The Family Callithricidae (commonly called marmosets and tamarins) is a group of small New World monkeys found in the tropical forests of Central and South America. These primates are characterized by tiny bodies, claw-like nails (except on the big toe), and long tails, which aid in balance but are not prehensile. Callithricids are highly social, living in family groups with cooperative care of offspring, and they have a varied diet that includes fruits, insects, sap, and small animals. Known for their agility in the forest canopy, they are important for seed dispersal and maintaining tropical ecosystem health.