Evolution of pelvis types in basal dinosaurs

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The pelvis is of great functional importance in tetrapods in supporting a large part of the body weight, providing a rigid connection between the hindlimbs and the vertebral column, and providing insertion areas for important limb muscles. Three pelvic types are distinguished in dinosaurs, referring to a cranial (propubic), ventral (mesopubic), or caudal (opisthopubic) orientation of the pubis. The development of these different pelvic shapes from dinosauromorphs to dinosaurs could never be satisfyingly explained. Pelvis shapes in dinosauromorphs and basal dinosaurs will therefore be analyzed by the innovative technique of Finite Element Structure Synthesis (FESS), which allows precise identification of shape-forming mechanical influences on the pelvis. Thereby, different hypotheses about soft-tissue reconstructions and the distribution of mechanical stresses acting on the pelvis during rest, locomotion, and ventilation, can be tested. Extant crocodylians and birds will provide the basis for comparisons in an Extant Phylogenetic Bracket approach, and will be used for a validation of the novel technique of FESS prior to the analysis of dinosaurian pelves. The results will be discussed under the aspects of evolutionary history and functional morphology. This integrative approach will help to better understand the consequences of the development of different pelvis shapes in dinosaurs for their locomotion and ecology.