In the period known as the Eocene, 55 to 34 million years ago, the European and Asian continents existed as distinct land masses with their own unique mammal families, among them rodents, ungulates, and other now extinct species. But the traditional understanding of how these two land masses became one, and the timing of Asian mammals’ eventual arrival in Western Europe, has largely remained a mystery. Now, scientists claim to have discovered a long-forgotten continent that once connected Europe, Africa, and Asia and served as a passage for the animals’ migration. They have named it “Balkanatolia,” a portmanteau of the Balkans and the Turkish peninsula of Anatolia, the present-day areas that once constituted the landmass.
An event known as the “Grande Coupure” has been the leading hypothesis explaining the extinction of native European fauna and the arrival of species from Asia. Scientists describe this event as a combination of lowering sea levels, tectonic shifts, and other factors that created a land bridge between western and eastern regions of Eurasia and precipitated the arrival of Asian species into the European continent.
“People have basically known for decades that Asian mammals invaded Europe somehow,” K. Christopher Beard, a paleontologist and professor at the University of Kansas and co-author of a new study, told NBC News. “What was unknown was: How did they do it? What route did they take?”
The study, published in the journal Earth-Science Reviews and led by Alexis Licht, a scientist at the French National Center for Scientific Research, sheds new light on this hypothesis of mammal migration between Asia and Europe and challenges the established timeline. The paper cites earlier paleontological discoveries, some dating as far back as the 19th century, that underscored a clear separation between western and southeastern European faunas prior to the Grande Coupure.
The researchers examined fossils found in the Balkans dating from the Eocene period that further lend to the theory of an earlier arrival of some species into southern Europe. They also found new fossil deposits in Büyükteflek in central Anatolia that support the existence of an independent land mass characterized by the presence of mammal species distinct from those of both Europe and Asia. This third continent, Balkanatolia, created a pathway for Eurasian migration much earlier in the Eocene period than previously understood. Balkanatolia existed as a low-elevation landmass from the Alpine region to the Lesser Caucasus for much of the Eocene.
“Existing data show that [Balkanatolia] acted as a crossroads between Asia, Europe and Africa, while keeping a unique fauna for millions of years,” Licht said in a statement. “Balkanatolia recalls in many ways the Indo-Australian Archipelago between mainland Asia and the Australia-Papua shelf, and its associated biogeographic province coined ‘Wallacea.’”
The arrival of Asian mammals 41 to 38 million years ago would eventually lead to the extinction of Balkanatolian mammal species, the result of geographic shifts in Anatolia and the Caucasus. A period of major glaciation about 34 million years ago, the origin of the Antarctic ice sheet, significantly lowered sea levels globally. This evaporation of seaways precipitated the Grand Coupure and the eventual connection of Balkanatolia with the rest of Western Europe.
Balkanatolia, as a result, has alternatively been depicted either as a discontinuous archipelago or a wide and continuous island, according to scholarship cited in the study, reflecting periods of partial submergence and reemergence from water. The causes of such tectonic shifts and water levels in “deep time” Eurasia are among things researchers continue to study about Balkanatolia’s impact on the biogeography of the present.
“We have animals on Balkanatolia living side by side that never cohabitate anywhere else on Earth,” Beard told NBC. “How did that happen? How did this strange, unique island get assembled?”
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