has part has part has_part characteristic of part of has modifier abnormal exoccipital bone morphology any structural anomaly of the bone or region on the lateral sides of the great foremen of the skull, which often forms a part of the occipital in the adult, but is usually distinct in the young MPheno.ontology exoccipital bone dysplasia 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. MP:0000080 abnormal occipital bone morphology morphology abnormal exoccipital bone