Jayne BC, Irschick DJ
Department of Biological Sciences, PO Box 210006, University of Cincinnati, Cincinnati, OH 45221-0006, USA.
J Exp Biol. 1999 Jan;202 (Pt 2):143-59. doi: 10.1242/jeb.202.2.143.
Lizards commonly move on steep inclines in nature, but no previous studies have investigated whether the kinematics of the limbs of lizards differ on inclined surfaces compared with level surfaces. Therefore, we examined how the kinematics of the hindlimb were affected by both incline (downhill 30 degrees, level and uphill 30 degrees) and different speeds of steady locomotion (50-250 cm s-1) in the morphologically generalized iguanian lizard Dipsosaurus dorsalis. On the uphill surface, the strides of lizards were shorter and quicker than those at a similar speed on the level and downhill surfaces. A multivariate analysis revealed that the kinematics of locomotion on all three inclines were distinct, but several kinematic features of locomotion on the downhill surface were especially unique. For example, downhill locomotion had the lowest angular excursions of femur rotation, and the knee and ankle were flexed more at footfall which contributed to a very low hip height. For D. dorsalis, changes in knee and ankle angles on the uphill surface were similar to those described previously for mammals moving up inclines, despite fundamental differences in limb posture between most mammals and lizards. Several features of the kinematics of D. dorsalis suggest that a sprawling limb enhances the ability to move on inclines.
蜥蜴在自然界中通常会在陡峭的斜坡上移动，但之前没有研究调查过蜥蜴四肢的运动学在倾斜表面与水平表面上是否存在差异。因此，我们研究了形态学上具有代表性的鬣蜥科蜥蜴背鳞帆蜥（Dipsosaurus dorsalis）的后肢运动学是如何受到倾斜度（下坡30度、水平和上坡30度）以及不同稳定运动速度（50 - 250厘米/秒）影响的。在上坡表面，蜥蜴的步幅比在水平和下坡表面上以相似速度移动时更短且更快。多变量分析表明，在所有三种倾斜度上的运动学都是不同的，但下坡表面运动的几个运动学特征尤其独特。例如，下坡运动时股骨旋转的角度偏移最小，并且在脚着地时膝盖和脚踝弯曲得更多，这导致臀部高度非常低。对于背鳞帆蜥来说，上坡表面膝盖和脚踝角度的变化与之前描述的哺乳动物上坡时的变化相似，尽管大多数哺乳动物和蜥蜴的肢体姿势存在根本差异。背鳞帆蜥运动学的几个特征表明， sprawled肢体增强了在斜坡上移动的能力。 （注：原文中“sprawling limb”直译为“ sprawled肢体”，可能需要结合更多生物学背景知识来准确理解其在蜥蜴肢体结构方面的含义，这里暂按字面翻译。）
