Dimensional accuracy of structured light scans and 3D prints of various human skeletal elements.

Three-dimensional (3D) structured light scanning is a beneficial documentation technique in forensic anthropology because such models facilitate continued analysis and data sharing; they can also be 3D printed for demonstrative purposes in legal proceedings and training, without risk of damage to the original skeletal material. As its application in forensic anthropology is relatively novel, the aim of the present study is to statistically evaluate the dimensional accuracy of 3D structured light scans and 3D prints for ten bone types, including the cranium, mandible, 2nd cervical vertebra (C2), clavicle, scapula, capitate, 2nd metacarpal, os coxae, femoral head, and patella. Standard linear measurements are acquired in each physical bone, 3D virtual model, and 3D print of the same bone specimen. Variances between measurements of physical, virtual, and printed bones are quantified using the technical error of measurement (TEM), relative TEM (rTEM), and coefficient of reliability (R). Measurements acquired in the virtual models and prints were found to be within ±2 mm average of the same measurements in the physical bones, with a tendency to underestimate true value. rTEM and R values for the virtual clavicle, capitate, scapula and C2, and rTEM for the printed clavicle and capitate, were comparatively less reliable than for other bone types; although all bones were reproduced to within acceptable anthropological error standards (rTEM≤5 %; R≥0.95). This study reaffirms the use of 3D structured light scanning and 3D printing to complement traditional skeletal documentation in forensic anthropology.

An exclusionary screening method based on 3D morphometric features to sort commingled atlases and axes.

In forensic commingled contexts, when the disarticulation occurs uniquely at the atlantoaxial joint, the correct match of atlas and axis may lead to the desirable assembly of the entire body. Notwithstanding the importance of this joint in such scenarios, no study has so far explored three-dimensional (3D) methodologies to match these two adjoining bones. In the present study, we investigated the potential of re-associating atlas and axis through 3D-3D superimposition by testing their articular surfaces congruency in terms of point-to-point distance (Root Mean Square, RMS). We analysed vertebrae either from the same individual (match) and from different individuals (mismatch). The RMS distance values were assessed for both groups (matches and mismatches) and a threshold value was determined to discriminate matches with a sensitivity of 100%. The atlas and the corresponding axis from 41 documented skeletons (18 males and 23 females), in addition to unpaired elements (the atlas or the axis) from 5 individuals, were superimposed, resulting in 41 matches and 1851 mismatches (joining and non-joining elements). No sex-related significant differences were found in matches and mismatches (p = 0.270 and p = 0.210, respectively), allowing to pool together the two sexes in each group. RMS values ranged between 0.41 to 0.77 mm for matches and between 0.37 and 2.18 mm for mismatches. Significant differences were found comparing the two groups (p < 0.001) and the highest RMS of matches (0.77 mm) was used as the discriminative value that provided a sensitivity of 100% and a specificity of 41%. In conclusion, the 3D-3D superimposition of the atlanto-axial articular facets cannot be considered as a re-association method per se, but rather as a screening one. However, further research on the validation of the 3D approach and on its application to other joints might provide clues to the complex topic of the reassociation of crucial adjoining bones.

Virtual reconstruction and geometric morphometric analysis of the Kocabas hominin fossil from Turkey: Implications for taxonomy and evolutionary significance.

