Hiodontiformes is a relatively new order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, consisting of the two living species of the mooneye

Mooneye

The mooneyes are a family, the Hiodontidae, of primitive ray-finned fish comprising two living and three extinct species in the genus Hiodon. They are large-eyed, fork-tailed fish that physically resemble shads. Their common name comes from the metallic gold or silver shine of their eyes.The higher...

 family Hiodontidae and three genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of extinct types.

These are traditionally classified with the Osteoglossiformes

Osteoglossiformes

Osteoglossiformes is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of the living species inhabit freshwater...

, 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.

External links

• Tree of Life entry for Hiodontiformes