Which specific adaptation helps define the New World monkey classification regarding their nasal structure?

Answer

Their nostrils are spaced widely apart and point sideways

The woolly monkeys are identified as New World monkeys, a geographical distinction further refined within the Primate order based on morphology, particularly the structure of the nose. A key distinguishing feature that separates New World monkeys from their Old World counterparts is the orientation and spacing of their nostrils. For New World primates, this typically means that the openings are separated by a significant distance, causing them to face outwardly or sideways. This anatomical difference is one of the primary structural cues used in classification to immediately place these American primates apart from those originating in Africa or Asia.

Which specific adaptation helps define the New World monkey classification regarding their nasal structure?
classificationMonkeyPrimate