Rhine fossils challenge European prehistory | Science| In-depth reporting on science and technology | DW | 21.05.2012
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Science

Rhine fossils challenge European prehistory

New findings by German scientists have put back the origin of the vital Rhine River from 10 to 15 million years ago. The discovery is changing the way some think about prehistoric Europe.

Fossil antler from the Senckenberg site

Fossil antler from the Senckenberg site

Scientists associated with the Senckenberg nature research society in Germany have published a groundbreaking discovery in the PLoS ONE journal, suggesting that the River Rhine is five million years older than previously thought.

The scientists say fossils from a site near Mainz represent remains from 10 to 15 million years ago. If correct, the middle part of the present-day Rhine would be about five million years older.

It could have implications for the way we think about prehistoric life in Europe.

Tropical Rhine

Madelaine Böhme, the lead author of the study and head of the terrestrial paleoclimatology working group for the Tubingen project, says the fossil findings place the Rhine's origins in the middle Miocene era, rather than in the late Miocene era.

The Middle Miocene era was about 16 to 12 million years ago. It predates Homo sapiens and even the ice ages of the later Pliocene era.

Böhme says that during the middle Miocene era, Europe was very a different place.

"The summer was hot, but precipitation was distributed throughout the year," Böhme told DW.

Based on fossil plant evidence, Böhme says temperatures were about 14 degrees Celsius warmer than they are now. It was a "warm, humid climate."

At the time, ancient relatives of deer and elephants roamed the river valleys. Fossil remains of these animals are part of the study by the German team, which includes scientists from the Senckenberg Center for Human Evolution and Palaeoecology at the University of Tubingen and the Senckenberg Research Institute in Frankfurt.

Sketch of Deinotherium giganteum, prehistoric elephant

Prehistoric elephants similar to this one once roamed the Rhine valley

The scientists analyzed several hundred mammalian fossils and some leaf and wood fossils from the Sprendlingen and Eppelsheim areas near Mainz, which were excavated over the 1980s.

Böhme says vertebrate paleontology in Europe developed in the early 19th Century off the Eppelsheim fossil site, where even the German writer Johann Wolfgang von Goethe took an interest, getting in on the action as a hobby fossil collector.

The find includes a great richness of mammal fossils, supporting a theory of "supersaturated" biodiversity, including 12 species of prehistoric elephants, several species of tigers, and evidence of other species.

Ongoing dispute

By identifying and dating the fossil remains, the Senckenberg team says it was able to prove that the oldest are 15 to 16 million years old, while the youngest were nine to 10 million years old.

It makes the Rhine about five million years older than originally thought.

But according to Böhme the results also imply that the so-called Vallesian crisis - an ecological event said to have killed off a great biodiversity about 10 million years ago - may never have happened.

Böhme describes the implications of the findings as "a paradigm shift."

Jens Franzen, who has spent a significant part of his life working on fossil excavations along the Rhine, says this may be overstating things. Franzen currently volunteers with the Natural History Museum in Basel, Switzerland.

Calling the study "excellent" and "innovative," Franzen told DW the fossil evidence indicates a severe change in the fauna of this time, implying an alteration in environmental conditions, but says "these are ongoing scientific disputes."

Jordi Agusti, a professor at the Institute of Human Paleoecology in Tarragona, Spain, also doubts whether the Senckenberg team's results will spell the end of the Vallesian crisis theory.

"The study doesn't prove anything about sites in Spain," Augusti told DW, adding that there was still "a lot of diversity" to account for.

Changing river

The Senckenberg team also traced pebbles in fossil layers back to the Black Forest region of Germany, the origin of the Rhine in the prehistoric era.

Rhine loop near Boppard

The Rhine River has changed course over the years

Today, the river runs from its origin in Switzerland along the border of Austria, through Germany and the Netherlands before reaching the North Sea. The watershed includes portions of five other European countries, and the river remains a crucial part of Europe's ecology, commerce and culture.

Lead author Madelaine Böhme says the river used to have "a much shorter route", but says it was the main river of Central Europe.

The team hopes to continue its excavations in Sprendlingen and Eppensheim, as well as looking at sites along other rivers.

Author: Sonya Angelica Diehn
Editor: Zulfikar Abbany

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