptolitic adjective

Etymology

Origin of graptolite

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

Example Sentences

"The mere presence of a graptolite," he says, "will at once decide that the enclosing rock is Silurian;" and he says this, notwithstanding repeated warnings against such generalizations.

From Essays: Scientific, Political, & Speculative, Vol. I by Spencer, Herbert

The strata consist of greywackes, flags and shales with seams and zones of graptolite shale which yield fossils sparingly.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various

These consist of greywackes, flags and shales with bands of dark graptolite shales, the finer sediments being often well cleaved.

From Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 8 "Dubner" to "Dyeing" by Various