Estimation of population affinity using proximal femoral measurements based on computed tomographic images in the Japanese and western Australian populations.

The present study analyzes morphological differences femora of contemporary Japanese and Western Australian individuals and investigates the feasibility of population affinity estimation based on computed tomographic (CT) data. The latter is deemed to be of practical importance because most anthropological methods rely on the assessment of aspects of skull morphology, which when damaged and/or unavailable, often hampers attempts to estimate population affinity. The study sample comprised CT scans of 297 (146 females; 151 males) Japanese and 330 (145 females; 185 males) Western Australian adult individuals. A total of 10 measurements were acquired in two-dimensional CT images of the left and right femora; two machine learning methods (random forest modeling [RFM]) and support vector machine [SVM]) were then applied for population affinity classification. The accuracy of the two-way (sex-specific and sex-mixed) model was between 71.38 and 82.07% and 76.09-86.09% for RFM and SVM, respectively. Sex-specific (female and male) models were slightly more accurate compared to the sex-mixed models; there were no considerable differences in the correct classification rates between the female- and male-specific models. All the classification accuracies were higher in the Western Australian population, except for the male model using SVM. The four-way sex and population affinity model had an overall classification accuracy of 74.96% and 79.11% for RFM and SVM, respectively. The Western Australian females had the lowest correct classification rate followed by the Japanese males. Our data indicate that femoral measurements may be particularly useful for classification of Japanese and Western Australian individuals.

Population affinity estimation using pelvic measurements based on computed tomographic data acquired from Japanese and Western Australian populations.

The present study analyzes morphological differences in the pelvis of Japanese and Western Australian individuals and investigates the feasibility of population affinity classification based on computed tomography (CT) data. The Japanese and Western Australian samples comprise CT scans of 207 (103 females; 104 males) and 158 (78 females; 80 males) adult individuals, respectively. Following volumetric reconstruction, a total of 19 pelvic landmarks were obtained on each sample, and 11 measurements, including two angles, were calculated. Machine learning methods (random forest modeling [RFM] and support vector machine [SVM]) were used to classify population affinity. Classification accuracy of the two-way models was approximately 80% for RFM: the two-way sex-specific and sex-mixed models for SVM achieved > 90% and > 85%, respectively. The sex-specific models had higher accurate classification rates than the sex-mixed models, except for the Japanese male sample. The classification accuracy of the four-way sex and population affinity model had an overall classification accuracy of 76.71% for RFM and 87.67% for SVM. All the correct classification rates were higher in the Japanese relative to the Western Australian sample. Our data suggest that pelvic morphology is sufficiently distinct between Japanese and Western Australian individuals to facilitate the accurate classification of population affinity based on measurements acquired in CT images. To the best of our knowledge, this is the first study investigating the feasibility of population affinity estimation based on CT images of the pelvis, which appears as a viable supplement to traditional approaches based on cranio-facial morphology.

Estimation of ancestry from cranial measurements based on MDCT data acquired in a Japanese and Western Australian population.

The estimation of ancestry is important not only towards establishing identity but also as a required precursor to facilitating the accurate estimation of other attributes such as sex, age at death, and stature. The present study aims to analyze morphological variation in the crania of Japanese and Western Australian individuals and test predictive models based on machine learning for their potential forensic application. The Japanese and Western Australian samples comprise computed tomography (CT) scans of 230 (111 female; 119 male) and 225 adult individuals (112 female; 113 male), respectively. A total of 18 measurements were calculated, and machine learning methods (random forest modeling, RFM; support vector machine, SVM) were used to classify ancestry. The two-way unisex model achieved an overall accuracy of 93.2% for RFM and 97.1% for SVM, respectively. The four-way sex and ancestry model demonstrated an overall classification accuracy of 84.0% for RFM and 93.0% for SVM. The sex-specific models were most accurate in the female samples (♀ 95.1% for RFM and 100% for SVM; ♂91.4% for RFM and 97.4% for SVM). Our findings suggest that cranial measurements acquired in CT images can be used to accurately classify Japanese and Western Australian individuals into their respective population. This is the first study to assess the feasibility of ancestry estimation using three-dimensional CT images of the skull.

