Boxplot showing the distribution of the angle between the proximal medial margin of the surangular and
the proximal medial margin of the caudal process for a sample of iguanodontoidean taxa. 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 a dentary of Lambeosaurus lambei (CMN 2869). Grey horizontal lines delimit character states.