The Agnathans were actually armoured fish but more fish evolved from
these first fish. The Acanthodians, or spiny fish, had jaws unlike the Aganthans (BBC, 1998). They had a short,
deep body, five fins on it's belly and of course, it has spines all over it's body (BBC, 1998). These fish went extinct in the Carboniferous period (BBC, 1998).
The Placoderms, plate skinned fish, which originated in the late Silurian, also lived during the Devonian and they had joints between their head and necks (Parrish, 1998). This was so their mouths could open wide and they also had plates all over their head (Parrish, 1998).