Morphometric analysis of the petrous bone - A preliminary study of intra- and inter-observer variation of basic measurements.

Abstract

Studies of cremated skeletal remains show that the petrous part of the temporal bone often survives the burning process due to its dense and robust structure. Because of its frequent occurrence and well preservation in skeletal material from archaeological and forensic context, it has repeatedly been investigated for patterns of sexual dimorphism and potential to estimate sex from skeletal remains. Although being a relatively small skeletal element, the posterior part of the petrous bone has several anatomical features that serve as characteristic landmarks for the application of metric studies. Furthermore, sex-specific differences have also been recognised for the dimensions of the medial and lateral angle of the Internal acoustic canal (IAC). However, the accuracy of estimating an individual's sex based on measurements of the petrous bone has met with varying degrees of success. The purpose of this study was to see how well certain variables were identified and measured, but also to recognise the reproducibility of the results. In an initial approach five variables were selected and measured on ten petrous bones from an archaeological context. In addition, a total of forty casts were prepared in order to measure the angular dimensions. It was found that the basic measurements of all variables show high variations, but in only one variable, measurements were very inconsistent as evidenced by the large intra- and inter-observer errors. In terms of the angle dimension the results show that the range of variation was higher for the lateral angle and that the intra-observer error was found to be much lower for the medial angle than for the lateral one. The results show potential in the use of these methods in terms of repeatability, but also indicate that the metric assessment is prone to false application caused by the morphological variations of the individual landmarks.