Placoderms (“Tablet Skins”)
Early jawed fishes that bore jointed bony plates over the head and thorax.
Rear parts were naked or covered by small scales.
Jaw-mounted bony plates served as teeth.
Dominated brackish and near-shore ecosystems.
Some stretched 30 feet, but most were inches long.
Spread to both marine and freshwater habitats.
Became the first vertebrates to colonize the open ocean.
Went extinct at the end of the Devonian.
Image courtesy of Nobu Tamora.
Coccosteus decipiens, a placoderm of Europe and North America.