Scale-sensitive Fractal Analysis Research Articles

An important comparison of software for Scale Sensitive Fractal Analysis : are ancient and new results compatible?

In this paper, I will explore some of the implications of machine learning for archaeological method and theory. Against a back-drop of the rise of Big Data and the Third Science Revolution, what lessons can be drawn from the use of new digital technologies and computational approaches as they are applied to archaeological typologies? In this paper, I explore two key aspects of these approaches - automation and epistemic novelty – and attempt to unravel their implications for archaeological practice. Furthermore, the paper will situate these topics within developments of the philosophy of science and technology and suggest an alternative way to think about machine learning that draws on re-thinking what we mean by machines and automation.

Impact of storage at different thermal conditions on surface characteristics of 3D printed polycaprolactone and poly(ε-caprolactone-co-p-dioxanone) scaffolds

Fused filament fabrication (FFF) is a commonly used method for producing three-dimensional scaffolds using synthetic, degradable polymers. However, there are several variables that must be considered when fabricating devices for clinical use, one of which is storage conditions after printing. While the academic community has examined the impact of FFF on mechanical and thermal properties, there has been less focus on how storage conditions would affect the surface texture of scaffolds. Our hypothesis was that the surface, thermal and physical properties of FFF scaffolds are significantly influenced by the storage conditions. We evaluated the surfaces of FFF poly (ε-caprolactone) (PCL) and poly (ε-caprolactone-co-p-dioxanone) (PCLDX) strands that were stored at 4 °C, 20 °C, and 37 °C for 28 days. We monitored surface texture, physical and thermal changes to understand the effect of storage on the strands. The implementation of scale-sensitive fractal analysis and feature parameters revealed that storage conditions at 37 °C increased the number of hills and dales, as well as the density of peaks and pits compared to 20 °C and 4 °C, for both materials. The feature roughness parameters for PCL had up to 90% higher values than those of PCLDX, which correlated with the physical and thermal properties of the materials. These differences may impact further surface-cell interaction, highlighting the need for further evaluation for faster clinical translation. Our findings emphasize the importance of considering storage conditions in the design and manufacture of FFF scaffolds and suggest that the use of feature roughness parameters could facilitate the optimization and tailoring the surface properties for specific applications.

Surface texture analysis in Toothfrax and MountainsMap® SSFA module: Different software packages, different results?

The scale-sensitive fractal analysis (SSFA) of dental microwear textures is traditionally performed using the software Toothfrax. SSFA has been recently integrated to the software MountainsMap® as an optional module. Meanwhile, Toothfrax support has ended. Before switching to the new module, the outputs between the two software packages must be compared for consistency. We have performed such a test using Bayesian modelling on three datasets including dental surfaces of sheep (Merceron, Ramdarshan, et al., 2016) and guinea pigs (Winkler, Schulz-Kornas, Kaiser, Cuyper, et al., 2019) from controlled feeding experiments, as well as surfaces of quartzite and flint flakes used in an actualistic archeological experiment on cleaning procedures (Pedergnana, Calandra, Bob, et al., 2020). We found that the two software packages calculate significantly different values for the SSFA parameters epLsar, Asfc, HAsfc9 and R2, even when the same settings are used. Nevertheless, the treatments (different diets or cleaning procedures) are discriminated similarly within each dataset. While the new software module is as good as the original software to differentiate treatments, our results imply that the outputs from the two software packages are not directly comparable and, as such, cannot be merged. Surface texture analysts should therefore consider re-analyzing published surfaces before integrating them in their studies.

Characterization of the topography generated by low plasticity burnishing using advanced techniques

This work investigates the surface topography of AISI 304 austenitic stainless steel after low plasticity burnishing through the evaluation of the average surface roughness (Ra), surface texture direction, areal power spectral density (APSD), scale-sensitive fractal analysis and continuous wavelet transform (CWT). The reason for adopting these approaches resides in the fact that traditional amplitude profile parameters neglect dynamic aspects of the process and geometric features of the burnished surface. The direction, periodicity and anisotropy of the surface texture were influenced by number of passes and burnishing speed and, in general, less severe plastic strain conditions tended to produce surfaces with strongly anisotropic characteristics, preferred direction of motifs, with power spectrum indicating a well-defined spatial frequency of peaks, lower fractal complexity and uniform profile distribution. The increase in surface strain severity produced surfaces with more diffuse directional characteristics, which tended to present surface isotropy, higher spatial frequency dispersion of the peaks and higher fractal complexity. Furthermore, the transition from an anisotropic to an isotropic surface can occur without changes in the average surface roughness. The continuous wavelet transforms analysis indicated a dynamic variation on the surface plastic strain when burnishing. The intermediary burnishing speed induced a strong disturbance with loss of periodicity of the roughness profile, resulting in a remarkable influence on the roughness profile in small scales. The increase in number of passes elevated the plastic strain severity, affecting the surface macrogeometric profile. The isotropic surface promoted a less severe stress concentration, reducing the tensile stresses and retarding crack nucleation, thus increasing the fatigue considerably.

