1Àrea de Paleoprimatologia i Paleontologia humana, Institut Català de Paleontologia Miquel Crusafont (ICP), 2Àrea de Paleontologia Virtual, Institut Català de Paleontologia Miquel Crusafont (ICP), 3Department of Vertebrate Paleontology, American Museum of Natural History and NYCEP, 4Àrea de Paleoprimatologia i Paleontologia humana, ICREA at Institut Català de Paleontologia Miquel Crusafont and Unitat d'Antropologia Biològica
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The cortical thickness of the femoral neck has been traditionally related to positional behaviors, since bone tissues are sensitive to mechanical stresses. Previous works have been mostly focused on distinguishing bipeds from other locomotor groups among primates. However, several authors have proposed that differences among other types of locomotion could be also tested. Here we analyze the correlation between the superior and inferior cortex of the femoral neck amongst extant primates (including prosimians, monkeys, apes and humans) in relation to locomotion. The Late Miocene (MN 10) hominoid Hispanopithecus laietanus from Can Llobateres (NE Spain) is also included in order to make locomotor inferences for this taxon. The right femur of this species was scanned using computed tomography and the cortical thickness of the femoral neck was quantified taking lineal measurements of the superior and inferior cortices. Morphometric comparisons reveal that suspensory apes display a more homogeneous distribution of cortical bone than other primates (bipeds, quadrupeds and vertical-clingers-and-leapers), which show a superior cortex thinner than the inferior one. Hispanopithecus laeitanus presents a 1:1 proportion of its cortical thickness, i.e., the thickness of the cortex is virtually the same both superiorly and inferiorly, as in extant apes. Hence, in agreement with previous finds, the locomotor repertoire of Hispanopithecus is inferred to have included a significant suspensory component.
We thank J.C. Ohman and C.O. Lovejoy for allowing us to use their data. This work has been supported by the Spanish Ministerio de Ciencia e Innovación (CGL2008-00325/BTE, and RYC-2009-04533 to D.M.A.) and the Generalitat de Catalunya (2009 SGR 754 GRC, and BP-A 00226to S.A).