†order Cephalaspidiformes (vertebrate)
Petromyzontida - Cephalaspidiformes
Alternative spelling: Cephalaspidoformes
Synonym: Osteostraci
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, Atelaspidiformes, Ateleaspis, Birkeniiformes, Pituriaspidiformes, Cephalaspidida, Galeaspidiformes
Subtaxa: Aachenaspis Benneviaspidiformes Benneviaspis Cornuata Euphaneropidae Fieldingaspis Ilemoraspis Kiaeraspis Oeselaspis Procephalaspis Saaremaaspis Sclerodus Tannuaspis Thyestes Thyestiida Timanaspis Tremataspidida Tremataspidiformes Tuvaspis Tyriaspis Waengsjoeaspis
Ecology: fast-moving nektonic carnivore