Climate change-driven Late Miocene to Pliocene rise and fall of C4 vegetation in Anatolia (Türkiye)

Since the emergence of life on Earth 2.8 billion years ago, plants have been capitalizing on the C₃ photosynthetic pathway. In the world’s grasslands that emerged since the Paleogene, C₄ vegetation expanded considerably between 8 and 3 Ma following climatic changes, which heralded profound terrestrial ecosystem changes. However, sparse reconstructions of C₄ vegetation in the northeastern Mediterranean region prevent a reconstruction of C₃-C₄ vegetation dynamics.

We present the first extensive δ¹³C soil carbonate record for Anatolia (Türkiye) for the last 10 Ma, which we combine with existing records from the Aegean (Greece). Our results show the emergence of C₄ vegetation in Anatolian floodplains by 9.9 Ma, which is similar to regions in NW and E Africa. A transition to C₄ dominance before ca. 7.1 Ma in Anatolia and potentially the Aegean occurs simultaneous with southern Asia during global Late Miocene Cooling in response to decreasing atmospheric pCO₂.However, the patterns of the Anatolian and likely Aegean paleoecosystems are unique due to a rapid and permanent return to C₃ dominance at ca. 4.4 Ma. A return to C₃ dominance is not observed elsewhere in the world and occurs simultaneously with the disappearance of the open environment-adapted large mammal Pikermian chronofauna. We suggest that a regional warm-to-cold season change in rainfall seasonality toward a Mediterranean-style climate triggered the return of C₃ biomass in Anatolia and the vanishing of herbivorous mammal populations of the Old World savannah paleobiome.