Complex sentence: Cotton-top tamarins exhibit prosocial behavior that benefits other members of the group, and are well known for engaging in cooperative breeding whereby the group's subordinate adults help in rearing the offspring of the dominant pair.
Split into simpler sentences: Cotton-top tamarins exhibit prosocial behavior that benefits other members of the group, and are well known for engaging in cooperative breeding. Accordingly, a group's subordinate adults help in rearing the offspring of the dominant pair.