CELL-SEARCHING: DID HABITAT OPENNESS PARALLEL GRASS DOMINANCE IN THE CENOZOIC ASSEMBLY OF GREAT PLAINS GRASSLANDS?
To address these outstanding questions, we use a recent method for estimating ancient canopy cover (reconstructed Leaf Area Index; rLAI) from the morphology of epidermal phytoliths. These phytoliths form when silica fills epidermal cells that change in shape and size with changing light conditions. We measured epidermal phytoliths from nine late Eocene–early Miocene sites. Reconstructions suggest that habitats remained closed through much of this period, with canopy cover comparable to modern closed forests at all sampled sites. Although preliminary, these results are consistent with the persistence of a closed canopy in the region even after open habitat grasses became ecologically dominant. Currently, we are working to increase the number of phytoliths sampled at each site, and to expand the geographic and temporal coverage our dataset by incorporating additional fossil localities. Ultimately, understanding how habitat structure changed during the lead up to, and initial expansion of grasslands in the Great Plains Region will contribute to a better understanding of the drivers and consequences of this major transition.