The ‘Great Ordovician Biodiversification Event’ represents the rapid diversification of marine organisms during the Middle Ordovician. As the initial stage of the ‘Great Ordovician Biodiversification Event’, the ‘Ordovician Plankton Revolution’ played a crucial role in the increase of biodiversity in the Ordovician. The occurrence, phylogeny, diversity and abundance of caryocaridids, an important and representative group of planktonic arthropods in the Ordovician, may provide important information for studying the ‘Ordovician Plankton Revolution’ and the evolution of pelagic food webs. Based on systematic collection of paleontological data of caryocaridids, combined with phylogenetic methods, we determined the taxonomic position of caryocaridids, discussed the evolutionary path of the group, reconstructed the biological migration process of caryocaridids and its paleoecological and paleogeographical setting. Our results show that caryocaridids were a clade of planktonic arthropods, which are commonly preserved in black shales along with graptolites and pelagic trilobites. The caryocaridids evolved from the late Cambrian phyllocarids. They first appeared in the Tremadocian, rapidly diversified in the Floian to Darriwilian, then declined in the Late Ordovician, and went extinct at the end of the Ordovician. From the late Cambrian to the Early Ordovician, a large number of marine organisms switched to the planktonic mode. The emergence, rise and diversification of planktonic caryocaridids provide new evidence for the diversity of marine plankton, the complexity of the Ordovician pelagic food webs, and the occurrence of the ‘Ordovician Plankton Revolution’.

“大奥陶世生物多样性事件”代表了中奥陶世海洋生物的快速多样化。作为“奥陶纪生物多样性大事件”的初始阶段，“奥陶纪浮游生物革命”对奥陶纪生物多样性的增加起到了至关重要的作用。发生、系统发育奥陶纪浮游节肢动物重要且具有代表性的类核动物的多样性和丰度，可能为研究“奥陶纪浮游生物革命”和中上层食物网的演化提供重要信息。在系统收集类核虫古生物学资料的基础上，结合系统发育学方法，确定了类核虫的分类地位，讨论了该群的进化路径，重构了类核虫的生物迁移过程及其古生态和古地理环境。我们的研究结果表明，caryocarids 是浮游节肢动物的一个分支，通常与笔石和远洋三叶虫一起保存在黑色页岩中. Caryocarids 是由晚寒武世叶螨进化而来的。它们首先出现在 Tremadocian，在 Floian 到 Darriwilian 迅速多样化，然后在晚奥陶世下降，并在奥陶世末灭绝。从晚寒武世到早奥陶世，大量海洋生物转向浮游模式。浮游拟核虫的出现、兴起和多样化为海洋浮游生物的多样性、奥陶纪中上层食物网的复杂性以及“奥陶纪浮游生物革命”的发生提供了新的证据。