A new method to calculate limb phase from trackways reveals gaits of sauropod dinosaurs
A new method to calculate limb phase from trackways reveals gaits of sauropod dinosaurs
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DOI：
10.1016/j.cub.2022.02.012
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发表时间：
2022-04-11
期刊：
影响因子：
9.2
通讯作者：
Falkingham，Peter L.
中科院分区：
文献类型：
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作者：
Lallensack，Jens N.;Falkingham，Peter L.
肢体阶段，即四足运动中的脚步时间，描述了小跑和步态等常见步态，1,2被广泛认为很难甚至不可能估计已灭绝的四足动物。3-5我们在这里提出了一种全新的方法，可以根据长轨迹的变化模式来估计肢体阶段。该方法在现代哺乳动物的轨迹上进行了测试，其中的估计值通常与实际使用的肢体阶段非常吻合。然后，我们根据美国阿肯色州下白垩纪的三个长轨迹估计了巨型宽口径蜥脚类恐龙的肢体阶段。6,7 由于缺乏现代类似物，最大体型的步态选择引起了相当大的兴趣。与之前的假设相反，8,9我们的估计表明横向序列对角对联行走，其中对角肢体对（例如右后和左前）的脚步在时间上比身体同一侧的脚步（例如右后和右前）在时间上更密切相关。这种步态选择可以实现高效行走，同时在整个步态周期中保持对角肢体支撑，这对于巨型、宽规格的田径运动员来说非常重要。10肢体阶段的估计可能有助于限制其他步态参数、身体尺寸和形状，以及最终潜在的田径运动员分类群。
Limb phase, the timing of the footfalls in quadrupedal locomotion that describes common gaits such as the trot and the pace gait,1,2is widely believed to be difficult or even impossible to estimate for extinct tetrapods.3–5We here present a fundamentally new approach that allows for estimating limb phase based on variation patterns in long trackways. The approach is tested on trackways of modern mammals, where the estimates generally correspond well with the actually employed limb phase. We then estimate limb phases of giant wide-gauged sauropod dinosaurs based on three long trackways from the Lower Cretaceous of Arkansas, US.6,7Gait selection at the largest body sizes is of considerable interest given the lack of modern analogs. Contrary to previous assumptions,8,9our estimates suggest lateral sequence diagonal couplet walks, in which the footfalls of the diagonal limb pairs (e.g., right hind and left fore) are more closely related in time than those of the same side of the body (e.g., right hind and right fore). Such a gait selection allows for efficient walking while maintaining diagonal limb support throughout the step cycle, which is important for a giant, wide-gauged trackmaker.10Estimations of limb phase may help to constrain other gait parameters, body size and shape, and, finally, potential trackmaker taxa.