Boxplot showing the distribution of the angle between the dorsal margin of the rostrum and the maxillary tooth
row 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 a subadult skull of Edmontosaurus annectens (CMN 8509). Grey horizontal lines delimit character states.