Radiographic analysis and virtual cleaning of a bioarchaeological remain enclosed in mineral deposits from a limestone cave

In limestone caves, environmental processes often cause alterations of human or animal skeletal remains, complicating classical analytical methods. Exemplary, a proximal femoral skeletal fragment, enclosed by a thick layer of speleothemic calcite deposits, was discovered during the exploration of the Bedara cave in Žumberak, Croatia. An examination without removal of the surrounding mineral deposits, possibly leading to damage of the specimen, was, therefore, desirable. We describe and discuss the applied techniques, including clinical computed tomography, virtual cleaning by a specially developed segmentation protocol using an open-source DICOM viewer, and virtual visualisation and dimensioning using computer-aided design software, so that this “hidden” specimen could be non-invasively examined in great detail. We also report on the circumstances and origin of the find, the results of radiocarbon dating, and its anatomical and taxonomic identification, according to which, the bone fragment belonged to a wild boar (Sus scrofa) from the timeframe of the Middle Eneolithic Retz-Gajary culture in the region (4,781 ± 35 years before present). This study provides a reference for future paleontological and anthropological analyses, seeking to unlock the enormous potential of anatomical studies of comparable skeletal remains that are either petrified or enclosed in speleothemic deposits.