1Department of Anthropology, San Francisco State University, 2Human Evolution Research Center, University of California Berkeley
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The interconulus is a trait that expresses between the protocone and hypocone of the maxillary molars in populations of Papio and Macaca. The interconulus is a continuously varying trait that ranges in expression from a lingual groove to a pronounced cingulum. Hlusko’s (2002) study found that the interconulus in a population of Papio hamadryas from the Southwest National Primate Research Center has increasing expression from M1 to M3, an example of metameric variation. Our new study examined the molars of Papio (n=42) and Macaca (n=136) individuals from three museum skeletal collections for variation in the expression of the interconulus. Because the interconulus is a continuously varying trait, a standard of five discrete categories of expression (score 1-5; Hlusko 2002) was used to quantify the trait. The Papio individuals did not demonstrate statistically significant metameric variation in the expression of the interconulus. However, the Macaca sample did demonstrate significant metameric variation with mean scores of M1=1.12, M2=1.47 and M3=1.75. Assessment of mean expression scores at the species and subspecies level suggests that ordered metameric variation may occur in some taxonomic units and not others. Metameric variation is found in numerous parts of the metazoan body plan, from body segments, to sets of appendages, to the vertebral column. Our project aims to characterize the metameric variation seen in the Old World Monkey dentition, ultimately contributing to a more general understanding of the role that metameric variation has played and continues to play in primate evolution.
This study was funded by the National Science Foundation, grant number BCS-0616308.