The Kocabas specimen comes from a travertine quarry near the homonymous village in the Denizli basin (Turkey). The specimen comprises three main fragments: portions of the right and left parietal and left and right parts of the frontal bone. The fossil was assumed to belong to the Homo erectus s.l. hypodigm by some authors, whereas others see similarities with Middle Pleistocene fossils (Broken Hill 1/Kabwe, Bodo, or Ceprano). Here, we present the first attempt to make a complete reconstruction of the missing medial portion of the frontal bone and a comprehensive geometric morphometric analysis of this bone. We restored the calotte by aligning and mirroring the three preserved fragments. Afterward, we restored the missing portion by applying the thin-plate spline interpolation algorithm of target fossils onto the reconstructed Kocabas specimen. For the geometric morphometric analyses, we collected 80 landmarks on the frontal bone (11 osteometric points, 14 bilateral curve semilandmarks, and 41 surface semilandmarks). The comparative sample includes 21 fossils from different chronological periods and geographical areas and 30 adult modern humans from different populations. Shape analyses highlighted the presence in Kocabas of features usually related to Middle Pleistocene Homo, such as a developed supraorbital torus associated with a relatively short frontal squama and reduced post-toral sulcus. Cluster analysis and linear discriminant analysis classification procedure suggest Kocabas being part of the same taxonomic unit of Eurasian and African Middle Pleistocene Homo. In light of our results, we consider that attributing the Kocabas hominin to H. erectus s.l. may be unwarranted. Results of our analyses are compatible with different evolutionary scenarios, but a more precise chronological framework is needed for a thorough discussion of the evolutionary significance of this specimen. Future work should clarify its geological age, given uncertainties regarding its stratigraphic provenance.

Utilizing augmented reality for reconstruction of fractured, fragmented and damaged craniofacial remains in forensic anthropology.

Forensic anthropologists are often confronted with human remains that have been damaged due to trauma, fire, or postmortem taphonomic alteration, frequently resulting in the fracture and fragmentation of skeletal elements. The augmented reality (AR) technology introduced in this paper builds on familiar 3D visualization methods and utilizes them to make three dimensional holographic meshes of skeletal fragments that can be manipulated, tagged, and examined by the user. Here, CT scans, neural radiance fields (NeRF) artificial intelligence software, and Unreal Engine production software are utilized to construct a three-dimensional holographic image that can be manipulated with HoloLens™ technology to analyze the fracture margin and reconstruct craniofacial elements without causing damage to fragile remains via excessive handling. This allows forensic anthropologists a means of assessing aspects of the biological profile and traumatic injuries without risking further damage to the skeleton. It can also be utilized by students and professional anthropologists to practice refitting before reconstructing craniofacial fragments if refitting is necessary. Additionally, the holographic images can be used to explain complicated concepts in a courtroom without the emotional response related to using bony elements as courtroom exhibits.

Investigating the relationship between cranial bone thickness and diploic channels: A first comparison between fossil Homo sapiens and Homo neanderthalensis.

Diploic veins are part of the circulatory system of the head. They transport venous blood and cerebrospinal fluid and are housed in diploic channels (DCs). DCs are highly variable in terms of their position, extension, and size. These parameters were hypothesized to be related to the variations in cranial vault thickness (CVT). For the first time, we analyzed the spatial relationship between CVT and DCs in a sample of eight H. neanderthalensis and H. sapiens cranial fossils. Using micro-CT scanning data, we constructed color maps of the CVT and visually inspected whether the regional thickness variation was associated with the morphology and distribution of the DC branches. The results showed that when regional bone thickness was below a certain threshold, no DCs or scattered small DC branches were present. Larger DC branches appeared only when the thickness exceeded the threshold. However, once the threshold was reached, further increases in thickness no longer resulted in more or larger DCs. This study also found that our sample of H. neanderthalensis and H. sapiens have different distribution patterns in thin areas, which may affect how their DCs connect with different branches of the middle meningeal vessels. This preliminary study provides evidence for the discussion on the interaction between the cranium, brain, and blood vessels. Future research should include more hominin fossils to better document the variation within each species and possible evolutionary trends among hominin lineages.

Measuring pelvises in 3D surface scans and in MDCT generated virtual environment: Considerations for applications in the forensic context.

