A PHYTOLITH-BASED RECONSTRUCTION OF GABI ENVIRONMENTS IN CENTRAL MEXICO

The dispersal events of the Great American Biotic Interchange (GABI) are traditionally thought to begin approximately 3 mya during the Pliocene, pulses of earlier dispersals are recognized as early as the mid-Miocene. Vegetation for this extent of time in crucial regions to the dispersal route like Central Mexico has been under-studied, leaving large gaps in our understanding of the setting and requirements of these periods of movement. We present preliminary results of a phytolith-based reconstruction of vegetation from the Neogene basins of Central Mexico to help establish environmental context for dispersal of fauna during the Miocene and Pliocene and to add to our understanding of the timing and distribution of the evolution of early C4 grasslands in Mexico. Our findings indicate complex interactions between grassland and forest environments across the late Miocene and Pliocene, with a substantial decrease in palms across this timeframe, and an abundance of C4 grasses at the end of the Miocene and beginning of the Pliocene, aligning with global patterns of C4 grassland expansion.