The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

How to distinguish and analyse locomotor groups in the Hominoidea: analysis of supraspinous and infraspinous fossae with geometric morphometrics, 3D laser scanning and new methodologies to measure muscle mass


1Anthropology Unit, Animal Biology Department, University of Barcelona, 2Unit of Human Anatomy and Embryology, University of Barcelona

Friday 11:15-11:30, Galleria North Add to calendar

Extant hominoids share an orthograde corporal pattern, which allows the free movement of the glenohumeral joint, permitting the appearance of new forms of locomotion.

This study provides a quantitative analysis of the posterior side of the hominoid scapula, including modern humans. Our objective is to find patterns of variation in scapular shape through a multivariate analysis of morphological features in order to distinguish different types of locomotion observed in hominoids and thus to be able to better understand the locomotor patterns of fossil taxa. We apply 2D geometric morphometrics, 2D areas, 3D real areas, the classical spinal fossae index, and compare the results with muscular weights obtained from dissections of primate cadavers.

Our results suggest that knuckle-walking was independently acquired in Pan and Gorilla, and that the last common ancestor of humans and chimpanzees was mainly arboreal, with a shoulder morphology similar to that of orangutans. We conclude that the new methodologies applied are useful tools to study the morphology of the scapula and its muscles. The detailed analysis of the morphology of the posterior side of the scapula is particularly suitable to differentiate the types of locomotion observed in hominoids. Moreover, even if one should be careful about inferring conclusions based exclusively on the study of bones because a substantial part of the data about soft tissues is lost, by using our methodologies it is possible to estimate quite accurately whether a scapula (based only on the morphology of this bone) belongs or not to a particular locomotor group.

This research was supported by the Spanish Ministry of Education and Science (MEC) Funding for Research Projects (MEC CGL2010-15340), the Generalitat de Catalunya Funding for Consolidate Research Groups (DURSI 2009SGR-00884), and the Predoctoral Fellowship Grant Program of the Ministry of Education and Science (MEC) FPU (AP2008-00877).

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