DISSERTATION RESEARCH: An integrative assessment of body size and growth patterns in therocephalian synapsids before and after the end-Permian extinction

该奖项支持为期两年的博士研究，以完成对二叠纪末灭绝（约2.52亿年前）前后哺乳动物兽头类祖先的体型和生命史（生长和繁殖）策略的调查。二叠纪末是一个生态系统极度不稳定的时期，地球上90%以上的动物物种灭绝。基于来自南非Karoo盆地的大型哺乳动物类兽脚类化石样本，我们将整合硬组织组织学（骨组织生长）和系统发育比较方法，首次评估兽脚类骨骼中记录的体型缩小和维管生长模式的变化是否受到二叠纪末灭绝的驱动。在此过程中，我们探讨了环境压力和不稳定性的增加如何在宏观进化尺度上影响主要脊椎动物群体的生活史进化。这项研究还将揭示新的生活史策略的起源，比如我们自己的哺乳动物谱系中快速、确定的（哺乳动物一样的）生长。拨款将协助维持一个活跃的组织学设施和分析资源，以支持学生的项目和实验室课程材料，为贫困的未来科学家提供专业发展的机会，并为本所提供新的教学资源。数据将存档在一个免费访问的在线组织学图像数据库和类似的电子数据库（例如，古生物数据库）。此外，与南非机构的合作将加强国际合作，提高一个新兴工业化国家对自然历史、进化和灭绝的认识，并将通过预测生物对未来生态系统扰动的长期反应，帮助为保护现存生物多样性的决策提供信息。

This award supports two years of doctoral research to complete an investigation of body size and life history (growth and reproduction) tactics in the therapsid ancestors of mammals before and after the end-Permian extinction (ca. 252 million years ago), a period of intense ecosystem instability in which more than 90% of animal species on Earth became extinct. Based on a large sample of mammal-like therapsid fossils from the Karoo Basin of South Africa, we will integrate hard-tissue histology (bone tissue growth) and phylogenetic comparative methods to assess for the first time whether body size reductions and changes in vascular growth patterns recorded in the bones of therapsids were driven by the end-Permian extinction. In doing so, we address how increased environmental stress and instability may influence life history evolution in major vertebrate groups on a macroevolutionary scale. This study will also shed light on the origins of novel life history strategies, such as rapid, determinate (mammal-like) growth in our own mammalian lineage.The funding will assist in the maintenance of an active histological facility and analytical resources to support student projects and lab-based course materials, offering opportunities for professional development of underprivileged future scientists and providing new teaching resources to our institution. Data will be archived on a freely-accessible online database of histology images and similar electronic data repositories (e.g., Paleobiology Database). Additionally, work with South African institutions will strengthen international collaborations and raise awareness of natural history, evolution, and extinction within a newly industrialized country, and will help inform decisions on protecting extant biodiversity by forecasting long term biotic responses to future ecosystem perturbations.