Abstract:
Phylogenetic relationships among extinct hominoids (apes and humans) are
controversial due to pervasive homoplasy and the incompleteness of the fossil record. The bony
labyrinth might contribute to this debate, as it displays strong phylogenetic signal among other
mammals. However, the potential of the vestibular apparatus for phylogenetic reconstruction
among fossil apes remains understudied. Here we test and quantify the phylogenetic signal
embedded in the vestibular morphology of extant anthropoids (monkeys, apes and humans) and
two extinct apes (Oreopithecus and Australopithecus) as captured by a deformation-based 3D
geometric morphometric analysis. We also reconstruct the ancestral morphology of various
hominoid clades based on phylogenetically-informed maximum likelihood methods. Besides
revealing strong phylogenetic signal in the vestibule and enabling the proposal of potential
synapomorphies for various hominoid clades, our results confirm the relevance of vestibular
morphology for addressing the controversial phylogenetic relationships of fossil apes.
