Silurian Reef-Dwelling Brachiopods and Their Ecologic Implications

Abstract

Abstract Brachiopods were one of the most diverse groups of reef-dwellers during the Paleozoic, and their degree of specialization for reef habitats provides an important way of assessing the ecologic complexity in reef communities. Silurian (Wenlockian) reef brachiopods in Gotland and Wisconsin are compared to level-bottom brachiopods in Gotland, Wisconsin, and the Welsh Borderland. The reef—level-bottom comparisons are made at the level of single bulk samples, as combined groups of samples from single reefs and from single level-bottom communities, and as combined groups of samples from several reefs that occupy the same stratigraphic horizon. Species diversity of reef brachiopods is higher than that of level-bottom brachiopods, but the amount of this difference decreases from the scale of entire reefs to the scale of single samples, where Shannon indices (H′) and rarefaction curves of reef and level-bottom samples commonly overlap. In terms of species richness, maximum reef values reach 44 species (n =...