Article: Carboniferous orthosterni and their relationship to living scorpions

Five species of Upper Carboniferous orthostern scorpions are described from Britain and North America. Two are established taxa, and three are new: Palaeopisthacanthus vogelandurdeni sp. nov., Cryptoscorpius americanus gen. et sp. nov., and Corniops mapesii gen. et sp. nov. An additional species, Gymnoscorpius mutillidigitus gen. et sp. nov., is referred to the suborder Neoscorpionina, but is too incompletely known for its systematic position to be determined more accurately. The descriptions are based on fragmentary material from dispersed arthropod cuticle assemblages. These have yielded sufficient anatomical detail to assess the relationship between fossil and Recent orthostern scorpions for the first time. A cladogram is presented, demonstrating that Carboniferous orthosterns comprise the stem group from which all Recent scorpions (the crown group) were derived. The recognition of important character state transition series in the Orthosterni, and their polarities, will facilitate more accurate assessment of the relationships between modern scorpion genera.