Silurian conulariids from the Lower Visby Beds on Gotland

Abstract: The Silurian conulariid fauna in the Lower Visby Beds (uppermost Llandovery to lowermost Wenlock) on Gotland includes seven species: Ctenoconularia monile Lindström 1884, Ctenoconularia sp. a, Ctenoconularia sp. b, Conularina sp. a, Conularia scalaris Holm 1893, Metaconularia aspersa Lindström 1884 and Metaconularia sp. a. The research on conulariids has so far been based on macroscopic specimens only (except in Brood 1979). One conclusion is that conulariids rarely are preserved as macroscopic specimens in environments affected by bottom currents and bioturbation. It is therefore important to use microscopic specimens to get a complete picture of the fauna. Contra the general opinion, microstructures are treated as the most important diagnostic feature. Morphology of the exoskeleton is described and some new terms adapted to microscopic specimens are introduced.