artiodactyl vs artiodactylous

artiodactyl is a noun but artiodactylous is not a noun.

Word	Noun	Adjective	Verb	Adverb
artiodactyl	Yes	Yes	No	No
artiodactylous	No	Yes	No	No

As adjectives, artiodactyl and artiodactylous are synonyms defined as:

artiodactyl and artiodactylous: of or relating to or belonging to mammals of the order Artiodactyla

Other synonyms of artiodactyl include even-toed.

artiodactyl (noun)	artiodactylous (noun)
placental mammal having hooves with an even number of functional toes on each foot

artiodactyl (adjective)	artiodactylous (adjective)
of or relating to or belonging to mammals of the order Artiodactyla	of or relating to or belonging to mammals of the order Artiodactyla