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|Noun||1.||Ostracodermi - extinct group of armored jawless vertebrates; taxonomy is not clear|
animal order - the order of animals
Agnatha, superclass Agnatha - superclass of eel-shaped chordates lacking jaws and pelvic fins: lampreys; hagfishes; some extinct forms
ostracoderm - extinct fish-like jawless vertebrate having a heavily armored body; of the Paleozoic
Heterostraci, suborder Heterostraci - extinct group of armored jawless fishes or fish-like vertebrate; taxonomy is not clear