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

When the world-girdling ice came at the end of the Ordovician period roughly 440 million years ago, only a few species of graptolite survived the mass extinction.

From Scientific American

There is a golden spike hiding in a rock face outside the village of Moffat in Scotland that marks the end of the Ordovician, denoted by the appearance of these graptolite survivors—Akidograptus ascensus and Parakidograptus acuminatus, to give them their scientific names.

From Scientific American

Many Graptolite zones, showing a constant uniformity of succession, paralleled in this respect only by the longer known Ammonite zones of the Jurassic, have been distinguished in Britain and northern Europe, each marked by a characteristic species.

From Project Gutenberg

The Graptolite polyparies vary considerably in size: the majority range from 1 in. to about 6 in. in length; few examples have been met with having a length or more than 30 in.

From Project Gutenberg

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

From Project Gutenberg