Scent in communication
One South American group, the marmosets (e.g. Callithrix penicillata) and tamarins (e.g. Leontocebus leucopus), still use scent a great deal in communication even though they are active during the day. The males gnaw the bark of a branch and then soak it with urine. But they also have extremely elaborate adornments - moustaches, ear-tufts and wig-like crests - which they display during their social encounters; and they threaten one another with high-pitched twittering calls. Their manner of rearing their young is less specialized than for the old world apes.