by Jose Manuel de la Cuétara
De la Cuétara JM, Bastir M. 2009. Primate cranial base: analysis of mid and lateral elements in a cercopithecid sample using geometric morphometrics. Paleontologia i Evolució, memòria especial nº3, 47-48.
In the last century, the study of the cranial base has gained much importance for paleoanthropology due to its... more
In the last century, the study of the cranial base has gained much importance for paleoanthropology due to its structural and functional roles during development and evolution of the skull. Most studies have been centred on the analysis of basicranial morphology, mainly focused on the different factors that may influence cranial base flexion. Consequently diverse hypotheses have been proposed, being the neural ones the most important due to the close relationship between the brain and the basicranium and also because of the importance of encephalisation during primate and human evolution. Additionally, recent studies have shown how different parts of the cranial base are tightly related with the facial block, in the way that the anterior and middle cranial fossa (ACF and MCF) are integrated with the upper face and the midface respectively. In this context, the MCF gets special interest because of its interaction with the temporal and parietal lobes, parts of the brain which are thought to increase substantially during evolution. Several authors have suggested that evolutionary transformations of the MCF (mainly in the temporal region) may influence craniofacial morphology, affecting cranial base flexion and the facial block. Despite much research about basicranial flexion in the sagittal plane, its lateral variation is still quite unknown, being studied mostly in human-hominid samples. Here we analyse shape covariation between midline and lateral basicranial elements using geometric morphometrics in a relatively wide Cercopithecid sample (23 species, 126 individuals), combining lateral and axial X-rays images of each individual. Partial least squares and thin plate spline analysis suggest that cranial base morphology is related with variation in brain and face relative sizes. Preliminary results of ongoing research also suggest that increase in relative parietal and temporal lobes size (MCF) contributes substantially to brain size increase, so that larger MCF proportions appear to be related with flexed basicrania. These results may indicate possible structural and functional relationships that could explain the high degree of flexion observed in modern human. Future research analysing more taxa of the primate lineage, including modern humans and their ancestors, is expected to give more information about complex interactions between different craniofacial elements and its evolutionary relationships. Funding: CGL-2006-02131 (Ministerio de Ciencia e Inovacion)
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