Bivariate fit of Age versus MaTHEP (Main DTG peak, °C) for several data available in our database, obtained from samples of amber of different ages, indicated as grey circles. A significant correlation coefficient (r = 0.5730, p < 0.0001) was obtained throughout the overall dataset. Black points along the regression line indicate the three samples of Thai amber. As the dependent variable, MaTHEP was considered in panel on the left (A), and Age in the panel on the right (B); respective equations obtained with standard least squares method are indicated above each graph. Complete list of data for regression is provided as supplementary information.