Three-dimensional analysis of mandibular dental root morphology in hominoids.

Although often preserved in the fossil record, mandibular dental roots are rarely used for evolutionary studies. This study qualitatively and quantitatively characterizes the three-dimensional morphology of hominoid dental roots. The sample comprises extant apes as well as two fossil species, Khoratpithecus piriyai and Ouranopithecus macedoniensis. The morphological differences between extant genera are observed, quantified and tested for their potential in systematics. Dental roots are imaged using X-ray computerized tomography, conventional microtomography and synchrotron microtomography. Resulting data attest to the high association between taxonomy and tooth root morphology, both qualitatively and quantitatively. A cladistic analysis based on the dental root characters resulted in a tree topology congruent with the consensus phylogeny of hominoids, suggesting that tooth roots might provide useful information in reconstructing hominoid phylogeny. Finally, the evolution of the dental root morphology in apes is discussed.