Abstract：
Evolutionary analyses of joint kinematics and muscle mechanics suggest that, during cyclic behaviors, tetrapod feeding systems are optimized for precise application of forces over small displacements during chewing, whereas locomotor systems are more optimized for large and rapid joint excursions during walking and running. If this hypothesis is correct, then it stands to reason that other biomechanical variables in the feeding and locomotor systems should also reflect these divergent functions. We compared rhythmicity of cyclic jaw and limb movements in feeding and locomotor systems in 261 tetrapod species in a phylogenetic context. Accounting for potential confounding variables, our analyses reveal higher rhythmicity of cyclic movements of the limbs than of the jaw. Higher rhythmicity in the locomotor system corroborates a hypothesis of stronger optimization for energetic efficiency: deviation from the limbs\' natural frequency results in greater variability of center of mass movements and limb inertial changes, and therefore more work by limb muscles. Relatively lower rhythmicity in the feeding system may be a consequence of the necessity to prevent tooth breakage and wear, the greater complexity of coordination with tongue movements, and/or a greater emphasis on energy storage in elastic elements rather than the kinetics of limb movement.
摘要：
关节运动学和肌肉力学的进化分析表明，在循环行为期间，四足动物喂养系统进行了优化，以在咀嚼过程中的小位移上精确施加力，而运动系统更适合行走和跑步过程中的大型和快速关节运动。如果这个假设是正确的,那么它是有道理的，在喂养和运动系统的其他生物力学变量也应反映这些不同的功能。我们在系统发育背景下比较了261个四足动物物种的进食和运动系统中循环下颌和肢体运动的节律性。考虑潜在的混杂变量，我们的分析表明，四肢的周期性运动的节律性高于下颌。运动系统中更高的节律性证实了能量效率更优化的假设:与肢体固有频率的偏差导致质心运动和肢体惯性变化的更大可变性。因此，更多的工作是由四肢肌肉。喂养系统中相对较低的节律性可能是防止牙齿断裂和磨损的必要性的结果。舌头运动的协调更加复杂，和/或更强调弹性元件中的能量存储，而不是肢体运动的动力学。
