Boxplot showing the distribution of the angle of ventral deflection of the preacetabular process of the ilium 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 this angle was measured, exemplified in the ilium of Barsboldia
sicinskii (ZPAL MgD-I 110). Grey horizontal lines delimit character states.