intramembranous bone

Intramembranous bone formation is the simpler process, and it's responsible for forming a person's skull and lower jawbone.

Reptiles and most non-mammalian therapsids have a large, paired, intramembranous bone behind the premaxilla called the septomaxilla.

It appears likely that the primary defect in Aarskog-Scott syndrome is an abnormality of FGD1/Cdc42 signaling resulting in anomalous embryonic development and abnormal endochondral and intramembranous bone formation.