Dictionary
het•er•os•tra•can
Pronunciation: (het"u-ros'tru-kun), [key]—
n. Paleontol.
any of several ostracoderms of the order Heterostraci, from the Silurian and Devonian Periods, having the anterior part of the body enclosed in bony plates.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.