Modern Hippopotamus Species Lived in Europe 560,000 Years Ago and Survived Brutal Ice Age, Study Reveals

The hippopotamus is the second largest mammal on Earth and is considered the springbreaker of the animal world. Named after the Greek word for "river horse," these mammals reside primarily in the lakes and rivers of Africa. However, a new study suggests that these species first dispersed in Europe during the Middle Pleistocene.

Tracing the Roots of Modern Hippos

Together with elephants, hippopotamuses are iconic animals of the savannah grassland ecosystems. Modern species of hippopotamus are especially dependent on the presence of water, serving as indicators of mild winters and humid conditions.

Scientists believe that modern hippopotamuses arose from their African ancestors during the Quaternary, a period in history when these mammals were widespread in Europe. However, their origin and dispersal into Europe are unclear and remain highly debated.

At the Sapienza University of Rome, the Earth Science University Museum is home to the skull of a hippopotamus recovered from the area of Tor di Quinto in Italy. It is one of the most complete hippopotamus specimens known from Pleistocene Europe. Until now, its significance has been unclear due to some uncertainties regarding its age and origin.

In 2021, the skull was restored by a team of scientists led by Beniamino Mecozzi. During the restoration work, original sediments were found inside the cranial and mandible cavities of the fossil, which were sampled for petrographic analyses.

The investigation of the composition of sediments revealed a match to the local Valle Guilia Formation. Experts also combined a review of the old paleontological, archeological, and geological literature published on the Rome basin during the 19th and 20th centuries. From the correlation of this petrographic information, the researchers claimed that the skull was most likely collected from a formation between 560,000 and 460,000 years ago. Observation of cranial and dental morphologies also confirmed the skull's identity as the modern species Hippopotamus amphibius.

This study reveals the skull as the oldest known fossil of the modern hippopotamus species in Europe. The findings shed light on the history of this animal in the continent, reinforcing the hypothesis of an early dispersal during the Middle Pleistocene. The research also bolsters a broad understanding of the deep history of these giant land mammals. Since hippopotamuses are highly influential species within modern and ancient ecosystems, they are valuable indicators of past climate and environmental conditions.

Early Hippopotamus Habitat

The study suggests that the modern hippopotamus species lived about 500,000 years ago during the transition period from the Early to Middle Pleistocene. At this time, the Earth's climate underwent dramatic changes, resulting in longer glacial periods. This condition put the planet into a deep freeze that resulted in the formation of thick ice sheets.

Hippopotamuses likely took refuge in modern-day Italy, Spain, and the Balkan Peninsula when these glaciers advanced, where environmental conditions were relatively mild. These areas also could have enjoyed greater reserves of standing water, which modern-day hippopotamuses need for sleeping and thermoregulation.

The research also suggests that the last hippopotamus on the Italian Peninsula probably died between 128,000 and 73,000 years ago. This means that they could have crossed paths with Neanderthals who lived in Europe thousands of years before Homo sapiens arrived on the continent.