A Look from the Inside: MicroCT Analysis of Burned Bones

Abstract

MicroCT imaging is increasingly used in paleoanthropological and zooarchaeological research to analyse the internal microstructure of bone, replacing comparatively invasive and destructive methods. Consequently the analytical potential of this relatively new 3D imaging technology can be enhanced by developing discipline specific protocols for archaeological analysis. Here we examine how the microstructure of mammal bone changes after burning and explore if X-ray computed microtomography (microCT) can be used to obtain reliable information from burned specimens. We subjected domestic pig, roe deer, and red fox bones to burning at different temperatures and for different periods using an oven and an open fire. We observed significant changes in the three-dimensional microstructure of trabecular bone, suggesting that biomechanical studies or other analyses (for instance, determination of age-at-death) can be compromised by burning. In addition, bone subjected to very high temperatures (600°C or more) became cracked, posing challenges for quantifying characteristics of bone microstructure. Specimens burned at 600°C or greater temperatures, exhibit a characteristic criss-cross cracking pattern concentrated in the cortical region of the epiphyses. This feature, which can be readily observed on the surface of whole bone, could help the identification of heavily burned specimens that are small fragments, where color and surface texture are altered by diagenesis or weathering.

Burned bones tell their own stories: A review of methodological approaches to assess heat-induced diagenesis

“…Numerous studies are to be found in the literature based on vibrational spectroscopy techniques, namely Raman (34,39,(61)(62)(63) and Fourier transform infrared (FTIR) (28,34,35,46,50,54,64), X-ray powder diffraction (XRD) (33,50,57,59,(65)(66)(67), X-ray fluorescence (XRF) (37,38,(68)(69)(70), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) (43,55,57,71), scanning electron microscopy (SEM) (15,43,57,(72)(73)(74)(75), nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) (15,76), and computational tomography (CT) (77)(78)(79).…”

A re-evaluation of manner of death at Roman Herculaneum following the AD 79 eruption of Vesuvius

“…By applying a range of analytical methods and imaging modalities, studies have demonstrated that subtle and complex changes occur within the bone structure as a result of thermal exposure (e.g. Boschin et al 2015;Thompson 2015a & b;Ellingham et al 2015Ellingham et al , 2016Cascant et al 2017). Crucially, it has been argued that these changes can be correlated with specific burning conditions, and hence allow for the contextual interpretation of the event itself.…”

Do fish remains provide reliable palaeoenvironmental records? An examination of the effects of cooking on the morphology and chemistry of fish otoliths, vertebrae and scales

“…Morphological alterations seen in the burnt vertebrae and otoliths included changes in colour due to carbonisation (in line with Nicholson 1995), a loss of increment clarity, and a reduction in weight. The reduction of sample weight/density, or "shrinkage" (Shipman et al 1984), is likely due to the thermal denaturation of the collagen component of the structure at temperatures as low as 60ºC (Richter 1986), while burning has been shown to affect bone microstructure significantly at about 400ºC (Boschin et al 2015). Given that otolith or vertebrae weight are commonly used to estimate fish size (Disspain et al 2012;Gabriel et al 2012;Quinn and Deriso 1999), the use of burnt samples would likely underestimate the fish's actual size, thereby resulting in inaccurate fisheries baseline data or an underestimate of meat yield.…”