Early Devonian stylonurine eurypterids from northern Gondwana: Late Lochkovian to early Pragian records from South China

This paper describes a new stylonurine eurypterid: Qujingopterus spineus gen. et sp. nov., from the Early Devonian (late Lochkovian to early Pragian) Xitun formation of Yunnan Province, South China. This discovery represents one of the earliest stylonurine records from Gondwana and further supports the global distribution of stylonurines. Considering the probable region of origin of the clade and and their lack of anatomical structures adapted for swimming, we propose that stylonurines migrated to Gondwana as the Rheic Ocean dwindled while Gondwana rapidly approached Laurussia. An additional specimen from this locality is described, and can be assigned to the eurypterine family Pterygotidae. Based on the environmental analysis, it can be inferred that the eurypterids from South China underwent adaptations to cope with decreasing salinity levels. This discovery provides valuable insights into the timing and mechanisms underlying eurypterid invasion into freshwater ecosystems.