Holocephali

Holocephali Temporal range: Devonian–Recent
Hydrolagus colliei
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Holocephali
Orders
Chimaeriformes †Petalodontiformes †Iniopterygiformes  ?†Eugeneodontida

Holocephali ("complete heads") is a subclass of cartilaginous fish, of which the order Chimaeriformes is the only surviving group. Holocephali has an extensive fossil record that starts during the Devonian period. However, most fossils are teeth, and the body forms of numerous species are not known, or, at best, poorly understood.