lobe-finned fish vs crossopterygian

lobe-finned fish and crossopterygian both are nouns.

Word	Noun	Adjective	Verb	Adverb
lobe-finned fish	Yes	No	No	No
crossopterygian	Yes	No	No	No

As nouns, lobe-finned fish and crossopterygian are synonyms defined as:

lobe-finned fish and crossopterygian: any fish of the order Crossopterygii; most known only in fossil form

Other synonyms of lobe-finned fish include lobefin.

lobe-finned fish (noun)	crossopterygian (noun)
any fish of the order Crossopterygii; most known only in fossil form	any fish of the order Crossopterygii; most known only in fossil form