The meaning of Graptolites and additional information.

Graptolite(n.) One of numerous species of slender and delicate fossils, of the genus Graptolites and allied genera, found in the Silurian rocks. They belong to an extinct group (Graptolithina) supposed to be hydroids.

Graptolitic(a.) Of or pertaining to graptolites; containing graptolites; as, a graptolitic slate.