Climatius (from Greek: κλίμα klíma, 'gradation')[1] 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.

[3] Climatius represents an important evolutionary link in understanding early jawed vertebrates.

Its distinct features, such as double-layered globular calcified cartilage and specialized dental structures, offer crucial insights into the morphological diversification and adaptive strategies of Devonian fish.

It was a small fish, at 7.5 centimetres (3 in) long, and to discourage predators, Climatius sported fifteen sharp spines.