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 fishlike jawless vertebrate having a heavily armored body; of the Paleozoic

Heterostraci, suborder Heterostraci - extinct group of armored jawless fishes or fishlike vertebrate; taxonomy is not clear

Cephalaspida, Osteostraci, suborder Cephalaspida, suborder Osteostraci - extinct group of armored fishlike vertebrates; taxonomy is not clear