During the Eocene epoch, which spanned from 55 million to 34 million years ago, Europe and Asia were home to various types of mammals. But at the end of the Eocene, there was a dramatic shift.
“A lot of the animals that lived in Europe millions of years ago went extinct and were fine,” Baird said. “They were replaced by mammals that obviously had no ancestors in Europe.”
The discovery of fossilized remains of seemingly inexplicable origins indicates that the area has undergone profound changes in palaeobiology over time.
“There were signs that something really strange was going on,” Baird said. “Some of the animals that used to live in the Balkans simply don’t exist anywhere else. And then the groups of animals that lived there didn’t live together anywhere else.”
Scientists have found that for nearly 50 million years, the Balkans existed as an island continent separate from its neighbors. The land mass had its own unique fauna, different from the ones that inhabited Europe and Asia.
About 40 million years ago, a combination of tectonic shifts, ice sheet expansion, and sea-level fluctuations joined the Balkans first to Asia and then linked the continent to southern Europe, creating a giant land bridge across the region.
“At that time, the sea level has decreased by 70 metres [about 230 feet]”It’s huge,” said Alexis Licht, a scientist at the French National Center for Scientific Research, who led the study. “This event alone would have created many land bridges, which is the main hypothesis to explain the relationship between the Balkans and Europe.”
Fossils found in Turkey dated 35 million to 38 million years ago also suggest that the influx of Asian mammals into southern Europe may have occurred earlier than previously thought — several million years before the Great Extinction event, Licht said. Among the Turkic fossils were jaw fragments of Brontotheres, a large rhino-like mammal that died at the end of the Eocene epoch.
“The location in Turkey helped confirm and verify our hypothesis because this time frame fits everything else we found in the Balkans,” Licht said.
But while Balkantolia helps draw a coherent account of the distribution of mammals across Eurasia, many questions remain unanswered. First, it is not well understood what drove the tectonic shifts that altered sea levels at the time, causing parts of the lost continent to be submerged and then re-exposed.
The researchers also hope to find older fossils in the area, dating back more than 50 million years, that could shed light on the early history of Balkantolia. These clues could help scientists understand how the Lost Continent’s group of mammals got there in the first place.
“We have animals in the Balkans that live side by side and don’t co-exist anywhere else on Earth,” Baird said. “How did it happen? How was this strange and unique island assembled?”
Dennis Chow is a reporter for NBC News Science focusing on public science and climate change.
