The Santarem Marmoset (Callithrix humeralifera), also known as a Black And White Tassel-ear Marmoset is a marmoset endemic to Brazil. It is found in a very restricted area between the Rio Tapajos and lower Rio Madeira and Rio Roosevelt.
It lives in groups of 5 to 15 individuals, feeding and is an omnivorous animal. It lives, mainly, in areas with dense viney vegetation.