The Evolution of Exudativory in Primates

Part of the series Developments in Primatology: Progress and Prospects pp 169-185


Exudativory and Primate Skull Form

  • Matthew J. RavosaAffiliated withDepartment of Pathology and Anatomical Sciences, University of Missouri School of Medicine
  • , Russell T. Hogg
  • , Christopher J. Vinyard

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We review comparative and experimental research ­regarding the musculoskeletal correlates of exudativory in primates, providing novel data on: cranial ontogeny and scaling in galagos, macroscale tests of symphyseal joint performance in platyrrhines, and histology of enamel prism organization in the anterior dentition of callitrichids.

In galagos, derived configurations of jaw-joint position and jaw-muscle mechanical advantage in Otolemur and Euoticus appear to facilitate increased gape during scraping or gouging behaviors. Due to the lack of greater robusticity of load-resisting mandibular elements in Otolemur and Euoticus, there is little evidence to suggest that exudativory in galagos results in higher masticatory stresses. Compared to tamarins such as Saguinus, the marmoset Callithrix has canine enamel with a much higher degree of decussation. However, simulated jaw loading suggests a reduced ability to withstand external forces in the marmoset symphysis. The contrast between increased load-resistance ability in the anterior dentition versus relatively reduced symphyseal strength suggests both a potentially complex loading environment during gouging and a mosaic pattern of craniodental adaptations to this derived feeding behavior.

As primate exudativory involves different behavioral strategies to obtain gums and sap, it is not surprising that there is some discordance among the comparative evidence regarding the impact of anterior dental loading on masticatory elements. This is compounded by the fact that gouging and scraping are critical adaptations in some taxa and only seasonally important for others. Indeed, the ecomorphological­ significance of seasonality in feeding behaviors remains poorly understood, and this negatively affects analyses of the impact of fallback foods on skull form in living and fossil primates.