Topic summary
Catarrhine
Extracted from the Wikipedia article Catarrhini.
Description
The technical distinction between the New World platyrrhines and Old World catarrhines is the shape of their noses. The platyrrhines (from Ancient Greekplaty-, "flat", and rhin-, "nose") have nostrils which face sideways. The catarrhines (from Ancient Greek katà-, "down", and rhin-, "nose") have nostrils that face downwards. Catarrhines also never have prehensile tails, and have flat fingernails and toenails, a tubular ectotympanic (ear bone), and eight, not 12, premolars, giving them a dental formula of 2.1.2.32.1.2.3, indicating 2 incisors, 1 canine, 2 premolars, and 3 molars on each side of the upper and lower jaws.