INVESTIGATING MOLLUSCAN SPECIES RESPONSES TO ENVIRONMENTAL CHANGE IN THE LATE CRETACEOUS USING PALEOENM

During the early Late Cretaceous the Western Interior Seaway experienced a global oceanic anoxic event (OAE2, or the Bonarelli Event) across the Cenomanian-Turonian (C-T) boundary (~94 Ma). The major environmental and biological disturbances initiated by this event resulted in significant biotic turnover, suggested by some to be near mass extinction levels. Here we utilize a modern ecological modeling technique (ENM) to test whether changes in species’ abundance across the C-T boundary were related to changes in predicted suitable habitat area and abiotic niche dimensions. More recently this multivariate statistical modeling technique has been applied to the fossil record (PaleoENM) to test questions about long-term niche dynamics and species-environment interactions in deep time.

Preliminary results suggest that species abundance is positively correlated with available suitable habitat area: species with increased abundance across the C-T boundary are associated with an increase and/or greater continuity of suitable habitat area; species with decreased abundance across the boundary are associated with decreased suitable habitat area and increased habitat patchiness; and species with similar abundance show little change in suitable habitat area. These latter species also show consistent occupation of abiotic niche space, suggesting niche stability and habitat tracking across the C-T environmental perturbation. Notably, these results are consistent irrespective of higher taxonomic groups, which suggests species-specific responses to major environmental perturbations. This research supports the importance of biogeography in understanding species longevity and the maintenance of biodiversity, which may positively inform conservation efforts and predictions of modern extinction dynamics.