Strange animal fossils helped scientists discover a long-lost continent called 'Balkanatolia'

• A forgotten continent may have formed a bridge between Asia and Europe around 40 million years ago.
• Fossil records show the land once hosted distinct species like marsupials and hippo-like mammals.

Scientists didn't expect to stumble upon the remains of a forgotten continent in the Balkans and Anatolia, a peninsula in western Asia. Instead, they were to hoping to solve a mystery: Fossils from those areas weren't consistent with others found in Europe and Asia.

"There were a few reports of very weird fossil animals and we literally had no idea what they were doing there," Alexis Licht, a research scientist at the French National Center for Scientific Research, told Insider.

Licht and his fellow researchers found evidence of marsupials commonly identified in South America and embrithopods, mammals the size of elephants that resembled hippopotamuses, that were endemic to Africa. They also discovered the remains of pleuraspidotheriids, ancient mammals thought to have disappeared around 56 million years ago, which may have actually survived much longer.

"It made no sense," Licht said, adding, "It was really hard to explain why they were there during a time period that was much younger than expected."

In a study published in the March 2022 volume of Earth-Science Reviews, the scientists reasoned that the animals must have lived on a distinct continent nestled between Europe, Africa, and Asia, which they dubbed "Balkanatolia."

The continent existed at least 50 million years ago as an archipelago, or group of islands. But it may have formed a corridor between Asia and western Europe around 40 million years ago after sea levels fell and retreated, creating a land bridge.

"The fossil findings that we did, plus everything that had been published before, is consistent with the Balkans and Anatolia and being an individual biographic province that was very different from Europe and Asia at that time," Licht said.

"It can be considered a lost continent in the sense that it was one single big land mass with the same animals on it," he added.

Today, the corridor is indistinguishable from Europe and Asia.

Asian mammals may have traversed the continent after it emerged from water

Until recently, scientists believed that Asian mammals colonized western Europe around 34 million years ago, following a sudden extinction event called the Grande Coupure. But the new research demonstrates that mammals inhabited Balkanatolia up to 5-10 million years earlier.

One fossil in particular helped validate this theory. The scientists discovered fragments of a jaw bone belonging to a brontothere, a rhinoceros-like animal, that dated back around 35-38 million years.

"One of the things that's incredible with fossil mammals is that every single species has different teeth," Licht said, adding, "With just a few teeth, you can identify different species in the past, so just finding one jaw is already a lot of information."

The scientists also modeled geographic changes in the area to see how shifting sea levels and plate tectonics may have affected the animals' distribution. They found that parts of the Middle East and areas in eastern Anatolia were submerged until around 40 million years ago, when the ocean retreated, sea levels dipped, and the land was uplifted.

These geographic changes helped connect the continent to western Europe.

"There must have been a barrier that was blocking animals [from reaching] Balkanatolia, and around 37-40 million years ago, this barrier was removed," Licht said.

Once the land appeared, Asian mammals were free to cross over into new territory.

"The dispersal of a particular species doesn't really need a trigger," Licht said, adding, "You just need to provide the adequate environmental condition for the animal to expand its distribution."

Asian mammals eventually became dominant in Balkanatolia, resulting in the extinction of local animals such as the hippo-like embrithopods. That explains both the strange history of fossils in the area and sudden disappearance of certain species, Licht said. Until recently, he added, there weren't enough paleontological records to make this conclusion.

"Because there are few geological studies, we know little about the age of the fossils," he said. "It was hard to make a compilation and draw a synthetic picture of what's going on in this area."