VERTEBRAL CORRELATES OF TAIL USE IN SUSPENSORY ATELINES |
J. E. Turnquist1; M. D. Rose2; D. Schmitt3 and P. Lemelin4
1UPR - Med Sch & CPRC Museum, Department of Anatomy and Caribbean Primate Research Center Museum, University of Puerto Rico Medical Sciences Campus, P.O. Box 365067, San Juan, PR, 00936-5067, USA, 2Radiology Department, University of Medicine and Dentistry of New Jersey - New Jersey Medical School, 3Biological Anthropology and Anatomy Department, Duke University, 4Anatomy Division, Faculty of Medicine and Dentistry, University of Alberta |
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| The interpretation of behavior in fossil primates depends largely on our ability to identify reliable morphological correlates, often from comparing closely related species. Comparisons of prehensile tail anatomy and use in two closely related atelines provide such an opportunity. Previous behavioral (Turnquist et al., 1999) and muscular (Lemelin, 1995) studies have identified important differences in the proximal tail segment between Ateles and Lagothrix. The current study examines vertebral morphology at the base of the tail and correlates skeletal features with behavioral and myological differences previously reported. Results show the proximal tail segment of Ateles (N=20) is significantly (two-tailed T-test, p<0.001) longer, contains more numerous, relatively shorter elements, and has vertebrae with relatively wider transverse processes compared to Lagothrix (N=20). Furthermore, the sacro-caudal articulation angle is significantly more acute in Ateles, imparting greater extension to the base of the tail. These differences in proximal tail vertebral anatomy correlate well with previously described behavioral and myological differences in these two genera, i.e., greater tail mobility and extension capability during brachiation, with less lateral sway of the body, and more extensive sacroiliac origins of some caudal muscles in Ateles versus Lagothrix. This study of the prehensile tail of two large-bodied atelines clearly links differences in behavior and skeletal morphology and could help infer prehensile tail use in fossil atelines, e.g., Protopithecus and Caipora. [Supported by NSF-SBR-9222526 and RCMI-RR-03051] |
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