Morphological comparison of the Pleistocene hominin lower molars from Atapuerca sites by means of microCT

Abstract

Since the Atapuerca fossils are the most representative remains to understand the evolution of the genus Homo in Europe during the Early and Middle Pleistocene, the study of their dentition is becoming increasingly important. Several discoveries (Bermúdez de Castro and Martinón-Torres, 2013; Martinón-Torres et al., 2007a; Meyer et al., 2014) propose that the human occupation of Europe during the Pleistocene depended upon the non-linear recruitment of populations from the central area of dispersals of Eurasia. Morphological comparisons between those populations will provide new and valuable information to investigate the evolutionary scenario of the first European settlement. The aim of this study is to explore the affinities between extant and extinct human population in Europe. For this purpose, and knowing that the expression of trigonid and talonid crest pattern seems to be of significant taxonomic and phylogenetic value (Bailey, 2002; Martínez de Pinillos et al., 2014; Martinón-Torres et al., 2014), we present a comparative study of these traits at the outer enamel surface (OES) and enamel dentine junction (EDJ) for H. antecessor, H. heidelbergensis (Sima de los Huesos samples), H. neanderthalensis and H. sapiens by means of microtomography (microCT). Our results reveals that despite of the wider variability of trigonid crests types at the EDJ compared to the OES, the correlation in the morphology of the inner and the outer surface of the lower molars is high. Furthermore and in accordance with previous works (e.g. Bermúdez de Castro et al., 2003; Martinón-Torres et al., 2013), we highligth a more primitive dental conformation in Gran Dolina TD6 hominins in comparison with more derive features in the European Middle Pleistocene hominins from Sima de los Huesos. To the light of our microCT study, we present some evolutionary interpretations of the relationship among the Early and Middle Pleistocene hominins of Europe, where the divergence of the features -primitive or derived is considered regarding to H. sapiens and H. neanderthalensis trigonid and talonid crest expression.