Chewing function and feeding adaptations in triconodont mammals

• Applicant: Professor Dr. Thomas Martin
• Subject Area: Palaeontology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 265535948

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.

• DFG Programme: Research Grants