Pteraspis (meaning wing shield) is an extinct genus of primitive jawless fish that lived in the Pragian epoch of the Devonian period in what is now Britain and Belgium.Like other heterostracan fishes, Pteraspis had a protective armored plating covering the front of its body. Though lacking fins other than its lobed tail, it is thought to have been a good swimmer thanks to stiff, wing-like protrusions derived from the armoured plates over its gills.