Scanning electron microscope (SEM) imaging of fossils allows unlocking ultrastructural information about their skeletal tissues, but sample preparation of biominerals forming their skeletons requires time, patience, and knowledge. SEM and associated analytical methods allow the observation of internal microstructure, shedding light on function, growth and chemistry. Sample preparation is the process by which material is fixed within a medium (e.g. epoxy resin), a transect created and surface defects removed. This step is arguably the most important in any SEM-based analysis, allowing for the acquisition of reliable, high quality data sets. When conducting any SEM-based technique, the presence of a flat surface is needed to collect consistent and reliable data. Surfaces with topography will both induce charging effects but will also compromise the reliability of data acquired. Techniques from material science are continuously adapted to palaeontological applications, in particular with respect to calcareous microfossils. However, similar studies have not been extensively conducted on bioapatite, owing in part to the difficulties faced in sample preparation alongside its susceptibility to electron beam damage. This case study focuses on conodonts, a marine vertebrate group ranging from the late Cambrian to the Late Triassic. They have been chosen as a model due to the abundance of material, complexity of internal tissues and previous work focused on histological features. With these phosphatic microfossils, we attempt to outline the process of sample preparation and provide information on how to avoid and overcome common pitfalls.

化石的扫描电子显微镜 (SEM) 成像可以解锁有关其骨骼组织的超微结构信息，但形成其骨骼的生物矿物的样品制备需要时间、耐心和知识。SEM 和相关的分析方法允许观察内部微观结构，揭示功能、生长和化学。样品制备是将材料固定在介质（例如环氧树脂）中、创建横断面并去除表面缺陷的过程。这一步可以说是任何基于 SEM 的分析中最重要的一步，可以获取可靠、高质量的数据集。在进行任何基于 SEM 的技术时，需要有一个平坦的表面来收集一致和可靠的数据。具有地形的表面既会引起充电效应，也会损害所获取数据的可靠性。来自材料科学的技术不断适应古生物学应用，特别是在钙质微化石方面。然而，类似的研究尚未对生物磷灰石进行广泛的研究，部分原因是样品制备面临的困难以及其对电子束损伤的敏感性。本案例研究的重点是牙形石，这是一种海洋脊椎动物群，范围从晚寒武纪到晚三叠世。由于材料的丰富性、内部组织的复杂性以及以前专注于组织学特征的工作，它们被选为模型。有了这些磷酸盐微化石，