Sex estimation of frontal sinus volume from computed tomography scans in a Western Australian adult population.

With the increasing use of radiological three-dimensional imaging, different metric and morphological aspects of the frontal sinuses (FS) have been examined relative to their potential to aid human identification, including sex estimation. The aim of this study is to assess the validity of the metric analysis of the FS volume for estimating sex in a Western Australian (WA) adult population, following the Michel et al. (2015) method. The right, left and total frontal sinus volume (TFSV) from 99 computed tomography scans (47 males and 52 females) of WA individuals aged 18-40 years were three-dimensionally reconstructed using OsiriX® and their volumes acquired in mm3. Sexual dimorphism in the TFSV was tested, and the accuracy of the Michel et al. (2015) formulae was calculated. Population-specific regression equations were also produced. There was a significant difference between the mean TFSV in males and females. The classification accuracy derived from the Michel et al. (2015) formulae was 59.6%. The WA-specific logistic regression analysis yielded an accuracy of 57.2%. The low accuracy rates preclude the use of the sex estimation method in the WA population, but the volume analysis confirmed the individual variability of the frontal sinuses, which may be useful for personal identification.

Cult, herding, and 'pilgrimage' in the Late Neolithic of north-west Arabia: Excavations at a mustatil east of AlUla.

Since the 1970s, monumental stone structures now called mustatil have been documented across Saudi Arabia. However, it was not until 2017 that the first intensive and systematic study of this structure type was undertaken, although this study could not determine the precise function of these features. Recent excavations in AlUla have now determined that these structures fulfilled a ritual purpose, with specifically selected elements of both wild and domestic taxa deposited around a betyl. This paper outlines the results of the University of Western Australia's work at site IDIHA-0008222, a 140 m long mustatil (IDIHA-F-0011081), located 55 km east of AlUla. Work at this site sheds new and important light on the cult, herding and 'pilgrimage' in the Late Neolithic of north-west Arabia, with the site revealing one of the earliest chronometrically dated betyls in the Arabian Peninsula and some of the earliest evidence for domestic cattle in northern Arabia.

Validation of the Iscan method in clinical MSCT scans specific to an Australian population.

The transposition of traditional biological profiling methods to virtual skeletal reconstructions represents a relatively novel practice that is proving to be versatile in a variety of forensic contexts. Widespread acknowledgement of the disadvantages associated with archaeological and/or other non-contemporary skeletal collections has prompted an increase in the use of medical imaging modalities for the purposes of formulating population-specific reference standards used to estimate characteristics such as chronological age. The primary aim of the present study is to statistically evaluate the reproducibility of assessment and thereafter develop age estimation standards based on the morphoscopic evaluation of the fourth right sternal rib following the phase ageing method developed as reported by Iscan et al. (J Forensic Sci 29:1094-1104, 1984, J Forensic Sci 30:853-863, 1985) in clinical multi-slice computed tomography (MSCT) scans. A total of 335 MSCT scans representing Western Australian individuals between 10 and 80 years of age (179 male and 156 female) were retrospectively reconstructed and analysed in OsiriX following the Iscan et al. sex-specific standards (J Forensic Sci 29:1094-1104, 1984, J Forensic Sci 30:853-863, 1985) for the fourth right rib. Regression and transition analyses are employed to generate standards for the estimation of chronological age and modelling of thoracic senescence, respectively. The method was also applied to right ribs three and five to evaluate intercostal variance in age-related metamorphosis. Intra- and inter-observer accordance is 'substantial' (K = 0.76) and 'almost perfect' (K = 0.825), respectively. Intercostal variances between ribs three to five were observed in the male sample only. Multiple regression using phase scores from all three ribs produced models with the highest predictive accuracy (± 10.04 years for males and ± 9.81 years for females). The transition analyses demonstrate comparable levels of age-related morphological change across ribs and male and female samples. This study presents a novel set of reference standards for a contemporary Australian population and further demonstrates the utility of virtual analysis in forensic anthropology.

