holocephalan vs chondrichthian

holocephalan and chondrichthian both are nouns.

Word	Noun	Adjective	Verb	Adverb
holocephalan	Yes	No	No	No
chondrichthian	Yes	No	No	No

As nouns, chondrichthian is a hypernym of holocephalan; that is, chondrichthian is a word with a broader meaning than holocephalan:

holocephalan: fish with high compressed head and a body tapering off into a long tail
chondrichthian: fishes in which the skeleton may be calcified but not ossified

Other hypernyms of holocephalan include cartilaginous fish.

holocephalan (noun)	chondrichthian (noun)
fish with high compressed head and a body tapering off into a long tail	fishes in which the skeleton may be calcified but not ossified