Phanerozoic Evolution Trends within Benthic Foraminifera

• Main Author: Faulkner, Katherine
• Other Authors: Martindale, Rowan
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: Biology; geology; foraminifera; paleoclimate; proxy; Ocean acidification
• Online Access: https://hdl.handle.net/2152/118526; https://doi.org/10.26153/tsw/45405

Foraminifera are marine protists that evolved and diversified throughout the Phanerozoic Eon. These protists construct their shells (called “tests”) from their surrounding environment. Foraminifera tests fossilize in great abundance and are sensitive to ocean chemistry and climate. In this study, the relative proportions of calcareous and agglutinated foraminifera are used to understand changes in ocean chemistry over 541 million years. With this data, I aim to answer the following question: How have benthic foraminifera responded to short- and long-term changes in global ocean chemistry? This was accomplished by aggregating diversity-level information from Foraminifera Genera and their Classification, published by Alfred R. Loeblich and Helen Tappan, the most recent and commonly-used reference literature for foraminiferal genera. I built a dataset by recording the accepted names, wall type, and time interval of 3,114 taxa (2,442 genera). Using the genera, binned by Epoch, I tracked wall-type diversity, compared the ratios of calcareous versus agglutinated foraminifera, and contextualized foraminiferal responses to geologically-significant events. I found a notable decrease in relative abundance of calcareous foraminifera during the mid-Carboniferous warming and the end-Permian mass extinction. These changes in the Paleozoic imply that benthic calcifiers organisms were more sensitive to changing ocean acidification and temperatures. However, despite documented climatic fluctuations throughout the Cenozoic, calcareous foraminifera remain stable around 80% diversity from the Eocene through the Pleistocene. This implies benthic calcifiers were more resilient to changes in the Cenozoic, which may be due to pelagic calcifiers stabilizing the carbonate saturation. Comprehensive datasets such as this are essential for research about faunal diversity and paleoclimate records, ocean chemistry, and conservation because it provides insight into how benthic marine organisms respond to and interact with their marine ...