In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms. The phenotype is Large fontanelles (Human Phenotype Ontology id HP_0000239). Also known as: Enlarged fontanelles, Large fontanel, Large fontanelle, Large fontanels, Persistent wide fontanel, Wide fontanelles.