Chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla) both knuckle-walk in adulthood but are known to develop their locomotor strategies differently. Using dentally defined age-groups of both Pan and Gorilla and behavioral data from the literature, this study presents an internal trabecular bone approach to better understand the morphological ontogeny of knuckle-walking in these taxa. Capitate and third metacarpal bones were scanned by μCT at 23-43 μm resolution with scaled volumes of interest placed centrally within the head of the capitate and base of the third metacarpal. Trabecular measures related to activity level (size-adjusted bone volume/total volume, trabecular number, and bone surface area/bone volume) met expectations of decreasing through ontogeny in both taxa. Degree of anisotropy did not show statistical support for predicted species differences, but this may be due to the sample size as observed changes through ontogeny reflect expected trends in the capitate. Analyses of principal trabecular orientation corroborated known behavioral differences related to variation of hand use in these taxa, but only Pan showed directional patterning associated with suggested wrist posture. Assessment of allometry showed that the trabecular bone of larger animals is characterized by fewer and thinner trabeculae relative to bone size. In combination, these findings confirm the efficacy of trabecular bone in reflecting locomotor ontogeny differences between closely related taxa. These techniques show promise for use within the hominin fossil record, particularly for taxa hypothesized to be arboreal in some capacity.

中文翻译：

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小黑猩猩（盘古猿）和大猩猩（大猩猩大猩猩）的头突和掌骨的小梁结构。

黑猩猩（Pan troglodytes）和大猩猩（Gorilla gorilla）都成年后会走路，但众所周知，它们的运动策略有所不同。利用牙科定义的Pan和Gorilla的年龄组以及来自文献的行为数据，本研究提出了一种内部小梁骨入路，以更好地了解这些类群中的指关节行走的形态学。用μCT在23-43μm的分辨率下扫描头状骨和第三掌骨，将感兴趣的标称体积置于头状骨的头部和第三掌骨基部的中央。与活动水平（大小调整后的骨体积/总体积，小梁数目和骨表面积/骨体积）相关的骨小梁测量值符合两个类群中通过个体发育而减少的预期。各向异性程度并未显示出对所预测物种差异的统计支持，但这可能是由于样本量所致，因为通过个体发生所观察到的变化反映了人头动物的预期趋势。对主要小梁取向的分析证实了这些类群中与手使用变化有关的已知行为差异，但只有Pan显示了与建议的手腕姿势有关的方向性图案。异体测量的评估表明，较大动物的小梁骨的特点是相对于骨骼大小，小梁的数量较少且较细。综合起来，这些发现证实了小梁骨在反映密切相关的类群之间运动个体发育差异方面的功效。这些技术显示了在人化石记录中使用的希望，特别是对于假设以某种能力为树栖类的分类单元。