Updating the timeline of faunal endemism in Balkanatolia, the biogeographic province connecting Europe, Asia and Africa

Abstract

Balkanatolia is a Paleogene insular biogeographic province, spanning from southeastern Europe to the Caucasus. It is located at the crossroads of Asia, Europe, and Africa, from which it remained isolated until the late Eocene, fostering endemism, particularly among mammals. However, the timing of emergence of Balkanatolia as an independent biogeographic province remain debated due to the paucity of the fossil record and loose age constraints. Here, we refine this timing by combining magnetostratigraphy, biostratigraphy, geochronology and sedimentology to date three fossil sites of central Anatolia (Çamili Mezra, Ciçekdagi, and Bultu-Zile). These sites have yielded remains of embrithopods, a clade of large herbivorous afrotherian mammals that originated in Africa and dispersed across the Neotethys to reach Balkanatolia where they diversified. The Çamili Mezra locality yield an age spanning from 46.2 Ma to 43.5 Ma, likely around ∼ 45 Ma based on accumulation rates, the Ciçekdagi locality is dated to the very base of Chron C20r (ca. 46.2 Ma) and the Bultu-Zile locality yield overlapping 46.5 ± 1.0 Ma and 45.1 ± 0.9 Ma ages. Overall, these fossil localities are coherently dated to the early Lutetian and represent the oldest unequivocally embrithopod-bearing sites of the northern Neotethysian shores. They provide an early Lutetian minimum age for Balkanatolian endemism, its emergence as an independent biogeographic province and for the overwater dispersal of embrithopods out of Africa.