Geometric morphometrics on juvenile crania: Exploring age and sex variation in an Australian population.

For medico-legal forensic practitioners the identification of unknown remains is an important part of any investigation, often predicated on having accurate estimations of age and sex. In considering the specific skeletal elements available to facilitate such biological information, the cranium is frequently targeted for analysis, as it exhibits marked traits of sexual dimorphism, and also has a predictable pattern of growth. There are, however, instances where it may not be possible to estimate skeletal sex, especially in the juvenile skeleton. There is still considerable uncertainty surrounding the age at which the human cranium is quantifiably dimorphic. The aim of the present study is to explore age and sex variation in three-dimensionally reconstructed MDCT scans of the juvenile cranium. The study sample comprises 152 juvenile crania from a Western Australian population; a total of 52 three-dimensional landmarks are acquired and analyzed using Procrustean geometric morphometrics. Group discrimination is assessed between sexes and across age classes. Results demonstrate that sexual dimorphism and age variation is discernible through geometric morphometric analysis of form, size and shape. Relative to sex and age, size is found to be generally equivalent to, or even more accurate than, shape data. There is little quantifiable sexual dimorphism in individuals younger than 12years of age with most variation related to age; discrimination improves with increasing age, with average hit rate (HR) values increasing from just over 50% (52-58%) to more than 90% (93-94%) accuracy at 18years. In contrast, differences between contiguous age classes follow the opposite trend and tend to be larger in prepubertal groups, while becoming progressively smaller in older age classes. This study demonstrates that simple linear interlandmark distances describing overall cranial size may provide a simple option for preliminary classifications of age and sex in skeletal remains of forensic interest. However, although recombining size and shape to perform analyses using form generally does not appreciably improve predictive accuracy, it potentially contributes to increased confidence in group assessment (especially for sex) and thus offers a promising, albeit complex, type of information to discriminate groups based on cranial size and/or shape.

Quantification of spheno-occipital synchondrosis fusion in a contemporary Malaysian population.

Timing of fusion of the spheno-occipital synchondrosis (SOS) is correlated with age. Previous research, however, has demonstrated variation in the timing of closure among different global populations. The present study aims to quantify the timing of SOS fusion in Malaysian individuals as visualised in multi-detector computed tomography (CT) scans and to thereafter formulate age estimation models based on fusion status. Anonymised cranial CT scans of 336 males and 164 females, aged 5-25 years, were acquired from the National Institute of Forensic Medicine, Hospital Kuala Lumpur and Department of Diagnostic Imaging, Hospital Sultanah Aminah. The scans were received in DICOM format and reconstructed into three-dimensional images using OsiriX. The SOS is scored as open, fusing endocranially, fusing ectocranially or completely fused. Statistical analyses are performed using IBM SPSS Statistics version 24. Transition analysis (Nphases2) is then utilised to calculate age ranges for each stage. To assess the reliability of an observation, intra- and inter-observer agreement is quantified using Fleiss Kappa and was found to be excellent (κ=0.785-0.907 and 0.812). The mean (SD) age for complete fusion is 20.84 (2.84) years in males and 19.78 (3.35) years in females. Transition ages between Stages 0 and 1, 1 and 2, and 2 and 3 in males are 12.52, 13.98 and 15.52 years, respectively (SD 1.37); in females, the corresponding data are 10.47, 12.26 and 13.80 years (SD 1.72). Complete fusion of the SOS was observed in all individuals above the age of 18 years. SOS fusion status provides upper and lower age boundaries for forensic age estimation in the Malaysian sample.

Age estimation in a sub-adult Western Australian population based on the analysis of the pelvic girdle and proximal femur.

