ETD

• 3D models
• body size
• Hippopotamus
• La Maglianella
• Middle Pleistocene
• morphometry
• taphonomy

Hippopotamus represents one of the most iconic components of the Quaternary megafauna and it has been documented from numerous European localities. Hippopotamuses provide valuable insights into the paleoenvironmental evolution of a geographic area, particularly regarding the evolution of fluvial-lacustrine systems and the severity of climatic oscillations, and into paleobiogeographic patterns in Europe, documenting dispersal events from Africa into the Mediterranean basin.
Although the fossil material is mostly fragmentary and often lacks detailed stratigraphical or geographical information, hippopotamus occurrences are reported from more than one hundred Italian sites spanning from the Early Pleistocene (ca. 1.8 Ma) to the Late Pleistocene (ca. 0.08 Ma).
Among the most significant Italian occurrences, the Middle Pleistocene site of La Maglianella (Rome, Central Italy) stands out for the abundance and preservation of Hippopotamus remains. Despite the richness of specimens and the long story of their discovery (first half of the 20th century), only a small portion of them had previously been described and attributed to the species of Hippopotamus tiberinus, then synonymized with H. antiquus.
Accordingly, the aims of the present study are I) to provide the first systematic catalogue of the La Maglianella specimens, ii) to reconstruct the taphonomic history of the specimens, iii) to provide a comprehensive overview of the hippopotamus assemblage and iv) to digitalize the most valuable specimens for open-source databases.
The entire collection, currently housed at the Museo di Storia Naturale e del Territorio dell’Università di Pisa (Calci, Italy), comprises more than 500 specimens, including complete skeletal elements, bone fragments, and numerous isolated teeth. The remains are attributable to a minimum of six individuals, including five adult left scapulae and a mandible with deciduous dentition.
Ontogenetic variation within the studied sample is documented by differences in dental wear, in the morphology of the scapular spine, and in the presence of homologous bones at different developmental stages, such as an adult humerus with fused epiphyses and a juvenile humerus with unfused epiphyses. Based on comparison with age classes reported for the extant Hippopotamus amphibius, the study collection includes individuals ranging from an approximately six-month-old calf to very old individuals (about 38 years). Notably, the collection also includes ever-growing teeth, such as lower canines and incisors, showing enamel hypoplasia, used here as a proxy to investigate population health and stress indicators. Body mass estimation, based on linear measurements of long bones and astragali, suggests a size range between approximately 1400 kg and 2300 kg, consistent with that of extant Hippopotamus amphibius.
The state of bone preservation varies, but several taphonomic features can be observed: i) bite marks and gnawings, especially on ilia, suggesting scavenging activity by large carnivores, likely hyenas or lions; ii) possible cut marks on different skeletal elements suggesting butchering and disarticulation by humans; iii) striations and shallow grooves on long bone surfaces indicating fluvial transport in shallow waters. A few sediment samples collected from internal cavities of bones revealed the presence of quartz grains, likely responsible for the observed fine surface abrasions. Additional abiotic alterations, including rust and manganese deposits, indicate chemical-physical post-depositional processes. Altogether, these features suggest that the bone assemblage originates from the same stratigraphic unit.
Furthermore, selected specimens were digitalized using both surface scanning and photogrammetry, depending on specimen size, allowing virtual restorations and the creation of a digital database of the collection. These 3D models provide a valuable resource for morphometric analyses, educational purposes and public outreach.
The La Maglianella assemblage represents one of the most abundant and informative hippopotamus records in the Italian Pleistocene. Through systematic cataloguing, paleobiological and taphonomic observations, and the integration of 3D modelling, this study provides new data on a long-neglected fossil site and contributes to expand our knowledge on body size variation, ontogenetic development, and population structure of Middle Pleistocene hippopotamuses. The comprehensive cataloguing of the collection and the digitalization of key-skeletal elements will ensure the long-term accessibility of the collection for comparative studies and further paleobiological research.