Virtual Anthropology (VA) transposes the traditional methods of physical anthropology to virtual environments using imaging techniques and exploits imaging technologies to devise new methodological protocols. In this research, we investigate whether the measurements used in the Diagnose Sexuelle Probabiliste (DSP) and Ischio-Pubic Index (IPI) differ significantly when 3D models of a bone are generated using 3D surface scans (3DSS) and Multidetector Computed Tomography (MDCT) scans. Thirty pelvises were selected from the SIMON identified skeletal collection. An equal ratio of females to males was sought, as well as a good preservation of the bones. The pelvises were scanned using an MDCT scanner and a 3D surface scanner. The measurements of the DSP and IPI methods on the dry bones (referred to as macroscopic measurements here), and then to the 3D models. The intra- and interobserver, using the Technical Error of Measurement (TEM) and relative Technical Error of Measurement (rTEM) error was assessed, and we aimed to observe if the measurements made on the MDCT and 3DSS generated models were significantly different from those taken on the dry bones. Additionally, the normality of the data was tested (Shapiro-Wilk test) and the differences in measurements was evaluated using parametric (Student t-tests) and non-parametric (Wilcoxon) tests. The TEM and rTEM calculations show high intra and interobserver consistency in general. However, some measurements present insufficient inter- and intraobserver agreement. Student t and Wilcoxon tests indicate potentially significant differences of some measurements between the different environments. The results show that especially in the virtual environment, it is not easy to find the right angle for some of the DSP measurements, However, when comparing the measurement differences between dry and virtual bones, the results show that most of the differences are less than or equal to 2.5 mm. Considering the IPI, the landmarks are already difficult to determine on the dry bone, but they are even more difficult to locate in the virtual environment. Nevertheless, this study shows that quantitative methods may be better suited for application in the virtual environment, but further research using different methods is needed.

Sex estimation from virtual models: exploring the potential of stereolithic 3D crania models for morphoscopic trait scoring.

Modern computed tomography (CT) databases are becoming an accepted resource for the practice and development of identification methods in forensic anthropology. However, the utility of 3D models created using free and open-source visualization software such as 3D Slicer has not yet been thoroughly assessed for morphoscopic biological profiling methods where virtual methods of analysis are becoming more common. This paper presents a study that builds on the initial findings from Robles et al. (2020) to determine the feasibility of estimating sex on stereolithic (STL) 3D cranial models produced from CT scans from a modern, living UK population (n = 80) using equation 2 from the Walker's (2008) morphoscopic method. Kendall's coefficients of concordance (KCC) indicated substantial agreement using cranial features scores in an inter-observer test and a video-inter-observer test. Fleiss' Kappa scores showed moderate agreement (0.50) overall between inter-observer sex estimations, and for observer sex estimations in comparison to recorded sexes (0.56). It was found that novice users could virtually employ morphoscopic sex estimation methods effectively on STL 3D cranial models from modern individuals. This study also highlights the potential that digital databases of modern living populations can offer forensic anthropology. Key points: First example of Walker's (2008) method applied to a living UK population.Open-source software is a valuable resource for crime reconstruction approaches.Male scoring bias was observed in method application.Forensic anthropologists would benefit from virtual anthropology training to use and interpret 3D models.Digital databases offer more ethical, diverse, modern populations for future research.

A novel method for sorting and reassociating commingled human remains using deviation analysis.

This study provides an innovative and novel method for sorting commingled human remains at the sacroiliac joint using deviation analyses. Virtual models were created at the University of Tennessee-Knoxville Donated Skeletal Collection from 69 os coxae and 66 sacra using an EinScan-Pro 2× + Handheld Surface Scanner. The shape of the auricular surfaces was analyzed in Geomagic Wrap 2017, and the congruency of the two auricular surfaces was measured using a deviation analysis. ROC curves were performed on a reference sample composed of 200 commingled and non-commingled joint pairs to identify threshold values that could help sort the commingled remains. A validation sample of 225 pairs was subsequently analyzed to demonstrate the efficacy of this new method on a sample of unknown individuals. Statistical analyses demonstrated that the deviation analysis values from sacroiliac joints of commingled pairs were significantly larger than those from non-commingled individuals (p < 0.0001). Based on the selected threshold values, 98%-100% of pairs were correctly sorted and reassociated. This novel and objective technique improves upon previously subjective strategies for sorting commingled remains and, in the future, will be applied to additional joint surfaces.

