†order Cephalaspidiformes Berg 1937 (vertebrate)
Petromyzontida - Cephalaspidiformes
Alternative spelling: Cephalaspidoformes
Synonym: Osteostraci Lankaster 1868
Parent taxon: Cephalaspidomorphi according to J. S. Nelson et al. 2016
See also Dineley and Metcalf 1999, Gadow 1898, Hay 1902, Long 2011, Obruchev 1964 and Sepkoski 2002
Sister taxa: Gilpichthyidae, Pipisciidae, Pituriaspidiformes, Birkeniiformes, Galeaspidiformes, Cephalaspidida, Atelaspidiformes
Subtaxa: Aachenaspis Ateleaspidiformes Benneviaspidida Benneviaspidiformes Camptaspis Cornuata Fieldingaspis Meelaidaspis Ohesaareaspis Thyestiida Tremataspidida Tremataspidiformes Tuvaspis Waengsjoeaspis Yvonaspis Zenaspidida
Ecology: fast-moving nektonic carnivore