THE MORPHOLOGICAL PLASTICITY OF OSTRACODS IN RESPONSE TO THE CARIBBEAN EXTINCTION EVENT

The formation of the Isthmus of Panama is regarded as one of the greatest geological events of the Cenozoic, connecting both the North and South American continents and driving the closure of the Central American Seaway. The closure of this seaway initiated a massive collapse in productivity in the Caribbean that led to a major regional extinction of marine taxa, which we call the Caribbean Extinction Event. To date, studies have focused on the macroevolutionary and faunal response of tropical marine biota to the Caribbean Extinction Event, but the morphological implications of such an extinction event have yet to be carried out in detail. Ostracods are microscopic bivalved crustaceans with known sensitivity to environmental perturbations. The excellent fossil preservation of the entire carapace on their body, in addition to important morphological features like eye tubercles, makes ostracods an ideal organism to investigate morphological changes related to the extinction event. This project aims to assess the morphological plasticity of many ostracod taxa via the body and eye size in response to the regional productivity decline and closure of the Central American Seaway. The project will make use of the Keyence Automated Microscope and Scanning Electron Microscope to quantify the maximum height, length, and volume of the ostracod carapace and eye tubercules. Results on ostracod body size trends at different stages of the formation of the Isthmus of Panama will be presented at the conference.