An atypical intra-platform environment and biota from the Silurian of Gotland, Sweden

A condensed shale from the middle Silurian of Gotland (Sweden) is herein described with regard to its biotic and environmental significance. The fauna is characterised by an overall low diversity and anomalous abundance patterns, notably a mass-occurrence of scolecodonts. Other elements include abundant chitinozoans, dendroid and graptoloid graptolites, conodonts, eurypterids, and the brachiopod Lingula. An unusually good collection of the rare, minute conodont Aldridgeodus minimus gen. et sp. nov., was recovered and is therefore formally described herein. The conspicuous faunal composition and palaeogeographical position of the shale in the interior area of a carbonate platform is unique for any stratum of Gotland and may represent a rarely preserved environment for the lower Palaeozoic.