Sauropod CAE (Computer Aided Engineering): kinetic/dynamic and musculoskeletal modeling combined to quantify functional differences in comparison to mammals

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Computer Aided Engineering (CAE) is increasingly used in vertebrate paleontology. Both highly detailed modeling of complex musculoskeletal systems in the software SIMM®, and kinetic/dynamic modeling of entire extinct animals using CAD life reconstructions in NASTRAN have been conducted successfully. NASTRAN delivers data such as center of mass position, joint torques, kinetic and potential energy of body segments or the whole animal, and allows optimizing simulated motions and motion cycles for minimal energy use. SIMM allows detailed 3D muscle reconstructions, predicting moment arms, tendon length and other factors for individual muscles in varied poses. We will combine SIMM modeling with new and existing NASTRAN models for the first time by modeling locomotion and rearing of two representative sauropod dinosaurs. This allows deriving results on complex motions , and improving the quality and detail level of each modeling approach significantly. Models will be based on 3D digital skeletal mounts of well preserved individuals. The analyzed postures will be chosen based on data derived in NASTRAN. Modeling will be conducted in a quasi-static approach (i.e. at midstance, maximum limb pro- and retraction, upright bipedal pose). We will focus on the differences between the archosaur M. caudofemoralis driven hind limb retraction system, and the mammalian condition, in which several muscles with short moment arms are employed. We will also model the biomechanics of sauropod forelimbs compared to those of extant animals (elephants and giraffes), to investigate how very low (Diplodocus) or very high (Giraffatitan/Brachiosaurus) limb length ratios influences locomotion.