Diversity changes of the Brachiopods in the Northern Caucasus: a brief overview

Abstract

The diversity of the brachiopods in the Northern Caucasus significantly fluctuated throughout the Paleozoic-Mesozoic. Weak diversifications occurred in the Middle Cambrian, Late Silurian - Early Devonian, and Late Devonian - Early Carboniferous. Since the Late Permian brachiopod assemblages became quite diverse. The maximum number of species was reached in the Rhaetian. The Permian/ Triassic mass extinction and enigmatic Ladinian crisis, on the other hand, led to regional brachiopod demises. In the Jurassic - Early Cretaceous interval the diversity of brachiopods generally decreased. The strongest drops of species numbers occurred in the Toarcian and Berriasian following the Pliensbachian-Toarcian and end-Jurassic global mass extinctions, and in the Kimmeridgian due to the regional salinity crisis. It is evident that some of the regional brachiopod diversifications coincided with the development of rimmed shelves.