The accurate and precise estimation of skeletal age by a forensic anthropologist is both a professional and judicial requirement. When unknown skeletal remains are referred to the anthropologist, the estimation of the requisite biological attributes (e.g., age and sex) should accordingly be based on the application of population-specific standards (statistical data). Deviations from the latter practice may result in reduced accuracy and compromised identification. Towards informing appropriate forensic practice, the aim of the present study is to develop statistically quantified age estimation models for a contemporary sub-adult Western Australian population based on the timing of fusion in the os coxa and proximal femur. The study sample comprises 562 known age and sex MDCT scans (292 male, 270 female) representing contemporary Western Australian individuals birth through 30 years of age. Scans are viewed in multi-planar reconstructed (MPR) and/or three-dimensionally reconstructed images using OsiriX®. Fusion status is scored according to a three-stage system across a total of nine sites in the proximal femur and os coxae. Observer accordance, bilateral asymmetry and sex-specific variation in fusion timing are statistically quantified. Polynomial regression is used to formulate age prediction models; transition analysis is used to calculate age ranges and determine the mean age for transition between an unfused, fusing and fused status. Observer accordance in stage assignation is acceptable (Ï°=0.79) and there is no significant bilateral variation in fusion timing. It was found that the mean age of commencement of fusion is significantly earlier (∼2 years) in females. The accuracy (SEE) of the polynomial models ranges from ±3.29 to ±3.80 years and the transition analysis shows that fusion of the iliac crest is delayed in comparison to other attributes of os coxa and proximal femur. Results of the present study confirm that the pelvic girdle and proximal femur can be used to accurately estimate chronological age in the study population.

Accuracy of a cut-off value based on the third molar index: Validation in an Australian population.

According to Recommendation N°196 of the Australian Law Reform Commission (ALRC), the age at which a child reaches adulthood for the purposes of criminal law should be 18 years in all Australian jurisdictions. With specific reference to age at majority, the only tooth with development spanning adolescence (and thus the legally relevant 18 years of age) is the third molar, which limits the number of methods that can be applied from those available in the published literature. The aim of the present study is to test the accuracy of the third molar index (I3M=0.08), based on the correlation between chronological age and normalized measures of the open apices and height of the third mandibular molar, in order to assess the legal adult age of 18 years. Digital orthopantomographs of 143 living Australian subjects (72 boys and 71 girls) are analyzed. The results demonstrate that the sensitivity is 0.90 in boys and 0.90 in girls; associated specificity values are 0.85 and 0.87 respectively. We conclude that the cut-off value of I3M=0.08 is statistically robust and thus valid for forensic application in an Australian population.

Skeletal age estimation in a contemporary Western Australian population using the Tanner-Whitehouse method.

Various age estimation techniques have been utilised in Australia to evaluate the age of individuals who do not have documentation to determine legal majority/culpability. These age estimation techniques rely on the assessment of skeletal development as visualised in radiographs, CT scans, MRI or ultrasound modalities, and subsequent comparison to reference standards. These standards are not always population specific and are thus known to be less accurate when applied outside of the original reference sample, leading to potential ethical implications. Therefore, the present study aims to: (i) explore the variation in developmental trajectories between the established Tanner-Whitehouse (TW) age estimation standards and a Western Australian population; and (ii) develop specific hand-wrist age estimation standards for the latter population. The present study examines digital anterior-posterior hand-wrist radiographs of 360 individuals 0 to 24.9 years of age, equally represented by sex. Each radiograph was assessed using the RUS, Carpal and 20-bone methods of Tanner et al. The standard error of the estimate (SEE) was calculated for each method (range: ♀ SEE ±0.4-11.5 years; ♂ SEE ±0.9-10.1 years). The most accurate method was TW3 RUS for females and the TW2 Carpal system for males. The 50th centile skeletal maturity scores for each year age group were plotted against average chronological age to produce polynomial regression standards with a demonstrated accuracy of (♀ SEE ±0.09-3.46 years; ♂ SEE ±0.02-3.42 years) for females and males, respectively. The standards presented here can be used in future forensic investigations that require age estimation of hand-wrist bones in a Western Australian population, however, they are not appropriate for establishing age of majority (18 years), as skeletal maturity was attained on average earlier than 15 years of age in both sexes for all three systems examined.

