Boxplot showing the distribution of the ratio between the height and length of the skull 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 skull of
Corythosaurus intermedius (CMN 8704). Grey horizontal lines delimit character states.