Image: © Alexis Licht & Grégoire Métais
Scientists have identified a long-lost continent that was populated by weird animals some 40 million years ago, according to a new study. This ancient landmass, dubbed “Balkanatolia” because it stretches between the Balkan and Anatolian peninsulas, may have eased the westward passage of Asian mammals into Europe, setting off a major ecological shakeup that reshaped European fauna.
Balkanatolia is now mostly submerged under the eastern end of the Mediterranean Sea, but at the beginning of the Eocene period, an era that ran from 56 to 34 million years ago, the continent rose above the waves due to lower sea levels.
As a temporary land bridge, Balkanatolia “paved the way” to an extinction event known as the Grande Coupure, which ended the Eocene period and reshaped the fauna of Europe some 34 million years ago, reports a new study in Earth-Science Reviews. The fossil record suggests that this period of turmoil was driven by a huge influx of Asian mammals, ranging in size from rhinoceroses to hamsters, that pushed into Europe, placing fatal pressures on several native species.
A team led by Alexis Licht, a research scientist at the Center for Research and Teaching in Environmental Geoscience (CEREGE) in France and affiliate assistant professor at the University of Washington, note that “how and when these Asian mammal clades colonized southeastern Europe remains poorly understood” in the new study. To solve this mystery, the team presented new fossil evidence and conducted a comprehensive review of fossil sites from central Europe to the Caucasus.
“We show that the Eocene distribution of mammals across Eurasia supports a previously unrecognized biogeographic province, designated here as Balkanatolia,” said Licht and his colleagues in the study.
“Balkanatolia has a complex history of episodic drowning and emergence during the Eocene, and it has been depicted either as a discontinuous archipelago or a wide and continuous island,” add the researchers. “It has thus been proposed that Asia-derived mammals dispersed to southeastern Europe along a ‘southern route’ through Balkanatolia.”
However, the idea that Asian mammals traversed through this southern route has been debated based on the fossil records on either side of Balkanatolia, which preserve very different mammal families right up until the Grande Coupure took place 34 million years ago. These seemingly isolated ecosystems suggest that the Asian mammals must have found another way into Europe, otherwise there would be more evidence of them crossing Balkanatolia.
Licht and his colleagues were able to counter these doubts with their discovery of a new fossil site in Turkey that contains Asian odd-toed ungulates from 35 to 38 million years ago, demonstrating that these mammals were migrating through Balkanatolia prior to the Grande Coupure.
In the review of existing research, the team also identified a unique group of mammals that were native to Balkanatolia, including marsupials called metatherians and large hippo-like creatures called embrithopods. The team concluded that such distinctive animals must have evolved in isolation for eons on a landmass that was separated from nearby continents, providing further support for the existence of a Balkanatolian island that eventually became a land bridge nestled in between Asia, Europe, and Africa.
To truly understand the exotic wildlife and geographic significance of Balkanatolia, researchers will need to uncover more fossils from this lost continent and its neighboring landmasses. To that end, the new study offers a new glimpse at this ancient era in which animals from vastly different spheres spectacularly clashed in Europe.