Age estimation in infant skeletal remains by measurements of the pars lateralis

The objectives of this work were to validate two published methods for subadult age estimation based on measurements of the pars lateralis, and to develop a new method based on a wider set of measurements using the Granada Osteological Collection. The pars lateralis of 127 individuals from 6 months prenatal to 4 years of age were measured, taking 6 measurements of the body, the anterior synchondrosis and the condyle. Length and width were used to validate the published methods. Regression functions using age as the independent variable were calculated using each of the six measurements taken, and functions for age estimation were obtained through classical calibration. Functions for calculation of the 95% confidence interval of the estimates were obtained through linear regression using the estimation errors. In the validation of the previous methods, one method showed a linear tendency of the differences, which can be attributed to a circularity in reasoning in the original work. In the other method, a tendency towards overestimation was found, which can be attributed to the limitations of the method itself. The new functions have a consistency rate of 92.2% to 97.1%; the functions derived from all measurements are useful from 6 months prenatal to 2 years of age. Moreover, the functions obtained are applicable to incomplete pars lateralis, allowing for age estimation in a wide set of contexts and providing straightforward age estimates with their respective margin of error.