Showcase of Undergraduate Research and Creative Endeavors (SOURCE)

Ecological Turnover of Marine Ecosystems as a Result of The Late Devonian Mass Extinction: Communities Shifting Through Time

The end-Devonian was a time of major diversity loss due to 3 major pulses of extinction, which has cemented it as one of the “big 5” mass extinctions. Marine communities were greatly affected during this time, especially shallow marine organisms. These bionomic changes led to one of the most dramatic ecological shifts in marine communities witnessed throughout geological history. To better understand these shifts through time, samples were collected from both before and after the extinction. Each sample was associated with a specific time interval and location, including the Guilmette Formation (Late Devonian) and the Joana Formation (Early Mississippian). Taxonomic composition of communities before and after the extinction event are identified through thin sections. The grain solid method was used to test for shifts in marine assemblages by identifying skeletal fragments based on mineral composition and texture. Preliminary data indicates that these marine communities underwent an ecological restructuring from brachiopod dominated to echinoderm dominated communities, from the Late Devonian to Early Mississippian. Applying this information to communities in the present day will provide a better understanding of how communities shift in dominance over time, and will also contribute to a larger conversation about what may cause shifts in community structure as a result of mass extinctions.