Hippos are the spring breakers of the animal world – follow them, and you’ll find warmth and water. Today, they reside primarily in the lakes and rivers of Africa, where they splash around as the second-largest land animal on Earth. But according to a new study, these sizable creatures once ventured north into Europe and contended with fluctuations in the continent’s glaciers.

The fact that modern hippos, Hippopotamus amphibius, once lived in Europe is well-established science. What scientists still don’t know is how they got there from Africa and their relationship to the long-extinct Hippopotamus antiquus, which may have roamed Europe at the same time.

Scientists also debate when modern hippos first arrived, but the restoration and dating of an important hippo skull found in Rome, Italy, offers up a new answer.

When Did Ancient Hippos Live?

In restoring the skull and jaws, scientists discovered some very old dirt stuck to the teeth and mandible of an ancient hippo. They traced the dirt’s composition to the local Valle Guilia geological formation, which contains sediment between 560,000 years and 460,000 years old.

Thus the hippo would have lived about 500,000 years ago, during the Early-Middle Pleistocene Transition.

Read More: What Are the Oldest Fossils in the World?

Where Did Early Hippos Live?

At this time, the world’s climate went through dramatic changes that resulted in longer glacial periods that put the globe into deep freeze and produced very thick ice sheets. When these glaciers advanced, hippos likely took refuge in modern-day Spain, Italy, and the Balkan Peninsula where conditions were relatively mild. These areas also would have enjoyed greater reserves of standing water, which modern-day hippos require for sleeping and thermoregulation.

According to research, the last hippos to live on the Italian Peninsula probably died between 128,000 years and 73,000 years ago. That means they could have crossed paths with Neanderthals living in Europe but not Homo sapiens, who didn’t arrive on the continent until about 45,000 years ago.

Read More: These Ancient Amphibians Were as Massive as Hippos

Where Did the Hippo Skull Come From?

When the researchers first began working with the hippo fossils, they were lacking some key information – where they had come from. The original label attached to the specimen had been lost, and the catalog held by the Earth Science University Museum at the Sapienza University of Rome contained no location information nor the date of acquisition.

The team drew on past research as well as old maps and photographs to narrow the location down to a former gravel quarry, Cava Montanari, that had operated during the second half of the 19th Century. Today, a riding school sits near the spot, which is surrounded by the Tor di Quinto district of Rome.

Nearby runs the Tiber River, which is the modern expression of an ancient waterway that likely produced the sediment collected from the hippo skull.

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