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This study employs geometric morphometric methods to investigate the morphology and shape change of the frontal bone for Pan troglodytes and Pan paniscus. Unlike previous work on the topic, this research analyzed morphology and ontogenetic shape change in a single bone of the cranium, namely the frontal bone. Frontal bone shape was compared between juvenile Pan troglodytes and Pan paniscus and the ontogeny of the bone was assessed in Pan paniscus infants and juveniles. Analyses were performed on frontal bone morphology with and without the browridge in order to assess the morphology of the frontal apart from influences affecting the browridge. Results of ANCOVA with principal component shape variables indicate that the frontal bone shape differs between species (P=.000) and between infant and juvenile Pan paniscus for log centroid size (P=.109), but this shape change occurs largely in the browridge. Results for the frontal without the browridge do not significantly differ in shape between species for PC1 (P=.205) and PC3 (P=.113) and between Pan paniscus life stages for PC3 (P=.103). These results have implications for current and future work as they contribute to a growing body of knowledge aimed at understanding the complexities of cranial growth.
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