A novel landmark-based morphometric approach for sequencing typical thoracic vertebrae

The methods for reassociating and sequencing the thoracic vertebrae are based mainly on the morphological characteristics of the bones and the expertise of the forensic anthropologist. However, the thoracic vertebrae T2-T9 show no morphological differences, and therefore, it is challenging to reassociate and sequence them, especially in cases of commingling or extensive trauma. The aim of this study was to develop a new method based on the integration of 3D geometric morphometric analysis from 3D models to provide accurate results regarding the sequencing of the thoracic vertebrae. The sample consisted of 98 individuals from three different skeletal assemblages from various contexts of Greece and was scanned with a handheld 3D scanner. A total of 28 landmarks were placed on the 3D models of the vertebrae. The shape of each vertebra was compared to a reference sample. The identification rates showed that T2 had the highest identification rates and T6 the lowest. Each vertebra was matched to its anatomical counterpart within the first three possible selections of the reference skeleton, in a percentage greater than 67% and in most cases, more than 81%. On the contrary, T6 had a rate lower than 50%. It is proposed that the presented method be examined in other samples to see its application as a tool for sequencing the typical thoracic vertebrae.