The Geoffroy's tufted-ear marmoset has nonopposable thumbs and nails of the digits which are claw-like.
The Geoffroy's tufted-ear marmoset is found in the Atlantic rainforests of south-east Brazil (Rylands et al., 1993). This species occurs in the lowlands of the forest (Rylands and de Faria, 1993).
The Geoffroy's tufted-ear marmoset is gummivorous. This species has also been known to follow army ant swarms which flush many organisms up towards the trees making them available for the marmosets (Rylands et al., 1989).
The Geoffroy's tufted-ear Marmoset moves through the forest quadrupedally, but is capable of leaping (Fleagle, 1988).