any of several extinct jawless fishes of the Ordovician, Silurian, and Devonian periods, having the body enclosed in an armor of bony plates.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
British Dictionary definitions for ostracoderm
any extinct Palaeozoic fishlike jawless vertebrate of the group Ostracodermi, characterized by a heavily armoured body
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for ostracoderm
Any of various extinct primitive jawless fishes of the Ordovician through the Devonian Period. Most ostracoderms had their heads or entire bodies encased in fused bony plates. Some or all ostracoderms are sometimes classified together with the modern cyclostomes (lampreys and hagfish).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.