The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Primate cranial diversity: comparisons among the major primate radiations contradict larger and more general trends


1Department of Anatomical Sciences, Stony Brook University, 2Department of Anthropology, Hunter College of the City University of New York, 3Department of Anthropology, Graduate Center of the City University of New York, 4NYCEP, New York Consortium in Evolutionary Primatology, 5Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University

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Previous studies of primate cranial anatomy have noted a number of trends in primate cranial evolution. For example, it has long been suggested that primate facial characteristics, particularly skull, snout, and palate length, scale with positive allometry throughout Order Primates. However, less attention has been paid to whether these general trends differ among the major primate radiations (lemuroids, lorisoids, platyrrhines, cercopithecoids, and hominoids) within the order. The factors driving cranial diversity within a given radiation may differ from those driving cranial diversity within another, and these differences may be masked by the appearance of overall primate trends.

In this study, we examine cranial diversity within the major primate radiations, first individually and then compared with each other as well as with the general trends seen across the order. We use 3-D geometrics on 18 cranial landmarks to capture cranial shape in 66 genera of living primates. Contrary to popular belief, facial dimensions such as skull, snout and palate length do not scale with positive allometry across all primates; lemuroids and lorisoids show no significant allometric relationship between these measures and size. Instead, cranial base flexion, relative orbit size, and relative cranial volume are the most obvious features correlated with size among strepsirrhines. Thus, the apparent relationship between facial dimensions and body size in primates is the result of the strong correlation between these features in anthropoid primates. One may speculate that this relationship is the result of the cranial reorganization that took place during anthropoid origins.

This study was supported by the L.S.B. Leakey Foundation.

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