NICHE DYNAMICS OF MARINE MOLLUSKS ACROSS THE END-CRETACEOUS MASS EXTINCTION IN THE GULF COASTAL PLAIN REGION OF THE US

The Cretaceous-Paleogene boundary (KPB) represents one of the most severe biotic catastrophes in the geological record. Despite years of research regarding the KPB, abiotic niche dynamics of molluscan taxa across this interval have not been well studied. Furthermore, niche stability (maintenance of niche traits within a species over evolutionary time), is often assumed in modern ecological studies, but has not been vigorously tested in the fossil record where physical evidence for niche change on evolutionary timescales can be found. To fill in these knowledge gaps, we applied ecological niche modeling (ENM) and associated statistical techniques to explore how species’ abiotic niches responded to environmental change during the Cretaceous-Paleogene transition We tested two hypotheses: 1. Widespread area and distribution of available suitable habitat contributed to survivorship across the KPB; 2. Species’ abiotic niches remained stable regardless of the sudden environmental changes associated with the KPB. To test our hypotheses in an ENM framework, we obtained molluscan fossil occurrence and environmental data from shallow marine deposits of the U.S. Gulf Coastal Plain. We constructed environmental layers using sedimentological and geochemical proxies in conjunction with recently updated global climate models. Preliminary results from an earlier pilot dataset suggest a rejection of the former hypothesis, with the latter test in process. Analyses that apply ENM to the fossil record (PaleoENM) are important as they provide a litmus test for how modern organisms may respond to rapid environmental change both now and in the future.