Estudio y caracterización morfológica de los patrones de crestas del trigónido y talónido en el esmalte y en la dentina de los homininos del pleistoceno de la Sierra de Atapuerca (Burgos) mediante técnicas de microtomografía computarizadacomparativa con otros grupos humanos e inferencias evolutivas

Abstract

ABSTRACT Teeth are an important source of morphological traits with taxonomic and phylogenetic value. In addition, their high component of genetic expression makes them the "black box" of genetic code. Through this PhD dissertation we have characterized and compared the pattern of expression of talonid and trigonid crests at the enamel and dentine for most European Pleistocene hominins. In addition, to understand the polarity of these morphological features and to contextualize the evolution of European populations, we have also analyzed other specimens from Africa, Asia and the Middle East. Our total sample consists of 274 molars that have been analyzed by means of micro-computed tomography (micro CT). We present the intra- and inter-population variability in the expression of the trigonid and talonid crests in these groups and assess the correlation between the enamel and dentine surfaces. Our data ratify that the trigonid crests patterns are taxonomically and phylogenetically useful. Sima de los Huesos and H. neanderthalensis are phenetically closer in their high frequencies of continuous trigonid crests. This pattern contrasts with the lower frequencies of H. antecessor and H. sapiens. Our results reinforce the hypothesis that the Sima de los Huesos population belongs to the Neanderthal lineage and, in accordance with recent paleogenetic studies, pushes back the split of H. sapiens and H. neanderthalensis and compels to reassess the phylogenetic position of H. antecessor. Our study confirms that H. antecessor has a unique morphological mosaic of primitive and derived features regarding the Homo clade and would support its position close to the node of divergence of H. sapiens and H. neanderthalensis. Finally, our results point to a less linear settlement of Europe, where H. antecessor might represent one of the successive hominin waves into this continent, possibly from Western Eurasia. Subsequent dispersals at different times could explain the variability of the European Middle Pleistocene population. Keywords: Holocene; Pleistocene; Human Evolution; Europe; Sierra de Atapuerca; Sima de los Huesos; Homo antecessor; H. neanderthalensis; Homo sapiens; microCT; dental morphology; talonid crests; trigonid crests.