Doctoral Dissertation Research: Identifying dental morphological variation among Pliocene hominins

这个博士论文项目分析了人类牙齿特征的大小和形状的变化，这些牙齿特征可以追溯到420万到300万年前。在过去的几十年里，这么古老的牙齿化石的可用性大大增加，然而这些发现中的许多都是孤立的牙齿，仍然不属于任何物种或属。为了解决这个问题，博士生使用了一种新的方法，可以改进古人类牙齿的分类鉴定，并进一步了解这些古人类物种之间的牙齿和形态界限。未归属于某一物种的古人类牙齿化石所获得的信息不能完全纳入古人类学分析，因而仍未得到充分利用。除了培训研究生外，该项目还包括培训本科生，并计划通过外展活动与公众分享结果，最终的3D扫描结果将在公共存储库中提供。该项目收集了420万至300万年前所有已知上新世古人类物种牙齿的公制、非公制和二维地标数据。目的是评估来自该时期遗址的许多分类上未归属的孤立牙齿的亲和力。在每个比较物种的牙齿的大样本大小允许有意义的观察，以确定离散的牙齿特征或一组特征为每个分类单元。一旦鉴定，这些可以用于新发现的分离牙齿的分类鉴定。考虑到最近关于上新世古人类多样性和南猿-阿法南猿谱系物种形成模式的假设，对所得结果进行了解释。此外，该项目产生的牙冠咬合图像、化石模型的三维扫描以及牙齿度量、非度量和地标测量对未来的研究具有重要意义。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This doctoral dissertation project analyzes the variation in size and shape of dental traits among hominins from fossil teeth that are dated to 4.2-3.0 million years ago. The availability of fossil teeth this old has increased significantly in the last decades, yet many of these findings are of isolated teeth that remain unattributed to any species or genus. To address this issue, the doctoral student uses a new approach that allows for improved taxonomic identification of ancient hominin teeth and furthers the understanding of dental and morphological boundaries between these hominin species. Information derived from hominin fossil teeth that are not assigned to a species cannot be fully integrated into paleo-anthropological analyses and remain underutilized. In addition to training a graduate student the project includes the training of undergraduate students, along with plans to share results with the public through outreach activities, and the resulting 3D scans will be made available in public repositories. This project collects metric, non-metric, and two-dimensional landmark data from the teeth of all known Pliocene hominin species dated to 4.2 to 3.0 million years ago. The goal is to assess the affinity of numerous taxonomically unattributed isolated teeth that come from sites dated to that period. The large sample size of teeth in each of the comparative species allows meaningful observations in terms of identifying discrete dental traits or set of traits for each taxon. Once identified, these can be used in the taxonomic identification of newly discovered isolated teeth. Results obtained are interpreted considering recent hypotheses regarding Pliocene hominin diversity and the mode of speciation in the Australopithecus anamensis-Australopithecus afarensis lineage. Furthermore, the occlusal images of tooth crowns, three-dimensional scans of fossil casts, and dental metric, non-metric, and landmark measurements generated by this project are significant for future research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.