About inter- and intra-specific variability of dental microwear texture in rodents: Study of two sympatric Proechimys (Echimyidae) species from the Cacao locality, French Guiana

Material properties of the diet of extant species is reflected by the microwear texture recorded on the enamel tooth surface, a signal that can be useful for estimating the diets of extinct species. Intra-specific dietary variations can occur between sexes or depend on seasonal vegetation cover changes in their habitat. However, these factors cannot, or very rarely, be incorporated within a paleontological context, especially if the fossil record of an extinct species is mainly composed of isolated teeth. In order to assess the effects of these factors on microwear texture features, we studied 42 wild-caught specimens of two sympatric extant species of caviomorph rodents, Proechimys cuvieri and Proechimys guyannensis (Echimyidae, Octodontoidea) from the Cacao area located in French Guiana. Animals were captured between 2007 and 2012, in July and October, along a 1.5 km transect ranging from an old secondary forest to a disturbed forest. We applied a Scale Sensitive Fractal Analysis (SSFA) to the first upper molars of these specimens. Differences of dental microwear textures were found between sexes, between months, and between habitat, leading to one species overlapping in microwear texture parameter space with the other in some cases. The results obtained help identifying which factors might drive intra-population variations in dental microwear texture. Its understanding is indeed a key-step to better interpret the dispersion observed within a given fossil sample set to obtain refined dietary reconstructions. • Dental microwear shows intra- and interspecific differences in sympatric rodents • Intraspecific variability of dental microwear can lead to interspecific overlapping • Dental microwear is not always most impacted by primary component of the diet • Intraspecific variability should be considered in dental microwear interpretations

Areal surface topography representation of as-built and post-processed samples produced by powder bed fusion using laser beam melting

The increasing interest in Additive Manufacturing (AM) is due to its huge advantage in producing parts without any geometrical limitations. It is due to this reason, AM is extensively utilized in automotive, aerospace, medical and dental applications. Despite their popularity, AM is often associated with inferior surface quality which is one of the many reasons why it has failed to fully replace traditional methods. Hence, AM is always followed by a subsequent post-processing step to produce the end-product. To establish control over the surface quality it is first necessary to fully understand the surface behaviour concerning the factors affecting it. In this paper, the focus is mainly on having a better understanding of the surfaces by using scale-sensitive fractal analysis. In addition, the paper documents the influence of build inclination and post-processing in particular shot blasting on surface topography and utilizes a multi-scale approach to identify the most important scale and parameters for characterization. Results of this study reveal that shot blasting has a minimalistic effect on surface features at a large scale as it cannot remove the waviness completely. At smaller scales, blasting imparts additional features on the surface due to the impact of abrasive particles at high pressure. At the intermediate scales, the influence of shot blasting is highest as it successfully eliminates the surface features comprising of partially melted powder particles and stair-step effect.

Methodological implications of intra- and inter-facet microwear texture variation for human childhood paleo-dietary reconstruction: Insights from the deciduous molars of extant and medieval children from France

The present study concerns occlusal dental microwear texture variation on the deciduous molars of children. A description and evaluation of microwear texture variation within facet 9 and a comparison of microwear textures between grinding facets 9 and 11 are presented. The relationship between wear facet surface area and intra-facet microwear texture variability is evaluated. The sample is composed of naturally-exfoliated, taphonomy-free deciduous second molars from twelve extant children and four archaeologically-derived medieval children (for a total of 51 surface measurements). Dental microwear texture analysis (DMTA) was performed using a confocal microscope and scale-sensitive fractal analysis (SSFA) at three standardized locations on facet 9, and one location on facet 11. Facet shape was visually assessed and scored using a headset magnifier (3×) and composite images (20× confocal microscopy). Individuals were assigned to two groups based on a qualitative assessment of facet surface area. Microwear texture variability within facet 9 was high relative to the variability of microwear textures between individuals. No significant inter-facet variation between facets 9 and 11 was detected. No clear differences in microwear and variabilities within facet 9 were found between individuals assigned to small and large facet groups. Our study shows the existence of important intra-facet microwear variation in a sample of children. Intra-facet microwear variation can affect the ability of DMTA to distinguish between diets in contexts with small sample sizes and subtle differences in diet – such as those characterizing dietary transitions in children. Results also suggest non-dietary factors may influence microwear formation during dental exfoliation. A better understanding of intra-facet microwear variation, and when and how to account for it, can improve the application of occlusal DMTA in similar contexts.

