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

Ontogenetic shape variation in the cranium of Rungwecebus kipunji


Department of Anatomy, Chicago College of Osteopathic Medicine, Midwestern University

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The cranial morphology of the endemic Tanzanian primate Rungwecebus kipunji is known only from juvenile specimens. Morphometric analyses of the first voucher specimen, an M1-stage male (FMNH-187122), identified similarities with Lophocebus aterrimus but supported the kipunji’s generic status. The second voucher specimen, an M2-stage male (SHCP-2458), has undergone qualitative and phylogenetic analyses but has not been included in multivariate, morphometric studies. In this study, 3D geometric morphometrics was used to compare the cranial morphologies of FMNH-187122 and SHCP-2458. To facilitate comparisons, developmental simulation was used to estimate the M1-stage morphology of SHCP-2458, M2-stage morphology of FMNH-187122, and adult morphologies of both specimens. Objectives were to evaluate the affinities of SHCP-2458, characterize kipunji cranial development, and explore the impact of ontogenetic variation on estimates of adult morphology. Coordinate data were collected on 109 juvenile and adult-male crania representing five African papionin genera. The male developmental trajectory for each species was approximated by regression of Procrustes-aligned coordinates on dental stage. Juvenile and adult landmark configurations were simulated by application of developmental vectors to the juveniles’ landmark coordinates. Affinities of actual and simulated kipunji crania were assessed using Procrustes distances and PCA. Next to FMNH-18722, SHCP-2458 is most similar to M2-stage Lophocebus aterrimus. Shape differences between FMNH-18722 and SHCP-2458—concentrated in the face and neurocranium—are greater than between M1- and M2-stage Lophocebus but similar in magnitude to Papio. Vectors of L. aterrimus and Papio provide the most accurate estimates of actual juvenile morphology. Affinities of simulated juveniles and adults will be discussed.

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