The first record of Odontopleura ovata (Trilobita) from Scandinavia: part of a middle Silurian intercontinental shelly benthos mass occurrence

We report here, for the first time, the occurrence of the trilobite Odontopleura (Odontopleura) ovata Emmrich, 1839 from Scandinavia. The specimens came in light during a study of middle Silurian calcareous mudstone formed in offshore settings of the Baltic Basin (Grotlingbo-1 core, south-eastern Gotland). Intrabasinal correlation shows that the taxon had a brief mass occurrence during the latest dubius, parvus-nassa, and dubius-nassa graptolite chrons across the Baltic Shield and East European Platform without inhabiting the carbonate platforms that fringed the basin. The sudden appearance of O. ovata and an abundant brachiopod fauna in the core corresponds in time with a general shelly benthos mass occurrence in the earliest recovery phase of the middle Silurian global conodont and graptolite crisis (the Mulde Event) and correlates with a transgression and geographical expansion of the Baltic Basin.