Interspecific comparison of ontegenetic change in temporal bone pneumatization (918.22)

Abstract

Comparative studies of temporal bone pneumatization in adult chimpanzees and modern humans have shown that human temporal bones have reduced pneumatization compared to chimpanzee temporal bones, following the general trend towards reduction in pneumatization over the course of hominid evolution. Although the adult pattern of pneumatization in chimpanzees is well studied, extensive quantitative comparisons of the ontogenetic change in pneumatization of the temporal bone in chimpanzees and modern humans have not been completed. The purpose of this study is to compare patterns of ontogenetic change in temporal bone pneumatization in humans and chimpanzees.High resolution computed tomography scans were acquired from cross‐sectional ontogenetic series of human (n=29) and chimpanzee (n =30) temporal bones. The sample included individuals ranging in age from neonate to adult for both species. Surface areas and volumes of the temporal bone air cell tracts were calculated using Amira for both species.Results indicate that, from an early age, chimpanzees show larger surface areas and volumes of the temporal bone air cell tracts compared to modern humans. Although there are some differences in timing of pneumatization in the two species, these differences in size may result from the progression of the air cells from both the mastoid and squamous antrums in chimpanzees. This study highlights the early establishment of adult size differences in pneumatization.