The Systematic and Phylogenetic Significance of the Hominin Temporal Bone: A Landmark-Based Approach

本研究解决了一系列未解决的问题，在原始人类进化使用新的和快速发展的方法来定量分析骨骼形态在几何形态计量学领域。研究人员建议对早期人类颅骨颞骨进行比较解剖学分析，以获得用于化石标本物种归属的关键形态学特征鉴定的新视角，更广泛地说，在进化背景下研究灵长类动物骨骼变异的方法方法。这两个领域都是困难的，但却是关键的研究领域，沿着回答有关早期人类进化的具体问题的道路。他们之所以选择研究早期人类头盖骨的颞骨，是因为：1)关于早期人类进化的几个争论集中在颞骨上，颞骨在解剖学上是复杂的，并且在不同的进化谱系中分化良好；2)以前的分析主要集中在颞骨形态的定性比较上，这在解决悬而未决的争论方面没有取得进展；3)颞骨在古人类化石记录中有很好的代表性；他们的方法非常适合于研究碎片化石，这些化石构成了整个颞骨样本的重要组成部分。通过研究人类颞骨，他们解决了以下这些尚未解决的问题：1)有文献记载的最早的人属代表是什么？2)在传统认识的物种（如南方古猿阿法种、非洲古猿等）中，是否存在分类学上的异质性？3)如何解释“健壮”的南方古猿物种与人属之间独特的亲缘关系（同质性vs突触性）？该方法采用颞骨上的三维地标来量化形态学特征的表达，迄今为止，形态学特征仅在定性和/或单变量背景下进行了检查。具体来说，他们使用“相对弯曲分析”来量化整体形状变化，使用“薄板样条分析”来描述和图形化描绘分类群或标本之间的差异。目标是识别颞骨形态的新方面，以区分古人类分类群。

This study addresses a series of unresolved issues in hominid evolution using new and rapidly developing approaches to the quantitative analysis of bone form in the field of geometric morphometrics. The researchers propose to analyze the comparative anatomy of the temporal bone of the early hominid cranium in order to arrive at fresh perspectives on the identification of key morphological characters used to attribute of fossil specimens to species, and, more generally, on methodological approaches to the study of primate skeletal variation in an evolutionary context. Both are difficult, but critical areas of research, along the road to answering specific questions concerning early hominid evolution.They chose to study the temporal bone of the early hominid cranium because: 1) several debates concerning early hominid evolution center on the temporal bone, which is anatomically complex and well differentiated in the various evolutionary lineages; 2) previous analyses have focused on qualitative comparisons of temporal bone form, which have not led to progress in resolving outstanding debates; 3) the temporal bone is well represented in the hominid fossil record; 4) their methods are well suited to the study of fragmentary fossils, which comprise a significant component of the total temporal bone sample.Studying the hominid temporal bone, they address such unresolved questions as: 1) What are the earliest documented representatives of the genus Homo? 2) How much, if any, taxonomic heterogeneity exists within conventionally recognized species such as Australopithecus afarensis, A. africanus, and others? 3) How should the morphological signs of unique affinity between "robust" Australopithecus species and Homo (homoplasy vs. synapomorphy) be interpreted? The approach employs three-dimensional landmarks on the temporal bone to quantify the expression of morphological features that have thus far been examined only qualitatively and/or in a univariate context. Specifically, they use "relative warp analysis" to quantify overall shape variation and "thin-plate spline analysis" to describe and graphically portray difference between taxa or specimens. The goal is the identification of novel aspects of temporal bone morphology to distinguish hominid taxa.