The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.
a group of fishes that formerly united the extinct classes Ostracodermi and Placodermi. The fishes were characterized by a bony external armor that partially or completely covered the head and the anterior part of the trunk.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.