Diversity dynamics of Early and Middle Jurassic brachiopods in the Getic and Danubian tectonic units of eastern Serbia: Regional versus global patterns

Abstract

Quantitative assessment of regional diversity patterns reveals trajectories of faunal development on the basin scale and helps to understand its dependence on palaeoenvironmental changes, global-scale biotic evolution, and major events in the history of the Earth. A total of 86 species, 50 genera, 18 families, and 9 superfamilies of Early and Middle Jurassic brachiopods are established in the Getic and Danubian tectonic units of eastern Serbia. Compilation of their stratigraphic ranges allows analysis of their total diversity, number of appearances and disappearances, and turnovers. In both units, brachiopods radiated rapidly in the Early Pliensbachian. Then, their diversity declined, and these fossils disappeared. A new radiation took place in the Late Bajocian, and brachiopods remained diverse until the end of the Bathonian. They disappeared before the Callovian in the Getic Unit and in the Early Callovian in the Danubian Unit. The Early Pliensbachian radiation was significantly stronger than the Late Bajocian at the level of species; the strength of these radiations was more or less comparable at higher taxonomic levels. The strength of turnovers among brachiopods differed through geological time. The composition of the Middle Jurassic brachiopod assemblages was more or less stable. Regional shoreline shifts, basin depth changes, palaeobiogeographical changes, and plate tectonic re-organizations were possible controls on regional patterns of brachiopod diversity dynamics. However, the latter also reflects some diversity patterns documented globally and in some other regions (the Bakony Mountains, the Swiss Jura Mountains, and the Northern Caucasus).