Coccosteus cuspidatus (Arthrodire) Armored Fish Middle Devonian Old Red Sandstone Orkney, Scotland The arthrodire Coccosteus was a placoderm with heavy bony plates covering the head and neck, and gnathal (tooth-like) plates at the front of its mouth. The heavy head plates were covered with large tubercles made of semi-dentine, while the back of the body was covered with smooth skin. The interior skeleton was made of cartilage and was rarely preserved. Most placoderms are known only from head plates, but this complete specimen also preserves the spinal column. Placoderms dominated the Devonian seas but disappeared during a mass extinction near the end of the Devonian Period. Fish body: 29 cm Free shipping!