Incorporating intraspecific variation into dental microwear texture analysis.

Dental microwear texture analysis (DMTA) quantifies microscopic scar or wear patterns left on teeth by different foods or extraneous ingested items such as grit. It can be a powerful tool for deducing the diets of extinct mammals. Here we investigate how intraspecific variation in the dental microwear of macropodids (kangaroos and their close relatives) can be used to maximize the dietary signal inferable from an inherently limited fossil record. We demonstrate significant intraspecific variation for every factor considered here for both scale-sensitive fractal analysis and International Organization for Standardization surface texture analysis variables. Intraspecific factors were then incorporated into interspecific (dietary) analyses through the use of Linear Mixed Effects modelling, incorporating Akaike's Information Criterion to compare models, and testing models through independent cross-validation. This revealed that for each DMTA variable only a small number of intraspecific factors need to be included to improve differentiation between species. Including specimen as a random factor accounted for stochastic inter-individual variation, and facet, incorporated effects of sampling location. Intraspecific effects of ecoregion, microscope, tooth position and wear were often but not universally important. We conclude that models of microwear data that include intraspecific variation can improve the resolution of dietary reconstructions.

Tribological investigation of copper and AISI 304 steel during dry sliding wear

Copper-based metal matrix (CBMM) composite is used in ball bearings and other tribological components due to significant improvement in thermal and mechanical properties. However, copper alloys based bearings are likely to fail due to severe surface fatigue wear in rolling/sliding condition. To understand the fatigue wear of copper-alloy which is dominated by the evolution of asperity characteristics, the study of topography evolution in dry sliding condition is essential. The purpose of this study is to study the tribological behavior of copper-steel material combination in dry sliding condition. The tribological properties of copper are also compared with AISI 304 steel. Experiments are performed on pin-on-disc tribometer. The AISI 52100 steel disc is used as a counter body during the experiments on AISI 304 and copper pin materials. The effect of normal load on friction coefficient and wear is studied. Surface topographies of the worn surfaces are measured using a 3D optical profiler. Scale-sensitive fractal analysis (SSFA) is performed on worn surfaces to analyze the complexity of the surface. It is found that surface complexity increases with an increase in normal load. At low scale, worn surfaces are rough and can be simplified by applying fractal theory. At lower load, an oxide layer is formed on the copper surface which reduces the direct asperity contacts. At higher load, distortion in the shape of autocorrelation is observed due to an increase in adhesion and plowing wear.

Dental microwear texture analysis of Neandertals from Hortus cave, France

The dental microwear textures of six individuals from Hortus cave, France are compared to Neandertals from different ecological zones and time periods. Molar Phase II facets were scanned using white-light confocal microscopy and scale sensitive fractal analysis yielded enamel surface textural characteristics. The juvenile Hortus III and the older adult Hortus XI exhibit relatively low anisotropy (epLsar) and textural fill volume (Tfv) and are distinct from young adults with higher values. These differences may be related to age, such that only young adults were engaged in the mastication of tough, fibrous vegetation, whereas Hortus XI (50+ years) and Hortus III (6.5–7.9 years) did not. Sub-Phase Vb Hortus individuals exhibit reduced dietary hardness (Asfc) suggesting a greater reliance on soft foods, like meat. Differences between individuals from Hortus cave correspond to both sub-phase variation in climate and intrinsic lifeways.

Brief communication: Dental microwear and diet of Homo naledi.

