THE RELATION BETWEEN PLANKTONIC FORAMINIFERAL MORPHOLOGICAL DISPARITY AND NEOGENE OCEANOGRAPHIC EVENTS

Understanding deep-time biodiversity history requires documentation of the relation between patterns of morphological change and patterns of variation in proxies for prospective biotic/abiotic drivers. The unrivaled temporal resolution, morphological complexity and spatial distribution of the planktonic foraminiferal fossil record makes it an attractive target for such investigations in the marine realm. By combining (i.) state-of-the-art quantitative bio-chronostratigraphic and (ii.) character-based morphologic data with (iii.) comprehensive coupled ocean-atmosphere climate model-based summaries of Neogene marine environmental states, a dataset of unprecedented scope and sensitivity has been created. This dataset was then used for the high-resolution macroevolutionary investigation of species-level richness and morphological disparity dynamics over the Neogene interval of earth history. In addition, my approach to this investigation is innovative in terms of its comprehensive geometric assessment of species-specific morphological variation, coupled with use of advanced data dimensionality reduction methods (e.g., UMAP) and a new approach to the quantitative characterization of disparity patterns over time. These features have enabled patterns of disparity variation to be compared with, and modeled as a response to, variations in a variety of Neogene paleooceanographic conditions such as temperature, salinity, productivity and seasonality variations (including estimates of ice volume), at unprecedented levels of temporal, as well as morphological, sensitivity. Results suggest that Neogene planktonic foraminiferal morphologies reflect the operation of multiple physical drivers in time and space. In particular a close link appears to exist between overall taxic richness and morphological disparity across the Neogene. These results, in turn, suggest that some aspects of previous morphological disparity studies in other taxonomic groups may have been subject to bias introduced by ill-suited data-analysis procedures.