Mass extinction and biological responses to Cenozoic environmental change

Modern Antarctic sea floor communities are unusual as many shelf areas are dominated by suspension feeding organisms such as sea lilies, feather stars and brittle stars, with few crushing predators such as crabs, sharks and rays, but it is unclear when this community structure originated. These communities are complex, unique ecosystems that have evolved over millions of years due the balance of many factors such oceanographic changes, the onset of Cenozoic glaciations, sea-water cooling, changes in habitat driven by variations in ice extent and habitat disturbance caused by ice-berg scouring. However, the evolution of these communities is poorly understood. To fully understand the effect of current global warming on these delicate ecosystems in Antarctica we must study the geologic past to establish their responses to changes in environment during their evolutionary history. Studies on the ecology and taxonomic composition of key fossil sites such as Seymour Island and King George Island are helping us to understand how modern Antarctic ecosystems evolved.