Chewing function and feeding adaptations in early Palaeogene mammals with quadritubercular molars

四疣磨牙早期古近纪哺乳动物的咀嚼功能和摄食适应

• 批准号: 322948278
• 负责人: Professor Dr. Thomas Martin
• 金额: --
• 依托单位: Abteilung Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/322948278?language=en
• 关键词: Chewing; function; feeding; adaptations; early

A crucial step in early Palaeogene mammal evolution was the origin of the quadritubercular molar. The addition of a fourth cusp (hypocone) at the upper molar was a first shift from the basal tribosphenic pattern to molars with enlarged occlusal surface and increased grinding and crushing function. This made the utilisation of a wider array of food sources possible, especially of tough plant material and contributed essentially to the great success of the mammals in colonizing virtually all kinds of environments. However, up to now there are virtually no studies that have investigated the functional implications of this fundamental reorganisation of the mammalian molars. Especially, there is a lack of quantifying studies that demonstrate the efficiency of mastication. The project aims to compare the functional patterns of the different basal quadritubcercular molar constructions of early Palaeogene mammals in order to figure out similarities and differences. An important goal is the virtual simulation of the mastication cycle with the OFA-software which has been especially designed for that purpose. With the OFA for the first time functional contact areas and cutting edges of the molar occlusal surface can be visualized and quantified based on µCT-3D models. Additionally, micro-texture analyses that will be conducted with the µ-surf high resolution confocal microscope provide information on the diet. In our study we will test dietary adaptations of various Paleocene mammal groups (e.g. Macroscelidea, Plesiadapiformes, condylarths) that have been postulated earlier based on traditional parameters (e.g. tooth crown morphology), in order to better understand their role in the post-Cretaceous ecosystems. We expect fundamental new insights into the first phase of differentiation of the tribosphenic molar that initiated the great differentiation and unparalleled success of mammals in Cenozoic ecosystems.

早期古近纪哺乳动物进化的关键一步是四瘤臼齿的起源。在上磨牙处增加第四个尖牙（下锥体）是磨牙从基底摩擦型向增大的咬合面和增强的磨碎功能的第一次转变。这使得利用更广泛的食物来源成为可能，特别是坚韧的植物材料，并从根本上促成了哺乳动物在几乎各种环境中殖民的巨大成功。然而，到目前为止，几乎没有研究调查了哺乳动物磨牙的这种基本重组的功能含义。特别是，缺乏量化的研究来证明咀嚼的效率。本项目旨在比较古近纪早期哺乳动物不同基底四圆磨牙结构的功能模式，找出其异同点。一个重要的目标是用专门为此目的设计的ofa软件对咀嚼周期进行虚拟模拟。利用OFA首次可以基于微CT-3D模型可视化和量化磨牙咬合表面的功能接触区域和切割边缘。此外，将使用μ -surf高分辨率共聚焦显微镜进行微观纹理分析，以提供有关饮食的信息。在我们的研究中，我们将测试各种古新世哺乳动物群体的饮食适应性，这些群体（如巨壳类、蛇颈类、髁骨类）是早期基于传统参数（如齿冠形态）假设的，以便更好地了解它们在后白垩纪生态系统中的作用。我们期待对摩擦生磨牙分化的第一阶段有根本性的新见解，这一阶段开启了新生代生态系统中哺乳动物的巨大分化和无与伦比的成功。