The Santarem marmoset (Mico humeralifera), also known as a black and white tassel-ear marmoset, is a species of 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.