Klinkhamer Ada J, Mallison Heinrich, Poropat Stephen F, Sinapius George H K, Wroe Stephen
Function, Evolution, and Anatomy Research Lab, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia.
Australian Age of Dinosaurs Museum of Natural History, Winton, Queenland, Australia.
Anat Rec (Hoboken). 2018 Dec;301(12):2145-2163. doi: 10.1002/ar.23950. Epub 2018 Oct 19.
The biomechanical constraints for life at massive size can be directly observed in the evolutionary history of sauropodomorph dinosaurs. Members of this lineage underwent a number of major postural transitions as they increased in size from relatively small bipedal dinosaurs to massive titanosaurs that include the largest terrestrial animals of all time. To better understand the impact of gigantic size on the biomechanics of sauropods, we used three-dimensional musculoskeletal modeling to investigate how hind limb musculature was affected, first by the development of a quadrupedal stance from a bipedal one, and later in the transition from a narrow-gauge to a wide-gauge stance. Muscle moment arms were measured in four sauropodomorph taxa: the bipedal basal sauropodomorph Plateosaurus engelhardti, the narrow-gauge diplodocid Diplodocus carnegii, the titanosauriform Giraffatitan brancai, and the wide-gauge titanosaur Diamantinasaurus matildae. In Plateosaurus, low moment arm leverage in the hip extensors and knee flexors and extensors was observed suggesting high-velocity movement for fast locomotion. A reduction in hip extensor leverage in Diamantinasaurus was found which suggests a reduced role for the hind limb in forward propulsion in titanosaurs. An increase in overall hip adductor leverage and leverage of adductors 1 and 2 in Diamantinasaurus, compared with other taxa studied, might relate to the development of a wide-gauge stance. High knee flexor-extensor leverage in Giraffatitan but not Diamantinasaurus partially refutes the idea that broader femoral condyles in titanosauriforms increased knee torque production capabilities. Sauropodomorph postural changes clearly had an impact on the function and leverage of hind limb muscles. Anat Rec, 301:2145-2163, 2018. © 2018 Wiley Periodicals, Inc.
在蜥脚形亚目恐龙的进化历史中，可以直接观察到大体型生物生存的生物力学限制。随着体型从相对较小的双足恐龙增加到有史以来最大的陆地动物——巨型泰坦龙，这一谱系的成员经历了多次重大的姿势转变。为了更好地理解巨大体型对蜥脚类动物生物力学的影响，我们使用三维肌肉骨骼建模来研究后肢肌肉组织是如何受到影响的，首先是从双足姿势发展为四足姿势，随后是从窄步幅姿势转变为宽步幅姿势。在四个蜥脚形亚目分类单元中测量了肌肉力臂：双足的基础蜥脚形亚目恩氏板龙、窄步幅的梁龙科卡内基梁龙、泰坦巨龙类布氏腕龙，以及宽步幅的泰坦巨龙马氏迪亚曼蒂纳龙。在板龙中，观察到髋部伸肌以及膝部屈肌和伸肌的力臂杠杆作用较低，这表明其具有高速运动以实现快速移动的能力。在迪亚曼蒂纳龙中发现髋部伸肌杠杆作用降低，这表明后肢在泰坦巨龙向前推进中的作用减小。与其他研究的分类单元相比，迪亚曼蒂纳龙整体髋部内收肌杠杆作用以及内收肌1和内收肌2的杠杆作用增加，可能与宽步幅姿势的发展有关。腕龙的膝部屈肌 - 伸肌杠杆作用较高，但迪亚曼蒂纳龙并非如此，这部分驳斥了泰坦巨龙类更宽的股骨髁增加了膝部扭矩产生能力的观点。蜥脚形亚目的姿势变化显然对后肢肌肉的功能和杠杆作用产生了影响。《解剖学记录》，301:2145 - 2163，2018年。© 2018威利期刊公司。
