TURNOVER RATES ASSOCIATED WITH THE MID-CARBONIFEROUS BOUNDARY, BIRD SPRING FORMATION, ARROW CANYON, NEVADA

Extinction and recovery patterns characteristic of Paleozoic marine life changed in the Mid-Carboniferous. Particularly, diversification and rates of evolutionary turnover slowed. This distinctive interval coincided with a change from greenhouse to icehouse climate regimes. Many paleocommunities reorganized at this climate transition causing a second order mass extinction. We examined specimens from the Global Stratigraphic Type Section for the Mid-Carboniferous boundary in the Bird Spring Formation, Arrow Canyon Nevada to reveal how much of the turnover is due to lower origination rate, extirpations (displacement), immigration, and/or actual extinction. Over 200 specimens from the Mississippian and Pennsylvanian have been identified to genus level and taxonomic ranges were determined using the Paleobiology Database. Our results suggest that the regional patterns are much more complex than previously thought.