A recent study of dental chipping suggested that Homo naledi teeth were exposed to "acute trauma" on a regular basis during life, presumably from the consumption of grit-laden foods. This follows debate concerning the etiology of dental chips in South African hominin teeth that dates back more than half a century. Some have argued that antemortem chips result from consumption of hard foods, such as nuts and seeds or bone, whereas others have claimed that exogenous grit on roots and tubers are responsible. Here we examine the dental microwear textures of H. naledi, both to reconstruct aspects of diet of these hominins and to assess the possibility that hard foods (gritty or otherwise) are the culprits for the unusually high antemortem chip incidence reported. We made high-resolution replicas of original molars and found that ten individuals preserve antemortem wear. These were scanned by white-light scanning confocal profilometry and analyzed using scale-sensitive fractal analysis. Resulting data were compared with those published for other fossil hominins and extant non-human primates. Our results indicate that H. naledi had complex microwear textures dominated by large, deep pits. The only known fossil hominin with higher average texture complexity is Paranthropus robustus, and the closest extant primates in a comparative baseline series appear to be the hard-object feeder, Cercocebus atys, and the eurytopic generalist, Papio ursinus. This study suggests that H. naledi likely consumed hard and abrasive foods, such as nuts or tubers, at least on occasion, and that these might well be responsible for the pattern of chipping observed on their teeth.

Dental microwear texture analysis of extant sika deer with considerations on inter-microscope variability and surface preparation protocols

Abstract Recently, dental microwear texture analysis (DMTA) has been applied to various kinds of vertebrates to infer dietary preference. More data are needed on inter-microscope variability to assure the objectivity and repeatability of this method. In the present paper, we investigated inter-microscope variability between two confocal laser microscopes with different specifications, as well as variability due to different protocols applied to the obtained surface before DMTA. We used two different methods of DMTA: the scale sensitive fractal analysis (SSFA) and the surface texture analysis (STA). We collected DMTA data of extant Japanese sika deer populations with varying diets. We found that different protocols produced significantly different results for both SSFA and STA, whereas nearly two thirds of the parameters were not significantly different between the machines when applying the same pre-analysis protocol. Finally, we analyzed DMTA data of 244 sika deer from 11 populations. Twenty nine parameters were significantly different among the populations. Tooth enamel surface of grazing sika deer is dominated by a number of well-aligned scratches, whereas that of browsing deer is more flattened and characterized by more sporadic pits. Therefore, DMTA can identify intraspecific variation in diets, which is smaller than the interspecific dietary variation in extant ruminants.

Buccal dental microwear texture and catarrhine diets.

Two-dimensional dental microwear analyses on occlusal and nonocclusal enamel surfaces have been widely applied to reconstruct the feeding behaviors of extant primates and to infer ecological adaptations in fossil hominins. To date, analyses of dental microwear texture, using three-dimensional, Scale-Sensitive Fractal Analysis approaches has only been applied to occlusal surfaces. Here, for the first time, we apply this 3D proxy to buccal enamel surfaces of catarrhine primates of known feeding ecologies to assess the utility of nonocclusal microwear texture variables as indicators of dietary habits. Buccal microwear texture attributes were collected from high-resolution second molar casts in a sample of seven extant African catarrhine taxa with differing dietary behaviors. A white-light confocal microscope with a 100× objective lens was used to record six microwear texture variables that assess complexity, anisotropy, heterogeneity, and textural fill volume. The physical properties and variation in hardness of ingested foods is reflected by significant differences in the microwear variables on buccal enamel surfaces between species, which is in agreement with early reports using 2D microwear signatures of the same samples. Species that consume hard brittle items showed high buccal enamel complexity and low anisotropy values, while folivorous species that consume tough foods revealed high anisotropy and low complexity enamel patterns. Buccal microwear texture analysis on enamel surfaces clearly reflects diet-related variation in nonhuman primates. Our findings indicate that microwear texture attributes on nonworking enamel surfaces provide an alternative procedure for reconstructing dietary behavior when wear facets on occlusal surfaces are lacking.

