Spheno-occipital synchondrosis: Examining the degree of fusion in a South African Black skeletal sample

- Perfect repeatability and reproducibility of Shirley and Jantz (2011) staging method.
- Complete fusion of this synchondrosis was observed in all individuals older than 20.
- Fusion state of this synchondrosis can assist in age estimation of skeletons.

Estimating age-at-death is one of the many biological demographics that a forensic anthropologist needs to determine for a set of unknown skeletal remains. A useful skeletal developmental marker, which can aid in estimating age in sub-adult remains, is the state of fusion of the spheno-occipital synchondrosis. This study aimed to determine the repeatability of a three-stage scoring method and the age at which the spheno-occipital synchondrosis begins and completes fusion in a Black South African sample. A total of 147 male and female skeletal individuals aged between 12-30 years from the Raymond A. Dart Collection of Human Skeletons were included. The mean age-at-death noted for the commencement of fusion at the spheno-occipital synchondrosis was 16.2 (±2.9) years in females and 16.7 (±1.2) years in males, with females displaying signs of fusion taking place approximately three years before their male counterparts. Complete fusion of this skeletal developmental marker was observed in 100% of the sample over the age of 20 years, regardless of sex. A Kappa value of 1.0 was achieved when the repeatability and reproducibility of the three-stage scoring method was tested. Complete fusion of this synchondrosis occurred slightly later in this South African sample than that noted in previous literature. This finding may be attributed to the differences in health and socio-economic statuses between these different population groups, reiterating the need for population-specific data to be developed. The importance of noting the state of fusion of the spheno-occipital synchondrosis during the examination of relevant forensic cases may aid in the formation of a narrower age-at-death range for sub-adult and young adult skeletal remains.