120(BS-02-2) Paleoenvironment of Nakali inferred from extant colobine ecology

Numerous cercopithecid fossils, including several partial skeletons, have been collected from the late Miocene Nakali Formation. The majority of these specimens belong to Microcolobus, but other taxa might be present. Microcolobus is equivalent to the olive colobus in size, which is the smallest (outstandingly small) extant colobine species and has the most geographically limited distribution. Because of its narrow adaptive zone, ecology of such a small colobine might provide a hint to reconstruct the paleoenvironment of NA 60. Ecology of the olive colobus is greatly influenced by predator aversion and selective feeding strategy, being closely tied to its small body size. Although any inference from a single extant species should be made cautiously, it would be safe to conclude that Microcolobus could have survived only under the closed canopy.