Skull morphology and locomotor behavior: an adaptation to arboreal environment?
Résumé
The structural variations of the Cercopithecoidea and Hominoidea (Primates) skulls have been in
the center of numerous studies, notably on the areas linked to vision or diet. However, few
associations between their morphologies and lifestyle (arboreal and/or terrestrial) have been made.
Morphometric analyses realized in rodents (34 species, N=112) and some primates (8 species,
N=21) supported the presence of a locomotor signal in the skull, showed by a thinner and shorter
rostrum in arboreal rodents (Protoxerus stangeri, Ratufa affinis), also observed in the sampled
arboreal primates (Nycticebus bengalensis, Galago senegalensis) (Bento Da Costa et al.,
submitted). Thus, a similar signal could be present in Cercopithecoidea and Hominoidea at a larger
scale, yielding to this problematic: Could a shorter face be linked to an arboreal lifestyle? First
results based on landmark acquisition (3D specimens) show a discrimination between the
locomotor groups in function of the skull morphology, in particular in the elongation of the
rostrum, separating groups having different degrees of arboreality and terrestriality (55 species,
N=189). Indeed, the rostrum is shorter in most of the arboreal species, except for the Strepsirrhine
primates such as Varecia variegate (black-and-white ruffed lemur) and Otolemur crassicaudatus
(brown greater galago). This preliminary study needs to be pursued, considering the influence of
other parameters such as the phylogeny by the use of Phylogenetical Flexible Discriminant
Analysis, which will highlight the possibility of different evolutive scenarios between
Strepsirrhines and Catarhines Primates.