Evolutionary Trends in the Temporal Bone in the Neandertal Lineage: A Comparative Study Between the Sima de los Huesos (Sierra de Atapuerca) and Krapina Samples

A comparative study of the temporal bone in the fossil human collections from the Middle and Upper Pleistocene sites of the Sima de los Huesos (Spain) and Krapina (Croatia), respectively, has revealed a pattern to the emergence of several Neandertal features in the glenoid fossa and mastoid process. The results demonstrate that a flattened articular eminence characterizes the Neandertal evolutionary lineage, and this apparently derived feature is present at least since the time of the Atapuerca (SH) hominids. In contrast, both the size of the postglenoid process and the projection of the mastoid process have clearly undergone a reduction in the Neandertals, including the Krapina sample, from their Middle Pleistocene precursors. The anterior mastoid tubercle is absent in both the Atapuerca (SH) sample and the Krapina hominids, but is ubiquitous in Upper Pleistocene Western European Neandertals, suggesting a later appearance of this feature. Finally, the narrow width of the mastoid process in the Krapina sample appears to be a feature which is particular to this sample.