What is "climatiiformes"

The Climatiiformes is an order of extinct fish belonging to the class Acanthodii. Like most other "spiny sharks", the Climatiiformes had sharp spines. These animals were rather small in size (about 4 in or 10 cm) and lived from the Late Silurian to the Early Carboniferous period. The type genus is Climatius. The order splits into the suborders Climatiida and Diplacanthida, which themselves split into several families.