Research in hominoid cranial ontogeny has provided significant insight into the similarities and
differences between apes and humans. Additionally, questions about within-species variability,
allometry, and levels of sexual dimorphism in fossil hominoids are commonly addressed using
the extant great apes as a comparative framework. However, this model is incomplete without
the addition of the lesser apes, gibbons and siamangs. This analysis completes the hominoid
record of cranial ontogeny with the addition of the Hylobatidae, and provides a full description
of their cranial ontogeny and adult variation. 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, with a
cercopithecoid out-group, Colobus. After Procrustes superimposition, principal component
analyses were computed in shape space. Regressions of shape coordinates on centroid size were
used to assess within-group ontogenetic and static allometric trajectories. Results indicate that
the shape changes during ontogeny in gibbons are similar to the shape changes previously
reported for great apes. Genus-specific differences are already observable early in ontogeny, and
the subsequent ontogenetic trajectories are almost parallel. Sexual dimorphism for both shape
and size is found in Symphalangus adults, which was previously unobserved. Analysis of all taxa
in the sample shows nearly parallel ontogenetic trajectories within the Hominoidea, which is
consistent with previous studies. With the addition of hylobatids and Colobus, this analysis
demonstrates that cranial ontogeny is highly conserved in the Catarrhini. Given the existence of
this basic catarrhine growth trajectory, it should be possible in the future to predict fossil taxa
morphologies at any stage of growth.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/43626 |
| Date | 10 January 2014 |
| Creators | Kozakowski, Stephanie |
| Contributors | Begun, David |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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