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.

古近纪早期哺乳动物进化的关键一步是四结节臼齿的起源。第四尖（hypocone）在上磨牙的增加是第一次从基础tribosphenic模式转移到磨牙扩大咬合面和增加研磨和破碎功能。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，并为哺乳动物在几乎所有类型的环境中殖民的巨大成功做出了重要贡献。然而，到目前为止，几乎没有研究已经调查了哺乳动物臼齿的这种根本性重组的功能影响。特别是，缺乏定量的研究，证明咀嚼的效率。该项目旨在比较古近纪早期哺乳动物不同基底四颈臼齿结构的功能模式，以找出相似性和差异。一个重要的目标是咀嚼周期的虚拟仿真与OFA软件，已专门为此目的而设计。借助OFA，首次可以基于µCT-3D模型对磨牙咬合面的功能接触区域和切削刃进行可视化和量化。此外，将使用µ-surf高分辨率共聚焦显微镜进行的微观纹理分析提供了有关饮食的信息。在我们的研究中，我们将测试饮食适应的各种古新世哺乳动物群体（如Macroscelidea，Plesiadapiformes，髁状突），已假定较早的传统参数（如牙冠形态）的基础上，为了更好地了解他们在后白垩纪生态系统中的作用。我们期待着对tribosphenic臼齿分化的第一阶段的基本新见解，该阶段启动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。