Origin of brachiopod-bryozoan assemblages in an Upper Carboniferous limestone: importance of physical and ecological controls

Skeletal accumulations in the Upper Carboniferous Bird Spring Formation of southern Nevada have yielded new information regarding ecological succession in the fossil record and the development of shell concentrations. Through hydraulic baffling processes, a community dominated by cndobyssate bivalves and strophomcnid brachiopods was locally supplanted by a community composed primarily of bryozoans, compositid brachiopods, and various epizoans. The general trophic and diversity changes resemble those expected during 'short-term ecological succession' but are due for the most part to the sedimentological and hydraulic regime. In view of this evidence, previous paleontologic examples of 'autogenic' succession arc re-interpreted as having been primarily controlled by the physical environment. Upper Carboniferous, Brachiopoda, Bryozoa, paleoecology, ecological succession, epifauna.