1Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2Department of Anthropology, Northern Illinois University, 3Department of Anthropology, University of Illinois at Urbana-Champaign, 4Human Origins Program, National Museum of Natural History, Smithsonian Institution
Friday All day, Plaza Level
It has been suggested that mandibular premolar molarization in fossil hominins is an adaptation for the consumption of mechanically challenging food items. This study used an extant primate model to test the hypothesis that premolar molarization correlates with dietary toughness. The callitrichids Callimico goeldii, Saguinus fuscicollis, and Saguinus labiatus are closely related and live sympatrically in the Amazon. Although there is significant overlap in the dietary items they consume, their mandibular postcanine morphology differs. Standard metric and 2D geometric morphometric analyses conducted on the mandibular postcanines of these taxa in the collection of the NMNH demonstrate that, even when the effects of differences in body size are taken into account, Callimico goeldii and S. labiatus have molarized P4s when compared to S. fuscicollis. Food items from the diets of these taxa were collected over a six-week period during the months of June and July 2011at Camp Callimico, Bolivia and toughness properties were tested using a Lucas field mechanical tester. Among four major food categories (arthropods, exudates, fruits, fungus) masticated by the callitrichid taxa, fungus was found to be significantly tougher than other food items. Fungus accounts for almost one-third the diet of Callimico goeldii, and S. labiatus is known to consume fungus more often than S. fuscicollis, although it does not form a significant part of its diet. In callitrichids, molarized P4s may be an adaptation that allows taxa to shift to a diet with a higher percentage of tough food items.
This study was funded by a NSF-GRFP to KS and NSF-IGERT DGE-0801634.