East African uplift as a catalyst for Middle Miocene faunal transitions.

Abstract

The East African uplift during the Miocene played a crucial role in reshaping regional climates, ecosystems, and faunal communities, contributing to a shift from forested landscapes to widespread grasslands. Here, we use the high-resolution Earth System Model EC-Earth3, coupled with a dynamic vegetation model, to simulate climate and vegetation responses to East African uplift across three key Miocene intervals (25, 20, and 15 Ma) under varying atmospheric CO₂ levels. Our results show that tectonic uplift, combined with declining CO₂ during the Middle Miocene Climate Transition, substantially reduced forest cover and promoted grassland expansion across East and Central Africa. These environmental transitions likely facilitated faunal dispersals and ecological turnover, including among large mammals and early crown hominoids. By integrating geodynamic reconstructions, paleoclimate modeling, and fossil data, this study provides insight into how large-scale Earth system processes shaped Miocene biodiversity and altered the environmental context for mammalian evolution in Africa.