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II. All the species of the family have a wide variety of "displays" --- ritualized social signal patterns.

III. Some species seem to employ olfactory signals. These have not been studied in any detail. Apparently usually used to facilitate specific and individual recognition. Strange animals introduced to one another for the first time usually sniff at one another immediately. The initial reaction. Sometimes done in a very rigid and formalized manner. 
Olfactory signals of various types are also associated with sexual behavior in a few species.
IV. All the species are extremely vocal. Vocal patterns always or almost always the most important (and most frequent) signals.
The vocal patterns of most species range from thin, high-pitched, squeaks and whistles to low-pitched (and usually loud) barks, grunts, and roars. All the vocal patterns appear to be produced when two or more different types of motivation are in conflict and/or when one type of motivation is thwarted. The vocal repertories of different species are superficially ver different; but they are (largely) composed of homologous elements. 
By comparing the vocal repertories of different species, it may be possible to determine the "basic" vocal repertory of the family as a whole.

The differences between the vocal repertories of different species seem to ne due to a few relatively simple changes in the course of evolution:
1. An increase in the number of distinct patterns (division).
2. Different inter0connections between patterns.
3. Loss of some patterns (not fusion). Example: Squ - Wh.
4. General changes in tone. Examples:
a. Howler monkeys. All grunts, barks, roars (as adults).
b. Marmosets. All bird-like squeaks and whistles.
5. Changes in the thresholds at which transitions between different tones and/or rhythms occur. Examples

Transcription Notes:
not sure about line as well as encircled 2 in the top right