Fig. 8
From: Developmental constraint through negative pleiotropy in the zygomatic arch
Potential developmental mechanisms underlying zygomatic arch variation. Schematic models of developmental mechanisms by which an a adult phenotype of relative skeletal contribution to the zygomatic arch might occur. Options include b external regulatory definition of a presumptive suture, c differences in initial mesenchymal condensation size, and d differences in relative growth or ossification rates between the two bone primordia