A review of evolutionary trends in carbonate hardground communities

Ancient and modern marine carbonate hardgrounds offer unusual opportunities to study the evolution of communities from the Early Cambrian into the Holocene. Throughout this time the general physical conditions of a hardground community have been similar. The substrate is hard so sessile organisms must either attach to its surface, nestle in cavities, or bore into it for occupation. These organisms are thus preserved in situ. Since space is often the limiting physical resource, organisms must have ways of obtaining and defending it, and these competitive hierarchies are often preserved in the spatial relationships of the species. Scouring and/or burial in sediment usually marks the end of the brief habitation.