Bone tissue preservation in seawater environment: a preliminary comparative analysis of bones with different post-mortem histories through anthropological and radiological perspectives

Bone taphonomy is a widely investigated topic; however, few data are available concerning marine bone taphonomy, especially on remains recovered from great depths and with short post-mortem intervals. To date, few studies have evaluated the bony changes which occur in seawater compared to samples with different post-mortem histories, and none through a comparative analysis of different approaches. To this purpose, this pilot study aims to examine the influence of seawater on bone preservation compared to other depositional contexts by multiple perspectives. Forty-nine human bone samples (femurs or tibiae) recovered from different environments (sea water, fresh water, outdoor, burial in coffin) were compared by macroscopic, microscopic and bone densitometric approaches. In order to investigate organic and inorganic components, undecalcified and decalcified histology of thin sections was performed. The analyses revealed a well-preserved bone tissue both macroscopically (92%) and microscopically (97% and 95% for undecalcified and decalcified sections). No significant differences were detected from radiological densitometric investigations (BMD = 1.6 g/cm2 ± 0.1), except between old and young individuals (p value < 0.001). Differences were observed for body decomposition and few scavenged samples (3/15). However, even if slight variations were observed, no relation was recorded with the depositional contexts. We found a similar bone preservation in the four environments at the time of recovery, both macroscopically and microscopically, but also with radiological densitometric investigations. Our observations enriched the literature on bone taphonomy, providing data on bone tissue preservation in the early post-mortem period from a multidisciplinary perspective, paving the way for further studies on the topic.