HOW HAVE MACROPERFORATE PLANKTONIC FORAMINIFER BIOGEOGRAPHIES VARIED THROUGH THE CENOZOIC?

The macroperforate planktonic foraminifera (PF) are the only taxonomic group with a sufficiently complete fossil record to allow for a direct-sampling approach at the species level. Their record has permitted extremely high-resolution studies on paleoceanographic and macroevolutionary dynamics through time, with particular utility within the Cenozoic (<66 Ma) deep-sea record. Detailed work on modern taxa has led to a comprehensive understanding of extant PF morphology and ecology which has allowed the classification of Cenozoic species in to distinct “ecogroups”. This understanding, when applied within the last 66 Ma, has allowed us to study and infer with higher certainty detailed parameters such as temperature, productivity and CO₂ concentrations of the ancient marine realm.

Oceanic changes on geological timescales have also caused concomitant changes in the vertical and biogeographical distributions of PF. Recent studies have demonstrated that PF exhibit distinct paleolatitudinal restructuring during key intervals such as the transition from the Eocene to Oligocene when permanent continent-scale Antarctic ice sheets ice sheets, after which the clade develop a clear latitudinal diversity gradient (LDG) reminiscent to that of the modern day.

This project further develops our understanding of ancient PF global distribution patterns and elucidates the primary drivers of biogeography within macroperforate PF “ecogroups” during the Cenozoic. We demonstrate that PF “ecogroups” exhibit consistent, measurable ecological and biogeographical responses to discrete or harmonious biotic and abiotic stimuli such as interspecific interactions and global climate parameters. Our work utilises extinct PF “ecogroup” paleolatitudinal datasets derived from the NEPTUNE database spanning the entire Cenozoic, collated into <1 Ma time bins. Through this methodology, we were able to track biogeographical ranges through time, and investigate their relationship with our current understanding of marine biological interactions and Cenozoic climate development.