14 - Ontogenetic patterning and phylogenetic significance of mental foramen number and position in the evolution of Upper Pleistocene Homo sapiens

Summary

Introduction

In the last decade, a number of new Pleistocene subadults have been discovered in Europe, Asia and the Levant, from sites including Moula-Guercy, France (Defleur et al., 1999), Sima de los Huesos, Spain (Arsuaga et al., 1997), Lagar Velho, Portugal (Duarte et al., 1999), Mezmaiskaya in the northern Caucasus (Golovanova et al., 1999), and Dederiyeh in Syria (Akazawa et al., 1995, 1999). As the available sample of immature remains dating to the later phases of hominid evolution continues to grow, our opportunities to better understand the developmental patterning underlying the range of morphological variability demonstrated by adults of Upper Pleistocene populations improve.

Neandertal mandibles differ from those of modern humans in a number of features including the usual lack of a mental eminence (Le Gros Clark, 1964), possession of a large retromolar space (de Lumley, 1973), a hook-shaped coronoid process with a vertical height often exceeding that of the condylar process (Minugh-Purvis & Lewandowski, 1992), and unique configuration of the superior ramus (Rak et al., 2002). The anterior mandibular region of Homo is particularly enigmatic in that late in hominid evolution its profile changes dramatically with the appearance of the chin, a phenomenon which has long been of interest to paleoanthropologists (Schwartz & Tattersall, 2000). Although some Neandertals possess a fairly vertical labial aspect of the mandibular symphysis or even a rudimentary mental eminence, close scrutiny of this region reveals several differences in the morphological details contributing to the formation of a modern human, as opposed to a Neandertal, chin (Arensburg et al., 1989; Coqueugniot, 1999; Mallegni & Trinkaus, 1997; Minugh-Purvis, 2000; Tillier, 1981; and others).