CC BY 4.0
Sweetgum
Liquidambar europaea, Mittelmiozän
About the object
The European sweet gum tree Liquidambar europaea grew about 13.5 million years ago in the gallery forests of what is today southern Germany. It was considerably warmer during the Middle Miocene than it is today. At the time of Miocene Climatic Optimum, the earth’s temperature was about 3 to 4 °C warmer. The forests of the northern Alpine foothills were populated by thermophile tree species.
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Species of sweetgum trees are native to North America, Southwest and East Asia. Botanists have puzzled over the close relationship between a number of corresponding plant species found in both North America and East Asia. How is it that closely related species grew so far away from each other on separate continents? Such a disjunct species distribution may be explained with the following broad strokes: during the great radiation of flowering plants in Cretaceous, they were able to colonise large areas of the Northern Hemisphere because the climatic and geographic conditions there were so favourable. It was only after continental drift, mountain folding and climatic changes that large parts of Eurasia ceased to be suitable habitats for these plant families. As a result, they became extinct. Fossils, such as these sweetgum leaves from the Bohlinger Schlucht next to the Schiener Berg, prove that sweetgum trees were historically more widely distributed than they are today.