Bipartite parietal bone

This study reports the first case of the bipartite parietal bone in the Croatian modern and archaeological population. We have examined 458 skulls from Multi-Slice Computed Tomography (MSCT) images and found only one case of this trait (0.22%; 95%CI 0.01%-1.21%). The bone exhibiting an additional suture was the left parietal; the type of the trait was complete, horizontal, and asymmetrical. Some additional sutural bones were observed, including asterion and lambda ossicle and two lambdoid ossicles. Among the other epigenetic variants, parietal, zygofacial, oval, and mastoid foramina, frontal grooves, supratrochlear notch, and condylar canal were visible. The principal components analysis (PCA) of features extracted from the frontal, lateral, and posterior view of 110 female crania using a convolutional neural network (CNN) for image analysis demonstrated that the skull deviated from the average female skull in the population. The visual and metric examination of the skull showed ultrabrachycephaly, mild lateral deformational plagiocephaly, and depression on the posterior part of the skull. The rarity of this case in the Croatian population indicated that this variant could be interesting for both clinicians and forensic anthropologists, as it can be used as means of comparative identification. Further studies will show its importance in assessing population affinities and relations inside the graveyards.