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.

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.

Abstract:The reconciliation of skeletal and chronological age is of paramount concern in the context of criminal proceedings involving living individuals, who frequently lack any associated identification documentation, and are referred to the criminal justice system. It is important to appreciate that skeletal and chronological ages are not the same measurement of time-since-birth, and depending on the analytical approaches applied, there will be an inherent source of variation between estimated (biological: skeletal, physical, and psychological) and actual (legal) age. Given the evidentiary value attached to the estimation of age based on the subjective assessment of biological and psychological developmental attributes, it is timely to consider current approaches toward achieving the latter. The aim of this review is to first explore a selection of circumstances that result in requests for forensic age assessment in living individuals. Issues pertaining to competency to perform an assessment, sources of error that may be introduced, and how to accordingly quantify the level of uncertainty in the final estimation are then considered. This logically leads into discussions of the necessity for population-specific statistical biological data. Current methods based on psychological development, dental status, and skeletal maturation are then reviewed. The review concludes by exploring future research and practical directions in the context of medico-legal practice and social consequences.

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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.