Tomagnostussibiricus Pokrovskaya & Egorova, 1972 (Trilobita) from the Middle Cambrian Exsulans Limestone of Scania, Sweden

摘要

Species assigned to the Middle Cambrian agnostid genus Tomagnostus are briefly reviewed and a large number of Tomagnostus sibiricus found in Scania, Sweden, are described. The material derives from the Triplagnostus gibbus Zone in the Exsulans Limestone. Several morphological features support an assignment of the species to Tomagnostus: occasional scrobiculation of the cephalon, half of the cephala have an incipient frontal sulcus, pygidia have well-developed F2 furrows, well-defined transverse depression on posteroaxis and occasionally minute marginal spines or swellings. One pygidium of the biostratigraphically important Pentagnostus praecurrens and one pygidium of the rare Onymagnostus seminula are also described from the Exsulans Limestone of Brantevik, Scania. The new findings expand the stratigraphic ranges of these species in Scandinavia.