A continent forgotten for 40 million years may have just been rediscovered.

A low-lying con­ti­nent that exist­ed around 40 mil­lion years ago and was home to exot­ic fau­na may have “paved the way” for Asian mam­mals to colonise south­ern Europe, accord­ing to new research.

Sand­wiched between Europe, Africa and Asia, the for­got­ten con­ti­nent — which researchers have dubbed “Balka­na­to­lia” — became a gate­way between Asia and Europe when sea lev­els dropped and a land bridge formed around 34 mil­lion years ago.

“When and how the first wave of Asian mam­mals arrived in south­east­ern Europe remains poor­ly under­stood,” write pale­o­ge­ol­o­gist Alex­is Licht and his col­leagues in their new study.

But the result was sim­ply dra­mat­ic. About 34 mil­lion years ago, at the end of the Eocene epoch, large num­bers of native mam­mals dis­ap­peared from west­ern Europe with the emer­gence of new Asian mam­mals, in a sud­den extinc­tion now known as the Great Divide.

How­ev­er, recent fos­sil dis­cov­er­ies in the Balka­ns have turned this time­line on its head, point­ing to a ‘spe­cial’ biore­gion that appears to have allowed Asian mam­mals to colonise south-east­ern Europe up to 5–10 mil­lion years before the Great Divide.

To inves­ti­gate, Licht, of the French Nation­al Cen­tre for Sci­en­tif­ic Research, and his col­leagues re-exam­ined the evi­dence from all known fos­sil sites in the region, which cov­ers the present-day Balkan Penin­su­la and Ana­to­lia, the west­ern­most pro­jec­tion of Asia.

The ages of these sites were revised on the basis of cur­rent geo­log­i­cal data, and the team recon­struct­ed the palaeo­geo­graph­i­cal changes that occurred in the region, which has a “com­plex his­to­ry of episod­ic drown­ing and re-emergence”.

What they found sug­gests that Balka­na­to­lia served as a spring­board for ani­mals to move from Asia to west­ern Europe, with the trans­for­ma­tion of the ancient land­mass from a self-sus­tain­ing con­ti­nent to a land bridge — and the sub­se­quent inva­sion by Asian mam­mals — coin­cid­ing with “dra­mat­ic palaeo­geo­graph­ic changes”.

About 50 mil­lion years ago, the Balka­ns were an iso­lat­ed arch­i­pel­ago, sep­a­rat­ed from neigh­bour­ing con­ti­nents, where a unique col­lec­tion of ani­mals dis­tinct from those of Europe and East Asia flour­ished, the analy­sis says.

Then, a com­bi­na­tion of sea lev­el fall, Antarc­tic ice sheet growth and tec­ton­ic changes linked the Balka­na­to­lian con­ti­nent to west­ern Europe between 40 and 34 mil­lion years ago.

This allowed Asian mam­mals, includ­ing rodents and four-legged hoofed mam­mals (aka ungu­lates), to ven­ture west­ward and invade the Balka­ns, accord­ing to the fos­sil record.

In addi­tion to this record, Licht and his col­leagues also dis­cov­ered frag­ments of a jaw belong­ing to a rhi­noc­er­os-like ani­mal at a new fos­sil site in Turkey, which they dat­ed to around 38 to 35 mil­lion years ago.

The fos­sil is prob­a­bly the old­est Asian-type ungu­late found in Ana­to­lia to date and pre­dates the Great Divide by at least 1.5 mil­lion years, sug­gest­ing that Asian mam­mals were indeed on their way to Europe via the Balkans.

This south­ern route to Europe through the Balka­na­to­lias may have been more favourable for adven­tur­ous ani­mals than cross­ing high lat­i­tude routes through Cen­tral Asia, which at the time were desert steppes.

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