Surface-Sensitive Microwear Texture Analysis of Attrition and Erosion

Scale-sensitive fractal analysis of high-resolution 3-dimensional surface reconstructions of wear patterns has advanced our knowledge in evolutionary biology, and has opened up opportunities for translatory applications in clinical practice. To elucidate the microwear characteristics of attrition and erosion in worn natural teeth, we scanned 50 extracted human teeth using a confocal profiler at a high optical resolution (X–Y, 0.17 µm; Z < 3 nm). Our hypothesis was that microwear complexity would be greater in erosion and that anisotropy would be greater in attrition. The teeth were divided into 4 groups, including 2 wear types (attrition and erosion) and 2 locations (anterior and posterior teeth; n = 12 for each anterior group, n = 13 for each posterior group) for 2 tissue types (enamel and dentine). The raw 3-dimensional data cloud was subjected to a newly developed rigorous standardization technique to reduce interscanner variability as well as to filter anomalous scanning data. Linear mixed effects (regression) analyses conducted separately for the dependent variables, complexity and anisotropy, showed the following effects of the independent variables: significant interactions between wear type and tissue type (P = 0.0157 and P = 0.0003, respectively) and significant effects of location (P < 0.0001 and P = 0.0035, respectively). There were significant associations between complexity and anisotropy when the dependent variable was either complexity (P = 0.0003) or anisotropy (P = 0.0014). Our findings of greater complexity in erosion and greater anisotropy in attrition confirm our hypothesis. The greatest geometric means were noted in dentine erosion for complexity and dentine attrition for anisotropy. Dentine also exhibited microwear characteristics that were more consistent with wear types than enamel. Overall, our findings could complement macrowear assessment in dental clinical practice and research and could assist in the early detection and management of pathologic tooth wear.

Minimizing inter-microscope variability in dental microwear texture analysis

A common approach to dental microwear texture analysis (DMTA) uses confocal profilometry in concert with scale-sensitive fractal analysis to help understand the diets of extinct mammals. One of the main benefits of DMTA over other methods is the repeatable, objective manner of data collection. This repeatability, however, is threatened by variation in results of DMTA of the same dental surfaces yielded by different microscopes. Here we compare DMTA data of five species of kangaroos measured on seven profilers of varying specifications. Comparison between microscopes confirms that inter-microscope differences are present, but we show that deployment of a number of automated treatments to remove measurement noise can help minimize inter-microscope differences. Applying these same treatments to a published hominin DMTA dataset shows that they alter some significant differences between dietary groups. Minimising microscope variability while maintaining interspecific dietary differences requires then that these factors are balanced in determining appropriate treatments. The process outlined here offers a solution for allowing comparison of data between microscopes, which is essential for ongoing DMTA research. In addition, the process undertaken, including considerations of other elements of DMTA protocols also promises to streamline methodology, remove measurement noise and in doing so, optimize recovery of a reliable dietary signature.

Dental Surface Texture Characterization Based on Erosive Tooth Wear Processes

The differential diagnosis of dental wear lesions affects their clinical management. We hypothesized that surface texture parameters can differentiate simulated erosion, abrasion, and erosion-abrasion lesions on human enamel and dentin. This in vitro study comprised 2 parts (both factorial 4 × 2), with 4 lesion types (erosion, abrasion, erosion-abrasion, and sound [no lesion; control]) and 2 substrates (enamel and dentin). Flattened/polished dental specimens were used in part 1, whereas natural dental surfaces were used in part 2. Testing surfaces were evaluated in blind conditions, using average surface roughness (Sa) and the following scale-sensitive fractal analysis parameters: area-scale fractal complexity (Asfc), exact proportion length-scale anisotropy of relief (eplsar), scale of maximum complexity (Smc), and textural fill volume (Tfv). Two-way analyses of variance, followed by Fisher’s protected least significant difference tests (α = 0.05), were used to evaluate the effects of lesion and substrate. Classification trees were constructed to verify the strength of potential associations of the tested parameters. In part 1, Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates; only Asfc differentiated erosion and erosion-abrasion enamel lesions (all P < 0.05). The best association of parameters correctly classified up to 84% and 94% of the lesions on enamel and dentin, respectively. In part 2, only Asfc differentiated erosion and erosion-abrasion lesions from the sound (no lesion) control in both substrates, whereas eplsar was able to differentiate erosion from erosion-abrasion (all P < 0.05). The association of parameters correctly classified up to 81% and 91% of the lesions in enamel and dentin, respectively. Asfc, Sa, and Tfv were able to differentiate erosion and erosion-abrasion lesions, despite their complicated surface textures. The association of parameters improved the differentiation of lesions for both enamel and dentin in polished or natural surfaces.

Rodent incisor microwear as a proxy for ecological reconstruction

Increasing attention has been directed toward rodents as a source of paleoenvironmental data due to their discrete home ranges and their ubiquity and abundance in many fossil and archeological assemblages. Further, rodents play a vital role in regulating ecosystem structure and function, and may be closely tied to local habitat. This study assesses the potential of incisor microwear textures of rodents as an environmental proxy and evaluates the extent to which effects of diet, substrate, and habitat can be parsed from the signal. Microwear textures on lower incisors were analyzed using confocal profilometry and quantified using scale-sensitive fractal analysis. Specimens analyzed (n=430) represent omnivorous, herbivorous, and frugivorous species, some arboreal and some terrestrial, collected from African desert, savanna, woodland, and rainforest habitats. Results suggest diet, habitat, and substrate all contribute to rodent incisor microwear patterning, and that this approach holds potential to provide important information about the ecology of past species.

