USING PALEOENM TO DETERMINE THE EFFECTS OF AVAILABLE ECOLOGICAL NICHE SIZE ON EXTINCTION SUSCEPTIBILITY ACROSS THE K/PG EXTINCTION IN THE MISSISSIPPI EMBAYEMENT

The Cretaceous/Paleogene (K/Pg) boundary extinction is the last of the big five mass extinctions and is often attributed to a large bolide impact off the Yucatan Peninsula. Previous studies have suggested that patterns of survivorship are related to geographic range size as well as proximity to the impact site. Here we investigate changes in abiotic habitat across the K/Pg boundary in the proximal Gulf Coastal Plain (GCP) and compare this to patterns of extinction resistance in Late Cretaceous mollusks. Abiotic habitat in the latest Maastrichtian and early Danian was characterized using sedimentological proxies for environment such as grain size and inferred water depth. These data were then combined with taxon occurrences derived from fieldwork and the Paleobiology Database and analyzed using a Paleo-ecological niche modeling framework (PaleoENM). PaleoENM correlates taxon occurrences with the specific environments in which they occur, thereby providing a prediction of suitable abiotic habitat. Models of suitable habitat were developed in the latest Maastrichtian, then projected into the Danian to determine the availability and size of a taxon’s suitable habitat after the extinction interval. Several surviving and non-surviving genera of mollusks (e.g., Turritella, Eutrephoceras, and Nuculana vs. Discoscaphites, Sphenodiscus, and Baculites) were modeled to test whether survivorship was associated with availability of suitable habitat in the Danian. Preliminary results suggest that surviving taxa show an increase in available abiotic niche space in the Danian compared to the Cretaceous, and taxa that go extinct experience either a reduction or little to no change in available abiotic niche space post-impact. These results suggest that even in a proximal setting likely to be most affected by the K/Pg impact itself, an important component of extinction potential is the size and availability of abiotic niche space after the initial extinction event.