Early Devonian cartilaginous fish

Climatius (from , 'gradation') is an extinct genus of spiny shark. This genus is known from the Early Devonian (Lochkovian) of Europe, previously considered Silurian remains actually belong to Nostolepis instead.

Ischnacanthus is an extinct genus of acanthodian jawed fish. It lived from the Pridoli to the Lochkovian. The type species I. gracilis is only known from Lochkovian.

Mesacanthus ('middle spine') is an extinct genus of acanthodian fish from Devonian Scotland. It is among the more primitive of the Devonian acanthodians.