No description available.

Forensic anthropologists and taphonomists are often tasked with interpreting the sequence of events from death through decomposition to skeletonisation. Discovery of burnt bone often evokes questions as to the condition of the body prior to the burn event. The purpose of this study was to evaluate features of thermal damage on bones in relationship to the condition of the bone (dry/wet) and progression of decomposition. Twenty-five pigs in various stages of decomposition (fresh, early, advanced, early & late skeletonisation) were exposed to fire for 30 minutes. The skeletal elements were scored and features included: colour change (unaltered, charred, calcined), brown and heat borders, heat lines, delineation, greasy bone, joint shielding, predictable and minimal cracking, delamination and heatinduced fractures. Colour changes were scored according to a ranked percentage scale (0 – 3) and the remaining traits as absent or present (0/1). Cohen’s Kappa statistics evaluated intraand interobserver error. Density plots and frequency distributions were constructed and multiple regression (categorical variables) and transition analysis were employed. The majority (8) of the 13 traits displayed potential to predict decomposition stage from burned remains. An increase in calcined and charred bone occurred synchronously with an advancement in decomposition. The organic composition of bone and presence of flesh affect the characteristics features of burned bone. Greasy bone occurred most often in the early/fresh stages (fleshed bone). Heat borders, heat lines, delineation, joint shielding, predictable and minimal cracking were associated with wet tissue/bone; whereas brown burn/borders, delamination and other heat-induced fractures were associated with early and late skeletonisation. No statistically significant differences were noted among observers for the majority of the traits except for predictable and minimal cracking and heat-induced fractures in the cranium. Heat-induced changes may assist in estimating decomposition stage from unknown, burnt remains and thereby aid in a providing an indication as to the condition of the bone prior to the burn event. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Anatomy / unrestricted

In the anthropological analysis of burned bone, the presence of a white heat line aids in determining a bone’s physical condition prior to burning, distinguishing between those burned fleshed or wet versus dry. However, while the relationship between this thermal signature and a bone’s physical condition has been studied, there is a lack of research concerning the chemical composition of white heat lines. The present study assessed the composition of white heat lines that form on burned bone using Fourier transform infrared spectroscopy (FTIR) with the potassium bromide (KBr) pellet method. The present study examined the effects of soft tissue and the retention of bone’s organic material, including naturally-occurring grease and water, on the development and appearance of a white heat line. Experimental remains consisted of isolated long bones from white-tailed deer (Odocoileus virginianus), elk (Cervus canadensis), sheep (Ovis aries), and pig (Sus scrofa) in five physical conditions – fleshed (fresh bones with adhering soft tissue), very wet (recently defleshed bone, greasy), partially wet (defleshed, slight grease retention), dry (defleshed, naturally degreased), and soaked (formerly dry bone immersed in water). These bones were burned over a wood fire made within a 55-gallon drum. After a visual analysis to evaluate white heat line formation, chemical composition was analyzed by determining spectral peak heights of the carbonate (CO3) ν3 (1415 cm-1), phosphate (PO4) ν3 (1035 cm-1), and amide I (1660 cm-1) vibrational bands. These thermal signatures appear to form superficially, measuring approximately 1.5 mm in depth. Results indicate that white heat lines that formed on fleshed bone contain an increased amount of CO3, PO4, and amide I in comparison to their unburned controls, while those that formed on very wet bone contain decreased amounts instead. These findings further our knowledge of how fire modifies physical remains and the effect that bone’s physical condition prior to burning has on the development of a white heat line and the resulting compositional changes. In order to build upon the results gained from the present study, continuing research is needed to investigate compositional differences between white heat lines that form on fleshed versus very wet bone and to assess bone’s fat content as a possible contributing factor. Additional FTIR research is needed to assess the other vibrational bands of CO3, PO4, and amide that are present in bone.