Hippos roamed central Europe much later than previously thought, as 40,000 years ago, a new study of Ice Age fossils reveals.
Scientists previously thought common hippos – Hippopotamus amphibius – disappeared from central Europe about 115,000 years ago, with the heavy beast currently found only in sub-Saharan Africa.
However, fossils assessed in a new study published in the journal Current Biology suggest these animals lived in Upper Rhine fossil deposits during the midst of the last ice age.
Researchers, including those from the University of Potsdam in Germany, found that hippos continued to inhabit the Upper Rhine Graben in what is now southwestern Germany between approximately 47,000 and 31,000 years ago.
The findings suggest hippos endured far into the last Ice Age, surviving in a region once believed too cold for such heat-loving animals.
They also point to the Upper Rhine fossil deposits as an important continental climate archive.
“The current study provides important new insights which impressively prove that the ice age was not the same everywhere, but local peculiarities taken together form a complex overall picture – similar to a puzzle,” said Wilfried Rosendahl, project leader behind the fossil excavations.
Animal bones have survived in this part of southern Germany for thousands of years in gravel and sand deposits, and are a valuable source for research.
“It’s amazing how well the bones have been preserved. At many skeletal remains, it was possible to take samples suitable for analysis – that is not a given after such a long time,” said Ronny Friedrich, an author of the study.
In the study, scientists examined numerous hippopotamus fossil finds and combined their genomic and age data.
Genome sequences from the samples showed that European ice age hippos are closely related to African hippos living today and belong to the same species.
However, during this time, their populations in Europe likely had very low genetic diversity, the study found.
“The low genome-wide diversity recovered suggests that it belonged to a small, isolated population,” scientists wrote.
Further analysis of the fossil samples suggested heat-loving hippos appeared around the same time frame as species adapted to cold temperatures, such as mammoths and woolly rhinos.
However, the onset of global cooling at the beginning of the last ice age led to “unfavourable conditions”, resulting in the extinction of hippos in western and central Europe.
“It would now be interesting and important to further examine other heat-loving animal species, attributed so far to the last interglacial,” Dr Rosendahl said.
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The once-widespread species that has been declared globally extinct
