Tracing the origin of the planktic graptolites (Hemichordata, Pterobranchia) through the Furongian Gap (Upper Cambrian)

古生代(晚寒武世)是了解浮游笔石(笔石亚纲：翼手亚目)起源和早期演化的关键时期，也是笔石在生物地层学中地质应用的起点，早在寒武纪底部笔石的起源之后。不幸的是，这个需要填补的化石产量低的空隙掩盖了我们对浮游笔石起源和早期演化的理解。浮游性笔石化石似乎突然起源于奥陶纪的底部，人们对其在这段时间内的早期进化变化知之甚少。中国等人的芙蓉纪果乐拉格斯特特发现了多种多样的海底笔石动物群，结合绿点(加拿大纽芬兰)寒武纪/奥陶纪GSSP剖面和大洋茶剖面(中国)对早期浮游笔石动物群的研究，将有助于揭示笔石的演化及其对早古生代海洋环境的探索。笔石中浮游生物营养的起源及其筒状结构的相关修改导致了世界上大片海洋中最早的大型浮游生物的繁殖，在泥盆纪早期，网生生物和浮游生物食性超过了这些生物。

The Furongian (late Cambrian) time interval is the key interval to understand the origin and early evolution of planktic graptoloids (Graptolithina: Pterobranchia) and the starting point for the geological application of graptolites in biostratigraphy, long after the origination of the graptolites in the basal Cambrian. Unfortunately, the ‚Furongian Gap‘, an interval of low fossil yield that needs to be filled, masks our understanding of the origin and early evolution of planktic graptolites. It appears that planktic graptoloids suddenly originated at the base of the Ordovician and little is known about their early evolutionary changes during this time interval. The Furongian Guole lagerstätte of S. China yield a diverse benthic graptolite fauna, which, together with the investigation of early planktic graptolite faunas from the Cambrian/Ordovician GSSP section at Green Point (Newfoundland, Canada) and the Dayangcha section (N. China) will shed light on this chapter in the evolution of the graptolites and their exploration of the oceanic environment in the early Paleozoic. The origin of planktotrophy in the graptolites and the associated modifications in their tubarium formation led to the earliest macro-plankton populating the expanses of the world’s oceans, before nektic organisms and plankton feeders outcompeted these organisms in the early Devonian.