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

该项目主要研究东非上新世(约3.6-3.0 Ma)早期人类物种南方古猿的股骨近端。在过去的十年里，在埃塞俄比亚的哈达尔发现了几个新的股骨近端化石样本，那里是著名的“露西”骨架的故乡。合并的阿法氏近端股骨样本现在有15个主要是成人样本，其中一些将在本研究中首次描述。能够利用单一解剖元素的如此大的化石样本来量化化石物种的大小和形状变化是不寻常的。利用这个相对较大的化石样本，将研究几个关于早期原始人及其运动策略的重要问题。将对阿法尔人股骨近端的大小和形状变化程度进行评估，以确定它是否与其他人形动物的大小和形状变化程度相当，如果构成阿法尔人的化石代表单一物种练习单一运动模式(两足行走)，就应该如此。阿法尔人股骨近端的形状将与现代人、猿类和其他早期原始人的形状进行比较，以确定具有共同运动策略的群体之间的共同特征，如两足动物和四足动物。最后，将以一种新颖的方式探索股骨的特征，这些特征被认为是适应两足动物运动的。系统发育学方法将被用来检验股骨特征从假想的共同(非两足动物)祖先到两足动物后代的变化模式。这些联合分析将有助于更好地了解阿法尔人的股骨近端，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加重要的新数据。除了学术兴趣外，突出埃塞俄比亚化石对研究人类进化的重要性的研究有助于国际上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.