Figure 2: Growth directions of the maxilla.
From: Ontogeny of the maxilla in Neanderthals and their ancestors
Schematic illustrates the principal growth direction of the maxilla in the Sima de los Huesos (SH) fossils, Neanderthals and modern humans. The growth remodelling identified in this study impacts growth direction in at least two ways. (i) The extensive bone deposits over the maxilla are consistent with a strong forward growth component in the fossils (purple horizontal arrows); whereas resorption over this region in the modern human face moderates forward displacement (blue horizontal arrow). (ii) Widespread deposition in the fossils combined with larger developing nasal cavities displaces prosthion downward and more anteriorly than in modern humans as indicated by the angles of the downward arrows. In humans, forward displacement is more limited with resorption compensating the anterior cortical remodelling drift of prosthion as indicated by a more downward pointing arrow. As a result of a more anterior location of prosthion in the fossil taxa, the tooth row en bloc drifts forward with respect to the maxillary tuberosity, thus generating the retromolar space characteristic of Neanderthals and also in some SH fossils.
