Dental function and dietary adaptations of hyracoid mammals

Hyracoids是一个起源于非洲的哺乳动物类群（非洲兽），在非洲、小亚细亚和南欧的古近纪和新近纪生态系统中发挥着重要作用。如今，在北方非洲和近东，它们的多样性减少到只有几只兔子大小的岩石栖息物种。早第三纪和晚第三纪时期，它们在北方非洲和邻近地区的哺乳动物群落中占主导地位，体型从老鼠到犀牛不等。这些巨大的蹄兔在北方非洲古群落（e。例如，在一个实施例中，法尤姆）的作用。在新第三纪，这一作用相继被有蹄类动物所取代。蹄兔也特别令人感兴趣，因为独立于有蹄哺乳动物（有蹄类动物），它们进化出的齿系与犀牛和马形动物的齿系惊人地相似，具有低冠牙齿。与犀牛相似，蹄兔的上颊齿拥有明显的W形外部切割边缘（外唇）。与犀牛和其他食草动物不同的是，蹄兔使用（今天仍然使用）这种外唇进行侧向食物摄取，而犀牛使用它们的门牙进行食物摄取。这表明蹄兔和有蹄类动物的齿系之间存在重要的功能差异，这可能导致了后来蹄兔的衰落和有蹄类动物的取代。与过去对有蹄类动物齿系功能的深入研究相比，蹄兔齿系功能的研究还很薄弱。我们的建议旨在缩小这一重要的知识差距，并大大有助于了解古近纪和新第三纪早期蹄兔在其古群落的古生态学。在DFG研究单位771中，我们开发了一个软件，用于灭绝哺乳动物咀嚼的虚拟重建，并根据定量数据研究牙齿功能的效率。咬合指纹分析仪（OFA）已成功地用于重建各种哺乳动物的咀嚼周期，并应应用于蹄兔牙列。该提案的目的是详细了解蹄兔咀嚼和评估其效率。将通过量化咀嚼周期中涉及的咬合面接触面积来进行效率估计。将从蹄兔获得的数据与从犀牛齿系获得的数据进行比较，以评价两组之间的效率差异。我们期望从该项目深入了解哺乳动物齿系功能的演变，灭绝的蹄兔的饮食偏好，它们在哺乳动物古群落中的生态作用，以及它们在新近纪的多样性下降和有蹄哺乳动物的替代。

Hyracoids are a mammalian group of African origin (Afrotheria) that played an important role in Paleogene and Neogene ecosystems of Africa, Asia Minor, and southern Europe. Nowadays their diversity is reduced to few rabbits sized rock dwelling species in northern Africa and the Near East. During the Paleogene and lower Neogene they were dominating herbivores in mammal communities of northern Africa and adjacent regions, ranging in size from mouse to rhinoceros. These giant hyraxes played in northern African palaeocommunities (e. g., Fayum) the role of megaherbivores. During the Neogene this role was successively taken over by ungulates. Hyraxes are also of particular interest, because independently from hoofed mammals (ungulates) they have evolved dentitions which are strikingly similar to those of rhinoceroses and equoids with low crowned teeth. Similar to rhinoceroses, the upper cheek teeth of hyraxes possess a pronounced W-shaped external cutting edge (ectoloph). Differing from rhinos and other herbivores, hyraxes used (and still use today) this ectoloph for lateral food ingestion, whereas rhinos use their front teeth for food intake. This indicates an important functional difference between hyrax and ungulate dentitions that possibly contributed to the later decline of hyraxes and their replacement by ungulates. In contrast to the function of ungulate dentitions that has been intensively investigated in the past, the function of hyrax dentitions is poorly studied so far. Our proposal aims to close this important gap of knowledge and to substantially contribute to the understanding of the paleoecology of Paleogene and early Neogene hyraxes in their paleocommunities. Within the DFG research unit 771 we have developed a software for virtual reconstruction of the mastication of extinct mammals and to study the efficiency of dental function based on quantitative data. The Occlusal Fingerprint Analyzer (OFA) has been successfully used for reconstructing the masticatory cycle of various mammalian groups and shall be applied to hyrax dentitions. Aim of the proposal is to gain detailed insight into hyrax mastication and to evaluate their efficiency. Efficiency estimation will be performed via a quantification of the contact areas of the occlusal surface that are involved during the chewing cycle. The data obtained from hyraxes will be compared with data from rhino dentitions for evaluating differences of efficiency between both groups. We expect from the project in-depth insight into the evolution of the function of mammalian dentitions, of dietary preferences of extinct hyraxes, their ecological role within the mammalian paleocommunities, and their decline in diversity during the Neogene and replacement by hoofed mammals.