Anthropology Theses and Dissertations

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Browsing Anthropology Theses and Dissertations by Author "Anderson, Monya"

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    Functional Morphology, Variation, and Niche Separation in the Large-Bodied Fossil Colobines
    (University of Oregon, 2019-09-18) Anderson, Monya; Frost, Stephen
    Colobines are ecological referents that can be used to assess and reconstruct paleoenvironmental conditions. Colobine taxa discussed here include Paracolobus mutiwa, P. Cercopithecoides williamsi, C. kimeui, and Rhinocolobus turkanensis. All of these taxa except for R. turkanensis display postcranial adaptations consistent with terrestrial locomotion in contrast to their exclusively arboreal African counterparts. At sites like these of the Upper Burgi Member of Koobi Fora, these four large colobines, up to four species of hominins, and three large-bodied cercopithecine taxa are known. This level of sympatry in primate communities is unmatched in modern habitats emphasizing the importance of niche separation for understanding diversity in the fossil record. The descriptions of two previously undescribed specimens: P. mutiwa specimen KNM-WT 16827 and the informally designated P. mutiwa specimen L895-1are presented here with detailed qualitative and quantitative postcranial analyses. Postcranial measurements from fossil colobines, fossil cercopithecines, and a large extant sample for comparative purposes. Measurements include 112 linear metrics and 54 functional indices. Body mass estimates for the fossil descriptions were calculated based on published equations for postcranial estimation. Dietary proxies for the fossil taxa are based on dental morphology and taken from the literature. Substrate preference is estimated using qualitative description of skeletal elements, quantitative comparison to extant taxa, and observational data of substrate use of extant species. Paracolobus mutiwa specimen KNM-WT 16827 shows postcranial morphologies consistent with terrestriality distinct from Cercopithecoides and Theropithecus and is distinct from P. chemeroni to a degree warranting generic reassessment of the species. Specimen L895-1 shows postcranial morphology consistent with terrestriality, is distinct from other contemporaneous cercopithecids, and is most similar in size and morphology to P. mutiwa. The niche separation analyses show C. williamsi to be the most terrestrial of the large colobines with the largest consumption of leaves. P. mutiwa overlaps with C. williamsi in size, but is less terrestrial and R. turkanensis is the least. There is also clear separation among the large colobines and Theropithecus in diet and substrate use. The sympatry and diversity of these large-bodied colobines suggests a much more diverse and dynamic primate environment than seen in East Africa today.