has part has part has_part characteristic of part of has modifier abnormal neurocranium morphology abnormal occipital bone morphology The basioccipital, exoccipital and supraoccipital bones are distinct bones in prenatal, neonatal and some early juvenile stages in most mammals. In adult organisms, these structures are fused to form the unified adult occipital bone. This term refers to the adult mammalian structure. MPheno.ontology MP:0005269 any structural anomaly of the bone at the lower, posterior part of the skull occipital bone dysplasia morphology abnormal occipital bone