Reconstructing diet and behavior in bioarchaeological groups using incisor microwear texture analysis

Diet and behavioral strategies of modern humans are examined through several indirect and direct lenses. One of the direct lenses is dental microwear texture analysis (DMTA), which examines enamel texture signatures associated with food fracture properties or behavioral regimes. While molar texture signatures are linked to dietary proclivities, those of incisors appear to reflect diet, abrasives, and non-dietary anterior tooth use behaviors. This study builds upon previous research of incisor microwear textures with the addition of six recent modern human groups. This expands the known database of incisor microwear textures to 11 bioarchaeological samples.Dental microwear textures from six bioarchaeological samples (n=142) were collected using a white-light confocal profiler with a 100× objective lens. High-resolution casts of maxillary central incisors were scanned for clean, antemortem microwear textures. Four adjacent scans of the labial surface, nearest the incisal edge, were created, defects were removed, and scans were characterized for microwear textures using SFrax and Toothfrax scale-sensitive fractal analysis software packages.Results show that the samples differ significantly from each other in four texture variables: anisotropy, textural fill volume, heterogeneity, and complexity. These data strengthen previous hypotheses concerning anisotropy and textural fill volume as indicators of non-dietary anterior tooth use and anterior loading regimes, respectively. Moreover, while heterogeneity indicates abrasive load exposure, this measure may be exacerbated by non-dietary behaviors. Complexity is found to be significant in the current study and may reflect a balance between abrasive loads and non-dietary regimes.

Dental microwear profilometry of African non-cercopithecoid catarrhines of the Early Miocene

The Early Miocene of Kenya has yielded the remains of many important stem catarrhine species that provide a glimpse of the East African primate radiation at a time of major faunal turnover. These taxa have been subject to innumerable studies, yet there is still no consensus on their dietary niches. Here we report results of an analysis of dental microwear textures of non-cercopithecoid catarrhines from the Early Miocene of Kenya. Scanning confocal profilometry of all available molar specimens with undamaged occlusal surfaces revealed 82 individuals with unobscured antemortem microwear, representing Dendropithecus, Micropithecus, Limnopithecus, Proconsul, and Rangwapithecus. Scale-sensitive fractal analysis was used to generate microwear texture attributes for each individual, and the fossil taxa were compared with each other using conservative non-parametric statistical tests. This study revealed no discernible variation in microwear texture among the fossil taxa, which is consistent with results from a previous feature-based microwear study using smaller samples. Our results suggest that, despite their morphological differences, these taxa likely often consumed foods with similar abrasive and fracture properties. However, statistical analyses of microwear texture data indicate differences between the Miocene fossil sample and several extant anthropoid primate genera. This suggests that the African non-cercopithecoid catarrhines included in our study, despite variations in tooth form, had generalist diets that were not yet specialized to the degree of many modern taxa.

Experiments in ancient Maya bloodletting: quantification of surface wear on obsidian blades

It is widely accepted that the ancient Maya practiced sacrificial bloodletting to communicate with their dead ancestors and the gods. Implements to draw blood included a variety of tools, including stone blades made of obsidian. Evidence for bloodletting is based on ethnohistoric accounts provided by the Spaniards, ethnographic observation of modern Maya rituals, iconography depicting bloodletting, hieroglyphic references, and the recovery of artifacts from ritual contexts. However, evidence for bloodletting based on the surface wear on the obsidian blades themselves is inconclusive and difficult to identify. Recent work for quantifying use-wear on stone tools using laser scanning confocal microscopy (LSCM) and scale-sensitive fractal analysis, based on relative area (RelA), has led to an experimental program to quantitatively document wear patterns on replicated obsidian tools. Three obsidian blade segments were used to cut raw beef as a proxy for bloodletting. Our results demonstrate that surface roughness on the blade segments can be documented using RelA, but discrimination of the used from the previously unused surface was only possible in one of the three cases; the original surface structure of an obsidian blade plays a role in wear formation and its subsequent documentation based on RelA.