Doctoral Dissertation: A Comparative Analysis of Femur Morphology in Australopithecus afarensis: Implications for the Evolution of Bipedal Locomotion

本项目主要研究非洲东部上新世（约3.6-3.0 Ma）早期人科物种南方古猿阿法种（Australopithecus afarensis）的股骨近端。在过去的十年里，几个新的股骨近端化石标本在埃塞俄比亚的哈达尔被发现，那里是著名的“露西”骨架的所在地。合并后的阿法南方古猿股骨近端标本现在有15个主要成年标本，其中一些将在本研究中首次描述。能够利用如此庞大的单一解剖元素化石样本来量化化石物种的大小和形状变化是不寻常的。关于早期人类及其运动策略的几个重要问题将利用这个相对较大的化石样本进行研究。阿法古猿近端股骨的大小和形状变化程度将被评估，以确定它是否与其他类人猿具有可比性，因为如果包含阿法古猿的化石代表一个单一的物种，采用单一的运动模式（两足行走），那么它应该是。阿法种古猿近端股骨的形状将与现代人类、类人猿和其他早期人类进行比较，以确定具有共同运动策略的群体（如两足动物和四足动物）之间的共同特征。最后，我们将以一种新颖的方式探讨股骨的特征，这些特征被认为是适应双足运动的。系统发育方法将用于检查股骨特征从假设的共同（非双足）祖先到双足后代的变化模式。综合分析将有助于更好地理解南方古猿阿法种的股骨近端，以及股骨近端特征的变化，因为它们与两足行走的进化有关。这项研究将为非洲早期人类进化和适应的图景增添重要的新数据。除了学术兴趣之外，强调埃塞俄比亚化石对人类进化研究重要性的研究有助于国际社会认识到埃塞俄比亚对实地和实验室研究的重要性，并有助于创造当地的研究和培训机会。作为博士论文研究改进奖，该奖项还将为学生建立强大的独立研究生涯提供支持。

This project focuses on the proximal femur of the early hominin species Australopithecus afarensis from the Pliocene of eastern Africa (ca. 3.6-3.0 Ma). During the last decade, several new fossil specimens of the proximal femur have been recovered at Hadar, Ethiopia, home of the well-known "Lucy" skeleton. The combined A. afarensis proximal femur sample now numbers 15 primarily adult specimens, some of which will be described for the first time in this study. It is unusual to be able to draw on such a large fossil sample of a single anatomical element to quantify size and shape variation in a fossil species. Several significant questions about early hominins and their locomotor strategies will be investigated using this relatively large fossil sample. The degree of size and shape variation in the A. afarensis proximal femur will be assessed to determine whether it is comparable to that of other hominoids, as it should be if the fossils comprising A. afarensis represent a single species practicing a single mode of locomotion (bipedal walking). The shape of the A. afarensis proximal femur will be compared to that of recent humans, apes and other early hominins in order to identify shared features among groups with shared locomotor strategies, such as bipeds and quadrupeds. Finally, features of the femur that have been argued to be adaptations to bipedal locomotion will be explored in a novel way. A phylogenetic method will be used to examine the pattern of change in femoral features from a hypothetical common (non-bipedal) ancestor to bipedal descendants. The combined analyses will contribute to a better understanding of the proximal femur of A. afarensis, and of the variation in features of the proximal femur as they relate to the evolution of bipedal walking. This research will add important new data to the picture of early hominin evolution and adaptation in Africa. Beyond its intellectual interest, research highlighting the importance of Ethiopian fossils for the study of human evolution contributes to international awareness of the importance of Ethiopia to field and laboratory research, and helps to create local research and training opportunities. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a student to establish a strong independent research career.