What is "hiodontiformes"

Hiodontiformes is a relatively new order of fish, consisting of the two living species of the mooneye family Hiodontidae and three genera of extinct types.

These are traditionally classified with the Osteoglossiformes, and many authorities still do, but fossil study of the extinct Yanbiania suggest that the hiodontids separated from other osteoglossiforms early, and thus belong to a separate order.