Final answer:
The lambdoidal suture closure typically occurs during later adulthood, with significant individual variation in the exact timing. It is one of the cranial sutures, joining the occipital bone to the parietal bones and fuses much later compared to other sutures like the anterior fontanelle, which closes by 18 months after birth.
Step-by-step explanation:
The approximate age at which the lambdoidal suture begins to close is usually during later adulthood, although this can vary significantly among individuals. This suture is an inverted V-shaped joint that unites the occipital bone to the right and left parietal bones on the posterior part of the skull. Unlike some of the other sutures and fontanelles of the skull which close relatively early in life, such as the anterior fontanelle closure by 9 to 18 months after birth, sutures like the lambdoidal typically ossify and fuse much later. According to skeletal age-estimation procedures, including transition analysis, which examines cranial suture closure among other markers, closure of cranial sutures including the lambdoidal suture is observed late in life. The process of intramembranous ossification, which affects the development and closure of sutures, continues into adolescence, but the timeline for suture closure can extend well into adulthood, with considerable individual variation.