Hippos Trudged Through Rome 500,000 Years Ago


Ancient Immigrants: Fossils discovered in Rome have proven to be the oldest evidence of modern hippos in Europe. According to new dating, these relics of hippos from the Nile are already 560,000 to 460,000 years old, older than previous finds in Great Britain. The fossils confirm the assumption that these water-loving mammals migrated to Europe early on and lived in extensive lake and river landscapes. According to researchers, the hippos only disappeared from Europe when these water bodies froze during the Ice Age.

While hippos (Hippopotamus amphibius) exclusively inhabit African savannahs with rivers and lakes, they were widespread across Europe until 30,000 years ago. They once lived in the southwest of Germany, among other places, until the last Ice Age, which eventually led to their extinction on European soil. However, while it is clear when hippos disappeared from Europe, there is still debate about when the first of them set foot on our continent from Africa.

A Mysterious Skull

A contentious issue in the debate about European hippos is a fossilized skull from the Tor di Quinto region, north of Rome. The problem is that its exact discovery location has been unclear for 70 years. Some scientists believe it originates from the Cava Montanari quarry, while others consider the Cava Nera Molinario quarry as a more likely location. Fossil remains of red deer and European forest elephants also come from there.

This back-and-forth has led to the well-preserved hippo skull receiving little attention in the reconstruction of hippo distribution in Europe. Despite the quarries potentially containing rocks up to 560,000 years old, a 100,000-year-old skull from Barrington in Britain was considered the oldest evidence of a European hippo. According to the prevalent theory, water-loving mammals should have arrived in Europe much earlier.

The Oldest Hippo Remains Come From Rome

The Roman skull from different perspectives
The Roman skull from different perspectives.

The Italian skull case has undergone a new examination by researchers under the direction of Beniamino Mecozzi from Sapienza University in Rome. When they restored the fossil in 2021, they found inconspicuous sediment residues inside that could only come from its original discovery site. By analyzing these sediments, Mecozzi and his colleagues could determine the exact origin of the skull and, consequently, its age.

The result: The fossil hippo skull comes from Cava Montanari and was deposited there between 560,000 and 460,000 years ago, according to the researchers. “Considering our results, MPUR/V 149 represents the oldest occurrence of H. amphibius in the European fossil record,” write Mecozzi and his colleagues. The skull is by far the oldest evidence of the existence of European hippos, easily surpassing the previous record-holder from Great Britain. Its age also aligns much better with previous theories of hippo migration.

Water Landscapes Were a Prerequisite

Reinforcing the idea of an early dispersal of Hippopotamus amphibius in Europe
Reinforcing the idea of an early dispersal of Hippopotamus amphibius in Europe.

The new dating also reveals more about what the landscape around Rome must have looked like half a million years ago. “Modern hippopotamuses are especially dependent on the presence of water, and hence indicators of humid conditions and mild winters,” say Mecozzi and his team. “Therefore, findings of hippopotamuses in Quaternary deposits indicate the presence of water, in the form of lakes, ponds or rivers.” Only when the climate cooled and these water bodies froze during the last Ice Age were hippos displaced from Europe, and since then, they have only been found in Africa.

Source: PLOS One.