Climatiiformes (spiny sharks; class Acanthodii) One of the larger orders of fossil fish that had bony jaws and body skeleton, ganoid scales, a heterocercal tail, and stout spines located before the dorsal, anal, pectoral, and pelvic fins. One of the better-known forms, Climatius, carried five additional pairs of fins along the belly and reached a length of only 8 cm. These fish may actually be half-way between the sharks and the bony fish.

Climatiiformes One of the larger orders of fossil fish belonging to the class Acanthodii. They possessed bony jaws and body skeleton, ganoid scales, a heterocercal tail, and stout spines located before the dorsal, anal, pectoral, and pelvic fins. One of the better-known forms, Climatius, carried five additional pairs of fins along the belly and reached a length of only 8 cm. These ‘spiny sharks’ may actually be halfway between the sharks and the bony fish (Osteichthyes).