The story
The Grande Coupure, or great break, is a sharp turnover in European mammals about 33.5 million years ago, at the boundary between the Eocene and the Oligocene. It was named in 1909 by the Swiss paleontologist Hans Georg Stehlin, who saw that many native European mammals disappeared from the fossil record at almost the same level, replaced by new types. Gone were many groups such as palaeotheres, related to horses, while new families arrived, including rhinoceroses, true ruminants and many rodents and carnivores.
The cause was climate and geography together. The Antarctic ice sheet formed at about this time, cooling the globe and drying the continents. In Europe, subtropical forests gave way to more open and seasonal woodlands, which suited the migrants from Asia better than the native forest animals. At the same time, a seaway known as the Turgai Strait, which had separated Europe from Asia, retreated, allowing Asian mammals to cross. A large share of European mammal species was replaced in this turnover. The event is the most important change in Europe's mammals in the Paleogene.
Why it mattered
- It shows a global cooling event reaching land animals and reshaping their communities.
- It linked European and Asian mammal faunas into a single Eurasian fauna.
- It marks the end of Eocene mammals in Europe and the start of the more modern Oligocene fauna.
Community notes
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