Department of Musculoskeletal and Ageing Science, Institute of Life Course & Medical Sciences, Faculty of Health & Life Sciences, The W.H. Duncan Building, Liverpool, United Kingdom.
School of Archaeology, Classics and Egyptology, University of Liverpool, Liverpool, United Kingdom.
Folia Primatol (Basel). 2021;92(5-6):243-275. doi: 10.1159/000519723. Epub 2021 Sep 28.
The StW 573 skeleton of Australopithecus prometheus from Sterkfontein Member 2 is some 93% complete and thus by far the most complete member of that genus yet found. Firmly dated at 3.67 Ma, it is one of the earliest specimens of its genus. A crucial aspect of interpretation of locomotor behaviour from fossil remains is an understanding of the palaeoenvironment in which the individual lived and the manner in which it would have used it. While the value of this ecomorphological approach is largely accepted, it has not been widely used as a stable framework on which to build evolutionary biomechanical interpretations. Here, we collate the available evidence on StW 573's anatomy in order, as far as currently possible, to reconstruct what might have been this individual's realized and potential niche. We explore the concept of a common Australopithecus "bauplan" by comparing the morphology and ecological context of StW 573 to that of paenocontemporaneous australopiths including Australopithecus anamensis and KSD-VP-1/1 Australopithecus afarensis. Each was probably substantially arboreal and woodland-dwelling, relying substantially on arboreal resources. We use a hypothesis-driven approach, tested by: virtual experiments, in the case of extinct species; biomechanical analyses of the locomotor behaviour of living great ape species; and analogical experiments with human subjects. From these, we conclude that the habitual locomotor mode of all australopiths was upright bipedalism, whether on the ground or on branches. Some later australopiths such as Australopithecus sediba undoubtedly became more terrestrial, allowing sacrifice of arboreal stability in favour of manual dexterity. Indeed, modern humans retain arboreal climbing skills but have further sacrificed arboreal effectiveness for enhanced ability to sustain striding terrestrial bipedalism over much greater distances. We compare StW 573's locomotor adaptations to those of living great apes and protohominins, and agree with those earlier observers who suggest that the common panin-hominin last common ancestor was postcranially more like Gorilla than Pan.
南方古猿普罗米修斯的斯特克方丹 2 号标本是迄今为止最完整的南方古猿属标本，其骨骼完整度约为 93%。它被明确鉴定为 367 万年前的标本，是该属中最早的标本之一。从化石遗骸推断运动行为的一个关键方面是理解个体生活的古环境以及它可能使用该环境的方式。尽管这种生态形态学方法的价值已被广泛接受，但它尚未被广泛用作构建进化生物力学解释的稳定框架。在这里，我们整理了有关 StW 573 解剖结构的现有证据，以便尽可能地重建该个体的实际和潜在生态位。我们通过比较 StW 573 的形态和生态背景与同时代的其他南方古猿，包括南方古猿 anamensis 和 KSD-VP-1/1 南方古猿 afarensis，来探索共同的南方古猿“蓝图”概念。这些物种可能都大量地生活在树上和林地中，主要依赖于树栖资源。我们采用了一种假设驱动的方法，通过以下方法进行测试：对于已灭绝的物种，进行虚拟实验；对现生大型猿类的运动行为进行生物力学分析；以及在人类受试者中进行类比实验。由此，我们得出结论，所有南方古猿的习惯性运动模式都是直立两足行走，无论是在地面上还是在树枝上。后来的一些南方古猿，如南方古猿 sediba，无疑变得更加适应陆地生活，牺牲了树栖稳定性以提高手的灵巧性。事实上，现代人保留了树栖攀爬技能，但为了提高在更大距离上支撑跨步陆地两足行走的能力，进一步牺牲了树栖效率。我们将 StW 573 的运动适应与现生大型猿类和原始人类进行了比较，并同意那些早期的观察结果，即共同的人猿最近共同祖先在骨骼结构上更像大猩猩而不是黑猩猩。
