166(BS-02-3) Topographical analysis of late Miocene catarrhines molars from Nakali in Kenya

Nakali, a Late Miocene fossil site in Kenya, had a great diversity of primates including old type of catarrhines (i.e. victoriapithecidae or small non-cercopithecoid catarrhines) and new type of catarrhines (Nakalipithecus, Microcolobus or cercopithecidae). There would be food competition and segregations among them. The purpose of this study was to investigate dietal adaptation of Nakali fossil cercopithecidae using the morphometrical analysis and the topographical analysis for outer morphology of molars. Both Nakali Microcolobus and indeterminate cercopithecoid had much derived occlusal morphology from victoriapithecidae toward cercopithecidae. Occlusal shape of Nakali Microcolobus was situated between extant cercopithecinae and colobinae monkeys, and indeterminate Nakali cercopithecoid was within an extant cercopithecini range according to morphometrical analysis. Nakali Microcolobus had relatively higher occlusal relief, steeper occlusal surface, and sharper ridge than extant cercopithecinae, but not as much as extant colobinae. Indeterminate Nakali cercopithecoid had similar degree of occlusal releaf and sharpness of ridges to extant cercopithecinae, although it had significantly steeper occlusal surface than extant cercopithecinae. This early colobus already had more folivorous diet than living guenons or other species from Nakali, but less than extant colobines. Indeterminate Nakali cercopithecoid had a fruit dominant diet with some young leaves like extant cercopithecinae.