Drilling down into ethics: A thematic review of ethical considerations for the creation and use of 3D printed human remains in crime reconstruction.

The existing literature contains some exploration of the ethics concerning human remains in forensic and virtual anthropology. However, previous work has stopped short of interrogating the underlying ethical concepts. The question of how people understand and apply these concepts in practice, and what it means to act ethically, remain underexplored. This thematic review explores the ethical considerations that contribute to the creation and use of 3D printed human remains for forensic purposes. The three main branches of ethical theory are outlined to explore how they may apply to forensic practice. Key themes relating to 3D printing human remains in forensic contexts were explored to better understand the ethics landscape, ethical challenges, and the current guidelines in place. Through this thematic review, nine ethics principles were identified as key principles for guiding best practice: anonymity, autonomy, beneficence, consent, context, justice, non-maleficence, proportionality, and transparency. It is suggested that these principles could be incorporated into adaptable guidelines going forward to support ethical practice. The findings also suggest that holistic ethics cognition training may have value in supporting forensic scientists in ethical decision-making, together with procedural and structural design that may promote best practice and reduce cognitive load.

A Comparison of Semilandmarking Approaches in the Analysis of Size and Shape.

Often, few landmarks can be reliably identified in analyses of form variation and covariation. Thus, 'semilandmarking' algorithms have increasingly been applied to surfaces and curves. However, the locations of semilandmarks depend on the investigator's choice of algorithm and their density. In consequence, to the extent that different semilandmarking approaches and densities result in different locations of semilandmarks, they can be expected to yield different results concerning patterns of variation and co-variation. The extent of such differences due to methodology is, as yet, unclear and often ignored. In this study, the performance of three landmark-driven semilandmarking approaches is assessed, using two different surface mesh datasets (ape crania and human heads) with different degrees of variation and complexity, by comparing the results of morphometric analyses. These approaches produce different semilandmark locations, which, in turn, lead to differences in statistical results, although the non-rigid semilandmarking approaches are consistent. Morphometric analyses using semilandmarks must be interpreted with due caution, recognising that error is inevitable and that results are approximations. Further work is needed to investigate the effects of using different landmark and semilandmark templates and to understand the limitations and advantages of different semilandmarking approaches.

Forensic age estimation: comparison and validation of the Iscan method in 3D reconstructions using a surface scanner in a Spanish population.

When investigating a death, post-mortem identification provides with results of great legal and humanitarian significance. The effectiveness of the methods used to estimate age depends on the reference population, considering variables such as sex and ancestry. The aim of this study was to validate the Iscan method to estimate age in a Spanish forensic population, comparing the estimates obtained in dry bones and 3D reconstructions created with a surface scanner. We carried out a cross-sectional study on 109 autopsied corpses (67% male), scanning the sternal end of the right fourth rib in a 3D mesh, using an EinScan-Pro® surface scanner (precision: 0.05 mm). Two observers estimated the phases in dry bones and 3D images according to the Iscan method and to the sex of the subject. The mean age was 57.73 years (SD = 19.12 years;18-93 years). The intra-observer agreement was almost perfect in bones (κ = 0.877-0.960) and 3D images (κ = 0.954), while the inter-observer agreement was almost perfect in bones (κ = 0.813) and substantial in 3D images (κ = 0.727). The correlation with the Iscan phases was very strong in bones (Rho = 0.794-0.820; p < 0.001) and strong in 3D images (Rho = 0.690-0.691; p < 0.001). Both sex-adjusted linear regression models were significant (dry bones: R2 = 0.65; SEE = ± 11.264 years; 3D images: R2 = 0.50; SEE = ± 13.537 years) from phase 4 onwards. An overestimation of age was observed in the first phases, and an underestimation in the later ones. Virtual analysis using a surface scanner in the fourth rib is a valid means of estimating age. However, the error values and confidence intervals were considerable, so the joint use of different methods and anatomical sites is recommended.

