The nasal region of the ~417 ka Sima de los Huesos (Sierra de Atapuerca, Spain) Hominin: New terminology and implications for later human evolution

Abstract

Circum-nasal and nasal cavity morphology add to the picture of the Sima de los Huesos specimens as, at one level, representing a distinct morph and, at another, displaying individual variation. They developed a robust, midline-grooved, three-dimensional spinal ridge lying anteriorly in the nasal cavity floor that was distended posteriorly over the nasal cavity floor, and, typically, an expansive, three-dimensional patch of rugose bone on the nasal cavity wall where a conchal crest would otherwise lie. They vary, for example, in degree of topographic relief of the nasal cavity wall, expression of the spinal ridge, and development of nasal crests and fossae. Lacking an anterior nasal spine, Sima specimens differ from extant and most fossil Homo sapiens, some specimens attributed to H. heidelbergensis, and the Gran Dolina partial face, whose anterior nasal spine is a superoanterior distention of the nasoalveolar clivus, and also from Neanderthals, whose anterior nasal spine projects anteriorly away from the nasoalveolar clivus. Comparison of Neanderthals, the Sima hominin, and specimens regarded as H. heidelbergensis calls for re-evaluating the integrity of “heidelbergensis” and rethinking the phylogenetic relationships of them all. To precisely describe the numerous features and combinations thereof of the nasal region in Sima specimens, and compare them with Neandertals and “H. heidelbergensis”, we developed terminology that is applicable not only to hominins, but to mammals in general.