“The end-Permian mass extinction led to the disappearance of >81% of marine species and the collapse of marine ecosystems. Despite the progress made in recent years, the severity of the impact of the mass extinction upon some groups still remains unclear. Horseshoe crabs are a typical example among these groups. Here we report a new fossil horseshoe crab, Guangyuanolimulus shangsiensis gen. et sp. nov. from the Permian-Triassic transitional beds in South China, representing the earliest putative fossil record of Limulidae. The occurrence of horseshoe crabs during the Permian-Triassic transition indicates the existence of a trophic web containing at least three levels immediately after the main pulse of the end-Permian mass extinction. Horseshoe crabs might have played an important role as predators in marine communities during the Permian-Triassic transition and the earliest stage of recovery.” Available in Paleo3