Catarrhini is an infraorder of the Primates. It contains the Superfamilies Cercopithecoidea (Old World monkeys) and the hominoidea (hominoids). The hominoidea are parted in the family hominidae (which contain humans, chimpanzee, gorilla, bonobo and orangutan) and the family hylobatidae (gibbons and siamang). Some count the orangutan as own family, called pongidae.
Older authors described humans and their most close extinct relatives/ancestors as family on its own and placed the great apes in the family pongidae. (see Primates).
They also contain several extinct taxa.
The other infraorder of the primates are the Platyrrhini (New World monkeys), which live in south america.
Catarrhini means narrow nose and describes their narrow, downward pinting nostrils. Generally, they are diurnal and their tails (if they have tails at all) can't be used as "fifth hand". They have flat fingernails.
Their dental formula is
Most species show considerable sexual dimorphism
and do not form a pair bond. Most but not all species live in social groups.
They are native to Africa
. (exept us of course)