catarrhine vs catarrhinian

catarrhine is a noun but catarrhinian is not a noun.

Word	Noun	Adjective	Verb	Adverb
catarrhine	Yes	Yes	No	No
catarrhinian	No	Yes	No	No

As adjectives, catarrhine and catarrhinian are synonyms defined as:

catarrhine and catarrhinian: of or related to Old World monkeys that have nostrils together and opening downward

catarrhine (noun)	catarrhinian (noun)
of Africa or Arabia or Asia; having nonprehensile tails and nostrils close together

catarrhine (adjective)	catarrhinian (adjective)
of or related to Old World monkeys that have nostrils together and opening downward	of or related to Old World monkeys that have nostrils together and opening downward