A Comparison of Semilandmarking Approaches in the Visualisation of Shape Differences.

In landmark-based analyses of size and shape variation and covariation among biological structures, regions lacking clearly identifiable homologous landmarks are commonly described by semilandmarks. Different algorithms may be used to apply semilandmarks, but little is known about the consequences of analytical results. Here, we assess how different approaches and semilandmarking densities affect the estimates and visualisations of mean and allometrically scaled surfaces. The performance of three landmark-driven semilandmarking approaches is assessed using two different surface mesh datasets with different degrees of variation and complexity: adult human head and ape cranial surfaces. Surfaces fitted to estimates of the mean and allometrically scaled landmark and semilandmark configurations arising from geometric morphometric analyses of these datasets are compared between semilandmarking approaches and different densities, as well as with those from warping to landmarks alone. We find that estimates of surface mesh shape (i.e., after re-semilandmarking and then re-warping) made with varying numbers of semilandmarks are generally consistent, while the warping of surfaces using landmarks alone yields surfaces that can be quite different to those based on semilandmarks, depending on landmark coverage and choice of template surface for warping. The extent to which these differences are important depends on the particular study context and aims.

Icex: Advances in the automatic extraction and volume calculation of cranial cavities.

The use of non-destructive approaches for digital acquisition (e.g. computerised tomography-CT) allows detailed qualitative and quantitative study of internal structures of skeletal material. Here, we present a new R-based software tool, Icex, applicable to the study of the sizes and shapes of skeletal cavities and fossae in 3D digital images. Traditional methods of volume extraction involve the manual labelling (i.e. segmentation) of the areas of interest on each section of the image stack. This is time-consuming, error-prone and challenging to apply to complex cavities. Icex facilitates rapid quantification of such structures. We describe and detail its application to the isolation and calculation of volumes of various cranial cavities. The R tool is used here to automatically extract the orbital volumes, the paranasal sinuses, the nasal cavity and the upper oral volumes, based on the coordinates of 18 cranial anatomical points used to define their limits, from 3D cranial surface meshes obtained by segmenting CT scans. Icex includes an algorithm (Icv) for the calculation of volumes by defining a 3D convex hull of the extracted cavity. We demonstrate the use of Icex on an ontogenetic sample (0-19 years) of modern humans and on the fossil hominin crania Kabwe (Broken Hill) 1, Gibraltar (Forbes' Quarry) and Guattari 1. We also test the tool on three species of non-human primates. In the modern human subsample, Icex allowed us to perform a preliminary analysis on the absolute and relative expansion of cranial sinuses and pneumatisations during growth. The performance of Icex, applied to diverse crania, shows the potential for an extensive evaluation of the developmental and/or evolutionary significance of hollow cranial structures. Furthermore, being open source, Icex is a fully customisable tool, easily applicable to other taxa and skeletal regions.

Virtual anthropology: Forensic applications to cranial skeletal remains from the Spanish Civil War.

Biological and forensic anthropologists face limitations while studying skeletal remains altered by taphonomic alterations and perimortem trauma, such as in remains from the Spanish Civil War. However, virtual anthropology techniques can optimize the information inferred from fragmented and deformed remains by generating and restoring three-dimensional bone models. We applied a low-cost 3D modelling methodology based on photogrammetry to develop novel forensic applications of virtual 3D skull reconstruction, assembly, restoration and ancestry estimation. Crania and mandible fragments from five Spanish Civil War victims were reconstructed with high accuracy, and only one cranium could not be assembled due to extensive bone loss. Virtual mirroring successfully restored reconstructed crania, producing 3D models with reduced deformation and perimortem trauma. High correlation between traditional and virtual craniofacial measurements confirmed that 3D models are suitable for forensic applications. Craniometric databases of world-wide and Spanish populations were used to assess the potential of discriminant analysis to estimate population ancestry. Our protocol correctly estimated the continental origin of 86.7 % of 15 crania of known origin, and despite low morphological differentiation within European populations, correctly identified 54.5 % as Spanish and 27.3 % of them with high posterior probabilities. Two restored crania from the Civil War were estimated as Spanish, and one as a non-Spanish European. Results were not conclusive for one cranium and did not confirm previous archeological hypotheses. Overall, our research shows the potential to assess the presence of foreign volunteers in the Spanish Civil War and highlights the added value of 3D-virtual techniques in forensic anthropology.

