biped vs fauna

biped and fauna both are nouns.

Word	Noun	Adjective	Verb	Adverb
biped	Yes	Yes	No	No
fauna	Yes	No	No	No

As nouns, fauna is a hypernym of biped; that is, fauna is a word with a broader meaning than biped:

Other hypernyms of biped include animal, animate being, beast, brute, creature.

biped (noun)	fauna (noun)
an animal with two feet	a living organism characterized by voluntary movement
	all the animal life in a particular region or period

biped (adjective)	fauna (adjective)
having two feet