Ostracods are the most abundantly preserved arthropod group in the fossil record, but they are almost entirely represented only by their calcitic carapaces. In over two hundred years of fossil ostracod research, only about 33 occurrences of fossil ostracods that include preserved appendages, or soft parts, have been reported. These range from the Ordovician through to the Holocene, and are from a wide range of paleoenvironments, including the seas, brackish inlets, lakes, caves, and the edges of ancient forests. Preservation includes silica, phosphate, goethite, pyrite or calcite mineralization replacing or coating soft parts, or direct preservation of the chitinous body and appendages, such as with amber entombment and mummification. Although rare, they have provided information on the morphology of some of the earliest ostracods, given clues about phylogenetic relationships of extinct groups, and demonstrated remarkably long periods of evolutionary stasis. Preserved sexual organs, eggs, brooded juveniles and even spermatozoa have given valuable insights into the reproduction of the group. Technological advances, such as scanning electron microscopy and more recently micro- and nanotomography, have dramatically expanded our capabilities to study these specimens, even down to the sub-cellular level. This review presents these occurrences in a historical context, from the first to the most recently reported, and highlights how these discoveries have contributed to our understanding of ostracod evolution.

介形类动物是化石记录中保存最丰富的节肢动物群，但它们几乎完全只由它们的钙质甲壳代表。在 200 多年的介形虫化石研究中，仅报告了大约 33 次化石介形虫，包括保存完好的附肢或柔软部分。这些范围从奥陶纪到全新世，来自广泛的古环境，包括海洋、咸水入口、湖泊、洞穴和古代森林的边缘。保存包括二氧化硅、磷酸盐、针铁矿、黄铁矿或方解石矿化替代或覆盖软部件，或直接保存几丁质体和附属物，例如琥珀埋葬和木乃伊。虽然很少见，但他们提供了一些最早的介形虫形态的信息，给出了关于灭绝群体的系统发育关系的线索，并展示了非常长的进化停滞期。保存下来的性器官、卵子、育雏甚至精子都为该群体的繁殖提供了宝贵的见解。技术进步，例如扫描电子显微镜和最近的显微和纳米断层扫描，极大地扩展了我们研究这些标本的能力，甚至可以深入到亚细胞水平。这篇综述在历史背景下介绍了这些事件，从第一次到最近的报道，并强调了这些发现如何有助于我们对介形虫进化的理解。孵卵的幼体甚至精子都为该群体的繁殖提供了宝贵的见解。技术进步，例如扫描电子显微镜和最近的显微和纳米断层扫描，极大地扩展了我们研究这些标本的能力，甚至可以深入到亚细胞水平。这篇综述在历史背景下介绍了这些事件，从第一次到最近的报道，并强调了这些发现如何有助于我们对介形虫进化的理解。孵卵的幼体甚至精子都为该群体的繁殖提供了宝贵的见解。技术进步，例如扫描电子显微镜和最近的显微和纳米断层扫描，极大地扩展了我们研究这些标本的能力，甚至可以深入到亚细胞水平。这篇综述在历史背景下介绍了这些事件，从第一次到最近的报道，并强调了这些发现如何有助于我们对介形虫进化的理解。