3D geometric morphometrics analysis of mandibular fragments of Ouranopithecus macedoniensis from the late Miocene deposits of Central Macedonia, Greece.

OBJECTIVES: To explore mandibular shape differences between Ouranopithecus macedoniensis and a comparative sample of extant great apes using three-dimensional (3D) geometrics morphometrics. Other objectives are to assess mandibular shape variation and homogeneity within Ouranopithecus, explore the effects of size on mandibular shape, and explore the degree of mandibular sexual size dimorphism in Ouranopithecus. MATERIALS AND METHODS: The comparative sample comprises digitized mandibles from adult extant great apes. The 3D analysis includes three datasets: one with landmarks registered on the mandibular corpus and symphysis of mandibles preserving both sides, one on hemimandibles only, and one focused on the ramus and gonial area. Multivariate statistical analyses were conducted, such as ordination analyses (PCA), intra-specific Procrustes distances pairs, pairwise male-female centroid size differences, and correlation analyses. RESULTS: The male and female specimens of Ouranopithecus have mandibular shapes that are quite similar, although differences exist. The Procrustes distances results suggest more shape variation in Ouranopithecus than in the extant great apes. Ouranopithecus shows some similarities in mandibular shape to the larger great apes, Gorilla and Pongo. Moreover, the degree of sexual dimorphism in the small Ouranopithecus sample is greater than any of the great apes. Based on our correlation analyses of principal components (PC) with size, some PCs are significantly correlated with size, with correlation varying from moderate to substantial. DISCUSSION: This study attempted to understand better the variation within the mandibles of O. macedoniensis and the expression of sexual dimorphism in this taxon in more detail than has been done previously. The overall mandibular morphology of Ouranopithecus shows some similarities to those of the larger great apes, which likely reflects similarities in size. Compared to Gorilla and Pongo, O. macedoniensis shows an elevated degree of morphological variation, although limitations relating to sample size apply. Sexual dimorphism in the mandibles of O. macedoniensis appears to be relatively high, seemingly greater than in Gorilla and high even in comparison to Pongo, but this again is possibly in part an artifact of a small sample size.

3D-3D Superimposition of Pubic Bones: Expanding the Anthropological Toolkit for the Pair-Matching of Commingled Skeletal Remains.

Virtual anthropology (VA) has recently produced an additional tool for the analysis of commingled remains and is based on the distance analysis between three-dimensional (3D) models of bones. To date, the pair-matching of the innominate bone through a 3D approach remains partially unexplored. Here, 44 abdominal CT scans (22 males and 22 females) were selected from a hospital database, and the pubic bones were segmented through ITK-SNAP software. The models were hollowed with Viewbox4 to minimize the amount of trabecular bone. The left pubic bones were mirrored and superimposed on the right ones, according to the smallest point-to-point difference between the two surfaces through VAM software. RMS distances between models were calculated through VAM, producing RMS values for 20 matches and 420 mismatches for each sex group. Differences in RMS distance values between matches and mismatches were investigated through Mann−Whitney tests (p < 0.05); the repeatability of the procedure was assessed through absolute and relative technical error measurement (TEM and rTEM). RMS distance values of matches and mismatches were significantly different (p < 0.01) in both groups. The method yielded optimal results with high sensitivity (100.0%) and specificity (99.8% in males, 98.8% in females) rates according to the chosen threshold. This project contributes to the research field of VA with a valuable adjunct that may bolster and strengthen the results of the current visual and osteometric methods through a multidisciplinary approach.

Age estimation based on computed tomography exploration: a combined method.

