About 34 million years ago, native fauna disappeared from Western Europe, as mammals from Asia took over. The extinction, known as the Grande Coupure or "great break," might as well have been called the great puzzle. For decades, researchers have been unable to explain how animals from eastern Asia reached Western Europe, as the regions were then separated by sea, per the Big Think. Now, we may have the answer, due in part to some "very weird fossil animals" unearthed in the Balkan region, paleogeologist Alexis Licht, lead author of a new study, tells Business Insider. They show that six million years before the extinction, a forgotten island continent shifted to connect Europe and Asia, and the consequences were enormous.
Fifty million years ago, the land making up the Balkans and much of Turkey formed an island home to unique species not seen anywhere else, according to researchers, who examined distinctive fossils from the region. But around 40 million years ago, tectonic shifts combined with a 230-foot drop in sea levels to turn Balkanatolia—named in honor of the Balkans and Turkey's Anatolia peninsula—into a land bridge or series of land bridges connecting Asia and Western Europe, reports NBC News. The result was an invasion of Asian rodents and hoofed mammals, including distant ancestors of modern-day horses, which wiped out the fauna of Western Europe and Balkanatolia, as the fossil record shows.
Adding to that record is a newly discovered jawbone belonging to the what may be the oldest Asian-like ungulate (a four-legged hoofed mammal) in Anatolia. It dates to 38 million to 35 million years ago, well before the Grande Coupure, per Science Alert. "This time frame fits everything else we've found in the Balkans," Licht tells NBC. While other Asian animals may have also reached Europe through dry, cool, desert passages in Central Asia, Balkanatolia would've offered a more favorable route. However, as the study published this month in Earth-Science Reviews notes, "past connectivity between individual Balkanatolian islands and the existence of this southern dispersal route remain debated." (Read more discoveries stories.)