Dental morphometric variation between African and Asian colobines, with special reference to the other Old World...

In order to reveal differences between Asian and African colobines (nonhuman primates) in terms of dietary adaptation and evolutionary development, a large number of the species of the cercopithecoids (Old World monkeys) was analyzed with morphometric methods. In addition to the raw data and ratios, deviations of the colobines, predicted from allometric baselines derived from the cercopithecines, were analyzed by univariate and multivariate analyses. Some results indicated that there exists significant differentiation between colobines and cercopithecines; the latter exhibit a larger dental scale relative to body size, and the less developed front teeth of the colobines may be related to their fewer frequent incisal use, compared with those of the cercopithecines. With regard to variations between the two subtribes of the colobines, which are found in African (Colobina) and Asia (Presbytina), the Asian subtribe displays a larger scale of postcanine teeth, referring to the results of the raw data. This may correspond to their larger body size. While ratios were considered, the variation between Presbytina and Colobina was diminished greatly. This implies that, unlike the scenario postulated to reflect the relationships between colobines and cercopithecines--which supposes that their differentiation is in both size and shape--the variation between the two subtribes is principally size associated: relative to body size Colobina exhibits more emphasized incisors, but less developed postcanine teeth--with the exception of width of M3s. In other words, the relationships between teeth and body size of the African colobines are more similar to those of the cercopithecines. This implies, compared to their Asian partners, that African colobines share more similarities with cercopithecines. This may be related to the episodes in which African species underwent a longer period of sharing environmental and climatic patterns with the cercopithecines that moved to Asia about 5 or 8 million years ago. Canines were found to be important in distinguishing colobines from cercopithecines and in separating one subtribe from the other.