Does space in the jaw influence the timing of molar crown initiation?
Radiographic and histological studies of baboon (Papio hamadryas, P. anubis) and chimpanzee (Pan troglodytes) permanent tooth development have found that periods of molar crown mineralization overlap markedly in chimpanzees but are staggered in baboons. Here we test the hypothesis that these intertaxon differences in molar initiation are primarily due to the space available in the mandibles of each species for these teeth. This study includes radiographic, linear measurement, and three-dimensional (3D) coordinate landmark data taken from baboon (Papio anubis n=51) and great ape (Pan paniscus n=43, P. troglodytes n=60) mandibles and permanent molars across a broad developmental range for each taxon. Unexpectedly, 3D multivariate statistical shape analysis of the molar crypt, crown, and root data shows that all three species trajectories of molar row shape change are indistinguishable from each other. Qualitative analysis of these 3D data reveals subtle and inconclusive intergeneric diff
