Final answer:
The age at which the coronal suture closes is not specified, but it commonly starts closing in adulthood, and the timing can be affected by various factors.
Step-by-step explanation:
The coronal suture is a joint that unites the frontal bone to the right and left parietal bones across the top of the skull. The age at which the coronal suture closes can vary, and while there is no precise age mentioned in the provided materials, the process typically begins in adulthood. The closing of cranial sutures occurs late in life and is different for each individual, with other factors such as genetics and health conditions like craniosynostosis potentially affecting the timing. Synostosis is the term used when the connective tissue ossifies and the bones fuse completely. For perspective, the anterior fontanel, which is among the last to close, typically ossifies between 9 to 18 months after birth, while the coronal suture takes much longer and is usually one of the last sutures to close.