Global and Regional Chitinozoan Biodiversity Dynamics in the Ordovician: Relationships to Sea-Level, Carbon Cycling and Tectonics

Fossil species provide extensive information about the past history of life on Earth. This thesis focuses on the global and regional biodiversity dynamics of the extinct fossil group Chitinozoa, and analyzes the impact and influences of sea-level, global carbon cycling and tectonics on their biodiversity. Biodiversity curves were generated from three different paleo-continents, Laurentia, Baltica, and Gondwana using the automated graphic correlation computer program CONOP9. Traditional methods of biodiversity analysis count fossil taxa in individual intervals of geologic time. The results of these methods are highly dependent upon interval length and the relationship of taxon range to interval boundaries. CONOP9 utilizes an interval free approach to biodiversity analysis. Chitinozoan stratigraphic range data from fossil species collected on several ancient continents (Baltica, Laurentia, and Gondwana) were also combined and analyzed to compare the regional and global biodiversity plots. These biodiversity patterns were then compared to existing sea-level and carbon isotope excursion curves to examine the relationship between environmental change and Chitinozoan biodiversity. The three major carbon isotope excursions of the Ordovician, the MDICE, GICE, and HICE all occur during periods of reduced global chitinozoans biodiversity. Additionally, sea level to some extent appears to be related to chitinozoan biodiversity with reduced biodiversity during periods of sea level decrease and increasing biodiversity during periods of higher sea level