CT evaluation of timing for ossification of the medial clavicular epiphysis in a contemporary Western Australian population.

The clavicle is the first bone to ossify in the developing embryo and the last to complete epiphyseal union. It is the latter sustained period of growth that has attracted the interest of skeletal biologists and forensic practitioners alike, who collectively recognize the important opportunity this bone affords to estimate skeletal age across the prenatal to early adult lifespan. Current research is largely directed towards evaluating the applicability of assessing fusion in the medial epiphysis, specifically for determining age of majority in the living. This study aims to contribute further insights, and inform medicolegal practice, by evaluating the Schmeling five-stage system for the assessment of clavicular development in a Western Australian population. We retrospectively evaluated high-resolution multiple detector computed tomography (MDCT) scans of 388 individuals (210 male; 178 female) between 10 and 35 years of age. Scans are viewed in axial and multiplanar reconstructed (MPR) images using OsiriX®. Fusion status is scored according to a five-stage system. Transition analysis is used to calculate age ranges and determine the mean age for transition between an unfused, fusing and fused status. The maximum likelihood estimates (in years) for transition from unfused to fusing is 20.60 (male) and 19.19 (female); transition from fusing to complete fusion is 21.92 (male) and 21.47 (female). Results of the present study confirm the reliability of the assessed method and demonstrate remarkable consistency to data reported for other global populations.

Estimation of sex from the metric assessment of digital hand radiographs in a Western Australian population.

The forensic anthropologist is responsible for contributing to the identification of an unknown by constructing a biological profile from their skeletal remains. Towards achieving this goal, anthropologists can apply population and temporally specific standards with known error margins to morphometric data collected from a decedent. Recent research relating to the formulation of sex estimation standards has focussed on the assessment of bones other than the traditionally favoured pelvis and cranium, such as long bones of the appendicular skeleton. In particular, sex estimation standards based on morphometric data from metacarpals and phalanges have reported classification accuracy rates of 80% (and above) based on a narrow range of populations. The purpose of this study is to provide population-specific hand bone sex-estimation standards for a contemporary Western Australian population. The present study examines digital right hand radiographs of 300 adults of known age, equally represented by sex. A total of 40 measurements were taken in each hand (metacarpals and proximal phalanges); the measurements were then analysed using univariate statistics and cross-validated direct and stepwise discriminant function analysis. All hand bone measurements were significantly sexually dimorphic, with a tendency for the width measurements to express a higher degree of dimorphism than the length measurements. A maximum cross-validated classification accuracy of 91% was achieved with a sex bias of -6%. The standards presented here can be used in future forensic investigations that require sex estimation of hand bones in a Western Australian population.

Morphometric analysis of pelvic sexual dimorphism in a contemporary Western Australian population.

Requisite to routine casework involving unidentified skeletal remains is the formulation of an accurate biological profile, including sex estimation. Choice of method(s) is invariably related to preservation and by association, available bones. It is vital that the method applied affords statistical quantification of accuracy rates and predictive confidence so that evidentiary requirements for legal submission are satisfied. Achieving the latter necessitates the application of contemporary population-specific standards. This study examines skeletal pelvic dimorphism in contemporary Western Australian individuals to quantify the accuracy of using pelvic measurements to estimate sex and to formulate a series of morphometric standards. The sample comprises pelvic multi-slice computer tomography (MSCT) scans from 200 male and 200 female adults. Following 3D rendering, the 3D coordinates of 24 landmarks are acquired using OsiriX® (v.4.1.1) with 12 inter-landmark linear measurements and two angles acquired using MorphDb. Measurements are analysed using basic descriptive statistics and discriminant functions analyses employing jackknife validation of classification results. All except two linear measurements are dimorphic with sex differences explaining up to 65 % of sample variance. Transverse pelvic outlet and subpubic angle contribute most significantly to sex discrimination with accuracy rates between 100 % (complete pelvis-10 variables) and 81.2 % (ischial length). This study represents the initial forensic research into pelvic sexual dimorphism in a Western Australian population. Given these methods, we conclude that this highly dimorphic bone can be used to classify sex with a high degree of expected accuracy.

