New Study Reconstructs the Skull of the Ancient Hippo of Crete

Researchers have digitally reconstructed the skull of Hippopotamus creutzburgi, an ancient dwarf hippo that once roamed Greece’s island of Crete.

Using advanced 3D digital imaging techniques, this marks the first full reconstruction of the species’ skull, providing new insights into its anatomy and evolutionary history. The findings are detailed in a journal focused on archaeology and cultural heritage.

Tracing the journey of H. creutzburgi

During the Pleistocene epoch, hippopotamuses spread across several islands, including Cyprus, Madagascar, Malta, Sicily, and Crete. Fossil evidence suggests that H. creutzburgi descended from Hippopotamus antiquus, a species known to inhabit the Peloponnese, Greece.

Researchers believe that lower sea levels during colder periods allowed a group of H. antiquus to reach Crete, where they adapted to the island’s environment.

Evolution on an island

Following the “island rule,” a concept proposed by biologist Van Valen, the ancestors of H. creutzburgi became smaller over time. Large animals often shrink in island environments due to limited resources, while smaller species may grow larger.

Ολοκληρώθηκε σήμερα στο εργαστήριο μας η συναρμολόγηση ενος σκελετού κρητικού ιπποποταμου (Hippopotamus creutzburgi). Ο καθαρισμός, συντήρηση και συναρμολόγηση του σκελετού, διήρκεσε 7 μήνες. pic.twitter.com/Cld9a5o0n0

— PaleoAthens (@AthensPaleo) October 10, 2024

H. creutzburgi remained on Crete until its extinction, though the exact cause remains uncertain. Potential factors include natural disasters, climate changes, disease, food scarcity, or competition with deer, which arrived on the island during the later Pleistocene.

Challenges in studying fossil remains

Fossil remains of H. creutzburgi are abundant on the Katharó plateau, a site rich in prehistoric findings. However, many of these fossils are poorly preserved, fragmented, or flattened, complicating efforts to study the species. No complete skull of H. creutzburgi had ever been recovered, leaving significant gaps in understanding its morphology.

To address this, researchers Nikolaos Gerakakis and Prof. Dimitrios Makris used four fossil fragments excavated between 1998 and 2002. Employing photogrammetry, a digital imaging method, they reconstructed the skull virtually.

The team relied on Blender, a computer graphics software, to reposition flattened and fragmented parts of the cranium. They followed a retrodeformation technique developed by De Vries et al. in 2022, adapting it for this project.

For the mandible, which was severely deformed, they designed a unique “spider-like” exoskeleton with 23 armatures to restore its original shape.

Key findings

The reconstructed skull reveals that H. creutzburgi shared similarities with African hippopotamuses, Hippopotamus antiquus, and dwarf Malagasy hippopotamuses. Its size was comparable to the Malagasy species or a juvenile African hippopotamus.

This digital model has practical applications beyond research. The team plans to 3D-print the skull for museum exhibitions, including one at the Katharó plateau.

The researchers have also completed a digital reconstruction of the entire skeleton, which has been used to create a physical model at the Laboratory of Vertebrate Paleontology at the National and Kapodistrian University of Athens. The project involved contributions from Prof. George Lyras, Nikolaos Gerakakis, Maria Tsanidou, and Konstantina Kouveli.