Watsonosteus

Watsonosteus is an extinct genus of coccosteid arthrodire placoderm from the Late Givetian stage of the Middle Devonian period. Fossils are found in the Orkney Islands, Scotland. It was a small placoderm with a total body length of 57 cm, with the largest individuals reaching lengths of 1 m. It is one of the few arthrodires for which complete body fossils are known.

Phylogeny
Watsonosteus is a member of the family Coccosteidae, which belongs to the clade Coccosteomorphi, one of the two major clades within Eubrachythoraci. The cladogram below shows the phylogeny of Watsonosteus: