Franz Theresa M, Demes Brigitte, Carlson Kristian J
Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA.
J Hum Evol. 2005 Feb;48(2):199-217. doi: 10.1016/j.jhevol.2004.11.004. Epub 2005 Jan 12.
Aspects of gait mechanics of two lemurid species were explored experimentally. Substrate reaction forces were recorded for three animals each of L. catta and E. fulvus walking and running at voluntary speeds either on a wooden runway with an integrated force platform or on elevated pole supports with a section attached to the force platform. The average height of the back over these substrates and fluctuations in this height were evaluated using video-analysis. Animals preferred walking gaits and lower speeds on the poles, and gallops and higher speeds on the ground. At overlapping speeds, few adjustments to substrate types were identified. Hind limb peak forces are usually lower on the poles than on the ground, and the caudal back is closer to the substrate. This suggests that greater hind limb flexion and reduced limb stiffness occurred on the poles. The support phases for both limbs at higher speeds are slightly elongated on the poles. Forelimb peak forces are not lower, and the trajectory of the caudal back does not follow a smoother path, i.e., not all elements of a compliant gait are present on the simulated arboreal substrates. The horizontal, rigid poles, offered as substitutes for branchlike supports in the natural habitat, may not pose enough of a challenge to require more substantial gait adjustments. Across substrates, forelimb peak forces are generally lower than hind limb peak forces. The interlimb force distribution is similar to that of most other primates with more even limb lengths. Walking gaits present a greater divergence in fore- and hind limb forces than galloping gaits, which are associated with higher forces. The more arboreal E. fulvus has higher forelimb forces than the more terrestrial L. catta, unlike some anthropoid species in which the arborealists have lower forelimb forces than the terrestrialists. As in other primate and nonprimate quadrupeds, the major propulsive thrust comes from the hind limbs in both lemurs. While our data confirm certain aspects of primate gait mechanics (e.g., generally higher hind limb forces), they do not fully support the notion of greater limb compliance. Neither a compliant forelimb on branchlike supports, nor a negative correlation of forelimb force magnitudes with degree of arboreality were observed. Increasing forelimb-to-hind-limb-force-ratios with increasing speed and force magnitudes are also not expected under this paradigm.
对两种狐猴的步态力学方面进行了实验探索。记录了每只分别来自环尾狐猴（L. catta）和褐美狐猴（E. fulvus）的三只动物在集成测力平台的木制跑道上或连接到测力平台的高架杆支撑上以自主速度行走和奔跑时的地面反作用力。使用视频分析评估这些动物在这些基质上背部的平均高度以及该高度的波动情况。动物在杆子上更喜欢行走步态和较低速度，而在地面上更喜欢疾驰和较高速度。在重叠速度下，几乎没有发现对基质类型的调整。后肢峰值力在杆子上通常比在地面上低，并且尾部背部更靠近基质。这表明在杆子上后肢弯曲更大且肢体刚度降低。在较高速度下，两只肢体在杆子上的支撑阶段略有延长。前肢峰值力并不更低，并且尾部背部的轨迹并没有遵循更平滑的路径，即，在模拟的树栖基质上并没有出现顺应性步态的所有要素。作为自然栖息地中树枝状支撑的替代品的水平刚性杆，可能没有带来足够的挑战以要求更实质性的步态调整。在不同基质上，前肢峰值力通常低于后肢峰值力。肢体间的力分布与大多数其他四肢长度更均匀的灵长类动物相似。行走步态在前肢和后肢力方面的差异比疾驰步态更大，疾驰步态与更高的力相关。与一些类人猿物种不同，在类人猿物种中树栖者的前肢力低于陆栖者，更多树栖的褐美狐猴比更多陆栖的环尾狐猴具有更高的前肢力。与其他灵长类和非灵长类四足动物一样，两种狐猴的主要推进推力都来自后肢。虽然我们的数据证实了灵长类步态力学的某些方面（例如，后肢力通常更高），但它们并不完全支持更大肢体顺应性的概念。在树枝状支撑上没有观察到顺应性前肢，也没有观察到前肢力大小与树栖程度之间的负相关。在这种范式下，也预计不会随着速度和力大小的增加而出现前肢与后肢力比增加的情况。
