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

计算机辅助工程（CAE）越来越多地应用于古脊椎动物学。在软件SIMM®中对复杂的肌肉骨骼系统进行了非常详细的建模，并在NASTRAN中使用CAD生命重建对整个灭绝动物进行了动力学/动态建模。NASTRAN提供数据，如质心位置，关节扭矩，身体部位或整个动物的动能和势能，并允许优化模拟运动和运动周期，以最小的能量消耗。SIMM允许详细的3D肌肉重建，预测力臂，肌腱长度和不同姿势的单个肌肉的其他因素。我们将结合联合收割机SIMM建模与新的和现有的NASTRAN模型的第一次模拟运动和饲养的两个代表蜥脚类恐龙。这允许在复杂运动上导出结果，并显著提高每种建模方法的质量和细节水平。模型将基于保存完好的个体的3D数字骨骼支架。将根据NASTRAN中导出的数据选择分析的姿势。建模将以准静态方法进行（即，站立中期、最大肢体前伸和后缩、直立双足姿势）。我们将集中讨论主龙M.尾股肌驱动的后肢回缩系统，和哺乳动物的条件下，其中几个肌肉与短力矩臂。我们还将模拟蜥脚类动物前肢的生物力学与现存动物（大象和长颈鹿）的生物力学进行比较，以研究非常低（梁龙）或非常高（长颈鹿/腕龙）的肢体长度比如何影响运动。

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.