— graptolitic /grap'teuh lit"ik/ , adj.
/grap"teuh luyt'/ , n.
any colonial animal of the extinct class Graptolithina, most common in the Ordovician and Silurian Periods, thought to be related to the pterobranchs.
[ 1830-40; graptó ( s ) painted, marked with letters (v. adj. from gráphein to write) + -LITE ]