Brief communication: timing of spheno-occipital closure in modern Western Australians.

The spheno-occipital synchondrosis is a craniofacial growth centre between the occipital and sphenoid bones-its ossification persists into adolescence, which for the skeletal biologist, means it has potential application for estimating subadult age. Based on previous research the timing of spheno-occipital fusion is widely variable between and within populations, with reports of complete fusion in individuals as young as 11 years of age and nonfusion in adults. The aim of this study is, therefore, to examine this structure in a mixed sex sample of Western Australian individuals that developmentally span late childhood to adulthood. The objective is to develop statistically quantified age estimation standards based on scoring the degree of spheno-occipital fusion. The sample comprises multidetector computed tomography (MDCT) scans of 312 individuals (169 male; 143 female) between 5 and 25 years of age. Each MDCT scan is visualized in a standardized sagittal plane using three-dimensional oblique multiplanar reformatting. Fusion status is scored according to a four-stage system. Transition analysis is used to calculate age ranges for each defined stage and determine the mean age for transition between an unfused, fusing and fused status. The maximum likelihood estimates for the transition from open to fusing in the endocranial half is 14.44 years (male) and 11.42 years (female); transition from fusion in the ectocranial half to complete fusion is 16.16 years (male) and 13.62 years (female). This study affirms the potential value of assessing the degree of fusion in the spheno-occipital synchondrosis as an indicator of skeletal age.

Sex estimation using anthropometry of feet and footprints in a Western Australian population.

An important component of forensic investigation is the identification of deceased (and increasingly living) individuals, which is often the role of the forensic anthropologist. One of the most valuable steps towards identification is via a biological profile, developed through the application of population specific standards. In disaster victim identification scenarios, fleshed feet are often recovered in footwear; footprints are another potential source of trace evidence found at crime scenes. In medico-legal investigations, feet and footprints can be useful for extrapolating living height, it is thus expedient to determine whether sex can be estimated from the same anthropometric data. The aim of the present study is to develop accurate sex estimation standards for a contemporary Western Australian population from measurements of the feet and footprints. The sample comprises 200 adults (90 males, 110 females). Three bilateral linear measurements were taken from each foot and seven bilateral measurements were acquired from static footprints obtained using a Podograph. A precision test was first conducted to assess data accuracy and reliability. Measurement data are then analysed using a range of parametric statistical tests. Results show that males were significantly (P<0.001) larger than females for all foot and footprint measurements; cross-validated sex classification accuracies ranged from 71% to 91%. Although in many instances the sex bias was large (>±5%), this study provides viable alternatives for estimating sex in Western Australian individuals with accuracy equivalent to established standards developed from foot bones.

Estimation of stature using anthropometry of feet and footprints in a Western Australian population.

The aim of the study is to develop accurate stature estimation models for a contemporary Western Australian population from measurements of the feet and footprints. The sample comprises 200 adults (90 males, 110 females). A stature measurement, three linear measurements from each foot and bilateral footprints were collected from each subject. Seven linear measurements were then extracted from each print. Prior to data collection, a precision test was conducted to determine the repeatability of measurement acquisition. The primary data were then analysed using a range of parametric statistical tests. Results show that all foot and footprint measurements were significantly (P < 0.01-0.001) correlated with stature and estimation models were formulated with a prediction accuracy of ± 4.673 cm to ± 6.926 cm. Left foot length was the most accurate single variable in the simple linear regressions (males: ± 5.065 cm; females: ± 4.777 cm). This study provides viable alternatives for estimating stature in a Western Australian population that are equivalent to established standards developed from foot bones.

Estimation of sex from cranial measurements in a Western Australian population.

