Chewing function and feeding adaptations in triconodont mammals

茎类哺乳动物（哺乳动物）的多形磨牙模式是三齿状体，具有三个主要尖端的前后对齐。这种齿形模式是基础哺乳动物的特征，例如具有据称的食虫营养的morganucodonids。一方面，从这些基底三齿兽中，出现了具有臼齿尖反三角形模式的进化谱系，从而产生了具有摩擦齿的现代哺乳动物。这种三角形交替排列的齿尖是现代哺乳动物牙齿高度分化的原因。而准三齿兽谱系在没有三角剖分的情况下保持了三齿兽的形态，并进一步完善了三齿兽的形态。真齿兽是第一种通过上下牙齿的精确咬合而进化成食肉动物的哺乳动物。它们一直成功生存到白垩纪晚期，中生代最大的哺乳动物属于这一类群（重达15公斤的巨瘤猴）。利用我们DFG研究单位771开发的创新的咬合指纹分析仪软件工具，可以首次对三齿象的咀嚼周期进行三维建模。通过对咀嚼过程中牙齿接触面积的量化，可以估计各种牙齿和类型的效率。该项目的目的是通过高分辨率3D模型和咬合表面的条纹和显微纹理分析，分析从基底三齿兽的食虫牙列到原三齿兽的肉食性适应的功能转变。使用咬合指纹分析仪软件，咀嚼周期将首次建模。通过与现存哺乳动物牙齿的比较，将对食虫性和食肉性喂养适应性的假设进行检验。该项目的目的除了深入了解哺乳动物咀嚼的进化外，还旨在了解三齿兽在中生代脊椎动物群落中的作用。

The plesiomorphic molariform pattern of stem-mammals (mammaliaforms) is the triconodont condition, with an anterior-posterior alignment of the three main cusps. This molariform pattern characterizes basal mammaliaforms such as the morganucodontids with a purported insectivorous nutrition. From these basal triconodonts on one hand the evolutionary lineage with a reversed triangle pattern of molar cusps emerged, leading to modern mammals with tribosphenic teeth. This cusp arrangement of alternating triangles was predisposition for the highly differentiated dentitions of modern mammals. On the other hand, the eutriconodont lineage maintained the triconodont pattern without triangulation and further refined it. Eutriconodonts were the first mammals to develop a carnivorous adaptation by a precise occlusion of upper and lower teeth. They were successful up to the Late Cretaceous and the largest Mesozoic mammals belonged to this group (Repenomamus with up to 15 kg body mass). With the innovative Occlusal Fingerprint Analyser software tool that has been developed by our DFG research unit 771 the chewing cycle of triconodonts can be modeled three dimensionally for the first time. By a quantification of tooth contact areas during mastication the efficiency of the various tooth and types can be estimated. The aim of the project is to analyse the functional transformation from the insectivorous dentition of basal triconodonts to the carnivorous adaptation of Eutriconodonta by high resolution 3D models and a striation- and microtexture-analysis of the occlusal surfaces. Using the Occlusal Fingerprint Analyser software the mastication cycle will be modelled for the first time. Hypotheses on insectivrous and carnivorous feeding adaptations will be tested by comparison with dentitions of extant mammals. The aim of the project is besides an in-depth understanding of evolution of mastication in mammals an insight in the role of triconodonts in Mesozoic vertebrate communities.