Monarch Disease Ontology identifier MONDO_0007971 (delayed membranous cranial ossification) is a rare, genetic primary bone dysplasia characterized by absent ossification of calvarial bones at birth and characteristic facial dysmorphisms (frontal bossing, hypertelorism, downward-slanting palpebral fissures, proptosis, flat nasal bridge, low-set ears, midface retrusion). Patients present a soft skull at birth which, over time, progressively ossifies and in adulthood typically results in a deformed skull (with brachycephaly and prominent occiput). No other skeletal abnormalities are associated and patients have normal cognitive and motor development. Also known as: Gonzales-del Angel syndrome.