DISSERTATION RESEARCH: Temporal Patterns in Non-mammalian Synapsid Morphospace

非哺乳类合孔类动物代表了二叠纪和三叠纪早期（3亿至2.45亿年前）陆地脊椎动物（四足动物）的主要群体。非哺乳动物的合胞类有着非常丰富的、时间上清晰的化石记录。本计画将利用几何形态分析来研究非哺乳类类联会动物的演化模式。几何形态测量学比较样本上共有特征或标志的位置（例如头骨之间的缝合边界），以总结个体之间的形态（形状）变化。研究人员将使用全球非哺乳类突触体标本数据集，解决与该群体辐射相关的进化速率和形态趋势问题。非哺乳类突触体占主导地位的时期被二叠纪-三叠纪灭绝打断，这是地球历史上最大的大规模灭绝，其中95%的物种估计已经消失。研究人员将在灭绝前后检查突触动物群，以确定某些形态是否优先丢失，而其他形态则幸存下来。这些数据可用于识别其他分类群中潜在的易于灭绝的形态。早期的联会动物也很重要，因为它们代表了哺乳动物的祖先。研究突触体历史过程中的形状变化将为哺乳动物起源的进化动力学提供重要信息。

Non-mammalian synapsids represent the dominant group of terrestrial backboned animals (tetrapods) during the Permian and Early Triassic Periods, 300-245 million years ago. Non-mammalian synapsids have a very rich, temporally well-resolved fossil record by tetrapod standards. This project will use geometric morphometric analysis to study evolutionary patterns in the non-mammalian synapsids. Geometric morphometrics compare the positions of shared features, or landmarks, on specimens (e.g. suture boundaries between bones of the skull) to summarize morphological (shape) variation among individuals. Using a global dataset of non-mammalian synapsid specimens, the researchers will address questions of evolutionary rates and morphological trends associated with the radiation of the group.The period of non-mammalian synapsid dominance was punctuated by the Permo-Triassic extinction, the greatest mass extinction in earth history, in which 95% of all species are estimated to have been lost. The researchers will examine synapsid faunas before and after the extinction to determine whether certain morphologies were preferentially lost, while others survived. These data can be used to identify potentially extinction-prone morphologies in other taxa. Early synapsids are also important because they represent the ancestors of mammals. Studying shape change over the course of synapsid history will provide important information on the evolutionary dynamics underlying mammal origins.