Deep-time perspectives on climatic and oceanographic change are critical for understanding the long-term controls on environmental processes. This is particularly the case for the 'tipping points' that lead to episodes of climatic extremes, events that are often associated with episodes of profound biodiversity change. The spatial and temporal distribution of planktic organisms has proven to be critical to the reconstruction of climatic and oceanographic conditions during the Mesozoic and Cenozoic. The oldest geological period for which there is a diverse and abundant record of zooplankton is the Ordovician, and that record is provided by graptolites. PIs objectives are to analyze the changing biogeographic distribution patterns in graptolites from the mid-Ordovician into the lower Silurian using newly developing global databases, ecological modeling, and paleo-GIS techniques. Graptolite spatial distribution patterns should help understand the relationship between ancient ocean structure, climate, and zooplankton biogeography. Strong parallels have recently been drawn between the glacial-interglacial cycles of the Late Ordovician-Early Silurian and those of the late Cenozoic. Therefore, understanding the biogeographic and biodiversity changes associated with these climatic cycles will provide insights relevant to our understanding of biotic response to recent and modern climate change. Although this study will focus on the Ordovician and Early Silurian biosphere and its interconnections, the questions PIs propose to pursue - how range area and spatial patterning of faunas affect or respond to changing environmental history and species evolutionary dynamics - are fundamental questions that biologists and paleobiologists are pursuing across our traditional disciplinary boundaries of taxon, age, and conceptual approach.