It is widely accepted that the most accurate statistical estimations of biological attributes in the human skeleton (e.g., sex, age and stature) are produced using population-specific standards. As we previously demonstrated that the application of foreign standards to Western Australian individuals results in an unacceptably large sex bias (females frequently misclassified), the need for population-specific standards is duly required and greatly overdue. We report here on the first morphometric cranial sexing standards formulated specifically for application in, and based on the statistical analysis of, contemporary Western Australian individuals. The primary aim is to investigate the nature of cranial sexual dimorphism in this population and outline a series of statistically robust standards suitable for estimating sex in the complete bone and/or associated diagnostic fragments. The sample analysed comprised multi-detector computed tomography cranial scans of 400 individuals equally distributed by sex. Following 3D volume rendering, 31 landmarks were acquired using OsiriX, from which a total of 18 linear inter-landmark measurements were calculated. Measurements were analysed using basic descriptive statistics and discriminant function analyses employing jackknife validations of classification results. All measurements (except frontal breadth and orbital height - Bonferroni corrected) are sexually dimorphic with sex differences explaining 3.5-48.9% of sample variance. Bizygomatic breadth and maximum length of the cranium and the cranial base contribute most significantly to sex discrimination; the maximum classification accuracy was 90%, with a -2.1% sex-bias. We conclude that the cranium is both highly dimorphic and a reliable bone for estimating sex in Western Australian individuals.

Concordance of traditional osteometric and volume-rendered MSCT interlandmark cranial measurements.

The statistical quantification of error and uncertainty is inherently intertwined with ascertaining the admissibility of forensic evidence in a court of law. In the forensic anthropological discipline, the robustness of any given standard should not only be evaluated according to its stated error but by the accuracy and precision of the raw data (measurements) from which they are derived. In the absence of Australian contemporary documented skeletal collections, medical scans (e.g. multislice computed tomography-MSCT) offer a source of contemporary population-specific data for the formulation of skeletal standards. As the acquisition of morphometric data from clinical MSCT scans is still relatively novel, the purpose of this study is to assess validity of the raw data that is being used to formulate Australian forensic standards. Six human crania were subjected to clinical MSCT at a slice thickness of 0.9 mm. Each cranium and its corresponding volume-rendered three-dimensional MSCT image were measured multiple times. Whether differences between MSCT and dry bone interlandmark measurements are negligible is statistically quantified; intra- and inter-observer measurement error is also assessed. We found that traditional bone measurements are more precise than their MSCT counterparts, although overall differences between the two data acquisition methods are negligible compared to sample variance. Cranial variation accounted on average for more than 20× the variance explained by MSCT vs. bone measurements. Similarly, although differences between operators were sometimes significant compared to intra-operator variance, they were negligible when compared to sample variance, which was on average 12× larger than that due to inter-operator differences.

The application of traditional and geometric morphometric analyses for forensic quantification of sexual dimorphism: preliminary investigations in a Western Australian population.

A current limitation of forensic practice in Western Australia is a lack of contemporary population-specific standards for biological profiling; this directly relates to the unavailability of documented human skeletal collections. With rapidly advancing technology, however, it is now possible to acquire accurate skeletal measurements from 3D scans contained in medical databases. The purpose of the present study, therefore, is to explore the accuracy of using cranial form to predict sex in adult Australians. Both traditional and geometric morphometric methods are applied to data derived from 3D landmarks acquired in CT-reconstructed crania. The sample comprises multi-detector computed tomography scans of 200 adult individuals; following 3D volume rendering, 46 anatomical landmarks are acquired using OsiriX (version 3.9). Centroid size and shape (first 20 PCs of the Procrustes coordinates) and the inter-landmark (ILD) distances between all possible pairs of landmarks are then calculated. Sex classification effectiveness of the 3D multivariate descriptors of size and shape and selected ILD measurements are assessed and compared; robustness of findings is explored using resampling statistics. Cranial shape and size and the ILD measurements are sexually dimorphic and explain 3.2 to 54.3 % of sample variance; sex classification accuracy is 83.5-88.0 %. Sex estimation using 3D shape appears to have some advantages compared to approaches using size measurements. We have, however, identified a simple and biologically meaningful single non-traditional linear measurement (glabella-zygion) that classifies Western Australian individuals according to sex with a high degree of expected accuracy (87.5-88 %).