Balkanatolia: The forgotten continent that sheds light on the evolution
of mammals

Date:
February 22, 2022
Source:
CNRS
Summary:
A team of geologists and palaeontologists has discovered that, some
50 million years ago, there was a low-lying continent separating
Europe from Asia that they have named Balkanatolia. At the time,
it was inhabited by an endemic fauna that was very different from
those of Europe and Asia.

Geographical changes 40 to 34 million years ago connected this
continent to its two neighbors, paving the way for the replacement
of European mammals by Asian mammals.



FULL STORY ==========================================================================
A team of French, American and Turkish palaeontologists and geologists led
by CNRS researchers1 has discovered the existence of a forgotten continent
they have dubbed Balkanatolia, which today covers the present-day
Balkans and Anatolia. Formerly inhabited by a highly specific fauna,
they believe that it enabled mammals from Asia to colonise Europe 34
million years ago. Their findings are published in the March 2022 volume
of Earth Science Reviews.


==========================================================================
For millions of years during the Eocene Epoch (55 to 34 million years
ago), Western Europe and Eastern Asia formed two distinct land masses
with very different mammalian faunas: European forests were home to
endemic fauna such as Palaeotheres (an extinct group distantly related
to present-day horses, but more like today's tapirs), whereas Asia was populated by a more diverse fauna including the mammal families found
today on both continents.

We know that, around 34 million years ago, Western Europe was colonised by Asian species, leading to a major renewal of vertebrate fauna and the extinction of its endemic mammals, a sudden event called the 'Grande
Coupure'.

Surprisingly, fossils found in the Balkans point to the presence of Asian mammals in southern Europe long before the Grande Coupure, suggesting
earlier colonisation.

Now, a team led by CNRS researchers has come up with an explanation
for this paradox. To do this, they reviewed earlier palaeontological discoveries, some of which date back to the 19th century, sometimes
reassessing their dating in the light of current geological data. The
review revealed that, for much of the Eocene, the region corresponding to
the present-day Balkans and Anatolia was home to a terrestrial fauna that
was homogeneous, but distinct from those of Europe and eastern Asia. This exotic fauna included, for example, marsupials of South American affinity
and Embrithopoda (large herbivorous mammals resembling hippopotamuses)
formerly found in Africa. The region must therefore have made up a single
land mass, separated from the neighbouring continents.

The team also discovered a new fossil deposit in Turkey (Bu"yu"kteflek)
dating from 38 to 35 million years ago, which yielded mammals whose
affinity was clearly Asian, and are the earliest discovered in Anatolia
until now. They found jaw fragments belonging to Brontotheres, animals resembling large rhinoceroses that died out at the end of the Eocene.

All this information enabled the team to outline the history of this
third Eurasian continent, wedged between Europe, Africa and Asia,
which they dubbed Balkanatolia. The continent, already in existence 50
million years ago2 and home to a unique fauna, was colonised 40 million
years ago by Asian mammals as a result of geographical changes that have
yet to be fully understood. It seems likely that a major glaciation 34
million years ago, leading to the formation of the Antarctic ice sheet
and lowering sea levels, connected Balkanatolia to Western Europe,
giving rise to the 'Grande Coupure'.

Notes 1Working at the Centre for Research and Teaching in Environmental Geoscience (CNRS/Aix-Marseille Universite'/IRD/INRAE) and at the Centre
for Research on Palaeontology -- Paris (CNRS/Museum national d'Histoire naturelle/Sorbonne Universite'). Another French laboratory, Geosciences
Rennes (CNRS/Universite' Rennes 1) also contributed to this study, along
with Ku"tahya Dumlupınar and Eskişehir Osmangazi Universities (Turkey) and the universities of Washington, Connecticut, Kansas and
Chicago (USA).

2 Balkanatolia may be a relic of Greater Adria, another of the
Mediterranean region's 'forgotten continents', formed over 200 million
years ago, and brought to light by reconstructions of the location of
tectonic plates carried out by Douwe van Hinsbergen et al. and published
in a 2019 paper.

========================================================================== Story Source: Materials provided by CNRS. Note: Content may be edited
for style and length.


========================================================================== Related Multimedia:
*
Maps_of_the_'forgotten_continent'_and_images_of_fossils_and_excavation
location ========================================================================== Journal Reference:
1. Alexis Licht, Gre'goire Me'tais, Pauline Coster, Deniz
İbilioğlu, Faruk Ocakoğlu, Jan Westerweel, Megan
Mueller, Clay Campbell, Spencer Mattingly, Melissa C. Wood,
K. Christopher Beard.

Balkanatolia: The insular mammalian biogeographic province that
partly paved the way to the Grande Coupure. Earth-Science Reviews,
2022; 226: 103929 DOI: 10.1016/j.earscirev.2022.103929 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220222125110.htm

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