EVALUATION OF MARINE COMMUNITIES BEFORE AND AFTER THE LATE DEVONIAN BIOCRISIS: GREAT BASIN, USA

The End-Devonian marks one of the greatest mass extinction events in geologic history. This extinction affected marine communities globally, as at least three separate events over a geologically short period of time, and resulted in a great biodiversity loss. Despite this, the diversity of marine invertebrates recovered in the early Mississippian, however, marine communities were ecologically very different. In order to begin to understand the nature of this ecological turnover, we sampled six localities in the Great Basin, United States, from intervals before and after the extinction. Packstones and grainstones were targeted from shallow marine environments preserved in the Guilmette Formation (Late Devonian) and the Joana Limestone (Early Carboniferous). Macrofaunal diversity and relative abundance were compiled to broadly compare community structure before and after the extinction interval. Initial observations show that communities in the Guilmette Formation preserved abundant brachiopods as well as reef builders such as the stromatoporoid Amphipora. From the samples collected from the Joana Limestone, crinoids were the dominant group. This ecological restructuring is not obvious looking at taxonomic data alone. Ongoing research will continue to quantify and qualify aspects of marine communities associated with this biocrisis.