Expanding our horizons in understanding brain and dietary evolution in Primates and their kin

饮食的进化是灵长类起源过程的核心。所有关于灵长类起源的相互竞争的假设都有一个饮食组成部分：视觉捕食集中在对食虫的适应上;终端分支喂养涉及到树栖饮食生态位的扩大，包括更多的水果;以及抓取跳跃假说，它包含了早期灵长类进化中向更大的草食动物的转变。饮食对于理解灵长类动物大脑的进化具有特别重要的意义。构建这样的大脑需要获得高能量食物，同时获取这种广泛分散和不规则的食物（例如，水果）需要更大程度的加工能力。尽管对现代灵长类动物的分析支持了饮食在大脑进化中的重要作用，但它们必然会将灵长类动物的起源简化为一个单一的节点。化石记录表明，有许多谱系的茎灵长类动物，使它清楚地表明，这个故事要比这些研究所暗示的理想化版本复杂得多。虽然近年来有了长足的进步，但仍然有几个早期灵长类谱系没有定量的工作来估计饮食方面。这种不足的一个关键组成部分是，早期灵长类动物具有在现存灵长类动物中没有发现的适应模式，这意味着该命令的活体成员不足以重建这些群体的饮食模式。目前的研究将寻求填补这些空白，考虑更广泛的模式类群，并通过使用尖端的牙齿地形方法，以允许精确的量化牙齿的形式。这项研究还将寻求扩大可以收集的信息类型，并与灵长类动物大脑的早期进化进行比较。灵长类动物大脑大小进化中普遍存在的平行性的强有力证据意味着，仅限于活的分类群的研究将在重建所有灵长类动物共同祖先的大脑大小和形状方面受到限制。这强调了化石对理解灵长类动物大脑进化早期阶段的重要性。由于大脑不会自动化，即使是保存最完好的化石，其数据也仅限于保存在颅骨内表面的大脑印记（即，内模）。目前的研究将寻求使用几何形态测量和DiceCT方法来扩展可以从这种内模中提取的关于形状和功能变化的信息。 最终，这项研究的目标将是积累一个数据集，这将允许综合考虑饮食变化如何与大脑大小和形状的变化相一致（或不一致），使用一个系统发育框架，该框架包括灵长类动物的化石和现存成员，以及密切相关的群体。

The evolution of the diet is central to the process of primate origins. All of the competing scenarios for primate origins have a dietary component: visual predation focusing on adaptations for insectivory; terminal branch feeding involving an expansion of the arboreal dietary niche to include more fruit; and the grasp-leaping hypothesis, which incorporates a shift to greater herbivory in early primate evolution. Diet is of particular importance in understanding the evolution of the enlarged and complex primate brain. Building such a brain requires access to high energy food, while retrieving such broadly dispersed and irregularly available foodstuffs (e.g., fruit) requires greater degrees of processing power. Although analyses of modern primates have supported the important role of diet in brain evolution, they necessarily simplify the origin of primates down to a single node. The fossil record demonstrates that there were many lineages of stem primates, making it clear that the story is much more complex than the idealized version implied by such studies. Although there have been strides in recent years, there are still several lineages of early primates for which no quantitative work has been done to estimate aspects of diet. A critical component of this shortfall is that early primates have patterns of adaptations not found among living primates, meaning that living members of the order are insufficient models for reconstructing diet in those groups. The current study will seek to fill some of these gaps by considering a much broader range of model taxa and by using cutting edge dental topographic methods to allow for precise quantification of dental form. This study will also seek to expand the types of information that can be collected and compared with respect to the early evolution of the brain in primates. The strong evidence for rampant parallelism in primate brain size evolution implies that studies that are limited to living taxa will be constrained in reconstructing the size and shape of the brain in the common ancestor of all primates. This underscores the importance of fossils to an understanding of the early stages of primate brain evolution. Since the brain does not fossilize, the data available from even the best-preserved fossils is limited to the imprint of the brain preserved on the internal surface of the cranium (i.e., the endocast). The current study will seek to use geometric morphometric and DiceCT methods to expand the information about changing shape and function that can be extracted from such endocasts. Ultimately, the goal of this study will be to amass a dataset that will allow for a synthetic consideration of how shifting diets are aligned (or not) with changes in brain size and shape, using a phylogenetic framework that incorporates both fossil and extant members of Primates, and of closely related groups.