Boxplot showing the distribution of the orientation of the basipterygoid process of the basisphenoid for a sample of iguanodontoidean ornithopods. The inserted smaller graph shows the Bayesian information criterion (BIC) for various numbers
of clusters in which the data can be classified. The photograph shows how the two variables of this raio were measured, exemplified in the parietal of Charonosaurus jiayinensis (CUST JV1251-57). Grey horizontal lines delimit character states.