Protospinax is an extinct genus of cartilaginous fish from the Middle to Late Jurassic of Europe and Russia. The type species, P. annectans, was found in the Solnhofen limestones of southern Bavaria.

Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes