A morphological analysis of the modern human frontal bone from Hahnöfersand, Germany

Frontal bone morphology is considered informative concerning phylogenetic and taxonomic affinities in hominin fossils. However, evaluating individual frontal bone features, especially macroscopically and with qualitative data, can produce contradictory results. One example is the enigmatic frontal bone from Hahnöfersand, Germany, initially dated to ca. 36 ka. A previous description of this specimen found that it exhibits a mix of modern human- and Neanderthal-like features and interpreted it as a potential hybrid between Homo neanderthalensis and Homo sapiens. In this case study, we apply a nearly landmark-free technique (i.e., surface registration) to reassess Hahnöfersand’s supposed intermediate morphology in the context of a revised chronology of ca. 7.5 ka. A three-dimensional comparative analysis was conducted using a dataset of Neanderthals, Middle Pleistocene European hominins, and a diverse Homo sapiens sample. Principal components analysis, Mahalanobis distances, and pairwise Procrustes distances place Hahnöfersand within the variability of Holocene Homo sapiens, with no evidence of intermediate morphology. These findings support Hahnöfersand’s attribution to recent Homo sapiens and highlight the efficacy of the surface registration method for morphological assessments of taxonomy in isolated fragmentary remains, where interpretation is driven entirely by the preserved morphology and, if available, dating.