Large–leaved Annularia species (Equisetopsida) in Pennsylvanian Variscan Euramerica–a Preliminary Review

Abstract

Seven fossil–species can be distinguished within the range of late Carboniferous and early Permian equisetopsid (“horsetail”) foliage formerly assigned to Annularia stellata. The shoots bearing this foliage also produced distinctive strobili often known as Calamostachys tuberculata. These foliage species can be differentiated by leaf and whorl morphology, and each species has a distinct geographical and stratigraphical range. The group first appeared in the intramontane basins of the Variscan Mountains in the late Duckmantian, and then expanded into the lowland paralic coal swamps in the Bolsovian–Asturian. The group continued to flourish in coal swamp refugia during the Stephanian but eventually disappeared during the early Permian.