Despite an extensive number of existing methods, age estimation of human remains is still an unsolved matter in the field of forensic anthropology, especially when it comes to mature adults. The specific aim of this work was to propose a combined method for age estimation, for forensic purposes, by coupling the Suchey-Brooks method and the measure of the pubic bone density. For this purpose, we used an independent test sample comprising 339 CT scans of living individuals aged 15 to 99 years old. Measurement of bone density and staging according to the Suchey-Brooks phases were performed, followed by estimation of ages based on a combined method and an existing virtual reference sample. Results highlighted a significant negative correlation between bone density and age. Good accuracy was obtained for the measurement of pubic bone density for age estimation of men and women, especially concerning mature adults, with an absolute error ranging from 9 to 16 years for all individuals. The authors propose a practical combined method consisting of, first, allocating phases according to the scannographic approach of the Suchey-Brooks method. For phases I to IV, the age estimation is given using the Suchey-Brooks method. For phases V to VI, the pubic bone density measurement is used. Further study will be needed to assess the reproducibility of these results on cadavers and dry bones, as the post-mortem process could interfere with the measurement of mineral bone density.

Testing the reliability of CT scan-based dental wear magnitude scoring.

OBJECTIVES: Digital models are now frequently used in biological anthropology (bioanthropology) research. Despite several studies validating this type of research, none has examined if the assessment of dental wear magnitude based on Computerized Tomography (CT) scans is reliable. Thus, this study aims to fill this gap and assess if dental wear magnitude scoring based on CT scans provides results consistent with scoring based on direct observation of the physical specimens. MATERIALS AND METHODS: Dental wear magnitude from 412 teeth of 35 mandibles originating from the Portuguese Muge and Sado Mesolithic shell-middens was scored. The mandibles were also CT scanned and visualized using 3D Slicer. CT scan-based scoring of dental wear magnitude was then undertaken. Two scoring rounds were undertaken for each observation method (totaling four scoring rounds) and an intra-observer error test was performed. The averaged results of the two observation methods were compared via boxplots with paired cases. RESULTS: Intra-observer error was negligible and non-significant. Scoring results are comparable between the two observation methods. Notwithstanding, some differences were found, in which CT scan assessment generally overestimates dental wear when compared to direct observation. DISCUSSION: Our results generally validate the use of CT scans in studies of dental wear magnitude. Notwithstanding several caveats relating to CT scanning and visualization limitations should be considered to avoid over or under-estimation of dental wear.

[Review and Prospects of Virtual Anthropology].

ABSTRACT: no abstract.

Frontal bone virtual reconstruction and geometric morphometric analysis of the mid-Pleistocene hominin KNM-OG 45500 (Olorgesailie, Kenya).

KNM-OG 45500 is a hominin fossil composed of parts of a frontal bone, left temporal bone, and cranial vault pieces. Since its discovery along the Olorgesailie Formation (Kenya) in 2003, it has been associated with the Homo erectus hypodigm. The specimen, derived from a geological context dated to ca. 900 Ka BP, has been described as a very small individual of probable female sex. However, despite its status as an important hominin specimen, it has not been used in a quantitative comparative framework because of its fragmentary condition. Here, we undertake a virtual reconstruction of the better-preserved fragment, the frontal bone. We additionally apply geometric morphometric analyses, using a geographically diverse fossil and modern human sample, in order to investigate the morphological affinities of KNM-OG 45500. Our results show that the frontal shape of KNM-OG 45500 exhibits similarities with Early Pleistocene fossils from Eurasia and Africa that are assigned to H. erectus sensu lato (s.l.). Its size, on the other hand, is notably smaller than most other Homo erectus fossils and modern humans and similar to the specimens from Dmanisi (Georgia) and to Homo naledi. Taken together, our analyses of the frontal bone suggest a taxonomic attribution of KNM-OG 45500 to H. erectus s.l. and extend even further the range of size variability associated with this taxon around 900 Ka BP.