osteostracan

English Thesaurus

1. extinct jawless fish of the Devonian with armored head (noun.animal)

hypernym	:	agnathan, jawless fish, jawless vertebrate,
definition	:	eel-shaped vertebrate without jaws or paired appendages including the cyclostomes and some extinct forms (noun.animal)

member meronym	:	cephalaspida, osteostraci, suborder cephalaspida, suborder osteostraci,
definition	:	extinct group of armored fish-like vertebrates; taxonomy is not clear (noun.animal)