Graduation Year

2012

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Geology

Major Professor

Peter J. Harries

Keywords

Climatic modes, Evolution, Extinction rates, Nutrient availability, Origination rates, Planktic foraminifers

Abstract

Deciphering the factors underlying both long-term patterns of diversity and taxonomic turnover rates (i.e., extinction, and origination) has been one of Paleobiology's major foci for the past three decades. The importance of documenting these components is that they will expand our ability to interpret and model the evolutionary processes underlying those trends, highlight the evolutionary impact of historical events, and contribute to the formulation of robust predictions about the future of global diversity in response to the current anthropologically driven environmental changes. Accordingly, the first part of this study examines the possible occurrence of global marine evolutionary environmental controls into a `deep-time' perspective, using a statistical time-series approach between the most recent Phanerozoic global marine generic origination rates with coeval mean global marine geochemical and geological signatures of environmental proxies. After this examination, significant positive correlations were found between changes in origination rates and global mean signatures of 87Sr/86Sr and δ34S, as well as a significant negative correlation between variability in both origination rates and eustatic sea level. They suggest that over secular timescales, nutrient availability, as controlled by continental weathering, phosphorus recycling, and the relative extent of shelf exposure, is an important regulator of genus-level origination in the marine realm, with periods of increased nutrient availability associated with higher origination rates.

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