Department of Biology, Georgia Southern University, PO Box 8042-1, Statesboro, GA 30460, USA.
Department of Biology, Georgia Southern University, PO Box 8042-1, Statesboro, GA 30460, USA
J Exp Biol. 2018 Dec 12;221(Pt 24):jeb185975. doi: 10.1242/jeb.185975.
Recent work indicates that bipedal posture in lizards is advantageous during obstacle negotiation. However, little is known about how bipedalism occurs beyond a lizard's acceleratory threshold. Furthermore, no study to date has examined the effects of forelimb position on the body center of mass (BCoM) in the context of bipedalism. This study quantified the frequency of bipedalism when sprinting with versus without an obstacle at 0.8 m from the start of a sprint. Forelimb positions were quantified during bipedal running at the start of a sprint and when crossing an obstacle. Two species with contrasting body forms (and thus different BCoM) were studied ( and ) to assess potential variation due to body plan and obstacle-crossing behavior. No significant difference in frequency of bipedalism was observed in with or without an obstacle. However, primarily used a bipedal posture when sprinting. Forelimb positions were variable in and stereotyped in Caudal extension of the forelimbs helped shift the BCoM posteriorly and transition to, or maintain, a bipedal posture in , but not in The posterior shift in BCoM, aided by more caudally placed forelimbs, helps raise the trunk from the ground, regardless of obstacle presence. The body plan, specifically the length of the trunk and tail, and forelimb position work together with acceleration to shift the BCoM posteriorly to transition to a bipedal posture. Thus, species exhibit morphological and behavioral adjustments to transition to and maintain facultative bipedalism while sprinting.
最近的研究表明，蜥蜴在障碍物跨越时采用双足姿势是有利的。然而，对于蜥蜴超越加速度阈值后如何进行双足运动，我们知之甚少。此外，迄今为止，没有研究在双足运动的背景下检查前肢位置对身体质心（BCoM）的影响。本研究量化了在距离冲刺起点 0.8 m 处有/无障碍物时冲刺时双足行走的频率。在冲刺开始和跨越障碍物时量化了前肢的位置。研究了两种具有不同身体形态（因此 BCoM 不同）的物种（和），以评估由于身体形态和障碍物跨越行为而产生的潜在变化。在有/无障碍物的情况下，没有观察到 双足行走频率的显著差异。然而， 主要在冲刺时采用双足姿势。 的前肢位置在 中变化，在 中刻板。前肢的后伸有助于将 BCoM 向后移动，并在 中过渡到或维持双足姿势，但在 中则不然。BCoM 的向后移动，得益于更靠后的前肢，有助于将躯干从地面抬起，无论是否存在障碍物。身体形态，特别是躯干和尾巴的长度以及前肢的位置，与加速度一起共同作用，将 BCoM 向后移动以过渡到双足姿势。因此，物种表现出形态和行为上的调整，以过渡到并维持在冲刺时的兼性双足行走。
