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

A morphometric analysis of cranial ontogeny in the Hominoidea: implications for the growth and development of fossil primates


1Anthropology, University of Toronto, 2Human Evolution, Max Planck Institute for Evolutionary Anthropology Leipzig, 3Anthropology, University of Toronto

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Many studies have applied information on African ape and human ontogeny to interpret the biology of fossil hominins. However, in the analysis of stem hominoids and hominids, data from all extant non-human apes are needed to model ontogeny. To this end, we use geometric morphometrics to investigate patterns of cranial growth in extant hominoids, including hylobatids, for which very little data are currently known.

In order to examine growth allometry in hominoids, three-dimensional coordinates of 145 landmarks and 313 semilandmarks were measured on CT and surface scans from an ontogenetic sample of hominoid crania, comprising Pan, Gorilla,Pongo, Hylobates, and Symphalangus. After Procrustes superimposition, principal component analyses were computed in shape and form space. We used regressions of shape coordinates on centroid size to assess within-group static and ontogenetic allometric trajectories.

We find that genus level differences are present in early life, and that the subsequent ontogenetic trajectories are almost parallel. This corroborates previous studies suggesting that many aspects of cranial development are shared among hominoids. In the first three principal components of shape space, Pongo specimens plot closely to the ontogenetic trajectories of the African great apes. Hylobatidae are distinctly different from all the great apes. However, as expected, Hylobates and Symphalangus plot close to each other in shape space.

We visualize and discuss aspects of cranial development that are shared among all hominoids as they are potentially informative about the development pattern of the last common ancestor of great apes and hylobatids.

This study is funded by the University of Toronto, the Max Planck Institute for Evolutionary Anthropology, and NSERC.

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